CN212575985U - Ultralow emission treatment system for coke oven flue gas - Google Patents

Ultralow emission treatment system for coke oven flue gas Download PDF

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CN212575985U
CN212575985U CN202020335539.3U CN202020335539U CN212575985U CN 212575985 U CN212575985 U CN 212575985U CN 202020335539 U CN202020335539 U CN 202020335539U CN 212575985 U CN212575985 U CN 212575985U
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heat exchanger
coke oven
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娄爱娟
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Censtron Environmental Technology & Engineering Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/343—Heat recovery
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

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Abstract

The utility model provides a novel coke oven flue gas desulfurization, denitration and dust removalThe comprehensive treatment system for waste heat utilization and white smoke elimination is characterized in that: the desulfurization by-product can be utilized, no secondary waste is generated, the operation stability is high, the service life of the catalyst is long, the problems of white smoke tailing and the like are avoided, and the operation cost is low. The utility model discloses a coke oven flue gas ultralow emission treatment system includes wet flue gas desulfurization device and denitrification facility. Wherein, the wet desulphurization device is used for removing SO in the coke oven flue gas2Smoke dust and denitration device for removing NO in coke oven flue gasxAnd the denitration device is positioned at the downstream of the wet desulphurization device. The utility model adopts the scheme of firstly desulfurizing (and dedusting) and then denitrating, thereby eliminating SO2And the negative effects of smoke dust and tar on the denitration catalyst and subsequent waste heat boiler equipment.

Description

Ultralow emission treatment system for coke oven flue gas
Technical Field
The utility model belongs to the coking field, in particular to a coke oven flue gas ultralow emission treatment system.
Background
All gases have similar properties and contain SO2、NOx(nitrogen oxides) and dust, etc., are required to be desulfurized, denitrated and dedusted. However, the sources vary, as do the amounts and composition of other contaminants, particularly the temperature. The desulfurization, denitration and dust removal of boiler flue gas are mature, and can reach the ultra-low emission standard (SO under 6 percent of oxygen content)2≤35mg/Nm3，NOx≤50mg/Nm3Dust less than or equal to 10mg/Nm3). In addition, in some urban areas or densely populated areas, the emission of boiler flue gas also has temperature requirements, and the temperature of the flue gas is required to be higher than 70-80 ℃ so as to reduce the influence of white smoke pollution.
However, in the coking field, the treatment of the flue gas is just started, because the coke oven flue gas is greatly different from the boiler flue gas, and the technical route of the boiler flue gas is difficult to adopt. The coke oven flue gas has the following characteristics:
(1) the coke oven flue gas parameters of coke-oven plants are different, and the factors influencing the components of the coke oven flue gas comprise the production process of the coke oven, the oven type, the type of heating fuel, the operation system of the coke oven, the organic sulfur content of coking raw material coal, the blowby of the coke oven and the like.
(2) The power plant can find a flue gas temperature interval of 320-380 ℃, a conventional SCR catalytic denitration technology can be adopted, while the coke oven cannot find the similar temperature interval and cannot adopt the conventional SCR catalytic denitration technology. The temperature of the coke oven flue gas is relatively low, is 180-300 ℃, and is mostly 200-260 ℃; when the blast furnace gas is used for heating the coke oven, the temperature of the flue gas is lower (lower than 200 ℃).
(3) SO in coke oven flue gas2The content is not high, but the range is wide, and is from 60 to 600mg/m3；NOxThe content difference is large and is from 400 to 1200mg/m3(ii) a The water content is higher, 17-20%.
(4) The components of the coke oven flue gas are periodically fluctuated along with the operation of the coke oven hydraulic exchanger, and SO in the flue gas2、NOxAnd the difference between the peak and the trough of the oxygen content is large.
(5) The components of the coke oven flue gas are complex and changeable, and the coke oven flue gas contains hydrogen sulfide, carbon monoxide, methane, tar and the like.
Aiming at the problems of air pollution in China, the recent national institute of development and improvement, department of energy and environmental protection will have new emission standards, and SO thereof2≤50mg/Nm3，NO2≤150mg/Nm3. In the power industry, boiler and power plant flue gases have implemented new more stringent standards, i.e. ultra low emission standards: SO (SO)2≤35mg/Nm3Dust less than or equal to 10mg/Nm3，NOx≤50mg/Nm3. In the foreseeable future, coke oven flue gas will also implement ultra-low emission standards for the boiler industry.
