CN112432180A

CN112432180A - Classified dry garbage pyrolysis staged combustion method and system

Info

Publication number: CN112432180A
Application number: CN202011305073.3A
Authority: CN
Inventors: 袁国安; 陈善平; 张瑞娜; 邰俊; 刘泽庆; 曹瑞杰; 陈德珍
Original assignee: Shanghai Environmental Sanitation Engineering Design Institute Co ltd; Shanghai Institute for Design and Research on Environmental Engineering Co Ltd
Current assignee: Shanghai Environmental Sanitation Engineering Design Institute Co ltd; Shanghai Institute for Design and Research on Environmental Engineering Co Ltd
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-03-02

Abstract

The invention relates to the field of garbage disposal and recycling, in particular to a pyrolysis staged combustion method and system for classified dry garbage. The invention provides a pyrolysis and staged combustion method for classified dry garbage, which comprises the following steps: carrying out pyrolysis treatment on the dry garbage to provide pyrolysis semicoke and pyrolysis volatile stream; subjecting the pyrolysis semicoke to an incomplete combustion reaction with a first air stream to provide a first intermediate stream and slag; performing a post-combustion reaction on the first intermediate stream and a second air stream to provide a second intermediate stream, wherein the second air stream comprises a pyrolysis volatilization stream; the second intermediate stream is subjected to a tertiary combustion reaction with a third air stream to provide a burnout stream. The pyrolysis and staged combustion method and system for classified dry garbage are beneficial to more reasonable, efficient and clean resource utilization of classified garbage, and have good industrialization prospects.

Description

Classified dry garbage pyrolysis staged combustion method and system

Technical Field

The invention relates to the field of garbage disposal and recycling, in particular to a pyrolysis staged combustion method and system for classified dry garbage.

Background

The characteristics of the refuse entering the end facility change significantly in the context of a large classification of refuse. 26.4.2019, the Ministry of housing and urban and rural construction issued a notice (build City [ 2019 ] 56 ] of departments such as Ministry of housing and urban and rural construction about the comprehensive development of the classification of domestic garbage in cities on the national level and above, which indicates that China comprehensively enters the era of forced garbage classification. Forced garbage classification is performed in Shanghai, and the regulations on domestic garbage management (hereinafter referred to as "regulations") in Shanghai City are implemented from 7/1 in 2019. The effect is remarkable since the implementation of regulations, the standard reaching rate of classification of residential areas is improved from 15% in 1 month to 90% in 12 months, the heat value of dry garbage entering end facilities is remarkably improved along with the separation of a large amount of recyclable matters, wet garbage and harmful garbage, the average heat value of the dry garbage in Shanghai city in 2018 is about 2300kcal/kg, and after the implementation of the regulations in 7 months in 2019, the heat value of the garbage in the first month is over 3100kcal/kg, and is improved by about 35% compared with the average value in 2018.

The characteristics of the garbage, particularly the calorific value, are changed, and certain negative effects are brought to the stable operation of the existing incineration facility. Therefore, more reasonable incineration equipment is needed to be provided according to the characteristics of the garbage, so that more reasonable, efficient and clean resource utilization is guaranteed.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a classified dry refuse pyrolysis staged combustion method and system for solving the problems of the prior art.

To achieve the above and other related objects, according to one aspect of the present invention, there is provided a classified dry garbage pyrolysis staged combustion method, comprising:

1) carrying out pyrolysis treatment on the dry garbage to provide pyrolysis semicoke and pyrolysis volatile stream;

2) subjecting the pyrolysis semicoke provided in step 1) to an incomplete combustion reaction with a first air stream to provide a first intermediate stream and slag;

3) performing a secondary combustion reaction on the first intermediate stream provided in the step 2) and a second air stream to provide a second intermediate stream, wherein the second air stream comprises the pyrolysis volatilization stream provided in the step 1);

4) subjecting the second intermediate stream provided in step 3) to a tertiary combustion reaction with a third air stream to provide a burnout stream.

In some embodiments of the present invention, in the step 1), the pyrolysis temperature of the pyrolysis treatment is 250 to 800 ℃.

In some embodiments of the invention, in step 1), at least part of the heat source for the pyrolysis process is from the burnout stream.

