CN112495142A - System and method for removing pollutants in flue gas collected by sodium sulfide removal thermosol tank - Google Patents
System and method for removing pollutants in flue gas collected by sodium sulfide removal thermosol tank Download PDFInfo
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- CN112495142A CN112495142A CN202011372176.1A CN202011372176A CN112495142A CN 112495142 A CN112495142 A CN 112495142A CN 202011372176 A CN202011372176 A CN 202011372176A CN 112495142 A CN112495142 A CN 112495142A
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- 239000003546 flue gas Substances 0.000 title claims abstract description 186
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 182
- 229910052979 sodium sulfide Inorganic materials 0.000 title claims abstract description 52
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000003344 environmental pollutant Substances 0.000 title claims abstract description 43
- 231100000719 pollutant Toxicity 0.000 title claims abstract description 43
- 239000007788 liquid Substances 0.000 claims abstract description 95
- 239000007789 gas Substances 0.000 claims abstract description 57
- 238000005406 washing Methods 0.000 claims abstract description 57
- 239000007921 spray Substances 0.000 claims abstract description 39
- 239000000428 dust Substances 0.000 claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000000926 separation method Methods 0.000 claims abstract description 19
- 238000002844 melting Methods 0.000 claims abstract description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 86
- 239000003513 alkali Substances 0.000 claims description 49
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 31
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims description 31
- 239000000779 smoke Substances 0.000 claims description 15
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims description 14
- 230000008018 melting Effects 0.000 claims description 13
- 238000005201 scrubbing Methods 0.000 claims description 12
- 239000003595 mist Substances 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 6
- 238000006460 hydrolysis reaction Methods 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000012958 reprocessing Methods 0.000 claims description 4
- 238000011268 retreatment Methods 0.000 claims description 4
- 238000005070 sampling Methods 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 239000000356 contaminant Substances 0.000 claims description 2
- 238000012545 processing Methods 0.000 claims description 2
- 239000003518 caustics Substances 0.000 claims 1
- 230000007547 defect Effects 0.000 abstract description 2
- 238000011044 inertial separation Methods 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 10
- 238000005507 spraying Methods 0.000 description 10
- 238000002386 leaching Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 3
- 241000565357 Fraxinus nigra Species 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000019086 sulfide ion homeostasis Effects 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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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
- B01D53/14—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 by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
-
- 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
- B01D47/06—Spray cleaning
-
- 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
- B01D53/14—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 by absorption
- B01D53/1456—Removing acid components
- B01D53/1468—Removing hydrogen sulfide
-
- 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
- B01D53/26—Drying gases or vapours
- B01D53/263—Drying gases or vapours by absorption
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention relates to a system and a method for removing pollutants in flue gas collected by a sodium sulfide hot-melting tank, wherein the flue gas collected by the sodium sulfide hot-melting tank is conveyed to a flue gas washing tower, the washing liquid is in strong and sufficient contact with the flue gas in a reverse spray pipe of the washing tower, so that the pollutants in the flue gas are absorbed or dissolved by circulating liquid, and the washed flue gas is subjected to settling separation in a gas-liquid separation region and inertial separation of a baffle plate and a complex baffle plate in sequence to remove particulate matters (including water drops and dust) carried by the flue gas, thereby realizing clean emission of tail gas. The method and the system can efficiently remove the pollutants in the flue gas collected by the sodium sulfide thermosol tank, solve the obvious defects of the traditional removing device, improve the field environment of the sodium sulfide thermosol operation, improve the safety of the sodium sulfide thermosol operation and realize the standard emission of the pollutants in the flue gas.
Description
Technical Field
The invention relates to treatment of circularly collected smoke pollutants (alkali fog, hydrogen sulfide gas, dust and water vapor) of a thermosol tank, in particular to a treatment method and a treatment system for circularly collected smoke pollutants of a thermosol tank in industries of removing sodium sulfide, sodium hydrosulfide and the like by using an alkali liquor absorption technology.
