RU188297U1 - BACTERICIDAL IRRADIATOR - Google Patents

Abstract

The claimed solution relates to sterilization and cleaning, and is of interest for disinfection and cleaning of air flows using bactericidal ultraviolet radiation, air purification in rooms and air conditioning systems. The technical result of the utility model is to reduce the cost of bactericidal irradiators and a significant increase in their effectiveness, that is, a decrease in their energy consumption. The technical result is achieved in that in a bactericidal irradiator comprising at least one low-pressure mercury lamp as a source of ultraviolet radiation of the bactericidal range for irradiating the sterilized air stream, an irradiator body with inlet and outlet sections for the sterilized air stream, covering the region irradiated by the ultraviolet radiation source air flow, the main part of the inner surface of which is made diffusely reflecting at least one in The fan for pumping the air flow through the irradiator, the irradiator housing is made of a substantially axisymmetric shape with a low-pressure mercury lamp located close to its axis and geometric parameters in accordance with the following conditions: s / (s + S) <0.1; d / D <0.2, where s is the internal surface area of the irradiator without a diffusely reflective coating, S is the internal surface area of the irradiator with a diffusely reflective coating, d is the diameter of the low-pressure mercury lamp, D is the characteristic internal transverse dimension (diameter) of the irradiator body . 8 s.p. crystals, 6 FIG.

Description

The claimed technical solution relates to sterilization and cleaning and is of interest for disinfection and cleaning of air flows using bactericidal ultraviolet radiation, air purification in rooms and air conditioning systems.

The bactericidal effect of ultraviolet radiation on biological objects (cells, bacteria, viruses, etc.) is well known. The bactericidal range primarily includes radiation of the wavelength range, approximately 200–300 nm, this radiation due to photochemical reactions in the cell leads to irreversible damage, including DNA and RNA (as well as proteins and other components of the cell). This determines the universal nature of the action of ultraviolet radiation on microorganisms, as a result of which they lose the ability to normal life and reproduction, that is, to death in the first or subsequent generation. However, it is important to note that the dose of ultraviolet radiation, which ensures the death of, for example, 99.9% of microorganisms, can vary widely depending on the spectrum of the radiation source and the specific type of microorganism, varying from ~ 0.4 kJ / m ³ for Staphylococcus aureus to ~ 25.7 kJ / m ³ for the tobacco mosaic virus when using radiation from a low-pressure mercury lamp with a wavelength of 253.7 nm ([1]: Guideline P 3.5.1904-04 “Using ultraviolet bactericidal radiation to disinfect indoor air”) .

The bactericidal effect of light allows the efficient use of ultraviolet emitters of the appropriate range for air sterilization. The most commonly used sources of such sources are low-pressure mercury lamps (RLND), both in the ozone-free version (the emitted wavelength of 253.7 nm, corresponding to the resonant transition of the mercury atom 6 ³ P ₁ -6 ¹ S ₀ ), and in the case of radiation on both the wavelengths of the main resonant transitions of the mercury atom, including the 6 ¹ P ₁ -6 ¹ S ₀ transition with a wavelength of 184.9 nm ([1], [2]: LIT website http://www.lit-uv. com / ru / company /). In some cases, it is preferable, primarily to suppress the repair capabilities of cells, to use broadband radiation sources, such as high-pressure mercury lamps ([1]), repetitively pulsed xenon lamps ([3]: site of NPP Melitta company http: / /www.melitta-uv.ru/technology/worky), as well as excimer (exciplex) lamps ([4]: patent RU 2440147, wavelengths and bandwidths of radiation of the main excimer molecules are presented, for example, in [5]: M. Lomaev I., Skakun BC, Sosnin E.A. et al. “Excilamps are effective sources of spontaneous UV and B UV radiation ”. UFN, 2003, v. 173, No. 2, pp. 201-217). Excimer lamps based on XeBr * molecules (emission band about 282 nm), XeI * (253 nm), KrCl * (222 nm), as well as emission bands of homonuclear molecules Cl2 * (259 nm) and Br2 can be used as a light source of the bactericidal range * (289 nm); Under certain conditions, simultaneous radiation in several bands of the bactericidal range, for example KrCl * and Cl2 *, can be realized in an excimer lamp.

When disinfecting air, bactericidal light sources can be used in open form, in this case, processing is carried out in the absence of people. However, more often bactericidal lamps (bactericidal light sources) are installed in the so-called closed bactericidal irradiator, which includes, in addition to the lamp (s) itself, a housing, most of whose inner surface is reflective, and the bactericidal radiation exit from the irradiator is blocked in one way or another. Typically, such an irradiator includes a lamp (s) power source and at least one fan for pumping the sterilized air stream. In addition, a closed bactericidal irradiator in many cases includes additional (primarily dust) filters and auxiliary elements for attaching the irradiator to the ceiling or wall of the room.

The inventive bactericidal irradiator belongs to the group of closed irradiators (recirculators) when the bactericidal luminous flux from the lamp (s) located in the enclosed space of the irradiator body does not have a direct exit to the outside ([1]). Air disinfection in such sterilization units is carried out by irradiating it in the process of pumping air flow from the inlet of the housing to its outlet, and the corresponding air flow is created using a fan (fans). A low-pressure mercury lamp is used as a source of bactericidal radiation, having a high efficiency (up to 40%) and a radiation wavelength of 253.7 nm, which is flare to the maximum bactericidal light efficiency (265 nm).

Closed bactericidal irradiators of this type are widely used for air disinfection in the presence of people. In the case of using ozone-generating mercury lamps emitting wavelengths of 254 and 185 nm (this is an additional channel for disinfecting the air flow), ozone-absorbing filters are installed at the output of the irradiator.

A large number of closed bactericidal irradiators for disinfecting air from different manufacturers is known, differing in various design details and a control system, including, for example, analyzers of the operating life, temperature and / or humidity of the environment, and / or voltage of the network, and / or operating time used in lamp irradiator and even microorganism sensors, the use of various filters at the inlet, most often dust, and at the outlet of the irradiator body to remove, for example, ozone ([6]: patent RU 2542508, [7]: patent RU 2340360, [8]: patent RU 2521321, [9]: patent RU 2270696), etc.

The specifics of using bactericidal radiation for air disinfection in closed irradiators is that only a negligible fraction of the radiated power is actually used to suppress the vital activity of microorganisms, and the bulk of the radiation is absorbed by the surface of the irradiator body. This is due to the fact that the absorption length of bactericidal radiation in the air even with a significant number of microorganisms (and dust) is tens or even hundreds of meters, which is many times greater than the dimensions of the irradiator body.

Thus, to increase the efficiency of the bactericidal irradiator, it is advisable to maximize the utilization rate of the bactericidal lamp flux K _f ([1]). This result is achieved by performing at least part of the surface of the inner surface of the irradiator body with reflective, most often used mirror-reflecting stainless steel or aluminum. The effective dose growth according to the company HOWATHERM Klimatechnik GmbH ([10]: http://www.howatherm.de/web/EN/) is about 1.3 for the reflective surface of the irradiator housing made of stainless steel and up to two times for the reflective surface of the housing polished aluminum irradiator.

For example, a polished stainless steel case is used in an aerolit-400 bactericidal irradiator (recirculator) manufactured by LIT ([2]) based on amalgam low-pressure mercury lamps. The known technical solution allows to increase K _f from the standard value for closed recirculators of 0.3 ÷ 0.4 ([1]) to ≈ (385 * 400) / (3600 * 80) = 0.53, here E = 385 J / m ³ - 99.9% volumetric dose of mercury lamp radiation required for the degree of sterilization of Staphylococcus aureus, 400 m ³ / h - recirculator capacity, 80 W × 3600 s - bactericidal radiation energy emitted per hour at the end of lamp life.

An even greater value of K _f can be obtained due to a separate aluminum reflector, as in the closed Goodman® UVX series irradiators ([11]: http://goodmanrussia.ru/index.php/produkciya/sterilizator-vozduha/2-sterilizator) or, which is preferable due to the deposition of an aluminum layer, for example, by vacuum deposition, on the inner surface of the irradiator body made of one-piece cast from high-impact chemically resistant plastic, as in the DEZAR-4 irradiator ([12]: http://www.panfundus.ru/dezinfekcia/ baktericid / dezar-4.html). In the latter case, based on the presented technical characteristics, it was possible to realize K _f about 0.6. A similar aluminum reflector is also used by Sanuvox Technologies Inc. ([13]: https: // www. Sanuvox.com/en/index. Php).

However, the values of K _f obtained in known bactericidal irradiators with mirror-reflecting bactericidal radiation on the surface of the casing are far from potential. In particular, the effective value of K _f decreases in known irradiators with specular reflection of radiation due to a significant difference in radiation doses near the light source and near the irradiator body. Given the fact that with a decrease in the dose of bactericidal radiation by only 2 ÷ 2.5 times, the share of surviving microorganisms increases many times - for example, 50 times for Staphylococcus aureus with a dose reduction from 385 J / m ³ to 167 J / m ³ , we can conclude that it is the minimum dose of bactericidal radiation in the volume of the sterilizer body that must correspond to the required degree of sterilization. Accordingly, the average dose of radiation in terms of volume and, as a consequence, the total power of bactericidal radiation and the power consumed by the irradiator increase with an inhomogeneous distribution of radiation over the volume of the sterilizer.

