CN114907883A

CN114907883A - Solid waste treatment method and system

Info

Publication number: CN114907883A
Application number: CN202110169501.2A
Authority: CN
Inventors: 宋文健; 鲁思达; 杨科; 薛康; 谢星; 李碧云; 王静
Original assignee: Beijing Aerospace Innovation Patent Investment Center (limited Partnership); Xi'an Aerospace Yuan Dongli Engineering Co ltd
Current assignee: Beijing Aerospace Innovation Patent Investment Center (limited Partnership); Xi'an Aerospace Yuan Dongli Engineering Co ltd
Priority date: 2021-02-07
Filing date: 2021-02-07
Publication date: 2022-08-16

Abstract

The invention discloses a solid waste treatment method and a solid waste treatment system. The solid waste treatment method comprises the following steps: pretreating solid waste; carrying out pressure gasification on solid waste gasification raw materials in a fixed bed slag gasification furnace by using oxygen-containing gas and steam as gasification agents to generate crude synthesis gas; and (3) carrying out pressure gasification on the raw synthesis gas and the coal water slurry in the presence of oxygen in a coal water slurry gasification furnace to obtain synthesis gas.

Description

Solid waste treatment method and system

Technical Field

The invention belongs to the technical field of solid waste treatment, and particularly relates to a solid waste treatment method and a solid waste treatment system.

Background

Solid waste (referred to as solid waste) is solid or semi-solid waste generated in the production and living processes of human beings, and comprises domestic garbage, sewage treatment sludge, agricultural production waste, hazardous waste and the like. With the development of socio-economic, the amount of solid waste generated every year is increasing. The treatment of solid wastes is related to the sustainable utilization of resources and the sustainable development of society, so that more and more attention is paid to the solid wastes.

The current solid waste treatment process mainly comprises landfill treatment, incineration treatment and gasification melting treatment. The landfill treatment and the incineration treatment have the problems of large pollution and resource waste. The gasification and melting treatment is a resource solid waste treatment process for converting carbon-containing substances in solid waste into useful synthetic gas through gasification. However, the solid waste has a very low calorific value and a very complex composition, which often results in an unstable gasification process, and the obtained synthesis gas has a very high content of organic impurities, and is difficult to purify in the subsequent process.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides a solid waste treatment method, which includes the following steps:

pretreating solid waste to obtain a solid waste gasification raw material with a heat value of more than or equal to 3000kJ/kg and a water content of less than or equal to 40%;

carrying out pressure gasification on solid waste gasification raw materials in a fixed bed slag gasification furnace by using oxygen-containing gas and steam as gasification agents to generate crude synthesis gas;

and (3) carrying out pressure gasification on the raw synthesis gas and the coal water slurry in the presence of oxygen in a coal water slurry gasification furnace to obtain synthesis gas.

A second aspect of the present invention provides a solid waste treatment system, comprising:

the pretreatment unit is used for pretreating solid waste to obtain a solid waste gasification raw material with a heat value of more than or equal to 3000kJ/kg and a water content of less than or equal to 40%;

the fixed bed slag gasification furnace is provided with a gasification chamber and a synthesis gas outlet communicated with the gasification chamber, and is used for gasifying solid waste gasification raw materials to generate crude synthesis gas;

the coal water slurry gasification furnace is provided with a combustion chamber, a top burner communicated with the combustion chamber and more than one side inlet, at least one side inlet is communicated with a synthetic gas outlet of the fixed bed slag gasification furnace, and the coal water slurry gasification furnace is used for pressurizing and gasifying the crude synthetic gas and the coal water slurry in the presence of oxygen to obtain the synthetic gas.

In the solid waste treatment method and the system, the pretreated solid waste is pressurized and gasified in the fixed bed slag gasification furnace to generate the crude synthesis gas, and the crude synthesis gas is secondarily gasified in the water-coal-slurry gasification furnace, so that a high-quality synthesis gas product can be obtained, and the harmless and recycling treatment of the solid waste is realized. Effective gas (CO + H) in syngas ₂ ) High content of (a), and low content of organic impurities and acidic impurities.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a flow chart of a solid waste treatment system according to an embodiment of the present invention.

