CN111735071A - Circulating fluidized bed catalytic combustion system for treating organic waste gas - Google Patents

Circulating fluidized bed catalytic combustion system for treating organic waste gas Download PDF

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Publication number
CN111735071A
CN111735071A CN202010675788.1A CN202010675788A CN111735071A CN 111735071 A CN111735071 A CN 111735071A CN 202010675788 A CN202010675788 A CN 202010675788A CN 111735071 A CN111735071 A CN 111735071A
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China
Prior art keywords
riser
organic waste
waste gas
fluidized bed
catalytic combustion
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李爱军
柯希玮
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Jiangsu Nanfang Coating & Environment Protection Equipment Co ltd
Tsinghua University
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Jiangsu Nanfang Coating & Environment Protection Equipment Co ltd
Tsinghua University
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Priority to CN202010675788.1A priority Critical patent/CN111735071A/en
Publication of CN111735071A publication Critical patent/CN111735071A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
    • F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
    • F23G7/07—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases in which combustion takes place in the presence of catalytic material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
    • F23G5/10—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating electric
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/44—Details; Accessories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/44—Details; Accessories
    • F23G5/46—Recuperation of heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/50—Control or safety arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2201/00—Pretreatment
    • F23G2201/60—Separating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2202/00—Combustion
    • F23G2202/60—Combustion in a catalytic combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2203/00—Furnace arrangements
    • F23G2203/50—Fluidised bed furnace
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2204/00—Supplementary heating arrangements
    • F23G2204/20—Supplementary heating arrangements using electric energy
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2206/00—Waste heat recuperation
    • F23G2206/10—Waste heat recuperation reintroducing the heat in the same process, e.g. for predrying
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2209/00—Specific waste
    • F23G2209/14—Gaseous waste or fumes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2900/00—Special features of, or arrangements for incinerators
    • F23G2900/50213—Preheating processes other than drying or pyrolysis

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention discloses a circulating fluidized bed catalytic combustion system for treating organic waste gas, belonging to the field of environmental protection. The system comprises a circulating fluidized bed catalytic combustion furnace, a heat exchanger (18) and an electric heating part (9), wherein the circulating fluidized bed catalytic combustion furnace comprises a fluidizing air chamber (2), an air distribution plate (3) and a lifting pipe (8), the fluidizing air chamber (2) is connected with an organic waste gas main pipe (14) with a fluidizing fan (15) through a lifting pipe air inlet main pipe (1), upper discharge ports (803) of the lifting pipe (8) with the electric heating part (9) distributed on the periphery are connected with a feed port of a separator (10), a discharge port of the separator (10) is connected with a feed port of a dipleg (11), a discharge port of the dipleg (11) is connected with a lifting pipe return pipe (802), and an exhaust port of the separator (10) is connected with the heat exchanger (18) through a pipeline. The system has high removal rate and high heat utilization rate, and can continuously and stably run for a long time.

Description

Circulating fluidized bed catalytic combustion system for treating organic waste gas
Technical Field
The invention belongs to the field of organic waste gas treatment, and particularly relates to a circulating fluidized bed catalytic combustion system for treating organic waste gas.
Background
Volatile Organic Compounds (VOCs) are one of the important sources of atmospheric pollution, are of a wide variety, and are a great hazard to the environment and humans. The sources of the VOCs are very wide, and the VOCs are likely to be generated in the processes of manufacturing, printing, spraying, cleaning, transporting and the like of the tobacco industry, the printing industry, the automobile industry, the decoration industry, the pharmaceutical industry, the textile industry, the chemical industry and the like. At present, the generation and discharge of organic waste gas in production activities are difficult to avoid, so that the treatment technology of the pollutants is very important.
The organic waste gas treatment technology can be roughly divided into two types, one is a recovery technology, and the recovery technology mainly comprises an adsorption method, an absorption method, a condensation method, a membrane separation method and the like; the other is non-recovery elimination technology, which mainly comprises a regenerative thermal oxidation method (RTO, RCO), a catalytic oxidation method, a porous medium combustion method, a biodegradation method, a low-temperature plasma method, a photocatalysis method and the like. Wherein, the combustion method refers to oxidizing (or combusting) the gas components of VOCs into CO under certain conditions2And H2And O, realizing waste gas purification. Compared with other methods, the combustion method has the advantages of relatively simple principle, equipment and operation, no byproduct and secondary pollution, and wide application.