For modern closed bactericidal irradiators (recirculators), a sufficiently large capacity (from ~ 200 m ³ / h), the UV radiation power required for a degree of sterilization of 99.9% for Staphylococcus aureus is ~ 0.25 W / m ³ , which, taking into account the efficiency of amalgam mercury lamps η _L ~ 33% corresponds to a power consumption of ~ 0.75 W / m ³ . In addition, part of the recirculator’s power supply is spent on pumping the air flow, and the power usually required for pumping is relatively small and amounts to no more than 7–10% of the power of the light source in the absence of additional dust filters and up to 15% when using such filters. As a result, the power consumption consumed by known recirculators is usually 0.8 ÷ 1 W per cubic meter of air pumped per hour, that is, a recirculator with a capacity of 3000 m ³ / hour to ensure a 99.9% purification rate of Staphylococcus aureus consumes 2.5 ÷ 3 kW of electric power, of which 85 ÷ 90% goes to the generation of bactericidal radiation.

Thus, to increase the energy efficiency of bactericidal irradiators, it is necessary, first of all, to increase the efficiency of using bactericidal radiation. This is especially important if it is necessary to sterilize air containing microorganisms that are more resistant to UV radiation, for example, rotaviruses with a dose of 1400 J / m ³ necessary for the degree of sterilization to be sterilized ([1]), etc. - in this case, the power consumed by the irradiator increases by a factor of several (~ 4 times for rotaviruses).

A sharp increase in the efficiency of using bactericidal radiation can be realized with a diffusely reflecting inner surface of the irradiator body. Such a technical solution is described in application US 2012/0315184 A1 with a priority of 05/04/2012 ([14]) and is taken as a prototype. According to the indicated technical solution, the inner surface of the irradiator body is made of diffusely reflecting material with an effective reflection coefficient of at least 95%, which allows a multiple increase in the radiation intensity inside the volume of the recirculator, including in comparison with recirculators with an internal surface of mirror-reflecting materials (stainless steel , aluminum), as well as to provide a higher (compared to specular reflection) radiation uniformity in the volume of the irradiator (recirculator). As a material with a diffuse reflection coefficient of bactericidal radiation> 95%, the prototype indicates the expanded fluoroplastic (e-PTFE) manufactured by WL Gore and Associates (USA), that is, fluoroplastic-4 (teflon) with numerous evenly distributed evenly distributed in it air pores, usually occupying ~ 60 ÷ 70% of the volume. Light scattering at numerous fluoroplastic-air boundaries at an appropriate material thickness provides an effective diffuse reflection coefficient from it> 95%, it is crucial here that pure fluoroplast-4 (Teflon) practically does not absorb UV radiation of the bactericidal range.

(≥70%). На длине волны излучения РЛНД коэффициент преломления тефлона менее 1,4 и, таким образом, при нормальном падении коэффициент зеркального отражения <3%.Hereinafter, by the present invention, by a diffusely scattering surface we mean a substantially diffusely reflecting surface — one for which the diffuse component of the scattered (reflected) light substantially exceeds the mirror component, for example, such a surface for which the proportion of the diffuse component in the reflected light exceeds

(≥70%). At the RLND emission wavelength, the refractive index of Teflon is less than 1.4 and, thus, with a normal incidence, the specular reflection coefficient <3%.

It is also important here to indicate that reflection becomes essentially diffuse even if the surface is rough with sufficiently small-scale irregularities, in particular, reflection from the rough surface of aluminum is essentially diffuse. However, in this case, the effective coefficient of diffuse reflection from the rough surface of aluminum is not greater than the coefficient of reflection from the smooth mirror surface of aluminum and, accordingly, the use of a frosted (rough) aluminum surface of the illuminator body does not provide a significant advantage in the effectiveness of the bactericidal irradiator.

If a light source (sources) of power Q is located in a cavity of a diffusely scattering material with a high reflection coefficient R, then in the absence of absorption in the cavity material, the intensity I _{P of} the radiation incident on the surface of the cavity is determined from the energy conservation law:

here S is the total area of the inner surface of the cavity with a diffusely reflecting coating, α is the fraction of the area of the inner surface of the cavity that absorbs radiation or through which radiation leaves the cavity (the proportion of so-called geometric losses). The above formula is correct when α << 1 and due to the diffuse nature of the reflection, the radiation in the cavity is “well mixed”. From here

that is, the intensity of radiation incident on the surface of such a cavity increases by N = 1 / [1-R (1-α)] times compared to I _P = (Q / S) for a cavity in which the inner surface absorbs radiation. For example, for α = 0.02 and R = 0.99, the increase in the intensity of the radiation incident on the walls of the cavity is N = 33.6, for α = 0.04 and R = 0.98 we get N = 16.9. From the above examples and formula (2) it follows that for a significant amplification of radiation, even at R → 1, a small value of α is necessary (for α = 0.1, even at R = 0.995, the value is N≈9.5).

In the prototype example, the irradiator body has the shape of a rectangular parallelepiped with a length of 183 cm (72``) and a cross section S = 61 × 122 cm (24 '' × 48 '') through which air is pumped with a nominal flow rate ΔV ≈ 1.65 m ³ / s or almost 6000 m ³ / h (3500 cubic feet per minute), the air flow rate in the irradiation zone is ν = Q / S ≈ 2.2 m / s. A rectangular cross-section of the air flow is also used in the Aerolit-400 and DEZAR-4 closed bactericidal recirculators (irradiators) described above.

Near four vertices of a rectangular cross-section of the irradiator are four mercury low-pressure lamps (Fig. 7A, 7B of the prototype [14]), which provide the necessary bactericidal flow. To reduce the inevitable geometric radiation losses at the inlet and outlet of the recirculator, diaphragms are installed from the same diffusely scattering material with a set of relatively small holes for air passage made in them (Fig. 7B). The power consumed by the irradiator was 3.2 kW, respectively, the specific power consumption was about 0.5 W for each cubic meter of air pumped per hour.

It should be noted the significant power consumption for pumping air: the pressure drop ΔР in the prototype was 200 Pa, which with a typical efficiency of frequently used axial fans η _В ~ 30% corresponds to the power consumption pump system W _PR = ΔV * ΔР / η _В ~ 1 kW. The pressure drop in the prototype is many times (~ 66 times, 33 times at the inlet and outlet of the irradiator) exceeds the dynamic pressure of the air flow in the irradiation zone ρν ² / 2≈3 Pa and is caused by losses in the small version used for “locking” the bactericidal radiation geometric loss values α - screens with openings of small area. The high pressure drop makes serious demands on the air pumping system both in terms of power consumption and the required pressure drop.

It should also be noted that part of the technical solutions proposed in the prototype is fundamentally wrong. In particular, such is the proposal to use an irradiator with a diffusely reflective coating to reduce the concentration of ozone in the air stream due to its photodissociation, for example, from 40 ppm to 2 ppm. Photodissociation of ozone

O3 + hν → O ₂ + O,

hν is a photon with a wavelength of 254 nm (photodissociation cross section σ ~ 1.4 * 10 ^-17 cm ² ) does not lead to a decrease in its concentration due to the fast reverse three-particle process

O + O ₂ + M → O ₃ + M,

M is the third body. Even without taking into account the nitrogen molecule as the third, already M - oxygen molecule, the constant of this reaction ~ 6 * 10 ^-34 cm ⁶ / s is such that the conversion time of the oxygen atom to the ozone molecule is less than 1 ms (0.001 s) when the time of flight through the irradiator> 0.5 s (in reality, the scheme of processes after ozone dissociation is somewhat more complicated, but the result is just that - ozone is restored in the air after photodissociation). This means that the photodissociation of ozone actually leads only to the loss of a photon with a wavelength of 254 nm without a decrease in ozone concentration.

The disadvantages of the prototype should also include the relatively high energy costs for sterilization of the air flow (> 0.5 W / (m ³ / h), as well as the significant cost of the irradiator body, since the material satisfying the requirements of the prototype with an effective diffuse reflectance is preferably> 98 ÷ 99 % has a very high price per unit surface area.In addition, the arrangement of low-pressure mercury lamps described in the prototype is, as will be shown below, substantially non-optimal and leads to a noticeable mu reduce the efficiency of the use of radiation.

The technical result of the claimed invention is to reduce the cost of bactericidal irradiators and a significant increase in their effectiveness, that is, a decrease in their energy consumption.

