CN114250092B - System and method for reducing emission of low-concentration combustible gas - Google Patents

System and method for reducing emission of low-concentration combustible gas Download PDF

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CN114250092B
CN114250092B CN202210030942.9A CN202210030942A CN114250092B CN 114250092 B CN114250092 B CN 114250092B CN 202210030942 A CN202210030942 A CN 202210030942A CN 114250092 B CN114250092 B CN 114250092B
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gas
fluidized bed
bed reactor
catalytic oxidation
catalyst
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CN114250092A (en
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由长福
王海名
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Tsinghua University
Shanxi Research Institute for Clean Energy of Tsinghua University
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Tsinghua University
Shanxi Research Institute for Clean Energy of Tsinghua University
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
    • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
    • C10L3/10—Working-up natural gas or synthetic natural gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/34—Purifying combustible gases containing carbon monoxide by catalytic conversion of impurities to more readily removable materials

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  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
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  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention relates to a system and a method for reducing emission of low-concentration combustible gas, comprising a gas heat exchange unit and a catalytic oxidation unit; the gas heat exchange unit comprises a gas heat exchanger, wherein the gas heat exchanger comprises a first gas channel for untreated gas to enter and pass through and a second gas channel for treated gas to pass through and be discharged; the catalytic oxidation unit comprises a fluidized bed reactor, wherein the fluidized bed reactor is used for carrying out catalytic oxidation reaction on the combustible gas; the outlet of the first gas channel is connected with the gas inlet of the catalytic oxidation unit, and the gas outlet of the catalytic oxidation unit is connected with the inlet of the second gas channel. The invention adopts the fluidization process to strengthen heat and mass transfer and gas-gas heat exchange to ensure the heat balance of the system and the catalytic oxidation means, thereby realizing the aim of reducing the emission of low-concentration combustible gas.

Description

System and method for reducing emission of low-concentration combustible gas
Technical Field
The invention belongs to the technical field of industrial process waste gas purification, and particularly relates to a system and a method for reducing emission of low-concentration combustible gas.
Background
Tail gases from many industrial processes contain low concentrations of combustible gases such as coal mine ventilation (less than 1% gas), lime kiln tail flue gas (less than 1% CO), coking industry tail gases (less than 0.1% VOC content), and the like. The direct discharge of these combustible gases brings about both waste of fuel resources and pollution of the environment.
A common method of industrially treating tail gas containing combustible gas is combustion, however, it is difficult to directly burn the tail gas containing low concentration combustible gas such as those listed above because of its low heat value. To achieve these low concentration combustible gas emissions reductions, common methods in industry include: high temperature treatment and medium and low temperature catalytic oxidation.
For example, patent document 1 discloses a process for purifying exhaust gas containing hydrogen sulfide and organic sulfur, in which the exhaust gas is preheated by a heat accumulator, then enters a catalytic oxidation reactor to perform oxidation reaction, and the high-temperature gas after the catalytic oxidation reaction passes through the heat accumulator.
Patent document 2 discloses a method for catalytic purification and heat utilization of low-calorific-value industrial tail gas, which aims at industrial tail gas with a total combustible component content of 5-15%, and carries out multistage catalytic oxidation on the industrial tail gas by using a multistage-structure catalytic reactor, so that the industrial tail gas can be directly discharged into the atmosphere, and meanwhile, the heat of the industrial tail gas is recycled by being sent into a waste heat boiler and sent back to a heat exchanger.
Citation literature:
patent document 1: CN112999843a;
patent document 2: CN107433127a.
Disclosure of Invention
Problems to be solved by the invention
The method of patent document 1 uses a heat accumulator for heat exchange, and its heat exchange capacity is limited by the capacity of the heat accumulator, so that it is difficult to use for the treatment of a large-volume gas, and the specific kind of the catalytic oxidation reactor bed thereof is not mentioned therein.