For NOxBy improving the heating system of the coke oven, controlling the temperature of the coke oven, combining the waste gas circulation with the sectional heating technology of the coke oven, improving the structure of the oven body of the coke oven and the like, NO can be controlledxContent in coke oven flue gas, NOxDown to 400mg/Nm3Left and right. For SO2The sulfur content of the return coke gas can be reduced to 50mg/Nm by controlling the sulfur content of the coking coal, deeply desulfurizing the coking coal gas by adopting a desulfurization process, or using the blast furnace gas as fuel3The following. Of course, the above measures are not all commonly used,and in most cases, SO of flue gas2And NOxThe content of (A) is still higher than the ultralow emission standard, and a desulfurization device, particularly a denitration device needs to be constructed in a matching way.
The existing flue gas desulfurization technologies are roughly classified into a calcium method, a sodium method and an ammonia method. The calcium method and the sodium method are dry methods and wet methods, and the ammonia method is a wet method. Both the calcium method and the sodium method can generate solid waste and secondary pollution, and are difficult to treat. As for coke-oven plants, it is well known that ammonia exists in coal gas and can be recovered to obtain ammonia water, therefore, dry desulfurization of coke oven flue gas is the most ideal method, and the obtained ammonium sulfate can be sold as a chemical fertilizer and is a clean production route. However, due to SO of the coke oven flue gas2The content is not high, and the ammonia desulphurization technology widely used in the boiler flue gas treatment can not be directly used for the coke oven flue gas.
The existing denitration method, especially the industrialized method, adopts a vanadium catalyst loaded on a titanium dioxide carrier. The traditional catalyst adopts tungsten trioxide as an auxiliary agent, the using temperature range is 320-400 ℃, the catalyst is deactivated by sintering due to overhigh temperature, and SO in flue gas is caused due to overlow temperature3Production of NH in combination with ammonia4HSO4Adsorption blocks the micropores of the catalyst, resulting in deactivation of the catalyst, and more seriously, direct blocking of the equipment. The temperature of the coke oven flue gas is lower than the temperature requirement of the existing vanadium catalyst. In order to use the existing denitration techniques, various methods have been proposed in the literature, for example, chinese patent applications CN104324612A, CN104258673A, CN106139897A, CN106334444A, CN106237845A, CN105688936A, CN108339384A, CN108686505A, and the like. CN108686505A discloses a coke oven gas denitration method with gas auxiliary hot blast stove reheating function, which consumes additional gas to periodically regenerate a denitration reactor.
As for the coupled mode of flue gas desulfurization and denitration, the above patent applications disclose a mode of denitration before desulfurization, which has two problems: the first problem is that smoke dust and tar in the coke oven smoke can adhere to the catalyst to block honeycomb holes, so that the resistance of the reactor is increased; the second problem is that there is waste heat utilization's boiler between denitrification facility and desulphurization unit, appears boiler heat exchange tube adhesion ammonium bisulfate easily, leads to heat exchange efficiency to reduce the problem of blockking up the boiler at last, leads to stopping at last to adopt high pressure water washing, has influenced the stability and the security of production. In addition, if wet desulphurization is adopted, the problem of white smoke pollution caused by tail of discharged smoke usually occurs because the temperature of discharged smoke is low and the humidity of the discharged smoke is high.
Therefore, a coupling mode of desulfurization before denitration is also proposed, but because the flue gas temperature is high, the traditional calcium desulfurization technology cannot be used, so that sodium carbonate or sodium bicarbonate can only be used as a desulfurization reagent to obtain a desulfurization byproduct of sodium sulfate, such as chinese patent applications CN105214478A, CN106731585A, CN206730850U, CN106925108A, CN207838677U, CN208066118U, CN108201781A, and the like. The disadvantages of this type of technique are the high price of the desulfurizing agent and the low use of the by-products.
Therefore, the prior art has the problems of high cost, difficult reuse of byproducts, poor operation stability, short service life of the catalyst, white smoke tailing and the like, so that the development of a novel comprehensive treatment and waste heat utilization technology for the coke oven smoke has important significance.
