CN111450678B - Method and device for purifying waste gas containing chlorine or/and sulfur to obtain byproduct ammonium salt - Google Patents
Method and device for purifying waste gas containing chlorine or/and sulfur to obtain byproduct ammonium salt Download PDFInfo
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- CN111450678B CN111450678B CN202010264544.4A CN202010264544A CN111450678B CN 111450678 B CN111450678 B CN 111450678B CN 202010264544 A CN202010264544 A CN 202010264544A CN 111450678 B CN111450678 B CN 111450678B
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- 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
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- 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
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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
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/58—Ammonia
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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
- B01D53/46—Removing components of defined structure
- B01D53/68—Halogens or halogen compounds
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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
- B01D53/76—Gas phase processes, e.g. by using aerosols
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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
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/16—Halides of ammonium
- C01C1/164—Ammonium chloride
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/22—Sulfites of ammonium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Abstract
A method for purifying by-product ammonium salt from waste gas containing chlorine or/and sulfur and its device, using gas containing ammonia as purifying agent, mixing and purifying the purifying agent and the gas containing chlorine or/and sulfur to convert all chlorine and sulfur into ammonium salt, circularly spraying and trapping ammonium salt smoke generated in the purifying process with water, directly obtaining ammonium salt crystal by liquid-solid separation without evaporation and crystallization, returning filtrate to a spraying system for recycling, and trapping residual ammonia in purified tail gas with weak acid solution to discharge after reaching standards.
Description
Technical Field
The invention belongs to the field of metallurgical chemical industry, and particularly relates to a method and a device for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt.
Background
The chlorine-containing waste gas generated in the metallurgical and chemical industries usually contains HCl or/and Cl 2 And small amounts of metal and non-metal chloride gases, e.g. TiCl 4 、SiCl 4 、AlCl 3 、FeCl 3 Chlorine-containing waste gases are harmful to industrial equipment and ecological environment and must be purified.
Method for purifying chlorine-containing waste gasMainly, there are a condensation method, a water absorption method, a neutralization absorption method, and the like. The condensation method is to send high-concentration HCl waste gas into a graphite condenser for condensation and recovery of hydrochloric acid, and the waste gas after condensation and recovery of hydrochloric acid is absorbed by water. The condensation method can only remove about 90% of HCl in the waste gas. The water absorption method is to send the waste gas containing high-concentration HCl into an absorption tower, the HCl in the waste gas is absorbed by water spraying countercurrent contact, and the purified tail gas reaches the standard and is discharged. The condensation method and the water absorption method can only absorb HCl in the waste gas, but are difficult to absorb Cl in the waste gas 2 And removing the wastewater which reaches the standard and is discharged. The neutralization absorption method is to use alkaline liquor or lime milk as an absorbent to absorb HCl and Cl in the waste gas 2 However, the obtained absorbed liquid contains hypochlorite, which is harmful to the ecological environment.
To avoid the formation of hypochlorite-containing solutions, Cl is contained 2 The exhaust gas is usually treated by a redox method or a solvent absorption method. The oxidation-reduction method uses iron filings or ferrous chloride solution as absorbent to absorb Cl in waste gas 2 To obtain the ferric chloride product, but the solution needs to be evaporated and concentrated to recover the ferric chloride product, and the generated steam is easy to cause secondary pollution. The solvent absorption method is to wash the chlorine-containing waste gas in a spray tower by using an organic or inorganic solvent to absorb Cl in the chlorine-containing waste gas 2 The pure chlorine gas is desorbed by heating or pressurizing, and the desorbed solvent is recycled, or the obtained chlorine-containing solvent is used as a raw material in the production process. A commonly used solvent is benzene (C) 6 H 6 ) Sulfur (S) chloride 2 Cl 2 ) Carbon tetrachloride (CC 1) 4 ) Chlorosulfonic acid (HSO) 3 CI) and aqueous iodine disulfide. The solvent absorption process is carried out at a relatively low temperature and a relatively high pressure, and it is carried out with respect to Cl 2 The absorption efficiency of the chlorine dioxide can be close to l 00%, and then the chlorine dioxide is desorbed at higher temperature and lower pressure to obtain high-purity liquid chlorine, and the method has the defects that the solvents are harmful to the environment, the use process needs strict closed circulation, and otherwise, the pollution is easily caused.
