CN113122674A - All-dry method converter gas purification and recovery system and purification and recovery method - Google Patents
All-dry method converter gas purification and recovery system and purification and recovery method Download PDFInfo
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- CN113122674A CN113122674A CN202110410818.0A CN202110410818A CN113122674A CN 113122674 A CN113122674 A CN 113122674A CN 202110410818 A CN202110410818 A CN 202110410818A CN 113122674 A CN113122674 A CN 113122674A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/38—Removal of waste gases or dust
- C21C5/40—Offtakes or separating apparatus for converter waste gases or dust
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C2100/00—Exhaust gas
- C21C2100/02—Treatment of the exhaust gas
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C2100/00—Exhaust gas
- C21C2100/06—Energy from waste gas used in other processes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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Abstract
The invention provides a full-dry converter gas purification and recovery system and a purification and recovery method, which belong to the field of energy conservation and emission reduction, and comprise a dust-catching gas-collecting hood, a gravity dust collector, a gas enricher, a waste heat boiler, a bag-type dust collector, a pressurizing unit and an analysis and detection unit; the dust-catching gas-collecting hood is communicated with an exhaust port of the converter; the gravity dust collector is communicated with the dust-catching gas-collecting hood through a cooling flue; the gas enriching device is communicated with the gravity dust remover; the waste heat boiler is communicated with the gas enriching device; the bag-type dust collector is communicated with the waste heat boiler; the pressurizing unit is used for pressurizing the secondary purified gas and then sending the pressurized secondary purified gas into the silencer for silencing; the analysis and detection unit is used for detecting CO and O in the pressurized and silenced coal gas2The content of (A); when CO and O in the coal gas2Recovering when the content meets the preset value. The invention can save a large amount of water resources and electric resources, recycle a large amount of converter gas which does not meet the existing recycling standard, avoid the waste of diffusion and the pollution to the atmosphere, and improve the heat value of the converter gas.
Description
Technical Field
The invention belongs to the technical field of energy conservation and emission reduction, and particularly relates to an all-dry converter gas purification and recovery system and a purification and recovery method based on the all-dry converter gas purification and recovery system.
Background
Along with the aggravation of environmental problems and global energy problems, especially the huge demand of China on the steel output, the metallurgical industry of China faces unprecedented opportunities and challenges. Based on this, the research on the process of purifying and recycling the converter gas is a major problem to be solved by a steel mill and is also a technical guarantee for realizing negative energy steelmaking.
In the oxygen blowing smelting period, the converter generates high-temperature flue gas containing a large amount of CO and iron dust, the temperature of the high-temperature flue gas reaches 1400-1600 ℃, and the purified and recovered converter gas can be used as a high-quality fuel and is an important secondary energy source for the production of iron and steel enterprises. If the flue gas is arbitrarily diffused after being discharged from the furnace mouth, the environment is polluted, and a large amount of energy and useful substances are wasted. Calculation shows that the maximum ideal value of coal gas recovery of a ton steel converter under ideal working conditions is 128.8m3T, the average heating value can reach 8.8MJ/m3The above. At present, the recovery amount of converter gas of a common iron and steel enterprise is 60-80 m3The heat value is 6.7-7.1 MJ/m3Therefore, the coal gas recovery work of the converter still needs to be further enhanced and has great potential.
At present, converter gas recovery technology generally adopts an OG wet method and a semi-dry method purification recovery system. The OG wet process has high water consumption, low waste heat recovery and high system resistance; the semi-dry process has the problems of high nitrogen consumption, dust adhesion of fan impellers and the like.
Disclosure of Invention
The embodiment of the invention provides a system and a method for purifying and recovering converter gas by an all-dry method, which can reduce water consumption and improve waste heat recovery and gas recovery rate.