Fig. 2 is a schematic top view of a coal water slurry gasification furnace in a solid waste treatment system according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, features of various aspects of the present invention and exemplary embodiments will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. In the drawings and the following description, at least some well-known structures and techniques have not been shown in detail in order to avoid unnecessarily obscuring the present invention; also, the dimensions of some of the structures may be exaggerated for clarity. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In the description of the present invention, it is to be noted that, unless otherwise specified, "above" and "below" are inclusive of the present numbers; the meaning of "a plurality of" and "several" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated for convenience in describing the invention and to simplify description, but do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The directional terms appearing in the following description are intended to be illustrative in all directions, and are not intended to limit the specific construction of embodiments of the present invention. In the description of the present invention, it should also be noted that, unless otherwise explicitly stated or limited, the terms "mounted" and "connected" are to be construed broadly, e.g., as being fixed or detachable or integrally connected; can be directly connected or indirectly connected. The specific meaning of the above terms in the present invention can be understood as appropriate to those of ordinary skill in the art.

The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description more particularly exemplifies illustrative embodiments. At various points throughout this application, guidance is provided through a list of embodiments that can be used in various combinations. In each instance, the list is merely a representative group and should not be construed as exhaustive.

First, a solid waste treatment method provided by the present invention is explained. The method comprises a pretreatment step, a fixed bed gasification step and a coal water slurry gasification step.

The pretreatment step comprises the step of pretreating the solid waste to obtain the solid waste gasification raw material with the heat value more than or equal to 3000kJ/kg and the water content less than or equal to 40 percent. The solid waste gasification raw material can meet the requirements of gasification process indexes of a fixed bed slag gasification furnace.

The present invention is not particularly limited to solid wastes. By way of example, the solid waste may be household waste, waste biomass, carbonaceous hazardous waste (e.g., medical waste), sludge solid waste, and the like.

In some embodiments, if the solid waste contains non-carbon-containing solid waste such as metal, slag, glass, etc., the pretreatment may include a step of screening the solid waste to obtain carbon-containing solid waste. Through screening treatment, the solid waste without carbon can be removed, and carbon-containing solid waste with higher heat value is obtained. The sieving treatment may be performed using a device known in the art, such as a sieving machine.

In some embodiments, the solid waste gasification feedstock may satisfy a calorific value of greater than or equal to 3000kJ/kg, greater than or equal to 5000kJ/kg, greater than or equal to 6000kJ/kg, greater than or equal to 8000kJ/kg, greater than or equal to 10000kJ/kg, greater than or equal to 12000kJ/kg, greater than or equal to 15000kJ/kg, or greater than or equal to 20000kJ/kg, and the like.

In some embodiments, the water content of the solid waste gasification feedstock is less than or equal to 40%, less than or equal to 30%, or less than or equal to 20%. If the solid waste contains more water, the pretreatment can comprise a step of dehydrating the solid waste so as to enable the water content of the solid waste gasification raw material to meet the requirement. The dehydration treatment may be carried out using equipment known in the art, such as a centrifuge.

In some embodiments, it is preferred that the solid waste gasification feedstock have a particle size of from 6mm to 50mm, for example from 10mm to 50mm, or from 20mm to 40 mm. If the volume of the solid waste is large, the pretreatment may include a step of crushing the solid waste to moderate the particle size thereof. The crushing treatment may be performed using an apparatus known in the art, such as a crusher.

In some embodiments, the pretreated solid waste may be mixed with semi-coke to form a solid waste gasification feedstock having a heating value of greater than or equal to 3000 kJ/kg. Preferably, the particle size of the semi-coke is from 6mm to 50mm, for example from 10mm to 50mm, or from 20mm to 40 mm.

As a specific example, the preprocessing step may include: screening the solid waste to obtain carbon-containing solid waste; crushing the carbon-containing solid waste to obtain solid waste with the particle size of 6-50 mm; and (3) dehydrating the solid waste to obtain the solid waste with the water content less than or equal to 40%. In some examples, the solid waste material has a calorific value of more than or equal to 3000kJ/kg and a water content of less than or equal to 40 percent and can be directly used as a solid waste gasification raw material. In other examples, the preprocessing step may further include: and mixing the solid waste with semi coke to form a solid waste gasification raw material.

In some embodiments, the solid waste has a particle size < 6mm after pretreatment. Such as sludge solid waste, etc. The solid waste particles are small in size, so that the solid waste particles have fluidity or semi-fluidity. In order to achieve a good gasification effect of the solid waste, the solid waste can be mixed with semi coke, and the particle size of the semi coke is 6mm to 50mm, for example 10mm to 50mm, or 20mm to 40 mm. The semi coke can make the obtained solid waste gasification raw material in a form of difficult flowing, and is beneficial to the subsequent fixed bed gasification step. The semi-coke of the mixture is a porous material, and the semi-coke with proper grain diameter can play a role of a framework, so that the air permeability of the solid waste gasification bed layer can be improved, and higher gasification efficiency is favorably obtained.