In some embodiments of the invention, in step 1), the pyrolysis volatilization stream comprises a reducing gas selected from CO, H₂And a hydrocarbon comprising CH₄The pyrolysis volatilization stream further comprises CO₂Wherein the content of CO is 10-35 v/v%, H₂In an amount of 2-30 v/v%, CH₄The content of (A) is 1-20 v/v%, CO₂The content of (b) is 30-60 v/v%.

In some embodiments of the invention, in step 1), the dry waste is the dry waste after being subjected to a crushing treatment.

In some embodiments of the present invention, in the step 2), the air excess coefficient α is 0.3 to 1.0.

In some embodiments of the invention, the heat decreasing rate in step 2) is less than or equal to 3%.

In some embodiments of the invention, said step 2) wherein the first intermediate stream comprises CO, H₂、CH₄、CO₂And N₂Wherein the content of CO is 4-30 v/v%, H₂In an amount of 2-20 v/v%, CH₄The content of (A) is 0.1-6 v/v%, CO₂The content of (A) is 5-15 v/v%, N₂The content of (b) is 40-75 v/v%.

In some embodiments of the present invention, in the step 3), the air excess coefficient α is 1.0 to 1.3.

In some embodiments of the invention, in the step 3), the proportion of the pyrolysis volatilization stream in the second air stream is 5-20 v/v%.

In some embodiments of the invention, the step 3) comprises the second intermediate stream comprising CO₂Water vapor, N₂And O₂Wherein, CO₂The content of (A) is 10-20 v/v%, N₂The content of (A) is 50-70 v/v%, the content of water vapor is 5-30 v/v%, O₂The content of (b) is 9-15 v/v%.

In some embodiments of the present invention, the air excess factor in step 4) is 1.1 ≦ α ≦ 1.3.

In some embodiments of the invention, in step 4), the burnout stream comprises CO₂Water vapor, N₂And O₂Wherein, CO₂The content of (A) is 10-20 v/v%, N₂The content of (A) is 50-70 v/v%, the content of water vapor is 5-30 v/v%, O₂The content of (b) is 10-17 v/v%.

In some embodiments of the invention, the classified dry refuse pyrolysis staged combustion method further comprises:

5) and (3) carrying out dust removal treatment and/or deacidification treatment on the burnout stream provided by the step 4).

In another aspect, the present invention provides a classified dry garbage pyrolysis staged combustion system, comprising:

the pyrolysis device is used for carrying out pyrolysis treatment on the dry garbage to provide pyrolysis semicoke and pyrolysis volatile flow;

the staged combustion device is used for carrying out staged combustion treatment on the pyrolysis semicoke;

the staged combustion device sequentially comprises the following components in the fluid flowing direction:

a combustion gasification zone for subjecting the pyrolysis semicoke to an incomplete combustion reaction with a first air stream to provide a first intermediate stream and slag;

a secondary combustion zone for carrying out a secondary combustion reaction on the first intermediate stream and a second air stream to provide a second intermediate stream, wherein the second air stream comprises a pyrolysis volatilization stream;

a burnout zone for subjecting the second intermediate stream to a tertiary combustion reaction with a third air stream to provide a burnout stream.

In some embodiments of the present invention, the staged combustion device comprises, from bottom to top, a combustion gasification zone, a secondary combustion zone, and a burnout zone.

In some embodiments of the present invention, a burnout stream return conduit is disposed on the pyrolysis apparatus, the burnout stream return conduit being in fluid communication with the pyrolysis apparatus and the burnout zone, respectively.

In some embodiments of the present invention, the classified dry garbage pyrolysis staged combustion system further comprises a crushing device for crushing the dry garbage.

In some embodiments of the present invention, the classified dry garbage pyrolysis staged combustion system further comprises a dust removal device and/or a deacidification device for performing a dust removal treatment and/or a deacidification treatment on the burnout stream.

Drawings

FIG. 1 is a schematic view of the process flow in example 1 of the present invention.

Description of the element reference numerals

1 Dry garbage

2 storage pit

3 odor control device

4 crushing device

5 conveying device

6 pyrolysis device

7 staged combustion device

8 fire grate

9 combustion gasification zone

10 secondary combustion zone

11 burnout zone

12 dust removing device

13 deacidifying device

14 smoke draught fan

15 combustion air supply fan

16 regulating valve

17 slag

18 fly ash

19 chimney

a1 first air stream

a2 second air stream

a3 third air stream

g1 high-temperature flue gas

g2 high-temperature flue gas after dust removal

g3 flue gas after splitting of pyrolysis device

g4 heating pyrolysis device flue gas

g5 flue gas after heat-clearing pyrolysis device

g6 Pre-Deacidification Smoke

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments, and other advantages and effects of the present invention will be apparent to those skilled in the art from the disclosure of the present specification.

