CN211936384U - Flue gas denitration and dust removal device for alkali recovery furnace in papermaking industry - Google Patents

Flue gas denitration and dust removal device for alkali recovery furnace in papermaking industry Download PDF

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CN211936384U
CN211936384U CN202020228232.3U CN202020228232U CN211936384U CN 211936384 U CN211936384 U CN 211936384U CN 202020228232 U CN202020228232 U CN 202020228232U CN 211936384 U CN211936384 U CN 211936384U
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flue gas
denitration
recovery furnace
alkali recovery
dust collector
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吴金泉
曾连辉
吴思温
赖英坤
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Fujian Xinze Environmental Protection Equipment And Engineering Co ltd
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Fujian Xinze Environmental Protection Equipment And Engineering Co ltd
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Abstract

The utility model relates to a paper industry alkali recovery furnace flue gas denitration dust collector, the flue gas comes out from alkali recovery furnace, loop through dry electric dust remover, the draught fan, the flue gas heat exchanger, steam heater, the SCR reactor, flue gas washing tower, the defroster, wet electric dust remover, the back is discharged along with direct vent chimney, this device adopts the process thought of degree of depth dust removal again of denitration behind the high-efficient dust removal earlier, can guarantee the nitre, the dirt reaches ultralow emission in step, simultaneously because adopt middle and high temperature denitration, can improve denitration efficiency, the live time of extension catalyst, the stability of the operation of improvement device.