SUMMERY OF THE UTILITY MODEL
In view of the above-mentioned defects of the prior art, an object of the utility model is to provide a new comprehensive treatment system of coke oven flue gas desulfurization, denitration, dust removal, waste heat utilization and white smoke elimination, this system characteristic is: the desulfurization by-product can be utilized, no secondary waste is generated, the operation stability is high, the service life of the catalyst is long, the problems of white smoke tailing and the like are avoided, and the operation cost is low.
In order to achieve the above object, in one aspect, the utility model provides a coke oven flue gas ultra-low emission treatment system, which comprises a wet desulphurization device and a denitration device. Wherein, the wet desulphurization device is used for removing SO in the coke oven flue gas2Smoke dust and denitration device for removing NO in coke oven flue gasxAnd the denitration device is positioned at the downstream of the wet desulphurization device. The utility model adopts the scheme of firstly desulfurizing (and dedusting) and then denitrating, thereby eliminating SO2And the negative effects of smoke dust and tar on the denitration catalyst and subsequent waste heat boiler equipment.
Further, the utility model discloses a coke oven flue gas ultralow emission treatment system still includes exhaust-heat boiler, is located denitrification facility's low reaches, and its entry is connected with denitrification facility's export for flue gas after the denitration carries out waste heat recovery, turns into the steam energy with the sensible heat in the flue gas.
Further, the coke oven flue gas ultra-low emission treatment system of the utility model also comprises a first heat exchanger and a second heat exchanger, which respectively comprise a cooling section and a reheating section. The cooling section of the first heat exchanger is positioned on an inlet flue of the desulfurization device and used for cooling and heating the raw flue gas; the reheating section of the first heat exchanger is positioned on a flue between an inlet of the denitration device and an outlet of the reheating section of the second heat exchanger and used for heating the desulfurized flue gas. The reheating section of the second heat exchanger is used for preheating the desulfurized flue gas, the inlet of the reheating section of the second heat exchanger is connected with the outlet of the wet desulphurization device, and the outlet of the reheating section of the second heat exchanger is connected with the inlet of the reheating section of the first heat exchanger; the cooling section of the second heat exchanger is used for cooling and heating the denitrated flue gas, an inlet of the second heat exchanger is connected with an outlet of the waste heat boiler, and an outlet of the second heat exchanger is connected with downstream equipment.
Further, the first heat exchanger is preferably an oil medium heat exchanger and comprises a cooling section and a reheating section, the heat transfer medium is heat transfer oil, the heat transfer oil is conveyed by an oil pump to flow between the cooling section and the reheating section, the boiling point of the heat transfer oil is more than 300 ℃, and the heat transfer oil is suitable for high-temperature heat transfer. The second heat exchanger is preferably a water medium heat exchanger and comprises a cooling section and a reheating section, the heat transfer medium is desalted water, and the desalted water is conveyed by a water pump to flow between the cooling section and the reheating section. The oil-medium heat exchanger and the water-medium heat exchanger adopt fin heat exchange tubes, the spacing between fins is 2-10mm, and the height of the fins is 10-50mm, so that the efficiency of the heat exchanger can be improved, and the equipment investment can be saved.
Further, a cooling section of the oil-coal heat exchanger, a wet desulphurization device, a reheating section of the water-borne heat exchanger, a reheating section of the oil-borne heat exchanger, a denitration device, a waste heat boiler and a cooling section of the water-borne heat exchanger are sequentially connected between the original flue gas of the coke oven and the ultra-clean flue gas through a flue, so that the temperature of the flue gas entering a denitration reactor of the denitration device is more than 180 ℃, and is preferably 180-280 ℃; and the discharge temperature of the ultra-clean flue gas is more than 100 ℃, and is preferably between 100 ℃ and 130 ℃.
Further, the wet desulfurization unit is preferably an ammonia desulfurization tower comprising at least two water absorption cycle sections, typically, for example, two, three, four, or five water absorption cycle sections. The desulfurization raw materials is ammonia, aqueous ammonia or liquid ammonia, and the desulfurization product is ammonium sulfate aqueous solution or solid, ensures to adopt the product of coke-oven plant's self-production as the desulfurization raw materials, realizes making useless with the waste, and the desulfurization product is the ammonium sulfate simultaneously, can do the chemical fertilizer, and the usage is great, has eliminated the pollution of secondary waste, can realize very high desulfurization and dust collection efficiency moreover, provides better operational reliability for subsequent denitration.