As a specific example, the preprocessing step may include: dehydrating the solid waste to obtain solid waste with the water content less than or equal to 40%; mixing the solid waste with semi coke with the grain diameter of 6-50 mm to form the solid waste gasification raw material. The mixing proportion of the semi-coke can be adjusted according to the heat value and the fluidity of the solid waste. Optionally, the mass ratio of the solid waste to the semi coke is 10: 90-90: 10, for example, 30: 70-70: 30, or 40: 60-60: 40.

The fixed bed gasification step is carried out in a fixed bed slag gasifier. The fixed bed gasification step comprises the step of carrying out pressure gasification on solid waste gasification raw materials in a fixed bed slag gasification furnace by using oxygen-containing gas and water vapor as gasification agents to generate crude synthesis gas.

The fixed bed slag gasifier may be of a construction known in the art. Generally, a fixed bed slag gasifier has a gasification chamber and is provided with a feed inlet at the top of the furnace, a slag discharge at the bottom of the furnace, and a syngas outlet at the side wall of the furnace. The gasification chamber can comprise a drying zone, a dry distillation zone, a gasification zone, a combustion zone and a slag zone from a feeding hole to a slag discharge hole. The gas outlet may be located between the drying zone and the feed inlet. Usually, more than 1 (e.g., 4 to 6) gasifying agent nozzles are distributed along the circumferential direction of the portion of the side wall of the furnace body corresponding to the combustion zone.

In the fixed bed slag gasification furnace, solid waste gasification raw materials are added from a feed inlet at the top of the furnace, and are downwards subjected to five areas of a drying area, a dry distillation area, a gasification area, a combustion area and a slag area in sequence, and then the ash left after the reaction is discharged from a slag discharge outlet at the bottom of the furnace in the form of slag. The gasifying agent is added into the combustion zone from a gasifying agent nozzle to participate in the gasification reaction. The gas in the furnace moves from bottom to top, and the sensible heat can be fully utilized. Finally generate CO and H ₂ Predominantly, and containing a certain quantity of, for example, CH ₄ 、C _n H _m Organic impurities such as oils and the like and e.g. H ₂ S, HCl, and the like, is sent out from the syngas outlet. In addition, the slag is chilled and then is crushed into glass-state slag, and heavy metals in solid wastes enter the glass slag to be solidified, so that the influence on the environment is greatly reduced.

In some embodiments, the temperature of the combustion zone is > 1400 ℃, the temperature of the gasification zone is in the range of 800 ℃ to 1400 ℃, and the temperature of the retort zone is in the range of 300 ℃ to 800 ℃. Because the fixed bed slag gasifier is in a high-temperature environment and is in a reducing atmosphere, the generation of dioxin is inhibited in the gasification process. And the gasification zone has higher temperature, which is beneficial to improving the effective gas content in the crude synthesis gas.

In some embodiments, the fixed bed gasification step is conducted at a pressure of 2.5MPa to 6.5MPa, such as 2.5MPa to 4MPa, 3.5MPa to 4.5MPa, or 3MPa to 5 MPa. The gasification pressure is proper, which is beneficial to improving the gasification efficiency and improving the effective gas content in the raw synthesis gas.

In some embodiments, the oxygen-containing gas is oxygen in a fixed bed gasification step. Preferably, the mass volume ratio of the water vapor to the oxygen in the gasifying agent can be 0.8kg/Nm ³ ～1.2kg/Nm ³ Or 0.9kg/Nm ³ ～1.1kg/Nm ³ . The mass to volume ratio of water vapor and oxygen refers to the mass of water vapor in kg to oxygen in Nm ³ Volume ratio in kg/Nm ³ 。Nm ³ Is a standard cubic meter which represents the amount of gas of 1 cubic meter at a pressure of one standard atmosphere (101.325kPa), a temperature of 0 c, and a relative humidity of 0%. The proportion of the water vapor and the oxygen in the gasifying agent is in a proper range, which is beneficial to improving the reaction temperature of a gasification zone, thereby improving the effective gas (CO + H) ₂ ) The gas production rate.

