CN114307528B - System and method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching scattered gas - Google Patents
System and method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching scattered gas Download PDFInfo
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Abstract
The invention belongs to the technical field of coking flue gas treatment, and particularly relates to a system and a method for preparing concentrated sulfuric acid by utilizing coke oven flue gas and dry quenching scattered gas, wherein the system comprises a preprocessor, an air inlet end of which is communicated with air outlet ends of a coke oven and a dry quenching furnace; the reactor A comprises an adsorption layer, an SCR denitration catalyst bed layer and a sulfur dioxide conversion catalyst bed layer from top to bottom; the reactor B is internally provided with a sulfur dioxide conversion catalyst; the top of the condensing cooling absorber is provided with a spraying device which is provided with a desalted water inlet and a sulfuric acid circulating spraying inlet; the bottom of the condensation cooler is communicated with a concentrated sulfuric acid collecting tank, a booster pump is arranged between the concentrated sulfuric acid collecting tank and the spraying device, liquid in the concentrated sulfuric acid collecting tank is partially conveyed into the spraying device for spraying through the booster pump, and one part of the liquid is conveyed to a concentrated sulfuric acid storage tank of a tank area for sale or is conveyed to an ammonium sulfate working section using unit of a factory area. The invention prepares concentrated sulfuric acid by using coke oven flue gas and dry quenching scattered gas, reduces flue gas emission and improves enterprise profit.
Description
Technical Field
The invention belongs to the technical field of coking flue gas treatment, and particularly relates to a system and a method for preparing concentrated sulfuric acid by utilizing coke oven flue gas and dry quenching scattered gas.
Background
The coking industry pollutes the atmosphere, wherein the main pollution sources are coke oven flue gas and dry quenching scattered gas, about 60 percent of SO 2 Is derived from coke oven flue gas and dry quenching gas emission, SO 2 The environment-friendly acid gas is colorless, has strong pungent smell, is one of main pollutants in the atmosphere, is discharged into the atmosphere to be oxidized into sulfuric acid mist or sulfate aerosol, causes acid rain, pollutes the environment, has great influence on human health and an ecological system, and belongs to one of 3 types of cancerogens published by the international cancer research institute of the world health organization. SO of coke oven flue gas and dry quenching gas release 2 The coke is volatilized in the coke oven mainly from the combustion of inorganic sulfur and organic sulfur contained in the return gas, and then the sulfur contained in the raw gas in the coking chamber is leaked in a series manner after being leaked in a series manner to a combustion chamber, so that the coke is generated. National publication of emission Standard for pollutants for coking chemistry, GB16171-2012, national publication of Coke chemistry Industrial pollutant discharge Standard, 6, 27, 2012, requires an existing enterprise from 10, 1, 2012SO (sulfur dioxide) discharged from machine coke and semicoke furnace chimney in atmospheric pollutant discharge limit value executed by industry and new enterprises 2 ≤50mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the SO discharged from chimney of heat recovery coke oven 2 ≤100mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the SO discharged by dry quenching 2 ≤100mg/m 3 . According to the requirements of national environmental protection work, in the areas where the national development density is higher, the environmental bearing capacity begins to weaken, or the atmospheric environment capacity is smaller, the ecological environment is fragile, serious atmospheric environmental pollution problem is easy to occur and special protection measures are needed, the pollutant discharge behavior of enterprises should be strictly controlled, and SO discharged by the enterprise coke and semicoke furnace chimney in the areas is required to be strictly controlled 2 ≤30mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the SO discharged from chimney of heat recovery coke oven 2 ≤30mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the SO discharged by dry quenching 2 ≤30mg/m 3 . But the flue gas SO of the coke oven 2 The content is the same as other pollution treatments in the treatment of coke oven flue gas and dry quenching scattered gas, and is a system engineering.