The technical result is achieved in that in a bactericidal irradiator comprising at least one low-pressure mercury lamp as a source of ultraviolet radiation of the bactericidal range for irradiating the sterilized air stream, an irradiator body with inlet and outlet sections for the sterilized air stream, covering the region irradiated by the ultraviolet radiation source air flow, the main part of the inner surface of which is made diffusely reflecting at least one in The fan for pumping the air flow through the irradiator, the irradiator housing is made of a substantially axisymmetric shape with a low-pressure mercury lamp located close to its axis and geometric parameters in accordance with the following conditions: s / (s + S) <0.1; d / D <0.2, where s is the area of the inner surface of the irradiator without a diffusely reflecting coating, including the inlet and outlet sections of the air flow, S is the area of the inner surface of the irradiator with a diffusely reflecting coating, d is the diameter of the low-pressure mercury lamp, D is characteristic internal transverse dimension (diameter) of the irradiator body.

In the framework of the present invention, a “case” or “case of a bactericidal irradiator” is a shell covering a light source and a sterilized stream, which is made of diffusely reflective material or on the inside of which a diffuse-reflective coating is applied. Thus, a certain case of the irradiator may not be its supporting (structural) element, for which then an additional structural element is used, covering and fixing the case of the bactericidal irradiator described in the claims with a diffusely reflecting inner surface.

The use of an axisymmetric form of the irradiator body with the location of the mercury lamp near its axis allows for the same intensity of the light source to realize a higher intensity (respectively, dose) of bactericidal radiation at the same irradiator performance, that is, its greater efficiency for the following reasons:

раза меньше - соответственно, интенсивность излучения и бактерицидная доза может быть на 13% больше. Для примера из прототипа, когда сечение корпуса облучателя является прямоугольником с отношением сторон 1:2, длина окружности той же площади в

раза меньше - бактерицидная доза на 20% больше. Таким образом, при одной и той же скорости прокачки воздушного потока и одной и той же производительности облучателя генерируемая ртутной лампой бактерицидная доза больше именно в осесимметричном варианте.1. At the same cross-sectional area of the air flow, the circle has a minimum perimeter and, as a result, based on (2), a large radiation intensity is realized in the corresponding cavity. For example, with the same cross-sectional area of a circle and a square, the circumference in

times less - accordingly, the radiation intensity and bactericidal dose can be 13% more. For an example from the prototype, when the cross section of the irradiator body is a rectangle with a 1: 2 aspect ratio, the circumference of the same area in

times less - the bactericidal dose is 20% more. Thus, at the same speed of pumping the air flow and the same irradiator performance, the bactericidal dose generated by the mercury lamp is more precisely in the axisymmetric version.

The smaller perimeter of the cross section of the case of the irradiator can also reduce the area and weight of the diffusely absorbing material necessary for the irradiator, that is, reduce the cost of the irradiator.

The ratio between the area of the diffusely reflecting inner surface of the irradiator and the total area of its inner surface s / (s + S) <0.1, that is, the condition that at least 90% (the "main part") of the inner surface area, including the input and of the outlet cross sections of the air flow is diffusely reflecting, due to the condition for obtaining a sufficiently large gain of bactericidal radiation inside the recirculator, see formula (2). At the same time, unlike the prototype, in the present technical solution, the authors consider the geometric loss value to be “not too small” - in the range of 2–5%, since with a smaller “live section” at the entrance to the region irradiated with bactericidal light and at the exit the air flow from this area sharply increases the pressure drop ΔP required for pumping air and, accordingly, the power consumption for pumping air.

2. The authors of this application have found that the following circumstance is significant: a low-pressure mercury lamp in a cavity of diffusely scattering material with a high effective reflection coefficient is an absorber of its own resonant radiation, reducing its amplification. For the most typical situation, when the lamp length is close to the length of the irradiator (more precisely, to the length of the area irradiated with bactericidal radiation), the fraction of absorbed radiation β is proportional to the ratio of the diameter of the lamp d to the characteristic transverse size of the irradiator D: β = k (d / D), and the coefficient according to the measurements of the authors, the proportionality is 0.5 ÷ 0.7 when the mercury lamp is located near the axis (on the axis) of the axisymmetric cavity of diffusely reflecting material. The condition d / D <0.2 in this case means that the self-absorption losses in the bactericidal emitter (low-pressure mercury lamp) do not exceed 10%, a lower value of such losses is preferable.

For another arrangement of the lamp (s), the absorption loss is greater due to, inter alia, the fact that the fraction of absorbed radiation is proportional to the minimum distance from the axis of the lamp to the surface of the cavity. In particular, for the location of mercury lamps in the corners of the rectangular irradiator casing, a significant part of the light emitted “into the corners” of the irradiator after diffuse scattering (up to 20%) is again absorbed by the lamps. Accordingly, the axisymmetric geometry of the irradiator with a low-pressure mercury lamp located near the axis or on the axis of symmetry is optimal from the point of view of minimizing absorption.

где

- длина разрядного промежутка лампы, L - характерная длина облучаемой области рециркулятора. В последнем случае условие d/D<0,2 модернизируется следующим очевидным образом: (d/D)*(

)<0,2.The losses associated with absorption in a mercury lamp are significant and, in particular, largely determine the minimum diameter of the irradiator casing for relatively low gas flow rates. For example, with an irradiator capacity of 150 m ³ / h (ΔV = 0.042 m ³ / s), the inner diameter of the irradiator body D = 100 mm would seem to be acceptable and corresponds to an air flow rate of 5.3 m / s with a dynamic pressure of about 16 Pa . With a cylindrical shape of an irradiator with a length L = 150 cm, when optimizing the gas-dynamic circuit, the pressure drop can exceed the dynamic pressure by only 2 ÷ 2.5 times (see below) and be ΔР ~ 40 Pa, which corresponds to the power consumption for pumping air W _PR = ΔV * ΔP / η _V ~ 5 W. To a first approximation, the geometric losses for the indicated form of the irradiator with the “open” inlet and outlet of the air flow are α ≈ D / (2L + D) ~ 3% and are quite small. At the same time, the self-absorption losses in a mercury lamp with a wide diameter of 19 mm are β≈0.6 (d / D) ~ 11% and significantly exceed other types of losses even for R = 95% and especially for R> 95%. Thus, the inner diameter of the irradiator ≤120 ÷ 150 mm is not advisable even for small air flow rates, or it is preferable to use special mercury lamps with a small diameter of ~ 10 mm (this may reduce its life) or lamps with a length that is significantly less than the length of the recirculator body. In the latter case, an additional factor appears for losses associated with self-absorption of resonant radiation in a low-pressure mercury lamp located in the cavity of the irradiator with a surface of diffusely scattering material

Where

is the length of the discharge gap of the lamp, L is the characteristic length of the irradiated region of the recirculator. In the latter case, the condition d / D <0.2 is modernized as follows: (d / D) * (

) <0.2.

With a typical diameter of a low-pressure mercury lamp of 15 ÷ 35 mm and a transverse size (diameter) of the irradiator for an air flow of 0.1 ÷ 5 thousand cubic meters per hour 150 ÷ 600 mm, the losses associated with absorption in the lamp are 3 ÷ 7 (10) % and can be comparable with geometric losses. Note that as the diameter of the irradiator body increases, the losses associated with self-absorption in the lamp tend to decrease, and the geometric losses increase and, therefore, the total losses in the irradiator not related to reflection in practical cases are ≥4 ÷ 6%. This, in particular, means that less exotic and expensive (or in comparison with the prototype) materials or coatings, in particular fluoroplast-4 and its copolymers transparent in the region of 254 nm, can be effectively used as a diffusely reflecting inner surface of the irradiator. As established by the authors, fluoroplast-4 (Teflon, PTFE) already with a thickness of 1.5 ÷ 2 mm provides an effective diffuse reflection coefficient> 88 ÷ 90%, and with a slightly larger thickness, a value of R ~ 92 ÷ 94% is achievable. As a result, the gain of the radiation incident on the surface of the irradiator N ~ 8 ÷ 12 can be ensured and, on the whole, the intensity of bactericidal radiation in the cavity increases by 15 ÷ 20 times due to an additional factor (1 + R) with respect to I _P.

For the cylindrical geometry of an irradiator with a diameter D and length L, when the side surface of the cylinder is diffusely reflective, and the inlet and outlet sections of the air flow are a circle of diameter D on which there is no reflection of radiation, the geometric loss in the first approximation is the ratio of the corresponding areas: α = D / (D + 2L), here the smallness of the diameter of the mercury lamp is taken into account in comparison with the diameter of the irradiator. With a more accurate calculation, it is necessary to calculate the corresponding solid angles taking into account the radiation pattern of the diffuse reflection and the actual geometry of the irradiator, however, as a first approximation, the above relation gives fairly correct results. Hence, the condition for the smallness of the corresponding losses takes the form L / D> (n-1) / 2, where 1 / n is the geometric loss. For geometric losses of 15%, from here we get the condition L / D> 3, for L / D> 5 geometric losses <10%, these criteria are accepted by the authors of this technical solution.