The method of patent document 2 is complicated and the total combustible component content in the aimed gas is still high, and the economy of treatment using the method is greatly reduced for a combustible gas of lower concentration.
Regarding the tail gas treatment method containing low-concentration combustible gas in the prior art, the method of high-temperature treatment requires a high-temperature environment, and is therefore limited by whether high-temperature equipment is arranged near an emission site or not; the medium-low temperature catalytic oxidation method mostly adopts a catalytic oxidation self-heating method to ensure that the temperature is at the reaction temperature of the catalyst, and mostly adopts a scheme of heat accumulation and cold air heating so as to reduce the influence of heat carried by smoke exhaust on the energy balance of the system, and in practical application, the problems of small single-machine treatment capacity, high catalyst cost and easy deactivation exist.
Therefore, there is a need to develop a system and method for reducing the emission of low concentration combustible gas with high air volume, high efficiency and low cost.
Solution for solving the problem
The invention provides a system and a method for reducing the emission of low-concentration combustible gas, which adopt the means of strengthening heat and mass transfer in the fluidization process, ensuring the heat balance of the system by gas-gas heat exchange and catalytic oxidation, thereby realizing the aim of reducing the emission of low-concentration combustible gas.
Specifically, the present invention solves the problems of the present invention by the following means.
[1] A system for abating low concentration combustible gases, characterized by: comprises a gas heat exchange unit and a catalytic oxidation unit;
the gas heat exchange unit comprises a gas heat exchanger, wherein the gas heat exchanger comprises a first gas channel for untreated gas to enter and pass through and a second gas channel for treated gas to pass through and be discharged;
the catalytic oxidation unit comprises a fluidized bed reactor, wherein the fluidized bed reactor is used for carrying out catalytic oxidation reaction on the combustible gas;
the outlet of the first gas channel is connected with the gas inlet of the catalytic oxidation unit, and the gas outlet of the catalytic oxidation unit is connected with the inlet of the second gas channel.
[2] The system of item [1], wherein the catalytic oxidation unit further comprises a catalyst feeder and a discharger connected to the fluidized bed reactor.
[3] The system of [1] or [2], wherein the catalytic oxidation unit further comprises a fuel feeder connected to a fluidized bed reactor, and wherein the fluidized bed reactor has a heat exchange device inside.
[4] The system according to [1] or [2], wherein the fluidized bed reactor is externally provided with insulation means or is composed of a refractory insulation material, preferably the fluidized bed reactor is provided with a metal lining and an outer layer composed of insulation material.
[5] The system according to [1] or [2], wherein a gas-solid separation device is further provided between the gas outlet of the catalytic oxidation unit and the inlet of the second gas passage, a feed port of the gas-solid separation device is connected with the gas outlet of the catalytic oxidation unit, the gas outlet of the gas-solid separation device is connected with the inlet of the second gas passage, and a solid outlet of the gas-solid separation device is connected with the fluidized bed reactor.
[6] The system according to [1] or [2], wherein the gas heat exchanger is a tubular heat exchanger or a rotary heat exchanger, and the fluidized bed reactor is a bubbling bed or a circulating fluidized bed.
[7] The system according to [1] or [2], wherein the gas introduction rate is 200,000Nm3/h or more and the system resistance is 7000Pa or less.
[8] A method for reducing the emission of low-concentration combustible gas, comprising the steps of:
the untreated gas containing the combustible gas is sent into a gas heat exchange unit for heating, so as to obtain the gas after temperature rise;
feeding the heated gas into a fluidized bed reactor, so that the combustible gas in the gas is oxidized in the presence of a catalyst and is converted into treated hot gas; and
the treated hot gas is sent into a gas heat exchange unit and is discharged after heat exchange;
wherein the content of the combustible gas in the untreated gas is 3% or less.
[9] The method according to [8], wherein the combustible gas is one or more selected from methane, carbon monoxide, hydrogen and other combustible volatile organic compounds; the catalyst is granular and contains one or more selected from iron, manganese, copper, cobalt, nickel, cerium and zirconium.