The inventor of the invention provides a classified dry garbage pyrolysis staged combustion method and further provides a related classified dry garbage pyrolysis staged combustion system through a large amount of practical researches, the pyrolysis staged combustion method integrally divides the treatment process of classified dry garbage into three links of pyrolysis, gasification and volatile component combustion, thereby effectively solving a series of problems of hearth coking, aggravation of corrosion, reduction of grate service life and the like which are possibly caused in the treatment process of classified dry garbage, and the invention is completed on the basis.

The invention provides a classified dry garbage pyrolysis staged combustion method, which comprises the following steps:

In the pyrolysis staged combustion method for classified dry garbage provided by the invention, the dry garbage can be other domestic wastes except recyclable matters, harmful garbage and wet garbage, and can generally comprise paper, plastics, glass, metal, fabrics and the like. The dry garbage treated by the invention generally has higher heat value, for example, the heat value can be 8000-14000 kJ/kg, 8000-9000 kJ/kg, 9000-10000 kJ/kg, 10000-11000 kJ/kg, 11000-12000 kJ/kg, 12000-13000 kJ/kg or 13000-14000 kJ/kg. The treated dry garbage can also be the dry garbage subjected to crushing treatment, so that the materials can meet the furnace charging requirement and the unsmooth feeding and slag discharging cannot be caused in the subsequent treatment. For example, the size of the dry waste after being subjected to the crushing process (e.g., the diameter of the mass) can typically be 100cm or less, 50cm or less, or 30cm or less, to meet minimum requirements for stable feed and tapping at the feed inlet. Generally, the smaller the size of the dry waste, the more favorable the pyrolysis reaction proceeds, but the cost is increased by excessive crushing treatment, so that the crushing efficiency is generally considered.

The classified dry garbage pyrolysis staged combustion method provided by the invention can comprise the following steps: the dry waste is subjected to a pyrolysis treatment to provide a pyrolysis semicoke and a pyrolysis volatile stream. Pyrolysis treatment generally refers to a treatment process in which dry waste is subjected to substantially oxygen-free, elevated temperature conditions such that the dry waste is dewatered, pyrolyzed, and produces a combustible pyrolysis volatile stream and pyrolysis char. For example, the pyrolysis temperature of the pyrolysis treatment may be 250 to 800 ℃, 250 to 300 ℃, 300 to 350 ℃, 350 to 400 ℃, 400 to 450 ℃, 450 to 500 ℃, 500 to 550 ℃, 550 to 600 ℃, 600 to 650 ℃, 650 to 700 ℃, 700 to 750 ℃, or 750 to 800 ℃. The pyrolysis time can be adjusted by those skilled in the art, and the pyrolysis time generally varies according to the material characteristics and scale, and is generally less than or equal to 1 hour, 10-20 min, 20-30 min, 30-40 min, 40-50 min, or 50-60 min. Generally, the pyrolysis volatile stream provided by the pyrolysis process is primarily a gaseous product that may include primarily a reducing gas, such as CO, H, or the like₂And hydrocarbon (CxHy), etc., which may be, for example, CH₄Etc., the pyrolysis volatilization stream further comprising CO₂And the like. The content of CO in the pyrolysis volatilization stream can be 10-35 v/v%, 10-15 v/v%, 15-20 v/v%, 20-25 v/v%, 25-30 v/v%, or 30-35 v/v%, H₂The content of (b) may be 2-30 v/v%, 2-4 v/v%, 4-6 v/v%, 6-8 v/v%, 8-10 v/v%, 10-15 v/v%, 15-20 v/v%, 20-25 v/v%, or 25-30 v/v%, CH₄The content of (b) may be 1 to 20 v/v%, 1 to 2 v/v%, 2 to 4 v/v%, 4 to 6 v/v%, 6 to 8 v/v%, 8 to 10 v/v%, 10 to 12 v/v%, 12 to 14 v/v%, 14 to 16 v/v%, 16 to 18 v/v%, or 18 to 20 v/v%, excluding CH₄The content of other hydrocarbons is usually 10 v/v% or less, or 5 v/v% or less, CO₂The content of (b) may be 30 to 60 v/v%, 30 to 35 v/v%, 35 to 40 v/v%, 40 to 45 v/v%, 45 to 50 v/v%, 50 to 55 v/v%, or 55 to 60 v/v%. The pyrolysis semicoke provided by the pyrolysis treatment is mainly a solid product, wherein the pyrolysis semicoke mainly comprises pyrolysis carbon and can also comprise a small amount of heavy tar and the like.