At present, the heat storage oxidation devices which are applied more mainly comprise two types: regenerative Thermal Oxidation (RTO) and Regenerative Catalytic Oxidation (RCO). Both the two systems mainly comprise a conversion valve, a regenerative chamber and a combustion chamber, wherein the regenerative chamber is mainly two chambers or multiple chambers. The regenerative oxidation method can realize self-supply thermal oxidation decomposition of VOCs, and has high heat utilization rate but also has a plurality of defects. For example, RTO set combustion temperatures are high, energy consumption is high, and NO is presentxSecondary pollution problems such as generation and the like; although the RCO device reduces the combustion temperature, the catalyst is arranged in a fixed bedThe gas-solid contact area is limited, the catalyst consumption is large, and the cost is high. In addition, both devices require moving parts (switching valves that are constantly switched), and when the incoming flow of exhaust gas is uneven, the concentration of VOCs in the heat storage chamber is also unevenly distributed, which affects the extraction efficiency and may cause heat accumulation to over-heat a certain point.
The fluidized bed technology belongs to a continuous operation process, has good heat and mass transfer characteristics in the bed, large gas-solid contact area and uniform bed temperature, is widely applied to the chemical industry and the energy industry, and is gradually introduced into the field of organic waste gas treatment in recent years. The invention patent CN105233625A discloses a double fluidized bed adsorption and desorption device and a method for continuously treating organic waste gas. The invention can realize continuous operation to treat high-concentration organic waste gas and prevent heat accumulation, but two sets of fluidized bed devices are needed, the system structure and operation are complex, and the post-treatment of the concentrated organic waste gas is still needed.
The utility model CN202973118U discloses a volatile organic gas's circulating fluidized bed burns burning furnace, its characterized in that adopts the hollow bobble of aluminium oxide as the bed material, burns volatile organic gas under 850~950 ℃. The utility model has the advantages of high combustion temperature, no heat recovery design and large energy consumption; the used fluidized bed material is 1-5 mm granular pellets, the bed material is thick, and the fluidization quality is lower compared with common Geldart A-type or B-type particles.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a circulating fluidized bed catalytic combustion system for treating organic waste gas, which is suitable for high-concentration and low-concentration organic waste gas, is simple to operate, has high heat utilization rate, and can realize long-term continuous and stable operation.
The invention aims to solve the problems by the following technical scheme:
a circulating fluidized bed catalytic combustion system for treating organic waste gas is characterized in that: the system comprises a circulating fluidized bed catalytic combustion furnace, a heat exchanger and an electric heating part, wherein the circulating fluidized bed catalytic combustion furnace comprises a fluidizing air chamber, an air distribution plate, a lifting pipe, a separator and a dipleg, a feed inlet of the fluidizing air chamber is connected with an organic waste gas main pipe with a fluidizing fan through a lifting pipe air inlet main pipe, upper discharge ports of the lifting pipe, on which the electric heating part is distributed, are connected with a feed inlet of the separator, a lower discharge port of the separator is connected with an upper end feed inlet of the dipleg, a lower discharge port of the dipleg is connected with a lifting pipe return pipe, and an upper exhaust port of the separator is connected with the heat exchanger through a pipeline so as to recover.
A hot gas inlet of the heat exchanger is connected with a top gas outlet of the separator through a pipeline, a hot gas outlet is connected with a tail gas flue, a cold gas inlet is communicated with an organic waste gas main pipe, and a cold gas outlet is communicated with a riser gas inlet main pipe; the purified hot tail gas leaving from the separator enters a heat exchanger to exchange heat with cold organic waste gas to be treated so as to recover the heat of the tail gas and preheat the organic waste gas to be treated, and the preheated organic waste gas to be treated is sent into a fluidized air chamber of a circulating fluidized bed catalytic combustion furnace and enters a riser through an air distribution plate.
A material returning valve is arranged at the lower end of the dipleg, one inlet of the material returning valve is connected with the lower end of the dipleg, the other inlet of the material returning valve is connected with a riser gas inlet main pipe through a gas inlet branch pipe with a material returning wind supercharging fan, and one outlet of the material returning valve is connected with a material returning opening of the riser through a riser material returning pipe; catalyst particles flowing out of the dipleg fall into the return valve, one path of gas which is separated from the riser gas inlet main pipe enters the return valve after being pressurized by the return air booster fan, so that the catalyst particles in the return valve are conveyed and returned into the riser through the riser return pipe, and the circulating flow rate of the catalyst particles in the circulating fluidized bed catalytic combustion furnace can be adjusted by adjusting the outlet return air quantity of the booster fan.
A high-pressure screw feeder is arranged at a feed inlet of the front wall of the lifting pipe and is arranged below the storage bin; catalyst particles in the riser are fed from a front wall feeding port of the riser through a high-pressure screw feeder by a bin.