SO is contained in sulfur-containing waste gas generated in metallurgy and chemical industry 2 And SO 3 In which SO 3 Water spraying is usually used for absorption. SO (SO) 2 Dissolved in water to form sulfurous acidStable and easy to decompose. Therefore, the methods for purifying sulfur-containing waste gas mainly include a lime milk spraying method and a double alkali method. The lime milk spraying method is simple in process, but easy to scale, mainly generates gas-solid reaction in the spraying process, and is low in desulfurization efficiency which is only 70-80% generally. The double alkali method is to firstly use sodium carbonate solution to absorb SO in the flue gas 2 Then causticizing the absorbed solution by using calcium hydroxide to obtain regenerated sodium carbonate solution, and returning the regenerated sodium carbonate solution to the flue gas desulfurization process for recycling. The desulfurization efficiency of the double alkali method is generally between 90 and 95 percent, but the absorbed liquid can be regenerated only by adding lime for long-time stirring at the temperature close to boiling. The coal-fired flue gas is obtained by a lime milk spraying method, and is black gypsum which is mixed with a large amount of smoke dust and is solid waste which cannot be comprehensively utilized.
In addition to the above methods, it has recently been proposed to use an ammonium salt-containing ammonia solution as a purification solution for chlorine-containing or/and sulfur-containing waste gas, to contact the purification solution with the chlorine-containing or/and sulfur-containing waste gas to absorb chlorine and sulfur therein, to stir the resulting purified solution, to add a calcium-containing alkaline substance such as calcium oxide to adjust the pH, to add sodium sulfate to decalcify the solution, and to return the decalcified solution to the purification step for recycling. The method can purify the waste gas containing chlorine and sulfur to reach the standard and discharge, but the process is complex, the produced industrial gypsum can only be stacked as solid waste, and the industrial gypsum produced all over the country at present is piled up like a mountain and cannot be digested.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the method and the device for purifying the waste gas containing chlorine or/and sulfur and producing the byproduct ammonium salt, which have the advantages of simple process, good purification effect and convenient operation, and can obtain the ammonium salt product while purifying the waste gas containing chlorine or/and sulfur and avoid the generation of solid waste such as gypsum and the like.
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, which comprises the following steps:
the method comprises the following steps: exhaust gas purification
Directly using ammonia-containing gas as a purifying agent for the chlorine-containing or/and sulfur-containing waste gas, or after removing solid impurities included in the chlorine-containing or/and sulfur-containing waste gas through pretreatment, using the ammonia-containing gas as the purifying agent, enabling the purifying agent to be in contact reaction with the chlorine-containing or/and sulfur-containing waste gas to convert chlorine or/and sulfur in the chlorine-containing or/and sulfur-containing waste gas into ammonium salt, adopting circulating spray liquid to capture ammonium salt smoke formed in the purifying process, adjusting the adding amount of the ammonia-containing gas according to the pH value of the circulating spray liquid to ensure that all chlorine or/and sulfur in the waste gas are converted into ammonium salt, and capturing residual ammonia in the purified tail gas by using weak acid solution to reach the standard and discharge;
Step two: by-product ammonium salt
And (3) when the ammonium salt in the circulating spray liquid obtained in the step one is saturated, crystallizing and separating out, carrying out solid-liquid separation, directly returning the obtained crystal to be used as a raw material for preparing ammonia-containing gas, or drying, packaging and selling the crystal as a product, and continuously recycling the residual solution.
The invention relates to a method for purifying a byproduct ammonium salt from chlorine-containing or/and sulfur-containing waste gas, wherein in the step one, the chlorine-containing or/and sulfur-containing waste gas contains HCl or/and Cl 2 Or/and inorganic chlorides of metals and non-metals or/and oxides of sulfur; wherein Cl is more than or equal to 0.01g/m 3 Or/and S is more than or equal to 0.03g/m 3 。
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt.
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, wherein in the first step, the ammonia-containing gas refers to ammonia gas generated by gasifying liquid ammonia; or ammonia-containing gas produced by decomposition of ammonia and an ammonium salt, wherein the decomposition includes thermal decomposition of ammonia and an ammonium salt, or chemical decomposition of an ammonium salt in contact with a basic substance.
The invention relates to a method for purifying a byproduct ammonium salt from chlorine-containing or/and sulfur-containing waste gas, wherein in the first step, the temperature of the contact reaction of a purifying agent and the chlorine-containing or/and sulfur-containing waste gas is 0-100 ℃.
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, which comprises the following steps that in the first step, the adding amount of ammonia-containing gas is adjusted according to the pH value of the circulating spray liquid after ammonium salt smoke is collected, so that the pH value of the circulating spray liquid is controlled to be 6.0-9.5; the circulating spray liquid is preferably water.