[10] The method of [8], further comprising one or more of the following steps:
adding catalyst to the fluidized bed reactor and withdrawing deactivated catalyst from the fluidized bed reactor;
adding fuel into the fluidized bed reactor; and
heat is removed from the fluidized bed reactor.
ADVANTAGEOUS EFFECTS OF INVENTION
The invention has the following advantages and beneficial effects:
(1) compared with the honeycomb or stacked particle catalysis method, the method strengthens gas particle mass transfer and reaction by adopting the fluidization method, has the advantages of low resistance and high efficiency, is suitable for treating large-air-volume gas, and in the fluidization reactor, particles frequently collide and rub, so that dust deposition in the treated gas can be effectively avoided, and the problem of carbon deposition on the surface of the catalyst can be alleviated.
(2) Through setting up the gas heat exchanger, can realize the maximum utilization of heat in the system when realizing the gaseous heating purpose of handling, reduce the energy consumption of system operation, practice thrift the cost.
(3) By arranging the catalyst feeder and the discharger, catalyst particles in the reactor can be added or discharged at any time during operation, so that the system is suitable for low-cost catalyst raw materials, even cheap and easily-obtained waste, and the operation cost of the system is reduced.
(4) The heat exchanger is arranged in the reactor, so that the control of the catalytic reaction temperature can be realized, and the heat insulation link of the reactor ensures the heat balance of the fluidized bed reactor.
Drawings
FIG. 1 is a schematic diagram of one embodiment of the system of the present invention.
Description of the reference numerals
1-a gas heat exchanger; 2-a fluidized bed reactor; 3-catalyst feeder; 4-a fuel feeder; 5-discharger; 6-a heat exchanger; 7-a gas-solid separator.
Detailed Description
The following describes the present invention in detail. The following description of the technical features is based on the representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples.
< terms and definitions >
In the present specification, "emission reduction" means reducing the amount of the components described in the exhaust gas;
in the present specification, the term "low-concentration combustible gas" means that the content of the combustible gas is 3% or less.
In the present specification, the numerical range indicated by the term "numerical value a to numerical value B" means a range including the end point numerical value A, B.
In the present specification, a numerical range indicated by "above" or "below" is a numerical range including the present number.
In the present specification, the meaning of "can" includes both the meaning of performing a certain process and the meaning of not performing a certain process.
In this specification, the use of "optionally" or "optional" means that certain substances, components, steps of performing, conditions of applying, etc. may or may not be used.
In the present specification, unit names used are international standard unit names, and "%" used denote volume percent unless otherwise specified.
Reference in the specification to "a preferred embodiment," "an embodiment," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the elements may be combined in any suitable manner in the various embodiments.
< System >
One of the purposes of the invention is to provide a system for reducing the emission of low-concentration combustible gas, which comprises a gas heat exchange unit and a catalytic oxidation unit;
the gas heat exchange unit comprises a gas heat exchanger, wherein the gas heat exchanger comprises a first gas channel for untreated gas to enter and pass through and a second gas channel for treated gas to pass through and be discharged;
the catalytic oxidation unit comprises a fluidized bed reactor, wherein the fluidized bed reactor is used for carrying out catalytic oxidation on the combustible gas;
the outlet of the first gas channel is connected with the gas inlet of the catalytic oxidation unit, and the gas outlet of the catalytic oxidation unit is connected with the inlet of the second gas channel.
The individual components of the system of the present invention are described in detail below.
Gas heat exchange unit
In the system of the present invention, the gas heat exchange unit is configured to exchange heat between the untreated gas and the treated gas subjected to catalytic oxidation, thereby allowing the untreated gas to be heated while the treated gas subjected to catalytic oxidation is cooled.
The system of the present invention is designed by such a gas heat exchange unit so as to maximize the use of heat within the system. In addition, compared with the mode of using a heat accumulator in the prior art, the mode of directly carrying out heat exchange on two gases in the heat exchange unit can realize the treatment of the gas with large air quantity without being limited by the capacity of the heat accumulator.