Furthermore, the denitration device is an SCR reaction device, the catalyst is a vanadium-titanium catalyst containing molybdenum oxide, the denitration raw material is ammonia gas, ammonia water or liquid ammonia, the gas-phase catalytic reduction technology using ammonia as the raw material is ensured, the equipment is simple and reliable, and particularly, the low-temperature denitration at the temperature of above 160 ℃ can be realized by using the molybdenum-containing catalyst with better low-temperature activity. The catalyst is a honeycomb catalyst, the honeycomb holes are square holes or round holes, and the aperture is 3-5mm, so that the efficiency of the catalyst can be improved, the filling height of the catalyst can be reduced, the equipment investment can be saved, the smoke resistance can be reduced, and the energy consumption can be saved.
On the other hand, the utility model also provides a method for adopting above-mentioned coke oven flue gas ultralow emission treatment system to handle coke oven flue gas, including the following step:
(1) heat transfer oil of the flue gas is used for heat extraction: introducing the raw flue gas with higher temperature into a cooling section of the oil medium heat exchanger, carrying out countercurrent heat exchange with heat conduction oil conveyed by an oil pump, extracting sensible heat in the raw flue gas, storing the sensible heat in the heat conduction oil, heating the heat conduction oil, and cooling the raw flue gas;
preferably, the temperature of the raw flue gas is between 200 and 290 ℃, and the temperature is reduced to between 100 and 140 ℃ after the step (1);
(2) flue gas desulfurization by ammonia method: introducing the cooled flue gas into a wet desulphurization device, wherein the wet desulphurization device is at least provided with two water absorption circulation sections, and SO in the flue gas2Absorbed, reacted with desulfurizer ammonia and re-oxidized into ammonium sulfate; smoke and dust in flue gasSimultaneously washing and removing carbon smoke, tar and the like;
preferably, the relative densities of the washing liquids of the two water absorption cycle sections are between 1.1 and 1.3 and less than 1.01, respectively; SO of desulfurized flue gas2The content is less than 35mg/Nm3More preferably less than 10mg/Nm3(ii) a The smoke content is less than 10mg/Nm3More preferably less than 5mg/Nm3(ii) a The temperature is 55-65 ℃;
(3) preheating hot water of flue gas: introducing the desulfurized flue gas into a reheating section of the hydrophily heat exchanger, and preheating the desulfurized flue gas by hot water in the hydrophily heat exchanger;
preferably, the temperature of the flue gas is raised from 55-65 ℃ to 100-120 ℃;
(4) heating the flue gas by heat conduction oil: introducing the flue gas preheated by hot water into a reheating section of the oil medium heat exchanger, and performing countercurrent heat exchange with heat-conducting oil which is from a cooling section of the oil medium heat exchanger and absorbs the heat of the original flue gas, so that the temperature is increased;
preferably, the temperature of the flue gas is raised to 160-260 ℃;
(5) flue gas SCR denitration: introducing the heated flue gas into a denitration device, and carrying out SCR reaction with denitration reagent ammonia under the catalytic action of a vanadium-titanium catalyst containing molybdenum oxide to obtain NO in the flue gasxIs converted into nitrogen and water;
preferably, NO in denitrated flue gasxThe content is less than 50mg/Nm3More preferably less than 30mg/Nm3；
(6) Flue gas waste heat utilization: introducing the denitrated flue gas into a waste heat boiler, converting sensible heat in the flue gas into steam energy, and reducing the temperature of the flue gas;
preferably, the pressure of the steam is 0.3-0.6MPa, and the temperature of the flue gas is reduced to 140-170 ℃;
(7) hot water heating of flue gas: introducing the flue gas from the step (6) into a cooling section of the water medium heat exchanger, performing countercurrent heat exchange with hot water pumped from a reheating section of the water medium heat exchanger by a water pump, taking out sensible heat of the flue gas, storing the sensible heat in the hot water, and further reducing the temperature of the flue gas;
preferably, the temperature of the flue gas is reduced to 90-130 ℃;
(8) smoke extraction and emission: and (4) pumping the flue gas from the step (7) to a chimney through an induced draft fan and discharging the flue gas into the atmosphere.
