CN111841237A - Method for inhibiting SRG flue gas crystallization - Google Patents
Method for inhibiting SRG flue gas crystallization Download PDFInfo
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- CN111841237A CN111841237A CN201910355203.5A CN201910355203A CN111841237A CN 111841237 A CN111841237 A CN 111841237A CN 201910355203 A CN201910355203 A CN 201910355203A CN 111841237 A CN111841237 A CN 111841237A
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- B01D53/02—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 adsorption, e.g. preparative gas chromatography
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Abstract
A method of inhibiting SRG flue gas crystallization, the method comprising the steps of: 1) and adsorbing nitrogen dioxide by using the activated carbon in advance to obtain the activated carbon I. 2) The activated carbon adsorbing the pollutants is marked as activated carbon II, and the activated carbon II is mixed with the activated carbon I obtained in the step 1). 3) And (3) carrying out a regeneration process on the mixture of the activated carbon II and the activated carbon I obtained in the step 2) to obtain SRG gas. Compared with the prior art, the method for inhibiting the SRG flue gas crystallization provided by the invention can prevent the pipeline from being blocked and reduce the loss of sulfur resources.
Description
Technical Field
The invention relates to a method for inhibiting flue gas crystallization, in particular to a method for inhibiting SRG flue gas crystallization, and belongs to the technical field of flue gas purification.
Background
The flue gas pollution emission control technology of the activated carbon utilizes the characteristic that the activated carbon has rich functional groups and larger specific surface area, and the activated carbon can simultaneously remove SO in compressed air2、NOxDust, VOCs, heavy metals, halogens and other pollutants, and the activated carbon with saturated adsorption can pass through the activated carbonCan be recycled after the birth and has wide development prospect. The active carbon smoke control technology has been developed for more than fifty years so far, and a series of processes are developed at home and abroad successively, and representative processes comprise a Reinluft process, a Sumitomo process and a Westvaco process.
During the regeneration of the activated carbon, a sulfur-rich gas (SRG gas) having a high concentration is generated. The early detection result shows that the sulfur-rich gas contains pollutants such as ammonia gas, hydrogen chloride, dust and the like besides high-concentration sulfur dioxide. However, the SRG gas generated by the activated carbon process is easy to cause ammonium chloride crystallization blockage, and the reason for the blockage is mainly that the concentration of ammonia gas and hydrogen chloride gas in the SRG gas is high. In the production process, nitrogen oxides exist in multi-pollutant flue gas, a certain amount of ammonia needs to be added, and in order to ensure denitration efficiency, the adding amount of ammonia is 1-1.3 times of a theoretical value. The ammonia gas is easily absorbed by the active carbon, and the excessive ammonia gas is absorbed by the active carbon to form AC-NH3The substance of (1); meanwhile, the flue gas contains a large amount of hydrogen chloride, so that the flue gas is easily adsorbed by activated carbon to form an AC-HCl substance. In addition, because the ammonia is added excessively and the reaction of the ammonia and the nitrogen oxide is not complete, the AC-NH is increased3And (4) forming a substance.
AC-NH3The substance (A) and the substance (C-HCl) can be desorbed by means of an activated carbon heating regeneration method to form NH3HCl and Activated Carbon (AC). The ammonia gas is easy to generate gas-phase crystallization reaction with the hydrogen chloride under the conditions of low temperature and high concentration, so that ammonium chloride crystals are formed. Large-area crystallization of the SRG pipeline can be caused, so that blockage and corrosion are caused, and the active carbon flue gas purification system is seriously influenced.
In the actual production process, ammonia gas is added in excess, AC-NH3The substance is resolved by the heating regeneration method of the active carbon to form NH3。NH3The sulfur-containing SRG gas enters the SRG gas, so that the ammonia content in the SRG gas is high, and meanwhile, because the concentration of sulfur oxides in the SRG gas is high, the crystallization of ammonium sulfate is easily formed, so that sulfur resources are consumed while the SRG gas conveying pipeline is blocked and corroded, and the efficiency of recycling the sulfur resources is reduced.
The prevention of the formation of ammonium chloride crystals and ammonium sulfate crystals is a precondition for ensuring the normal operation of the activated carbon flue gas purification system. The method for preventing ammonium chloride crystallization and ammonium sulfate crystallization commonly used in the industry at present mainly comprises heating or heat preservation treatment of SRG flue gas, but the method has the defects of high investment cost and unstable operation.
Therefore, how to provide a method for inhibiting the crystallization of SRG flue gas can ensure that the SRG flue gas is not easy to crystallize when passing through an SRG pipeline, prevent the pipeline from being blocked and corroded, and ensure the stability of the production rate. Has become a technical problem to be solved by those skilled in the art.
