CN114181742A - Blast furnace gas source treatment system - Google Patents
Blast furnace gas source treatment system Download PDFInfo
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- CN114181742A CN114181742A CN202111335470.XA CN202111335470A CN114181742A CN 114181742 A CN114181742 A CN 114181742A CN 202111335470 A CN202111335470 A CN 202111335470A CN 114181742 A CN114181742 A CN 114181742A
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/02—Dust removal
- C10K1/024—Dust removal by filtration
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/002—Removal of contaminants
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/002—Removal of contaminants
- C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/002—Removal of contaminants
- C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
- C10K1/004—Sulfur containing contaminants, e.g. hydrogen sulfide
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/20—Purifying combustible gases containing carbon monoxide by treating with solids; Regenerating spent purifying masses
- C10K1/22—Apparatus, e.g. dry box purifiers
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/32—Purifying combustible gases containing carbon monoxide with selectively adsorptive solids, e.g. active carbon
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/34—Purifying combustible gases containing carbon monoxide by catalytic conversion of impurities to more readily removable materials
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Abstract
The invention belongs to the technical field of blast furnace gas source treatment, and particularly discloses a blast furnace gas source treatment system, which comprises a front-end dry dechlorination pretreatment and hydrolysis conversion system and a rear-end dry desulphurization system. The method specifically comprises the following steps: the blast furnace gas is led out from a gas main pipe after being dedusted by a cloth bag, dechlorination treatment is carried out by dry dechlorination pretreatment, a small amount of hydrocarbons and dust substances can be adsorbed at the same time, the effects of pretreatment and subsequent hydrolytic agent protection are achieved, then the blast furnace gas enters a hydrolysis conversion system, and the treated gas is led into a TRT power generation device or a pressure reducing valve bank through a gas pipeline to complete front end treatment; and the rear end of the system enters a rear-end dry-method desulfurization system from the TRT power generation device, and finally the SO2 at the discharge port of the blast furnace gas terminal combustion user reaches the ultralow emission standard. The investment and the operating cost of the environmental protection facility are saved, the secondary pollution is not generated, the operation is stable and reliable, and the subsequent operation and maintenance are simple.
Description
Technical Field
The invention belongs to the technical field of blast furnace gas source treatment, and particularly relates to a blast furnace gas source treatment system.
Background
Blast furnace gas is a byproduct combustible gas in the blast furnace ironmaking production process, and comprises the approximate components of carbon dioxide, carbon monoxide, hydrogen, nitrogen, hydrocarbons and a small amount of sulfides, wherein 75 percent of the sulfides are organic sulfur, and 25 percent of the sulfides are inorganic sulfur blast furnace gas, and is characterized by low calorific value, large gas amount, high total sulfur, high chlorine and high dust, and SO which causes the tail gas emission of end users after being sent to the end users such as a blast furnace hot blast stove, a steel rolling heating furnace, a gas power generation furnace and the like as fuel to be combusted2The concentration exceeds the standard, and if the concentration is required to meet the requirement of ultralow emission, a plurality of sets of SO removal devices are required to be arranged at the terminal2The environment-friendly device has large investment and high operation management cost, and the whole process pipeline equipment has serious potential safety hazard in the aspect of corrosion.
In the early stage, the emission standard requirement of SO2 in flue gas of end users such as blast furnace hot blast stoves and the like is 100mg/Nm3The following. Therefore, the blast furnace gas purification process only carries out two-stage dust removal for pretreatment and a bag-type dust remover, and has no corresponding treatment measures for sulfides.
Later stage, part of areas require SO in flue gas of end users such as blast furnace hot blast stoves2Is required to be 50mg/Nm3 or less. The usual route is only to inorganic sulfur (mainly H)2S) wet removing, namely, newly building a desulfurizing tower, adopting an alkaline solvent as a circulating absorbent to neutralize hydrogen sulfide in coal gas, thereby reducing SO generated by end users after combustion2The concentration of (c). The process has more route configuration and complex operation and maintenance, and because of adopting alkali liquor, the equipment and the pipeline have the requirement of corrosion prevention, the desulfurization removal rate is limited, and secondary pollutants such as wastewater and the like are generated.
With the coming of the stricter ultra-low emission policy of the steel industry, the desulfurization process route is also changed from the original simple removal of inorganic sulfur into the combined treatment of organic sulfur and inorganic sulfur. The commonly used treatment processes are: adsorption regeneration desulfurization process, hydrolysis conversion and wet desulfurization process.
The adsorption regeneration desulfurization process has the following disadvantages:
(1) the process is mainly positioned in a TRT power generation device or a low-pressure low-temperature gas pipe network at the rear end of a pressure reducing valve bank, and the resistance of the system has great influence on the pressure of a terminal gas user so as to influence the normal operation of the TRT power generation device;
(2) the process is complex, auxiliary processes such as heating, refrigerating, analyzing and the like need to be configured, the operation and maintenance workload is large, and the energy consumption is high;
(3) the adsorbent used is generally supplied exclusively and is relatively expensive.
The hydrolytic conversion and wet desulphurization processes have the following disadvantages:
the rear end of the process route is set to be wet desulphurization, namely alkali liquor is required to be sprayed to react with inorganic sulfur, and secondary pollutants such as a large amount of wastewater are generated and need to be further treated.