The lifting pipe is provided with an upper pressure measuring point and a lower pressure measuring point, the lower pressure measuring point is arranged on the upper side of the air distribution plate, and the upper pressure measuring point is arranged at the top of the inner cavity of the lifting pipe; in the operation process, the bed pressure drop in the riser is obtained through the upper pressure measuring point and the lower pressure measuring point, and when the bed pressure drop is in a set range, the catalyst particle inventory in the riser is normal without replenishing catalyst particles; when the bed pressure drop is less than the lower limit of the set range, the catalyst particle inventory in the riser is insufficient, and the catalyst particles need to be supplemented, so that the bed pressure drop in the riser is restored to be within the set range.
The upside edge of air distribution plate is equipped with row material pipe, and when VOCs gas component concentration in the organic waste gas through monitoring separator export found organic waste gas desorption rate and reduced, the valve of opening row material pipe was in order to discharge the old catalyst that a part of catalytic activity reduces, then supplyes fresh catalyst granule in the elevator pipe.
The organic waste gas main pipe between the fluidization fan and the heat exchanger is provided with a desulfurizing tank and a prefilter, organic waste gas to be treated with high sulfur content and high dust is firstly subjected to organic sulfur and inorganic sulfur removal in the waste gas through the desulfurizing tank and then large-particle dust removal through the prefilter before the organic waste gas is sent into the fluidization air chamber.
And a dehumidifier is arranged on the organic waste gas main pipe between the desulfurization tank and the prefilter.
The catalyst particles in the riser are catalyst powder belonging to Geldart group a or group B particles and are in fast fluidization during operation.
And the inner walls of the riser and the separator are coated with anti-wear castable.
The air distribution plate is a microporous plate type or an air cap type; and the separator is a two-stage high-efficiency cyclone separator.
The whole loop of the circulating fluidized bed catalytic combustion furnace is insulated.
Compared with the prior art, the invention has the following advantages:
compared with the traditional fixed bed catalytic combustion furnace and RCO, the gas-solid contact area in the fluidized bed is greatly increased, namely the reaction surface area is more, less catalyst materials are consumed under the condition of the same treatment capacity, the concentration range of the treated waste gas is wider, the flow resistance is smaller, and the cost and the energy consumption are saved.
The system of the invention adopts powdery catalyst particles, so that the catalytic reaction rate of the fine particles is faster, the response to the change of the concentration of VOCs is quicker and the system control under variable working conditions is facilitated besides greatly increasing the catalytic specific surface area and improving the fluidization quality.
The system of the invention has high heat and mass transfer rate in the fluidized bed, and the concentration of VOCs gas is more uniform and the bed temperature is uniform compared with that of a fixed bed, thereby preventing heat accumulation and local overheating risks.
The system recycles the heat of the purified tail gas at the outlet of the separator, has high heat utilization rate and saves energy consumption.
The system adopted by the invention can be continuously operated for a long time, has no movable parts such as a conversion valve and the like, and has simple operation and high reliability.
The system of the invention dynamically monitors the catalyst storage in the riser by utilizing the pressure drop of the bed in the riser, and ensures the long-term stable operation of the system by matching with the feeding device and the deactivated catalyst discharging device.
Drawings
FIG. 1 is a schematic diagram of a circulating fluidized bed catalytic combustion system for treating organic waste gases in accordance with the present invention;
FIG. 2 is a schematic diagram of a second improved circulating fluidized bed catalytic combustion system for treating organic waste gas based on FIG. 1;
FIG. 3 is a schematic diagram of a third improved circulating fluidized bed catalytic combustion system for treating organic waste gas based on FIG. 2;
FIG. 4 is a schematic diagram of a fourth improved circulating fluidized bed catalytic combustion system for treating organic waste gas based on FIG. 3;
fig. 5 is a schematic diagram of a fifth improved circulating fluidized bed catalytic combustion system for treating organic waste gas based on fig. 4.
Wherein: 1-a riser gas inlet main pipe; 2-a fluidizing air chamber; 3, a wind distribution plate; 4-a discharge pipe; 501-lower pressure measuring point; 502 — upper pressure measurement point; 6, a storage bin; 7-high pressure screw feeder; 8, a riser; 801-front wall feed port; 802-riser return pipe; 803-upper discharge port; 9-an electrical heating means; 10-a separator; 11-dipleg; 12-pneumatic flow valve; 13-return air booster fan; 14-organic waste gas main pipe; 15-a fluidization fan; 16-a devulcanizer; 17-a pre-filter; 18-a heat exchanger; 181-hot gas inlet; 182 — hot gas outlet; 183 cold gas outlet; 184-cold gas inlet; 19-tail gas flue; 20-a draught fan.
Detailed Description
The invention is further described with reference to the following figures and examples.