Disclosure of Invention
Aiming at the problem that the SRG gas conveying pipeline is easy to block and corrode in the prior art, the invention aims to provide a method for inhibiting SRG flue gas crystallization. Specifically, active carbon I which adsorbs nitrogen dioxide in advance is mixed with active carbon II which adsorbs pollutants; the nitrogen dioxide can react with ammonia gas in pollutants in the regeneration process of the activated carbon to generate nitrogen gas and water, so that the content of the ammonia gas in the SRG gas is reduced; preventing ammonia gas in the SRG gas from reacting with hydrogen halide and sulfide in the SRG gas conveying process to generate crystals; the purposes of preventing pipeline blockage, avoiding the corrosion of SRG gas conveying pipelines and reducing sulfide loss are achieved.
According to an embodiment of the invention, there is provided a method of inhibiting SRG flue gas crystallization:
a method of inhibiting SRG flue gas crystallization, the method comprising the steps of:
1) and adsorbing nitrogen dioxide by using the activated carbon in advance to obtain the activated carbon I.
2) The activated carbon adsorbing the pollutants is marked as activated carbon II, and the activated carbon II is mixed with the activated carbon I obtained in the step 1).
3) And (3) carrying out a regeneration process on the mixture of the activated carbon II and the activated carbon I obtained in the step 2) to obtain SRG gas.
Preferably, the method further comprises: and 4) carrying out sulfur resource recovery on the SRG gas obtained in the step 3).
Preferably, after the regeneration process, the activated carbon II and the activated carbon I become fresh activated carbon, and are recycled to: step 1) for adsorbing nitrogen dioxide and/or step 2) for adsorbing contaminants.
Preferably, the amount of nitrogen dioxide adsorbed by the activated carbon in the activated carbon I in the step 1) is 30-100%, preferably 40-99%, more preferably 50-98%, and even more preferably 60-97% of the saturated adsorption amount of nitrogen dioxide by the activated carbon.
Preferably, the process conditions of the activated carbon pre-adsorbing nitrogen dioxide in the step 1) are as follows: normal temperature or higher than normal temperature and/or normal pressure or higher than normal pressure.
Preferably, the contaminants in step 2) originate from flue gases, preferably from sintering flue gases.
Preferably, the flue gas contains NOx and SO2One or more of dust, VOCs, heavy metals and halogen.
Preferably, the flue gas is flue gas containing nitrogen oxides and is derived from one or more of steel, electric power, nonferrous metal, petrochemical, chemical industry and building material industry.
Preferably, the temperature of the flue gas is 80-250 ℃, preferably 100-200 ℃, further preferably 120-180 ℃, and more preferably 130-160 ℃.
Preferably, the activated carbon II in the step 2) is activated carbon adsorbing pollutants, and ammonia gas is sprayed in the process of adsorbing the pollutants.
Preferably, the molar weight of the injected ammonia gas in unit time is 0.8-2 times of the molar weight of NOx contained in the pollutants in unit time; preferably 0.9 to 1.8 times; more preferably 1.0 to 1.5 times.
Preferably, the weight ratio of the activated carbon II in the step 2) to the activated carbon I obtained in the step 1) is 0.05 to 2 times, preferably 1:0.05 to 2, preferably 1:0.1 to 1.5, more preferably 1:0.2 to 1, and even more preferably 1:0.3 to 0.5.
Preferably, the regeneration in the step 3) is thermal regeneration, and the regeneration process is to heat the mixture of the activated carbon II and the activated carbon I.
Preferably, the heating is electric heating or hot air heating.
Preferably, the temperature of the regeneration process in step 3) is from 200 ℃ to 600 ℃, preferably from 250 ℃ to 520 ℃, preferably from 300 ℃ to 480 ℃, and more preferably from 350 ℃ to 450 ℃.
Preferably, the sulfur resource recovery of the SRG gas in the step 4) is a sulfuric acid production treatment of the SRG gas.
Preferably, the SRG gas contains no or very little NH3。
In the present invention, the SRG gas contains a very small amount of NH3Meaning that the ammonia content is less than 50 ppm.
In the invention, the active carbon I which adsorbs nitrogen dioxide in advance is mixed with the active carbon which adsorbs pollutants; the carbon dioxide may react with the contaminants on-time to form ammonia and water. Thereby preventing the ammonia gas from reacting with the halogen and the sulfide in the pollutant to generate crystals. The aims of preventing pipeline blockage and reducing sulfide loss are fulfilled. Thus, the SRG gas obtained in step 3) is characterized by a high sulphur content compared to the prior art. Meanwhile, because the generation of crystals is inhibited, the SRG gas discharge pipeline can keep stable gas output, and the processing link can be monitored.
