Tail gas treatment process for coke oven gas HPF desulfurization regeneration tower and application of tail gas treatment process

Abstract

The invention discloses a coke oven gas HPF desulfurization regeneration tower tail gas treatment process and application, and belongs to the technical field of coke oven gas HPF desulfurization regeneration tower tail gas treatment, and the coke oven gas HPF desulfurization regeneration tower tail gas treatment process comprises the following steps: S1, washing coke oven gas HPF desulfurization regeneration tower tail gas to remove impurities, and then removing water after washing to obtain purified gas; s2, after the purified gas exchanges heat with steam, flue gas is formed; and S3, mixing the flue gas and the diluent gas to serve as an ammonia source, carrying out SCR denitration reaction on the ammonia source and nitrogen oxides in the SCR denitration original flue gas to remove the nitrogen oxides, and discharging clean flue gas. The process is applied to coke oven gas tail gas treatment, coke oven gas tail gas resource recovery or coke oven gas tail gas emission.

Description

Technical Field

[0001] The invention belongs to the technical field of tail gas treatment of a HPF desulfurization regeneration tower of coke oven gas, and in particular provides a tail gas treatment process and application of a HPF desulfurization regeneration tower of coke oven gas. Background Art

[0002] HPF regeneration tail gas treatment methods mainly include incineration, acid-base washing and ammonia decomposition, etc. These methods are aimed at reducing the emission of harmful substances. However, these methods usually bring secondary pollutants and have high energy consumption. In the HPF desulfurization regeneration tail gas, ammonia is the main pollutant. According to the special emission limit requirements for atmospheric pollutants in the "Coking Chemical Industry Pollutant Emission Standard" (GB16171-2012) and the ultra-low emission requirements of the coking industry, the ammonia emission requirements in the tail gas of the desulfurization regeneration tower are very strict and shall not exceed 10mg / m 3 In order to meet this standard, the present invention proposes a new HPF desulfurization tail gas regeneration treatment method, which can not only effectively purify the tail gas, but also stably control the ammonia emission concentration in the exhaust gas to 5mg / m 3 Next, the ammonia in the regenerated tail gas can also be utilized as a resource. Compared with the prior art, the tail gas regeneration treatment process of the present invention is more environmentally friendly, has lower costs, and can better reflect the concept of resource conservation and environmental friendliness. Summary of the invention

[0003] The present invention overcomes the above technical problems and provides a coke oven gas HPF desulfurization regeneration tower tail gas treatment process and application. The treatment process of the present invention utilizes ammonia in the coke oven gas HPF desulfurization regeneration tower tail gas as ammonia source for SCR denitration reaction, thereby realizing efficient resource utilization of ammonia. In addition, the process ensures that the utilization rate of ammonia and the SCR denitration efficiency reach a high level by accurately controlling the process parameters of each link, thereby improving the efficiency and environmental performance of the entire system.

[0004] The present invention solves the above technical problems through the following technical solutions.

[0005] A coke oven gas HPF desulfurization regeneration tower tail gas treatment process, comprising the following steps:

[0006] S1. The exhaust gas from the HPF desulfurization regeneration tower of coke oven gas is washed to remove impurities, and then the water after washing is removed to obtain purified gas;

[0007] S2. The purified gas exchanges heat with steam to form flue gas;

[0008] S3. Mix the flue gas and the dilution gas as an ammonia source, and then perform SCR denitration reaction with nitrogen oxides in the original flue gas to remove nitrogen oxides and discharge clean flue gas.

[0009] In the present invention, the SCR denitration reaction principle is:

[0010] In S1, the components of the tail gas of the HPF desulfurization regeneration tower of coke oven gas include: ammonia, hydrogen sulfide, hydrogen cyanide, and carbon monoxide; further, the components of the tail gas of the HPF desulfurization regeneration tower of coke oven gas include: 4500-10000 mg / m 3 Ammonia, 7-10 mg / m 3 Hydrogen sulfide, 8-10 mg / m 3 Hydrogen cyanide, 19 V / V% oxygen and 0.9 V / V% carbon monoxide.

[0011] In S1, the washing liquid used in the washing is concentrated ammonia water; preferably, the ammonia concentration in the washing liquid used in the washing is 15-30wt%, for example, 20wt%.

[0012] In S1, the washing temperature is 20-35°C.

[0013] In S1, the impurity removal can make hydrogen cyanide ≤ 2 mg / m 3 .

[0014] In S1, the impurities can be removed to make hydrogen sulfide ≤1mg / m 3 .

[0015] In S1, the purified gas includes 20000-50000 mg / m 3 ammonia.

[0016] In S2, the temperature of the flue gas is ≥120°C, preferably 140-300°C, such as 140°C or 150°C. Among them, when setting the operating temperature of the SCR denitration reactor, it is necessary to comprehensively consider the flue gas dew point, energy consumption, the applicable temperature range of the catalyst and the temperature of the original flue gas. First, ensure that the temperature is higher than the dew point of the flue gas to avoid condensation of moisture in the flue gas, which may cause equipment corrosion and catalyst deactivation. Secondly, consider the optimal operating temperature of the catalyst to achieve efficient denitration. At the same time, it is also necessary to weigh the energy consumption and select a temperature that can ensure the denitration efficiency without excessive energy consumption. Finally, consider the temperature of the original flue gas to reduce the need for additional heating or cooling.