The existing coke oven flue gas and dry quenching gas emission treatment technology is divided into two types, namely dry desulfurization and wet desulfurization, as shown in figure 1, wherein the dry desulfurization adopts a sodium bicarbonate method for desulfurization, and the dry quenching gas emission generated by a coke oven 1 and a dry quenching gas emission generated by a dry quenching furnace 2 passes through an SCR denitration reactor c (an ammonia water supply system d), a waste heat boiler f and an SDS reactor g (NaHCO) 3 After being treated by a supply system e) and a bag-type dust remover h, the treated dust is discharged through a chimney 10 under the pressurizing action of a system induced draft fan i, the process has high investment cost and high operation cost, sodium bicarbonate needs to be purchased, secondary pollution is caused to the environment, and NaHCO is generated in the desulfurization process 3 And SO 2 Sodium sulfite NaSO is generated 3 Sodium sulfate NaSO 4 Belongs to solid dangerous waste and is difficult to treat. As shown in FIG. 2, wet desulfurization is carried out by circularly spraying 20% concentrated ammonia water and SO in a desulfurizing tower 2 Reaction to produce ammonium bisulfate NH 4 HSO 4 And ammonium sulfate (NH) 4 ) 2 SO 4 The flue gas of the coke oven 1 generated by the coke oven and the dry quenching scattered gas generated by the dry quenching oven 2 are treated by an SCR denitration reactor c (ammonia water supply system d), a waste heat boiler f, a cooling water spraying and cooling device b and an ammonia desulfurization tower a, and the process equipmentThe corrosion and the blockage are serious, the desulfurization tower is required to stop repairing welding leakage points and clean spray heads and trays on average every month, ammonia can escape if the spraying amount of ammonia water is not well controlled, and the discharged flue gas contains more than 8ppm of ammonia, so that secondary pollution is caused to the environment.
SO how to simply, efficiently and environmentally treat the flue gas of the coke oven and the discharged gas SO of the dry quenching 2 Further research is needed.
Disclosure of Invention
In order to solve the technical problems, the invention provides a system and a method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas, wherein the coke oven flue gas and the dry quenching exhaust gas SO 2 The concentrated sulfuric acid preparing technology is a revolutionary technology innovation in the coke oven flue waste gas treatment industry, has the advantages of energy conservation, environmental protection and waste material changing, belongs to the technical field of clean and environmental protection production and circular economy, opens up a production process device which is more energy-saving, more environmental protection, cheaper, simpler and safer, and has good optimizing effect on various indexes of the coke oven.
The invention is realized by the following technical scheme.
A first object of the present invention is to provide a system for preparing concentrated sulfuric acid using coke oven flue gas and dry quenching blow-off gas, comprising:
the air inlet end of the preprocessor is communicated with the air outlet ends of the coke oven and the dry quenching furnace;
the reactor A sequentially comprises an adsorption layer positioned at the top, an SCR denitration catalyst bed at the middle and a sulfur dioxide conversion catalyst bed at the bottom along the flow direction of the flue gas, and the flue gas treated by the preprocessor is pressurized by an induced draft fan and is sent into the adsorption layer;
the reactor B is internally provided with a sulfur dioxide conversion catalyst;
a condensation cooling absorber which is communicated with the outlet end of the reactor B, wherein a cold air inlet and a hot air outlet are arranged on the condensation cooling absorber, and the cold air inlet is positioned below the hot air outlet; the top in the condensation cooling absorber is provided with a spraying device, and the spraying device is provided with a desalted water inlet and sulfuric acid circulation sprayingThe sprinkling inlet is switched by a valve, demineralized water is adopted to spray when the operation is just started, and after sulfuric acid is arranged in the concentrated sulfuric acid collecting tank, the sulfuric acid is adopted to circularly spray and absorb SO generated by the treatment of the reactor B 3 The method comprises the steps of carrying out a first treatment on the surface of the The bottom of the condensation cooler is communicated with a concentrated sulfuric acid collecting tank, a pressurizing pump is arranged between the concentrated sulfuric acid collecting tank and the spraying device, one part of liquid in the concentrated sulfuric acid collecting tank is conveyed to the spraying device for circulating spraying through a sulfuric acid circulating spraying inlet by the pressurizing pump, and the other part of liquid is delivered to a tank area concentrated sulfuric acid storage tank for sale or to a plant area ammonium sulfate working section using unit.
Preferably, the preprocessor is a ceramic fiber filter, the number of the preprocessors is 2, and the single processing amount is 450000Nm 3 And/h, the working temperature is 180-350 ℃.
Preferably, after the flue gas exhausted from the gas outlet ends of the coke oven and the dry quenching furnace are mixed, the temperature of the flue gas entering the preprocessor is 180-260 ℃, the catalyst adopted in the reactor A is a low-temperature catalyst or a medium-temperature catalyst, the working temperature of the low-temperature catalyst is 180-220 ℃, the working temperature of the medium-temperature catalyst is 250-300 ℃, and when the temperature is lower than 250 ℃, the flue gas is heated by a heating furnace.