It should be noted that the reaction chemical formula of nitrogen dioxide and nitrogen gas is: 8NH 3+6NO2→7N2+12H2O。
It is further stated that NO is released as a result of activated carbon I2And NH3React to form N2Therefore, the SRG gas is mainly HCl, and the flue gas crystallization cannot be caused. However, in the prior art, since SRG gas mainly contains NH3And HCl, reacting to produce NH4And crystallizing the Cl. NH (NH)3The reaction with HCl is of the formula:
NH produced by the reaction4The Cl crystals will adhere to the vent pipe and be corrosive to the equipment. Increasing rabbetAnd industrial maintenance costs.
It needs to be further explained; in step 2) of the scheme of the invention, activated carbon I and activated carbon II are preferably mixed. When the activated carbon regeneration process is carried out, the nitrogen dioxide of the activated carbon I is in full contact with the ammonia gas in the activated carbon II, and the nitrogen dioxide and the ammonia gas are ensured to be completely reacted to generate nitrogen and water. And preventing part of ammonia gas from directly entering the vent pipe without reacting with nitrogen dioxide.
It is further noted that; ammonium chloride belongs to a substance which is easily decomposed by heating, and the chemical formula of the decomposition of the ammonium chloride is as follows: NH (NH)4Cl→NH3↓directionand × + HCl ×). When the mixture of the activated carbon I and the activated carbon II is subjected to a regeneration process, ammonium chloride cannot be generated even if ammonia gas contacts hydrochloric acid gas in a high-temperature environment. Meanwhile, due to the high-temperature environment of the activated carbon regeneration process, the nitrogen dioxide and the ammonia gas can be subjected to a centering reaction better, so that the reaction of the nitrogen dioxide and the ammonia gas is more sufficient.
Therefore, compared with the prior art, the scheme of the invention mixes the activated carbon I adsorbing the nitrogen dioxide and the activated carbon II adsorbing the pollutants, and then carries out the activated carbon regeneration process. Firstly, using a chemical principle as a basis, converting nitrogen dioxide and ammonia gas into nitrogen gas, and preventing the generation of ammonium chloride; secondly, by using a physical principle as an auxiliary, the nitrogen dioxide of the activated carbon I is fully contacted with the ammonia gas in the activated carbon II by mixing the activated carbon I and the activated carbon II, so that the ammonia gas removal efficiency is improved; thirdly, the high-temperature environment of the activated carbon regeneration process is utilized to ensure that the reaction of the nitrogen dioxide and the ammonia gas is smoothly carried out; fourthly, the SRG gas generated by the process has single impurity, and only a small amount of nitrogen dioxide except sulfide is available, so that the difficulty of later purification is reduced. In conclusion, the scheme of the invention can efficiently remove ammonia in the SRG gas. The method has the advantages of inhibiting the generation of ammonium chloride and ammonium sulfate, and having great significance for reducing the loss of sulfides, improving the production efficiency and protecting equipment safety and stability.
Meanwhile, the scheme of the invention has the characteristics of simple operation, high controllability, low production cost, no secondary pollution and the like. The existing activated carbon flue gas purification system is little modified, and the modification cost is low. After the method is used, the temperature of the SRG flue gas can be reduced, the scale of the SRG subsequent washing, cooling and purifying equipment is further reduced, and the investment cost is greatly reduced.
In the present invention, the generated SRG gas is subjected to recovery of sulfur resources. The SRG gas can generate economical products such as sulfuric acid and the like through an acid making process. The industrial added value is improved.
It should be noted that, in steps 2) and 3) of the scheme, the nitrogen and the nitrogen dioxide are subjected to a centering reaction; therefore, ammonia gas and sulfide do not generate ammonium sulfate or ammonium bisulfate crystals under high temperature conditions. Resulting in high sulfur content in the SRG gas. Reducing the passage of sulfur resources.
It should be further noted that ammonium bisulfate and ammonium sulfate are easily decomposed by heat.
In the invention, after the regeneration process, the activated carbon II and the activated carbon I are changed into fresh activated carbon, and the fresh activated carbon is recycled to the step 1) and/or the step 2) for adsorbing nitrogen dioxide and/or pollutants. The utilization rate of the active carbon is improved, and the production cost is saved.
In the invention, the amount of nitrogen dioxide adsorbed in the activated carbon I can be adsorbed according to actual requirements. If the amount of pollutants adsorbed by the activated carbon in the earlier unit weight is large, the amount of nitrogen dioxide adsorbed in the activated carbon I is increased; if the amount of contaminants adsorbed by the earlier unit weight of activated carbon is small, the amount of nitrogen dioxide adsorbed in activated carbon i is reduced. The amount of the nitrogen dioxide adsorbed in the activated carbon I can be adjusted within the range of 30-100% of the saturated adsorption amount of the activated carbon to the nitrogen dioxide.
