FR2796134A1 - Fuel oil pre-combustion heating system has one or more housings with heating circuit between outer and inner components - Google Patents

Abstract

The system consists of one or more housings, each comprising outer (8a) and inner (7a) components which have a space (18) between them forming a heating circuit. At least one of the two components making up each housing is equipped with heaters (12), and the housings are connected in series by transfer pipes (10), while a pump with a return pipe extracts the fuel oil after it has been heated and returns any surplus. The components forming each housing are e.g. coaxial pipes, with the inner one closed at one end to augment its capacity. Temperature (16a) and safety (16b) sensors control the temperature to which the oil is heated.

Description

The present invention relates to a fuel preheating device comprising a heated circuit in which the fuel oil circulates before combustion including in a boiler.

The invention will particularly find its application in the field of the preheating of fuel oil before its use in boilers but may be applied differently, especially for preheating before use in drive members.

<I> In the </ I> framework of the <I> preheating </ I> of <I> fuel oil, the document FR-A-2 <I> 770 621 </ I> which <I> > presents a </ I> autonomous fuel <I> economizer, <I> pollutant gas </> reducer <I> to obtain <I> clean fuel </ I> I> of which <I> two </ I> elements <I> are </ I> <I> indispensable: </ I> the almost complete disappearance <I> of the viscosity </ I> allowing a <I> perfect mixture AIR I LIQUID </ I> and <I> its </ I> increase <I> volumic maximum. For </ I> perfect obtaining of <I> these two </ I> elements and thus <I> of </ I> the resultant Economy / Reduction <I> of pollution, </ I> it <I> is imperative that </ I> the exchanger (4) has only a <I> very thin oil passage, 2 </ I> mm <I> only, </ I> so <I> to get < / I> an immediate <I> heat exchange <I> <I> and to benefit </ I> in <I> permanence of the <I> return </ I> hot <I> surplus </ I> I> liquid <I> discharged by the </ I> pump <I> in </ I> the exchanger (4/1), the latter being <I> placed </ I> before <I> the pump </ I> and not <I> after. </ I> The apparatus presented in this document is already an important technical advance with respect to the preheating devices before taking into account that it realizes an efficient heating of the fuel oil by the through a transfer in a heated circuit of small section; however, this technique is not without drawbacks.

Thus, it provides for a preheating of the fuel oil by means of a coolant, in this case oil. This intermediate element increases the inertia of the system as well as the losses. Therefore, the heating time and energy consumption required for preheating can be significantly improved.

Moreover, the autonomous apparatus presented in document FR-A-2,770,621 has a limited capacity. Therefore, this device will not be suitable for heavy fuel consumption except to provide a very large device whose size will be particularly troublesome.

Another disadvantage is the complex design of this device. This design has a high cost which compromises the interest of such a device whose primary objective is to save in the consumption of fuel oil.

The object of the present invention is to propose a device for preheating fuel oil which overcomes the drawbacks of current devices.

Firstly, the invention allows a preheating of the fuel oil in order to feed the downstream element (for example a boiler) under optimum temperature conditions of the fuel oil. The viscosity and the intrinsic properties of the fuel are thus substantially improved.

An important object of the invention is to allow a reduction in the cost of preheating devices.

In addition, it offers a wide range of operation in capacity and flow for each device size. In this way, we limit the number of device formats necessary to adapt to the different needs of the market according to the annual consumption of the boilers and their nominal powers. The invention thus provides greater standardization for preheating devices.

Another advantage of the invention is its low energy consumption for heating oil. Indeed, it achieves a rapid intake of heat and maintenance at economic temperature. In addition, in a particular embodiment, a readmission of the surplus of uncooled hot oil is carried out, which contributes to maintaining the temperature.

Another object of the invention is to provide a variable capacity for the device by simply using a plug. The device presented here will also allow a complete regulation of the operation by means of measuring means and associated heating control.

The present invention relates to a fuel preheating device comprising a heated circuit in which the fuel oil circulates before combustion, in particular in a boiler,

according to the invention, it comprises at least one heating body formed of an outer member and an inner member fitted and extending longitudinally in the same direction so as to define, between the inner wall of the outer member and the outer wall of the inner member, a spacer space constituting the heated circuit. The device may be in the embodiments described below

- At least one of the two elements is provided with heating means.

it comprises at least two heating bodies connected in series by transfer ducts.

- It includes a pump for the evacuation of the oil after preheating.