The classified dry garbage pyrolysis staged combustion method provided by the invention can comprise the following steps: subjecting the pyrolysis semicoke provided in step 1) to an incomplete combustion reaction with a first air stream to provide a first intermediate stream and slag. The pyrolysis semicoke can be subjected to incomplete combustion reaction (primary combustion) with the first air stream, the combustion speed and the temperature level are reduced due to insufficient oxygen, the thermal NOx is reduced, nitrogen in the fuel is decomposed to generate a large amount of intermediate products NHi and HCN, a part of NOx is reduced, and the generation of the fuel NOx is inhibited. The incomplete combustion reaction of the pyrolysis semicoke with the first air stream is mainly reflected in its gaseous products, i.e. there are still combustible gaseous substances and/or fine particulate matter (e.g. CO, H) present in the first intermediate stream (gaseous product) provided by the reaction₂、CH₄Etc.) and the slag (solid product) provided by the reaction is the product of complete combustion. Generally, the major components of the first intermediate stream can comprise CO, H₂、CH₄、CO₂And N₂And the content of CO in the first intermediate stream can be 4-30 v/v%, 4-6 v/v%, 6-8 v/v%, 8-10 v/v%, 10-12 v/v%, 12-14 v/v%, 14-16 v/v%, 16-18 v/v%, 18-20 v/v%, 20-22 v/v%, 22-24 v/v%, 24-26 v/v%, 26-28 v/v%, or 28-30 v/v%, H₂The content of (b) is 2-20 v/v%, 2-4 v/v%, 4-6 v/v%6-8 v/v%, 8-10 v/v%, 10-12 v/v%, 12-14 v/v%, 14-16 v/v%, 16-18 v/v%, or 18-20 v/v%, CH₄The content of (b) may be 0.1 to 6 v/v%, 0.1 to 0.3 v/v%, 0.3 to 0.5 v/v%, 0.5 to 1 v/v%, 1 to 2 v/v%, 2 to 3 v/v%, 3 to 4 v/v%, 4 to 5 v/v%, or 5 to 6 v/v%, CO₂The content of (b) may be 10-15 v/v%, 10-11 v/v%, 11-12 v/v%, 12-13 v/v%, 13-14 v/v%, or 14-15 v/v%, N₂The content of (b) may be 40-75 v/v%, 40-45 v/v%, 45-50 v/v%, 50-55 v/v%, 55-60 v/v%, 60-65 v/v%, 65-70 v/v%, or 70-75 v/v%. The slag mainly comprises slag soil, ash and the like. In the primary combustion process, generally speaking, a higher temperature is required in the combustion area to improve the gasification intensity, and on the other hand, the temperature is higher due to the violent release of heat in the gasification process because the pyrolytic coke has a higher energy density. For example, the central temperature of the combustion zone may be generally 900 ℃ or higher, 900 to 1000 ℃, 1000 to 1100 ℃, 1100 to 1200 ℃ or higher. The excess air ratio in the primary combustion process is usually not more than 1, that is, the amount of air actually supplied is not more than the theoretical amount of air, and for example, the excess air ratio α in the primary combustion process may be 0.3 to 1.0, 0.3 to 0.4, 0.4 to 0.5, 0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 0.9, or 0.9 to 1.0. In addition, a smaller heat override rate is generally required for a single combustion event. For example, the heat turndown rate in the primary combustion process may be 3 or less, or 2 or less.