The larger the amount of nitrogen dioxide adsorbed in the activated carbon i is, the longer the whole process time of the activated carbon i for adsorbing nitrogen dioxide is; the smaller the amount of nitrogen dioxide adsorbed in the activated carbon I is, the shorter the whole process time of the activated carbon I for adsorbing the nitrogen dioxide is; therefore, the amount of the nitrogen dioxide adsorbed in the activated carbon I is flexibly adjusted, so that the production resource is saved and the production efficiency is improved.
In the application, the process conditions of pre-adsorbing nitrogen dioxide by the activated carbon in the step 1) are as follows: normal temperature or higher than normal temperature and/or normal pressure or higher than normal pressure. According to the requirements of the whole process on the amount of the activated carbon I and the nitrogen dioxide content of the activated carbon I in the process. The aim of adjusting the speed and the adsorption quantity of the activated carbon for adsorbing the nitrogen dioxide is achieved by adjusting the process conditions, such as temperature and/or air pressure, of the activated carbon for adsorbing the nitrogen dioxide in advance. Thereby being beneficial to the control of the whole production process.
It should be noted that, the higher the temperature, the faster the relative movement of the gas molecules, and the less easily the gas molecules are bound, i.e. the lower the adsorption rate of the activated carbon; the lower the temperature, the slower the relative motion of the gas molecules, and the easier it is to bind, i.e. the higher the adsorption rate of the activated carbon. The higher the gas pressure is, the higher the density of gas molecules is, the higher the probability of collision with the activated carbon in unit time is, and the more easily the gas molecules are adsorbed by the activated carbon; the lower the gas pressure, the lower the density of the gas molecules, the less likely it is to collide with the activated carbon per unit time, and the less likely it is to be adsorbed by the activated carbon. Therefore, the adsorption efficiency and the adsorption quantity of the activated carbon to the nitrogen dioxide gas can be effectively controlled by adjusting the gas temperature and the gas pressure.
In the present invention, the contaminants in step 2) originate from flue gases, preferably from sintering flue gases. The invention scheme provided by the invention is suitable for treating the activated carbon which adsorbs the pollutants into the smoke. Is more suitable for treating the activated carbon adsorbing the sintering flue gas. But does not exclude process schemes where the source of the contaminants is other gases or liquids.
In the present invention, the flue gas contains NOx and SO2One or more of dust, VOCs, heavy metals and halogen. The scheme of the invention is more effectively used for treating the activated carbon adsorbing the mixed flue gas. Effectively reacting ammonia gas with nitrogen dioxide, namely effectively preventing ammonium chloride crystals or ammonium sulfate crystals from being generated. The service life of the equipment is prolonged.
In the invention, the flue gas is flue gas containing nitrogen oxides generated in one or more of steel, electric power, nonferrous metal, petrochemical industry, chemical industry and building material industry. The method is more effective in treating the activated carbon of the flue gas adsorbed with the nitrogen oxides. Effectively reacting ammonia gas with nitrogen dioxide, namely effectively preventing ammonium chloride crystals or ammonium sulfate crystals from being generated. The service life of the equipment is prolonged.
In the invention, the temperature of the activated carbon II for adsorbing the flue gas is 80-250 ℃, preferably 100-200 ℃, further preferably 120-180 ℃, and more preferably 130-160 ℃. The adsorption of the active carbon II on the impurities in the flue gas and the purification of the flue gas by the active carbon II are facilitated. In the process, the adsorption speed of the activated carbon II on the impurity gas in the flue gas is adjusted. The process temperature of the activated carbon during flue gas adsorption is adjustable.
In the invention, the activated carbon II in the step 2) is activated carbon adsorbing pollutants, and ammonia gas is sprayed in the process of adsorbing the pollutants. The method is favorable for removing nitrogen oxides in the pollutant flue gas; the nitrogen oxides react with ammonia gas to form nitrogen and water.
Among nitrogen oxides, nitrogen oxides other than nitrogen dioxide are extremely unstable. It is very easily changed into nitrogen dioxide when exposed to light, moisture or heat. All nitrogen dioxide has varying degrees of toxicity. The physicochemical properties of different nitrogen oxides are different, and the nitrogen oxides are non-combustible substances and can support combustion, such as nitrous oxide (N)2O), nitrogen dioxide and dinitrogen pentoxide can cause explosions when exposed to high temperatures or flammable substances. And therefore should be removed as early as possible. Therefore, in the step 2), ammonia gas is added when the active carbon II adsorbs the pollutants, so that the ammonia gas reacts with the nitrogen oxides.
In the invention, in order to ensure that the nitrogen oxides in the flue gas in the step 2) can be fully and completely reacted with ammonia gas, the molar quantity of the injected ammonia gas in unit time can be adjusted according to the molar quantity of NOx contained in pollutants in the unit time; the molar weight of the ammonia gas sprayed in unit time is 0.8-2 times of the molar weight of NOx contained in the pollutants in unit time; preferably 0.9 to 1.8 times; more preferably 1.0 to 1.5 times.
