CN112303631A

CN112303631A - System and method for cooperation of pyrolysis and gasification of household garbage and chemical chain combustion

Info

Publication number: CN112303631A
Application number: CN202011326042.6A
Authority: CN
Inventors: 张向宇; 陆续; 张波; 向小凤; 徐宏杰
Original assignee: Xian Thermal Power Research Institute Co Ltd
Current assignee: Xian Thermal Power Research Institute Co Ltd
Priority date: 2020-11-23
Filing date: 2020-11-23
Publication date: 2021-02-02

Abstract

The present invention is a system and method for cooperating chemical chain combustion of domestic waste pyrolysis and gasification. and the first separator, the second separator and the third separator on the air reactor; the gasification reactor is used for pyrolysis of domestic waste; the side wall of the fuel reactor is provided with a limestone inlet; the air reactor is provided with several oxygen carriers; The inlet of the first separator is communicated with the pyrolysis gas outlet of the gasification reactor, the gas outlet of the first separator is communicated with the gas inlet of the fuel reactor; the inlet of the second separator is communicated with the outlet of the fuel reactor, and the tail gas outlet of the second separator is discharged into Atmosphere, the solid outlet of the second separator is communicated with the inlet of the air reactor; the second separator is provided with an SNCR spray gun; the nitrogen outlet of the third separator is discharged into the atmosphere, the inlet of the third separator is communicated with the outlet of the air reactor, and the third separator The solids outlet communicates with the fuel reactor oxygen carrier inlet.

Description

System and method for cooperation of pyrolysis and gasification of household garbage and chemical chain combustion

Technical Field

The invention relates to a household garbage treatment technology, in particular to a system and a method for household garbage pyrolysis gasification and chemical chain combustion.

Background

The waste incineration is the most widely adopted thermal treatment means at present, can lead toxic organic matters and pathogenic microorganisms in the waste to lose toxicity through pyrolysis, has the advantages of volume reduction, high weight reduction rate, quick treatment method and the like, and realizes the energy utilization of the waste by recovering heat generated in the incineration process; but SO contained in incineration flue gas_x、NO_xHarmful substances such as dioxin, heavy metal particles and the like can cause pollution to the environment; the existing garbage incineration equipment has large investment, high incineration waste gas treatment cost and great difficulty, and is generally used for centralized disposal of large-scale household garbage.

The pyrolysis gasification technology is a new garbage heat treatment technology, which is to convert organic matters in garbage into H-containing substances through a series of thermochemical reactions under certain temperature and pressure and in an oxygen-free or oxygen-deficient environment₂、CH₄、CO、C_nH_mAnd the like, combustible gas, tar and ash. The pyrolysis gasification technology is an efficient and clean urban garbage treatment method which is technically and economically feasible and can realize self-sustaining energy to a certain extent. Compared with incineration, the combustible gas generated after pyrolysis gasification can be used for power generation or energy supply, the energy utilization efficiency is higher, and meanwhile, no fuel or SO is required to be added₂And NO_xAnd the discharge amount of harmful gases is less, most heavy metals are fixed in ash, the leaching toxicity is low, and the treatment cost is relatively low.

Because the municipal solid waste has high volatile components, a certain amount of pollutants such as tar, N/S/Cl and the like can be generated in the pyrolysis gasification process, and certain environmental risks are brought. Therefore, the control of pollutants in the process of pyrolysis and gasification of the household garbage is a key premise for realizing the clean treatment of the household garbage. Chemical Looping Combustion (CLC) is a novel combustion technology that uses lattice oxygen in a solid oxygen carrier to completely oxidize fuel into CO in a fuel reactor by Looping reaction₂And H₂And O, re-oxidizing the oxygen carrier after reaction by air in an air reactor to recover the process of recycling the lattice oxygen. Chemical looping combustion technology has attracted much attention at home and abroad in recent years, for example, a chemical looping combustion power generation process and system using landfill gas disclosed in patent CN200910083719.5 includes a landfill gas collection system, a chemical looping combustion system and a fuel gas and steam combined cycle power generation system. For another example, CN201510256727.0 discloses a method for treating solid waste with low carbon and inhibiting the generation of dioxin, in which the crushed solid waste is subjected to chemical looping combustion, and the chemical looping combustion employs an oxygen carrier modified by an adsorbent, and is capable of adsorbing and fixing gaseous chlorine elements, and condensing and capturing carbon dioxide obtained by chemical looping combustion. For example, CN201510621464.9 discloses a method for fixing volatile heavy metals of chromium, cadmium, and lead, which utilizes chemical looping combustion to solve the problem of releasing chlorides of volatile heavy metals of chromium, cadmium, and lead in the current solid waste energy utilization process. However, the direct chemical looping combustion of solid waste belongs to solid-solid reaction, the reaction rate is slow, the reaction is incomplete, the material consumption is large, and the cost of waste treatment is increased.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a system and a method for pyrolysis and gasification synergistic chemical chain combustion of household garbage, which have simple structure, can realize clean, efficient and low-cost treatment of the household garbage, can flexibly adjust the scale, and are suitable for treating the small and medium-sized household garbage in small cities, counties or villages and towns.