The classified dry garbage pyrolysis staged combustion method provided by the invention can comprise the following steps: performing a secondary combustion reaction on the first intermediate stream provided in the step 2) and a second air stream to provide a second intermediate stream, wherein the second air stream comprises the pyrolysis volatilization stream provided in the step 1). The pyrolysis volatilization stream included in the second air stream can provide reducing conditions for the post-combustion reaction, which takes place in full combustion reaction with the first intermediate stream, where the fuel can generate hydrocarbon radicals at high temperature and reducing atmosphere, which can react with NOx in the first intermediate stream (resulting from the primary combustion)Generating N₂The NOx content in the flue gas is further reduced, e.g. the NOx content in the second intermediate stream is typically 250mg/Nm or less³. Further, a major component of the second intermediate stream can comprise CO₂Water vapor, N₂And O₂Etc. in the second intermediate stream, CO₂The content of (b) may be 10-20 v/v%, 10-12 v/v%, 12-14 v/v%, 14-16 v/v%, 16-18 v/v%, or 18-20 v/v%, N₂The content of (b) may be 50-70 v/v%, 50-55 v/v%, 55-60 v/v%, 60-65 v/v%, or 65-70 v/v%, the content of water vapor may be 5-30 v/v%, 5-10 v/v%, 10-15 v/v%, 15-20 v/v%, 20-25 v/v%, or 25-30 v/v%, O₂The content of (b) may be 9-15 v/v%, 9-10 v/v%, 10-11 v/v%, 11-12 v/v%, 12-13 v/v%, 13-14 v/v%, or 14-15 v/v%. In the secondary combustion process, the temperature in the combustion zone generally cannot be too low, so as to achieve the purpose of fully combusting and controlling dioxin, for example, the central temperature of the combustion zone can be generally equal to or higher than 850 ℃, 850-900 ℃, 900-950 ℃ or higher. The excess air ratio in the secondary combustion process is usually not less than 1, that is, the amount of air actually supplied is not less than the theoretical amount of air in total, and for example, the excess air ratio α in the secondary combustion process may be 1.0 to 1.3, 1.0 to 1.05, 1.05 to 1.1, 1.1 to 1.15, 1.15 to 1.2, 1.2 to 1.25, or 1.25 to 1.3. In the secondary combustion process, the proportion of the pyrolysis volatilization stream in the second air stream can be 5-20 v/v%, 5-10 v/v%, 10-15 v/v% and 15-20 v/v%.

The classified dry garbage pyrolysis staged combustion method provided by the invention can comprise the following steps: subjecting the second intermediate stream provided in step 3) to a tertiary combustion reaction with a third air stream to provide a burnout stream. In the third combustion reaction, residual CO and hydrocarbon are mainly combusted, a small amount of NOx can be generated in the burnout process, the composition of flue gas is basically not changed, and the oxygen content is slightly increased. Specifically, the burnout stream can include CO₂Water vapor, N₂And O₂Etc., burnout of the stream, CO₂The content of (b) can be 10-20 v/v% or 10-12 v%v%, 12-14 v/v%, 14-16 v/v%, 16-18 v/v%, or 18-20 v/v%, N₂The content of (b) may be 50-70 v/v%, 50-55 v/v%, 55-60 v/v%, 60-65 v/v%, or 65-70 v/v%, the content of water vapor may be 5-30 v/v%, 5-10 v/v%, 10-15 v/v%, 15-20 v/v%, 20-25 v/v%, or 25-30 v/v%, O₂The content of (b) may be 10-17 v/v%, 10-11 v/v%, 11-12 v/v%, 12-13 v/v%, 13-14 v/v%, 14-15 v/v%, 15-16 v/v%, 16-17 v/v%. In the third combustion process, generally, the temperature in the combustion area cannot be too low, and the smoke needs to stay in the combustion area for enough time, so that the purpose of burning out the residual trace combustible substances is achieved. For example, the core temperature of the combustion zone may be generally at temperatures of 850 ℃ or more, 850 to 900 ℃ or 900 to 950 ℃ or more, and for example, the residence time of the flue gas in the combustion zone may generally be 1.5 seconds or more, 2 seconds or more, or 2.5 seconds or more. The excess air ratio in the tertiary combustion process is usually not less than 1, that is, the amount of air actually supplied is not less than the theoretical amount of air, and for example, the excess air ratio in the tertiary combustion process may be 1.3 or less, 1.1 to 1.15 or less, 1.15 to 1.2 or 1.2 to 1.25 or 1.25 to 1.3.

In the classified dry garbage pyrolysis staged combustion method provided by the invention, at least part of the heat source for pyrolysis treatment can come from an burnout stream. Generally speaking, the temperature of the burnout stream provided by the third combustion reaction may be 300-900 ℃, 300-400 ℃, 400-500 ℃, 500-600 ℃, 600-700 ℃, 700-800 ℃, or 800-900 ℃. The heat of the high-temperature burnout stream can be recycled and used for heating the dry garbage in the pyrolysis treatment.

