RU2206831C2 - High-temperature installation for burning solid medical waste - Google Patents

Abstract

FIELD: incineration engineering. SUBSTANCE: high-temperature installation uses oxidized air as oxidant. Incinerator is essentially uniflow cylindrical combustion chamber with cooling jacket made of two folded metal sheets joined by spot welding at points of stamped depressions on external sheet for protecting incinerator against burnout at internal temperatures up to 2000 C. Mounted in head part of combustion chamber are screw-feed system for solid wastes with cutter at outlet, conical crushing shafts, and respective cooling jacket; spray nozzles for air oxidizing; incinerator burner incorporating oxidized air and municipal gas feed pipe with igniter- discharger. Intermediate part of incinerator accommodates screw device for feeding dust and ash to incinerator; mounted at incinerator outlet are cooling-air intake pipe, afterburner with oxidized air injectors and respective cooling jacket, fire-bars with slag accumulating bin, tap hole for collecting metal and glass, and steam-tube exhaust-heat boiler. Mounted at incinerator inlet are compressor with double- cartridge silica gel desiccator unit and one more compressor with double-cartridge short-cycle zeolite unit and heat exchanger communicating with incinerator cooling system incorporating provision for heating oxidized air to 500-600 C. Mounted at exhaust-heat boiler outlet are electrostatic dust precipitator, cyclone, wet scrubber with two exhaust fans, power unit having steam turbine and power generator capable of producing up to 150 kW at incinerator capacity of 100 kg/h. Circulating water supply system of installation has service water tank with pipe admitting clarified water from scrubber, turbine waste steam, service tank makeup by tap water, and warm water outlet, and cooling tower provided with pump for feeding circulating water to waste-heat boiler and to scrubber. EFFECT: enhanced efficiency and safety of waste incineration. 3 cl, 2 dwg

Description

 The invention relates to techniques for incineration, in particular for high-temperature incineration of solid medical waste.

 Medical (hospital) wastes pose a huge danger to the population and the environment, especially if these wastes come from infectious diseases hospitals.

 The greatest danger, especially for children, is disposable syringes and discarded tabletted expired medicines.

The world practice of liquidating such wastes indicates that they need to be burned in high-temperature (up to 2000 ^o С) installations (furnaces) directly on the territory of large hospital (especially infectious) institutions. This will completely eliminate the transfer of infectious materials outside the hospital. This practice has recently been applied in the USA, Japan, Sweden, Denmark and uses specialized installations for this purpose (plasma furnaces, plasma-chemical neutralization, electric arc furnaces, dry pyrolysis, etc.), allowing to increase the temperature to 3000 ^o С at a huge cost of electricity .

 Moscow also supports this concept. On September 28, 2000, the Moscow City Duma considered a similar proposal by the Committee on Environmental Policy and decided to "create 3 to 4 enterprises for centralized service of hospitals and 7 separate facilities located on the territory of infectious diseases hospitals (Pharmaceutical Bulletin, October 38, 17, 2000).

The objective of the present invention is to provide such an installation, which would allow to increase the temperature to 2000 ^o C.

 The problem can be solved by using up to 50-60% oxygenated air for burning waste.

The closest analogue is US patent 4848250, MKI F 23 F 5/06, publ. 07/18/89 (Wundertey John M.), where the waste is burned in five chambers at a temperature of 2200 ^o With the supply of gaseous oxygen.

 The disadvantage of this invention is the need to use gaseous bottled oxygen or to create a turbo-expander oxygen station to produce pure oxygen and low reliability of individual units.

 A new technical result in the present invention is obtained by using the process of air acidification by separating part of the nitrogen on the regenerated sorbent and using a once-through, cooled (type of rocket) combustion chamber — a furnace.