In the invention, the adopted activated carbon regeneration process is a heating regeneration method. The heat regeneration method is the most applied and industrially most mature activated carbon regeneration method. The thermal regeneration method has the characteristics of high regeneration efficiency and wide application range. There are various methods for regenerating activated carbon, for example: thermal regeneration, biological regeneration, wet oxidation, solvent regeneration, electrochemical regeneration, catalytic wet oxidation, and the like. Among them, the thermal regeneration method is most advantageous for the scheme of the invention.
Ammonium chloride belongs to a substance which is easily decomposed by heat, and the chemical formula of the decomposition of ammonium chloride is as follows:
when the mixture of the activated carbon I and the activated carbon II is subjected to a regeneration process, ammonium chloride cannot be generated even if ammonia gas contacts hydrochloric acid gas in a high-temperature environment. Meanwhile, due to the high-temperature environment of the activated carbon regeneration process, the nitrogen dioxide and the ammonia gas can be subjected to a centering reaction better, so that the reaction of the nitrogen dioxide and the ammonia gas is more sufficient. Therefore, the invention adopts the heating regeneration method of the activated carbon. The nitrogen dioxide and the ammonia gas can be more fully reacted.
In the present invention, the heating method employs electric heating or hot air heating. According to the characteristics of different industrial production; some plants produce large quantities of steam for power generation and the generated power can be used for electrical heating. Or directly heating the activated carbon by using an electric heating body. Hot air can also be used as a heat-conducting medium to heat the active carbon in-situ device.
In the present invention, the temperature of the regeneration process in step 3) is 200 to 600 ℃, preferably 250 to 520 ℃, preferably 300 to 480 ℃, and more preferably 350 to 450 ℃. And adjusting the temperature of the regeneration process according to the saturation degree of the activated carbon for adsorbing the pollutants, thereby adjusting the precipitation speed of the impurities in the activated carbon.
It should be noted that, the higher the heating temperature of the activated carbon adsorbing impurities is, the more violent the molecular motion of the impurities is, the easier the impurities break loose the constraint of the activated carbon, so that the speed of separating the impurities from the activated carbon is faster; the lower the heating temperature of the activated carbon adsorbing impurities is, the slower the molecular motion of the impurities is, the less easily the impurities break loose the constraint of the activated carbon, and thus the slower the separation speed from the activated carbon is. Under the condition of the same temperature, namely the certain molecular motion speed, the more the amount of pollutant impurities contained in the activated carbon is, the longer the complete regeneration time of the activated carbon is; under the condition of the same temperature, namely a certain molecular motion speed, the smaller the amount of pollutant impurities contained in the activated carbon is, the shorter the complete regeneration time of the activated carbon is. In addition, if the activated carbon is completely regenerated, the energy is only wasted by continuously heating at high temperature. Therefore, the temperature of the active carbon in-situ process needs to be adjusted according to the amount of impurities contained in the active carbon and the requirement of the process time, and the temperature adjustment range is as follows: 200-600 ℃.
In the invention, the sulfur resource of SRG gas is recovered, and sulfuric acid is prepared by an acid preparation process. Thereby reasonably utilizing resources, reducing the emission of sulfides and meeting the requirement of environmental protection.
It should be noted that the SRG gas mainly contains sulfur oxides such as SO2、SO3And the like. Dissolved in water to form sulfurous acid or sulfuric acid. Then the industrial sulfuric acid is produced by a redox method and a concentration method.
In the present invention, the SRG gas eventually contains no or a small amount of NH3. Small amount of NH3In the acid making process, ammonium sulfate is produced in combination with sulfuric acid.
According to the invention, after a part of activated carbon adsorbs nitrogen dioxide in advance, AC-NO is obtained2And mixed with activated carbon that has adsorbed contaminants (sulfur dioxide, ammonia, hydrogen chloride, etc.). AC-NO in regeneration process2Can release nitrogen dioxide, further can take place the SCR reaction with the ammonia that has adsorbed pollutant active carbon release to realize the elimination of ammonia, reduce ammonia concentration in the SRG flue gas, prevent to form ammonium chloride crystallization.