The pyrolysis staged combustion method for classified dry garbage provided by the invention can also comprise the following steps: and (3) carrying out dust removal treatment and/or deacidification treatment on the burnout stream provided by the step 4). Typically, the burnout stream will include a certain amount of dust and NOx, so some post-treatment of the burnout stream is required before discharge or recycling (e.g., heat sources used for pyrolysis processes, etc.). Suitable methods for dedusting and/or deacidifying the burn-up stream areAs should be known to those skilled in the art. For example, the dust removal treatment may be performed by a method such as cyclone dust removal. For example, the deacidification treatment may be carried out by a method such as alkali spraying. In general, the NOx content of the product obtained after the deacidification treatment may be 100mg/Nm or less³、≤90mg/Nm³、≤80mg/Nm³、≤70mg/Nm³、≤60mg/Nm³、≤50mg/Nm³。

The invention provides a classified dry garbage pyrolysis staged combustion system, which comprises:

The classified dry garbage pyrolysis staged combustion system provided by the invention can comprise a pyrolysis device, wherein the pyrolysis device is generally used for carrying out pyrolysis treatment on dry garbage to provide pyrolysis semicoke and pyrolysis volatile streams. The pyrolysis apparatus may typically be a pyrolysis furnace or the like. The pyrolysis plant may generally be provided with a feed inlet, a pyrolysis semicoke discharge outlet, a pyrolysis volatile stream lead-out conduit, etc., so that the pyrolysis-treated feedstock may be led into the pyrolysis plant and the treated product may be further led out of the pyrolysis plant.

The classified dry garbage pyrolysis staged combustion system provided by the invention can comprise a staged combustion device, wherein the staged combustion device is usually used for carrying out staged combustion treatment on pyrolysis semicoke, namely carrying out incomplete combustion reaction, secondary combustion reaction and tertiary combustion reaction in sequence. The staged combustion device can correspondingly comprise a combustion gasification zone, a secondary combustion zone and a burnout zone in sequence according to the flowing direction of fluid, generally speaking, the staged combustion device can comprise continuous combustion zones (namely the three combustion zones of the combustion gasification zone, the secondary combustion zone and the burnout zone are basically a complete cavity), the combustion zones sequentially comprise the combustion gasification zone, the secondary combustion zone and the burnout zone from bottom to top, and gas in the combustion zones can flow from bottom to top.

In the staged combustion device, each combustion zone is usually matched with other devices, so that the pyrolysis semicoke can be subjected to staged combustion treatment. For example, the combustion gasification zone may be generally provided with a feed inlet in cooperation with a pyrolysis apparatus, the combustion gasification zone in the staged combustion apparatus may be generally communicated with the pyrolysis apparatus so that the pyrolysis semicoke may be introduced into the combustion gasification zone and subjected to an incomplete combustion reaction with the first air stream, a first air stream introduction passage may be further provided so as to introduce the first air stream, and the like. For another example, the secondary combustion zone is generally provided with a second air stream introduction passage that is generally in fluid communication with a pyrolysis device (e.g., a pyrolysis volatiles stream take off conduit) such that a second air stream comprising a pyrolysis volatiles stream can be introduced into the secondary combustion zone. As another example, the burnout zone may be generally provided with a third air stream introduction passage or the like to introduce the third air stream.

According to the classified dry garbage pyrolysis staged combustion system provided by the invention, the pyrolysis device is provided with the burnout stream backflow pipeline, and the burnout stream backflow pipeline is respectively communicated with the pyrolysis device and the burnout area through fluid. A burnout stream return line can generally be used to communicate the pyrolysis plant with the burnout zone so that the burnout stream can be recycled as a heat source for introduction into the pyrolysis plant.

The classified dry garbage pyrolysis and staged combustion system provided by the invention can also comprise a crushing device for crushing dry garbage. Dry waste (e.g., dry waste placed in a waste storage pit) may be introduced into the crushing device, sufficiently crushed, directed out of the crushing device, and further directed into the pyrolysis device. The crushing device may generally be a crusher or the like of various suitable sizes.