The gas heat exchange unit comprises a gas heat exchanger, wherein the gas heat exchanger comprises a first gas channel and a second gas channel; the outlet of the first gas channel is connected with the gas inlet of the catalytic oxidation unit, and the gas outlet of the catalytic oxidation unit is connected with the inlet of the second gas channel. The first gas channel is used for allowing untreated gas to enter and pass through, the second gas channel is used for allowing treated gas to pass through and discharge, and heat is conducted from treated gas with higher temperature to untreated gas with lower temperature. The gases in the first and second gas channels may flow in parallel or in countercurrent for heat exchange.
In one embodiment, the gas heat exchanger is a tube heat exchanger or a rotary heat exchanger.
Catalytic oxidation unit
In the system of the invention, the catalytic oxidation unit is configured to oxidize the combustible gas in the untreated gas in the presence of the catalyst so as to achieve the aim of reducing the emission of the combustible gas.
In the system of the present invention, the catalytic oxidation unit comprises a fluidized bed reactor in which the treated gas is catalytically oxidized in contact with the catalyst particles. The invention adopts the fluidized bed reactor, so that on one hand, the mass transfer and reaction between the gas and the catalyst particles are enhanced, and the fluidized bed reactor has the advantages of low resistance and high efficiency, and can realize the treatment of large-air-volume gas, and on the other hand, the particles frequently collide and rub in the fluidized bed reactor, thereby effectively avoiding the deposition of dust in the treated gas, and alleviating the problem of carbon deposition on the surface of the catalyst.
The present invention is not particularly limited with respect to a specific fluidized bed reactor, and may be any fluidized bed reactor known in the art, such as a bubbling bed or a circulating fluidized bed, etc.
In one embodiment, the catalytic oxidation unit further comprises a catalyst feeder and a discharger connected to the fluidized bed reactor. The catalyst particles are added into the fluidized bed reactor through a catalyst feeder and recycled in the fluidized bed reactor, and the deactivated catalyst particles are discharged from the fluidized bed reactor through a discharger. In the embodiment, through the arrangement of the catalyst feeder and the discharger, catalyst particles in the reactor can be added or discharged at any time in operation, so that the system can be suitable for low-cost catalyst raw materials, even cheap and easily-obtained waste can be used as a catalyst, and the operation cost of the system is reduced.
As the waste which can be used as the catalyst in the system of the present invention, waste metals such as waste copper slag, steel slag, manganese slag and the like can be cited.
In one embodiment, the catalytic oxidation unit further comprises a fuel feeder connected to the fluidized bed reactor, and the fluidized bed reactor has a heat exchange device inside. When the temperature in the fluidized bed reactor is lower than the catalyst action temperature, replenishing fuel from a fuel feeder to ensure that the temperature in the reactor is suitable for catalytic oxidation of low-concentration combustible gas by the catalyst; when the temperature in the fluidized bed reactor is higher than the catalyst action temperature, the heat is discharged through a heat exchange device in the fluidized bed reactor. In this embodiment, the control of the catalytic reaction temperature can be further achieved by the arrangement of the fuel feeder and the heat exchange means.
In one embodiment, the fluidized bed reactor is externally provided with insulation or is constructed of a refractory insulation material. For example, a fluidized bed reactor may have a metal inner liner and an outer layer composed of a thermal insulation material. The heat balance in the fluidized bed reactor is facilitated by carrying out heat insulation and heat preservation on the fluidized bed reactor, and the input of external heat is reduced or avoided, so that the running cost of the system is reduced as much as possible.
The invention is not particularly limited to a particular insulation material, and may be any insulation material known in the art to be suitable for use in a reactor, including, but not limited to, ceramics, mineral wool (e.g., glass wool), and polymeric foam materials, among others.