As mentioned above, the diameter of the irradiator should not be too small and increases, including with increasing productivity of the recirculator, since the pressure loss during pumping (without a dust filter) is ~ (ΔV) ³ / D ⁴ . In this case, for the cylindrical geometry of the irradiator, reasonably small geometric losses can be realized with a significant increase in the length of the recirculator, that is, with a significant increase in its dimensions, weight and, therefore, cost, which is not desirable. Note that for real parameters of the irradiator, the air flow in it is turbulent and, in itself, an increase in the length of the irradiator body, the inner surface of which is made of a fluoroplastic material with low friction losses, slightly increases the pressure drop required for pumping air even at L / D ~ 10 ÷ 15.

In order to ensure a sufficiently small value of geometric losses with a moderate length of the irradiator body in one embodiment of the claimed technical solution, the cross-sectional area (diameter) of the irradiator body at the inlet and / or outlet of the air flow from the irradiated region is less than the cross-sectional area (diameter) the main body of the irradiator. Such an irradiator geometry can be realized through the use of a confuser-diffuser system, and the expanding (narrowing) parts of the gas-dynamic circuit also have a diffusely reflective coating or are made of diffusely reflective material. With smooth transitions from a larger cross-sectional diameter to a smaller (and vice versa), the irradiator remains compact enough, the geometric radiation loss is significantly reduced already for the ratio of the areas at the input / output of the irradiator and its main part 0.5 ÷ 0.6 (the preferred area ratio < 0.7), the additional pressure loss may be large and comparable to the dynamic pressure of the airflow ρν ^2/2 (in the general case, the pressure losses are usually expressed in terms of dynamic pressure: .DELTA.P = ζ * ρν ^2/2, ζ - the numerical coefficients customer). That is, for a correctly configured confuser-diffuser system ζ ~ 1 (and even ζ <1), which at a typical flow velocity in the main irradiator region of ~ 5 m / s corresponds to ΔР ~ 15 Pa. As a result, with a typical irradiator performance of 0.03 ÷ 1.5 m ³ / s (100 ÷ 5000 m ³ / h), the considered application of the diffuser-confuser system requires additional power for pumping 1.5 ÷ 75 W. This amount of additional energy consumption for pumping air may be acceptable, since the power consumed by the bactericidal light source can be reduced by a significantly larger amount.

The flow velocity in the main part of the irradiator 3 ÷ 6 m / s is preferable, since the power consumption for pumping air may be relatively small, and the dimensions of the irradiator remain acceptable. For example, with an irradiator capacity ΔV = 3000 m ³ / h (0.83 m ³ / s), the diameter of the main part of the irradiator 500 mm corresponds to an air flow rate of 4.2 m / s and a dynamic head of ~ 10 Pa. It is necessary to emphasize the importance of optimizing the gas-dynamic circuit in the claimed technical solution, since due to the multiple reduction in the cost of power for bactericidal radiation, the share of the cost of power for pumping becomes significant.

For example, in well-known analogues with a capacity of 3000 m ³ / h, the power consumption for radiation is> 2000 W, and for pumping the air flow ~ 150 ÷ 200 W, and in this sense, changing the power spent on pumping in the range of 100 ÷ 250 W is not important, since the power consumed as a whole varies in the range of ± 2 ÷ 3%. At the same time, with a decrease in the required bactericidal radiation power of only 8 ÷ 10 times, the same change in pumping power will lead to a change in the power consumed by the bactericidal irradiator within ± 15 ÷ 20% or up to one and a half times. In particular, the optimization element of the gas-dynamic contour of the irradiator can be the implementation of a smoothly narrowing section of the air flow at the inlet of the irradiator and / or its smooth expansion at the exit of the irradiator, which can significantly reduce the corresponding pressure loss ([15]: I. Idelchik hydraulic resistance. M.: Mechanical Engineering, 1992 - 672 s).

An embodiment of the claimed invention is shown in FIG. 1, here 1 is the source of bactericidal radiation (a low-pressure mercury lamp), 2 is the illuminator body with an expanding part 3 and a tapering part 4, an air flow inlet (air inlet in Fig. 1) into its sterilization area 5 and exit 6 from it (Exit in Fig. 1). Accordingly, in FIG. 1, the inner surface of the irradiator between sections 5 and 6 of area S is diffusely reflective, and the area of the inner surface of the irradiator without diffusely reflecting coating s is the sum of the areas of sections 5 and 6. Here it is necessary to indicate that the total area of the inner surface of the irradiator can significantly exceed S - for example , "Upstream" in the inlet area of the irradiator 7 can be placed a fan, dust filters, etc. This area 7 can be performed with or without diffuse reflective coating or not from diffusely reflecting radiation of the material, in the latter case, it no longer participates in the bactericidal irradiation of the air flow.

Note also that in FIG. Figure 1 does not show the power source of a low-pressure mercury lamp, a fan, systems for fixing the lamp in the body of the irradiator and blocking the exit of bactericidal radiation outside the irradiator (see below), which are usually used as part of the irradiator (recirculator), additional dust filters and other filters used in some irradiators etc. and the like, since these components of the irradiator are not the subject of the claimed technical solution, with the exception of the options described below. At the same time, the irradiator elements located inside its region bounded by the diffusely reflective coating are also preferably diffusely reflective — for example, the lamp fixing elements in the irradiator casing can be made of Teflon or made with a diffusely reflective coating. Similarly, the electrode nodes of a mercury lamp can be made with a diffusely reflective coating or “closed” with a Teflon tube of the corresponding diameter and thickness.

As indicated above, a material that provides a high diffuse reflection coefficient in the bactericidal range of the spectrum at a moderate cost and thickness is fluoroplast-4 (Teflon, PTFE) and some of its copolymers. Known and specified in the prototype expanded fluoroplastic (e-PTFE) provides a slightly larger diffuse reflectance with a smaller thickness and can be used in the claimed technical solution, however, the cost of such material is significantly higher. In addition, with real light losses in the irradiator, including, inter alia, its geometry and absorption in the RLND, the value of the diffuse reflection coefficient R≈98 ÷ 99% and higher is practically not required. Other materials are also known, as a rule, on the basis of fluoroplastic or its analogues, for example, Spectralon of a company from the USA LABSPHERE, INC., Reference material WS-2 from the Dutch company Avantes BV, etc.

A high diffuse reflectance can also be achieved by suitable coatings, for example based on powders of magnesium oxide (MgO) or barium sulfate (BaSO ₄ ), this type of coating is offered, for example, by a company from the USA LABSPHERE, INC. (https://www.labsphere.com/labsphere-products-solutions/materials-coatings-2/) Here, the irradiator housing can be made of standard structural material (from stainless steel, aluminum or an aluminum alloy to various plastics), to the inner the surface of which is coated with an appropriate diffuse-reflective coating.

In addition to the well-known diffuse-reflective coatings, similar surface properties (high diffuse reflection coefficient) can be realized due to multiple light rescattering by variations of the refractive index in a medium transparent to radiation (that is, in non-absorbing radiation). Such a medium can be obtained in a coating, which is a binder (matrix) transparent to radiation of the bactericidal range, with particles distributed in it which are also transparent to radiation of the bactericidal range, with a refractive index different from that of the binder. These particles can be, for example, silicon oxides SiO ₂ and / or aluminum oxides Al ₂ O ₃ and / or magnesium oxide MgO. As a binder, for example, siliconized water glass Na ₂ O⋅nSiO ₂ can be used.

In order to implement a coating of reasonable (moderate) thickness according to this option, it is necessary to create a sufficient number of media interfaces with different refractive indices, for which it is advisable to use small particles, preferably not more than 30 ÷ 50 microns. In this case, the coating can be applied, in particular, by spraying, such as liquid paint (the binder and micropowder are pre-mixed with water to reduce viscosity, then after application to the surface the water evaporates during drying), and even with a thickness of 1 mm this coating provides a diffuse reflection coefficient 90-95% for λ ~ 250 nm. It is possible to additionally reduce the thickness of the described coating and increase the effective reflection coefficient if hollow microspheres, for example aluminosilicate microspheres, are used as particles, since scattering at the interface with air corresponds to the maximum relative refractive index and the efficiency of such scattering is maximum.

A variant of the irradiator, when a diffusely reflecting coating 8 is applied to the inner surface of its body, is shown in FIG. 2, the remaining symbols coincide with FIG. one.

In order to further improve the uniformity of the light field in the volume of the irradiator, the inner surface of its body can be made wavy in the circumferential direction.

When using an irradiator body of a substantially elongated cylindrical shape, applying a diffusely reflective coating to its inner surface is a significant difficulty. In order to simplify the solution of this problem, the authors propose, in one embodiment of the claimed technical solution, to make the irradiator body consisting of at least two independently manufactured parts, which, for example, can be half of the body “cut” along its generatrix (along the axis of the sterilized flow ), one of the possible variants of such a technical solution with an undulating inner circumference of the irradiator is shown in FIG. 3 (in the manufacture of an irradiator from a sheet or by extrusion, the wall thickness of the casing may be constant), the designations coincide with the previous ones. The application of both known diffuse-reflective materials and the transparent coating proposed above with scattering microparticles on such “open” surfaces is not a problem, and then parts of the irradiator body are connected into a single unit, for example, by means of power engagement, using clamps or special flanges with bolted connection. The body parts (external to the bactericidal radiation parts of the body) of the irradiator can be made, including, of aluminum (aluminum alloy) or plastic, for example by extrusion or casting.

