CN1288385C - Medical refuse burning system combining rotary furnace with circulating fluidized bed - Google Patents

Abstract

The invention discloses a medical waste incineration system combined with a rotary kiln and a circulating fluidized bed. In the incineration chamber composed of the rotary kiln and the circulating fluidized bed, the rotary kiln plays the role of pyrolysis and gasification, and the circulating fluidized bed plays the role of burning. In the circulating fluidized bed, the residence time of the pyrolysis flue gas of the rotary kiln is 3-4 seconds, the residence time of solid combustibles is 40-60 minutes, and the combustion efficiency is high, which ensures the efficient burnout of medical waste. Add limestone in the circulating fluidized bed to suppress the emission of acid gases such as hydrogen chloride, prevent the corrosion of the incinerator and the tail flue, and have a long service life of the incineration system; use a high-temperature air preheater to heat the combustion air to above 500 °C In normal operation, there is no need to inject oil to support combustion, which reduces operating costs; the flue gas quenching device cools the flue gas temperature from 550°C to 170°C within 0.5 seconds without contact between the flue gas and water, reducing the amount of dioxin Low temperature regeneration to prevent secondary pollution.

Description

Medical waste incineration system combined with rotary kiln and circulating fluidized bed

technical field

The invention relates to a medical waste incineration system combined with a rotary kiln and a circulating fluidized bed.

Background technique

Medical waste refers to directly or indirectly infectious, toxic and other hazardous waste produced by medical and health institutions in the course of medical treatment, prevention, health care and other related activities. Medical waste pollutes the environment, spreads diseases, and threatens health. It is very harmful. It is the primary waste among the 47 types of hazardous waste in the "National Hazardous Waste List". In 2002, the country produced about 650,000 tons of medical waste, with an average daily output of 1,780 tons; it is estimated that by 2010, the national medical waste production will reach more than 680,000 tons, with an average daily output of 1,870 tons. In order to prevent social hazards and disease transmission caused by medical waste, protect the environment and safeguard human health, the construction of a centralized medical waste disposal project for whole-process management is an effective way to achieve safe storage and disposal of medical waste and protect people's health and environmental safety. In the construction of centralized disposal facilities, an incineration system with clean combustion and environmentally friendly emissions is particularly important. It is imminent to develop an incineration system with high combustion efficiency and pollutants that can strictly meet the emission requirements of the "Pollution Control Standards for Hazardous Waste Incineration" (GB18484).

Rotary kiln is a common medical waste incineration device at present, which is derived from the rotary calciner of cement industry. The rotary kiln is a cylindrical cylinder lined with refractory material, installed slightly inclined, the feed end is higher than the discharge section, the motor drives the cylinder to rotate around the axis through the transmission mechanism, and the medical waste is mixed, pyrolyzed and gasified , on fire, the garbage decomposes and gasifies into combustible gas during the slow rotation process. Therefore, it is often used as the primary combustion chamber of medical waste, and is equipped with a secondary combustion chamber for combustion. However, in the current actual operation, it is exposed at the outlet end of the rotary kiln that a large amount of solid pyrolysis products are discharged without being burned, and the function of the traditional secondary combustion chamber is used to burn out the gas. For the pyrolysis of the rotary kiln The remaining coke or solid residue has no further burnout function. On the one hand, it is difficult to achieve the goal that the rate of loss on ignition after pyrolysis is less than 5%, and on the other hand, it is easy to cause secondary pollution.

In addition, in the medical waste incineration system composed of rotary kiln and traditional secondary combustion chamber, due to the large amount of chlorine-containing disinfectants and plastic packaging bags contained in medical waste, the HCl content in the flue gas generated by medical waste incineration is as high as 1000ppm, causing The corrosion problem of the tail flue, especially the waste heat utilization system, is solved. In the most serious case, corrosion damage occurs in the tail flue after two to three months, which affects the normal operation of the system.

Circulating fluidized bed is a low-pollution and high-efficiency incineration technology that has been unanimously recognized in the electric power and environmental protection industries in recent years. 99%, suitable for high-efficiency and low-pollution combustion of various fuels such as coal, municipal solid waste, and sludge. Therefore, introducing circulating fluidized bed technology into medical waste incineration treatment, organically combining the advantages of rotary kiln and circulating fluidized bed, forming an efficient and clean incineration medical waste treatment system has broad application prospects.

Contents of the invention

The object of the present invention is to provide a medical waste incineration system in combination with a rotary kiln and a circulating fluidized bed.