Therefore, providing a new blast furnace gas source treatment system is a technical problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
The invention aims to overcome the defects of secondary pollutants such as waste water and the like generated by blast furnace gas treatment and higher investment and operation cost in the prior art, and provides a blast furnace gas source treatment system.
The invention provides a blast furnace gas source treatment system, which comprises a bag type dust collector, a gas inlet online monitoring device, a dechlorination pretreatment tower, a hydrolysis conversion tower, a TRT power generation device, a dry desulfurization tower, a gas outlet online monitoring device and a gas user, wherein the bag type dust collector is communicated with a blast furnace gas outlet through a pipeline in sequence;
an inlet valve bank of a dechlorination pretreatment tower is arranged at one end, close to the dechlorination pretreatment tower, of a pipeline between the air inlet online monitoring device and the dechlorination pretreatment tower;
a hydrolysis conversion tower outlet valve bank is arranged at one end, close to the hydrolysis conversion tower, of the pipeline between the hydrolysis conversion tower and the TRT power generation device;
a desulfurizing tower inlet valve group is arranged at one end, close to the dry desulfurizing tower, of the pipeline between the TRT power generation device and the dry desulfurizing tower;
and a desulfurizing tower outlet valve group is also arranged at one end, close to the dry desulfurizing tower, between the dry desulfurizing tower and the gas outlet on-line monitoring device.
The system further comprises a first bypass valve bank, wherein the inlet end of the first bypass valve bank is communicated with the outlet end of the bag type dust collector, and the outlet end of the first bypass valve bank is communicated with the inlet end of the TRT power generation device.
The system further comprises a second bypass valve bank, wherein the inlet end of the second bypass valve bank is communicated with the outlet end of the TRT power generation device, and the outlet end of the second bypass valve bank is communicated with the inlet end of the gas user.
A gas cooling device is arranged between the TRT power generation device and the inlet valve bank of the desulfurizing tower; a coal gas heating device is arranged between the desulfurizing tower inlet valve group and the dry desulfurizing tower; the gas cooling device is communicated with the gas outlet on-line monitoring device through a pipeline, and a gas regulating valve is arranged on the pipeline between the gas cooling device and the gas outlet on-line monitoring device.
The further scheme is that the dechlorination pretreatment tower inlet valve bank, the hydrolysis conversion tower outlet valve bank, the desulfurization tower inlet valve bank and the desulfurization tower outlet valve bank are combined valves of an electric butterfly valve and an electric blind plate valve.
The further proposal is that the system at least comprises two groups of dechlorination pre-treatment towers and hydrolysis conversion towers
In a second aspect of the present invention, there is provided a method for treating a blast furnace gas source head, the method comprising the steps of:
step 1, performing dust removal treatment on blast furnace gas by a bag type dust remover to obtain gas I;
step 2, sequentially carrying out dry dechlorination pretreatment and organic sulfur hydrolysis conversion treatment on the coal gas subjected to dust removal treatment to obtain coal gas II;
step 3, carrying out dry desulfurization treatment on the coal gas II to obtain coal gas III;
and 4, enabling the coal gas III to enter a terminal combustion user through a coal gas pipe network.
In the step 1, the dust content of the coal gas I is lower than 10mg/Nm3；
In the step 2, the strength of the dechlorination pretreating agent of the dry dechlorination pretreatment is more than 50N/cm, the chlorine capacity is more than 20 percent, and the concentration of chloride ions is less than 1mg/m3(ii) a The flow velocity in the tower is less than 1 m/s; the reaction temperature is 90-200 ℃.
And a further scheme is that after the step 2 is finished, introducing the coal gas II into a TRT power generation device, and driving a generator to generate power by utilizing the terminal pressure energy and heat energy of the blast furnace top coal gas through turbine expansion.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention can implement fine desulfurization treatment at the source of the blast furnace gas, convert most organic sulfur contained in the gas at the source and remove inorganic sulfur, thereby greatly reducing the investment of independently and dispersedly arranging environmental protection devices for terminal users such as hot blast stoves and the like, saving the investment and the operating cost of environmental protection facilities and simultaneously reducing the difficulty of operation and maintenance.
(2) The invention can implement dechlorination treatment at the source of the blast furnace gas, and is provided with the gas temperature regulating device to prevent the gas temperature from being reduced to be below the dew point to generate condensed water so as to corrode subsequent pipelines and equipment.
(3) The comprehensive treatment process adopted by the invention is a dry process, and secondary pollutants such as waste water and the like generated by wet desulphurization are avoided.
(4) The invention adopts the dechlorination pretreatment tower and the hydrolysis conversion tower which are connected in series to form a group and then are arranged in parallel, and the desulfurization towers are arranged in parallel, thereby meeting the requirements that each group of systems or each desulfurization tower can independently replace the material agent and independently overhaul without influencing the operation of a front-end blast furnace and the SO outlet2Ultra-low emission requirements.
Drawings
The invention is illustrated and described only by way of example and not by way of limitation in the scope of the invention as set forth in the following drawings, in which:
FIG. 1: the invention is a schematic diagram of a system connection structure.