The classified dry garbage pyrolysis staged combustion system provided by the invention can also comprise a dust removal device and/or a deacidification device, and is used for performing dust removal treatment and/or deacidification treatment on the burnout streams. The de-dusting apparatus and/or the deacidification apparatus may generally be in fluid communication with a burnout zone, e.g., the burnout zone may be in fluid communication with the de-dusting apparatus and the deacidification apparatus in sequence, and the burnout stream exiting from the burnout zone may be directed into the de-dusting apparatus and the deacidification apparatus in sequence. For another example, the burnout stream return line may be in fluid communication with a line between the dust removal device and the deacidification plant, the burnout stream drawn from the burnout zone may be recycled after the dust removal process, introduced to the pyrolysis device, and the burnout stream after the heat source is absorbed may be further introduced to the deacidification plant for subsequent processing and discharge. The burnout stream can be introduced to a dust removal unit and/or a deacidification unit prior to discharge or recycling (e.g., a heat source used for pyrolysis, etc.), so that dust entrained in the stream can be removed and the NOx content of the stream can be reduced to meet emission standards. The dust removing means may be, for example, a cyclone dust remover or the like. The deacidification device can be, for example, a lye spraying device or the like.

The classified dry garbage pyrolysis staged combustion system provided by the invention can also comprise a deodorization device, and the deodorization device is used for introducing gas in the crushing device and/or the garbage storage pit into the combustion gasification region and/or the burnout region, so that the aim of deodorization is fulfilled. For example, the first air stream and/or the third air stream may comprise gas drawn from the crushing plant and/or the waste storage pit. The deodorizing means may typically be in fluid communication with the crushing means and/or the waste storage pit, and may also be in fluid communication with the combustion gasification zone and/or the burnout zone. The deodorising means may typically be a fan or the like for drawing gas from the crushing means and/or the waste storage pit.

The pyrolysis staged combustion method and the pyrolysis staged combustion system for the classified dry garbage can be suitable for the classified dry garbage with higher heat value, and can avoid the local over-temperature phenomenon inside a hearth and on the surface of a grate in the treatment process, so that a series of problems of hearth coking, aggravation of corrosion, reduction of the service life of the grate and the like possibly caused in the treatment process of the classified dry garbage are effectively solved, the pyrolysis staged combustion method and the pyrolysis staged combustion system for the classified dry garbage have the characteristics of good operation stability, good economy and the like, are beneficial to more reasonable, efficient and clean resource utilization of the classified garbage, and have good industrialization prospects.

The invention of the present application is further illustrated by the following examples, which are not intended to limit the scope of the present application.

Example 1

As shown in fig. 1, the dry garbage classification pyrolysis system mainly includes a crushing device 4 (crusher), a pyrolysis device 6 (pyrolysis furnace), a staged combustion device 7, a dust removal device 12 (cyclone), a deacidification device 13, and the like.

(1) Receiving, crushing and transmitting materials, wherein after the dry garbage 1 enters the storage pit 2, the dry garbage can be conveyed into a crushing device 4 by a conveying device (or a grab bucket), and the size of the crushed dry garbage is smaller than 50 cm; the crushed dry garbage is conveyed into a pyrolysis device 6 through a conveying device 5.

(2) And (3) pyrolyzing the dry garbage, wherein the treatment capacity of the dry garbage is 100 tons/day, the crushed dry garbage is subjected to processes of temperature rise, dehydration, pyrolysis and the like in a pyrolysis device 6 for the second time to generate pyrolysis semicoke and pyrolysis volatile matters (including gas and other gaseous substances under high-temperature conditions), the temperature range in the pyrolysis device is 350-450 ℃, and the pyrolysis time (namely the retention time of the materials in the furnace) is 45 minutes. The pyrolysis semicoke is discharged from the end of the pyrolysis plant and fed into the staged combustion chamber 7 and the pyrolysis volatiles are fed into the secondary combustion zone 10 as a second air stream (overfire air) a 2. The pyrolysis device 6 is heated by high-temperature flue gas g4 after combustion, and the flue gas g5 after passing through the pyrolysis device is converged into a flue gas purification line g 6.

(3) The pyrolysis semicoke is combusted in a grading way, after the pyrolysis semicoke enters a grading combustion device 7, firstly, a gasification reaction is carried out in a combustion gasification area 9 above the surface of a grate 8, the gasification temperature is 900-1100 ℃, the time is about 10 minutes, the air supply quantity of a first air stream (primary air) a1 is about 0.4 of the theoretical air quantity of dry garbage combustion, and fully oxidized slag 17 and gasified air are generated through gasification; the gasified gas and a second air flow (secondary air) a2(1500Nm3 air/t garbage, the volatile component is about 200Nm3) are subjected to secondary combustion in a secondary combustion area, and the combustion temperature is 900-1200 ℃; the smoke generated by secondary combustion enters an burnout zone, and residual combustible substances in the smoke are completely combusted through a third air stream (tertiary air and burnout air) a3(200Nm3 air/t garbage), wherein the combustion temperature is about 1100 ℃. The residence time of the flue gas in the secondary combustion zone and the burnout zone is about 2-4 s.