A high-temperature solid medical waste incinerator, using oxygenated air as an oxidizing agent, is a direct-flow cylindrical combustion chamber with a cooling jacket made of two rolled metal sheets by spot welding in places of stamped recesses on the outer sheet and able to protect the furnace from burnout at temperature inside up to 2000 ^o С, in the head of the combustion chamber there is a screw system for feeding solid waste with a cutter at the exit, a cone with shaped shredders-shredders and a cooling jacket, nozzles for oxygenated air and a burner for igniting the furnace, consisting of fittings for supplying oxygenated air and city gas with an igniter-discharger; in the middle of the furnace there is a screw device for feeding dust and ash into the furnace; at the outlet of the furnace there is an inlet fitting for cooling air, an afterburner with nozzles for oxygenated air and its own cooling jacket, grates with a hopper for collecting slag, and a tap hole for collecting molten metal and glass, and a steam tube waste heat boiler; at the entrance to the furnace there is a compressor with a two-cartridge block of desiccant with silica gel and another compressor with a two-cartridge block of short-cycle zeolites and a heat exchanger associated with the cooling system of the furnace, which can heat oxygenated air to a temperature of 500 - 600 ^o C; at the outlet of the recovery boiler there is an electric dust filter, a cyclone, a wet scrubber with two smoke exhausters, an energy unit consisting of a steam turbine and an electric generator, a water tank with fittings for entering clarified water from the scrubber, the exhaust steam of the turbine, and replenishment of the supply tank with tap water and the outlet of warm water to the cooling tower having a pump for supplying recycled water to the recovery boiler and scrubber.

 A schematic block diagram of the proposed high temperature solid medical waste incinerator is shown in FIG. 1.

 The basis of the entire installation is block Z (figure 2). It consists of a furnace (combustion chamber) 1 with a cooling jacket 2, tuyeres (nozzles) 3 for supplying oxygenated air, a screw 4 for supplying garbage to the furnace with a drive 5, a heating jacket 6, cone-shaped shredders 7 and a cross-shaped knife 8.

 At the outlet of the furnace there is an afterburner 9 with a cooling jacket 10, tuyeres 11 for oxygenated air C and a fitting for supplying cooling air E. After the afterburner, a waste heat boiler 13 with a fitting 14 for feeding water A and a fitting 15 for steam N.

 The recovery boiler 13 has a fitting 16 for exhaust gas G.

 In the lower part of the furnace 1 there is a grate 17 with a hopper 18 for collecting slag (ash) J and removing it on the conveyor 19, as well as a tap hole 20 and a trolley 21 for collecting molten metal and glass K.

 To ignite the furnace, a burner 22 is installed, which works when burning oxygenated air D and city gas (methane) L, ignited by an igniter-spark gap 23 or pyrozapal.

 In the upper part of the furnace there is also a distributor of oxygenated air 24 for flows C and D and a nozzle 25 for the exit of hot air F. In the middle part of the furnace there is a dust receiver 26 with an auger 27, and a drive 28, and an outlet pipe 29. The furnace cooling unit consists of a compressor 30 with a drive 31 and a fitting 32 (see Fig. 1) for entering cold air E.

 At the inlet to the furnace there is a compressor 33 with a drive 34, a two-cartridge air dryer unit with silica gel 35 and with fittings 36 for entering cold air, 37 - for entering hot air P and a fitting 38 for entering humidified air R. After compressor 33, a two-cartridge unit with short cycle zeolites 39 with a fitting 40 for the release of nitrogen S; a heat exchanger 41 is connected to block 39, connected by fittings to flows B, F, and P.

 The dust and gas cleaning unit (at the outlet of the waste heat boiler 13) consists of an electric dust filter 42, a cyclone 43 and a wet scrubber 44 with smoke exhausters 45 and 46 passing into the exhaust gas pipe G.

 The energy block located at the outlet of the waste heat boiler 13 consists of a steam turbine 47 and an electric generator 48.

 The reverse water supply consists of a supply tank 49 for water with fittings for entering clarified water T from the scrubber 44, spent steam N of the turbine 47, feeding the supply tank with tap water U and the outlet of warm water to the cooling tower 50, with pumps 51 for supplying water to the cooling tower and 52 - for supplying circulating water A to the waste heat boiler 13 and the scrubber 44.

 In the immediate vicinity of the installation there is a control panel 53.

 The cooling jacket of furnace 1 is made of two steel shells interconnected by spot welding, similar to rocket engines of OKB A.M. Isaev, through the "warts" 54 (see fragment X in Fig. 2).

 The installation operates as follows (see Fig. 1 and 2).

Medical waste (MO stream) is discharged into a roller grinder 7, they are sent after grinding into the screw 4, along the length of the screw, the waste is dried with hot air coming from the cooling jacket 2 of the furnace and the cooling jacket 6 of the screw. The waste is fed into the furnace 1, after being crushed on a cross-shaped cutter 8. The waste is ignited using a burner 23 operating on oxygenated air (stream D) and city gas (stream L) using a discharge, arc, or pyrozapal. Additionally, ash and dust (stream M) are supplied to the furnace through a pipe 29 using a screw 27 from an electric dust filter 42 and cyclone 43. The metal and glass melted at a temperature in the furnace up to 2000 ^° C are collected through a notch 20 into a trolley 21, and the ash is collected in the hopper 18, and then remove it for further use using the conveyor 19.