Detailed Description
In order to make the objects, technical solutions, design methods, and advantages of the present invention more apparent, the present invention will be further described in detail by specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, the invention provides a blast furnace gas source treatment system, which comprises a bag type dust collector 2, a gas inlet online monitoring device 3, a dechlorination pretreatment tower 5, a hydrolysis conversion tower 6, a TRT power generation device 10, a dry desulfurization tower 14, a gas outlet online monitoring device 16 and a gas user 19, wherein the bag type dust collector is communicated with a blast furnace exhaust port 1 through a pipeline in sequence; an inlet valve group 4 of the dechlorination pretreatment tower is arranged on a pipeline between the air inlet on-line monitoring device 3 and the dechlorination pretreatment tower 5; a hydrolysis conversion tower outlet valve bank 7 is arranged on a pipeline between the hydrolysis conversion tower 6 and the TRT power generation device 10; a desulfurization tower inlet valve group 12 is arranged on a pipeline between the TRT power generation device 10 and the dry desulfurization tower 14;
and a desulfurizing tower outlet valve group 15 is also arranged between the dry desulfurizing tower 14 and the gas outlet on-line monitoring device 16. The system further comprises a first bypass valve group 8, wherein the inlet end of the first bypass valve group 8 is communicated with the outlet end of the bag type dust collector 2, and the outlet end of the first bypass valve group 8 is communicated with the TRT power generation device 10. The system further comprises a second bypass valve group 18, wherein the inlet end of the second bypass valve group 18 is communicated with the TRT power generation device 10, and the outlet end of the second bypass valve group 18 is communicated with the gas user 19. A coal gas cooling device 11 is arranged between the TRT power generation device 10 and the desulfurizing tower inlet valve group 12; a gas heating device 13 is arranged between the desulfurizing tower inlet valve group 12 and the dry desulfurizing tower 14; the gas cooling device 11 is communicated with the gas outlet on-line monitoring device 16 through a pipeline, and a pipeline 17 is arranged between the gas cooling device 11 and the gas outlet on-line monitoring device 16. And the dechlorination pretreatment tower inlet valve group 4, the hydrolysis conversion tower outlet valve group 7, the desulfurization tower inlet valve group 12 and the desulfurization tower outlet valve group 15 are all combined valves of electric butterfly valves and electric blind plate valves. The system at least comprises two groups of dechlorination pretreatment towers 5 and a hydrolysis conversion tower 6;
the two groups of dechlorination pretreatment towers 5 and the hydrolysis conversion tower 6 are arranged in parallel;
the system comprises at least two groups of dry desulfurization towers 14;
the two groups of dry desulfurization towers 14 are arranged in parallel.
The gas quantity at the exhaust port 1 of the blast furnace is about 300000Nm3H, total sulfur (only sulfur element) of blast furnace gas is less than or equal to 100mg/m3The gas temperature is 90-200 ℃, and the gas pressure is 200-300 kPa; after the bag-type dust collector 2 removes dust, the dust content in the coal gas is less than or equal to 10mg/m 3; the inlet on-line detection device 3 can detect the system inlet H2S, dust, flow, pressure, temperature and other parameters, and simultaneously, the content of COS can be manually monitored; the inlet valve group 4 of the dechlorination tower comprises an electric butterfly valve capable of adjusting the gas flow entering the tower and an electric blind plate valve for cutting off the gas, when the dechlorination tower is in normal operation, the electric blind plate valve is in an open state, the blast furnace gas enters the dechlorination pretreatment tower 5 from the side part after passing through the adjusting electric valve, dechlorination pretreatment agents are filled in the dechlorination pretreatment tower, and inorganic chlorine, a small amount of hydrocarbon substances and dust in the gas are removed, so that the inorganic chlorine in the gas is reduced to 1mg/m3The reaction temperature of the dechlorination pretreatment agent is 90-200 ℃, a feed inlet is arranged at the top of the dechlorination pretreatment tower 5, a discharge outlet is arranged at the bottom of the dechlorination pretreatment tower, the adsorbed saturated waste material agent is discharged, and the working pressure of the dechlorination pretreatment tower is 200-300 kPa.
The blast furnace gas after dechlorination pretreatment is discharged from the bottom of the tower and enters a hydrolysis conversion tower 6, and organic sulfur (mainly carbonyl sulfide COS and a small amount of CS) in the blast furnace gas is treated by the hydrolysis conversion tower2) Conversion to inorganic sulfur H2S, the conversion rate is more than 90%, the reaction temperature of the hydrolysis catalytic conversion agent is 90-200 ℃, a feed inlet is arranged at the top of the hydrolysis conversion tower 6, a discharge outlet is arranged at the bottom of the tower, the waste material agent is discharged, the working pressure of the hydrolysis conversion tower is 200-300kPa, and the temperature of the coal gas after the hydrolysis conversion treatment is basically consistent with that of the inlet; from hydrolysis conversion towerThe coal gas of end discharge, process the conversion tower outlet valve valves 7 of hydrolysising, the valves contain electronic blind plate valve and electric switch type butterfly valve, and the electronic blind plate valve is installed earlier to the tower exit position, when needs shut down, starts the blind plate valve, cuts off the coal gas, when needing to overhaul the equipment and the device in butterfly valve or tower district simultaneously, also can start the electronic blind plate valve of the conversion tower outlet valve valves 7 of hydrolysising and dechlorination tower inlet valve group 4 simultaneously, cuts off the coal gas fast, improves system security.