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, wherein in the first step, the weak acidic solution is at least one of dilute hydrochloric acid, dilute sulfurous acid and dilute sulfuric acid with the pH value of 3-6.
The invention relates to a method for purifying byproduct ammonium salt from waste gas containing chlorine or/and sulfur, which is characterized in that HCl in purified tail gas treated by weak acidic solution is less than or equal to 0.04mg/m 3 、Cl 2 ≤0.02mg/m 3 、NH 3 ≤0.3mg/m 3 、SO 2 ≤0.05mg/m 3 。
The invention relates to a method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, which has the following basic principle:
TiCl 4 +4NH 3 +2H 2 O＝TiO 2 ↓+4NH 4 Cl (1)
SiCl 4 +4NH 3 +2H 2 O＝SiO 2 ↓+4NH 4 Cl (2)
2AlCl 3 +6NH 3 +3H 2 O＝Al 2 O 3 ↓+6NH 4 Cl (3)
HCl+NH 3 ＝NH 4 Cl (4)
Cl 2 +H 2 O＝HCl+HClO (5)
3HClO+2NH 3 ＝N 2 ↑+3H 2 O+3HCl (6)
SO 2 +2NH 3 +H 2 O＝(NH 4 ) 2 SO 3 (7)
the invention also provides a device for purifying the byproduct ammonium salt from the waste gas containing chlorine or/and sulfur, which comprises a gas-gas reaction spraying purification tower, a 1# liquid-solid separator, a 2# liquid-solid separator, a spraying circulating liquid storage tank, a mixing tank, a gas-liquid separator, a 1# circulating pump and a 2# circulating pump, wherein a weakly acidic solution nozzle, a weakly acidic solution waste gas purification device, a spraying circulating liquid nozzle and a spraying circulating liquid waste gas purification device are sequentially arranged in the gas-gas reaction spraying purification tower from top to bottom, a gas outlet of the gas-gas reaction spraying purification tower is connected with an inlet of the gas-liquid separator, a liquid outlet of the gas-gas reaction spraying purification tower is connected with an inlet of the spraying circulating liquid storage tank, a supernatant outlet of the spraying circulating liquid storage tank is connected with an inlet of the 2# circulating pump, an outlet of the 2# circulating pump is connected with an inlet of the 2# liquid-solid separator, and liquid outlets of the 2# liquid-solid are respectively connected with an inlet of the mixing tank and a spraying circulating liquid of the gas-gas reaction spraying purification tower A spraying circulating liquid nozzle, wherein the outlet of the mixing tank 6 is connected with a weak acid solution nozzle of a gas-gas reaction spraying purification tower; the bottom mud outlet of the spraying circulating liquid storage tank is connected with the inlet of a No. 1 circulating pump, the outlet of the No. 1 circulating pump is connected with the inlet of a No. 1 liquid-solid separator, the liquid outlet of the No. 1 liquid-solid separator is connected with a spraying circulating liquid nozzle of a gas-gas reaction spraying purification tower, and the lower part of the gas-gas reaction spraying purification tower is symmetrically provided with a chlorine or/and sulfur-containing waste gas inlet and an ammonia-containing gas inlet.
The invention relates to a device for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, wherein the weak acid solution waste gas purifying device and the spraying circulating liquid waste gas purifying device are both filler layers capable of promoting gas-liquid exchange, the ratio of the thickness of the filler layers to the inner diameter of a gas-gas reaction spraying purifying tower is 1: 100-2500, and the filler is selected from at least one of a multi-surface hollow sphere, a pall ring, a nylon rope and a plastic net.
The invention relates to a device for purifying byproduct ammonium salt from waste gas containing chlorine or/and sulfur, wherein a plurality of circular sheets and circular sheets are alternately arranged between an inlet (or an inlet containing ammonia gas) of the waste gas containing chlorine or/and sulfur and a spray circulating liquid waste gas purifying device, wherein the outer diameter of each circular sheet is matched with the inner diameter of a cylinder of a gas-gas reaction spray purifying tower, the area of a through hole of each circular sheet is larger than or equal to the sum of the areas of an inlet of the waste gas containing chlorine or/and sulfur and an inlet containing ammonia gas, the diameter of each circular sheet is larger than or equal to the diameter of the through hole of each circular sheet, and the diameter of each circular sheet is smaller than the inner diameter of the cylinder of the gas-gas reaction spray purifying tower.