As mentioned above, a decrease in geometric losses increases the luminous flux inside the irradiator with a diffusely scattering inner surface (which is an important advantage), but at the same time, gas-dynamic losses almost always increase to some extent (the ζ coefficient increases) and the power consumption for pumping the air flow increases (which is a significant drawback), an example of such a situation is the prototype. The authors of the claimed technical solution in one of the options for its implementation propose to use to reduce geometric losses that component of the bactericidal irradiator, which is necessarily present in its gas-dynamic circuit - a fan. It is proposed that at least a part of the surface of the fan (primarily its blades), facing the irradiated region of the air flow, diffusely reflects the bactericidal radiation of the ultraviolet range. For this purpose, the fan blades (as well as its central part) can be made of Teflon or its copolymers, or a diffusely reflective coating can be applied to the corresponding surfaces.

Possible (but not the only) options for implementing the proposed technical solution are shown in FIG. 4, in which 9 is a fan used for pumping air flow, 10 is its diffusely reflecting surface, the rest of the designations coincide with those shown in FIG. 1-3. A fan with a diffusely reflective surface coating can be installed on the side of the incoming air stream (Fig. 4a), on the side of the outgoing air stream (Fig. 4b), as well as on both sides (Fig. 4 c-d). The size (diameter) of the fan blades may be close to the diameter of the main part of the irradiator body (Fig. 4d) and may differ significantly from it if the fan is located in the expanding or tapering part of the irradiator body (Fig. 4c).

In this case, without introducing additional gas-dynamic losses, the geometric radiation losses in the corresponding section (input and / or output) can be significantly reduced: according to the results of the authors' measurements, the effective cross section through which bactericidal light can go beyond the irradiated region can be reduced by up to three times and even more depending on the specific geometry and number of fan blades. As a result, for the cylindrical geometry of the irradiator, as shown in FIG. 4d (without a confuser-diffuser system, which simplifies the design and manufacturability of the irradiator), cL = 100 cm D = 15 cm when installing modernized fans in the input and output of the irradiator according to the proposed option, when the effective cross section of geometric losses for radiation is reduced threefold, geometric losses can significantly decrease: from α = D / (D + 2L) = 7.0% to α = D / (D + 6L) = 2.1%. As a result, the intensity of bactericidal radiation in the irradiator can increase by 1.5-2 times.

For closed irradiators (recirculators) that work in the presence of people, it is fundamentally important and necessary to block bactericidal radiation so that it does not go out into the open - beyond the recirculator. As a rule, this kind of radiation blocking is performed due to inclined gratings-blinds, a typical example is the bactericidal recirculator Aerolit-400 manufactured by LIT ([2]). However, in a well-known version of this kind of technical solutions lead to a sharp increase in gas-dynamic losses: for inclined gratings with a geometry that provides effective radiation blocking, the coefficient ζ> 1 (usually even ζ> 4 ÷ 5). Significantly reduce pressure losses can be in various ways, for example, as the authors suggest, by turning the air flow at the inlet and outlet of the irradiator with appropriate ducts, the inner surface of the duct made of a material that absorbs ultraviolet radiation of the bactericidal range. The appropriate angle of rotation of the air flow Φ is at least 60 °, (preferably from 80 ÷ 90 °), and the preferred length of the radiation-absorbing region is such that the radiation hits the absorbing surface twice — in this case, the bactericidal radiation is guaranteed not to go beyond the irradiator. The preferred radius of rotation of the air flow r is determined by the condition of small additional gas-dynamic losses, already for r = D (D is the diameter of the air flow at the entrance to the turn) and sufficiently smooth walls ζ <1 (even ζ <0.3 for a typical Reynolds number of the air flow in irradiators ~ 3 * 10 ⁴ ÷ 3 * 10 ⁵ corresponding to the turbulent flow regime [15]). In FIG. 5 shows an implementation option of the proposed solution, here 11 is the air ducts with an air stream rotation at an angle Ф = 90 ° with the inner surface of a material absorbing bactericidal radiation, the air stream inlet is made with smooth narrowing 12 to further reduce gas-dynamic losses, the rest of the notation coincides with the previous ones.

It is important to indicate that in the preferred embodiment of the claimed technical solution, an ozone-free low-pressure mercury lamp or a lamp with substantially reduced power at a second resonant wavelength of a mercury atom of 185 nm is used. This is due to the fact that with a potentially significant increase in the luminous flux inside the irradiator - N ~ 10 times or more - the absorption of bactericidal radiation by the ozone generated by such a lamp significantly increases losses and reduces the efficiency of using an irradiator with a high diffuse scattering coefficient. In fact, with the irradiator’s size (diameter) D, the characteristic path length of the bactericidal radiation in the irradiator is ~ ND and the condition for small losses in ozone absorption has the form σ [O ₃ ] ND≤0.01 ÷ 0.02 (assuming allowable absorption losses in irradiator 1 ÷ 2%). Hence, for a sufficiently productive bactericidal irradiator with D = 20–50 cm, we obtain the following restriction on the concentration of ozone: [О ₃ ] _max <0.015 / (σND) ~ 2 * 10 ¹² cm ^-3 or ~ 0.1 ppm, which is close to the MPC ozone.

Since the absorption in air of one photon with a wavelength of 185 nm creates two ozone molecules and these molecules in the irradiator die only due to interaction with microorganisms and chemical impurities in air, the limitation on the permissible radiation power of a lamp at this wavelength has the following form: W ₁₈₅ ≈ [О ₃ ] ΔVε / 2 <[О ₃ ] _max ΔVε / 2 ~ 1 W for a volumetric air flow rate of 1 m ³ / s, ε ≈ 10 ^-18 J is the quantum energy with a wavelength of 185 nm. At the same time, for the indicated flow rate at the same bactericidal radiation amplification value N = 10, the light power at a wavelength of 254 nm, required for a degree of sterilization of Staphylococcus aureus 99.9%, is W ₂₅₄ > EΔV / N ~ 40 W.

Thus, the ratio of the power of bactericidal (254 nm) and vacuum (185 nm) radiation RLND in the framework of this technical solution should be> 40 (if necessary, ensure sterilization of more resistant to bactericidal radiation microorganisms, that is, with a larger value of E - and more than 100) Moreover, for the “ozone” RLND, the indicated ratio is usually ~ 5–6. We emphasize that in the inventive irradiator, the ozone-free mercury lamp is used not because ozone is harmful in itself - this problem is solved by using special filters at the outlet of the irradiator, but because ozone significantly reduces the gain in bactericidal radiation intensity in the irradiator with a high coefficient diffuse reflection.

The claimed technical solution can be implemented with any mercury lamp of low pressure, however, in the preferred embodiment, the amalgam RLND is used, which, as indicated above, provides significant environmental advantages and the subsequent disposal of used lamps. In this case, the source of mercury vapor during operation of the lamp is at least one amalgam source of mercury atoms located on the inner surface of the lamp (for lamps of considerable length, several amalgam sources can be used, which are a foil of the corresponding mercury alloy with a diameter of usually 5 ÷ 8 mm) . The temperature at which the concentration of mercury vapor in the lamp is optimal ~ (1 ÷ 2) * 10 ¹⁴ cm ^-3 is usually 100 ÷ 130 ° C depending on the specific composition of the amalgam, and for a lamp inoperative (at room temperature), the concentration mercury vapor in it is negligible and does not pose a threat in case of violation of the tightness of the lamp. If the lamp loses tightness during operation, the discharge power is automatically turned off (power supply option) and the lamp cools quickly. At the same time, the volume of the working lamp contains no more than 6 * 10 ¹⁶ mercury atoms (for a lamp volume of 300 cm ³ , for example, for a lamp with an outer diameter of 19 mm, length 150 cm), that is, the mass of "free" mercury in the lamp is not more than 20 μg which corresponds to the maximum concentration limit in the air volume of ~ 60 m ³ . As a result, a short ventilation of the room is quite sufficient even if the amalgam lamp loses its tightness during operation.

Amalgam RLNDs have the following feature: it is rather difficult for them to realize low radiation power at high efficiency, since the linear power input and, accordingly, radiation should be large enough to ensure that the temperature of the lamp walls is not less than the working temperature of the amalgam. At the same time, with the claimed technical solution for the irradiator performance ΔV = 0.08 m ³ / s (300 m ³ / h), bactericidal radiation power up to 3 ÷ 4 W is quite sufficient. Then, for a typical linear output power of amalgam lamps from 0.5 W / cm, the length of the positive column is 6 ÷ 8 cm, but in this case the lamp efficiency will decrease by at least half, since the near-electrode voltage drop of 12-14 V will exceed the voltage of the positive discharge column in the lamp. Thus, the length of the interelectrode distance in the amalgam RLND, which is preferable for high efficiency, is> 30–40 cm. A decrease in the linear radiation power due to a significant decrease in the diameter of the lamp, as a rule, leads to a rapid drop in its life.