(4) The flue gas purification, the high temperature flue gas g1 that staged combustion device produced, once through dust collector 12, deacidification device 13, draught fan 14, then discharge into the environment through chimney 19. 1) The fly ash 18 is generated after the flue gas g1 passes through the dust removal device 12, the fly ash is treated according to the fly ash incineration requirement, the flue gas g2 after dust removal is divided into g3 and g4, the g4 is used for heating the pyrolysis device 6, and g3 and g5 are converged into g6 and introduced into the deacidification device 13; 2) the deacidification device 13 adopts alkali liquor for spraying to remove HCl and SO in the flue gas₂Removing; 3) the purified flue gas g7 reaching the standard is sent into a chimney 19 through a draught fan 14 and discharged into the environment, and the standard of GB18485 is met.

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A pyrolysis staged combustion method for classified dry garbage comprises the following steps:

2. The classified dry garbage pyrolysis staged combustion method according to claim 1, wherein in the step 1), the pyrolysis temperature of the pyrolysis treatment is 250-800 ℃;

and/or, in the step 1), at least part of the heat source of the pyrolysis treatment comes from the burnout stream;

and/or, in the step 1), the pyrolysis volatilization stream comprises a reducing gas selected from CO and H₂And a hydrocarbon comprising CH₄The pyrolysis volatilization stream further comprises CO₂Wherein the content of CO is 10-35 v/v%, H₂In an amount of 2-30 v/v%, CH₄The content of (A) is 1-20 v/v%, CO₂The content of (a) is 30-60 v/v%;

and/or, in the step 1), the dry garbage is subjected to crushing treatment.

3. The classified dry garbage pyrolysis staged combustion method according to claim 1, wherein in the step 2), the excess air coefficient α is 0.3 to 1.0;

and/or, in the step 2), the heat decreasing rate is less than or equal to 3 percent;

and/or, in the step 2), the first intermediate stream comprises CO and H₂、CH₄、CO₂And N₂Wherein the content of CO is 4-30 v/v%, H₂In an amount of 2-20 v/v%, CH₄The content of (A) is 0.1-6 v/v%, CO₂The content of (A) is 5-15 v/v%, N₂The content of (b) is 40-75 v/v%.

4. The classified dry garbage pyrolysis staged combustion method according to claim 1, wherein in the step 3), the excess air coefficient α is 1.0 to 1.3;

and/or in the step 3), the proportion of the pyrolysis volatile stream in the second air stream is 5-20 v/v%;

and/or, in step 3), the second intermediate stream comprises CO₂Water vapor, N₂And O₂Wherein, CO₂The content of (A) is 10-20 v/v%, N₂The content of (A) is 50-70 v/v%, the content of water vapor is 5-30 v/v%, O₂The content of (a) is 9-15 v/v%;

and/or in the step 4), the excess air coefficient alpha is more than or equal to 1.1 and less than or equal to 1.3;

and/or, in the step 4), the burnout stream comprises CO₂Water vapor, N₂And O₂Wherein, CO₂The content of (A) is 10-20 v/v%, N₂The content of (A) is 50-70 v/v%, the content of water vapor is 5-30 v/v%, O₂The content of (b) is 10-17 v/v%.

5. The classified dry refuse pyrolytic staged combustion method according to claim 1, further comprising:

6. A classified dry waste pyrolysis staged combustion system, comprising:

7. The classified dry garbage pyrolysis and staged combustion method as claimed in claim 1, wherein the staged combustion device comprises a combustion gasification zone, a secondary combustion zone and a burnout zone in sequence from bottom to top.

8. The sorted dry refuse pyrolytic staged combustion method according to claim 1, wherein an burnout stream return conduit is provided on the pyrolysis plant, the burnout stream return conduit being in fluid communication with the pyrolysis plant and the burnout zone, respectively.

9. The classified dry waste pyrolytic staged combustion system of claim 1, further comprising a crushing device for crushing dry waste.

10. The staged combustion system for staged dry waste pyrolysis according to claim 1, further comprising a de-dusting and/or de-acidifying device for de-dusting and/or de-acidifying the burnout stream.