The step of gasifying the coal water slurry is carried out in a coal water slurry gasification furnace. The step of gasifying the coal water slurry comprises the step of pressurizing and gasifying the crude synthesis gas and the coal water slurry in a coal water slurry gasification furnace in the presence of oxygen to obtain synthesis gas.

The water-coal-slurry gasification furnace belongs to one kind of entrained flow bed gasification, and has the advantages of less impurities in the produced synthesis gas and the like. The coal water slurry gasification step may employ a coal water slurry gasification furnace known in the art. The raw syngas, along with the coal-water slurry and oxygen, may be injected into the furnace combustion chamber through a top burner or a side nozzle. In some embodiments, the coal water slurry and oxygen are injected into the combustion chamber through a top burner of the furnace body, and the raw synthesis gas from the fixed bed slag gasifier is fed into the combustion chamber through a side inlet of the furnace body. The side inlet may be located in a region of the furnace sidewall adjacent the furnace roof.

The coal water slurry can be prepared from coal powder and water. Optionally, the mass percentage concentration of the raw coal in the coal water slurry is 50-60%. The water for preparing the coal water slurry can also utilize industrial wastewater and saline wastewater. This is beneficial to alleviating the problem of enterprise wastewater treatment. In some embodiments, the water used to make the coal water slurry may be leachate generated during solid waste pretreatment and wastewater generated by subsequent systems. The gasification of coal water slurry has certain requirements on coal types. The raw material coal of the coal water slurry gasification furnace can be selected from coal types such as bituminous coal, lignite and the like. Anthracite coal may also be selected without regard to production costs.

Adding the crude synthesis gas, the coal water slurry and oxygen into a coal water slurry gasification furnace, and carrying out a series of chemical reactions under the pressurization condition to generate synthesis gas. The content of effective gas in the synthesis gas generated by the coal water slurry gasification furnace is high, such as CH ₄ 、C _n H _m Organic impurities such as oils and the like and e.g. H ₂ S, HCl, etc., and the synthesis gas composition is stable.

The bottom of the coal water slurry gasification furnace is provided with a slag water outlet, the coal water slurry gasification furnace is also internally provided with a chilling chamber positioned between the combustion chamber and the slag water outlet, and the combustion chamber is communicated with the chilling chamber through a slag hole. The synthetic gas carries the slag to flow downwards in a parallel flow mode, and is discharged from the side wall of the gasification furnace after being cooled by the chilling water in the chilling chamber. The slag is discharged from the bottom of the gasification furnace after quenching, so that the slag can be recycled.

The solid waste treatment method of the invention complements the advantages of the fixed bed slag gasification furnace and the coal water slurry gasification furnace, realizes the harmless and resource treatment of the solid waste, and can obtain high-quality synthesis gas products. Effective gas (CO + H) in syngas ₂ ) High content of (a), and low content of organic impurities and acid gas impurities. In addition, because the content of organic impurities in the synthesis gas is low, the subsequent wastewater treatment process can be simplified, and the problem of wastewater treatment is effectively relieved.

In some embodiments, the amount of oxygen added to the coal-water slurry gasification furnace satisfies the following conditions: the ratio of the mass of coal to the volume of oxygen in the coal water slurry is 0.7kg/Nm ³ ～0.8kg/Nm ³ . The amount of oxygen added into the coal water slurry gasification furnace is proper, which is beneficial to improving the gas production rate of effective gas and reducing the content of impurities such as organic matters, acid gas and the like.

In some embodiments, the mass to volume ratio of the coal-water slurry to the raw syngas is 0.8kg/Nm ³ ～0.9kg/Nm ³ . The ratio of the coal water slurry to the crude synthesis gas is proper, which is beneficial to improving the gas yield of the effective gas and reducing the content of impurities such as organic matters, acid gas and the like.

In some embodiments, in the step of gasifying the coal water slurry, the reaction temperature in the coal water slurry gasifier is 1200 ℃ to 1400 ℃.

In some embodiments, the pressure at which the pressure gasification is carried out in the coal water slurry gasification step is from 2MPa to 4MPa, such as from 2MPa to 3MPa, or from 2.5MPa to 3.5 MPa.

In some embodiments, the pressure of the pressurized gasification in the fixed bed gasification step is greater than the pressure of the pressurized gasification in the coal water slurry gasification step. Therefore, the crude synthesis gas generated by the fixed bed slag gasifier can flow to the water-coal-slurry gasifier conveniently, high-temperature gas in the water-coal-slurry gasifier can be prevented from flowing back to the fixed bed slag gasifier, the system is ensured to operate stably, and equipment is prevented from being damaged.