Preferably, the air quantity of the induced draft fan is 950000Nm 3 And/h, the suction force in front of the machine is 4-5KPa, the highest pressure behind the machine is 10KPa, the fan impeller is an aluminum explosion-proof impeller, the fan matched motor is of EX explosion-proof grade, and the energy consumption device is above grade II, so that the machine is safe and energy-saving.
Preferably, the adsorption layer in the reactor a is an activated carbon adsorption layer.
Preferably, a demineralized water cooler is further arranged in the reactor B, and the flue gas treated by the sulfur dioxide conversion catalyst in the reactor B enters the condensation cooling absorber after being cooled by the demineralized water cooler.
Preferably, a heat exchanger is further arranged between the concentrated sulfuric acid collecting tank and the spraying device.
Preferably, a plurality of condensing pipes with two open ends are vertically distributed in the condensing cooler.
Preferably, the absorber is cooled by the condensationThe cleaned flue gas is discharged through a chimney, and SO in the flue gas 2 The content is less than or equal to 15mg/m 3 . In addition, in order to prevent unexpected events such as power failure and the like, the emission of smoke is ensured, the smoke emitted by the coke oven and the dry quenching scattered gas emitted by the dry quenching furnace can be directly emitted to a chimney, the process is controlled by a valve between the coke oven and the dry quenching furnace and the chimney, and the valve is closed and opened in emergency during normal production.
A second object of the present invention is to provide a method for preparing sulfuric acid using coke oven flue gas and dry quenching blow-off gas, using the above system, comprising the steps of:
s1, respectively mixing coke oven flue gas pumped from a coke oven and a dry quenching furnace with dry quenching scattered gas, and entering a preprocessor to remove dust and capture coke oil mist;
s2, pressurizing the mixed gas pretreated by the S1 by a draught fan, introducing the mixed gas into the reactor A for dedusting again, and carrying out NO on the mixed gas under the action of a catalyst x Conversion to N 2 ，SO 2 Conversion to SO 3 ；
S3, introducing the mixed gas converted by the S2 into a B reactor, wherein unconverted SO is contained in the mixed gas 2 Further conversion to SO 3 Then, the flue gas containing sulfur trioxide introduced by the reactor B reacts with the desalted water to produce sulfurous acid, the sulfurous acid flows into a concentrated sulfuric acid collecting tank at the bottom from top to bottom along the inner wall of a glass condensing pipe inside the condensation cooling absorber, at the moment, the valve of the desalted water inlet is closed, the valve of the sulfuric acid circulation spraying inlet is opened, the sulfurous acid is pressurized by a pressurizing pump and is sent to a spraying device at the top of the condensation cooling absorber through the sulfuric acid circulation spraying inlet for circulation spraying, the sprayed sulfurous acid generates concentrated sulfuric acid with the concentration of 93% or 98% under the action of sulfur trioxide and oxygen in the continuously introduced flue gas, and the generated concentrated sulfuric acid is sold outside a concentrated sulfuric acid storage tank in a tank area or is sent to an ammonium sulfate section using unit in a factory through a pressurizing pump.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention takes coke oven flue gas containing sulfur dioxide and dry quenching gas as raw materials, firstly mixes the gases, then removes impurities (dust removal and tar mist), and then converts the mixed gases (NO) x Conversion to N 2 ，SO 2 Conversion to SO 3 ) Under the action of moisture, the converted gas is used for preparing sulfuric acid, the prepared sulfuric acid is used by a coking plant, the outsourcing amount of the sulfuric acid is reduced, the production cost of the coking plant is reduced, and on the other hand, the SO of the exhaust gas is reduced 2 The content of the waste gas reaches the standard, so that the waste gas does not pollute the environment;
(2) The novel process for treating the coke oven flue gas and the dry quenching gas emissions solves the defects caused by the existing dry desulfurization and wet desulfurization, and the method is used for treating SO in the coke oven flue gas and the dry quenching gas emissions 2 The method changes waste into valuables, produces concentrated sulfuric acid for self-use or sale, is green and environment-friendly, can create benefits, belongs to the technical field of clean and environment-friendly production and circular economy, opens up a production process device which is more energy-saving, environment-friendly, cheaper, simpler and safer, and has good optimization effect on various indexes of a coke oven and a dry quenching oven;
(3) The invention has simple process flow, low investment cost, small occupied area, no need of continuously purchasing raw materials in the production process, low operation cost, no other wastes and no desulfurization ash, is more energy-saving and environment-friendly, has one-time investment, benefits for life, and has simple operation, high safety coefficient and high SO consumption 2 The produced concentrated sulfuric acid has better quality than the concentrated sulfuric acid produced by pyrite, larger market demand and large profit margin.