Preferably, the discharge temperature of the flue gas is between 100 ℃ and 130 ℃, and NO isxThe content is less than 50mg/Nm3，SO2The content is less than 10mg/Nm3The smoke content is less than 10mg/Nm3Therefore, the ultra-clean emission of the coke oven smoke without the influence of white smoke can be realized under a wide range of smoke conditions.
The utility model discloses a coke oven flue gas ultralow emission treatment system's beneficial technological effect shows in following aspect at least:
(1) the influence of ammonium bisulfate, smoke dust and tar on the denitration reactor and the catalyst is eliminated, and the service life of the reactor and the catalyst is prolonged;
(2) the influence of ammonium bisulfate on the waste heat boiler is eliminated, and the operation stability and efficiency of the boiler are improved;
(3) the waste ammonia water produced by the coking plant is adopted, the waste is treated by the waste, the raw material cost is low, and the problem of secondary waste is also solved;
(4) the emission temperature of the smoke is more than 100 ℃, so that white smoke pollution can be eliminated;
(5) can realize the ultra-low emission index and has good environmental protection benefit.
In a word, adopt the utility model discloses a coke oven flue gas desulfurization denitration dust removal and waste heat utilization disappear white coupled system and method, comprehensive properties is superior to prior art, and environmental protection, society and economic benefits are showing.
Drawings
FIG. 1 is a schematic flow chart of a coke oven flue gas ultra-low emission treatment system according to a preferred embodiment of the present invention.
Detailed Description
The following embodiments of the present invention will be described in detail, and the following embodiments are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.
Example 1
A coke oven of 130 ten thousand tons/year is arranged in a certain coke plant, and the smoke gas amount is 27 ten thousand Nm3Hr, raw flue gas temperature 260 deg.C, in which SO2＝100mg/Nm3，NOx＝1000mg/Nm3Smoke dust 50mg/Nm3The coke oven flue gas ultra-low emission treatment system of the embodiment is applied to treat coke oven flue gas.
As shown in fig. 1, the coke oven flue gas ultra-low emission treatment system of the embodiment includes a wet desulfurization device 100, a denitration device 200, a waste heat boiler 300, an induced draft fan 400, a chimney 500, an oil medium heat exchanger 600, and a water medium heat exchanger 700. The cooling section 601 of the oil-coal heat exchanger 600, the wet desulphurization device 100, the reheating section 702 of the water medium heat exchanger 700, the reheating section 602 of the oil medium heat exchanger 600, the denitration device 200, the exhaust-heat boiler 300, the cooling section 701 of the water medium heat exchanger 700, the induced draft fan 400 and finally the chimney 500 are sequentially connected between the coke oven raw flue gas and the ultra-clean flue gas through a flue, so that a complete comprehensive treatment system is formed.
The oil medium heat exchanger 600 comprises a cooling section 601 and a reheating section 602, the heat transfer medium is heat transfer oil, the specification of the heat transfer oil is L-QC320, the heat transfer oil is conveyed to flow between the cooling section 601 and the reheating section 602 through an oil pump 603, and heat is transferred to the low-temperature desulfurized and purified flue gas from high-temperature raw flue gas. The water medium heat exchanger 700 comprises a cooling section 701 and a reheating section 702, the heat transfer medium is desalted water, the desalted water is conveyed by a water pump 703 to flow between the cooling section 701 and the reheating section 702, and the heat of the hot clean flue gas at the outlet of the waste heat boiler 300 is transferred to the desulfurized and purified flue gas. The oil heat exchanger 600 and the water heat exchanger 700 adopt fin heat exchange tubes, the spacing between fins is 3mm, the height of the fins is 25mm, and the outer diameter of the heat exchange tubes is 25 mm.
The wet desulfurization device 100 employs an ammonia desulfurization device, and includes two water absorption circulation sections, the desulfurization raw material is ammonia gas, and the desulfurization product is an ammonium sulfate aqueous solution with a concentration of 30% wt. The denitration device 200 is an SCR reaction device, the catalyst is a vanadium-titanium catalyst containing molybdenum oxide, and the denitration raw material is ammonia gas; the catalyst is a honeycomb catalyst, honeycomb holes are square holes, and the equivalent aperture is 4 mm.