The invention is realized by the following technical scheme:

a system for cooperation of pyrolysis and gasification of household garbage and chemical chain combustion comprises a gasification reactor, a fuel reactor and an air reactor which are sequentially connected, and a first separator, a second separator and a third separator which are respectively arranged on the gasification reactor, the fuel reactor and the air reactor;

the gasification reactor is used for pyrolyzing the household garbage; the side wall of the fuel reactor is provided with a limestone inlet; a plurality of oxygen carriers are arranged in the air reactor;

the inlet of the first separator is communicated with the pyrolysis gas outlet of the gasification reactor, and the gas outlet of the first separator is communicated with the gas inlet of the fuel reactor;

the inlet of the second separator is communicated with the outlet of the fuel reactor, the tail gas outlet of the second separator is discharged into the atmosphere, and the solid outlet of the second separator is communicated with the inlet of the air reactor; an SNCR spray gun is arranged on the second separator;

and a nitrogen outlet of the third separator is discharged into the atmosphere, an inlet of the third separator is communicated with an outlet of the air reactor, and a solid outlet of the third separator is communicated with an oxygen carrier inlet of the fuel reactor.

Further, the limestone inlet is arranged on the side wall below the outlet of the fuel reactor.

Furthermore, the SNCR spray gun is arranged on the side wall opposite to the inlet of the second separator, and the spray direction is vertical to the side wall.

Furthermore, the bottom of the gasification reactor is provided with a gasification agent inlet, and the side wall of the gasification reactor is provided with a material inlet and an ash inlet.

Furthermore, a material inlet of the gasification reactor is sequentially connected with a storage bin and a screw feeder.

Furthermore, the ash inlet of the gasification reactor is connected with the ash outlet at the bottom of the first separator.

Further, the bottom of the air reactor is provided with an air inlet.

A method for generating electricity by coupling domestic garbage incineration with coal burning comprises the following steps,

step 1, feeding the household garbage into a gasification reactor, carrying out gasification reaction with a gasification agent to generate a mixture of pyrolysis gas and ash, carrying out gas-solid separation in a first separator, and introducing the pyrolysis gas obtained by separation into a fuel reactor;

step 2, in the fuel reactor, an oxygen carrier and pyrolysis gas are subjected to reduction reaction, and a reaction product enters a second separator; in the second separator, the reduced oxygen carrier and the flue gas are subjected to gas-solid separation; under the combined action of limestone and an SNCR spray gun, the flue gas is discharged into the atmosphere through a tail gas outlet after dioxin, oxysulfide and nitric oxide are removed; the reduced oxygen carrier enters an air reactor;

step 3, the reduced oxygen carrier in the air reactor and oxygen in the air are subjected to oxidation reaction and then enter a third separator; in the third separator, the oxygen carrier and nitrogen gas are subjected to gas-solid separation, the nitrogen gas is discharged through a nitrogen gas outlet, the oxygen carrier enters the fuel reactor through an oxygen carrier inlet, and the steps are repeated and circulated.

Further, in the step 1, the gasifying agent is one of air or steam; in the step, one part of the separated ash enters a gasification reactor to continue gasification reaction, and the other part of the separated ash enters an ash field to be recycled.

Further, in step 2, the oxygen carrier is a transition metal oxide.