Drawings
FIG. 1 is a process flow diagram of a prior art dry desulfurization process;
FIG. 2 is a process flow diagram of a prior art wet desulfurization process;
FIG. 3 is a system diagram of the invention for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching blow-off gas;
reference numerals illustrate:
a. ammonia desulfurization tower, b cooling water spraying and cooling device, c and SCR denitration deviceReactor, d ammonia water supply system, e and NaHCO 3 The system comprises a supply system, a waste heat boiler, g and SDS reactors, h and a bag-type dust remover, i and a system induced draft fan;
1. coke oven, 2, dry quenching furnace, 3, preprocessor, 31, induced draft fan, 4, A reactor, 41, adsorption layer, 42, SCR denitration catalyst bed, 43, sulfur dioxide conversion catalyst bed, 5, B reactor, 51, sulfur dioxide conversion catalyst, 52, demineralized water cooler, 6, condensing and cooling absorber, 61, cold air inlet, 611, air filter, 612, cooling fan, 62, hot air outlet, 63, sprinkler, 631, demineralized water inlet, 632, sulfuric acid circulation spraying inlet, 7, concentrated sulfuric acid collecting tank, 8, booster pump, 9, heat exchanger, 10, chimney.
Detailed Description
In order that those skilled in the art will better understand the technical solution of the present invention, the present invention will be further described with reference to the specific examples and the accompanying drawings, but the examples are not intended to be limiting. The experimental methods and the detection methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.
A system for preparing concentrated sulfuric acid from coke oven flue gas and dry quenching blow-off gas, as shown in fig. 3, comprising:
the air inlet end of the preprocessor 3 is communicated with the air outlet ends of the coke oven 1 and the dry quenching furnace 2;
the reactor A4 sequentially comprises an adsorption layer 41 positioned at the top, an SCR denitration catalyst bed 42 positioned at the middle and a sulfur dioxide conversion catalyst bed 43 positioned at the bottom along the flow direction of the flue gas, and the flue gas treated by the preprocessor 3 is conveyed to the adsorption layer 41 by pressurizing through a draught fan 31 for dedusting again;
a sulfur dioxide conversion catalyst 51 is arranged in the reactor 5;
a condensation cooling absorber 6 which is communicated with the outlet end of the B reactor 5, wherein a cold air inlet 61 and a hot air outlet 62 are arranged on the condensation cooling absorber 6, and the cold air inlet 61 is positioned below the hot air outlet 62; a spraying device 63 is arranged at the inner top of the condensation cooling absorber 6, and a desalted water inlet 631 and a sulfuric acid circulation spraying inlet 632 are arranged on the spraying device 63; the bottom of the condensation cooler 6 is communicated with the concentrated sulfuric acid collecting tank 7, a booster pump 8 is arranged between the concentrated sulfuric acid collecting tank 7 and the spraying device 63, the booster pump 8 conveys one part of liquid in the concentrated sulfuric acid collecting tank 7 to the spraying device 63 for spraying through a sulfuric acid circulation spraying inlet 632, and the other part of liquid is delivered to a tank area concentrated sulfuric acid storage tank for sale or to a plant area ammonium sulfate working section using unit.