In a first aspect, an embodiment of the present invention provides an all-dry converter gas purification and recovery system, including: the system comprises a dust-catching gas-collecting hood, a gravity dust collector, a gas enriching device, a waste heat boiler, a bag-type dust collector, a pressurizing unit and an analysis and detection unit; the dust-catching gas-collecting hood is communicated with an exhaust port of the converter and is used for collecting coal gas discharged by the converter; the gravity dust collector is communicated with the dust-catching gas-collecting hood through a cooling flue and is used for coarse dust removal of the coal gas to obtain primary purified coal gas; the gas enriching device is communicated with the gravity dust collector and is used for converting primary purified gas; the waste heat boiler is communicated with the gas enriching device, recovers heat energy through heat exchange and cools the primary purified gas; the bag-type dust collector is communicated with the waste heat boiler and is used for fine dust collection and purification of the cooled primary purified gas to obtain secondary purified gas; collecting the dust discharged by the bag-type dust collector and the dust discharged by the gravity dust collector into a dust storage bin; the pressurizing unit is used for pressurizing the secondary purified gas and then sending the pressurized secondary purified gas into the silencer for silencing; the analysis and detection unit is used for detecting CO and O in the pressurized and silenced coal gas2The content of (A); when CO and O in the coal gas2Recovering when the content meets the preset value, and diffusing when the content does not meet the preset value; the recovered coal gas is cooled by a coal gas cooler and then is recovered to a coal gas cabinet for reuse.
In a second aspect, the embodiment of the present invention further provides an all-dry method converter gas purification and recovery method, which is based on the recovery system as claimed in claim 1, and includes the following steps:
cooling the coal gas collected by the dust-catching gas-collecting hood through a cooling flue to below 1200 ℃;
the cooled coal gas enters a gravity dust collector for coarse dust removal to obtain the coal gas with the smoke content less than or equal to 30g/m3The primary purified gas;
the obtained primary purified coal gas is gasified and reacted by a coal gas enriching device to lead the volume percentage of CO to be more than 80 percent2Converting into CO to improve the recovery of converter gas;
the coal gas gasified by the coal gas enriching device enters a waste heat boiler to recover heat energy, and the temperature of the coal gas is reduced to be below 150 ℃;
the waste heat recovered coal gas is subjected to fine dust removal by a bag-type dust remover, and the dust content of the obtained coal gas is less than or equal to 10mg/m3；
The pressurized gas is analyzed and detected by an analysis and detection unit to detect that CO is more than or equal to 30 percent and O in the gas2When the content is less than or equal to 2 percent, the coal gas components meet the preset requirements;
when the components of the coal gas meet the preset requirements, the coal gas is cooled to below 70 ℃ by a coal gas cooler and enters a coal gas cabinet for recycling;
when the coal gas components do not meet the preset requirements, the coal gas components are diffused through a diffusing chimney.
With reference to the second aspect, in a possible implementation manner, the lower opening of the dust-collecting gas-collecting hood is in a horn shape, and the micro-pressure difference inside and outside the dust-collecting gas-collecting hood is adjusted to be 0 ± 10Pa by the micro-pressure difference automatic adjusting device, so as to keep the air suction coefficient to be 0.1.
With reference to the second aspect, in a possible implementation manner, the cooling flue is of a dividing wall type heat exchange structure, and the cooling flue is an inverted U-shaped pipeline with a length of 12-16 meters.
In combination with the second aspect, in a possible implementation manner, the internal temperature of the gas concentrator is between 900 ℃ and 1250 ℃.
With reference to the second aspect, in one possible implementation manner, the waste heat recovery pipeline in the waste heat boiler is an elliptical finned tube.
With reference to the second aspect, in one possible implementation manner, the filter bag of the bag-type dust collector employs a PTEF membrane filter material.
In combination with the second aspect, in a possible implementation manner, the diameter of the micropores of the PTEF membrane-covered filter material is between 0.2 and 3 μm.
With reference to the second aspect, in one possible implementation manner, the diffusing chimney adopts a staged cyclone burner, and the air inlet is a four-corner tangential air inlet.
With reference to the second aspect, in one possible implementation manner, the gas cooler and the circulating cooling water in the external water purification tank are in recuperative heat exchange.