The invention relates to a device for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt, which is used for detecting and adjusting the temperature, pH and components of a solution in real time in the purification process, wherein pH monitoring devices are respectively arranged at a liquid outlet of a gas-gas reaction spray purification tower, an inlet of a spray circulating liquid nozzle, an inlet of a gas-liquid separator, an inlet of a liquid-solid separator, an outlet and an inlet of a mixing tank;
Regulating valves are arranged at the liquid outlet of the gas-gas reaction spraying purification tower, the liquid outlet of the liquid-solid separator, the outlet of the spraying circulating liquid storage tank and the outlet of the mixing tank, the regulating valves are arranged at the inlet and the outlet of the circulating pump, the one-way valve is arranged at the inlet of the spraying circulating liquid nozzle, thermometers are arranged in the gas-gas reaction spraying purification tower, the spraying circulating liquid storage tank and the mixing tank, and liquid level meters are arranged in the spraying circulating liquid storage tank and the mixing tank.
Compared with the prior art, the invention has the following advantages and effects:
1. the invention uses the gas containing ammonia as the purifying agent of the waste gas containing chlorine or/and sulfur, so that the purifying process of the waste gas containing chlorine or/and sulfur is converted into gas-gas reaction from gas-solid and gas-liquid reaction of the traditional process, and the reaction efficiency of the purifying agent and the chlorine and sulfur in the waste gas is greatly improved.
2. The method purifies the waste gas containing chlorine or/and sulfur by adopting a gas-gas reaction mode, effectively avoids crystallization of ammonium salt in the packing of the spray tower, ensures smooth air passage in the spray tower, collects ammonium salt crystals formed by the gas-gas reaction through spray liquid, converges the ammonium salt crystals at the bottom of the circulating tank, directly separates the liquid from the solid to obtain an ammonium salt product, does not need evaporation crystallization, and greatly reduces the cost of separating and recycling the ammonium salt.
3. The invention firstly uses the gas containing ammonia to contact with the waste gas containing chlorine or/and sulfur, can completely convert the chlorine and sulfur in the waste gas into ammonium salt, and uses the weak acid solution to absorb the residual ammonia in the tail gas, thereby ensuring that the purified gas reaches the standard and is discharged, and the invention has simple process, convenient operation and high purification efficiency.
4. The invention adopts a gas-gas reaction mode to purify the waste gas containing chlorine or/and sulfur, the added purifying agent is gas containing ammonia, the purity of the produced ammonium salt reaches more than 99 percent, the obtained ammonium salt can be sold as a product, and solid wastes such as gypsum and the like are not produced.
Drawings
FIG. 1 is a schematic structural diagram of a purification apparatus for chlorine-containing or/and sulfur-containing waste gas;
the system comprises a gas-liquid separator 1, a gas-gas reaction spray purification tower 2, a spray circulating liquid storage tank 3, a 4-1 # circulating pump, a 4-2 # circulating pump, a 5-1 # liquid-solid separator, a 5-2 # liquid-solid separator, a 6 # mixing tank, a 7 # weakly acidic solution nozzle, a 8 # weakly acidic solution waste gas purification device, a 9 # circulating liquid nozzle, and a 10 # circulating liquid waste gas purification device.
Detailed Description
The invention will now be further described with reference to the following examples, which are intended to illustrate the invention but not to limit it further.
Example 1
A device for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt:
referring to fig. 1, the apparatus for purifying waste gas containing chlorine or/and sulfur to obtain byproduct ammonium salt comprises a gas-liquid separator 1, a gas-gas reaction spray purification tower 2, a spray circulation liquid storage tank 3, a 1# circulation pump 4-1, a 2# circulation pump 4-2, a 1# liquid-solid separator 5-1, a 2# liquid-solid separator 5-2 and a blending tank 6; the gas-liquid separator 1 is a standard gas-liquid separator finished product which is matched with the gas-gas reaction spray purification tower 2 and is made of glass fiber reinforced plastics or carbon steel lined glass fiber reinforced plastics or plastics; the gas-gas reaction spray purification tower 2 is a cylindrical or polygonal tower body made of glass fiber reinforced plastic or carbon steel lined with glass fiber reinforced plastic or plastic, and a weakly acidic solution nozzle 7, a weakly acidic solution waste gas purification device 8, a spray circulating liquid nozzle 9 and a circulating liquid waste gas purification device 10 are sequentially arranged in the gas-gas reaction spray purification tower from top to bottom; the chlorine or/and sulfur-containing waste gas inlet and the ammonia-containing gas inlet are symmetrically and oppositely arranged at a position 50-500 cm away from the bottom of the gas-gas reaction spraying purification tower 2, the weakly acidic solution waste gas purification device and the spraying circulating liquid waste gas purification device can both adopt packing layers capable of promoting gas-liquid exchange, the ratio of the thickness of the packing layers to the inner diameter of the gas-gas reaction spraying purification tower is 1: 100-2500, and the packing is selected from at least one of a multi-surface hollow sphere, a pall ring, a nylon rope and a plastic net.