The invention next provides a solid waste treatment system. The system can implement the solid waste treatment method of the invention. Fig. 1 shows a solid waste treatment system as an example. Referring to fig. 1, the solid waste treatment system provided by the invention comprises a pretreatment unit 10, a fixed bed slag gasification furnace 20 and a coal water slurry gasification furnace 30.

The pretreatment unit 10 may include one or more of a sieving unit, a crushing unit, a dewatering unit, and a mixing unit.

And the screening unit is used for screening the solid wastes. The screening unit may employ screening equipment known in the art, such as a screener.

The crushing unit is used for crushing solid wastes. The crushing unit may employ crushing equipment known in the art, such as a crusher.

The dehydration unit is used for dehydrating the solid wastes. The dewatering unit may employ dewatering equipment known in the art, such as a centrifuge.

The mixing unit is used for mixing the solid waste with the semi coke. The mixing unit may employ mixing equipment known in the art, such as a stirred tank.

As an example, the pre-treatment unit 10 may comprise a sieving unit, a crushing unit, a dewatering unit and optionally a mixing unit. And the screening unit is used for screening the solid waste to obtain the carbon-containing solid waste. The crushing unit is used for crushing the carbon-containing solid waste to obtain solid waste with the particle size of 6-50 mm. The dehydration unit is used for dehydrating the solid waste to obtain the solid waste with the water content less than or equal to 40 percent. An optional mixing unit is used to mix the solid waste with the semi-coke as required.

As another example, the pretreatment unit 10 may include a dehydration unit and a mixing unit. The dehydration unit is used for dehydrating the solid waste to obtain the solid waste with the water content less than or equal to 40 percent. The mixing unit is used for mixing the solid waste with the semi coke.

The fixed bed slag gasifier 20 may be of a construction known in the art. The fixed bed slag gasifier 20 has a gasification chamber 21 and a syngas outlet 22 communicating with the gasification chamber 21. The fixed bed slag gasifier 20 is further provided with a feed inlet 23 positioned at the top of the furnace body, a slag discharge port 24 positioned at the bottom of the furnace body, and a gasifying agent nozzle 25 positioned on the side wall of the furnace body. The syngas outlet 22 is typically located in the side wall of the furnace and may be located between the drying zone and the feed inlet 23. The gasifying agent nozzles 25 are arranged corresponding to the combustion zone.

The water-coal-slurry gasification furnace 30 has a combustion chamber 31, a top burner 32 communicating with the combustion chamber 31, and one or more side inlets 33. At least one side inlet 33 communicates with the syngas outlet 22 of the fixed bed slag gasifier 20 to receive the raw syngas generated by the fixed bed slag gasifier 20. The side inlet 33 may be disposed at an upper half of the furnace body, for example, at a region corresponding to the combustion chamber 31 and near the top of the coal-water slurry gasification furnace 30.

Referring to fig. 2, in some embodiments, in the coal-water slurry gasification furnace 30, the side inlet 33 is disposed on the side wall of the coal-water slurry gasification furnace 30 in a tangential direction of the side wall, so that the raw synthesis gas enters the combustion chamber 31 substantially tangentially to the side wall. Therefore, a better flow field is formed in the coal water slurry gasification furnace 30, the gas production rate of effective gas is improved, and the content of impurities such as organic matters, acid gas and the like is reduced.

In some embodiments, the distance between the side inlet 33 and the connection position of the upper end enclosure 34 and the side wall of the coal-water slurry gasification furnace 30 is 500 mm-600 mm. Therefore, a better flow field is formed in the coal water slurry gasification furnace 30, the gas production rate of effective gas is improved, and the content of impurities such as organic matters, acid gas and the like is reduced. The side inlet 33 may be perpendicular to the central axis of the coal-water slurry gasification furnace 30. The distance between the side inlet 33 and the upper sealing head 34 is measured by the distance L between the central axis of the side inlet 33 and the connection part of the upper sealing head 34 and the side wall.

In some embodiments, a flow adjusting device 40 is disposed between the side inlet 33 of the coal-water slurry gasification furnace 30 and the syngas outlet 22 of the fixed-bed slag gasification furnace 20. The flow of the raw synthesis gas entering the coal-water slurry gasification furnace 30 is conveniently adjusted by the flow adjusting device 40.