Compared with the prior art, the all-dry converter gas purification and recovery system and the purification and recovery method disclosed by the embodiment of the application have the following effects: (1) the temperature of the coal gas can be reduced to below 1200 ℃ after passing through the cooling flue, the cooled coal gas can directly enter the gravity dust collector for dust removal, so that the serious waste of heat and water resources and the generated large amount of sludge caused by instantly cooling the coal gas after water vapor or nitrogen precipitation atomization in the traditional coal gas cooler are avoided, and the defects of heavy moisture, high content of impurity gas and low qualified coal gas recovery amount in the subsequent coal gas are avoided; (2) the gas after coarse dust removal enters a gas enriching device, and the content of CO in the gas is increased through gasification reaction, so that the recycling of the gas is improved; (3) the enriched coal gas enters the waste heat boiler with the adjustable outlet flue gas temperature, the temperature of the flue gas in the waste heat boiler is reduced from 1200 ℃ to below 150 ℃, the flue gas temperature at the outlet of the waste heat boiler is adjusted within a proper range, and then the flue gas enters the bag-type dust collector for fine dust removal, so that the dust removal effect can be improved, and the dust content of the outlet flue gas is reduced.
The all-dry method converter gas purification and recovery system and the purification and recovery method provided by the invention save a large amount of water resources and electric resources, so that a large amount of converter gas which does not meet the existing recovery standard can be recycled, the waste of diffusion and the pollution to the atmosphere are avoided, the calorific value of the converter gas is improved, the converter gas can be more scientifically utilized, and the steelmaking cost is reduced.
Drawings
FIG. 1 is a schematic structural diagram of an all-dry converter gas purification and recovery system provided in an embodiment of the present invention;
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a system for purifying and recycling coal gas of an all-dry converter provided by the present invention will now be described.The all-dry converter gas purification and recovery system comprises a dust-catching gas-collecting hood, a gravity dust collector, a gas enriching device, a waste heat boiler, a bag-type dust collector, a pressurizing unit and an analysis and detection unit; the dust-catching gas-collecting hood is communicated with an exhaust port of the converter and is used for collecting coal gas discharged by the converter; the gravity dust collector is communicated with the dust-catching gas-collecting hood through a cooling flue and is used for coarse dust removal of coal gas to obtain primary purified coal gas; the gas enriching device is communicated with the gravity dust collector and is used for converting primary purified gas; the waste heat boiler is communicated with the gas enriching device, recovers heat energy through heat exchange, and cools primary purified gas; the bag-type dust collector is communicated with the waste heat boiler and is used for fine dust collection and purification of the cooled primary purified gas to obtain secondary purified gas; collecting the dust discharged by the bag-type dust collector and the dust discharged by the gravity dust collector into a dust storage bin; the pressurizing unit is used for pressurizing the secondary purified gas and then sending the pressurized secondary purified gas into the silencer for silencing; the analysis and detection unit is used for detecting CO and O in the pressurized and silenced coal gas2The content of (A); when CO and O in the coal gas2Recovering when the content meets the preset value, and diffusing when the content does not meet the preset value; the recovered coal gas is cooled by a coal gas cooler and then is recovered to a coal gas cabinet for reuse.
Compared with the prior art, the all-dry converter gas purification and recovery system provided by the embodiment has the advantages that (1) the temperature of the gas can be reduced to below 1200 ℃ after passing through the cooling flue, and the cooled gas can directly enter the gravity dust collector for dust removal, so that the serious waste of heat and water resources and a large amount of sludge generated due to the fact that the gas is instantly cooled after water vapor or nitrogen precipitation atomization is adopted in a traditional gas cooler are avoided, and the defects of heavy moisture, high content of impurity gas and low recovery amount of qualified gas in the subsequent gas are avoided; (2) the gas after coarse dust removal enters a gas enriching device, and the content of CO in the gas is increased through gasification reaction, so that the recycling of the gas is improved; (3) the enriched coal gas enters the waste heat boiler with the adjustable outlet flue gas temperature, the temperature of the flue gas in the waste heat boiler is reduced from 1200 ℃ to below 150 ℃, the flue gas temperature at the outlet of the waste heat boiler is adjusted within a proper range, and then the flue gas enters the bag-type dust collector for fine dust removal, so that the dust removal effect can be improved, and the dust content of the outlet flue gas is reduced.