Background
The alkali dissolving and leaching of the clinker in the production process of the sodium sulfide are necessary procedures in the production process of the sodium sulfide. In the production process of sodium sulfide, clinker (or black ash) discharged from a sodium sulfide (namely sodium sulfide) calcining furnace is naturally cooled to 700-750 ℃, then the clinker or black ash is sent into a sodium sulfide hot melting tank, a conversion agent is added at the same time for leaching, flue gas and water vapor dissipated by the hot melting tank are collected and then sent to an absorption tower for treatment, dilute sodium sulfide solution is adopted to spray and absorb pollutants (alkali mist, hydrogen sulfide gas, dust and water vapor) in the flue gas collected by a ring, and absorption liquid returns to the hot melting tank for alkali dissolution.
The treatment method for collecting the smoke pollutants by adopting the dilute sodium sulfide solution spraying absorption ring has the following defects: it is difficult to ensure effective removal of contaminants (especially a small amount of hydrogen sulfide gas), and safety and environmental pollution accidents are easy to occur. The absorption process described above mainly suffers from the following two drawbacks: (1) in the absorption process, the temperature of the dilute sodium sulfide solution is high, and if the dosage and concentration of the absorption solution are improperly controlled, the dilute alkali sulfide solution is difficult to effectively absorb pollutants such as hydrogen sulfide, sodium hydrosulfide and the like; (2) the density of the absorption liquid is large, and under the condition of large spraying amount, the surrounding of the hot melting tank (especially a liquid outlet) is often caused, the smoke is diffused, the operation environment is severe, and the potential safety hazard is large.
Disclosure of Invention
Therefore, in order to solve the safety and environmental protection problems of flue gas pollutants (alkali mist, hydrogen sulfide gas, dust and water vapor) escaping from the hot melting tank in the production process of sodium sulfide, the method for removing the pollutants in the flue gas circularly collected by the hot melting tank of sodium sulfide is provided, and the safety of sodium sulfide production is improved.
After long-term research, the inventor of the invention finds that the problems can be solved by utilizing the characteristics that sodium sulfide, sodium hydrosulfide and hydrogen sulfide are easily absorbed by a sodium hydroxide solution and are difficult to hydrolyze under an alkaline condition and removing smoke pollutants in a sodium sulfide hot melting tank ring by adopting a strong gas-liquid contact mode.
The sodium hydroxide solution with lower concentration is selected as an absorbent, a reverse spraying mode of strong gas-liquid contact is adopted, the flue gas pollutants escaping from the sodium sulfide thermosol are removed by utilizing the technical principle of inertial settling of liquid drops and dust, and the problems of environmental pollution and potential safety hazard in the process of thermosol of the sodium sulfide are solved.
The invention provides a system for removing pollutants in circularly collected flue gas of a sodium sulfide hot melting tank, which is characterized by comprising a gas collection part, a washing part, a retreatment part and a tail gas emission part, wherein the gas collection part, the washing part, the retreatment part and the tail gas emission part are sequentially connected through a pipeline.
Preferably, in the above removal system, the gas collecting part is provided with a gas collecting hood and an induced draft fan, the washing part is provided with a flue gas washing tower, an alkali liquor circulating pump and an alkali liquor adding pump, the reprocessing part is provided with a complex baffle demister, and the tail gas discharging part is provided with a tail gas discharging chimney; the gas collecting channel passes through the pipeline with the draught fan and links to each other, be provided with contrary spray tube on the flue gas scrubbing tower, the draught fan passes through the pipeline with contrary spray tube and links to each other, the alkali lye circulating pump passes through the pipeline with the flue gas scrubbing tower and links to each other, the tail gas emission chimney sets up after compound baffle demister, compound baffle demister passes through the pipeline with the flue gas scrubbing tower and links to each other, alkali lye adds the pump and passes through the pipeline with the flue gas scrubbing tower and links to each other.
Preferably, in the above removal system, two or more gas collecting hoods are provided.
Preferably, in the above removal system, an atomizing nozzle is disposed in the reverse spraying pipe.
Preferably, in the above removal system, the lye circulating pump is connected to the atomizing nozzle in the reverse spray pipe through a pipe.
Preferably, in the above removing system, the lye circulating pump is connected to the circulating tank of the flue gas scrubbing tower through a pipeline.