As shown in fig. 1 to 5, a circulating fluidized bed catalytic combustion system for treating organic exhaust gas, the system comprising:
the circulating fluidized bed catalytic combustion furnace comprises a fluidized air chamber 2, an air distribution plate 3, a riser 8, a separator 10 and a dipleg 11, wherein a discharge port 803 at the upper part of the riser 8 is connected with a feed port of the separator 10, a discharge port at the lower part of the separator 10 is connected with a feed port at the upper end of the dipleg 11, a discharge port at the lower end of the dipleg 11 is connected with a return pipe 802 of the riser, and the circulating fluidized bed catalytic combustion furnace is subjected to full-loop heat preservation;
the heat recovery and heating device comprises a heat exchanger 18 and an electric heating part 9, wherein the heat exchanger 18 is a dividing wall type heat exchanger, a hot gas inlet 181 of the heat exchanger 18 is connected with a top gas outlet of the separator 10 through a pipeline, a hot gas outlet 182 is connected with a tail gas flue 19, a cold gas inlet 184 is communicated with the organic waste gas main pipe 14, and a cold gas outlet 183 is communicated with the riser gas inlet main pipe 1, so that purified hot tail gas leaving from the separator 10 enters the heat exchanger 18 to exchange heat with cold organic waste gas to be treated so as to recover the heat of the tail gas and preheat the organic waste gas to be treated, and the preheated organic waste gas to be treated is sent into a fluidized air chamber 2 of the circulating fluidized bed catalytic combustion furnace and enters a riser 8 through an air distribution plate 3; the electric heating part 9 is arranged around the riser tube 8;
the air supply system comprises a fluidization fan 15, an induced draft fan 20 and a plurality of air pipes, wherein the fluidization fan 15 is arranged on the organic waste gas main pipe 14, the air inlet of the induced draft fan 20 is connected with the tail gas flue 19, and the air outlet of the induced draft fan 20 is communicated with the plant exhaust main pipe or directly communicated with the atmosphere;
the material returning device comprises a material returning valve 12, a material returning air booster fan 13 and a corresponding connecting air pipe, wherein the material returning valve 21 is arranged between a discharge port at the lower end of the dipleg 11 and an inlet of a riser material returning pipe 802, a branch pipe is divided from an air inlet main pipe 1 of the riser and is connected with an air inlet of the material returning air booster fan 13, and an air outlet of the material returning air booster fan 13 is connected with an inlet of the material returning valve 12 through a pipeline;
the feeding device comprises a stock bin 6 and a high-pressure screw feeder 7, the high-pressure screw feeder 7 is arranged at the front wall feeding port 801 of the lifting pipe 8, the high-pressure screw feeder 7 is arranged below the stock bin 6, and catalyst particles in the lifting pipe 8 are fed from the front wall feeding port 801 of the lifting pipe through the high-pressure screw feeder 7 by the stock bin 6; a lower pressure measuring point 501 and an upper pressure measuring point 502 for detecting the bed pressure drop in the riser 8 are also arranged on the riser 8, the lower pressure measuring point 501 is arranged on the upper side of the grid plate 3, and the upper pressure measuring point 502 is arranged at the top of the inner cavity of the riser 8;
the pre-filtering device comprises a desulfurizing tank 16 and a pre-filter 17, or the desulfurizing tank 16, a dehumidifier and the pre-filter 17, organic sulfur and inorganic sulfur in the organic waste gas to be treated with high sulfur content and high dust are removed through the desulfurizing tank 16 before the organic waste gas is sent into the fluidizing air chamber 2, and then large particle dust is removed through the pre-filter 17, wherein the desulfurizing tank 16 and the pre-filter 17 are arranged on an organic waste gas main pipe 14 between a fluidizing fan 15 and a heat exchanger 18; when the moisture content in the organic waste gas to be treated is too high, a dehumidifier is arranged on the organic waste gas main pipe 14 between the desulfurizing tank 16 and the pre-filter 17;
the discharging device comprises a discharging pipe 4 arranged at the edge of the upper side of the air distribution plate 3.