The gas-gas reaction section is a reaction section between an inlet (or an inlet containing ammonia gas) of waste gas containing chlorine or/and sulfur and a circulating liquid waste gas purification device 10, the length-diameter ratio of the reaction section is 1-20: 1, in order to promote the mixing of gas and gas, a plurality of circular sheets and circular sheets are alternately arranged in the gas-gas reaction section for partition, wherein the outer diameter of each circular sheet is matched with the inner diameter of the gas-gas reaction spray purification tower cylinder, the area of a through hole of each circular sheet is larger than or equal to the sum of the areas of the inlet containing chlorine or/and sulfur waste gas and the inlet containing ammonia gas, the diameter of each circular sheet is larger than or equal to the diameter of the through hole of each circular ring, and the diameter of each circular sheet is smaller than the inner diameter of the gas-gas reaction spray purification tower cylinder; the weakly acidic solution nozzle 7 is arranged in the center of the top end of the gas-gas reaction spraying purification tower 2, the opening of the nozzle is downward, the distance between the outlet of the nozzle and the upper part of the weakly acidic solution waste gas purification device is 10-100 cm, and ammonia remained in the purified tail gas is neutralized and absorbed by the weakly acidic solution; the spraying circulating liquid nozzle 9 is arranged at the lower part of the weakly acidic solution waste gas purification device, the opening of the nozzle is downward, the outlet of the nozzle is 30-150 cm away from the upper part of the circulating liquid waste gas purification device, one-way valves are respectively arranged on two liquid inlet pipes of the spraying circulating liquid nozzle 9, the spraying circulating liquid can only be sprayed out from the spraying circulating liquid nozzle 9, and the sprayed circulating solution catches ammonium salt smoke formed in the gas-gas reaction spraying purification tower 2;
A gas outlet of the gas-gas reaction spraying purification tower 2 is connected with an inlet of the gas-liquid separator 1, a liquid outlet of the gas-gas reaction spraying purification tower 2 is connected with an inlet of a spraying circulating liquid storage tank 3, a supernatant outlet of the spraying circulating liquid storage tank 3 is connected with an inlet of a 2# circulating pump 4-2, an outlet of the 2# circulating pump 4-2 is connected with an inlet of a 2# liquid-solid separator 5-2, and suspended matters in the suspended matters are separated; the liquid outlet of the 2# liquid-solid separator 5-2 is respectively connected with the inlet of the mixing tank 6 and the spray circulating liquid nozzle 9 of the gas-gas reaction spray purification tower 2, and the outlet of the mixing tank 6 is connected with the weak acid solution nozzle 7 of the gas-gas reaction spray purification tower 2; a bottom mud outlet of the spraying circulating liquid storage tank 3 is connected with an inlet of a 1# circulating pump 4-1, an outlet of the 1# circulating pump 4-1 is connected with an inlet of a 1# liquid-solid separator 5-1, and ammonium salt crystals separated by crystallization are separated; the liquid outlet of the No. 1 liquid-solid separator 5-1 is connected with a spray circulating liquid nozzle 9 of the gas-gas reaction spray purification tower 2.
For convenience of operation, the temperature, pH and components of the solution are detected and adjusted in real time in the purification process, and pH monitoring devices are arranged at a liquid outlet of the gas-gas reaction spray purification tower 2, an inlet of the spray circulating liquid nozzle 9, an inlet of the gas-liquid separator 1, an inlet of the No. 1 liquid-solid separator, an inlet of the No. 2 liquid-solid separator, an outlet and an inlet of the mixing tank;
Regulating valves are arranged at a liquid outlet of the gas-gas reaction spraying purification tower 2, a liquid outlet of the No. 1 liquid-solid separator, a liquid outlet of the No. 2 liquid-solid separator, an outlet of the spraying circulating liquid storage tank 3 and an outlet of the mixing tank 6, regulating valves are arranged at an inlet and an outlet of the No. 1 circulating pump and an inlet and an outlet of the No. 2 circulating pump, a one-way valve is arranged at an inlet of a spraying circulating liquid nozzle 9, thermometers are arranged in the gas-gas reaction spraying purification tower 2, the spraying circulating liquid storage tank 3 and the mixing tank 6, and liquid level meters are arranged in the spraying circulating liquid storage tank 3 and the mixing tank 6.