Preferably, in the above removal system, a baffle plate demister is further disposed in the flue gas scrubbing tower, and the baffle plate demister may be of the same plate type or a combination of different plate types.
Preferably, the above removal system, wherein the system is further provided with a flush pump connected to the upper part of the baffled demister in the flue gas scrubbing tower through a pipe.
Preferably, in the above removal system, the bottom of the multiple baffle demister is connected to the circulation tank of the flue gas scrubbing tower through a pipeline.
Preferably, in the above removal system, the exhaust emission chimney is further provided with a monitoring sampling point.
Preferably, in the above removing system, the lye addition pump is further connected with a lye configuration tank.
Preferably, in the above removing system, the alkali solution is sodium hydroxide solution, and the pH value thereof is 7.5-9.
The invention also provides a method for removing pollutants in the circularly collected flue gas of the sodium sulfide thermosol tank by using the removing system, which is characterized by comprising the following steps:
step 1: the gas collecting part collects the ring-shaped smoke gas escaping from the sodium sulfide thermosol tank,
step 2: the pollutants in the ring-collected flue gas are washed and absorbed by the washing part,
and step 3: the reprocessing part is used for processing the circularly collected flue gas and then discharging the processed circularly collected flue gas through the tail gas discharging part.
Preferably, the method according to above, wherein the pollutants in the ring-collected flue gas comprise alkali mist, hydrogen sulfide gas, dust and water vapor.
Preferably, according to the method, the collected flue gas in the step 1 is pumped by a draught fan through a gas collecting hood and is conveyed to a flue gas washing tower.
Preferably, the method according to the above, wherein the collected flue gas in step 2 is fully contacted with the alkali liquor in the back spray pipe of the flue gas washing tower and absorbed or dissolved.
Preferably, in the method, in step 3, the tail gas is subjected to a baffled demister and a baffle demister to remove particles and liquid drops entrained by the collected flue gas.
Preferably, the method is implemented, wherein the vacuum degree of the area in the edge of the gas collecting hood is greater than or equal to 100Pa, so that the annular smoke on the hot melting tank is completely sucked and conveyed into the smoke washing tower.
Preferably, according to the method, in step 2, the circularly collected flue gas containing the pollutants enters a reverse spray pipe of a flue gas washing tower from top to bottom, the alkali circulation liquid is sprayed out from an atomizing nozzle, a conical water mist curtain is formed by centrifugal rotation inside the nozzle, the atomized alkali circulation liquid rises to the highest point of a washing pipe and falls, the atomized alkali circulation liquid is in strong and sufficient contact with the flue gas, the alkali circulation liquid absorbs hydrogen sulfide and sodium hydrosulfide in the flue gas to generate sodium sulfide, the sodium sulfide is dissolved in the alkali circulation liquid and is difficult to undergo hydrolysis reaction, so that the removal of the hydrogen sulfide and sodium hydrosulfide in the flue gas is realized, and the wet flue gas (containing liquid droplets) which is washed and absorbed by the alkali circulation liquid enters a gas-liquid separation area of the washing tower.
Preferably, according to the above method, in step 2, in the gas-liquid separation area of the flue gas washing tower, the flow velocity of the flue gas is rapidly reduced, most of the liquid drops and dust are settled and separated from the flue gas, and the flue gas passes through the two layers of baffle plate demister arranged at the top to remove most of the liquid drops and dust in the flue gas, and then enters the multiple baffle plate demister.
Preferably, according to the method, in step 3, the flue gas is treated again by the baffle demister to remove fine liquid drops and dust, so that clean emission of pollutants in the flue gas is realized.
Preferably, according to the method, the flow velocity (space velocity) of the flue gas in the reverse spray pipe is 15-25 m/s; the temperature of the flue gas entering the reverse spray pipe of the flue gas washing tower is less than or equal to 120 ℃, and the circulating liquid of the reverse spray pipe circulating liquid atomizing spray headThe pressure (gauge pressure) is 80-120 kPa; the liquid/gas ratio in the reverse spraying pipe is 5-10L/m3。
Preferably, the method is characterized in that the flow velocity of the flue gas in the separation area of the flue gas washing tower (3) is 0.5-1.5 m/s, preferably 0.5-0.8 m/s;
or further preferably, the residence time of the flue gas is 5-12 s;
or further preferably, the operation pH range of the alkali circulating liquid is 7.5-9.0;
or further preferably, the density range controlled by the circulating liquid in the operation of the washing tower is 1.02-1.15 t/m3More preferably 1.05 to 1.08t/m3。
Preferably, according to the above method, wherein the alkali circulating liquid is a sodium hydroxide solution.