A medical waste incineration system composed of a rotary kiln and a circulating fluidized bed. In the incineration system, the upper hopper is connected in turn with a feeder, a rotary kiln, a pyrolysis gas interface between the rotary kiln and a circulating fluidized bed, a circulating fluidized bed body, Circulating fluidized bed cyclone separator, circulating fluidized bed fluidized air preheater, flue gas quenching device, semi-dry flue gas purification device, bag filter, induced draft fan, chimney, circulating fluidized bed body is equipped with circulating flow Dilute-phase area of fluidized bed, dense-phase area of circulating fluidized bed, slag outlet, pyrolysis air and ember air air preheater and circulating fluidized bed fluidized air preheater connected in parallel, rotary kiln pyrolysis at the front end of rotary kiln The air pipe is connected to the upper end of the pyrolysis air and ember air air preheater, and the rear end of the rotary kiln is connected to the solid interface of the circulating fluidized bed through the rotary kiln and the dense phase area of the circulating fluidized bed body of the circulating fluidized bed. The lower end of the bed cyclone separator is connected to the circulating fluidized bed dense phase area of the circulating fluidized bed body through the circulating fluidized bed return device, and the lower end of the circulating fluidized bed body is fluidized with the circulating fluidized bed through the circulating fluidized bed fluidization air pipe The upper ends of the wind preheaters are connected. The lower end of the circulating fluidized bed fluidized air preheater is connected to the fluidization fan, and the pyrolysis air and ember air air preheater is connected to the pyrolysis air and ember air fans.

The present invention does not need oil to support combustion during normal operation, reducing operating costs; adding limestone as the bed material of the circulating fluidized bed can effectively inhibit the discharge of acid gases such as hydrogen chloride in waste incineration, and has a long service life; the circulating fluidized bed is composed of The second combustion chamber is incinerated at a medium temperature of 850-950°C. The solid materials and gas pyrolysis products have a long residence time in the circulating fluidized bed, and the combustion efficiency is high, which ensures the efficient burnout of medical waste and prevents secondary waste. pollute.

Description of drawings

The attached picture is a schematic structural diagram of a medical waste incineration system combined with a rotary kiln and a circulating fluidized bed. In the figure: 1. Hopper, 2. Feeder, 3. Bed pyrolysis gas interface, 6 rotary kiln and circulating fluidized bed solid interface, 7 circulating fluidized bed combustion air duct, 8 circulating fluidized bed body, 9 circulating fluidized bed cyclone separator, 10 limestone feeding device, 11 Circulating fluidized bed fluidized air preheater, 12 Circulating fluidized bed fluidized air pipe, 13 Pyrolysis air and ember air air preheater, 14 Circulating fluidized bed return device, 15 Pyrolysis air and ember air Fan, 16 fluidized air fan, 17 cooling water pump, 18 flue gas quenching device, 19 cooling tower, 20 semi-dry flue gas purification device, 21 bag filter, 22 induced draft fan, 23 chimney, 24 circulating fluidized bed dilute phase area, 25 circulating fluidized bed dense phase area, 26 slag outlet.

Detailed ways

The medical waste incineration chamber composed of the rotary kiln and the circulating fluidized bed of the present invention, the rotary kiln plays the role of pyrolysis and gasification of the waste, after the waste is fed into the rotary kiln, it slowly rotates forward in the rotary kiln, at 500-600°C The garbage is pyrolyzed under the action of hot air, and the combustible gas produced after pyrolysis is sent to the upper dilute phase zone of the circulating fluidized bed for combustion, and the remaining solid matter is sent to the lower dense phase zone of the circulating fluidized bed for combustion. The medical waste is tumbling in the rotary kiln, and the material is alternately exposed to the hot flue gas, while the temperature of the rotary kiln is relatively low, the material is heated evenly and slowly, and the moisture and volatilization are relatively uniform, which prevents the use of circulating fluidization alone. The problem of deflagration of flammable materials such as plastics when incinerating medical waste.

In the incineration system, the circulating fluidized bed plays a role in the burnout of the gaseous and solid phase products after pyrolysis. The overall temperature of the circulating fluidized bed is between 850 and 1050 ° C. The air is supplied by stages and the oxygen-enriched combustion has a strong reaction. After the solid material enters the circulating fluidized bed, it runs in a fluidized state, and its residence time exceeds 40-60 minutes, which ensures the burning of the solid material, and the thermal ignition loss rate of the discharged ash is less than 2%, which is far lower than the incineration standard .

After the combustible gas pyrolyzed by the rotary kiln enters the circulating fluidized bed, the gas contacts the high-concentration and high-temperature circulating solid particles of the circulating fluidized bed at 850-1050 °C, and the gas-solid two-phase undergoes intense heat exchange, so that the hot flue gas The temperature rises rapidly to above 800°C, and at the same time, it burns rapidly under the condition of high oxygen content fed by graded air supply. The flue gas stays in the circulating fluidized bed for more than 3 to 4 seconds, which can fully burn the combustible gas and effectively Suppresses the formation of harmful substances such as dioxin.