The first bypass valve bank 8 comprises an on-off electric butterfly valve and an electric blind plate valve, when the blast furnace is in an accident state, the gas temperature exceeds the design temperature, the gas cannot enter the dechlorination pretreatment tower 5 and the hydrolysis conversion tower 6, the bypass valve bank 8 needs to be opened, and the dechlorination tower inlet valve bank 4 and the hydrolysis conversion tower outlet valve bank 7 are closed simultaneously.
The pressure reducing valve group 9 and the TRT power generation device 10 are original devices of a blast furnace gas outlet, the blast furnace gas and the TRT power generation device are arranged in parallel, usually, the blast furnace gas enters a rear-end low-pressure gas pipe network through the TRT power generation device, when the TRT power generation device needs to be stopped, the gas enters the low-pressure gas pipe network after being subjected to pressure regulation through the pressure reducing valve group 9, and at the moment, the gas temperature is still high and is higher than 90 ℃.
After the coal gas passes through the pressure reducing valve group, the temperature of the coal gas cooling device 11 is high, the coal gas cooling device 11 needs to be started, the temperature is reduced to be below 90 ℃, the subsequent flow can be entered, otherwise the subsequent desulfurization effect is influenced, and the coal gas cooling device 11 comprises a water tank, a water pump and a double-fluid atomization spray gun.
When the temperature of the coal gas passes through the TRT power generation device 10 and is generally lower than 80 ℃, the coal gas cooling device 11 does not need to be started, and the coal gas directly enters the dry-method desulfurization tower 14; when the temperature of the coal gas is lower than 45 ℃, condensed water appears in the coal gas, the condensed water can corrode a pipeline, the rear-end desulfurization effect is influenced, and meanwhile, the reaction of a rear-end desulfurizer is influenced, so that the coal gas heating device 13 needs to be started.
The dry desulfurization tower 14, the outlet coal gas of the pressure reducing valve group 9 or the TRT power generation device 10, the temperature is 45-80 ℃, the pressure is lower than 30kPa, the coal gas directly enters the desulfurization tower 14, the blast furnace coal gas enters from the lower side of the tower, and the treated clean coal gas is discharged from the bottom of the tower. In gasH2S reacts to produce elemental sulfur under the action of a desulfurizer in the desulfurizing tower 14, and the concentration of H2S at the outlet of the dry desulfurizing tower 14 is ensured to be less than or equal to 25mg/m3Or SO discharged from the outlet of gas user 192The concentration is less than 30mg/m3. The generated sulfur simple substance is adsorbed on the surface of the desulfurizer, and the desulfurizer adopts an iron-based desulfurizer, so that the waste desulfurizer after saturated adsorption can be directly transported to a sintering production line for comprehensive utilization.
Desulfurizing tower entry valves 12 and desulfurizing tower export valves 15 for adjust and turn-off coal gas, desulfurizing tower entry valves 12 contain regulation type electric butterfly valve and electronic blind plate valve double valve group, desulfurizing tower export valves 15 contain on-off type electric butterfly valve and electronic blind plate valve double valve group, the regulation type electric butterfly valve of desulfurizing tower entry valves 12
The gas quantity can be adjusted at the tower inlet according to the load of the blast furnace gas. The electric blind plate valves of the inlet valve group 12 and the outlet valve group 15 of the desulfurizing tower are used for cutting off coal gas, and when the desulfurizing tower needs to replace a material agent or overhaul, the electric blind plate valves of the inlet and the outlet can be started.
The online monitoring device 16 for the outlet of the desulfurization system is arranged on the main pipe of the outlet of the desulfurization system and can detect the outlet H of the system2S, dust, flow, pressure, temperature, etc.
The gas regulating valve 17 is used for regulating the gas quantity entering the dry desulfurization system so as to ensure that the adsorption is close to saturation at the initial stage and the later stage of filling the desulfurizer and can ensure that the outlet H of the dry desulfurization tower 14 can be saturated2S concentration is less than or equal to 25mg/m3Or SO discharged from the outlet of gas user 192The concentration is less than 30mg/m3. The phenomenon that the concentration of H2S at the outlet of the dry desulfurization tower 14 is nearly zero due to strong adsorption force of the feed agent at the initial stage of filling the desulfurizer is avoided, the service life of the feed agent can be prolonged, and the operation cost is reduced.
The second bypass valve bank 18 comprises a switch type electric butterfly valve and an electric blind plate valve, when the blast furnace is in an accident state, and the gas temperature exceeds the design temperature, the gas cannot enter the dry-method desulfurization tower 14, the bypass valve bank 18 needs to be opened, the desulfurization tower inlet valve bank 12 and the desulfurization tower outlet valve bank 15 are closed, and the gas directly enters a gas user 19.
Dechlorination preliminary treatment tower 5 and hydrolysis conversion tower 6 are the series arrangement, and single blast furnace gas corresponds three sets of dechlorination preliminary treatment towers 5 and hydrolysis conversion tower 6, need to set up three chlorine preliminary treatment towers 5 and three hydrolysis conversion towers 6 promptly, guarantee that every dechlorination preliminary treatment tower 5 of group and hydrolysis conversion tower 6 can the isolated operation, and can handle the tolerance that is higher than the coal gas design value for the short time, in order to make things convenient for other dechlorination preliminary treatment towers 5 and hydrolysis conversion tower 6's the maintenance and the change of feed additive, and need not to stop transporting the blast furnace, do not influence blast furnace main system production.