In one embodiment, a gas-solid separation device is further arranged between the gas outlet of the catalytic oxidation unit and the inlet of the second gas channel, the feed inlet of the gas-solid separation device is connected with the gas outlet of the catalytic oxidation unit, the gas outlet of the gas-solid separation device is connected with the inlet of the second gas channel, and the solid outlet of the gas-solid separation device is connected with the fluidized bed reactor. The gas-solid separation device is arranged to separate catalyst particles entrained in the gas exiting the catalytic oxidation unit and to return the separated catalyst particles to the catalytic oxidation unit. The design can avoid catalyst loss on one hand and prevent solid particles from being entrained in the treated gas and discharged together as particle pollutants on the other hand.
The system of the invention is suitable for treating large-air-volume gas, and the gas inlet speed is 200,000Nm 3 Preferably above/h, 300,000Nm 3 Preferably at least/h, more preferably 400,000Nm 3 And/or more.
The system of the present invention has a small system resistance, and the system resistance is 7000Pa or less, preferably 6000Pa or less. Wherein "system resistance" refers to the pressure differential of the process gas flowing through the reaction system.
The system of the present invention is further described below in conjunction with the accompanying drawings.
As shown in fig. 1, the system of the present invention comprises a gas heat exchanger 1, a fluidized bed reactor 2, a catalyst feeder 3, a fuel feeder 4, a discharger 5, a heat exchanger 6 and a gas-solid separator 7, wherein an outlet of a first gas passage of the gas heat exchanger 1 is connected with a gas inlet of the fluidized bed reactor 2, a gas outlet of the fluidized bed reactor 2 is connected with an inlet of the gas-solid separator 7, a gas outlet of the gas-solid separator 7 is connected with an inlet of a second passage of the gas heat exchanger 1, a solid outlet of the gas-solid separator 7 is connected with the fluidized bed reactor 2, the catalyst feeder 3, the fuel feeder 4 and the discharger 5 are connected with the fluidized bed reactor 2, and the heat exchanger 6 is located inside the fluidized bed reactor 2.
< method >
One of the purposes of the invention is to provide a method for reducing emission of low-concentration combustible gas, which comprises the following steps:
the untreated gas containing the combustible gas is sent into a gas heat exchange unit for heating, so as to obtain the gas after temperature rise;
feeding the heated gas into a fluidized bed reactor, so that the combustible gas in the gas is oxidized in the presence of a catalyst and is converted into treated hot gas;
the treated hot gas is sent into a gas heat exchange unit and is discharged after heat exchange;
optionally adding catalyst to the fluidized bed reactor and withdrawing deactivated catalyst from the fluidized bed reactor;
optionally adding fuel to the fluidized bed reactor; and
optionally removing heat from the fluidized bed reactor;
wherein the content of the combustible gas in the untreated gas is 3% or less.
In the method, the untreated gas and the treated hot gas are subjected to heat exchange, so that the aim of fully utilizing the reaction heat is fulfilled, the input of external heat is reduced as much as possible, and the energy consumption and the cost are reduced. By using the fluidized bed reactor for catalytic oxidation, the gas and the catalyst particles can be fully contacted, the oxidation rate of the combustible gas is improved, and the emission of the combustible gas is reduced as much as possible.
In one embodiment, the process of the invention can be carried out with the system of the invention described above, in which embodiment the preferred embodiments and the corresponding effects described for the system of the invention also apply to the process of the invention.
In one embodiment, the process of the present invention comprises the steps of adding catalyst to a fluidized bed reactor and withdrawing deactivated catalyst from the fluidized bed reactor. By this step, the catalyst in the fluidized bed reactor can be updated as needed, thereby ensuring the catalytic efficiency.
In one embodiment, the method of the present invention comprises the step of adding fuel to the fluidized bed reactor. When the temperature in the fluidized bed reactor is too low, the temperature can be maintained within the range of the catalyst action temperature by adding fuel into the fluidized bed reactor, so that the catalytic oxidation efficiency is ensured.