- It includes a return circuit from the pump to one of the heating bodies, for the readmission of the surplus pumped fuel oil. the inner and outer elements are coaxial tubes. - the inner element is hollow and clogged with one of its

ends to increase the capacity of the heating body. a wire of diameter corresponding to the difference in radii of the elements is wound helically on the outer wall of the inner element to form a helical heated circuit.

it comprises one or more temperature sensors at each heating element, and one or more safety sensors at each heating element.

it comprises means for controlling the heating means according to the measured temperature in order to regulate the temperature in each heating element according to the desired set point.

The accompanying drawings are given as an indicative and nonlimiting example. They represent an embodiment according to the invention. They will make it easy to understand the invention.

FIG. 1 is a general view of the invention in a particular embodiment with three heating bodies

FIG. 2 is a more detailed view of a heating body. FIG. 3 illustrates a device according to the invention with

schematization of the passage of fuel oil between the different constituent elements

Referring to FIG. 1, a preheating device according to the invention is shown comprising three heating bodies 1, 2, 3. This device is positioned between a storage tank for the fuel oil and the boiler or any other element using the fuel oil. . The tank and the boiler are not shown. However, the intake channel 4 is illustrated from the tank to the device and the supply channel 6 at the outlet of the device to the boiler.

The preheating device comprises a heated circuit in which the fuel oil circulates. This circuit taken by the fuel oil is illustrated in Figures 1 to 3 by arrows. This circulation is presented from the intake lane 4 to the feed lane 6.

During its transfer illustrated by the arrows, the fuel oil is gradually heated.

According to the invention, the heated circuit is constituted by an interspace 18 identified in FIG. 2. This intermediate space 18 is of small thickness, for example 3 mm, in order to constitute a heated circuit of limited size at the level of which an effective heat input can be achieved without using very powerful heating means and without the risk of coking.

The supply of heat is achieved by one or the other of the walls 19, 20 limiting the interspace 18.

Of course, other heating means are feasible. As also illustrated in Figure 2, the spacer 18 is defined according to the invention by the cooperation of an outer member 8a, b, c and an inner member 7a, b, c. These two elements 8a, b, c and 7a, b, c are made and assembled in such a way that they extend longitudinally in the same direction so as to define when they fit the interspace 18.

According to the embodiment illustrated in Figures 1 to 3, the inner and outer elements are coaxial tubes. The common axis of these tubes is identified at the mark 21 in FIG.

Different materials and different dimensions are possible for the tubes constituting the inner element 7a, b, c and the outer element 8a, b, c. it is thus possible to use metal tubes with an outside diameter of 44 mm for the inner element 7a, b, c and with an inside diameter of 50 mm for the outer element 8a, b, c.

As illustrated in the figures, the inner elements 7 a, b, c and outer 8 a, b, c are preferably nested centrally. In this way, the interspace 18 is regular over the entire periphery of the elements. In a particular embodiment, the element

inside 7 a, b, c is hollow and plugged at one of its ends to increase the capacity of the heating body 1, 2, 3. A plug 9 performing this function is illustrated in Figure 2. In this way, it is possible to increasing the capacity of each heating element 1, 2, 3 by filling the interior of the inner element 7a, b, c hollow.

At each heating element 1, 2, 3 are present heating means 12 for preheating the fuel oil.

Different embodiments are possible for the heating means 12. However, it will be possible to use heating electric resistances for example of collar type suitable for surrounding the outer element 8a, b, c. The electric heating resistance may also be positioned at the inner element 7a, b, c.

In a preferred embodiment, use is made of 3 heating bodies 1, 2, 3 as illustrated in FIGS. 1 and 3. The flow of fuel oil between each heating element 1, 2, 3 is effected by way of transfer ducts 10 also illustrated in Figures 1 and 3.

The use of several heating bodies 1, 2, 3 positioned in series allows the progressive heating of the fuel oil from the first heating body 1 to the last 3 before the supply of the boiler. By way of example, it will be possible to reach a maximum temperature at the output of the device of the order 85 C.

To allow the circulation of fuel oil and the supply of the boiler a pump 5 is positioned at the outlet of the last heater 3. A pump 5 of current design can be used.

In practice, the pump will be constituted by the burner pump. No additional costs will be incurred at this level. In a particular embodiment, a return circuit 11 is formed from the pump 5 to one of the heating bodies 1, 2, 3. In this way, after pumping through the pump 5, a return of the surplus of hot oil to the device is made.