The dry-method desulfurization tower 14 is characterized in that a single blast furnace is provided with three dry-method desulfurization towers 14 which are arranged in parallel, and outlet coal gas of the pressure reducing valve group 9 or the TRT power generation device 10 simultaneously enters the three dry-method desulfurization towers 14, so that each dry-method desulfurization tower 14 can operate independently, and gas quantity higher than the designed value of the coal gas can be processed in a short time, so that the overhaul and the material agent replacement of the other two dry-method desulfurization towers 14 are facilitated, the blast furnace does not need to be stopped, and the production of a main system of the blast furnace is not influenced.
Based on the structure of the system, the blast furnace gas source treatment method comprises the following steps: the blast furnace gas dedusted from the cloth bag is firstly subjected to pretreatment such as removal of inorganic chlorine, a small amount of hydrocarbons, dust and the like in the gas by a dry dechlorination pretreatment system, so that the subsequent hydrolysis catalytic conversion agent is prevented from influencing the conversion efficiency due to the deactivation of chloride ions and the like contained in the gas; the coal gas after the dry dechlorination pretreatment enters a series-connected hydrolysis conversion system, and organic sulfur (mainly carbonyl sulfur and a small amount of CS) in the coal gas enters a hydrolysis conversion system at a certain temperature2) Under the action of catalytic converter, the water carried in coal gas is converted into inorganic sulfur (mainly H)2S). The blast furnace gas after the front-end dry dechlorination pretreatment and the hydrolysis conversion treatment is returned to the TRT power generation device or the pressure reducing valve bank through the gas pipe network, the blast furnace gas passing through the TRT power generation device or the pressure reducing valve bank is introduced into the rear-end dry desulphurization system, and inorganic sulfur in the gas is subjected to adsorption conversion reaction with an iron-based desulfurizer under the premise of certain oxygen content at a certain temperature, so that a sulfur simple substance is finally generated. Removal of inorganic sulfur (mainly H)2S) blast furnace gas is connected into a gas main pipe network and sent to a terminalThe gas user burns. Because the source has carried out comprehensive treatment on organic sulfur and inorganic sulfur, SO after combustion2The emission concentration can meet the requirement of ultra-low emission. The continuity and the stability of the operation are comprehensively considered, the front-end dry dechlorination pretreatment tower and the hydrolysis conversion tower are connected in series to form a group, meanwhile, a plurality of groups of dry dechlorination pretreatment towers and the hydrolysis conversion tower are connected in parallel, the rear-end dry desulfurization tower is connected in parallel, the independent operation and the independent maintenance can be formed, the modes of standby are mutually realized, and the operation of the blast furnace main body is not influenced.
In the comprehensive treatment process of the blast furnace gas source dry dechlorination and desulfurization, the dry dechlorination pretreatment system is used for removing inorganic chlorine, a small amount of hydrocarbons and dust substances in the blast furnace gas, so that the impurities are prevented from influencing the efficiency of a hydrolysis catalytic conversion agent in a subsequent hydrolysis conversion system. The dry dechlorination pretreatment system comprises a dechlorination pretreatment tower, valve banks such as a butterfly valve, a blind plate valve and the like are arranged at the inlet of a tower body, coal gas enters the dechlorination pretreatment tower from bottom to top, and the reacted coal gas is discharged from a gas outlet at the bottom of the tower. In the comprehensive treatment process for the dry dechlorination and desulfurization from the blast furnace gas source, the dechlorination pretreatment tower is a main reaction device, and the tower comprises a dechlorination pretreatment agent layer, an auxiliary facility such as an agent supporting plate and a gas uniform distribution distributor, a feeding port of a tower body feeding agent, a discharging port of a discharging agent, a gas inlet and a gas outlet of gas, a gas discharging port, a water outlet and the like. The dechlorination pretreating agent is a main reaction body for dechlorination, the material agent needs to have certain strength, the strength needs to be more than 50N/cm, the pulverization phenomenon of the material agent in the presence of condensed water in blast furnace gas is avoided, the chlorine capacity of the material agent is more than 20 percent, and therefore when the gas enters a subsequent hydrolysis conversion tower, the concentration of chlorine ions is lower than 1mg/m3. The auxiliary facilities in the tower can ensure that the coal gas is fully contacted with the dechlorination pretreating agent, the flow field is optimized, the flow rate of the coal gas passing through the material layer is reduced, the flow rate in the tower needs to be lower than 1m/s, the coal gas is ensured to be fully contacted with the dechlorination pretreating agent, and the dechlorination and pretreatment effects are improved. The reaction temperature of the dechlorination pretreating agent cannot be lower than 90 ℃, the general requirement is 90-200 ℃, and the temperature of blast furnace gas passing through the bag-type dust collector just meets the requirement of the temperature rangeSince the outlet pressure of blast furnace gas is generally 190-300kPa, belonging to a high-pressure system, the dechlorination pretreatment tower is designed according to a pressure vessel.