The pretreatment device 3 is a ceramic fiber filter, the number of the pretreatment devices is 2, and the single treatment capacity is 450000Nm 3 And/h, the working temperature is 180-350 ℃. After the flue gas exhausted from the gas outlet ends of the coke oven 1 and the dry quenching furnace 2 are mixed, the temperature of the flue gas entering the preprocessor 3 is 180-260 ℃, the catalyst adopted in the reactor A4 is a low-temperature catalyst or a medium-temperature catalyst, the working temperature of the low-temperature catalyst is 180-220 ℃, the working temperature of the medium-temperature catalyst is 250-300 ℃, and when the temperature is lower than 250 ℃, the flue gas is heated by adopting a heating furnace. The flue gas treated by the preprocessor 3 is pressurized and sent into the A reactor 4 by a draught fan 31, and the air quantity of the draught fan 31 is 950000Nm 3 And/h, the suction force before the machine is 4-5KPa, and the highest pressure after the machine is 10KPa. The adsorption layer 41 in the a reactor 4 is an activated carbon adsorption layer. And a desalting water cooler 52 is also arranged in the reactor B5, and the flue gas treated by the sulfur dioxide conversion catalyst 51 enters the condensation cooling absorber 6 after being cooled by the desalting water cooler 52. A heat exchanger 9 is also arranged between the concentrated sulfuric acid collection tank 7 and the spraying device 63. A plurality of condensing pipes with two openings are vertically distributed in the condensing cooler 6. The flue gas 10 treated by the condensation cooling absorber 6 is discharged through a chimney, and SO in the flue gas 2 The content is less than or equal to 15mg/m 3 . In addition, in order to prevent unexpected events such as power failure and the like and ensure the emission of flue gas, the flue gas emitted by the coke oven 1 and the dry quenching exhaust gas emitted by the dry quenching furnace 2 can be directly emitted to the chimney 10, and the process is controlled by valves between the coke oven 1 and the dry quenching furnace 2 and the chimney 10, and the valves are closed and opened in emergency during normal production.
A method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching scattered gas, by using the system, comprises the following steps:
s1, respectively mixing coke oven flue gas pumped from a coke oven 1 and coke dry quenching exhaust gas pumped from a coke dry quenching furnace 2, and entering a preprocessor 3 to remove dust and capture coke oil mist;
s2, introducing the mixed gas pretreated in the S1 into the reactor A4 for dedusting again, wherein the mixed gas is NO under the action of a catalyst x Conversion to N 2 ，SO 2 Conversion to SO 3 ；
S3, introducing the mixed gas converted by the S2 into the B reactor 5, wherein unconverted SO is contained in the mixed gas 2 Further conversion to SO 3 Then the flue gas containing sulfur trioxide introduced by the reactor B5 reacts with the desalted water to produce sulfurous acid, the sulfurous acid flows into a concentrated sulfuric acid collecting tank at the bottom from top to bottom along the inner wall of a glass condensing pipe inside the condensation cooling absorber 6, at the moment, the valve of the desalted water inlet 631 is closed, the valve of the sulfuric acid circulation spraying inlet 632 is opened, the sulfurous acid is pressurized by the pressurizing pump 8 and is sent to a spraying device 63 at the top of the condensation cooling absorber 6 through the sulfuric acid circulation spraying inlet 632 for circulation spraying, the sprayed sulfurous acid generates concentrated sulfuric acid with the concentration of 93% or 98% under the action of sulfur trioxide and oxygen in the continuously introduced flue gas, and the generated concentrated sulfuric acid is sent to a concentrated sulfuric acid storage tank of a tank area for sale or to a station area ammonium sulfate section using unit through the pressurizing pump 8.
The following is a specific description: a top-loading coke oven with a height of 7 m and a carbonization chamber with 3 multiplied by 65+55 holes and a dry quenching project matched with the top-loading coke oven are simultaneously constructed with a flue gas desulfurization, denitration and dust removal purification device. The two groups are divided into a 1# group which is 2 multiplied by 65 holes and is matched with 1 chimney, a 2# group which is 65+55 holes and is matched with 1 chimney. The total capacity of the coke oven and the dry quenching furnace is 280 ten thousand tons of coke/year, the total discharge of coke oven smoke and dry quenching gas is 900000Nm per hour 3 /h，SO 2 The content is 400mg/Nm 3 ，NO x The content is 900mg/Nm 3 Dust content of 46mg/Nm 3 。