The specific process is as follows:
introducing chlorine or/and sulfur-containing waste gas and ammonia-containing gas into a gas-gas reaction spray purification tower at the same time, converting chlorine or/and sulfur in the chlorine or/and sulfur-containing waste gas into ammonium salt after contact reaction, trapping ammonium salt smoke formed in the purification process by using spray circulating liquid sprayed by a spray circulating liquid nozzle, adjusting the addition amount of the ammonia-containing gas according to the pH value of the circulating spray liquid, ensuring that all chlorine or/and sulfur in the waste gas are converted into ammonium salt, and trapping residual ammonia in the tail gas by using weak acid solution sprayed by a weak acid solution nozzle to reach the standard and discharge; the solution sprayed from the spray circulating liquid nozzle and the weak acid solution nozzle is converged into a spray circulating liquid storage tank, ammonium salt crystals are separated out and converged at the bottom of the spray circulating liquid storage tank, the ammonium salt crystals enter a No. 1 liquid-solid separator through a No. 1 circulating pump, the ammonium salt crystals separated out by crystallization are separated, and the residual liquid in the No. 1 liquid-solid separator is used as circulating spray liquid and is sent to the spray circulating liquid nozzle for recycling; supernatant in the spraying circulating liquid storage tank enters a 2# liquid-solid separator through a 2# circulating pump to separate suspended matters in the supernatant, and the residual liquid part in the 2# liquid-solid separator is sent to a mixing tank, is subjected to pH adjustment by dilute acid and then is sprayed out from a weak acid solution nozzle to capture and purify residual ammonia in tail gas; and part of the circulating spray liquid is sent to the spray circulating liquid nozzle to be used as the circulating spray liquid for recycling, so that the closed circulation of the circulating spray liquid in the device is realized.
Example 2
Tail gas of boiling chlorination furnace (containing titanium tetrachloride) for producing titanium tetrachlorideHCl、Cl 2 、TiCl 4 、SiCl 4 、CO、CO 2 Etc.) purifying in the device shown in figure 1, using ammonia-containing gas generated by thermal decomposition of ammonium bicarbonate as a purifying agent of chlorine-containing waste gas, mixing and purifying the chlorine-containing waste gas and the purifying agent, completely converting chlorine in the chlorine-containing waste gas into ammonium chloride, circularly spraying and collecting ammonium chloride smoke formed in the purification process by using water, collecting ammonia remained in dechlorination tail gas by using circulating liquid with pH of 3.5-5.5 after being acidified by dilute hydrochloric acid, discharging the ammonia after reaching the standard, collecting solution flowing out of a gas-gas reaction spraying and purifying tower into a spraying circulating liquid storage tank, settling and separating ammonium chloride in the circulating liquid storage tank, removing hydrolysis precipitate in the obtained supernatant through liquid-solid separation, returning the filtrate for recycling, obtaining ammonium chloride crystals through liquid-solid separation of obtained bottom mud, and returning the obtained filtrate for recycling; in the operation process, the adding amount of ammonia-containing gas is adjusted according to the change of the pH value of the circulating spray liquid, so that the pH value of the effluent liquid at the liquid outlet of the gas-gas reaction spray purification tower is controlled to be 6.5-8.5; the obtained purified tail gas treated by the dilute hydrochloric acid contains NH 3 0.1mg/m 3 、HCl 0.01mg/m 3 、Cl 2 0.005mg/m 3 And the grade of the ammonium chloride produced in the purification process reaches 99.1 percent after the ammonium chloride is dried.
Example 3
Containing SO 2 Purifying 0.02% of tail gas from acid production in the device shown in FIG. 1, using ammonia gas as purifying agent, mixing the tail gas from acid production with the purifying agent, and purifying to obtain SO 2 All the ammonia is converted into ammonium sulfite, ammonium sulfite smoke formed in the purification process is collected by water circulating spraying, and residual ammonia in the desulfurization tail gas is collected by circulating liquid which is acidified by dilute sulfurous acid and has the pH value of 3-5 and then is discharged after reaching the standard; collecting the solution flowing out of the gas-gas reaction spray purification tower to a spray circulating liquid storage tank, settling and separating ammonium sulfite in the spray circulating liquid storage tank, returning the filtrate for recycling after liquid-solid separation of the obtained supernatant, and returning the obtained bottom mud for recycling after liquid-solid separation to obtain ammonium sulfite crystals, wherein the obtained filtrate is also returned for recycling; in the operation process, the adding amount of ammonia gas is adjusted according to the change of the pH value of the circulating spray liquid, and the pH value of the effluent liquid at the liquid outlet of the gas-gas reaction spray purification tower is controlled to be 7.0-9.0; the obtained purified tail gas treated by dilute sulfurous acid contains NH 3 0.15mg/m 3 、SO 2 0.03mg/m 3 Removal rate of sulfur>99.5 percent, and the grade of the ammonium sulfite produced in the purification process reaches 99.8 percent after being dried.