In the present specification, the "catalyst action temperature" refers to a temperature at which the catalyst can exert a catalytic action. The catalyst operating temperatures may vary from catalyst system to catalyst system or from combustible gas component to combustible gas component, for example, the catalyst operating temperatures of the various catalysts listed herein may range from 80 to 400 ℃ for treating carbon monoxide-containing gas and from 300 to 800 ℃ for treating methane-containing gas.
In one embodiment, the process of the present invention comprises the step of removing heat from the fluidized bed reactor, in which embodiment the removed heat is optionally transferred to a gas heat exchanger. By removing heat when the temperature of the fluidized bed reactor is too high, catalyst carbon deposition and high temperature deactivation are avoided.
In the present invention, the temperature in the fluidized bed reactor may be specifically selected according to the catalyst used and the gas to be treated. In one embodiment, the untreated gas is a gas containing low concentration methane, and the temperature in the fluidized bed reactor (the temperature of the gas in the fluidized bed reactor) is controlled to 300 to 580 ℃, for example, 350 to 550 ℃, or 400 to 500 ℃ using the waste copper slag as a catalyst.
In one embodiment, the combustible gas is one or more selected from methane, carbon monoxide, hydrogen and other combustible volatile organics. The content of the combustible gas in the untreated gas is 3% or less, preferably 2% or less, and more preferably 1% or less. The other components in the treated gas are non-combustible gases, such as one or more of inert gases, carbon dioxide, oxygen, nitrogen oxides, sulfur oxides, and the like, in addition to the combustible gas.
In one embodiment, the catalyst is in the form of particles and contains one or more selected from the group consisting of iron, manganese, copper, cobalt, nickel, cerium, and zirconium. The catalyst may be waste, such as waste copper slag, steel slag, manganese slag, etc., in view of cost reduction.
In the method of the invention, the oxidation rate of the combustible gas is more than 80 percent, even more than 90 percent, and the content of the combustible gas in the treated gas reaches the standard of direct discharge.
The process of the present invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, untreated gas is sent into a gas heat exchanger 1 to exchange heat with treated hot gas to form heated gas; the heated gas is sent into a fluidized bed reactor 2 for catalytic oxidation, materials discharged from the fluidized bed reactor 2 are subjected to gas-solid separation by a gas-solid separator 7, the obtained treated hot gas is sent into a gas heat exchanger 1, and solids separated by the gas-solid separator 7 are sent into the fluidized bed reactor 2 for continuous use; the catalyst is fed into the fluidized bed reactor 2 through the catalyst feeder 3, and the deactivated catalyst is discharged through the discharger 5; replenishing fuel from the fuel charger 4 when the temperature in the fluidized bed reactor 2 is below the lower limit of the catalyst operating temperature; when the temperature in the fluidized-bed reactor 2 is higher than the upper limit of the catalyst operating temperature, heat is discharged through the heat exchanger 6 in the fluidized-bed reactor.
The invention accordingly relates to the use of the system according to the invention or the method according to the invention for reducing the emission of combustible gases, such as for example for the treatment of coal mine ventilation, lime kiln tail gas, coking industry exhaust gases and the like.
The invention is further illustrated by the following examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications of the invention will become apparent to those skilled in the art upon reading the description herein, and such equivalents are intended to fall within the scope of the invention as defined by the appended claims.
Example 1
The untreated gas was ventilated for the coal mine with a throughput of 430,000Nm 3 And/h, wherein the concentration of methane is 0.8%, and a circulating fluidized bed reactor is adopted, and the catalyst material is waste copper slag. The gas heat exchanger adopts a rotary heat exchanger. The untreated gas with the temperature of 25 ℃ is sent into a gas heat exchanger to exchange heat with the treated hot gas with the temperature of 450 ℃ to form heated gas, and the temperature is about 410 ℃. And (5) feeding the heated gas into a circulating fluidized bed reactor. Catalyst particles are added through a catalyst feeder and recycled within the reactor, and spent catalyst particles are discharged from the discharge system. The low-concentration methane in the heated gas is oxidized and emits heat under the catalysis of the catalyst particles, and the heated gas is converted into the treated hot gas. When the temperature in the reactor is 600 ℃, the temperature is higher than the catalyst action temperature, so heat is discharged through a heat exchanger in the reactor, and the temperature of the hot gas after treatment is reduced to 450 ℃. The treated hot gas enters a gas heat exchanger to exchange heat with untreated gas, and then is discharged out of the whole system. The oxidation rate of methane reaches 90 percent, and the resistance of the whole system is 5500Pa.