In some embodiments, the bottom of the coal-water slurry gasification furnace 30 is provided with a slag water outlet 35, the coal-water slurry gasification furnace 30 is also internally provided with a chilling chamber 36 positioned between the combustion chamber 31 and the slag water outlet 35, and the combustion chamber 31 is communicated with the chilling chamber 36 through a slag hole 37. The synthetic gas outlet 38 of the coal-water slurry gasification furnace 30 is arranged on the side wall of the furnace body and is communicated with the chilling chamber 36, and is positioned at the area of the corresponding chilling chamber 36, which is close to the combustion chamber 31. The synthetic gas generated by the combustion chamber 31 enters the chilling chamber 36 through a slag hole 37 for chilling washing, and then is sent out through a synthetic gas outlet 38.

In some embodiments, the system further comprises a washing unit 50. The washing unit 50 is used for cooling and dedusting the synthesis gas sent out from the coal water slurry gasification furnace 30. Moreover, the scrubbing unit 50 may also scrub the syngas to further reduce the acid gas impurity content. As an example, the scrubbing unit 50 may include a venturi scrubber 51 connected to the syngas outlet 38 of the coal-water slurry gasification furnace 30, and a scrubbing tower 52 connected to a gas outlet of the venturi scrubber 51. The venturi scrubber 51 may remove dust and cool the syngas, and may also remove acid gases. Scrubber 52 may provide fine dust removal of the syngas with further cooling and further acid gas removal. The scrubber 52 may be a packed scrubber, a spray tower, or the like.

The scrubbing liquid of venturi scrubber 51 and scrubbing tower 52 can be selected as desired. By way of example, the scrubbing liquid of the venturi scrubber 51 and the scrubbing tower 52 may both be water.

Because the content of impurities such as organic matters and acid gases in the synthesis gas sent out by the coal water slurry gasification furnace 30 is low, the water quality of the washing water washed by the washing unit 50 is simple, the washing water can be recycled, and the wastewater discharge is greatly reduced. In some embodiments, the scrubbing unit 50 further comprises a solid-liquid separation device 53 and a circulation pump 54 connected between the scrubbing liquid outlet and the scrubbing liquid inlet of the scrubbing tower 52. The solid-liquid separation device 53 performs solid-liquid separation treatment on the washing liquid, and the obtained washing liquid is returned to the washing tower 52 by the circulation pump 54, thereby realizing recycling. The solid-liquid separation device 53 may be a settling tank.

In some embodiments, a wash liquor treatment device 55 may also be connected between the solid waste separation device 53 and the circulation pump 54. The scrubbing liquid treatment device 55 is used to remove acidic gases from the scrubbing liquid. The scrubbing liquid treatment apparatus 55 can be any apparatus known in the art capable of removing acid gases from scrubbing liquid. For example, the wash treatment device 55 can be a device, such as a stripper, that employs stripping techniques to strip off the acid gases in the wash.

In some embodiments, the washing liquid outlet of the washing tower 52 is connected to a chilled water inlet (not shown) of the coal-water slurry gasifier 30. At least a part of the bottom liquid of the washing tower 52 can be used as chilling water for the water-coal-slurry gasification furnace 30.

In some embodiments, the liquid outlet of the venturi scrubber 51 is connected to the chilled water inlet of the coal-water slurry gasifier 30. At least a part of the washing liquid of the venturi scrubber 51 may be used for the quenching water of the coal-water slurry gasification furnace 30.

In some embodiments, the wash water after washing by the washing unit 50 may also be used to make the coal water slurry.

Although not shown in the drawings, the solid waste treatment system of the present invention may further optionally include a conveying unit (e.g., including a conveying belt, a silo, etc.), a slag discharge unit, a gasifying agent supply unit, a jacket water circulation unit (the furnace body may be provided with a cooling water jacket), and the like. Each unit may include associated devices as known in the art.

The technical features described herein for the solid waste treatment method of the present invention can also be applied to the solid waste treatment system of the present invention.

The synthesis gas produced by the solid waste treatment method and the system can be used as chemical raw material gas, industrial gas, fuel gas and the like.

Examples

The following example employs a solid waste treatment system as shown in figure 1.

Example 1

The solid waste is domestic garbage. Screening the domestic garbage to screen out solid wastes such as metal, muck, glass and the like; crushing the household garbage into particles with the particle size of 6-50 mm; then the household garbage is dehydrated. And mixing the domestic garbage and the semi-coke with the particle size of 6-50 mm according to the mass ratio of 40:60 to form a solid waste gasification raw material with the heat value of 13000kJ/kg and the water content of 20%.