Example 4
Containing HCl 0.26%, Cl 2 0.03％、SO 2 Purifying 0.01% of sodium-modified roasted flue gas of stone coal in a device shown in figure 1, using ammonia-containing gas generated by the reaction of lime milk and ammonium sulfate as a purifying agent, mixing and purifying the flue gas and the purifying agent, completely converting chlorine in the flue gas into ammonium chloride, converting sulfur into ammonium sulfite, circularly spraying and collecting ammonium chloride and ammonium sulfite smoke formed in the purification process by using water, collecting residual ammonia in purified tail gas by using circulating liquid with the pH value of 3-6 after being acidified by dilute hydrochloric acid, discharging the ammonia after reaching the standard, collecting solution flowing out of a gas-gas reaction spraying and purifying tower into a spraying circulating liquid storage tank, settling and separating ammonium chloride in the tank, removing suspended matters in supernatant through liquid-solid separation, returning the obtained filtrate for recycling, separating crystallized ammonium chloride crystals in bottom mud through liquid-solid separation, returning the obtained filtrate for recycling, and enriching the concentration of ammonium sulfite in ammonium chloride crystallization mother liquor to 650g/L, the extracted part reacts with lime milk to produce ammonia-containing gas required by flue gas purification, the obtained ammonium chloride crystal is washed by saturated ammonium chloride solution and then dried, the grade reaches 99.3%, and the obtained purified tail gas treated by dilute hydrochloric acid contains NH30.11mg/m3, HCl 0.006mg/m3 and Cl 2 0.003 mg/m3、SO 2 0.02mg/m3, and the removal rate of chlorine and sulfur in the purification process>99％。
Claims (7)
1. A method for purifying waste gas containing chlorine or/and sulfur to obtain a byproduct ammonium salt is characterized by comprising the following steps:
the method comprises the following steps: exhaust gas purification
Directly using ammonia-containing gas as a purifying agent for the chlorine-containing or/and sulfur-containing waste gas, or after removing solid impurities included in the chlorine-containing or/and sulfur-containing waste gas through pretreatment, using the ammonia-containing gas as the purifying agent, enabling the purifying agent to be in contact reaction with the chlorine-containing or/and sulfur-containing waste gas to convert chlorine or/and sulfur in the chlorine-containing or/and sulfur-containing waste gas into ammonium salt, adopting circulating spray liquid to capture ammonium salt smoke formed in the purifying process, adjusting the adding amount of the ammonia-containing gas according to the pH value of the circulating spray liquid to ensure that all chlorine or/and sulfur in the waste gas are converted into ammonium salt, and capturing residual ammonia in the purified tail gas by using weak acid solution to reach the standard and discharge;
step two: by-product ammonium salt
When the ammonium salt in the circulating spray liquid obtained in the step one is saturated, crystallizing and separating out, carrying out solid-liquid separation, directly returning the obtained crystals to be used as a raw material for preparing ammonia-containing gas, or drying and packaging the crystals to be used as a product for sale, and continuously recycling the residual solution;
in the first step, the ammonia-containing gas is ammonia gas generated by gasifying liquid ammonia; or ammonia-containing gas generated by decomposing ammonia water and ammonium salt, wherein the decomposition comprises thermal decomposition of the ammonia water and the ammonium salt, or chemical decomposition of the ammonium salt in contact with a basic substance;
The device matched with the method for purifying the byproduct ammonium salt from the waste gas containing chlorine or/and sulfur comprises a gas-gas reaction spraying purification tower (2), a No. 1 liquid-solid separator (5-1), a No. 2 liquid-solid separator (5-2), a spraying circulating liquid storage tank (3), a mixing tank (6), a gas-liquid separator (1), a No. 1 circulating pump (4-1) and a No. 2 circulating pump (4-2), wherein a weakly acidic solution nozzle (7), a weakly acidic solution waste gas purification device (8), a spraying circulating liquid nozzle (9) and a spraying circulating liquid waste gas purification device (10) are sequentially arranged in the gas-gas reaction spraying purification tower (2) from top to bottom, a gas outlet of the gas-gas reaction spraying purification tower (2) is connected with an inlet of the gas-liquid separator (1), a liquid outlet of the gas-gas reaction spraying purification tower (2) is connected with an inlet of a spraying circulating liquid storage tank (3), a supernatant outlet of the spraying circulating