As shown in FIG. 3, each heating element 1, 2, 3 may be presented intermediately between the outer element 8 a, b, c and inside 7 a, b, c a wire 15 of diameter corresponding to the difference of the radii elements 8a, b, c; 7 a, b, c. As shown, the wire 15, for example copper, is wound helically on the outer wall 20 of the inner member 7a, b, c. In this way, the heated circuit is constituted helically and allows a slower circulation and a more progressive heating of the fuel oil during its transfer into the heating body 1, 2, 3.

With reference to FIG. 2, it can be seen that the heating element 1, 2, 3 can comprise a reservation 17 in which temperature sensors 16 a can be inserted as well as safety sensors 16 b. In this way, it is possible to know the temperature of each heating body 1, 2, 3 and to ensure the safety of each element of the heating body in case of overheating.

The knowledge of the temperature in the device can be exploited to regulate the operation. Indeed, the invention may also comprise control means

heating means 12, according to the temperature measured in order to regulate it in each of the heating bodies 1, 2, 3. In this way, the operation of the heating means 12 is limited to the only periods necessary to obtain the desired temperature setpoint. In addition, this gives a temperature output of the device perfectly adjusted.

the operation of the device in the embodiment illustrated in the figures and particularly in FIG. 3 is described below. After the pump 5 is started up, the fuel oil is admitted into the device via the intake port 4. The first heating body is then gradually filled.

By means of the transfer conduits 10, the fuel oil reaches the following heating bodies 2, 3. During this transfer, the fuel oil passes through the intermediate space 18 defined between the outer elements 8a, b, c and inner 7a, b, c. Heating of the fuel oil is carried out at this level by means of the heating means in the form, for example, of electric heating resistances sheathing the outer element 8 a, b, c.

At the outlet of the last heating body 3, the fuel oil is pumped and can be used by the boiler via the feed path 6. The surplus pumped hot oil can be fed back into one of the heating bodies 2 by through the return circuit there.

In the case where the outer elements 8a, b, c and inner 7a, b, c are constituted by metal tubes, their assemblies are carried out in a simple manner and their ends can be plugged by inserts as presented by the FIGS. REFERENCES 1. ter heating body

2. 2nd heating element 3. 3rd heating element 4. Intake channel

5. Pump

6. Feeding path

7. (a, b, c) inner element 8. (a, b, c) outer element 9. Stopper

10. Transfer duct 11. Return circuit 12. Heating means 13. Base

14. Lid 15. Thread

16. has temperature sensors 16. b safety sensors 17. Reservation

18. Interspace 19. Inner wall

20. Outer wall 21. Longitudinal axis

Claims (10)

1. A device for preheating the fuel oil comprising a heated circuit in which the fuel oil circulates before combustion, in particular in a boiler, characterized in that it comprises at least one heating element (1, 2, 3) formed of an element outside (8a, b, c) and an inner member (7a, b, c) nested and extending longitudinally in the same direction to define between the inner wall (19) of the outer member (8a, b, c) and the outer wall (20) of the inner member (7a, b, c), a spacer (18) constituting the heated circuit. 2. Device according to claim 1, characterized in that at least one of the two elements (7a, b, c; 8a, b, c) is provided with heating means (12). 3. Device according to any one of claims 1 or 2, characterized in that it comprises at least two heating bodies (1, 2, 3) connected in series by transfer ducts (10). 4. Device according to any one of claims 1 to 3, characterized in that it comprises a pump (5) for the discharge of the oil after preheating. 5. Device according to claim 4, characterized in that it comprises a return circuit (11) from the pump (5) to one of the heating bodies (1, 2, 3), for the readmission of the surplus pumped hot oil. 6. Device according to any one of claims 1 to 5, characterized in that the inner elements (7a, b, c) and outer (8a, b, c) are coaxial tubes. 7. Device according to any one of claims 1 to 6, characterized in that the inner member (7a, b, c) is hollow and plugged at one of its ends to increase the capacity of the heating body (1, 2, 3). 8. Device according to claim 6, characterized in that a wire (15) of diameter corresponding to the difference in radii of the elements (7a, b, c; 8a, b, c) is wound helically on the wall outer member (20) of the inner member (7a, b, c) to form a helical heated circuit. 9. Device according to any one of claims 1 to 8, characterized in that it comprises one or more temperature sensors (16 a) at each heating body (1, 2, 3) and one or more safety sensors (16b) or level of each heating element (1, 2, 3). 10. Device according to claim 9, characterized in that it comprises means for controlling the heating means (12) according to the measured temperature to regulate the temperature in each heating body (1, 2, 3) according to the instruction desired.