In the comprehensive treatment process for the dry dechlorination and desulfurization of the blast furnace gas source, the valve bank comprises a gas butterfly valve with a regulating function and a gas blind plate valve with a turn-off function, and the valve bank is arranged at an inlet of the dechlorination pretreatment tower. The gas butterfly valve with the adjusting function in the valve group is used for adjusting the gas quantity entering the tower, the adjusting range is 50-100%, and the fluctuation of the front-end blast furnace gas quantity can be met; the gas blind plate valve with the turn-off function in the valve bank can directly cut off gas when the dechlorination pretreatment tower needs to be overhauled or the filler needs to be replaced, so that the butterfly valve and the blind plate valve are arranged in sequence from the direction of a gas inlet, and the safety of the system can be improved due to the arrangement.
In the comprehensive treatment process for the dechlorination and the desulfurization of the blast furnace gas source head by the dry method, the hydrolysis conversion system is connected with the dry dechlorination pretreatment system in series. The hydrolysis conversion system is used for hydrolyzing and converting organic sulfur in blast furnace gas into inorganic sulfur. The main components of the organic sulfur of blast furnace gas are carbonyl sulfide (COS) and a trace amount of CS2Organic sulfur reacts with water vapor molecules in the coal gas at a proper temperature under the action of a hydrolysis catalyst to be converted into inorganic sulfur (hydrogen sulfide). The hydrolysis conversion system comprises a hydrolysis conversion tower, and valve banks such as a butterfly valve, a blind plate valve and the like are arranged at the outlet of the tower body. And the coal gas enters the hydrolysis conversion tower from the bottom to the top from the gas outlet of the dry dechlorination pretreatment tower, and the reacted coal gas is discharged from the gas outlet at the bottom of the tower and is connected to a TRT power generation device or a pressure reducing valve bank.
In the comprehensive treatment process for the dechlorination and the desulfurization of the blast furnace gas source by the dry method, the hydrolysis conversion tower is a main reaction device, and a hydrolysis catalytic conversion material layer, a material supporting plate, a material sleeve, a coal gas uniform distributor and other auxiliary facilities are arranged in the tower, and a feeding port of a material loading agent of the tower body, a discharging port of the material loading agent, an air inlet and an air outlet of the coal gas, a coal gas discharging port, a tower body water outlet and the like are arranged in the tower. The hydrolysis catalytic conversion material agent is the main body of the conversion reaction, the suitable reaction temperature of the material agent is 90-200 ℃, the conversion rate of organic sulfur can reach more than 90 percent, and the material agent can convert organic sulfur in blast furnace gasConversion of most of the organic sulfur to inorganic sulfur (mainly H)2S)。
In the comprehensive treatment process for the dry dechlorination and desulfurization of the blast furnace gas source, the outlet valve bank comprises a gas butterfly valve with a switching function and a gas blind plate valve with a switching-off function, the blind plate valves and the butterfly valve are arranged at the outlet of the hydrolysis conversion tower in sequence, and when the hydrolysis conversion tower needs to be overhauled or a material agent needs to be replaced, the gas can be cut off by the blind plate valves, so that the safety of the system is improved.
In the comprehensive treatment process for the dechlorination and the desulfurization by the blast furnace gas source dry method, the TRT power generation device is an original device of a blast furnace gas system, and the TRT power generation device is used for driving a power generator to generate power by utilizing the pressure energy and the heat energy of the blast furnace top gas terminal through turbine expansion work, and can recover about 30% of blast energy of the blast furnace as an energy-saving device. Therefore, the front part of the TRT power generation device is a high-pressure system, the temperature of the coal gas is higher, the rear part of the TRT power generation device is a low-pressure system, and the temperature of the coal gas is reduced.
In the comprehensive treatment process for the dry dechlorination and desulfurization of the blast furnace gas source, the pressure reducing valve bank is an original device of a blast furnace gas system and is arranged in parallel with the TRT power generation device. When the TRT power generation device is in emergency shutdown, the pressure of the gas needs to be adjusted and released through the pressure reducing valve bank, so that the top pressure of the blast furnace is ensured not to generate large fluctuation, and meanwhile, the low-pressure gas is ensured to be supplied to other users such as a terminal hot blast stove and the like. When the pressure of the coal gas is adjusted by the pressure reducing valve bank, the rear end of the valve bank is still a low-pressure system, but the temperature of the coal gas is higher.
In the comprehensive treatment process of blast furnace gas source dry dechlorination and desulfurization, the dry desulfurization system is used for removing inorganic sulfur (mainly H) in the gas2S) and converted to elemental sulphur. The main sulfur-containing substances of the coal gas after the front-end dechlorination pretreatment and the hydrolysis conversion treatment are H2S, after passing through a TRT power generation device or a pressure reducing valve group, enters a low-pressure gas pipe network, the pressure is generally lower than 30kPa, and the S is introduced into a dry desulfurization system again to carry out H2S is removed, and finally, an outlet H is realized2The content of S is less than 25mg/Nm3Or SO discharged after combustion of gas users such as terminal hot blast stove and the like2The content is less than 30mg/Nm3. The dry desulfurization system comprises a dry desulfurization tower, a gas temperature regulating device, an oxygen supplementing device, a gas regulating device, valve banks such as a butterfly valve, a blind plate valve and the like, wherein the valve banks are arranged at the inlet and the outlet of the tower body. The coal gas enters the hydrolysis conversion tower from the bottom to the top from the gas outlet of the dry dechlorination pretreatment tower, and the reacted clean coal gas is discharged from the gas outlet at the bottom of the tower and is connected back to the coal gas low-pressure pipe network.