As shown in FIG. 3, the coke oven flue gas and the dry quenching scattered gas discharged by the coke oven 1 and the dry quenching furnace 2 are mixed, the temperature of the mixed gas is 180-260 ℃, the mixed gas is connected in parallel to enter 2 preprocessors 3 (ceramic fiber filter pipes) for dedusting and capturing coke oil mist, the catalyst poisoning is prevented, and the single treatment capacity of the ceramic fiber filter is 450000Nm 3 And/h, the working temperature is 180-350 ℃, the working pressure resistance is at most above-5000 pa, the high temperature resistance and corrosion resistance are realized, the service life is above 10 years, and the dust is efficiently removed, so that the dust content is less than 5mg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the The pretreated mixed gas (temperature 200 ℃) was pressurized by an induced draft fan 31 (induced draft fan air volume 950000 Nm) 3 The suction force of the machine is 4-5KPa, the highest pressure of the machine is 10KPa, the fan impeller is an aluminum explosion-proof impeller, the fan matched motor is of EX explosion-proof grade, energy consumption equipment above grade II is safe and energy-saving), the explosion-proof grade is sent into a reactor A4 (a denitration and desulfurization integrated tower), and the top layer of the reactor A4 is provided with an activated carbon tar adsorption device with the thickness of 500mm for dedusting again; the second layer and the third layer are respectively SCR denitration catalyst beds with the thickness of 1200 mm; the fourth layer, the fifth layer and the sixth layer are three sections of sulfur dioxide conversion catalyst beds with the thickness of 1500mm respectively, and the mixed gas is formed in the V direction 2 O 5 NO under the action of AC catalyst x Conversion to N 2 ，SO 2 Conversion to SO 3 The method comprises the steps of carrying out a first treatment on the surface of the Introducing the mixed gas converted by the reactor A3 into a reactor B4 which is a sulfur dioxide converter, wherein a catalyst layer with the thickness of 1500mm is arranged in the mixed gas, and unconverted SO is contained in the mixed gas 2 Further conversion to SO 3 Then enters a condensation cooling absorber 6 for treatment, a spraying device 63 is arranged at the inner top of the condensation cooling absorber 6, a desalted water inlet 631 and a sulfuric acid circulation spraying inlet 632 are arranged on the spraying device 63, when the device is just opened, a valve of the desalted water inlet 631 is opened, desalted water is introduced into the spraying device 63 through the desalted water inlet 631 for spraying, the flue gas containing sulfur trioxide introduced by the B reactor 6 reacts with the desalted water to produce sulfurous acid, a cold air inlet 61 and a hot air outlet 62 are arranged on the condensation cooling absorber 6, the cold air inlet 61 is positioned below the hot air outlet 62, and the cold air isAfter being filtered by the air filter 611, the filtered cold air is conveyed into the reactor B by the cooling fan 612, the cold air condenses the interior from top to bottom, the generated sulfurous acid flows into the concentrated sulfuric acid collecting tank 7 at the bottom from top to bottom along the inner wall of the glass condensing pipe (vertically arranged and with two ends open) in the condensing and cooling absorber 6, at the moment, the valve of the desalted water inlet 631 is closed, the valve of the sulfuric acid circulating spraying inlet 632 is opened, the sulfurous acid in the concentrated sulfuric acid collecting tank 7 is pressurized by the pressurizing pump 8 and conveyed into the spraying device 63 at the top of the condensing and cooling absorber 6 through the sulfuric acid circulating spraying inlet 632 for circulating spraying, the sprayed sulfurous acid generates concentrated sulfuric acid with the concentration of 93% or 98% under the action of sulfur trioxide and oxygen in the continuously-introduced flue gas, the concentrated sulfuric acid concentration on-line detector is arranged below the concentrated sulfuric acid collecting tank 7 at the bottom of the condensing and cooling absorber 6 and used for detecting the concentration of the concentrated sulfuric acid, and the concentrated sulfuric acid is sampled and analyzed by the laboratory, at the moment, the concentrated sulfuric acid is 98% or 93% of the concentrated sulfuric acid can be conveyed to the concentrated sulfuric acid outside the tank area or the ammonium sulfate using unit through the pressurizing pump 8 for the valuable sulfuric acid tank area, and the valuable sulfuric acid can be purchased to the sale. The flue gas treated by the condensation cooling absorber 6 is discharged through a chimney 10, and SO in the flue gas 2 The content is less than or equal to 15mg/m 3 . In addition, in order to prevent unexpected events such as power failure and the like and ensure the emission of flue gas, the flue gas emitted by the coke oven 1 and the dry quenching exhaust gas emitted by the dry quenching furnace 2 can be directly emitted to the chimney 10, and the process is controlled by valves between the coke oven 1 and the dry quenching furnace 2 and the chimney 10, and the valves are closed and opened in emergency during normal production.
A heat exchanger 9 is further arranged between the concentrated sulfuric acid collecting tank 7 and the spraying device 63, so that the liquid in the concentrated sulfuric acid collecting tank is further cooled, and then is conveyed to the spraying device to be sprayed continuously.