The coke oven flue gas ultra-low emission treatment system of the embodiment is adopted to carry out ultra-low emission treatment on coke oven flue gas, and the method comprises the following steps:
(1) flue gas heat conduction oil heat extraction: introducing the raw flue gas with higher temperature into a cooling section 601 of the oil medium heat exchanger 600, performing countercurrent heat exchange with heat conduction oil conveyed by an oil pump 603, extracting sensible heat in the raw flue gas, storing the sensible heat in the heat conduction oil, heating the heat conduction oil, and cooling the raw flue gas to 140 ℃;
(2) flue gas desulfurization by ammonia method: introducing the cooled flue gas into a wet desulphurization device 100, wherein the desulphurization device is provided with two washing sections, the densities of the washing liquids are 1.15 and 1.005 respectively, and SO in the flue gas is2Absorbed, reacted with desulfurizing agent ammonia and re-oxidized into ammonium sulfate, the smoke dust in the smoke including carbon smoke and tar is simultaneously washed and removed, and SO of the desulfurized smoke is2Content 8mg/Nm3Smoke content 4.5mg/Nm3At a temperature of 60 ℃;
(3) preheating hot water of flue gas: introducing the desulfurized flue gas into a reheating section 701 of a water medium heat exchanger 700, and heating the flue gas by hot water to raise the temperature from 60 ℃ to 110 ℃;
(4) heating the flue gas by heat conduction oil: introducing the preheated flue gas into a reheating section 602 of the oil medium heat exchanger 600, and performing countercurrent heat exchange with heat conduction oil which absorbs the heat of the original flue gas from a cooling section 601, wherein the temperature is raised to 230 ℃;
(5) flue gas SCR denitration: introducing the added flue gas into a denitration device 200, and carrying out SCR reaction with denitration reagent ammonia under the catalytic action of a vanadium-titanium catalyst containing molybdenum oxide to obtain NO in the flue gasxIs converted into nitrogen and water, NO in the flue gasxContent 28mg/Nm3；
(6) Flue gas waste heat utilization: introducing the denitrated flue gas into a waste heat boiler 300, and converting sensible heat in the flue gas into steam energy, wherein the pressure of the steam is 0.5MPa, and the temperature of the flue gas is reduced to 160 ℃;
(7) hot water heating of flue gas: introducing the flue gas obtained in the step (6) into a cooling section 701 of a heat medium heat exchanger 700, performing countercurrent heat exchange with hot water sent from a reheating section 702 by a water pump 703, taking out sensible heat of the flue gas, storing the sensible heat in the hot water, and reducing the temperature of the flue gas to 110 ℃;
(8) smoke extraction and emission: and (4) pumping the flue gas from the step (7) to a chimney 500 through an induced draft fan 400 and discharging the flue gas into the atmosphere.
The temperature of the raw flue gas of the coke oven is 230 ℃, the temperature of the ultra-clean flue gas is 110 ℃, and NO is addedxThe content is 45.5mg/Nm3，SO2Content 8mg/Nm3Smoke content 4.5mg/Nm3And the byproduct of steam of 0.5Mpa is 9.5 tons/hr, and no white smoke tailing occurs.
Example 2
One coke oven of 100 ten thousand tons/year is arranged in a certain coke plant, and the smoke gas amount is 21 ten thousand Nm3Hr, raw flue gas temperature 230 deg.C, wherein SO2＝80mg/Nm3，NOx＝800mg/Nm3Smoke dust 100mg/Nm3After the coke oven flue gas ultra-low emission purification and waste heat utilization coupling treatment system and method which are the same as those in the embodiment 1 are applied for treatment, the ultra-clean flue gas temperature is 110 ℃, and NO isxThe content is 25.5mg/Nm3，SO2The content is 3.2mg/Nm3Smoke dust 4.8mg/Nm3The byproduct of steam of 0.5Mpa is 7.5 tons/hr, and no white smoke tailing occurs.
Example 3
One coke oven of 170 ten thousand tons/year in a certain coke plant has the smoke amount of 35 ten thousand Nm3Hr, raw flue gas temperature 280 deg.C, in which SO2＝66mg/Nm3，NOx＝1000mg/Nm370mg/Nm smoke3The coke smoke ultra-low emission purification and waste heat utilization coupling treatment system which is approximately the same as that of the embodiment 1 is applied, the catalyst is a honeycomb catalyst, honeycomb holes are square holes, and the aperture is 5 mm; the oil medium heat exchanger 600 and the water medium heat exchanger 700 adopt fin heat exchange tubes, the spacing between fins is 2.6mm, the height of the fins is 35mm, and the outer diameter of the heat exchange tubes is 32 mm; the obtained ultra-clean flue gas has a temperature of 120 deg.C and NOxThe content is 25.5mg/Nm3，SO2The content is 3.2mg/Nm3Soot 4.1mg/Nm3And the byproduct steam of 0.5Mpa is 18 tons/hr, and the phenomenon of white smoke tailing does not occur.