On the basis of the recovery system, the gas chambers are divided into two types, one type is used for recovering low-calorific-value gas, and the other type is used for recovering high-calorific-value gas. Compared with the converter gas with high heat value, the low heat value gas has less combustible substances and low flame temperature, and in order to stabilize the productivity and the quality, constant gas heat input needs to be ensured, and under the condition of low heat value, the gas input needs to be increased. Therefore, the gas tank is divided into a high-calorific value gas tank and a low-calorific value gas tank, and qualified gas passes through the carbon monoxide detection device and then enters the tanks according to the calorific value, so that the requirements of different users are met.
The all-dry method converter gas purification and recovery system provided by the invention can save a large amount of water resources and electric resources, so that a large amount of converter gas which does not meet the existing recovery standard can be recycled, the waste of diffusion and the pollution to the atmosphere are avoided, the calorific value of the converter gas is improved, the converter gas can be more scientifically utilized, and the steelmaking cost is reduced.
Wherein, the enriching system and the gas enriching device in figure 1 are the same technical terms.
Based on the same inventive concept, referring to fig. 1, the embodiment of the present application further provides an all-dry method converter gas purification and recovery method, which includes the following steps:
firstly, cooling the coal gas collected by the dust-catching gas-collecting hood through a cooling flue to below 1200 ℃;
step two, the cooled coal gas enters a gravity dust collector for coarse dust removal to obtain the coal gas with the smoke content less than or equal to 30g/m3The primary purified gas;
thirdly, the obtained primary purified coal gas is gasified and reacted by a coal gas enriching device to lead the volume percentage of CO to be more than 80 percent2Converting into CO to improve the recovery of converter gas;
step four, the gas gasified by the gas enriching device enters a waste heat boiler to recover heat energy, and the temperature of the gas is reduced to be below 150 ℃;
step five, fine dust removal is carried out on the waste heat recovered coal gas by a bag-type dust collector, and the dust content of the obtained coal gas is less than or equal to 10mg/m3；
Step six, the pressurized coalGas, the CO content of the gas is detected to be more than or equal to 30 percent and O content is detected to be more than or equal to 30 percent by an analysis and detection unit2When the content is less than or equal to 2 percent, the coal gas components meet the preset requirements;
seventhly, when the gas components meet the preset requirements, cooling the gas components to below 70 ℃ through a gas cooler, and recycling the gas components in a gas chamber;
and step eight, when the coal gas components do not meet the preset requirements, diffusing the coal gas components through a diffusing chimney.
On the basis of the recovery method, optionally, the gas chamber is provided with an overhauling device, a communicating pipe is added between the inlet and outlet pipelines of the gas chamber, when the gas chamber is overhauled, the valve of the gas chamber is closed, and at the moment, the gas chamber is withdrawn from operation. The communication of the inlet and outlet pipelines does not influence the normal recovery and external supply of the coal gas, and meanwhile, the coal gas cabinet can quit the operation at any time, thereby reducing the coal gas loss caused by the full coal gas cabinet or the failure of the coal gas cabinet. According to analysis and detection, the coal gas meeting the preset requirements is further divided into a high-heat-value gas cabinet and a low-heat-value gas cabinet, the high-heat-value gas cabinet and the low-heat-value gas cabinet are respectively recycled, accurate utilization is achieved, and the utilization effect is improved.