The waste products of combustion are burned in the afterburner 9, supplying oxygenated air through lances 11 (stream C), and then sent to a waste heat boiler 13, from where (stream G) they are sent to an electric dust filter 42, cyclone 43 and a wet scrubber 44, where gas cleaning is completed and direct stream C to the exhaust gas pipe. Oxygenated air is produced from the surrounding atmosphere, nitrogen (stream S) is separated from it using a two-cartridge block of short-cycle zeolites 39, bringing the oxygen concentration in the air to 40-60 vol. % At the same time, in order to increase the temperature in the furnace, oxygenated cold air is heated to a temperature of 500-600 ^° C by the stream F in the heat exchanger 41 and directed (stream B) to the furnace.

To ensure the normal operation of zeolites, the air is preliminarily dried in a two-cartridge silica gel desiccant block 35, the regeneration of which is carried out using hot (250 - 350) ^o C air (stream P) coming from the heat exchanger 41. Supply of outside air (stream E) to cool the afterburner , the inner surface of the furnace 1 and the screw 4 is carried out using a compressor 30.

 For the production of electricity using high steam recovery boiler 13, a steam turbine 47 and an electric generator 48.

 The spent steam of the steam turbine is transformed into water in the supply tank 49 and cooling tower 50, and the condensate (stream A) is sent to feed the waste heat boiler 13.

 For large waste incineration capacities, for example 6 tons per hour, the electric power can be 15,000 kW, with a capacity of 100 kg per hour - not more than 150 kW.

 Hence the conclusion: for small capacities (less than 100 - 150 kg / h of waste), the technological scheme should be simplified by excluding the waste heat boiler (pos. 13), the energy block (pos. 47, 48) and reverse water supply (pos. 49. 50.51, 52).

A new technical result when using the invention is also that it allows you to completely solve the problems existing in the technology of incineration:
- the problem of eliminating dioxins generated during the burning of garbage at temperatures up to 1400 ^o C;
- the problem of using ash as a fertilizer in connection with the removal of heavy metals and other harmful impurities from it;
- The problem of the complete and safe disposal of infected medical waste.

 FIG. 1 - Block diagram of a high temperature solid medical waste incinerator.

 FIG. 2 - Block Z for burning solid medical waste.

Claims (3)

1. A high-temperature installation for burning solid medical waste using oxygenated air as an oxidizing agent, characterized in that the furnace is a direct-flow cylindrical combustion chamber with a cooling jacket made of two rolled metal sheets by spot welding in places of stamped recesses on the outer sheet and having the ability to protect the furnace from burnout at a temperature inside of up to 2000 ^o C, a screw system for feeding solid waste is located in the head of the combustion chamber in with a cutter at the exit with cone-shaped shafts - shredders and a cooling jacket, nozzles for oxygenated air and a burner for igniting the furnace, consisting of fittings for supplying oxygenated air and city gas with an igniter-discharger, in the middle of the furnace there is a screw device for feeding dust to the furnace and ash, at the outlet of the furnace there is an inlet fitting for cooling air, an afterburner with nozzles for oxygenated air and its cooling jacket, grates with a hopper for collecting slag and let and for collecting molten metal and glass and a steam-tube recovery boiler, a compressor with a two-cartridge block of desiccant with silica gel and another compressor with a two-cartridge block of short-cycle zeolites and a heat exchanger connected with the furnace cooling system, which can heat oxygenated air to a temperature of 500 - 600 ^o C, at the outlet of the waste heat boiler arranged elektropylevoy filter, a cyclone, a wet scrubber with two exhaust fans, power unit consisting of a steam turbine and electric of a generator capable of generating solid waste up to 150 kW of electricity at a capacity of 100 kg / h, the plant’s recycling water supply consists of a water supply tank with fittings for entering clarified water from a scrubber, spent steam from a turbine, replenishing the supply tank with tap water and warm water outlet to a cooling tower having a pump for supplying circulating water to a recovery boiler and a scrubber.  2. The high-temperature installation for burning solid medical waste according to claim 1, characterized in that the ignition of the burner for ignition of the furnace can be pyrozapal. 3. The high-temperature installation for burning solid medical waste according to claim 1, characterized in that the oxygen concentration in the oxygenated air is 40-60%, and its temperature at the inlet of the furnace reaches 500-600 ^° C, the air temperature for silica gel regeneration is 250 - 350 ^o C.

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