Compared with the prior art, the invention has the following beneficial technical effects:

the gasification reactor, the fuel reactor and the air reactor adopted in the system have simple structures, can be flexibly adjusted in scale, and are suitable for disposing small-scale domestic garbage in small cities, counties or villages and towns; compared with the direct reaction of solid garbage, the domestic garbage is pyrolyzed and gasified to generate gaseous pyrolysis gas, so that the reaction rate of chemical chain combustion can be increased, the pyrolysis gas reaction is promoted to be complete, the equipment abrasion can be effectively reduced, the service life of the reactor is prolonged, most heavy metals are fixed in ash residues after pyrolysis and gasification, the leaching toxicity is low, and the treatment cost is relatively low; chemical looping combustion of gasification gas can convert N element into N₂Part of S elements are self-solidified, and pollutants such as N/S/Cl and the like contained in the gasified gas are removed, so that the clean treatment of the household garbage is realized; meanwhile, in the invention, limestone is adopted to remove oxysulfide in the tail gas, an SNCR spray gun is adopted to remove nitric oxide in the tail gas, and chemical chain combustion is adopted to inhibit the generation of dioxin, so that the tail gas can meet the emission requirement and can be directly discharged into the atmosphere.

Further, the pyrolysis gas is combusted in the fuel reactor, the oxygen carrier is generally transition metal oxide, certain reduction products of the oxygen carrier such as metal Fe or low-valent oxide thereof, metal Ni and the like can catalyze and crack tar, reduce tar content and generate clean carbon dioxide and water, and the phenomena that a large amount of tar is generated in the pyrolysis and gasification process of household garbage, so that pipelines are easily blocked and the inner wall of the reactor is easily polluted are effectively avoided; simultaneously, the oxygen carrier can be recycled, and the material consumption can be reduced.

Drawings

Fig. 1 is a schematic structural diagram of a system according to an embodiment of the present invention.

In the figure: 1 is domestic waste, 2 is the storage silo, 3 is screw feeder, 4 is gasification reactor, 5 is the gasification agent entry, 6 is first separator, 7 is the lime-ash export, 8 is pyrolysis gas, 9 is the oxygen carrier entry, 10 is fuel reactor, 11 is the lime stone, 12 is the second separator, 13 is the SNCR spray gun, 14 is the tail gas export, 15 is the oxygen carrier, 16 is air inlet, 17 is air reactor, 18 is the third separator, 19 is the nitrogen gas export.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention relates to a system for household garbage pyrolysis gasification cooperated chemical chain combustion, which comprises a storage bin 2 and a screw feeder 3 which are sequentially connected with a material inlet of a gasification reactor 4, a gasifying agent inlet 5 positioned at the bottom of the gasification reactor 4, a first separator 6 connected with a pyrolysis gas outlet of the gasification reactor 4, an ash outlet 7 arranged at the bottom of the first separator 6, a fuel reactor 10 connected with the first separator 6, an air reactor 17 internally provided with an oxygen carrier 15 and communicated with the fuel reactor 10 through a second separator 12, an air inlet 16 arranged at the bottom of the air reactor 17, and a third separator 18 connected with the air reactor 17, wherein the air reactor 10 is provided with a first separator 12; an oxygen carrier inlet 9 arranged at the bottom of the fuel reactor 10, a limestone inlet 11 arranged on the side wall of the fuel reactor 10, an SNCR spray gun 13 arranged on the side wall of the second separator 12, and a tail gas outlet 14 arranged at the top of the second separator 12 and a nitrogen outlet 19 arranged at the top of the third separator 18 respectively;

wherein, the domestic garbage in the storage bin 2 is sent into a gasification reactor 4 by a screw feeder 3 and is chemically reacted with a gasification agent. The gasifying agent is generally air or steam and is introduced from a gasifying agent inlet 5 at the bottom of the gasification reactor 4. A part of garbage in the gasification reactor 4 is combusted to provide heat to maintain the gasification reaction temperature;

wherein the domestic garbage is gasified to generate a mixture of pyrolysis gas and ash, wherein the pyrolysis gas is generated by the following reaction 2CH_xO_y+(1-y)O₂→2CO+xH₂And then gas-solid separation is performed in the first separator 6. Introducing the separated pyrolysis gas into a fuel reactor 10; one part of the separated ash enters a gasification reactor 4 for continuous reaction, and the other part of the separated ash is discharged through an ash outlet 7 and then enters an ash field for recycling treatment;