In the first step, the automatic lifting dust-catching gas-collecting hood with the horn-shaped lower opening is arranged, and a micro-pressure difference automatic adjusting device is adopted, and the micro-pressure difference automatic adjusting device controls the micro-pressure difference inside and outside the dust-catching gas-collecting hood to be 0 +/-10 Pa through testing the pressure of the dust-catching gas-collecting hood and automatically controlling a flue gas flow adjusting valve. The dust-catching gas-collecting hood is controlled to lift by utilizing the analysis of the furnace gas analysis system and adopting an automatic hood-lowering device. Through analysis, the dust-catching gas-collecting hood is lifted in the pre-burning period and the post-burning period of the blowing, enough air is sucked into the flue and completely combusted with CO in the furnace gas at the furnace mouth as far as possible, and the heat value of the part of fuel is recovered through a subsequent waste heat recovery device (a waste heat boiler). Lowering the cover in the middle blowing period (recovery period), keeping the micro differential pressure of the furnace mouth, keeping the air suction coefficient about 0.1, avoiding a large amount of air from entering a flue, ensuring the high quality and extremely low oxygen content of converter gas, and effectively avoiding explosion; the smoke escape caused by the fact that the traditional smoke hood cannot accommodate the furnace gas amount with large instantaneous change is avoided; meanwhile, the air suction amount of the furnace mouth is controlled, and the quality of coal gas is improved.
In the second step, the cooling flue adopts a dividing wall type heat exchange structure, and the cooling flue is an inverted U-shaped pipeline with the length of 12-16 meters. The cooling flue adopts the bent pipeline of "U" shape of falling and establishes temperature control system, the cooling rate behind multiplicable coal gas process cooling flue, avoided adopting vapor or nitrogen gas precipitation atomizing in the traditional coal gas cooler, carry out the serious waste of heat and the water resource that cools off in the twinkling of an eye to coal gas and the problem of a large amount of mud of production, avoided the defect that moisture is heavy in the follow-up coal gas, impurity gas content is high, qualified coal gas recovery volume is few simultaneously. The converter gas is firstly cooled to 1100-1200 ℃ through a cooling flue, and then enters a gravity dust collector for primary dust removal, most of particles with the particle size of more than 50 microns are separated, and a good foundation is provided for subsequent fine dust removal.
In the embodiment, the cooling flue and the gas cooler are both in dividing-wall type heat exchange type cooling, and perform dividing-wall type heat exchange with circulating cooling water in an external water purifying tank, so that the gas cooler adopting conventional direct spray cooling is avoided, and the anhydrous cooling in the whole process of gas is realized; a large amount of water resources are saved, the environment is protected, energy is saved, the direct contact between coal gas and water can be avoided through the heat exchange, and the adhesion is avoided, so that the ash adhesion phenomenon of the equipment is avoided.
In the process of enriching the coal gas in the step three, the primary purified coal gas after coarse dust removal by the gravity dust remover enters a coal gas enriching device, and CO with the volume percentage of more than 80 percent in the converter coal gas is subjected to gasification reaction2The gas after being enriched and gasified enters a waste heat boiler with adjustable outlet flue gas temperature through a one-way check valve after being buffered and stabilized by a storage tank for waste heat recovery. Wherein, the outer side of the gas enriching device is provided with a heat insulation layer and an automatic temperature control system, so that the internal temperature of the gas enriching device is between 900 ℃ and 1250 ℃. Three rows of nozzles are adopted in the gas enriching device, CDQ powder is sprayed, and the CDQ powder is fully contacted with the gas at high temperature, so that CO is increased2Conversion efficiency to CO. The CDQ powder is dust removed in the coke dry quenching environment of a coke-oven plant, and the recycling of wastes is realized by utilizing the CDQ powder.
In the waste heat recovery process in the step four, the waste heat recovery pipeline in the waste heat boiler is the oval finned tube, no dust is attached in the heat exchange process, and dry dust can flow away instantly after passing through the surface. The oval finned pipeline comprises an oval pipeline body with reinforcing ribs in the middle and fins arranged on two sides of the oval pipeline body respectively, the cross section of the oval finned pipeline is fusiform, and the long axis of the cross section is overlapped with the long axis of the oval pipeline body.