In the prior art, activated carbon is used for treating flue gas containing pollutants, physical adsorption is adopted, and simultaneously, the activated carbon provides a high-temperature environment. In order to remove the nitrogen oxides in the smoke containing the pollutants, namely to carry out denitration treatment, ammonia gas must be sprayed in the process, In order to ensure that the nitrogen oxides in the treated flue gas reach the emission standard, the adding amount of ammonia is excessive, so that the excessive ammonia is adsorbed by activated carbon to form AC-NH3The substance of (1). In addition, even if a proper amount or a little small amount of ammonia gas is added in the denitration process, the ammonia gas and the nitrogen oxide can not completely react, and part of the ammonia gas is still adsorbed by the activated carbon to form AC-NH3The substance of (1). Meanwhile, since the flue gas containing the pollutants, especially the sintering flue gas, contains part of the hydrogen halide (such as hydrogen chloride), the hydrogen halide is adsorbed by the activated carbon during the treatment of the activated carbon to form the substance of the AC-hydrogen halide (such as the substance of AC-HCl). The activated carbon absorbed with ammonia gas and hydrogen halide enters a regeneration process procedure, for example, a desorption tower (or a regeneration tower) is heated and regenerated, and then the activated carbon is recycled. In the regeneration step, the activated carbon having adsorbed ammonia gas and hydrogen halide releases the adsorbed ammonia gas and hydrogen halide, and the released ammonia gas and hydrogen halide enter the SRG gas and are transported to the sulfur resource recovery step. During the SRG gas conveying process, due to the reduction of the external temperature, ammonia gas is very easy to combine with hydrogen chloride to form ammonium halide crystal salt, and the ammonium halide crystal salt is deposited on an SRG gas conveying pipeline to cause the SRG gas to be blocked; meanwhile, hydrogen chloride is a strong acid and weak base salt, and the crystallization of the hydrogen chloride easily causes the corrosion of the SRG gas conveying pipeline. In addition, since the main component of the SRG gas is sulfur oxides, such as sulfur dioxide, which has a very high concentration, the sulfur oxides are also easily combined with ammonia gas to form crystals such as ammonium sulfate, which also causes blockage and corrosion of the SRG gas transportation pipeline.
In the regeneration process of the active carbon, the active carbon adsorbed with the pollutants is mixed with the active carbon pre-adsorbed with nitrogen dioxide, and the AC-NH in the active carbon adsorbed with the pollutants is mixed in the regeneration process at high temperature3The substances release ammonia gas, the activated carbon adsorbing nitrogen dioxide releases nitrogen dioxide, and the released ammonia gas reacts with the nitrogen dioxide to generate nitrogen gas and water vapor, so that the existence of the ammonia gas is eliminated or greatly reduced. The gas after reaction enters SRG gas, and ammonia gas is generated in the SRG gas conveying processThe concentration is greatly reduced, thereby avoiding the formation of ammonium chloride and ammonium sulfate crystals and realizing the prevention of the blockage and corrosion of SRG gas conveying pipelines.
Compared with the prior art, the technical scheme of the invention reduces the content of ammonia in the SRG gas by more than 90%. If the amount of carbon dioxide-adsorbed activated carbon is increased, the ammonia content of the SRG gas can be reduced by 95% or more. Because the concentration of ammonia in the SRG gas is greatly reduced, the formation of ammonium chloride and ammonium sulfate crystals is avoided even if the temperature of the SRG gas conveying pipeline is reduced.
Compared with the prior art, the invention has the following beneficial effects:
1. The scheme of the invention has the advantages of simple operation, high controllability, low cost and no secondary pollution;
2. according to the scheme, ammonium chloride crystallization in SRG can be inhibited, and stable operation of an active carbon flue gas purification system is guaranteed;
3. the scheme of the invention has the advantages of simple application and less modification to the original activated carbon flue gas purification system;
4. after the scheme of the invention is applied, the temperature of the SRG flue gas can be reduced, the scale of the SRG subsequent washing, cooling and purifying equipment is further reduced, and the investment cost is greatly reduced.
Drawings
FIG. 1 is a flow chart of the activated carbon flue gas purification process of the present invention;
FIG. 2 is a flow chart of a process for purifying flue gas by using activated carbon in the prior art;
FIG. 3 is a graph of crystallization temperature of ammonium chloride.
Detailed Description
According to an embodiment of the invention, there is provided a method of inhibiting SRG flue gas crystallization:
a method of inhibiting SRG flue gas crystallization, the method comprising the steps of:
1) and adsorbing nitrogen dioxide by using the activated carbon in advance to obtain the activated carbon I.
2) The activated carbon adsorbing the pollutants is marked as activated carbon II, and the activated carbon II is mixed with the activated carbon I obtained in the step 1).
3) And (3) carrying out a regeneration process on the mixture of the activated carbon II and the activated carbon I obtained in the step 2) to obtain SRG gas.
Preferably, the method further comprises: and 4) carrying out sulfur resource recovery on the SRG gas obtained in the step 3).
Preferably, after the regeneration process, the activated carbon II and the activated carbon I become fresh activated carbon, and are recycled to: step 1) for adsorbing nitrogen dioxide and/or step 2) for adsorbing contaminants.
Preferably, the amount of nitrogen dioxide adsorbed by the activated carbon in the activated carbon I in the step 1) is 30-100%, preferably 40-99%, more preferably 50-98%, and even more preferably 60-97% of the saturated adsorption amount of nitrogen dioxide by the activated carbon.