Description

Flue gas denitration and dust removal device for alkali recovery furnace in papermaking industry
Technical Field
The utility model relates to a paper industry alkali recovery furnace flue gas denitration dust collector.
Background
In the paper making industry, a large amount of waste liquor (commonly called as black liquor) is generated in the alkaline pulping process, wherein the waste liquor contains a large amount of organic matters and inorganic matters, and in order to reduce the pollution of the black liquor discharge to the environment and fully utilize the residual value of the black liquor, the paper making industry generally adopts an alkaline recovery furnace to treat and recycle the waste liquor.
The concentrated black liquor contains about 50-80% of solid matters, wherein about 70% of the solid matters are organic matters such as lignin, hemicellulose and cellulose degradation products and organic acids dissolved from plant fibers, and 30% of the solid matters are inorganic matters such as sodium hydroxide, sodium carbonate, sodium sulfide, sodium sulfate and silicon dioxide. The alkali recovery furnace has the functions of separating organic matter from inorganic salt in black liquor by means of pyrolysis, burning concentrated black liquor, burning organic matter at high temperature in the alkali recovery furnace to release heat and produce steam for concentrating, evaporating and other work sections, and generating electricity for power equipment. The inorganic salt is in a molten state under the high-temperature condition in the furnace, is discharged from the furnace bottom, enters a causticization working section, converts sodium carbonate in the inorganic salt into sodium hydroxide, and then returns to the cooking working section for recycling.
In the current mainstream alkali recovery furnace, the initial concentration of smoke dust in the smoke is generally 10-30 g/Nm3, the smoke dust components mainly comprise soluble Na2SO4 and soluble Na2CO3, the proportion of the smoke dust components is about 90%, dry electric dust removal is generally used as the dust removal first choice of the smoke gas of the alkali recovery furnace, and an electric dust remover with 4 electric fields or 3 electric fields is configured to control the smoke dust to be below 100mg/Nm3 (under special conditions, such as polar plate corrosion and dust adhesion of the electric dust remover, the operation of the electric dust remover deviates from a normal design value, and the dust at the outlet of the electric dust remover can reach 500-600 mg/Nm 3).
The initial concentrations of SO2 and NOx in the flue gas of the soda recovery furnace vary according to the adjustment of black liquor components, concentration, air distribution conditions, operation control of the soda recovery furnace, and the like. In general, in order to control a high sulfur reduction rate, the operating temperature of the soda recovery furnace is increased to effectively reduce the emission concentration of SO2, but the emission concentration of NOx is increased. Conversely, the emission concentration of SO2 increases and the emission concentration of NOx decreases. Therefore, for areas with low requirements on SO2 and NOx emission standards, enterprises can meet the requirements on corresponding emission indexes through means of corresponding operation mode adjustment, air distribution transformation and the like, but the existing denitration dust removal device has single function, low denitration efficiency and high energy consumption.
The flue gas emission of the alkali recovery furnace in the paper making industry has no corresponding industry standard so far, and the 2014 national environmental protection department mentions the following by a ring letter [ 2014 ] 124 text of a compound letter of opinions about the emission standard of flue gas execution of the alkali recovery furnace and a request for the problem of emission standard of flue gas execution of the alkali recovery furnace of Jiangsu Wangzi paper making Limited company in the environmental protection hall of Jiangsu province: the black liquor produced in the pulping process of paper making contains organic matters (the main components are lignin, hemicellulose and the like) and inorganic matters, and is combusted through an alkali recovery furnace after being evaporated and concentrated to produce steam or generate electricity. In consideration of the difference between the alkali recovery furnace and the common coal-fired power generation boiler, the current technical situation of the prior art and the actual situation of nitrogen oxide emission, the alkali recovery furnace with the volume of more than 65 tons/hour can be executed according to the emission control requirement of the existing circulating fluidized bed thermal power generation boiler in the emission standard of atmospheric pollutants for thermal power plants (GB 13223-; the alkali recovery furnace of 65 steam tons/hour and below is executed according to the emission control requirement of a biomass briquette boiler in the emission standard of boiler atmospheric pollutants (GB 13271-2014).
According to the letter spirit of the ministry of environmental protection, the alkali recovery furnace execution standard of more than 65 steam tons/hour is as follows: NOx is less than or equal to 200mg/Nm3, SO2 is less than or equal to 200mg/Nm3, and dust is less than or equal to 30mg/Nm 3; the key area executes: NOx is less than or equal to 100mg/Nm3, SO2 is less than or equal to 50mg/Nm3, and dust is less than or equal to 20mg/Nm 3; the alkali recovery furnace execution standard below 65 steam tons/hour is as follows: NOx is less than or equal to 300mg/Nm3, SO2 is less than or equal to 300mg/Nm3, and dust is less than or equal to 50mg/Nm 3; the key area executes: NOx is less than or equal to 200mg/Nm3, SO2 is less than or equal to 200mg/Nm3, and dust is less than or equal to 30mg/Nm 3. Environmental protection departments in various regions can make stricter discharge standards according to local environmental capacity and the actual situation of atmospheric pollution treatment, and some regions even execute the thermal power ultra-low discharge standards, namely: NOx is less than or equal to 50mg/Nm3, SO2 is less than or equal to 35mg/Nm3, and dust is less than or equal to 5mg/Nm 3.