In the comprehensive treatment process of the blast furnace gas source dry dechlorination and desulfurization, the dry desulfurization tower is a main reaction device, and the tower comprises a desulfurizing agent, auxiliary facilities such as a material agent supporting plate, a material agent sleeve barrel and a gas uniform distributor, a feeding port of a tower body feeding agent, a discharging port of a discharging agent, a gas inlet and a gas outlet, a gas discharging port, a tower body water outlet and the like. The desulfurizer is a main body of reaction, mainly is an iron-based substrate desulfurizer, the proper reaction temperature of the feed is 40-90 ℃, and the sulfur capacity of the feed is more than 20%. In the conversion reaction process, certain oxygen needs to be supplemented to ensure that the oxygen content in the coal gas reaches certain concentration and H in the blast furnace gas2S is converted and reacted under the action of the desulfurizer to generate a sulfur simple substance which is attached to the desulfurizer, thereby achieving the effect of blast furnace gas desulfurization.
In the comprehensive treatment process for the dechlorination and the desulfurization of the blast furnace gas source by the dry method, the temperature regulating device of the gas is used for regulating the temperature of the gas and comprises a temperature reducing device and a heating device. When the TRT power generation device is in emergency shutdown, the blast furnace gas needs to be subjected to pressure regulation through a pressure reducing valve bank, the temperature of the gas at an outlet is generally higher than 90 ℃, the reaction temperature of a desulfurizer is not met, and a temperature reducing device is arranged at an inlet of a desulfurizing tower to reduce the temperature of the gas to be lower than 90 ℃. The temperature reducing device comprises atomizing and water spraying devices such as a two-fluid atomizing spray gun and the like. When the temperature of the gas after the TRT power generation device is lower, condensed water can be separated out from the gas, and the condensed water has certain influence on the desulfurizer. The heating device is arranged at the inlet of the desulfurizing tower to increase the temperature of the coal gas to be above the dew point of the coal gas, and the heating device is suitable for the reaction of the desulfurizing agent. The device is one or a combination of a steam heat exchanger, a gas-water heat exchanger and a gas-gas heat exchanger.
The blast furnace gas source dry dechlorination and desulfurization healdIn the combined treatment process, the coal gas oxygen supplementing device is used for H in coal gas2When S reacts with desulfurizer, oxygen with a certain concentration is provided, which is more beneficial to H2S is converted into elemental sulfur under the action of a desulfurizing agent, and the produced elemental sulfur can be recycled. The oxygen supplementing device mainly comprises an oxygen conveying pipeline, an adjusting valve group, a thermal control instrument for temperature, pressure and the like, interlocking control feedback and the like.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A blast furnace gas source treatment system is characterized by comprising a bag type dust collector (2), an air inlet online monitoring device (3), a dechlorination pretreatment tower (5), a hydrolysis conversion tower (6), a TRT power generation device (10), a dry desulfurization tower (14), an air outlet online monitoring device (16) and a gas user (19), wherein the bag type dust collector is communicated with a blast furnace exhaust port (1) through a pipeline in sequence;
an inlet valve bank (4) of the dechlorination pretreatment tower is arranged at one end, close to the dechlorination pretreatment tower (5), of a pipeline between the air inlet online monitoring device (3) and the dechlorination pretreatment tower (5);
a hydrolysis conversion tower outlet valve group (7) is arranged at one end, close to the hydrolysis conversion tower (6), of the pipeline between the hydrolysis conversion tower (6) and the TRT power generation device (10);
a desulfurizing tower inlet valve group (12) is arranged at one end, close to the dry desulfurizing tower (14), of the pipeline between the TRT power generation device (10) and the dry desulfurizing tower (14);
and a desulfurizing tower outlet valve group (15) is also arranged at one end, close to the dry desulfurizing tower (14), between the dry desulfurizing tower (14) and the gas outlet on-line monitoring device (16).
2. The blast furnace gas source head abatement system of claim 1, further comprising a first bypass valve block (8), an inlet end of the first bypass valve block (8) communicating with an outlet end of the baghouse (2), an outlet end of the first bypass valve block (8) communicating with an inlet end of the TRT power plant (10).
3. The blast furnace gas source head abatement system of claim 1, further comprising a second bypass valve block (18), an inlet end of the second bypass valve block (18) being in communication with an outlet end of the TRT power plant (10), an outlet end of the second bypass valve block (18) being in communication with an inlet end of the gas user (19).
4. The blast furnace gas source head abatement system of claim 1, wherein a gas temperature reduction device (11) is provided between the TRT power generation plant (10) and the desulfurization tower inlet valve block (12); a coal gas heating device (13) is arranged between the desulfurizing tower inlet valve group (12) and the dry desulfurizing tower (14); the gas cooling device (11) is communicated with the gas outlet on-line monitoring device (16) through a pipeline, and a gas regulating valve (17) is arranged on the pipeline between the gas cooling device (11) and the gas outlet on-line monitoring device (16).