Preferably, the process conditions of the activated carbon pre-adsorbing nitrogen dioxide in the step 1) are as follows: normal temperature or higher than normal temperature and/or normal pressure or higher than normal pressure.
Preferably, the contaminants in step 2) originate from flue gases, preferably from sintering flue gases.
Preferably, the flue gas contains NOx and SO2One or more of dust, VOCs, heavy metals and halogen.
Preferably, the flue gas is flue gas containing nitrogen oxides and is derived from one or more of steel, electric power, nonferrous metal, petrochemical, chemical industry and building material industry.
Preferably, the temperature of the flue gas is 80-250 ℃, preferably 100-200 ℃, further preferably 120-180 ℃, and more preferably 130-160 ℃.
Preferably, the activated carbon II in the step 2) is activated carbon adsorbing pollutants, and ammonia gas is sprayed in the process of adsorbing the pollutants.
Preferably, the molar amount of the ammonia gas injected per unit time is 0.8 to 2 times, preferably 0.9 to 1.8 times, and more preferably 1.0 to 1.5 times the molar amount of NOx contained in the pollutants per unit time.
Preferably, the weight ratio of the activated carbon II in the step 2) to the activated carbon I obtained in the step 1) is 0.05 to 2 times, preferably 1:0.05 to 2, preferably 1:0.1 to 1.5, more preferably 1:0.2 to 1, and even more preferably 1:0.3 to 0.5.
Preferably, the regeneration in the step 3) is thermal regeneration, and the regeneration process is to heat the mixture of the activated carbon II and the activated carbon I.
Preferably, the heating is electric heating or hot air heating.
Preferably, the temperature of the regeneration process in step 3) is from 200 ℃ to 600 ℃, preferably from 250 ℃ to 520 ℃, preferably from 300 ℃ to 480 ℃, and more preferably from 350 ℃ to 450 ℃.
Preferably, the sulfur resource recovery of the SRG gas in the step 4) is a sulfuric acid production treatment of the SRG gas.
Preferably, the SRG gas contains no or very little NH 3。
Example 1
A method of inhibiting SRG flue gas crystallization, the method comprising the steps of:
1) and adsorbing nitrogen dioxide by using the activated carbon in advance to obtain the activated carbon I.
2) The activated carbon adsorbing the pollutants is marked as activated carbon II, and the activated carbon II is mixed with the activated carbon I obtained in the step 1).
3) And (3) carrying out a regeneration process on the mixture of the activated carbon II and the activated carbon I obtained in the step 2) to obtain SRG gas.
Example 2
Example 1 is repeated except that the method further comprises: and 4) carrying out sulfur resource recovery on the SRG gas obtained in the step 3).
Example 3
Example 2 was repeated except that after the regeneration process, activated carbon ii and activated carbon i were changed to fresh activated carbon, 30% of the cycle was used for adsorbing nitrogen dioxide in step 1), and the remaining 70% was used for adsorbing contaminants in step 2).
Example 4
Example 3 is repeated, except that the amount of nitrogen dioxide adsorbed by the activated carbon in the activated carbon I in the step 1) is 70% of the saturated adsorption amount of nitrogen dioxide adsorbed by the activated carbon.
Example 5
Example 4 is repeated, except that the process conditions of the activated carbon pre-adsorbing nitrogen dioxide in the step 1) are as follows: and (5) normal temperature. And (4) normal pressure.
Example 6
Example 5 was repeated, except that the contaminants in step 2) originated from sintering fumes.
Example 7
Example 6 was repeated except that the flue gas included NOx and SO2Dust, VOCs, heavy metals, halogen and the like.
Example 8
Example 7 was repeated except that the flue gas was a flue gas containing nitrogen oxides originating from the steel industry.
Example 9
Example 8 was repeated except that the temperature of the flue gas was 150 ℃.
Example 10
Example 9 is repeated, except that the activated carbon II in the step 2) is the activated carbon which adsorbs the pollutants, and ammonia gas is sprayed in the process of adsorbing the pollutants.
Example 11
Example 10 was repeated except that the molar amount of ammonia injected per unit time was 1.3 times the molar amount of NOx contained in the pollutants per unit time.
Example 12
Example 11 was repeated, except that the weight ratio of activated carbon II in step 2) to activated carbon I obtained in step 1) was 1: 0.4.
Example 13
Example 12 was repeated except that the regeneration in step 3) was thermal regeneration, and the regeneration process was a heat treatment of a mixture of activated carbon ii and activated carbon i.
Example 14
Example 13 was repeated except that the heating was carried out with hot air.
Example 15
Example 14 was repeated, except that the temperature of the regeneration process described in step 3) was 440 ℃.