SUMMERY OF THE UTILITY MODEL
In view of the not enough of prior art, the utility model aims to solve the technical problem that a paper industry alkali recovery furnace flue gas denitration dust collector is provided, not only can guarantee nitre, dirt and reach ultralow emission in step, simultaneously because adopt middle and high temperature denitration, can improve denitration efficiency, the live time of extension catalyst improves the stability of device operation.
In order to solve the technical problem, the technical scheme of the utility model is that: a flue gas denitration and dust removal device for an alkali recovery furnace in the papermaking industry comprises a dry electric dust collector, an induced draft fan, a flue gas heat exchanger (GGH), a steam heater, an SCR reactor, a flue gas washing tower, a demister, a wet electric dust collector and a direct exhaust chimney, wherein flue gas comes out of the alkali recovery furnace and enters the dry electric dust collector, a flue gas outlet of the dry electric dust collector is connected with the induced draft fan through a flue, an outlet of the induced draft fan is connected with the flue gas heat exchanger through the flue, the flue gas enters the steam heater after being heated by the flue gas heat exchanger, an outlet of the steam heater is communicated with an inlet of, SCR reactor exit linkage is on gas heater, and the flue gas gets into the flue gas washing tower after gas heater cools off, and the top is provided with the defroster in the flue gas washing tower, and the defroster top is linked together with wet electric dust remover, and the flue gas passes through wet electric dust remover and is discharged by the straight line chimney that sets firmly in wet electric dust remover exit.
Further, an outlet of the induced draft fan is connected with a cold end inlet of the flue gas heat exchanger through a flue, and a hot end outlet of the flue gas heat exchanger is connected with an inlet of the steam heater; and the outlet of the SCR reactor is connected with the hot end inlet of the flue gas heat exchanger, and the cold end outlet of the flue gas heat exchanger is connected with the inlet of the flue gas washing tower.
Furthermore, the flue gas heat exchanger transfers heat for the dividing wall, so that indirect heat exchange between the original flue gas and the purified flue gas is realized, the waste heat of the purified flue gas is effectively utilized, and the energy consumption is greatly reduced.
Furthermore, the dry electric dust collector adopts a multi-electric-field electric dust collector and adopts a high-efficiency high-voltage power supply, so that most of alkali recovery furnace dust can be efficiently removed, and stable operation conditions are created for subsequent denitration and deep dust removal.
Furthermore, the steam heater adopts a tube type heat exchanger, and steam is used for heating the flue gas.
Further, the flue gas washing tower adopts the tower inner loop, is equipped with a plurality of layers of spraying in and is used for washing, sets up the defroster simultaneously, adopts high-efficient defroster, the defroster is the meticulous defogging of multilayer.
Furthermore, a plurality of catalyst layers are arranged in the SCR reactor, a rectifier is arranged above the uppermost catalyst layer, the catalyst layers adopt advanced mature medium-temperature denitration catalysts, the catalyst layers are mature and stable, and ammonium sulfate is prevented from blocking and poisoning the catalysts.
Compared with the prior art, the utility model discloses following beneficial effect has: 1. according to the characteristics of the flue gas and dust of the alkali furnace, the idea of firstly removing dust efficiently, then removing the denitration efficiently and then removing the dust deeply is provided, so that the influence of toxic and harmful substances in the flue gas and dust on the denitration is thoroughly solved, the ultralow emission of the flue gas and NOx is realized, and the long-term stable standard operation of equipment is ensured; 2. the method has the advantages that the discharged clean flue gas is adopted to preheat the denitrated flue gas, so that the heat loss is reduced, and the energy utilization rate and the denitration efficiency of the device are effectively improved; 3. the medium-temperature denitration catalyst is adopted, so that the denitration reaction efficiency is improved, the generation of ammonium sulfate at low temperature is reduced, the catalyst is damaged, the service life of smoke is prolonged, and the operation stability is improved; 4. The process has no waste water, and a small amount of washing water can be recycled to the generating device, so that zero discharge in the true sense is realized.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
In the figure: 100-dry electric dust collector, 200-induced draft fan, 300-flue gas heat exchanger, 400-steam heater, 500-SCR reactor, 501-rectifier, 502-catalyst layer, 600-flue gas washing tower, 601-spraying layer, 602-demister, 700-wet electric dust collector, 800-direct discharge chimney and 900-flue.
Detailed Description
In order to make the aforementioned and other features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