Example one
A circulating fluidized bed catalytic combustion system for treating organic waste gas as shown in fig. 1, the system comprising:
the circulating fluidized bed catalytic combustion furnace comprises a fluidized air chamber 2, an air distribution plate 3, a riser 8, a separator 10 and a dipleg 11, wherein a discharge port 803 at the upper part of the riser 8 is connected with a feed port of the separator 10, a discharge port at the lower part of the separator 10 is connected with a feed port at the upper end of the dipleg 11, a discharge port at the lower end of the dipleg 11 is connected with a return pipe 802 of the riser, and the circulating fluidized bed catalytic combustion furnace is subjected to full-loop heat preservation;
the heat recovery and heating device comprises a heat exchanger 18 and an electric heating part 9, wherein the heat exchanger 18 is a dividing wall type heat exchanger, a hot gas inlet 181 of the heat exchanger 18 is connected with a top gas outlet of the separator 10 through a pipeline, a hot gas outlet 182 is connected with a tail gas flue 19, a cold gas inlet 184 is communicated with the organic waste gas main pipe 14, and a cold gas outlet 183 is communicated with the riser gas inlet main pipe 1, so that purified hot tail gas leaving from the separator 10 enters the heat exchanger 18 to exchange heat with cold organic waste gas to be treated so as to recover the heat of the tail gas and preheat the organic waste gas to be treated, and the preheated organic waste gas to be treated is sent into a fluidized air chamber 2 of the circulating fluidized bed catalytic combustion furnace and enters a riser 8 through an air distribution plate 3; the electric heating part 9 is arranged around the riser tube 8;
the air supply system comprises a fluidizing fan 15, an induced draft fan 20 and a plurality of air pipes, wherein the fluidizing fan 15 is arranged on the organic waste gas main pipe 14, the air inlet of the induced draft fan 20 is connected with the tail gas flue 19, and the air outlet of the induced draft fan 20 is communicated with the plant exhaust main pipe or directly communicated with the atmosphere.
In the first embodiment, the method for using the circulating fluidized bed catalytic combustion system comprises the following steps:
A. under the action of the electric heating component 9, the temperature of a riser pipe 8 in the circulating fluidized bed catalytic combustion furnace is controlled within a set catalytic combustion temperature range;
B. organic waste gas to be treated is sent into a fluidization air chamber 2 from a riser gas inlet main pipe 1 and then enters a riser 8 through an air distribution plate 3, so that catalyst particles in the riser 8 are fluidized rapidly and simultaneously catalyze VOCs components in the organic waste gas to be treated to be oxidized and decomposed, and the organic waste gas to be treated is purified;
C. the gas flow after oxidative decomposition carries partial catalyst particles to move to the upper part of the riser tube 8 and enter a separator 10, the catalyst particles are separated and return to the riser tube 8 through a dipleg 11, and the purified hot tail gas leaves the separator 10;
D. the purified hot tail gas leaving from the separator 10 enters a heat exchanger 18 to exchange heat with the cold organic waste gas to be treated so as to utilize the heat of the tail gas, and the tail gas after heat exchange is converged into a tail gas flue 19 and finally introduced into a plant exhaust main pipe or exhausted into the atmosphere; the preheated organic waste gas to be treated is sent into a fluidizing air chamber 2 of the circulating fluidized bed catalytic combustion furnace and enters a riser 8 through an air distribution plate 3.
The system of the invention adopts the catalyst to catalyze the volatile organic compounds to be oxidized and decomposed into CO2And H2And harmless gases such as O and the like reduce the activation energy of the reaction, so that the oxidation reaction can be carried out at a lower temperature than direct combustion, and the energy consumption is saved. The core of the system is that when gas flows upwards through a catalyst particle bed layer, particles are suspended in a fluidized state, so that the gas-solid phase interfacial area is greatly increased, namely the reaction surface area is increased, the catalytic reaction rate and the catalyst utilization rate are improved, and the cost is saved; meanwhile, the heat of the tail gas at the outlet of the combustion furnace is utilized to heat the organic waste gas to be treated, so that the heat utilization rate of the system is improved.
The system of the invention adopts a circulating fluidized bed, and in order to reduce the escaping loss of catalyst particles as much as possible, the system needs to ensure high gas-solid separation efficiency, and further, the separator 10 preferably adopts a two-stage high-efficiency cyclone separator.
In the system of the present invention, in order to make the air distribution as uniform as possible and prevent catalyst particles having a particle size of generally hundreds of micrometers from blocking the air flow channel on the air distribution plate, it is preferable that the air distribution plate 3 is a microporous plate type or a hood type.
In the system of the invention, the catalyst bed materials adopted are usually noble metal particles such as Pd, Pt and the like, non-noble metal particles such as Ce, Co, Cu and the like, or composite metal particles such as Mn-Ce, Cu-Co and the like, most of the catalyst materials are hard, and the catalyst materials are easy to wear or even perforate the inner walls of the riser 8 and the separator 10 in the long-term fluidization process, thereby influencing the service life of the equipment. According to the system of the invention, furthermore, the inner wall of the riser 8 and the inner wall of the separator 10 are coated with an anti-wear castable.