The solid waste gasification raw material is added into a fixed bed slag gasification furnace from a furnace top feed inlet of the furnace through a conveying system, and sequentially undergoes drying, dry distillation, gasification and combustion under the gasification pressure of 4.0MPa, and is mixed with a steam oxidant (the mass volume ratio of water vapor to oxygen is 0.9 kg/Nm) ³ ) A series of reactions are carried out to generate crude synthesis gas which is discharged from a synthesis gas outlet. The temperature of the combustion zone in the furnace is more than 1400 ℃, the temperature of the gasification zone is 800-1400 ℃, and the temperature of the dry distillation zone is 300-800 ℃. The raw syngas temperature is 300 deg.C to 400 deg.C and the composition is given in Table 1. The ash after reaction is discharged from the bottom of the gasification furnace in the form of slag and is crushed into glass-state slag after chilling, and heavy metals in solid waste enter the glass slag to be solidified, so that the influence on the environment is greatly reduced.

The water-coal-slurry gasification furnace is provided with a combustion chamber at the upper part and a chilling chamber at the lower part, and is also provided with a top burner communicated with the combustion chamber and a side inlet. The side inlet is arranged on the side wall along the tangential direction of the side wall of the coal water slurry gasification furnace and is 500mm away from the upper end enclosure of the coal water slurry gasification furnace. Mixing percolate generated by pretreating bituminous coal and domestic garbage with wastewater containing organic matters generated by washing synthetic gas, and preparing coal with high mass percentage concentrationCoal water slurry with the degree of 60%. And the coal water slurry and oxygen are sprayed into the coal water slurry gasification furnace from the top burner, and simultaneously, the crude synthesis gas from the fixed bed gasification furnace enters the coal water slurry gasification furnace from the side inlet after the flow of the crude synthesis gas is regulated by the flow regulating device. The oxygen amount added into the coal water slurry gasification furnace meets the requirement that the ratio of the mass of the coal in the coal water slurry to the volume of the oxygen is 0.75kg/Nm ³ . The mass volume ratio of the coal water slurry to the crude synthesis gas is 0.8kg/Nm ³ . Under the conditions that the gasification pressure is 3.9MPa and the gasification temperature is 1200 ℃, the crude synthesis gas, the coal water slurry and the oxygen are subjected to a series of reactions in the furnace to generate the synthesis gas. In the process, the raw synthesis gas undergoes secondary gasification, in which organic impurities and acid gases undergo a combustion reaction to be removed. In addition, organic matter in the wastewater is removed by a combustion reaction with oxygen. The content of effective gas in the obtained synthesis gas is more than 80 percent, the content of organic impurities is less than 0.5 percent, the content of acid gas impurities is less than 3 percent, and the quality of the synthesis gas is greatly improved.

The syngas was discharged from the syngas outlet with the slag entrained and down, after chilled water cooling, and the composition is given in table 1. The slag is discharged from a slag water outlet after quenching, and can be recycled.

The subsequent washing unit washes the synthesis gas, so that the content of acid gas can be further reduced. The quality of the generated washing water is simple, the main pollutant acid gas can be recycled or pulped after being stripped, and the discharge of waste water is greatly reduced.

Table 1 shows the composition of the raw synthesis gas discharged from the fixed-bed slag gasifier and the synthesis gas produced from the coal-water slurry gasifier in percentage by volume according to example 1.

TABLE 1

From the above results, it can be seen that the solid waste treatment method and system of the present invention can obtain high quality syngas products, and realize harmless and recycling treatment of solid waste. Effective gas (CO + H) in synthetic gas ₂ ) Of (1) containsHigh content, and low content of organic impurities and acidic impurities.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The solid waste treatment method is characterized by comprising the following steps:

(A) pretreating solid waste to obtain solid waste gasification raw material with a heat value of more than or equal to 3000kJ/kg and a water content of less than or equal to 40%;

(B) carrying out pressure gasification on the solid waste gasification raw material in a fixed bed slag gasification furnace by using oxygen-containing gas and steam as gasification agents to generate crude synthesis gas;

(C) and carrying out pressure gasification on the crude synthesis gas and the coal water slurry in the presence of oxygen in a coal water slurry gasification furnace to obtain synthesis gas.