In order to improve the condensation effect, a demineralized water cooler 52 is further disposed in the B reactor 5, and the flue gas treated by the sulfur dioxide conversion catalyst 51 is cooled by the demineralized water cooler 52 and then enters the condensation cooling absorber 6.
The invention uses coke oven flue gas containing sulfur dioxide to dry quench Jiao FangsanThe gas is used as raw material, the gas is firstly mixed, then impurity removal (dust removal and tar mist removal) is carried out, and then the mixed gas is converted (NO) x Conversion to N 2 ，SO 2 Conversion to SO 3 ) Under the action of water, the converted gas is used for preparing sulfuric acid, the prepared sulfuric acid is used by a coking plant, the outsourcing amount of the sulfuric acid is reduced, the production cost of the coking plant is reduced, and on the other hand, the SO of the exhaust gas is reduced 2 The content of the waste gas reaches the standard, so that the waste gas does not pollute the environment; the novel process for treating the coke oven flue gas and the dry quenching gas emissions solves the defects caused by the existing dry desulfurization and wet desulfurization, and the method is used for treating SO in the coke oven flue gas and the dry quenching gas emissions 2 The method changes waste into valuables, produces concentrated sulfuric acid for self-use or sale, is green and environment-friendly, can create benefits, belongs to the technical field of clean and environment-friendly production and circular economy, opens up a production process device which is more energy-saving, environment-friendly, cheaper, simpler and safer, and has good optimization effect on various indexes of a coke oven and a dry quenching oven; the invention has simple process flow, low investment cost, small occupied area, no need of continuously purchasing raw materials in the production process, low operation cost, no other wastes and no desulfurization ash, is more energy-saving and environment-friendly, has one-time investment, benefits for life, and has simple operation, high safety coefficient and high SO consumption 2 The produced concentrated sulfuric acid has better quality than the concentrated sulfuric acid produced by pyrite, larger market demand and large profit margin.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that such modifications and variations be included herein within the scope of the appended claims and their equivalents.
Claims (7)
1. A system for preparing concentrated sulfuric acid from coke oven flue gas and dry quenching blow-off gas, comprising:
the air inlet end of the preprocessor (3) is communicated with the air outlet ends of the coke oven (1) and the dry quenching furnace (2);
the reactor A (4) sequentially comprises an adsorption layer (41) positioned at the top, an SCR denitration catalyst bed (42) at the middle and a sulfur dioxide conversion catalyst bed (43) at the bottom along the flow direction of the flue gas, and the flue gas treated by the pre-processor (3) is pressurized and fed into the adsorption layer (41) through a draught fan (31); the adsorption layer (41) is an active carbon adsorption layer and is used for dedusting again;
a B reactor (5) containing a sulfur dioxide conversion catalyst (51);
a condensation cooling absorber (6) which is communicated with the outlet end of the B reactor (5), wherein a cold air inlet (61) and a hot air outlet (62) are arranged on the condensation cooling absorber (6), and the cold air inlet (61) is positioned below the hot air outlet (62); a spraying device (63) is arranged at the inner top of the condensation cooling absorber (6), and a desalted water inlet (631) and a sulfuric acid circulation spraying inlet (632) are arranged on the spraying device (63); the bottom of the condensation cooling absorber (6) is communicated with a concentrated sulfuric acid collecting tank (7), a pressurizing pump (8) is arranged between the concentrated sulfuric acid collecting tank (7) and the spraying device (63), one part of liquid in the concentrated sulfuric acid collecting tank (7) is conveyed to the spraying device (63) for circulating spraying through a sulfuric acid circulating spraying inlet (632) by the pressurizing pump (8), and the other part of liquid is delivered to a concentrated sulfuric acid storage tank of a tank area for sale or to an ammonium sulfate working section using unit of a factory; a plurality of glass condensing pipes with two open ends are vertically distributed in the condensing cooling absorber (6);
the method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching scattered gas comprises the following steps:
s1, respectively mixing coke oven flue gas pumped from a coke oven (1) and dry quenching exhaust gas pumped from a dry quenching furnace (2), and entering a preprocessor (3) to remove dust and capture coke oil mist;
s2, pressurizing the mixed gas pretreated by the S1 by an induced draft fan (31), introducing the mixed gas into the reactor A (4) for dedusting again, and carrying out NO on the mixed gas under the action of a catalyst x Conversion to N 2 ，SO 2 Conversion to SO 3 ；