The beneficial effects of the invention include:
the method for removing the pollutants in the circularly collected flue gas of the sodium sulfide hot melting tank can avoid the escape of the pollutants in the flue gas in the process of leaching sodium sulfide, collects circularly collected flue gas containing the pollutants such as hydrogen sulfide, sodium hydrosulfide and the like, sends the circularly collected flue gas into the flue gas washing reaction tower, converts the removed hydrogen sulfide and sodium hydrosulfide into sodium sulfide, realizes effective gas-liquid separation, ensures the clean emission of the discharged flue gas, and eliminates the potential safety hazard of the escape of the pollutants such as the hydrogen sulfide and the like in the process of leaching sodium sulfide.
Sulfide (converted into H) in treated discharged flue gas2S) content is less than or equal to 5mg/m3The water drop content is less than or equal to 50mg/m3The dust content is less than or equal to 10mg/m3. Controlling the pH operation range of the circulating liquid of the washing tower, replenishing alkali liquor in due time, ensuring the absorption capacity of the circulating liquid to pollutants such as hydrogen sulfide, alkali fog and the like, and concentrating and recycling salt.
The invention and its advantageous technical effects are explained in detail below with reference to the accompanying drawings and various embodiments, in which:
drawings
FIG. 1 is a schematic diagram of the method and system of the present invention;
1-gas collecting hood 2-draught fan 3-flue gas scrubbing tower 4-compound baffle demister 5-tail gas discharge chimney 6-monitoring sampling point 7-alkali liquor circulating pump 8-alkali liquor adding pump 9-flushing pump 10-alkali liquor preparation tank 11-reverse spray pipe 12-atomizer spray head 13-pH analyzer 14-gas-liquid separation area 15-first gas pressure gauge 16-second gas pressure gauge 17-baffle demister.
Detailed Description
As described above, the present invention aims to solve the safety and environmental protection problems of flue gas pollutants (alkali mist, hydrogen sulfide gas, dust and water vapor) escaping from a hot melting tank during the production process of sodium sulfide, and provides a method for removing pollutants in flue gas circularly collected by the hot melting tank of sodium sulfide, so as to improve the safety of sodium sulfide production.
The purpose of the invention is realized by the following technical scheme.
A method for removing pollutants in circularly collected flue gas of a sodium sulfide thermosol tank is characterized by comprising the following steps:
firstly, a gas-collecting hood 1 is arranged on a sodium sulfide thermosol, pollutants (alkali fog, hydrogen sulfide gas, dust and water vapor) escaping from the sodium sulfide thermosol are sucked and collected by an induced draft fan 2 and are conveyed to a flue gas washing tower 3.
Secondly, the ring-collected flue gas containing pollutants is in strong and sufficient contact with the cleaning solution in the reverse spray pipe 11 of the flue gas washing tower 3, so that sodium sulfide, sodium hydrosulfide and hydrogen sulfide are absorbed or dissolved in the sodium hydroxide solution, meanwhile, inert dust is wetted and particulate matters with larger particle sizes are generated, then the flue gas enters a gas-liquid separation area 14 of the flue gas washing tower 3 to realize settling separation of liquid drops and dust, and finally the tail gas passes through a baffle plate demister 17 and a double baffle plate demister 4 to remove the particulate matters (including the liquid drops and the dust) carried by the flue gas, thereby realizing clean emission of the tail gas.