In the fine dust removal process of the fifth step by the bag-type dust remover, the pulse blowing bag-type dust remover is adopted and mainly comprises a filter chamber, a filter bag, a gas purifying chamber, an ash discharging valve, a pulse blowing device, an electric cabinet and the like. The specific flow is that dusty gas enters an ash hopper from an air inlet pipeline at the lower part of the dust remover through a guide plate, coarse-grained dust falls into the ash hopper under the actions of collision of the guide plate, reduction of gas speed and the like, and other fine-grained dust enters a filter bag chamber along with gas. The deposited dust on the filter bag is removed by adopting a method of blowing pulse air flow, and the removed dust falls into a dust hopper and is discharged to a dust conveying device through a double-layer dust discharging valve. Meanwhile, the pulse bag type dust collector adopts the optimum combined blowing pressure of 347.83P/kPa for ash removal; the length of the filter bag is 9.652L/m; the diameter of the filter bag is 143.04D/mm; nozzle diameter 19.13d/mm optimized target 2.294F/kPa.
When the conventional filter material is used for filtering, fine dust particles can penetrate into the material through micropores in the surface of the filter material, so that the pores in the filter material are gradually blocked, the energy consumption of a system is increased, and the service life of the filter material is influenced. The PTEF (polytetrafluoroethylene) membrane filter material is a novel filter material formed by compounding a layer of Polytetrafluoroethylene (PTFE) membrane on the surface of a common filter material, and the PTEF microporous membrane is generally obtained by mixing PTEF dispersion resin with other additives, rolling the mixture to form a sheet, stretching the sheet in two directions, and carrying out hot-press molding on the filter material and the membrane by adopting a high-temperature hot-pressing method. The PTEF microporous membrane subjected to biaxial tension is coated on the surface of a traditional filter material (cloth or felt), the surface is of a spatial three-dimensional net structure, dust cannot enter the filter material through the microporous membrane due to the three-dimensional structure, and therefore high-efficiency filtration is achieved, the PTEF microporous membrane has small pore size and porosity, good hydrophobicity and strong self-cleaning capacity. The membrane making process can control the aperture to be 0.2-3 mu m, and can quickly and effectively intercept the ultrafine dust calculated by micron. Because the PTEF microporous membrane is smooth and has lower surface tension, dust can naturally fall off after reaching a certain thickness, dust which cannot fall off still needs to be removed by adopting a pulse dust removal mode, the porosity is not changed after dust removal, and the dust removal efficiency is always very high; and the chemical stability is good, the microporous membrane can be used for high temperature of 250-300 ℃, the surface of the membrane is microporous, the surface is close to real surface filtration, and the filtration resistance is small. By using the filtering material, the filtering efficiency can be improved to 99.99% from 99% of the high-efficiency filtering material, the real surface filtration is realized by the film filtering material, the resistance is greatly reduced, and the dust removal efficiency is improved.
Aiming at the pulse blowing bag-type dust collector, the installation end of the blowing pipe adopts a flattening process, so that the pipe wall of the transition part of the blowing pipe and the installation part is thinned, and the blowing pipe is broken under the action of pulse force, the structure of the blowing pipe is improved, the original flattened installation part structure is changed into a structural form of combining 45 round steel and an iron plate, and the structural form is connected by adopting a welding process. The influence of pulse force on the structure and the function of the blowing pipe is reduced after improvement, the dust remover continuously and stably operates, and the replacement and cleaning times of the filter bag are reduced in the same ratio. Meanwhile, the surface of the blowing pipe is subjected to chromium plating treatment in consideration of the fact that the soot is high in alkalinity and can corrode the blowing pipe.
On the basis of the bag type dust collector, a gas detector is arranged at a gas outlet of the bag type dust collector to detect the quality of gas; a double-layer pneumatic ash discharge valve is arranged to control the accumulation amount of dust in the bag type dust collector; the explosion-proof device is arranged, an emergency shut-off valve is adopted, a explosion-proof membrane is installed, the explosion-proof membrane is realized by rapidly starting a pneumatic spring valve through an infrared flame sensor, the emergency shut-off valve which is installed far enough away from the sensor can be triggered, and flame or explosive waves and explosives are prevented from being spread to other places to form secondary explosion.