To solve the problem of reducing the power of amalgam RLND while maintaining its high efficiency, the authors propose to take into account that a temperature of 100 ÷ 120 ° C is necessary only in the area of the amalgam spot, and the rest of the lamp surface may have a temperature of 45 ÷ 50 ° C, for which the concentration of saturated mercury vapor already exceeds the optimum value for the lamp (the concentration of saturated mercury vapor 10 ¹⁴ cm ^-3 corresponds to a temperature of 31 ÷ 32 ° C, twice as much concentration to a temperature of about 40 ° C). To maintain the indicated wall temperature, a multiple times lower linear power in the positive discharge column is sufficient than for standard amalgam RLNDs, which allows several times to increase the positive column length for a lamp of the same radiation power and significantly increase its efficiency. However, in this case, special heating of the portion of the inner surface of the lamp with an amalgam "spot" is necessary, for which a low-pressure mercury lamp has at least one additional heating source of at least one amalgam source located on the outer surface of the lamp in the area of the amalgam source. As the calculations and experiments of the authors showed, with a characteristic amalgam spot diameter of 5 ÷ 8 mm and a quartz glass lamp wall thickness of ~ 1.5 mm, the heat dissipation power of ~ 0.3 ÷ 0.4 W is quite enough to provide the required temperature, i.e. the energy consumption of an additional source Amalgam heating is small and practically does not reduce the efficiency of even a low-power amalgam lamp.

In a preferred embodiment, the amalgam RLND with additional heating of the amalgam includes a flask made of a material that is transparent to the radiation of a mercury lamp, enclosing the lamp, and, in an optimal embodiment, the flask is sealed. In this case, the air flow through the irradiator practically does not cool the lamp, which allows to further reduce the required linear heat dissipation power and further increase the efficiency of the low-power amalgam lamp. For a sealed additional bulb filled with gas with low thermal conductivity (for example, xenon) or evacuated to low pressure, the heat transfer from the walls of the lamp is additionally hampered, which makes it possible to further reduce the linear radiation power of such a lamp and increase its efficiency.

One possible implementation is described below and is shown in FIG. 6. The mercury lamp (emitter) is made by standard technology and is a cylinder 13, preferably a small diameter, for example 12 ÷ 15 mm, made of quartz glass with electrodes 14 placed at the ends of the tube (this is actually an electrode assembly with complex electrodes, for example, trifilar and etc.). An amalgam source of mercury vapor 15 with a characteristic diameter of 5–8 mm is located on the inner surface of the lamp, for example, in its central part. On the outside of the lamp opposite the amalgam, separated from it only by the wall, a local heating source (heat release) 16, for example, ohmic heating, is additional to the heat generated by the discharge. Coaxial with the lamp tube is a tube (“bulb”) made of silica glass of larger diameter 17, for example with an inner diameter of 22 ÷ 25 mm and a wall thickness of -1.5 mm. Using the flanges 18-19 located at the ends of this bulb, it tightly covers the emitter lamp. The gap between the outer surface of the lamp and the inner surface of the bulb 20 can be pumped out to low pressure ("vacuum") to minimize heat transfer between the walls of the lamp and bulb, and is also filled with air or gas with lower thermal conductivity, for example, one of the heavy inert gases.

When the lamp is turned on in parallel with the heating of the electrodes and / or the initial stage of the discharge in the buffer gas, an additional heat source is used to heat up the lamp section on which the amalgam source of mercury atoms is located. An independent power source can be used for this, as well as, in some cases, an additional heat source can be included in the main discharge circuit between the lamp electrodes, the current of which can already be enough for an additional ohmic heat source resistance of ~ 3 Ohms.

As a result, as shown by the experiments of the authors, it is possible to reduce the discharge current by 4–7 times, for example, from ~ 1.2 A to ~ 0.2 A in an amalgam mercury lamp with a diameter of 15 mm, while the field strength in the positive column of the discharge increases significantly. Similarly, a high efficiency amalgam RLND was obtained at a low current density and for lamps with a larger diameter. In particular, for the geometry described above and the gap between the lamp (∅15 mm) and the bulb (internal ∅22 mm, wall thickness 1.5 mm) filled with xenon of atmospheric pressure, a radiation power of about 8-9 W was realized at an interelectrode distance of 780 mm and technical efficiency ~ 45%, that is, for the power consumed by the lamp about 17 ÷ 18 watts.

The power spent on heating the amalgam in the conditions described was about 0.3 W — it is easy to realize due to ohmic heating and the influence of the corresponding energy costs on the efficiency of the emitter is minimal. Moreover, with a lamp current of ~ 0.3 A, the resistance of an ohmic heater ~ 5 Ohms in the main discharge circuit is already sufficient for additional heating of the amalgam, at the same time, the resistance of the positive column is up to 500 Ohms (with a decrease in current, the discharge voltage increases) and losses Amalgams on heating are <1%.

In some cases, the necessary amalgam temperature can also be obtained by placing the amalgam spot near (at an appropriate distance) from the electrodes of the main discharge, since the temperature of the used heating electrodes exceeds 650-700 ° C and, therefore, at a certain distance from them, the temperature is 100-130 ° C. This distance for a specific geometry of the lamp can be determined experimentally.

The reduction in linear power is provided by reducing the discharge current and, accordingly, the concentration of electrons and positive ions in the discharge. This makes it possible to increase both the efficiency of amalgam RLND (the temperature of the electron gas and the excitation efficiency of mercury atoms increase, the influence of electronic quenching decreases) and its life by reducing the frequency of ion bombardment of the lamp walls, which reduces its transparency for bactericidal radiation.

The increase in the efficiency and resource of the described amalgam RLND leads, among other things, to a significant reduction in operating costs for the bactericidal irradiator claimed by the authors, especially taking into account the fact that the main components of bactericidal irradiators of moderate performance from the fan to the radiator power supply have a resource several times longer, than the resource of modern amalgam lamps ~ 12 thousand hours (replaceable dust filters, of course, have a relatively low resource, but also low cost at replacement height).

For a number of microorganisms, irradiation with broadband or multi-frequency bactericidal radiation provides a higher degree of sterilization at the same total dose ([3]). In order to realize the indicated possibility, in one of the variants of the claimed technical solution, along with a low-pressure mercury lamp, at least one bactericidal ultraviolet radiation source is an excimer lamp. Preferred options are lamps on transitions of XeBr * molecules (~ 280 nm), KrCl * (~ 222 nm), it is also possible to use transitions on bands of KrF * (~ 248 nm), XeI * (~ 253 nm) and close to 254 nm Cl2 * (~ 258 nm).

An important property of excimer lamp media is the absence of any noticeable absorption of both intrinsic radiation and the absorption of radiation from a mercury lamp at a wavelength of 254 nm; similarly, a mercury lamp does not absorb radiation from excimer lamps. As a result, an excimer lamp does not introduce additional losses into the volume of a bactericidal irradiator with a diffusely reflecting inner surface, does not reduce the efficiency of using RLND, and, in turn, can be placed in almost any area of such an irradiator.

Diffuse reflecting materials and coatings have a fairly stable reflection coefficient in a wide range of wavelengths, and in many cases the reflection coefficient of such materials increases with increasing wavelength in the region of 250–300 nm, which is consistent with the authors' data. As a result, taking into account the absence of absorption in the volume of the irradiator, for the XeBr * excimer lamp, the effective radiation gain in the inventive irradiator is much higher than for RLND, taking into account the factor (1 + R), gain values of 30 ÷ 35 and higher are achieved. In fact, this means a significantly greater efficiency in the use of light of the indicated excimer molecule in comparison with the radiation of the resonance mercury line of 254 nm, which increases the synergistic effect when sterilizing the air stream with such multi-frequency radiation. As a result, the radiation power of an excimer lamp and the power consumption of such a lamp can be significantly reduced. As a result, with comparable energy consumption of such a bactericidal irradiator with several different emitters, the degree of sterilization can be increased, which is especially important for medical facilities (hospital wards, operating rooms), rooms with children (kindergartens, schools), etc.