5. The blast furnace gas source head treatment system according to claim 4, wherein the dechlorination pretreatment tower inlet valve group (4), the hydrolysis conversion tower outlet valve group (7), the desulfurization tower inlet valve group (12) and the desulfurization tower outlet valve group (15) are all combined valves of an electric butterfly valve and an electric blind plate valve.
6. The blast furnace gas source head abatement system of claim 4, wherein the system comprises at least two sets of a dechlorination pre-treatment column (5) and a hydrolysis conversion column (6);
the two groups of dechlorination pretreatment towers (5) and the hydrolysis conversion tower (6) are arranged in parallel;
the system comprises at least two groups of dry desulfurization towers (14);
the two groups of dry-method desulfurization towers (14) are arranged in parallel.
7. A method of treating a blast furnace gas source head, wherein the method employs the system of any one of claims 1 to 5.
8. The blast furnace gas source head abatement method of claim 6, comprising the steps of:
step 1, performing dust removal treatment on blast furnace gas by a bag type dust remover to obtain gas I;
step 2, sequentially carrying out dry dechlorination pretreatment and organic sulfur hydrolysis conversion treatment on the coal gas subjected to dust removal treatment to obtain coal gas II;
step 3, carrying out dry desulfurization treatment on the coal gas II to obtain coal gas III;
and 4, enabling the coal gas III to enter a terminal combustion user through a coal gas pipe network.
9. The blast furnace gas source head treatment method according to claim 7,
in the step 1, the dust content of the coal gas I is lower than 10mg/Nm 3;
in the step 2, the strength of the dechlorination pretreating agent of the dry dechlorination pretreatment is more than 50N/cm, the chlorine capacity is more than 20 percent, and the concentration of chloride ions is less than 1mg/m 3; the flow velocity in the tower is less than 1 m/s; the reaction temperature is 90-200 ℃.
10. The method for treating the blast furnace gas source head according to claim 8, wherein after the step 2 is finished, the gas II is introduced into a TRT power generation device, and a power generator is driven to generate power by turbine expansion by utilizing terminal pressure energy and heat energy of the blast furnace top gas.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116144408A (en) * | 2023-03-17 | 2023-05-23 | 北京铝能清新环境技术有限公司 | Hierarchical purification and fine desulfurization system and method for blast furnace gas after dry dedusting |
| CN116445672A (en) * | 2023-03-17 | 2023-07-18 | 北京铝能清新环境技术有限公司 | Blast furnace gas fine desulfurization dust-blocking filtering ash-cleaning system and use method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5843219A (en) * | 1981-09-07 | 1983-03-12 | Hitachi Ltd | Dry type waste gas desulfurization method and its apparatus |
| CN102181871A (en) * | 2011-04-01 | 2011-09-14 | 北京首钢国际工程技术有限公司 | Heating and corrosion-prevention method for gas pipeline of hot blast stove |
| CN111534335A (en) * | 2020-03-25 | 2020-08-14 | 南京中电环保科技有限公司 | Blast furnace gas hydrolysis and dry-process fine desulfurization treatment system and method |
| CN111944563A (en) * | 2020-09-15 | 2020-11-17 | 中冶华天工程技术有限公司 | Novel blast furnace gas desulfurization system |
| CN112593034A (en) * | 2020-04-30 | 2021-04-02 | 上海大学 | Dry-method cooperative deacidification system and method for blast furnace clean gas |
-
2021
- 2021-11-11 CN CN202111335470.XA patent/CN114181742A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5843219A (en) * | 1981-09-07 | 1983-03-12 | Hitachi Ltd | Dry type waste gas desulfurization method and its apparatus |
| CN102181871A (en) * | 2011-04-01 | 2011-09-14 | 北京首钢国际工程技术有限公司 | Heating and corrosion-prevention method for gas pipeline of hot blast stove |
| CN111534335A (en) * | 2020-03-25 | 2020-08-14 | 南京中电环保科技有限公司 | Blast furnace gas hydrolysis and dry-process fine desulfurization treatment system and method |
| CN112593034A (en) * | 2020-04-30 | 2021-04-02 | 上海大学 | Dry-method cooperative deacidification system and method for blast furnace clean gas |
| CN111944563A (en) * | 2020-09-15 | 2020-11-17 | 中冶华天工程技术有限公司 | Novel blast furnace gas desulfurization system |
Non-Patent Citations (3)
| Title |
|---|
| 朱廷钰等: "《烧结烟气排放控制技术及工程应用》", 31 January 2015 * |
| 李凯: "《化工行业大气污染控制》", 31 January 2016 * |
| 王星等: "《分类有机垃圾的终端厌氧处理技术》", 31 January 2018 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116144408A (en) * | 2023-03-17 | 2023-05-23 | 北京铝能清新环境技术有限公司 | Hierarchical purification and fine desulfurization system and method for blast furnace gas after dry dedusting |
| CN116445672A (en) * | 2023-03-17 | 2023-07-18 | 北京铝能清新环境技术有限公司 | Blast furnace gas fine desulfurization dust-blocking filtering ash-cleaning system and use method thereof |
| CN116445672B (en) * | 2023-03-17 | 2024-01-05 | 北京铝能清新环境技术有限公司 | Blast furnace gas fine desulfurization dust-blocking filtering ash-cleaning system and use method thereof |
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