S3, introducing the mixed gas converted by the S2 into a B reactor (5), wherein the mixed gas is not convertedConverted SO 2 Further conversion to SO 3 Introducing the flue gas containing sulfur trioxide introduced by the reactor B (5) and the desalted water react to produce sulfurous acid, the sulfurous acid flows into a concentrated sulfuric acid collecting tank (7) at the bottom from top to bottom along the inner wall of a glass condensing pipe inside the condensing and cooling absorber (6), and then is pressurized by a pressurizing pump (8) and conveyed into a spraying device (63) at the top of the condensing and cooling absorber (6) for circular spraying, and the sprayed sulfurous acid generates concentrated sulfuric acid with the concentration of 93% or 98% under the action of sulfur trioxide and oxygen in the continuously introduced flue gas;
after the flue gas exhausted from the gas outlet ends of the coke oven (1) and the dry quenching furnace (2) are mixed, the temperature of the flue gas entering the preprocessor (3) is 180-260 ℃, the catalyst adopted in the reactor A is a low-temperature catalyst or a medium-temperature catalyst, the working temperature of the low-temperature catalyst is 180-220 ℃, the working temperature of the medium-temperature catalyst is 250-300 ℃, and the flue gas is heated by a heating furnace when the flue gas temperature of the medium-temperature catalyst is lower than 250 ℃.
2. The system for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas according to claim 1, wherein the preprocessor (3) is a ceramic fiber filter, the number is 2, and the single processing amount is 450000Nm 3 And/h, wherein the working temperature is 180-350 ℃.
3. The system for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas according to claim 1, wherein the air volume of the induced draft fan (31) is 950000Nm 3 And/h, the suction force of the front part of the machine is 4-5KPa, the highest pressure of the rear part of the machine is 10KPa, the fan impeller is an aluminum explosion-proof impeller, and the fan matched motor is E X Explosion-proof level.
4. The system for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas according to claim 1, wherein a demineralized water cooler (52) is further arranged in the reactor B (5), and flue gas treated by the sulfur dioxide conversion catalyst (51) enters the condensation cooling absorber (6) after being cooled by the demineralized water cooler (52).
5. The system for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas according to claim 1, characterized in that a heat exchanger (9) is also arranged between the concentrated sulfuric acid collecting tank (7) and the spraying device (63).
6. The system for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas according to claim 1, characterized in that flue gas treated by the condensation cooling absorber (6) is discharged through a chimney (10), and SO is contained in the flue gas 2 The content is less than or equal to 15mg/m 3 。
7. A method for preparing concentrated sulfuric acid by using coke oven flue gas and dry quenching exhaust gas, which is characterized by using the system as claimed in any one of claims 1-6, comprising the following steps:
s1, respectively mixing coke oven flue gas pumped from a coke oven (1) and dry quenching exhaust gas pumped from a dry quenching furnace (2), and entering a preprocessor (3) to remove dust and capture coke oil mist;
s2, pressurizing the mixed gas pretreated by the S1 by an induced draft fan (31), introducing the mixed gas into the reactor A (4) for dedusting again, and carrying out NO on the mixed gas under the action of a catalyst x Conversion to N 2 ，SO 2 Conversion to SO 3 ；
S3, introducing the mixed gas converted by the S2 into a B reactor (5), wherein unconverted SO is in the mixed gas 2 Further conversion to SO 3 Then the flue gas is introduced into a condensation cooling absorber (6) for condensation treatment, desalted water is introduced into the condensation cooling absorber (6) through a desalted water inlet (631) when the operation is just started, the desalted water is sprayed on the top of the condensation cooling absorber (6) through a spraying device (63), the flue gas containing sulfur trioxide introduced into a reactor B (5) reacts with the desalted water to produce sulfurous acid,the sulfurous acid flows into a concentrated sulfuric acid collecting tank (7) at the bottom from top to bottom along the inner wall of a glass condensing pipe inside the condensing and cooling absorber (6), then is pressurized and sent to a spraying device (63) at the top of the condensing and cooling absorber (6) by a pressurizing pump (8) to be circularly sprayed, and the sprayed sulfurous acid generates concentrated sulfuric acid with the concentration of 93 percent or 98 percent under the action of sulfur trioxide and oxygen in the continuously-introduced flue gas.
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