Transparent flasks that enclose RLND are known and widely used, for example, in bactericidal water treatment systems and protect the lamp surface from contamination as a protective case, also performing the function of a heat insulator from a sufficiently cold water stream, while the power released in the discharge itself is sufficient to heat the surface lamps to the temperature required for the amalgam. An additional source for heating the amalgam was proposed in US 2004/0232846 ([16]) primarily to ensure the optimal temperature regime of the amalgam specifically when the temperature of the treated stream changes, for example, if the temperature of the irradiated water changes from cold to hot. It should be noted that in practice such situations practically do not arise, since the cleaning systems are very specialized, and when sterilizing air in rooms, its temperature generally changes slightly. In the case of [16], the heat dissipation power in the lamp is quite high and, accordingly, the heat-insulating properties of the gap between two walls (lamps and flasks) are not regulated in any way. Efficiency and lamp life also do not change. In addition, we point out that modern amalgams provide a fairly stable concentration of mercury vapor in a wide temperature range, from ~ 100 ° C to ~ 140 ° C, which solves the problem formulated in [16] without the use of additional sources of heating of the amalgam and which is impossible in the claimed technical the solution when the insulating flask is used in the processing of the air flow. That is, the accompanying introduction of additional (to the heat in the discharge) heating of the amalgam and the heat insulating flask, a sharp, multiple decrease in the discharge current is a fundamentally important difference between the authors proposed option, which increases the efficiency and service life of the amalgam RLND in the composition of the bactericidal irradiator.

It is important to indicate that the authors proposed option for implementing amalgam RLND with low linear power is of practical interest specifically for the bactericidal irradiator, the casing of which is made according to the claimed technical solution and provides a sharp increase in bactericidal efficiency, which allows a multiple decrease in the power of the bactericidal radiation source. In almost all other cases, the goal of amalgam RLND manufacturers is to increase the linear power of this light source, and therefore technical solutions are proposed for additional cooling (rather than heating) of the amalgam.

In addition, the authors found that the absorption of intrinsic resonance radiation by a low-pressure mercury lamp significantly affects the radiation intensity in a cavity with a diffusely reflecting inner surface, which limits the ratio of the size of the lamp to the irradiator, and also determines the optimal irradiator geometry and the location of the RLND in it.

(j - плотность тока разряда), то есть при уменьшении тока в 4 раза концентрация частиц, вызывающих деградацию лампы, падает приблизительно вдвое.The use of the substantially diffuse-reflecting surface of the bactericidal irradiator housing allows, as shown by the authors, also to drastically reduce the required radiation power of an excimer lamp when it is used as an additional source of bactericidal ultraviolet light. Reducing the radiation power for excimer lamps can preferably be achieved by reducing the discharge current without using the technical solutions described above for amalgam RLND (additional heat source, thermal insulation). This is due to the fact that even at room temperature the saturated vapor pressure of typical halogen-containing molecules introduced into the working medium (Br ₂ , I ₂ , IBr, Cl2, etc.) is sufficient for the efficient operation of an excimer lamp. As is known and also confirmed by the authors of the application, when the discharge current decreases, the excimer lamp efficiency increases. In addition, with a decrease in the power input and discharge current and, as a consequence, a decrease in the concentration of reactive atoms and halogen ions, an increase in the lifetime of an excimer lamp is very likely. Note that the concentration of active particles in a glow or capacitive discharge plasma for a constant composition of the gas mixture is proportional to a first approximation

(j is the discharge current density), i.e., when the current is reduced by a factor of 4, the concentration of particles causing lamp degradation drops by about half.

Further, since the field strength in the discharge of an excimer lamp weakly depends on the current (on the electron concentration) and is determined primarily by the composition of the gas mixture, a decrease in the discharge current means a corresponding increase in the resistance of the discharge gap. This, in particular, makes it possible to efficiently use capacitive discharge for low-current excimer lamps ([5]), which provides a higher service life of excimer lamps, at least for iodine and bromine-containing halides.

Further, the technical solution is illustrated using examples, which however it is not limited.

A low-pressure mercury-free amalgam mercury lamp with a diameter of 15 mm and an interelectrode length of 780 mm was used. An amalgam "spot" with a diameter of about 7 mm was located on the inner surface of the lamp near its middle. In the normal mode of operation, the output to which took place in ~ 3 minutes, the power consumed from the network was ≈140 W at a bactericidal radiation power at a wavelength of 253.7 nm of about 44 W, and the technical efficiency was about 31.5%. The current of the lamp power supply could be modified (decreased) using a special control panel, which allowed varying the power of ultraviolet radiation within 35 ÷ 44 W; most of the experiments were carried out with a bactericidal radiation power of 40 W. The radiation power of the lamp at different discharge powers was determined in the absence of a housing (in free space) using the well-known Keitz formula.

The excimer lamp was a quartz cylinder with an external diameter of 15 mm and an internal diameter of 12.6 mm emitting in the BX band of the XeBr * molecule with a maximum of about 280 nm. The lamp was excited by a low-current glow discharge, the interelectrode distance was 60 cm, and due to a change in the discharge current, the radiation power of the excimer lamp could vary within 0 (1) ÷ 20 W. The lamp mount inside the irradiator was made of Teflon, the electrode assemblies were also closed with Teflon tubes.

In most experiments, the body of the irradiator was a tube of different diameters 1000 mm long, made of 3 mm thick Teflon (PTFE) sheet; the lamp was located on the axis of the housing symmetrically with respect to its entrance and exit; the lamp was mounted in Teflon; the electrode assemblies of the lamp were also closed with Teflon tubes.

The radiation intensity on the surface of the housing could be separately measured by a special radiation receiver with a diameter of 4 mm with a cosine corrector inserted into the hole in the housing with a diameter of 6 mm. Such holes were made in various parts of the casing and, without a radiation receiver, were closed with special Teflon plugs to minimize the effect on the distribution of light fluxes in the irradiator casing. Due to spectral decomposition in the receiver, the intensity of the bactericidal radiation incident on the surface of the irradiator casing could be measured separately at the wavelength of the resonance radiation of the mercury atom and in the radiation band of the XeBr * excimer molecule, and then the obtained values were averaged over all positions of the receiver.

Air flow was directed into the irradiator using fans with different air flow rates. In part of the experiments, the corresponding diffusers / confusers in accordance with FIG. 2.

1. With an inner diameter of the cylindrical case of the irradiator 152 mm (d / D ≈ 10) and a radiation power of the lamp of about 40 W, the intensity of the light flux incident on the surface of the irradiator increased ~ 7 times compared with the case of an open lamp (≈ 9 mW / cm ² ) . Accordingly, the radiation intensity inside the irradiator increased ~ 13 times taking into account the factor (1 + R), R ~ 0.9. At the same time, the power consumption for pumping the air flow with an air flow of 300 m ³ / h was about 7 W, and the total power consumption was up to 150 W.

The bactericidal dose at this rate was approximately (assuming uniformity of light over the volume of the irradiator): Q = 63 [mW / cm ² ] * 1.9 * 1500π [cm ² ] * 3600 [s] / 300 [m ³ ] ≈ 6700 J / m ³ , the second factor is the factor (1 + R), the third is the area of the inner surface of the irradiator. This is many times more than the bactericidal dose that would be created in a standard irradiator-recirculator with aluminum or stainless steel walls: assuming a bactericidal flux utilization coefficient K _f = 0.5 high enough for such closed irradiators, we get Q = 40 [W ] * 3600 [s] 0.5 / 300 [m ³ ] = 240 J / m ³ , which is not enough even for high-quality sterilization of Staphylococcus aureus (the lamp power required for the degree of sterilization of 99.9% is one and a half times greater - about 60 W )

In the manufacture of a 1 mm-thick Teflon-type irradiator similar in geometry, the gain in the intensity of the light flux incident on the irradiator surface was ~ 3.5 times compared with the case of an open lamp. A much smaller gain is due to the fact that the diffuse reflection in Teflon and its copolymers (including expanded Teflon) is three-dimensional in nature and, therefore, to ensure a sufficiently high effective reflection coefficient, a layer of such material of sufficient thickness is required. According to our measurements, for an expanded fluoroplastic (Teflon), a layer thickness of 1 mm is already sufficient; for "ordinary" Teflon, a layer thickness of ≥2 mm is preferred. Note that with the same mechanical and electrophysical properties of fluoroplastics made using different technologies, the teflon layer thickness required for the purposes of the claimed technical solution can vary significantly, for a specific manufacturing technology the required layer thickness is determined experimentally. It is also useful to additionally indicate the importance of controlling the purity of the used Teflon, since in the presence of impurities absorbing in the bactericidal region of the spectrum (“dirt” and absorbing copolymers, as well as other absorbing impurities), it is radiation absorption that limits the possible thickness of the material of the irradiator body. For example, with a radiation absorption coefficient at 254 nm δ = 10 cm ^-1 (the absorption coefficient can be several orders of magnitude higher), the use of a layer of such a material with a thickness> 1 mm no longer makes sense. The same remark applies to the cleanliness and technology of applying diffusely reflective coatings.