2. The method of claim 1, wherein the pressure of the pressure gasification in step (B) is higher than the pressure of the pressure gasification in step (C).

3. The process according to claim 1 or 2, wherein the pressure of the pressure gasification in step (B) is 2.5MPa to 6.5 MPa; and/or the presence of a gas in the gas,

the pressure for the pressure gasification in the step (C) is 2MPa to 4 MPa.

4. The method of claim 1, wherein the oxygen-containing gas in step (B) is oxygen, and wherein the mass-to-volume ratio of water vapor to oxygen in the gasifying agent is 0.8kg/Nm ³ ～1.2kg/Nm ³ 。

5. The method according to claim 1, wherein the mass percentage concentration of the raw coal in the coal water slurry in the step (C) is 50-60%; and/or the presence of a gas in the atmosphere,

the ratio of the mass of the coal in the coal water slurry in the step (C) to the volume of the oxygen is 0.7kg/Nm ³ ～0.8kg/Nm ³ 。

6. The method according to claim 1 or 5, wherein in the step (C), the mass volume ratio of the coal water slurry to the raw synthesis gas is 0.8kg/Nm ³ ～0.9kg/Nm ³ 。

7. The method of claim 1, wherein the pre-processing of step (a) comprises:

screening the solid waste to obtain carbon-containing solid waste;

crushing the carbon-containing solid waste to obtain solid waste with the particle size of 6-50 mm;

dehydrating the solid waste to obtain solid waste with the water content less than or equal to 40%;

the solid waste is directly used as the solid waste gasification raw material, or the pretreatment further comprises: mixing the solid waste with semi coke with the particle size of 6-50 mm to form the solid waste gasification raw material;

alternatively, the pretreatment of step (a) comprises:

dehydrating the solid waste to obtain a solid waste material with the water content less than or equal to 40%, wherein the particle size of the solid waste material is less than 6 mm;

and mixing the solid waste with semi coke with the particle size of 6-50 mm to form the solid waste gasification raw material.

8. A solid waste treatment system, comprising:

the fixed bed slag gasification furnace is provided with a gasification chamber and a synthesis gas outlet communicated with the gasification chamber, and is used for gasifying the solid waste gasification raw material to generate crude synthesis gas;

the coal water slurry gasification furnace is provided with a combustion chamber, a top burner communicated with the combustion chamber and more than one side inlet, at least one side inlet is communicated with the synthetic gas outlet of the fixed bed slag gasification furnace, and the coal water slurry gasification furnace is used for pressurizing and gasifying the crude synthetic gas and the coal water slurry in the presence of oxygen to obtain the synthetic gas.

9. The system of claim 8, wherein the side inlet is disposed on a side wall of the coal-water slurry gasification furnace in a tangential direction of the side wall so that the raw syngas enters the combustion chamber substantially tangentially to the side wall.

10. The system of claim 8 or 9, wherein the distance between the side inlet and the joint of the upper head and the side wall of the coal-water slurry gasification furnace is 500-600 mm.

11. The system of claim 8, wherein a flow regulating device is arranged between the coal-water slurry gasification furnace and the fixed bed slag gasification furnace.

12. The system of claim 8, further comprising a washing unit, the washing unit comprising:

the Venturi scrubber is connected with a synthesis gas outlet of the coal water slurry gasification furnace;

a scrubber tower connected to the gas outlet of the venturi scrubber;

the solid-liquid separation equipment is connected with a washing liquid outlet of the washing tower;

and the washing liquid treatment equipment is connected with a liquid phase outlet of the solid-liquid separation equipment, and is connected to a washing liquid inlet of the washing tower through a circulating pump.

13. The system of claim 12, wherein a slag water outlet is arranged at the bottom of the coal water slurry gasification furnace, a chilling chamber is further arranged in the coal water slurry gasification furnace and is positioned between the combustion chamber and the slag water outlet, and the combustion chamber is communicated with the chilling chamber through a slag hole; and

a washing liquid outlet of the washing tower is connected with a chilling water inlet of the coal water slurry gasification furnace; and/or the liquid outlet of the Venturi scrubber is connected with the chilling water inlet of the coal water slurry gasification furnace.

14. The system of claim 8, wherein the pre-processing unit comprises at least one of:

the screening unit is used for screening the solid wastes;

the crushing unit is used for crushing the solid waste;

the dehydration unit is used for dehydrating the solid wastes;

and the mixing unit is used for mixing the solid waste with the semi coke.