In the system of the present invention, the combustion temperature in the circulating fluidized bed catalytic combustor is determined by the composition of the gas to be treated and the kind of the catalyst, and there is an optimal temperature window for the oxidation reaction. To ensure that the organic waste gas is completely combusted to meet emission standards, the temperature in the riser 8 should be within the required range. According to the system of the invention, further, the temperature control inside the riser 8 is achieved by the coordinated cooperation of the heat exchanger 18 and the electric heating element 9, in particular: when the circulating fluidized bed catalytic combustion furnace starts to operate, the electric heating part 9 is turned on to heat the temperature of the riser pipe 8 to be within the set catalytic combustion temperature range; in the operation process, when the concentration of the organic waste gas entering the circulating fluidized bed catalytic combustion furnace is high, and the heat exchange heat and the oxidation reaction heat can maintain the temperature in the riser pipe 8 within the set catalytic combustion temperature range, the electric heating part 9 is closed; on the contrary, if the concentration of the organic waste gas entering the circulating fluidized bed catalytic combustion furnace is low, the heat exchange heat plus the oxidation reaction heat is not enough to make the temperature in the riser tube 8 reach the lower limit of the set catalytic combustion temperature range, the electric heating component 9 is started to control the temperature in the riser tube to be maintained in the set catalytic combustion temperature range.
In the system of the present invention, in order to form a bed layer with a relatively high concentration of catalyst particles in the tube and simultaneously form strong axial back-mixing of solids to increase the catalyst retention time under the condition of high air flow of organic waste gas, i.e. at a high operating gas velocity in the riser 8, further, the catalyst particles in the riser 8 are in a fast fluidization state during the operation.
In the system of the invention, in order to obtain larger specific surface area of catalyst particles, reduce wind resistance, ensure fast fluidization of particles in the riser 8 and ensure fluidization quality, the catalyst is further powdery particles belonging to Geldart A-type or B-type particles.
Example two
As shown in fig. 2, an improved circulating fluidized bed catalytic combustion system for treating organic waste gas is provided on the basis of the circulating fluidized bed catalytic combustion system for treating organic waste gas shown in fig. 1. In addition to the components of system one, system two also includes a material returning device, also called a particle circulation control device, which is not only used for adjusting and controlling the particle circulation to achieve the required particle circulation rate; while helping to prevent a "back-streaming" flow of gas from the riser 8 to the separator 10. The material returning device comprises a material returning valve 12, a material returning air booster fan 13 and a corresponding connecting air pipe, wherein the material returning valve 21 is arranged between a discharge port at the lower end of a dipleg 11 and an inlet of a riser material returning pipe 802, a branch pipe is branched from an air inlet main pipe 1 of a riser and is connected with an air inlet of the material returning air booster fan 13, and an air outlet of the material returning air booster fan 13 is connected with an inlet of the material returning valve 12 through a pipeline.
In the second embodiment, the use method based on the second system includes a material returning operation in addition to the steps described in the first embodiment, specifically: catalyst particles discharged from the separator 10 fall into the return valve 12, and one path of gas (return air) branched from the riser gas inlet main pipe 1 enters the return valve 12 after being pressurized by the return air booster fan 13 so as to convey the catalyst particles to return to the riser 8. The circulating flow rate of the catalyst particles in the circulating fluidized bed catalytic combustion furnace can be adjusted by adjusting the outlet return air volume of the booster fan 13.
To achieve a high circulation flow rate, the return valve 12 should have as little resistance as possible. In this embodiment, a pneumatic flow valve such as an L-type valve or a V-type valve is preferably used as the return valve 12.
EXAMPLE III
As shown in fig. 3, an improved circulating fluidized bed catalytic combustion system for treating organic waste gas is also provided on the basis of the circulating fluidized bed catalytic combustion system for treating organic waste gas shown in fig. 2. Besides the components in the second system, the third system further comprises a bin 6, a high-pressure screw feeder 7, a lower pressure measuring point 501 and an upper pressure measuring point 502, the high-pressure screw feeder 7 is arranged at a feeding port 801 of the front wall of the riser 8, the high-pressure screw feeder 7 is arranged below the bin 6, the lower pressure measuring point 501 is arranged on the upper side of the air distribution plate 3, and the upper pressure measuring point 502 is arranged at the top of the inner cavity of the riser 8.
In this embodiment, the use method based on the system three includes, in addition to the steps described in the system two, a material feeding and stock quantity adjusting operation, specifically: catalyst particles are stored in the bin 6, and before the system is started, sufficient catalyst particles are sent into the riser 8 through the high-pressure screw feeder 7; in the operation process, the bed pressure drop (hereinafter referred to as bed pressure drop) in the riser 8 is obtained through the lower pressure measuring point 501 and the upper pressure measuring point 502. The bed pressure drop is positively correlated with the particle stock (hereinafter referred to as bed stock) and the circulation quantity in the riser 8, when the bed pressure drop is in a set range, the bed stock is normal, and the high-pressure screw feeder 7 is not required to be started; when the bed pressure drop is smaller than the lower limit of the set range, the shortage of the bed stock is prompted, the insufficient organic waste gas treatment capacity is possibly caused, the emission reaching the standard is influenced, the high-pressure screw feeder 7 needs to be started to be supplemented with fresh catalyst, and the bed pressure drop is recovered to be within the set range.