The foregoing has described in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the teachings of this invention without undue experimentation. Therefore, the technical solutions that can be obtained by a person skilled in the art through logic analysis, reasoning or limited experiments based on the prior art according to the concepts of the present invention should be within the scope of protection defined by the claims.

Claims (8)

1. A coke oven flue gas ultra-low emission abatement system, characterized in that, the abatement system includes:
a wet desulphurization device for removing SO in the coke oven flue gas2And smoke;
denitration device for removing NO in coke oven flue gasxThe denitration device is positioned at the downstream of the wet desulphurization device; and the number of the first and second groups,
the system comprises a first heat exchanger and a second heat exchanger, wherein the first heat exchanger and the second heat exchanger respectively comprise a cooling section and a reheating section; wherein the content of the first and second substances,
the cooling section of the first heat exchanger is positioned on an inlet flue of the desulfurization device and is used for cooling and heating the raw flue gas;
the reheating section of the first heat exchanger is positioned on a flue between the inlet of the denitration device and the outlet of the reheating section of the second heat exchanger and is used for heating desulfurized flue gas;
the reheating section of the second heat exchanger is used for preheating desulfurized flue gas, the inlet of the reheating section of the second heat exchanger is connected with the outlet of the wet desulphurization device, and the outlet of the reheating section of the second heat exchanger is connected with the inlet of the reheating section of the first heat exchanger;
the cooling section of the second heat exchanger is used for cooling and heating the denitrated flue gas, and the cooling section of the second heat exchanger is positioned at the downstream of the denitration device.
2. The coke oven flue gas ultra-low emission treatment system of claim 1, wherein the treatment system further comprises a waste heat boiler located at the downstream of the denitration device, and an inlet of the waste heat boiler is connected with an outlet of the denitration device, and is used for recovering waste heat from the denitrated flue gas and converting sensible heat in the flue gas into steam energy.
3. The coke oven flue gas ultra-low emission abatement system of claim 2, wherein an inlet of the cooling section of the second heat exchanger is connected with an outlet of the waste heat boiler, and an outlet of the cooling section of the second heat exchanger is connected with downstream equipment.
4. The coke oven flue gas ultra-low emission abatement system of claim 3, wherein,
the first heat exchanger is an oil medium heat exchanger and comprises a cooling section and a reheating section, the heat transfer medium is heat transfer oil, and the heat transfer oil is conveyed by an oil pump to flow between the cooling section and the reheating section;
the second heat exchanger is a water medium heat exchanger and comprises a cooling section and a reheating section, the heat transfer medium is desalted water, and the desalted water is conveyed by a water pump to flow between the cooling section and the reheating section.
5. The coke oven flue gas ultra-low emission treatment system of claim 4, wherein the boiling point of the heat transfer oil is greater than 300 ℃; the oil medium heat exchanger and the water medium heat exchanger adopt fin heat exchange tubes, the spacing between fins is 2-10mm, and the height of the fins is 10-50 mm.
6. The coke oven flue gas ultra-low emission treatment system of any one of claims 1 to 5, wherein the wet desulphurization device is an ammonia desulphurization tower comprising at least two water absorption cycle sections, the desulphurization raw material is ammonia gas, ammonia water or liquid ammonia, and the desulphurization product is an ammonium sulfate aqueous solution or solid.
7. The coke oven flue gas ultra-low emission treatment system of claim 6, wherein the denitration device is an SCR reaction device, the catalyst is a vanadium-titanium catalyst containing molybdenum oxide, and the denitration raw material is ammonia gas, ammonia water or liquid ammonia.
8. The coke oven flue gas ultra-low emission treatment system of claim 7, wherein the catalyst is a honeycomb catalyst, the honeycomb holes are square holes or round holes, and the pore diameter is between 3mm and 5 mm.
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