As shown in figure 1, a flue gas denitration dust removal device of a alkali recovery furnace in the paper making industry comprises a dry electric dust collector 100, an induced draft fan 200, a flue gas heat exchanger (GGH) 300, a steam heater 400, an SCR reactor 500, a flue gas washing tower 600, a demister 602, a wet electric dust collector 700 and a direct exhaust chimney 800, wherein flue gas comes out of the alkali recovery furnace and enters the dry electric dust collector, a flue gas outlet of the dry electric dust collector is connected with the induced draft fan through a flue 900, an outlet of the induced draft fan is connected with the flue gas heat exchanger through a flue, the flue gas is heated by the flue gas heat exchanger and then enters the steam heater, an outlet of the steam heater is communicated with an, SCR reactor exit linkage is on gas heater, and the flue gas gets into the flue gas washing tower after gas heater cools off, and the top is provided with the defroster in the flue gas washing tower, and the defroster top is linked together with wet electric dust remover, and the flue gas passes through wet electric dust remover and is discharged by the straight line chimney that sets firmly in wet electric dust remover exit.
This device adopts the process thought of high-efficient dust removal earlier back denitration and degree of depth dust removal again, can guarantee that nitre, dirt reach minimum emission in step, simultaneously because adopt middle and high temperature denitration, can improve denitration efficiency, the live time of extension catalyst improves the stability of device operation.
The denitration reaction principle in the SCR reactor is as follows:
4NO+4NH3+O2 → 4N2+6H2O
2NO2+4NH3+O2 → 3N2+6H2O
in the embodiment of the utility model, the outlet of the induced draft fan is connected with the inlet of the cold end of the flue gas heat exchanger through the flue, and the outlet of the hot end of the flue gas heat exchanger is connected with the inlet of the steam heater; and the outlet of the SCR reactor is connected with the hot end inlet of the flue gas heat exchanger, and the cold end outlet of the flue gas heat exchanger is connected with the inlet of the flue gas washing tower.
The embodiment of the utility model provides an in, gas heater is the dividing wall heat transfer, realizes the indirect heat transfer of former flue gas and clean flue gas, effectively utilizes and purifies the flue gas waste heat, greatly energy saving consumed the festival.
The embodiment of the utility model provides an in, dry electric dust remover adopts many electric fields electrostatic precipitator, and dust collection efficiency is high, and equipment is stable, and the device good reliability, and adopt high-efficient high voltage power supply, guarantee high-efficient desorption most alkali recovery stove dust, create the steady operation condition for follow-up denitration and degree of depth are removed dust.
In the embodiment of the utility model, steam heater adopts shell and tube heat exchanger, utilizes steam to heat the flue gas.
In the embodiment of the utility model, the flue gas washing tower adopts the internal circulation of the tower, a plurality of spraying layers are arranged in the flue gas washing tower for washing, a demister is arranged at the same time, a high-efficiency demister is adopted, and the demister is a multi-layer fine demisting; the flue gas washing tower adopts a wet washing dust removal process, has high dust removal efficiency, stable operation and low failure rate, can change the components of the washing liquid as required, and synchronously realizes ultralow emission of desulfurization and dust removal.
Flue gas scrubbing tower, defroster, wet electric dust remover and direct vent chimney adopt the integration to arrange, save and take up an area of the space, reduce the equipment resistance, reduce flue investment cost.
In the embodiment of the present invention, a plurality of catalyst layers 502 are disposed in the SCR reactor, and a rectifier 501 is disposed above the uppermost catalyst layer, and the catalyst layers are advanced and mature medium-temperature denitration catalysts; through multilayer catalytic denitration, the final denitration efficiency is not lower than 80%, the operation is stable, the economic benefit is good, and the blockage of ammonium sulfate for poisoning the catalyst is avoided.
The embodiment of the utility model provides a theory of operation: (1) flue gas at the outlet of the alkali recovery furnace enters a dry electric dust collector for efficient dust removal, so that dust is controlled in a lower range, and the use requirement of the operation of an SCR reactor on the smoke dust of the alkali recovery furnace is met; (2) after dry electric dust removal, the flue gas led out by a draught fan enters a flue gas heat exchanger and a steam heater to be heated and heated to a temperature higher than 280 ℃; (3) the flue gas after being heated enters an SCR reactor for medium-temperature catalytic denitration; (4) the denitrated clean flue gas enters a flue gas heat exchanger for heat exchange, and is cooled to a proper flue gas temperature; (5) after denitration and temperature reduction, the flue gas enters a flue gas washing tower, is deeply washed, dedusted and demisted, and then enters a wet electric dust remover for further fine dust removal, so that ultra-low emission of dust is ensured; (6) the flue gas after denitration and dust removal can be discharged through an original chimney or a direct discharge chimney arranged at the top of the tower.
The utility model is not limited to the best mode, and anyone can obtain the flue gas denitration dust collector of the alkali recovery furnace in other various forms under the inspiration of the utility model. All the equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims (7)