Example four
As shown in fig. 4, an improved circulating fluidized bed catalytic combustion system for treating organic waste gas is also provided on the basis of the circulating fluidized bed catalytic combustion system for treating organic waste gas shown in fig. 3. In addition to the components in the third system, the fourth system further comprises a pre-filtering device, a pre-filtering devulcanizer 16 and a pre-filter 17, wherein the devulcanizer 16 and the pre-filter 17 are arranged on the organic waste gas main pipe 14 between the fluidized fan 15 and the heat exchanger 18.
And the system IV mainly aims at organic waste gas with high sulfur content and high dust. When the content of sulfide in the organic waste gas is high, the catalyst is poisoned, so that the catalytic activity is reduced and even lost; the too high dust concentration easily leads to the blockage of the elbow of the riser inlet main pipe 1, the fluidization air chamber 2 and the air distribution plate 3, in addition, the too high invalid dust amount accumulated in the riser 8 occupies a certain bed pressure drop, which can lead to the false report of the effective catalyst storage in the bed, and part of dust can also lead to the catalyst poisoning. Therefore, the sulfides and large-particle dusts in the exhaust gas need to be removed in advance.
In this embodiment, the method based on the fourth system includes, in addition to the steps described in the third system, a pre-filtering operation, specifically: before the organic waste gas with high sulfur content and high dust to be treated is sent into the fluidizing air chamber 2, organic sulfur and inorganic sulfur in the waste gas are removed by a desulfurizing tank 16, and then large-particle dust is removed by a prefilter 17.
EXAMPLE five
As shown in fig. 5, an improved circulating fluidized bed catalytic combustion system for treating organic waste gas is provided on the basis of the circulating fluidized bed catalytic combustion system for treating organic waste gas shown in fig. 4. In addition to the components of system four, system five further comprises a discharge pipe 4, and the discharge pipe 4 is arranged at the edge of the upper side of the air distribution plate 3. The system five mainly aims at the problems of catalyst deactivation and renewal. After the system operates for a period of time, the catalytic activity of partial catalyst particles is gradually reduced, and at the moment, the equivalent effective catalyst storage in the bed is reduced, so that the treatment capacity of the system on the organic waste gas is reduced, and the catalyst needs to be updated at irregular time.
In this embodiment, based on the usage of system five, in addition to the steps described in system four, the method further includes a catalyst regeneration operation, specifically: and after the system operates for a period of time, when the removal rate of VOCs components in the organic waste gas is reduced, opening a valve of the discharge pipe 4 to discharge a part of old catalyst with reduced catalytic activity, then opening the high-pressure screw feeder 7 to supplement fresh catalyst into the system, and keeping the bed pressure drop within a set range continuously.
The system of the invention has the advantages that the catalyst particles in the circulating fluidized bed catalytic combustion furnace are in a fluidized state, the gas-solid contact area is large, the catalytic efficiency is high, no valve switching part is arranged, the combustion temperature is effectively reduced by using the catalyst, the energy consumption is saved, the secondary pollution of NOx and the like generated at high temperature is avoided, the removal rate of VOCs is high, the operation is simple, and the long-term continuous and stable treatment of volatile organic waste gas can be realized.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical scheme according to the technical idea proposed by the present invention falls within the protection scope of the present invention; the technology not related to the invention can be realized by the prior art.

Claims (12)

1. A circulating fluidized bed catalytic combustion system for treating organic waste gas is characterized in that: the system comprises a circulating fluidized bed catalytic combustion furnace, a heat exchanger (18) and an electric heating component (9), the circulating fluidized bed catalytic combustion furnace comprises a fluidized air chamber (2), an air distribution plate (3), a lifting pipe (8), a separator (10) and a dipleg (11), the feed inlet of the fluidization wind chamber (2) is connected with an organic waste gas main pipe (14) with a fluidization fan (15) through a riser gas inlet main pipe (1), the upper discharge holes (803) of a riser (8) with electric heating parts (9) distributed on the periphery are connected with the feed inlet of a separator (10), a discharge port at the lower part of the separator (10) is connected with a feed port at the upper end of the dipleg (11), a discharge port at the lower end of the dipleg (11) is connected with a riser return pipe (802), the upper exhaust port of the separator (10) is connected with a heat exchanger (18) through a pipeline to recover the heat of the tail gas.
2. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: a hot gas inlet (181) of the heat exchanger (18) is connected with a top gas outlet of the separator (10) through a pipeline, a hot gas outlet (182) is connected with a tail gas flue (19), a cold gas inlet (184) is communicated with the organic waste gas main pipe (14), and a cold gas outlet (183) is communicated with the riser gas inlet main pipe (1); the purified hot tail gas leaving from the separator (10) enters a heat exchanger (18) to exchange heat with cold organic waste gas to be treated so as to recover the heat of the tail gas and preheat the organic waste gas to be treated, and the preheated organic waste gas to be treated is sent into a fluidized air chamber (2) of a circulating fluidized bed catalytic combustion furnace and enters a riser (8) through an air distribution plate (3).
3. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: a material returning valve (12) is arranged at the lower end of the dipleg (11), one inlet of the material returning valve (12) is connected with the lower end of the dipleg (11), the other inlet is connected with a riser gas inlet main pipe (1) through a gas inlet branch pipe with a material returning wind supercharging fan (13), and one outlet is connected with a material returning opening of a riser (8) through a riser gas returning pipe (802); catalyst particles flowing out of the dipleg (11) fall into a return valve (12), one path of gas separated from the riser gas inlet main pipe (1) enters the return valve (12) after being pressurized by a return air booster fan (13) so as to convey the catalyst particles in the return valve (12) to return into the riser (8) through a riser return pipe (802), and the circulating flow rate of the catalyst particles in the circulating fluidized bed catalytic combustion furnace can be adjusted by adjusting the outlet return air volume of the booster fan (13).
4. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: a high-pressure screw feeder (7) is arranged at a front wall feeding port (801) of the lifting pipe (8), and the high-pressure screw feeder (7) is arranged below the storage bin (6); catalyst particles in the riser (8) are fed from a feed bin (6) through a high-pressure screw feeder (7) from a front wall feed port (801) of the riser (8).
5. The circulating fluidized bed catalytic combustion system for treating organic exhaust gas according to claim 1 or 4, wherein: an upper pressure measuring point (502) and a lower pressure measuring point (501) are arranged on the lift pipe (8), the lower pressure measuring point (501) is arranged on the upper side of the air distribution plate (3), and the upper pressure measuring point (502) is arranged at the top of the inner cavity of the lift pipe (8); in the operation process, the bed pressure drop in the riser (8) is obtained through the upper pressure measuring point (502) and the lower pressure measuring point (501), and when the bed pressure drop is in a set range, the catalyst particle inventory in the riser (8) is normal without replenishing catalyst particles; when the bed pressure drop is less than the lower limit of the set range, the inventory of the catalyst particles in the riser (8) is insufficient, and the catalyst particles need to be supplemented, so that the bed pressure drop in the riser (8) is recovered to be within the set range.
6. The circulating fluidized bed catalytic combustion system for treating organic exhaust gas according to claim 1 or 4, wherein: the upside edge of air distribution plate (3) is equipped with row material pipe (4), and when finding organic waste gas desorption rate and reducing through monitoring the gaseous component concentration of VOCs in the organic waste gas of separator (10) export, open the valve of arranging material pipe (4) and in order to discharge partly catalytic activity reduction's old catalyst, then supply fresh catalyst granule in riser (8).
7. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: a desulfurizing tank (16) and a pre-filter (17) are arranged on an organic waste gas main pipe (14) between the fluidizing fan (15) and the heat exchanger (18), organic waste gas to be treated with high sulfur content and high dust is firstly subjected to organic sulfur and inorganic sulfur removal by the desulfurizing tank (16) and then large-particle dust removal by the pre-filter (17) before being sent to the fluidizing air chamber (2).
8. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 7, wherein: a dehumidifier is arranged on the organic waste gas main pipe (14) between the desulfurizing tank (16) and the prefilter (17).
9. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: the catalyst particles in the riser (8) are catalyst powder belonging to Geldart group A or group B particles and the catalyst particles in the riser (8) are in fast fluidization during operation.
10. The circulating fluidized bed catalytic combustion system for treating organic exhaust gas according to claim 1 or 9, wherein: and the inner walls of the riser (8) and the separator (10) are coated with anti-wear castable.
11. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: the air distribution plate (3) is a microporous plate type or a hood type; and the separator (10) is a two-stage high-efficiency cyclone separator.
12. The circulating fluidized bed catalytic combustion system for treating organic waste gas according to claim 1, wherein: the whole loop of the circulating fluidized bed catalytic combustion furnace is insulated.
CN202010675788.1A 2020-07-14 2020-07-14 Circulating fluidized bed catalytic combustion system for treating organic waste gas Pending CN111735071A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114250092A (en) * 2022-01-12 2022-03-29 清华大学 System and method for reducing emission of low-concentration combustible gas

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114250092A (en) * 2022-01-12 2022-03-29 清华大学 System and method for reducing emission of low-concentration combustible gas

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