the oxygen carrier 15 is generally a transition metal oxide, in the preferred embodiment, MeO is taken as an example, and Me is a transition metal, such as common red mud. The oxygen carrier 15 is first arranged in the air reactor 17, the oxygen carrier 15 is fed into the fuel reactor 10 through the oxygen carrier inlet 9, and the reduction reaction is carried out on the oxygen carrier 15 and the pyrolysis gas in the fuel reactor 10, and CO + H₂+2MeO→CO₂+H₂And O +2Me, and feeding the reaction product into a second separator. In the second separator 12, the reduced oxygen carrier 15 and the flue gas are subjected to gas-solid separation; under the combined action of the limestone 11 and the SNCR spray gun 13, the flue gas is discharged into the atmosphere through a tail gas outlet 14 after dioxin, oxysulfide and nitric oxide are removed; the reduced oxygen carrier 15 is returned to the air reactor 17;

the oxygen carrier 15 reduced in the air reactor 17 is oxidized with the oxygen in the air reactor 17, 2Me + O₂→ 2MeO, the reaction products enter the third separator 18. In the third separator 18, the oxygen carrier 15 and nitrogen gas are subjected to gas-solid separation, the nitrogen gas is discharged through a nitrogen gas outlet 19, then the oxygen carrier 15 is fed into the fuel reactor 10 through an oxygen carrier inlet 9 to be subjected to reduction reaction with pyrolysis gas, and the process is circulated. Wherein the air is airAn air inlet 16 at the bottom of the reactor 17 opens.

On the basis of the system, the invention also provides a method for the pyrolysis gasification of the household garbage and the synergistic chemical chain combustion, which comprises the following steps:

step 1, feeding the dried and crushed household garbage into a gasification reactor 3, carrying out gasification reaction with a gasification agent to generate a mixture of pyrolysis gas and ash, 2CH_xO_y+(1-y)O₂→2CO+xH₂Gas-solid separation is carried out in the first separator 6, and the pyrolysis gas 8 obtained by separation is introduced into the fuel reactor 10;

step 2, in the fuel reactor 10, the pyrolysis gas 8 and the oxygen carrier 9 are subjected to reduction reaction, and CO + H₂+2MeO→CO₂+H₂The O +2Me, the reaction product enters a second separator 12; in the second separator 12, the reduced oxygen carrier 15 and the tail gas 14 are subjected to gas-solid separation, and the reduced oxygen carrier 15 enters an air reactor 17; the tail gas 14 and the limestone 11 have desulfurization reaction, and the sulfur oxides, CaO and SO in the tail gas are removed₂/SO₃→CaSO₄. The limestone 11 can remove chlorine element simultaneously, CaO +2HCl → CaCl₂+H₂O, since chlorine is an important precursor for dioxin generation, the limestone 11 can significantly suppress the generation of dioxin by removing chlorine. An SNCR lance 13 is arranged on the wall of the second separator 12, into which a reducing agent is injected to reduce the nitrogen oxides, NOx + NH, in the exhaust gas 14₃→N₂+H₂And O. The tail gas from which dioxins, oxysulfides and nitric oxides are removed meets the emission requirements and is directly discharged into the atmosphere through a tail gas outlet 14;

step 3, in the air reactor 17, the reduced oxygen carrier 15 and the oxygen in the air 16 are subjected to oxidation reaction, 2Me + O₂→ 2MeO, the reaction products enter the third separator 18. In the third separator 18, the oxygen carrier 15 and nitrogen gas are subjected to gas-solid separation, the nitrogen gas is discharged through a nitrogen gas outlet 19, the oxygen carrier 15 is sent into the fuel reactor 10, and the

steps

2 and 3 are repeated for circulation;

in the step 1, the gasifying agent is one of air or water vapor.

Wherein, in the step 1, one part of the separated ash enters a gasification reactor 4 for continuous gasification reaction, and the other part of the separated ash enters an ash field for recycling treatment.

In step 2, the oxygen carrier 15 is a transition metal oxide.