And step six, pressurizing the coal gas discharged by the bag-type dust collector through a variable-frequency axial flow fan, silencing the coal gas after entering a silencer, and detecting components through an analysis detection unit. The analysis and detection unit adopts a time-of-flight mass spectrometer and mainly comprises a sampling system, a mass spectrometer, an automatic control system and a data transmission system. Sampling points of the mass spectrometer are positioned at the top of the converter and in front of a waste gas cooling and dedusting system, the mass spectrometer can provide continuous furnace gas information including pressure, temperature and components, and the analysis speed is high and the precision is high; meanwhile, the analysis components are more, the precision is high, and the measurement error can be ensured to be within +/-0.1%; and the furnace gas component measured by the mass spectrometer can be utilized to more accurately control the lifting of the converter smoke hood so as to adjust the sucked air quantity and the furnace gas component and further improve the gas recovery rate. In the specific recovery, a field control station is arranged on the field, and the automatic action and the automatic control of each device or equipment in the system can be realized through the control of the field control station.
In the seventh step, the gas cooler and the circulating cooling water in the external water purifying tank are subjected to dividing wall type heat exchange, so that the conventional gas cooler which is directly sprayed for cooling is avoided, and the anhydrous cooling of the whole process of the gas is realized.
In the eighth step, the diffusing chimney adopts a graded cyclone burner, and the structure of the air inlet is a four-corner tangential air inlet, so that the requirement that the mixed gas is fully mixed along the wall surface in the process of entering the burner through the tangential direction is met. Through staged combustion, the air distribution mode is improved, the combustion flame temperature is reduced, the gas mixing can be effectively enhanced, and the method is an effective mode for realizing efficient clean combustion and low pollutant emission of the converter diffused gas.
The all-dry method converter gas purification and recovery method provided by the invention can realize the following obvious effects:
firstly, the heat value of the recovered gas per ton of steel can be improved. The calculation result shows that after the converter gas is enriched, the mass percentage of CO can be averagely improved by more than 20 percent, and the heat value of the converter gas can be averagely improved by more than 55 percent. If the air combustion coefficient alpha is less than or equal to 0.1, the coal gas recovery rate can reach 91 percent, and the recovery rate is 90 percent; the recovery amount of converter gas is 94.48{ Nm } < Lambda > 3/t; recovery and recovery of converter gasThe yield and quality are greatly improved; the coal gas recovery rate is improved from 84.17 percent to 90 percent, and the heat value of the coal gas is 7250kJ/Nm3Increased to over 9100kJ/Nm3。
Secondly, by the method, a large amount of converter gas which does not meet the existing recovery standard is recovered, the waste of diffusion and the pollution to the atmosphere are avoided, the calorific value of the converter gas is improved, the converter gas can be more scientifically utilized, and the steelmaking cost is reduced.
Thirdly, a large amount of water resources and electric resources are saved through the full dry method.
Fourthly, on the premise of ensuring the same high dust removal efficiency, the manufacturing cost is lower than that of an electric dust remover.