Limestone is added to the circulating fluidized bed as the bed material. Calcium oxide produced by pyrolysis of limestone under high temperature conditions can neutralize and react with acid gases such as hydrogen chloride produced in the incineration of medical waste, reducing the concentration of hydrogen chloride emissions and avoiding the tail equipment. corrosion problem.

The high-temperature flue gas from the circulating fluidized bed is first cooled to 500°C by the air preheater, and the pyrolysis air, fluidization air and ember air required for combustion are heated to above 500°C, and the high-temperature combustion-supporting air has increased The combustion temperature level in the incineration chamber enables medical waste to maintain combustion without auxiliary fuel.

The flue gas from the high-temperature air preheater is cooled to 170°C by the flue gas quenching device. The flue gas is quenched by water pipe heat exchange cooling method, the flue gas flows outside the pipe, and the water flows in the pipe without direct contact, avoiding the generation of sewage And the problem of secondary treatment, the residence time of the flue gas in the quenching device is less than 0.5 seconds, which reduces the low-temperature regeneration of dioxins in the flue gas.

As shown in the attached figure, the incineration chamber is composed of a rotary kiln and a circulating fluidized bed. The upper hopper 1 is connected with a feeder 2, a rotary kiln 4, a pyrolysis gas interface 5 between the rotary kiln and a circulating fluidized bed, and a circulating fluidized bed. Bed body 8, circulating fluidized bed cyclone separator 9, circulating fluidized bed fluidized air preheater 11, flue gas quenching device 18, semi-dry flue gas purification device 20, bag filter 21, induced draft fan 22, chimney 23. The circulating fluidized bed body 8 is provided with a circulating fluidized bed dilute phase area 24, a circulating fluidized bed dense phase area 25, and a slag discharge port 26. The pyrolysis air and ember air air preheater 13 and the circulating fluidized bed flow The chemical air preheater 11 is connected in parallel, the rotary kiln pyrolysis air pipe 3 at the front end of the rotary kiln is connected to the upper end of the pyrolysis air and ember air air preheater 13, and the rear end of the rotary kiln is connected to the solid interface of the circulating fluidized bed through the rotary kiln 6 is connected to the dense phase area of the circulating fluidized bed body 8, and the lower end of the circulating fluidized bed cyclone separator 9 is connected to the dense phase area of the circulating fluidized bed body 8 through the circulating fluidized bed return device 14 Then, the lower end of the circulating fluidized bed body 8 is connected to the upper end of the circulating fluidized bed fluidizing air preheater 11 through the circulating fluidized bed fluidizing air pipe 12 . The lower end of the circulating fluidized bed fluidized air preheater 11 is connected to the fluidization fan 16 , and the pyrolysis air and ember air air preheater 13 is connected to the pyrolysis air and ember air fan 15 .

In the incineration chamber formed by the combination of the rotary kiln and the circulating fluidized bed, the rotary kiln plays the role of pyrolysis and gasification of garbage, and the circulating fluidized bed plays the role of burning embers. The temperature of the rotary kiln is 400-600 ° C, while the circulating fluidized The temperature of the bed is 850-1050°C, the residence time of flue gas pyrolyzed in the rotary kiln in the circulating fluidized bed is 3-4 seconds, and the residence time of solid combustibles is 40-60 minutes. In the flue gas quenching device 18, the flue gas is outside the pipe, while the cooling water flows in the pipe.

The garbage is connected to the rotary kiln 4 by the garbage feeder 2, and is pyrolyzed and burned under the action of hot air from the pyrolysis air pipe 3 exceeding 500°C, and the combustible gas released from the combustion passes through the rotary kiln and the circulating fluidized bed pyrolysis gas The interface 5 is sent into the body of the circulating fluidized bed 8, and the dilute phase zone 24 of the circulating fluidized bed and the cyclone separator 9 constitute the second combustion chamber or burner chamber of the pyrolysis gas. In order to ensure sufficient oxygen supply; the solid matter remaining from the pyrolysis of the rotary kiln 4 is sent to the body of the circulating fluidized bed 8 through the solid interface 6 between the rotary kiln and the circulating fluidized bed, and these solid matters are fluidized in the circulating fluidized bed Under the fluidization action of wind 12, the incineration space composed of circulating fluidized bed dense-phase zone 25, dilute-phase zone 24, cyclone separator 9 and return device 14 is cyclically burned, and the residence time of solid materials in a high-temperature environment of 850-950°C is More than 30 minutes ensure that the solid materials are fully burnt out, the thermal ignition loss rate of the ash discharged from the furnace through the large slag port 26 is less than 2%, and the discharged ash can be directly used as building materials after metal removal.