The above description is only an example of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention
Industrial applicability
The system and method of the present invention may be used to reduce emissions of combustible gases, such as in the treatment of coal mine ventilation.

Claims (6)

1. A method for reducing the emission of a low-concentration combustible gas, which is characterized by using a system for reducing the emission of the low-concentration combustible gas, wherein the system for reducing the emission of the low-concentration combustible gas comprises a gas heat exchange unit and a catalytic oxidation unit;
the gas heat exchange unit comprises a gas heat exchanger, wherein the gas heat exchanger comprises a first gas channel for untreated gas to enter and pass through and a second gas channel for treated gas to pass through and be discharged;
the catalytic oxidation unit comprises a fluidized bed reactor, wherein the fluidized bed reactor is used for carrying out catalytic oxidation reaction on the combustible gas;
the outlet of the first gas channel is connected with the gas inlet of the catalytic oxidation unit, and the gas outlet of the catalytic oxidation unit is connected with the inlet of the second gas channel;
the catalytic oxidation unit further comprises a fuel feeder connected with the fluidized bed reactor, and a heat exchange device is arranged inside the fluidized bed reactor;
the fluidized bed reactor is provided with a metal lining and an outer layer which is made of a heat insulation material and is used for carrying out heat insulation and heat preservation on the fluidized bed reactor;
the method comprises the following steps:
the untreated gas containing the combustible gas is sent into the gas heat exchange unit to be heated, so that the heated gas is obtained;
feeding the heated gas into the fluidized bed reactor, so that the combustible gas in the gas is oxidized in the presence of a catalyst and is converted into treated hot gas; and
the treated hot gas is sent into the gas heat exchange unit and is discharged after heat exchange;
wherein the content of the combustible gas in the untreated gas is 3% by volume or less; the combustible gas contains one or two selected from methane and carbon monoxide;
the catalyst is one or more selected from waste copper slag, steel slag and manganese slag.
2. The method of claim 1, wherein the catalytic oxidation unit further comprises a catalyst feeder and a discharger connected to the fluidized bed reactor.
3. The method according to claim 1 or 2, characterized in that a gas-solid separation device is further arranged between the gas outlet of the catalytic oxidation unit and the inlet of the second gas channel, the feed opening of the gas-solid separation device being connected to the gas outlet of the catalytic oxidation unit, the gas outlet of the gas-solid separation device being connected to the inlet of the second gas channel, the solid outlet of the gas-solid separation device being connected to the fluidized bed reactor.
4. The method according to claim 1 or 2, wherein the gas heat exchanger is a tubular heat exchanger or a rotary heat exchanger, and the fluidized bed reactor is a bubbling bed or a circulating fluidized bed.
5. The method according to claim 1 or 2, wherein the gas inlet rate is 200,000nm 3 And/h or more, and a system resistance of 7000Pa or less, wherein the system resistance refers to a pressure difference of gas flowing through the system for reducing emission of the low-concentration combustible gas.
6. The method according to claim 1 or 2, further comprising one or more of the following steps:
adding catalyst to the fluidized bed reactor and withdrawing deactivated catalyst from the fluidized bed reactor;
adding fuel into the fluidized bed reactor; and
heat is removed from the fluidized bed reactor.
CN202210030942.9A 2022-01-12 2022-01-12 System and method for reducing emission of low-concentration combustible gas Active CN114250092B (en)

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