When the inner diameter of the cylindrical body of the irradiator is 90 mm (d / D ≈ 6), the intensity of the light flux incident on the surface of the irradiator additionally increased to ≈ 95 mW / cm ² - by ~ 1.5 times in comparison with the intensity on the surface of the irradiator with an internal diameter of 152 mm However, in this case, the radius of the irradiator decreased by ≈1.7 times (the cross-sectional area of the irradiator decreased by 2.8 times) and, thus, the actual efficiency of the use of RLND radiation decreased despite a decrease in geometric radiation losses at the entrance and exit of the diffuser-reflecting irradiator zone inner surface. In addition, the power consumption for pumping air with the same capacity of 300 m ³ / h increased to ~ 65 watts. With a subsequent decrease in the internal diameter of the irradiator to 60 mm (d / D ≈ 4), the efficiency of the use of RLND radiation decreased by another 30%.

When the RLND axis was shifted by 25 mm from the axis of a cylindrical irradiator with a diameter of 90 mm, the average incident bactericidal intensity over the irradiator surface was 80 mW / cm ² , i.e., decreased by more than 15%. In addition, the heterogeneity of the distribution of light over the surface (and, consequently, the volume of the irradiator) increased. Similarly, the intensity of radiation incident on the inner surface of the irradiator decreased by 10-12% when the irradiator cross section was close to square with a side of 80 mm (the area of such a square is close to the area of a circle with a diameter of 90 mm).

When using rather short diffuser and confuser (in accordance with Fig. 2, the length of the confuser and diffuser in the flow is about 80 mm each) with a passage diameter of 100 mm from the same Teflon with a thickness of 3 mm, the incident intensity the light flux to the surface of the irradiator increased ~ 7.5 times compared with the case of an open lamp (up to ≈ 68 mW / cm ² ) plus the area of the diffusely reflecting inner surface of the irradiator increased by ~ 20% (its volume also increased), i.e. the gain in the bactericidal dose was about 25% compared with the cylindrical geometry; the power consumed by the lamp could potentially be reduced by the same amount (by ~ 35 W) at the same degree (dose) of sterilization. At the same time, the power consumption for pumping the air flow with an air flow of 300 m ³ / h amounted to about 11 W, increasing only by ~ 4 W.

2. In the irradiator in the form of a cylinder with an internal diameter of 152 mm, both the amalgam RLND and the XeBr * excimer lamp were located, with the RLND placed on the axis of the irradiator and the excimer lamp 45 mm from the axis of the irradiator.

The measurements showed that the inclusion of an excimer lamp with the RLND operating does not affect the intensity of the light incident on the surface of the irradiator with a wavelength of 254 nm (radiation from a mercury lamp). Similarly, the inclusion of RLND when the excimer lamp is operating does not affect the intensity of light incident on the surface of the irradiator with a wavelength of about 280 nm (excimer lamp radiation).

3. As indicated in example 1, already for a cylindrical case of an irradiator with a diameter of 152 mm with an RLND radiation power of 40 W and a productivity of 300 m ³ / h, the generated bactericidal dose is ~ 15 times higher than 99.9% sufficient for the degree of sterilization of Staphylococcus aureus, while power consumption for bactericidal radiation is about 140 watts, and for pumping air - 7 watts. A significant, for example, 5–10 times increase in the productivity of such an irradiator, based on the value of the bactericidal dose, would require a sharp increase in pumping costs (in the first approximation, proportional to ΔV ³ ), in addition, for rooms with a volume of ~ 200 (up to 500) m ³ such performance is simply not required.

Thus, for irradiators of the indicated capacity according to the claimed technical solution, the urgent task is to drastically reduce the radiation power of the amalgam RLND while maintaining and even increasing its efficiency. This problem can be solved in the embodiment of the amalgam RLND proposed by the authors with additional heating of the amalgam.

For the RLND described above, additional heating of the amalgam was used, located on the outer surface of the lamp "opposite" to the amalgam spot, a heat source with a power of about 0.3 watts. The lamp was sealed by a cylindrical quartz tube (bulb) with an inner diameter of 25 mm and an outer diameter of 28 mm, the gap between the lamp and the outer quartz bulb was filled with atmospheric pressure xenon or could be pumped out. At a discharge current of ~ 0.15 A, the lamp power consumption was ≈18 W, and the ultraviolet radiation power was 8 ÷ 8.5 W. Thus, the technical efficiency of the lamp was ~ 45%, which ensured a bactericidal dose of ~ 1300 J / m ³ and a very high degree of sterilization with a total power consumption of about 25 W instead of 150 W for the irradiator productivity of 300 m ³ / s ( with a degree of sterilization above 99.9% for Staphylococcus aureus) 1 cubic meter of air per hour is less than 0.1 W compared to ~ 1 W / (m ³ / h) for commercial indoor recirculators and ~ 0.5 W / (m ³ / hour) in the prototype.

Thus, the technical result provided by the combination of features provided in the claimed utility model is the optimization of closed bactericidal irradiators, namely, a significant increase in their effectiveness while reducing energy consumption, as well as reducing the cost of such irradiators. In addition, the use of amalgam mercury lamps with an additional source of amalgam heating in moderate irradiators provides an increase in the life of such lamps and, therefore, a significant increase in the life of a bactericidal irradiator as a whole.

A comparative analysis of the claimed utility model and known analogues reveals the presence of distinctive features in comparison with the closest analogue, which ensures that it meets the criterion of "novelty."

The ability to create the inventive bactericidal irradiator based on well-known components and technologies (for example, Teflon sheets or pipes of the required thickness and purity, technology for forming a diffusely reflecting coating with a reflection coefficient of 90 ÷ 95% in the bactericidal range of the spectrum, amalgam RLND and excimer lamps, etc.) , as well as the possibility of manufacturing the variant of the amalgam lamp described in the application with an additional amalgam heating source and a sealed heat-insulating cap transparent for radiation, providing so the claimed technical solution complies with the criterion of "industrial applicability", some specific embodiments thereof have been described above.

In order to meet any possible specific requirements, changes to the above described embodiments of the closed bactericidal irradiator as well as its alteration without deviating from the provisions protected by the claims can be made obvious to those skilled in the art. In particular, at the entrance to the irradiator case, pre-filter (s) and various turbulators and flow rotators (which can also be placed in the volume of the irradiator case) can be located, various control and monitoring systems for the parameters of the bactericidal irradiator and the environment (sterilized flow), additional filters can be applied at the output of the irradiator housing, as well as various options for eliminating the output of ultraviolet radiation outside the irradiator housing, etc. . Amalgam heating in a low-current RLND can be carried out by a discharge current due to an appropriate modification of the discharge circuit or an independent power source, in the latter case, the specified source may include a feedback element to maintain the amalgam's optimal temperature, the gas gap between the lamp and the transparent bulb tightly enclosing it can be filled with various gas composition or be evacuated (evacuated), etc., some possible modifications of the inventive bactericidal sterilizer were also indicated in the description.

Claims (13)

1. A bactericidal irradiator, including at least one low-pressure mercury lamp as a source of ultraviolet radiation of the bactericidal range for irradiating the sterilized air stream, the case of the irradiator with the inlet and outlet sections for the sterilized air stream, covering the region of the air stream irradiated with a source of ultraviolet radiation, the main part of the inner surface of which is made diffusely reflecting, at least one fan for pumping air flow through the irradiator, moreover, the body of the irradiator is made essentially axisymmetric in shape with a low-pressure mercury lamp located close to its axis and geometric parameters in accordance with the following conditions: s / (s + S) <0.1; d / D <0.2, where s is the internal surface area of the irradiator without a diffusely reflective coating, S is the internal surface area of the irradiator with a diffusely reflective coating, d is the diameter of the low-pressure mercury lamp, D is the characteristic internal transverse dimension (diameter) of the irradiator body . 2. The bactericidal irradiator according to claim 1, in which the housing has a substantially elongated cylindrical shape in which the ratio of the length of the housing to its transverse size (diameter) exceeds 3, preferably exceeds 5. 3. The bactericidal irradiator according to claim 1, wherein the cross-sectional area of the irradiator body at the inlet and / or outlet of the air flow from the irradiated area is less than the cross-sectional area of the main part of the irradiator body. 4. The bactericidal irradiator according to claim 1, wherein the irradiator housing is made up of at least two independently manufactured parts. 5. The bactericidal irradiator according to claim 1, in which at least a part of the surface of the fan facing the irradiated region of the air flow is diffusely reflecting bactericidal radiation of the ultraviolet range. 6. The bactericidal irradiator according to claim 1, wherein an air duct is additionally located at the inlet of the air flow to the irradiator and / or the outlet of the air flow from the irradiator, wherein the inner surface of the duct is made of a material that absorbs ultraviolet radiation of the bactericidal range. 7. The bactericidal irradiator according to claim 1, in which the low-pressure mercury lamp has at least one amalgam source of mercury atoms located on the inner surface of the lamp. 8. The bactericidal irradiator according to claim 7, in which the low-pressure mercury lamp has at least one additional heating source of at least one amalgam source located on the outer surface of the lamp in the area of the amalgam source, and further includes a bulb transparent to radiation mercury lamp material, covering the lamp, and in a preferred embodiment, the bulb is sealed. 9. The bactericidal irradiator according to claim 1, in which there is at least one additional source of bactericidal ultraviolet radiation, which is an excimer lamp.

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