Claims

1. a system of domestic waste pyrolysis gasification coordinated chemical chain combustion, is characterized in that, comprises gasification reactor (4), fuel reactor (10) and air reactor (17) connected successively, and respectively a first separator (6), a second separator (12) and a third separator (18) arranged on the gasification reactor (4), the fuel reactor (10) and the air reactor (17);

The gasification reactor (4) is used for pyrolysis of domestic waste; the side wall of the fuel reactor (10) is provided with a limestone inlet (11); the air reactor (17) is provided with several load cells. Oxygen (15);

The inlet of the first separator (6) is communicated with the pyrolysis gas outlet of the gasification reactor (4), and the gas outlet of the first separator (6) is communicated with the gas inlet of the fuel reactor (10);

The inlet of the second separator (12) is communicated with the outlet of the fuel reactor (10), the tail gas outlet (14) of the second separator (12) is discharged into the atmosphere, and the solid outlet of the second separator (12) It is communicated with the inlet of the air reactor (17); the second separator (12) is provided with an SNCR spray gun (13);

The nitrogen outlet (19) of the third separator (18) is discharged into the atmosphere, the inlet of the third separator (18) is communicated with the outlet of the air reactor (17), and the solid outlet of the third separator (18) It communicates with the oxygen carrier inlet (9) of the fuel reactor (10).

2 . The system for cooperating chemical chain combustion of domestic waste pyrolysis and gasification according to claim 1 , wherein the limestone inlet ( 11 ) is arranged on the side wall below the outlet of the fuel reactor ( 10 ). 3 . superior.

3. A device for incinerating domestic waste coupled with coal-fired power generation according to claim 1, wherein the SNCR spray gun (13) is arranged on the opposite side wall of the inlet of the second separator (12), and sprays the Orientation is perpendicular to the side wall.

4. A system for the pyrolysis and gasification of domestic wastes according to claim 1, characterized in that, a gasification agent inlet (5) is provided at the bottom of the gasification reactor (4) , The side wall is provided with a material inlet and an ash inlet.

5. A system for the pyrolysis and gasification of domestic wastes according to claim 4, wherein the material inlet of the gasification reactor (4) is connected with storage bins in sequence. (2) and screw feeder (3).

6 . The system for cooperating chemical chain combustion of domestic waste pyrolysis gasification according to claim 4 , wherein the ash inlet of the gasification reactor ( 4 ) is connected to the first separator ( 6 ). 7 . ) at the bottom of the ash outlet (7).

7 . The system for the pyrolysis and gasification of domestic waste in conjunction with chemical chain combustion according to claim 1 , wherein an air inlet ( 16 ) is provided at the bottom of the air reactor ( 17 ). 8 .

8. A method for coupling coal-fired power generation with domestic waste incineration, based on any one of the devices described in the preceding claims 1-7, characterized in that, comprising the following steps:

In step 1, the domestic waste is sent into the gasification reactor (4), and a mixture of pyrolysis gas and ash residue is generated after gasification reaction with the gasification agent, and gas-solid separation is carried out in the first separator (6), The separated pyrolysis gas is passed into the fuel reactor (10);

Step 2, in the fuel reactor (10), the oxygen carrier (15) undergoes a reduction reaction with the pyrolysis gas (8), and the reaction product enters the second separator (12); in the second separator (12), The reduced oxygen carrier (15) undergoes gas-solid separation from the flue gas; the flue gas passes through the limestone (11) and the SNCR spray gun (13) under the combined action of removing dioxins, sulfur oxides and nitrogen oxides. The tail gas outlet (14) is discharged into the atmosphere; the reduced oxygen carrier (15) enters the air reactor (17);

In step 3, the reduced oxygen carrier (15) in the air reactor (17) enters the third separator (18) after an oxidation reaction with oxygen in the air; in the third separator (18), the oxygen carrier (15) Gas-solid separation occurs with nitrogen, nitrogen is discharged through nitrogen outlet (19), oxygen carrier (15) enters fuel reactor (10) through oxygen carrier inlet (9), and steps 2 and 3 are repeated for circulation.

9 . The method for coordinating chemical chain combustion with domestic waste pyrolysis and gasification according to claim 8 , wherein in step 1, the gasifying agent is one of air or water vapor; step 10 . In 1, a part of the separated ash and slag enters the gasification reactor (4) to continue the gasification reaction, and the other part enters the ash and slag field for recycling.

10 . The method for coordinating chemical chain combustion of domestic waste pyrolysis and gasification according to claim 8 , wherein, in step 2, the oxygen carrier ( 15 ) is a transition metal oxide. 11 .