On the basis of the technical scheme, the method specifically comprises the following steps:
(1) arranging a gas-collecting hood 1 on a sodium sulfide thermosol tank, and sucking by using a draught fan 2 to ensure that the vacuum degree (or called negative pressure) of an area in the edge of the gas-collecting hood 1 reaches 100Pa, so that all circularly collected flue gas on the thermosol tank is sucked and conveyed into a flue gas washing tower 3;
(2) the circularly collected flue gas containing pollutants enters a reverse spray pipe 11 of a flue gas washing tower 3 from top to bottom, sodium hydroxide circulating liquid is sprayed out from an atomizing spray head 12 and centrifugally rotates in the spray head under high pressure to form a conical water mist curtain, the atomized circulating liquid rises to the highest point of the reverse spray pipe 11 and then falls down, the atomized sodium hydroxide circulating liquid is in strong and sufficient contact with the flue gas, the sodium hydroxide solution absorbs hydrogen sulfide and sodium hydrosulfide in the flue gas to generate sodium sulfide, the sodium sulfide is dissolved in the sodium hydroxide solution and is difficult to perform hydrolysis reaction, so that the removal of the hydrogen sulfide and the sodium hydrosulfide in the flue gas is realized, and the wet flue gas (containing liquid drops) which is washed and absorbed by the sodium hydroxide circulating liquid enters a gas-liquid separation area 14 of the flue gas washing tower 3;
(3) in a gas-liquid separation area 14 of the flue gas washing tower 3, the flow velocity of flue gas is rapidly reduced, most of liquid drops and dust are settled and separated from the flue gas, the flue gas passes through a two-layer baffle plate demister 17 arranged at the top to remove most of liquid drops and dust in the flue gas, and then enters a double-baffle plate demister 4;
(4) the flue gas is treated again by the complex baffle demister 4 to remove fine liquid drops and dust, thereby realizing the clean emission of pollutants in the flue gas.
On the basis of the technical scheme, the sulfide (converted into H) in the treated discharged flue gas2S) content is less than or equal to 5mg/m3The water drop content is less than or equal to 50mg/m3The dust content is less than or equal to 10mg/m3. The pH operation range of the alkali circulating liquid in the flue gas washing tower 3 is controlled, the alkali circulating liquid is supplemented timely, the absorption capacity of the alkali circulating liquid on pollutants such as hydrogen sulfide, alkali mist and the like is ensured, and salt can be concentrated and recycled.
On the basis of the technical scheme, the flow speed of the flue gas in the reverse spraying pipe 11 is as follows: 15-25 m/s;
on the basis of the technical scheme, the circulating liquid pressure (gauge pressure) of the alkali circulating liquid spray head in the reverse spray pipe 11 is as follows: 80-120 kPa;
on the basis of the technical scheme, the liquid/gas ratio in the reverse spraying pipe 11 is as follows: 5 to 10L/m3；
On the basis of the above technical solution, the flue gas flow rate (space velocity) of the gas-liquid separation region 14 in the flue gas scrubber 3: 0.5 to 1.5 m/s;
on the basis of the above technical solution, the residence time of the flue gas in the gas-liquid separation region 14 in the flue gas washing tower 3 is as follows: 5-12 s;
on the basis of the technical scheme, the temperature of the flue gas entering the reverse spray pipe 11 of the flue gas washing tower 3 is less than or equal to 120 ℃;
on the basis of the technical scheme, the operation pH range of the alkali circulating liquid in the flue gas washing tower 3 is as follows: 7.5 to 9.0;
on the basis of the technical scheme, the density range of the alkali circulating liquid in the flue gas washing tower 3 is controlled as follows: 1.02-1.15 t/m3。
The method for removing the hydrogen sulfide escaped from the sodium sulfide leaching tank mainly comprises the following equipment: the device comprises a gas collecting hood 1, a draught fan 2, a flue gas washing tower 3, a double-baffle demister 4, a tail gas discharge chimney 5, a reverse spray pipe 11, an atomizing nozzle 12, a gas-liquid separation area 14 and a baffle demister 17.