Example 16
Example 15 was repeated except that the sulfur resource recovery of the SRG gas described in step 4) was to perform a sulfuric acid production treatment on the SRG gas.
Example 17
Example 16 was repeated except that the SRG gas did not contain NH3。
In the regeneration process of the active carbon, the active carbon adsorbed with the pollutants is mixed with the active carbon pre-adsorbed with nitrogen dioxide, and the AC-NH in the active carbon adsorbed with the pollutants is mixed in the regeneration process at high temperature3The substances release ammonia gas, the activated carbon adsorbing nitrogen dioxide releases nitrogen dioxide, and the released ammonia gas reacts with the nitrogen dioxide to generate nitrogen gas and water vapor, so that the existence of the ammonia gas is eliminated or greatly reduced. The gas after the reaction enters SRG gas, and in the SRG gas conveying process, the concentration of ammonia gas is greatly reduced, so that the formation of ammonium chloride and ammonium sulfate crystals is avoided, and the condition of preventing SRG gas conveying pipelines from being blocked and corroded is realized.
The concentration detection of ammonia gas is carried out on SRG gas generated by treating flue gas of a certain steel plant by adopting the prior art and SRG gas generated by treating flue gas of the steel plant by adopting the technical scheme of the invention, and the results are as follows:
| Content of Ammonia gas | |
| SRG gas produced by adopting the prior art | About 1000 to 20000ppm |
| The technical method of the inventionGenerated SRG gas | ＜50ppm |
Claims (10)
1. A method of inhibiting SRG flue gas crystallization, the method comprising the steps of:
1) adsorbing nitrogen dioxide by activated carbon in advance to obtain activated carbon I;
2) the activated carbon which adsorbs the pollutants is marked as activated carbon II, and the activated carbon II is mixed with the activated carbon I obtained in the step 1);
3) and (3) carrying out a regeneration process on the mixture of the activated carbon II and the activated carbon I obtained in the step 2) to obtain SRG gas.
2. The method of claim 1, wherein: the method further comprises the following steps: step 4) carrying out sulfur resource recovery on the SRG gas obtained in the step 3); and/or
After the regeneration process, the activated carbon II and the activated carbon I become fresh activated carbon, and the process is circulated to: step 1) for adsorbing nitrogen dioxide and/or step 2) for adsorbing contaminants.
3. The method according to claim 1 or 2, characterized in that: in the step 1), the amount of nitrogen dioxide adsorbed by the activated carbon in the activated carbon I is 30-100%, preferably 40-99%, further preferably 50-98%, and more preferably 60-97% of the saturated adsorption amount of the activated carbon to the nitrogen dioxide; and/or
The process conditions of the activated carbon for pre-adsorbing the nitrogen dioxide in the step 1) are as follows: normal temperature or higher than normal temperature and/or normal pressure or higher than normal pressure.
4. The method according to any one of claims 1-3, wherein: the pollutant in the step 2) is derived from flue gas, preferably from sintering flue gas; preferably, the flue gas contains NOx and SO2One or more of dust, VOCs, heavy metals and halogen.
5. The method of claim 4, wherein: the flue gas is flue gas containing nitrogen oxides generated by one or more of steel, electric power, nonferrous metals, petrifaction, chemical industry and building material industry; and/or
The temperature of the flue gas is 80-250 ℃, preferably 100-200 ℃, further preferably 120-180 ℃, and further preferably 130-160 ℃.
6. The method according to any one of claims 1-5, wherein: the activated carbon II in the step 2) is activated carbon adsorbing pollutants, and ammonia gas is sprayed in the process of adsorbing the pollutants; preferably, the molar amount of the ammonia gas injected per unit time is 0.8 to 2 times, preferably 0.9 to 1.8 times, and more preferably 1.0 to 1.5 times the molar amount of NOx contained in the pollutants per unit time.
7. The method according to any one of claims 1-6, wherein: the weight ratio of the activated carbon II in the step 2) to the activated carbon I obtained in the step 1) is 1: 0.05-2, preferably 1: 0.1-1.5, more preferably 1: 0.2-1, and more preferably 1: 0.3-0.5.
8. The method according to any one of claims 1-7, wherein: the regeneration in the step 3) is thermal regeneration, and the regeneration process is to heat the mixture of the activated carbon II and the activated carbon I; preferably, the heating is electric heating or hot air heating.
9. The method according to any one of claims 1-8, wherein: the temperature of the regeneration process in step 3) is 200-600 ℃, preferably 250-520 ℃, preferably 300-480 ℃, and more preferably 350-450 ℃.
10. The method according to any one of claims 2-9, wherein: the step 4) of recovering the sulfur resource of the SRG gas is to perform sulfuric acid preparation treatment on the SRG gas; and/or
The SRG gas contains no or little NH3。
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