The temperature range of the dilute-phase zone 24 of the circulating fluidized bed is maintained at 850-1050° C., and the residence time of the pyrolysis gas from the rotary kiln 4 in the dilute-phase zone 24 exceeds 2 seconds, and the residence time in the cyclone separator 9 exceeds 3 seconds. The complete combustion of gaseous products is ensured, the emission of organic pollutants such as dioxin is far below the environmental protection standard, and the reaction conditions of 850-1050°C make the emission of NOx lower than 50ppm.

The flue gas after combustion is cooled to 550°C by the circulating fluidized bed fluidized air preheater 11 and the pyrolysis air and ember air air preheater 13, while the corresponding combustion-supporting pyrolysis air and fluidization air are heated to 500°C ℃, which not only reduces the flue gas temperature, but also increases the combustion temperature. Under normal operating conditions, it is not necessary to add oil to support combustion, which reduces operating costs.

The flue gas is cooled from 550° C. to 170° C. within 0.5 seconds through the quenching device 18 to prevent low-temperature regeneration of dioxins. Then pass through the semi-dry flue gas purification device 20, the bag filter 21, and the induced draft fan 22 to discharge the chimney 23.

Different from the general incineration system of rotary kiln and second combustion chamber, the present invention provides the structure of incineration chamber combined with rotary kiln and circulating fluidized bed, so that solid materials and pyrolysis gas can be burned at a temperature of 850-1050°C. Burn completely. Limestone (CaCO ₃ ) is added to the circulating fluidized bed as the bed material. Under high temperature conditions, CaCO ₃ decomposes into CaO, which neutralizes the hypochlorous acid used for disinfection in medical waste and the hydrogen chloride produced in the incineration process of medical waste. It solves the corrosion problem of the equipment, prolongs the service life of the equipment, reduces the concentration of hydrogen chloride in the flue gas, and ensures that the discharge of hydrogen chloride meets the standards. Medical waste incineration causes secondary pollution.

Claims (3)

1, the medical refuse burning system of a kind of rotary kiln and recirculating fluidized bed coupling, it is characterized in that, rotary kiln and recirculating fluidized bed are united the Burning Room of formation, elevating hopper (1) is connected with batcher (2) in turn, rotary kiln (4), rotary kiln and recirculating fluidized bed pyrolysis gas interface (5), recirculating fluidized bed body (8), recirculating fluidized bed whirlwind separator (9), recirculating fluidized bed fluidized wind preheater (11), flue gas quenching apparatus (18), semi-dry fume purifier (20), sack cleaner (21), air-introduced machine (22), chimney (23), recirculating fluidized bed body (8) is provided with recirculating fluidized bed dilute-phase zone (24), recirculating fluidized bed emulsion zone (25), slag-drip opening (26), pyrolysis wind and burnt wind air preheater (13) and recirculating fluidized bed fluidized wind preheater (11) also connect, the rotary kiln pyrogenation airduct (3) of rotary kiln front end joins with pyrolysis wind and burnt wind air preheater (13) upper end, the rotary kiln rear end joins through the recirculating fluidized bed emulsion zone (25) of rotary kiln and recirculating fluidized bed solid interface (6) and recirculating fluidized bed body (8), recirculating fluidized bed whirlwind separator (9) lower end joins through the recirculating fluidized bed emulsion zone of recirculating fluidized bed loop back device (14) with recirculating fluidized bed body (8), recirculating fluidized bed body (8) lower end joins through recirculating fluidized bed fluidisation airduct (12) and recirculating fluidized bed fluidized wind preheater (11) upper end, recirculating fluidized bed fluidized wind preheater (11) lower end and fluidisation blower fan (16) join, and pyrolysis wind and burnt wind air preheater (13) join with pyrolysis wind and burnt wind blower fan (15).

2, the medical refuse burning system of a kind of rotary kiln according to claim 1 and recirculating fluidized bed coupling, it is characterized in that described rotary kiln and recirculating fluidized bed unite in the Burning Room of formation, the temperature of rotary kiln is 400～600 ℃, the temperature of recirculating fluidized bed is 850～1050 ℃, the time of staying of flue gas behind the rotary kiln pyrogenation in recirculating fluidized bed is 3-4 second, and solid combustible is 40～60 minutes in the time of staying of recirculating fluidized bed.

3, the medical refuse burning system of a kind of rotary kiln according to claim 1 and recirculating fluidized bed coupling, it is characterized in that in the described flue gas quenching apparatus (18), flue gas is outside pipe, and cooling water is in pipe, and the time of staying of flue gas in quenching apparatus was less than 0.5 second.

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