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1: method for removing pollutants in ring-collected flue gas
Step 1: arranging a gas-collecting hood 1 on a sodium sulfide thermosol tank, and sucking by using a draught fan 2 to ensure that the vacuum degree (or called negative pressure) of an area in the edge of the gas-collecting hood reaches 100Pa, so that all the circularly collected flue gas on the thermosol tank is sucked and conveyed into a flue gas washing tower 3;
step 2: the circularly collected flue gas containing pollutants enters a reverse spray pipe 11 of a washing tower from top to bottom, sodium hydroxide circulating liquid is pressurized by an alkali liquor circulating pump 7, then is sprayed out by an atomizing spray head 12, centrifugally rotates in the spray head under high pressure to form a conical water mist curtain, the atomized circulating liquid rises to the highest point of the reverse spray pipe 11 and then falls, the atomized circulating liquid is in strong and sufficient contact with the flue gas, the sodium hydroxide circulating liquid absorbs hydrogen sulfide and sodium hydrosulfide in the flue gas to generate sodium sulfide, the sodium sulfide is dissolved in the sodium hydroxide solution and is difficult to perform hydrolysis reaction, so that the removal of the hydrogen sulfide and the sodium hydrosulfide in the flue gas is realized, and the wet flue gas (containing liquid drops) which is washed and absorbed by the sodium hydroxide circulating liquid enters a gas-liquid separation area 14 of the flue gas washing tower 3;
and step 3: in a gas-liquid separation area 14 of the flue gas washing tower 3, the flow velocity of flue gas is rapidly reduced, most of liquid drops and dust are settled and separated from the flue gas, the flue gas passes through a two-layer baffle plate demister 17 arranged at the top to remove most of liquid drops and dust in the flue gas, and then enters a double-baffle plate demister 4; the flue gas is treated again by the complex baffle demister 4 to remove fine liquid drops and dust, and is discharged from a tail gas discharge chimney 5, so that the clean discharge of pollutants in the flue gas is realized, and the pollutants in the discharged flue gas can be sampled and analyzed by a monitoring (or detection) sampling point 6.
And 4, step 4: in the operation of the system, the on-line pH analyzer 13 detects the pH of the circulating liquid. If the pH value of the circulating liquid is lower than the lower control limit, starting an alkali liquor adding pump 8, and adding a sodium hydroxide solution into a circulating groove at the lower part of the flue gas washing tower 3 from an alkali liquor preparation groove 10; if the pH of the circulating solution is higher than the upper limit of control, the sodium hydroxide solution addition pump 8 is stopped.
And 5: in the operation of the system, the operation resistance of the baffle plate demister 17 is detected by a first gas pressure gauge 15 and a second gas pressure gauge 16, and if the operation resistance of the baffle plate demister 17 (the pressure numerical difference between the gauge 15 and the gauge 16) reaches 500Pa, the flushing pump 9 is started to flush the baffle plate demister 17 and remove the salt crystallized on the plate; if the running resistance of the baffle plate demister does not reach 500Pa in 12 hours, the washing pump 9 is started to wash the baffle plate demister 17, remove the salt crystallized on the baffle plate and ensure that the baffle plate demister 17 is smooth.
Example 2
The flue gas conditions entering the scrubber were as follows: flue gas flow 45000Nm3The dust concentration in the flue gas is 65mg/Nm3The concentration of hydrogen sulfide in the flue gas is 15mg/Nm3The water content in the smoke is 48g/Nm3The flue gas temperature is 65 ℃, and the circulating liquid spraying amount of the washing tower is 230m3H, the pH value of the circulating liquid is controlled to be 7.2 +/-0.5, and the density of the circulating liquid of the washing tower is about 1.03t/m3。
The removal was carried out by the procedure described above in example 1.
After treatment, the detection data of the discharged flue gas are as follows: a flow rate of45200Nm3The dust concentration in the flue gas is 5mg/Nm3The concentration of hydrogen sulfide in the flue gas is 3mg/Nm3The water content in the smoke is 50g/Nm3The flue gas temperature was 45 ℃.
Example 3
The flue gas conditions entering the scrubber were as follows: flue gas flow rate 35000Nm3The dust concentration in the flue gas is 80mg/Nm3The concentration of hydrogen sulfide in the flue gas is 21mg/Nm3The water content in the smoke is 52g/Nm3The flue gas temperature is 72 ℃, and the circulating liquid spraying amount of the washing tower is 210m3H, the pH value of the circulating liquid is controlled to be 7.5 +/-0.5, and the density of the circulating liquid of the washing tower is about 1.05t/m3。
The removal was carried out by the procedure described above in example 1.