1. The utility model provides a paper industry alkali recovery furnace flue gas denitration dust collector which characterized in that: including dry electric dust collector, draught fan, gas heater, steam heater, SCR reactor, flue gas scrubbing tower, defroster, wet electric dust collector and direct vent chimney, the flue gas comes out from alkali recovery furnace, gets into dry electric dust collector, and dry electric dust collector exhanst gas outlet passes through the flue and connects the draught fan, and the draught fan export is linked together through flue and gas heater, and the flue gas gets into steam heater after the heating of gas heater, and the steam heater export communicates with each other with SCR reactor entry, SCR reactor exit linkage is on gas heater, and the flue gas gets into the flue gas scrubbing tower after the cooling of gas heater, and the top is provided with the defroster in the flue gas scrubbing tower, and the defroster top is linked together with wet electric dust collector, and the flue gas passes through wet electric dust collector and is discharged by the direct vent chimney that sets firmly in wet electric dust collector exit.
2. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry according to claim 1, which is characterized in that: the outlet of the induced draft fan is connected with the cold end inlet of the flue gas heat exchanger through a flue, and the hot end outlet of the flue gas heat exchanger is connected with the inlet of the steam heater; and the outlet of the SCR reactor is connected with the hot end inlet of the flue gas heat exchanger, and the cold end outlet of the flue gas heat exchanger is connected with the inlet of the flue gas washing tower.
3. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry as claimed in claim 2, is characterized in that: the flue gas heat exchanger transfers heat for the dividing wall, and realizes indirect heat exchange of the original flue gas and the purified flue gas.
4. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry according to claim 1, which is characterized in that: the dry electric dust collector adopts a multi-electric-field electric dust collector and adopts a high-efficiency high-voltage power supply, so that most of alkali recovery furnace dust is efficiently removed, and stable operation conditions are created for subsequent denitration and deep dust removal.
5. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry according to claim 1, which is characterized in that: the steam heater adopts a tube type heat exchanger and utilizes steam to heat the flue gas.
6. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry according to claim 1, which is characterized in that: the flue gas washing tower adopts the tower inner loop, is equipped with a plurality of layers that spray in and is used for washing, still sets up the defroster in the flue gas washing tower, adopts high-efficient defroster, the defroster is the meticulous defogging of multilayer.
7. The flue gas denitration and dust removal device for the alkali recovery furnace in the paper making industry according to claim 1, which is characterized in that: and a plurality of catalyst layers are arranged in the SCR reactor, and a rectifier is arranged above the uppermost catalyst layer.
CN202020228232.3U 2020-02-28 2020-02-28 Flue gas denitration and dust removal device for alkali recovery furnace in papermaking industry Active CN211936384U (en)

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CN202020228232.3U CN211936384U (en) 2020-02-28 2020-02-28 Flue gas denitration and dust removal device for alkali recovery furnace in papermaking industry

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111111440A (en) * 2020-02-28 2020-05-08 福建鑫泽环保设备工程有限公司 Flue gas denitration and dust removal device and process for alkali recovery furnace in papermaking industry

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111111440A (en) * 2020-02-28 2020-05-08 福建鑫泽环保设备工程有限公司 Flue gas denitration and dust removal device and process for alkali recovery furnace in papermaking industry

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