liquid storage tank (3) is connected with an inlet of a 2# circulating pump (4-2), an outlet of the 2# circulating pump (4-2) is connected with an inlet of a 2# liquid-solid separator (5-2), a liquid outlet of the 2# liquid-solid separator (5-2) is respectively connected with an inlet of a mixing tank (6) and a spraying circulating liquid nozzle (9) of a gas-gas reaction spraying purification tower (2), an outlet of the mixing tank (6) is connected with a weakly acidic solution nozzle (7) of the gas-gas reaction spraying purification tower (2), a bottom mud outlet of the spraying circulating liquid storage tank (3) is connected with an inlet of a 1# circulating pump (4-1), an outlet of the 1# circulating pump (4-1) is connected with an inlet of a 1# liquid-solid separator (5-1), a liquid outlet of the 1# liquid-solid separator (5-1) is connected with the spraying circulating liquid nozzle (9) of the gas-gas reaction spraying purification tower (2), the lower part of the gas-gas reaction spray purification tower 2 is symmetrically provided with a chlorine or/and sulfur-containing waste gas inlet and an ammonia-containing gas inlet;
A plurality of circular ring sheets and circular sheets are alternately arranged between the inlet of the chlorine-containing or/and sulfur-containing waste gas and the spraying circulating liquid waste gas purification device (10), wherein the outer diameter of each circular ring sheet is matched with the inner diameter of the cylinder of the gas-gas reaction spraying purification tower (2), the area of a through hole of each circular ring sheet is larger than or equal to the sum of the areas of the chlorine-containing or/and sulfur-containing waste gas inlet and the ammonia-containing gas inlet, the diameter of each circular sheet is larger than or equal to the diameter of the through hole of each circular ring sheet, and the diameter of each circular sheet is smaller than the inner diameter of the cylinder of the gas-gas reaction spraying purification tower (2).
2. The method according to claim 1, wherein the ammonium salt is produced by purifying the waste gas containing chlorine and/or sulfur by-production of the ammonium salt, and the method comprises the steps of: in the first step, the chlorine-containing or/and sulfur-containing waste gas contains HCl or/and Cl 2 Or/and metal chlorides or/and inorganic chlorides of non-metals or/and oxides of sulphur.
3. The method according to claim 1, wherein the ammonium salt is produced by purifying the waste gas containing chlorine and/or sulfur by-production of the ammonium salt, and the method comprises the steps of: in the first step, the pretreatment is to separate solid impurities from the chlorine-containing or/and sulfur-containing waste gas by dry filtration, or to remove solid impurities from the chlorine-containing or/and sulfur-containing waste gas by spray washing or dynamic wave washing.
4. The method according to claim 1, wherein the ammonium salt is produced by purifying the waste gas containing chlorine and/or sulfur by-production of the ammonium salt, and the method comprises the steps of: in the first step, the temperature of the contact reaction of the purifying agent and the chlorine-containing or/and sulfur-containing waste gas is 0-100 ℃.
5. The method according to claim 1, wherein the ammonium salt is produced by purifying the waste gas containing chlorine and/or sulfur by-production of the ammonium salt, and the method comprises the steps of: in the first step, the adjustment of the adding amount of the ammonia-containing gas refers to adjusting the adding amount of the ammonia-containing gas according to the pH value of the circulating spray liquid after ammonium salt smoke is collected, so that the pH value of the circulating spray liquid is controlled to be 6.0-9.5.
6. The method according to claim 1, wherein the ammonium salt is produced by purifying the waste gas containing chlorine and/or sulfur by-production of the ammonium salt, and the method comprises the steps of: in the first step, the weak acidic solution is at least one of dilute hydrochloric acid, dilute sulfurous acid and dilute sulfuric acid with the pH of 3-6.
7. The method for purifying a byproduct ammonium salt of chlorine-containing or/and sulfur-containing exhaust gas according to any one of claims 1 to 6, wherein: HCl in the purified tail gas treated by weak acidic solution is less than or equal to 0.04mg/m 3 、Cl 2 ≤0.02mg/ m 3 、NH 3 ≤0.3mg/ m 3 、SO 2 ≤0.05mg/m 3 。
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| US7255842B1 (en) * | 2003-09-22 | 2007-08-14 | United States Of America Department Of Energy | Multi-component removal in flue gas by aqua ammonia |
| CN201609632U (en) * | 2009-12-30 | 2010-10-20 | 湖北郧西隆昌钒业有限公司 | Compound purifying tower |
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