After treatment, the detection data of the discharged flue gas are as follows: the flow rate was 35600Nm3The dust concentration in the flue gas is 3mg/Nm3The concentration of hydrogen sulfide in the flue gas is 2mg/Nm3The water content in the smoke is 46g/Nm3The flue gas temperature was 43 ℃.
Example 4
The flue gas conditions entering the scrubber were as follows: flue gas flow 52000Nm3The dust concentration in the flue gas is 76mg/Nm3The concentration of hydrogen sulfide in the flue gas is 14mg/Nm3The water content in the smoke is 38g/Nm3The flue gas temperature is 58 ℃, and the circulating liquid spraying amount of the washing tower is 280m3H, the pH value of the circulating liquid is controlled to be 7.8 +/-0.5, and the density of the circulating liquid of the washing tower is about 1.10t/m3。
The removal was carried out by the procedure described above in example 1.
After treatment, the detection data of the discharged flue gas are as follows: the flow rate was 52300Nm3The dust concentration in the flue gas is 2mg/Nm3The concentration of hydrogen sulfide in the flue gas is 2mg/Nm3Water content in smoke 42g/Nm3The temperature of the flue gas is 41 ℃.
The foregoing is considered as illustrative and not restrictive in character, and that various modifications, equivalents, and improvements made within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (24)
1. The system for removing pollutants in the circularly collected flue gas of the sodium sulfide hot melting tank is characterized by comprising a gas collecting component, a washing component, a retreatment component and a tail gas emission component, wherein the gas collecting component, the washing component, the retreatment component and the tail gas emission component are sequentially connected through a pipeline.
2. The removal system of claim 1, wherein the gas collection component is provided with a gas collection hood (1) and an induced draft fan (2), the scrubbing component is provided with a flue gas scrubbing tower (3), a lye circulating pump (7) and a lye addition pump (8), the reprocessing component is provided with a double baffle demister (4), and the tail gas emission component is provided with a tail gas emission chimney (5);
gas collecting channel (1) links to each other through the pipeline with draught fan (2), be provided with contrary spray tube (11) on flue gas washing tower (3), draught fan (2) link to each other through the pipeline with contrary spray tube (11), alkali lye circulating pump (7) link to each other through the pipeline with flue gas washing tower (3), tail gas emission chimney (5) set up after baffle demister (4) again, baffle demister (4) again links to each other through the pipeline with flue gas washing tower (3), alkali lye adds pump (8) and flue gas washing tower (3) and passes through the pipeline and links to each other.
3. Stripping system according to claim 1 or 2, wherein more than two gas headers (1) are provided.
4. Stripping system according to any one of claims 1-3, wherein an atomising spray head (12) is arranged in the counter nozzle (11).
5. Stripping system according to any one of claims 1 to 4, wherein the lye circulating pump (7) is connected by a pipe to an atomising spray head (12) in the counter spray pipe (11).
6. Stripping system according to any one of claims 1 to 5, wherein the lye circulation pumps (7) are connected by a pipe to the circulation tank of the flue gas scrubber (3).
7. A stripping system according to any one of claims 1 to 6, wherein a baffled demister (17) is further provided in the flue gas scrubbing tower (3), and the baffled demister (17) can be of the same plate type or a combination of different plate types.
8. A stripping system according to any one of claims 1-7, wherein the system is further provided with a flush pump (9), which flush pump (9) is connected by a pipe to the upper part of the baffled demister (17) in the flue gas scrubber tower (3).
9. Stripping system according to any one of claims 1 to 8, wherein the bottom of the multiple baffle demister (4) is connected to the circulation tank of the flue gas scrubber tower (3) by a pipe.
10. A removal system according to any one of claims 1-9, wherein a monitoring sampling point (6) is further provided on the off-gas emission stack (5).
11. Stripping system according to any one of claims 1-10, wherein a lye allocation tank (10) is further connected to the lye addition pump (8).
12. Stripping system according to any one of claims 1 to 11, wherein the lye is a sodium hydroxide liquor having a pH value of 7.5 to 9.