Fifthly, the cloth bag dust collector adopts a PTEF membrane filter material, has good chemical stability, can be used at high temperature of 250-300 ℃, has high filtering efficiency which can be improved from 99 percent of high-efficiency filtering material to 99.99 percent, and has high dust removal efficiency, and the dust concentration of gas at the outlet of the dust collector is 10mg/m3In addition, the method has higher classification efficiency on fine dust with submicron particle size.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. An all-dry converter gas purification and recovery system is characterized by comprising:
the dust-catching gas-collecting hood is communicated with an exhaust port of the converter and is used for collecting coal gas discharged by the converter;
the gravity dust collector is communicated with the dust-catching gas-collecting hood through a cooling flue and is used for coarse dust removal of the coal gas to obtain primary purified coal gas;
the gas enriching device is communicated with the gravity dust collector and is used for converting the primary purified gas;
the waste heat boiler is communicated with the gas enriching device, recovers heat energy through heat exchange and cools the primary purified gas;
the bag-type dust collector is communicated with the waste heat boiler and is used for fine dust collection and purification of the cooled primary purified gas to obtain secondary purified gas; collecting the dust discharged by the bag-type dust collector and the dust discharged by the gravity dust collector into a dust storage bin;
the pressurizing unit is used for pressurizing the secondary purified gas and then sending the pressurized secondary purified gas into the silencer for silencing;
an analysis and detection unit for detecting CO and O in the pressurized and silenced gas2The content of (A); when CO and O in the coal gas2Recovering when the content meets the preset value, and diffusing when the content does not meet the preset value; and
the recovered coal gas is cooled by a coal gas cooler and then is recovered to a coal gas cabinet for reuse.
2. An all-dry method converter gas purification and recovery method, which is characterized in that the method is based on the recovery system of claim 1 and comprises the following steps:
cooling the coal gas collected by the dust-catching gas-collecting hood through a cooling flue to below 1200 ℃;
the cooled coal gas enters a gravity dust collector for coarse dust removal to obtain the coal gas with the smoke content less than or equal to 30g/m3The primary purified gas;
the obtained primary purified coal gas is gasified and reacted by a coal gas enriching device to lead the volume percentage of CO to be more than 80 percent2Converting into CO to improve the recovery of converter gas;
the coal gas gasified by the coal gas enriching device enters a waste heat boiler to recover heat energy, and the temperature of the coal gas is reduced to be below 150 ℃;
the waste heat recovered coal gas is subjected to fine dust removal by a bag-type dust remover to obtain the coal gas with the dust content less than or equal to 10mg/m3The secondary purification of the coal gas;
the pressurized secondary purified gas is analyzed and detected by an analysis and detection unit to detect that CO is more than or equal to 30 percent and O is in the gas2When the content is less than or equal to 2 percent, the coal gas components meet the preset requirements;
when the components of the coal gas meet the preset requirements, the coal gas is cooled to below 70 ℃ by a coal gas cooler and enters a coal gas cabinet for recycling;
when the coal gas components do not meet the preset requirements, the coal gas components are diffused through a diffusing chimney.
3. The dry method converter gas purification and recovery method according to claim 2, wherein the lower opening of the dust-collecting gas-collecting hood is trumpet-shaped, and the micro-pressure difference inside and outside the dust-collecting gas-collecting hood is adjusted to 0 ± 10Pa by a micro-pressure difference automatic adjusting device, so as to keep the air suction coefficient to 0.1.
4. The all-dry method converter gas purification and recovery method according to claim 2, wherein the cooling flue adopts a dividing wall type heat exchange structure, is an inverted U-shaped pipeline and has a length of 12-16 m.
5. The method for purifying and recovering converter gas by the all-dry method according to claim 2, wherein the temperature inside the gas enriching device is 900 to 1250 ℃.
6. The purification and recovery method of full dry converter gas according to claim 2, wherein the waste heat recovery pipeline in the waste heat boiler is an elliptical finned tube.
7. The all-dry method converter gas purification and recovery method according to claim 2, wherein a filter bag of the bag-type dust remover adopts a PTEF membrane filter material.
8. The all-dry method converter gas purification and recovery method according to claim 7, wherein the diameter of the micropores of the PTEF membrane-coated filter material is 0.2-3 μm.
9. The all-dry method converter gas purification and recovery method according to claim 2, wherein the diffusion chimney adopts a graded cyclone burner, and the structure of the gas inlet is a four-corner tangential gas inlet.
10. The method for purifying and recycling converter gas by using the all-dry method according to claim 2, wherein the gas cooler and the circulating cooling water in the external water purifying tank are in recuperative heat exchange.
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