13. A method for removing pollutants in the flue gas of the sodium sulfide thermosol ring collection by using the removing system of any one of claims 1 to 12, which is characterized by comprising the following steps:
step 1: the gas collecting part collects the ring-shaped smoke gas escaping from the sodium sulfide thermosol tank,
step 2: the pollutants in the ring-collected flue gas are washed and absorbed by the washing part,
and step 3: the reprocessing part is used for processing the circularly collected flue gas and then discharging the processed circularly collected flue gas through the tail gas discharging part.
14. The method of claim 13, wherein the contaminants in the ring-collected flue gas include alkali fog, hydrogen sulfide gas, dust, and water vapor.
15. The method according to claim 13 or 14, wherein the collected flue gas in step 1 is pumped by the gas-collecting hood (1) through the induced draft fan (2) and conveyed to the flue gas scrubber (3).
16. The method according to any one of claims 13-15, wherein the collected flue gas in step 2 is brought into full contact with the lye and is absorbed or dissolved in the backwash tower (11) of the flue gas scrubber (3).
17. The method according to any one of claims 13 to 16, wherein in step 3, the tail gas is subjected to a baffle demister (17) and a multiple baffle demister (4) to remove particles and liquid drops entrained by the circularly collected flue gas.
18. A method according to any of claims 13-17, wherein the vacuum level in the area inside the edge of the gas hood (1) is greater than or equal to 100Pa, so that the ring-collected flue gases on the thermosol can are all sucked and transported into the flue gas scrubber (3).
19. The method according to any one of claims 13 to 18, wherein in the step 2, the circularly collected flue gas containing the pollutants enters a reverse spray pipe (11) of the flue gas washing tower (3) from top to bottom, the alkali circulation liquid is sprayed out from an atomizing spray head (12), a conical water mist curtain is formed by centrifugal rotation inside the spray head, the atomized alkali circulation liquid rises to the highest point of the reverse spray pipe (11) and then falls, the atomized alkali circulation liquid is in strong and sufficient contact with the flue gas, the alkali circulation liquid absorbs hydrogen sulfide and sodium hydrosulfide in the flue gas to generate sodium sulfide, the sodium sulfide is dissolved in the alkali circulation liquid and is difficult to perform hydrolysis reaction, so that the removal of the hydrogen sulfide and sodium hydrosulfide in the flue gas is realized, and the wet flue gas (containing liquid drops) which is washed and absorbed by the alkali circulation liquid enters a gas-liquid separation area (14) of the washing tower.
20. The method according to any one of claims 13 to 19, wherein in the step 2, in the gas-liquid separation area (14) of the flue gas washing tower (3), the flow velocity of the flue gas is rapidly reduced, most of liquid drops and dust are settled and separated from the flue gas, and the flue gas passes through a two-layer baffle demister (17) arranged at the top to remove most of liquid drops and dust in the flue gas and then enters the double-baffle demister (4).
21. A method according to any of claims 13-20, wherein in step 3 the flue gas is treated again by means of a repeated baffle demister (4) to remove fine droplets and dust, thereby achieving clean emission of pollutants in the flue gas.
22. A method according to any one of claims 13-21, wherein the flue gas velocity (space velocity) inside the backspraying pipe (11) is 15-25 m/s; the temperature of the flue gas entering a reverse spray pipe (11) of the flue gas washing tower (3) is less than or equal to 120 ℃, and the circulating liquid pressure (gauge pressure) of a circulating liquid atomizing spray head (12) of the reverse spray pipe (11) is 80-120 kPa; the liquid/gas ratio in the reverse spray pipe (11) is 5-10L/m3。
23. A method according to any one of claims 13-22, wherein the flue gas velocity in the separation zone of the flue gas scrubber (3) is 0.5-1.5 m/s, preferably 0.5-0.8 m/s;
or further preferably, the residence time of the flue gas is 5-12 s;
or further preferably, the operation pH range of the alkali circulating liquid is 7.5-9.0;
or further preferably the density range of the circulating liquid for the operation of the washing tower is controlled to be 1.02-1.15 t/m3, and more preferably 1.05-1.08 t/m3。
24. The process of any one of claims 13-23, wherein the caustic recycle liquor is a sodium hydroxide solution.
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