[0017] In S2, the steam temperature is 300-600°C, preferably 400-450°C.

[0018] In S3, the dilution gas is air or clean flue gas. Using clean flue gas as the dilution gas can save energy consumption, avoid the energy consumed in the process of heating air, save the step of heating air, and improve the stability of system operation.

[0019] In S3, the temperature of the dilution gas is 160-200°C.

[0020] In S3, the temperature of the ammonia source is 120-300°C, preferably 150-300°C, for example 150°C. The temperature of the ammonia source needs to be above the dew point. Although appropriately increasing the temperature can improve the reaction efficiency, this usually leads to an increase in energy consumption. Therefore, in actual operation, a balance point is usually selected, that is, controlling energy consumption while ensuring efficiency.

[0021] In S3, the ammonia content in the clean flue gas is ≤5 mg / m 3 , preferably 0 to 3 mg / m 3 .

[0022] In S3, the nitrogen oxides in the clean flue gas are 50-150 mg / m 3 .

[0023] In S3, the components of the catalyst used in the SCR denitration include TiO2 and V2O5, preferably, in terms of mass percentage, include 80-85% TiO2, 1-3% V2O5 and 3-5% MoO3.

[0024] In S3, the space velocity of the catalyst of the SCR denitration reaction is ≤3800h -1 , for example 3600h -1 .

[0025] In S3, the ammonia slip rate in the SCR denitration reaction is 0-5%.

[0026] In the present invention, the denitration efficiency of the SCR denitration reaction is ≥88%, preferably 88.80-90.00%. Wherein, denitration efficiency = (1-total amount of nitrogen oxides in clean flue gas / total amount of nitrogen oxides in mixed gas) × 100%, and clean flue gas refers to the clean flue gas discharged by S3.

[0027] In the present invention, the ammonia utilization rate of the SCR denitration reaction is ≥ 97%, preferably 97.57-98.97%. Wherein, ammonia utilization rate = (total ammonia in clean flue gas / total ammonia in mixed gas) × 100%, and clean flue gas refers to the clean flue gas discharged by S3.

[0028] The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention comprises the following steps:

[0029] The tail gas from the HPF desulfurization regeneration tower of coke oven gas is washed in a washing tower, and then dehydrated by a mist collector to obtain purified gas; the purified gas is then indirectly heat-exchanged with steam in a heat exchanger to form flue gas; the flue gas and the dilution gas are mixed in an ammonia-air mixer to obtain an ammonia source; the ammonia source is passed through an ammonia spray grid and mixed with the SCR denitrification raw flue gas before entering the SCR denitrification reactor to obtain a mixed gas, and after the mixed gas enters the SCR denitrification reactor for SCR denitrification reaction, the SCR denitrification reactor discharges clean flue gas.

[0030] In the present invention, the flow rate of the tail gas from the HPF desulfurization regeneration tower entering the scrubbing tower is 3000-6000m 3 / h, for example 5000m 3 / h.

[0031] In the present invention, the total flow rate of all washing nozzles in the washing tower is 15-20m 3 / h.

[0032] In the present invention, the empty tower flow rate of the washing tower is 1.0-1.5 m / s, preferably 1.0-1.2 m / s.

[0033] In the present invention, the spray density of the washing tower is 12 to 17 m 3 / m 2 ·h -1 , preferably 12 to 15 m 3 / m 2 ·h -1 .

[0034] In the present invention, 1 to 2 layers of washing nozzles are arranged in the washing tower to ensure the washing effect.

[0035] In the present invention, a mist collector is provided at the top of the washing tower.

[0036] Furthermore, the gas pressure at the outlet of the mist collector is -1.2 to -1.5 Kpa.

[0037] Furthermore, the outlet flow rate of the mist collector is 5000-6000m 3 / h, for example 5000m 3 / h.

[0038] Furthermore, the droplet content at the outlet of the mist collector is 0 to 50 mg / m 3 , preferably 30-40 mg / m 3 Among them, the droplets at the outlet of the mist collector are mainly water, and also contain a small amount of salt substances (salts generated by the reaction of ammonia with hydrogen sulfide and cyanide); in order to solve the problem of pipeline corrosion and increased energy consumption of the evaporator caused by excessive water content in the HPF desulfurization tail gas of coke oven gas after washing, a mist collector can be added to the system to reduce the moisture content of the regenerated tail gas;

[0039] In the present invention, the flow rate of the ammonia source entering the SCR denitration reactor through the ammonia injection grid is 6000-7000m 3 / h.

[0040] In the present invention, the temperature of the mixed gas entering the SCR denitration reactor is 260-300°C, such as 270°C, 280°C or 290°C.

[0041] In the present invention, the molar ratio of ammonia to nitrogen oxides in the mixed gas is ≤1.

[0042] In the present invention, the mixed gas contains 150-600 mg / m 3 Nitrogen oxides and 50~200mg / m 3 Ammonia; for example, containing 550 mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0043] The present invention also provides the application of the aforementioned coke oven gas HPF desulfurization regeneration tower tail gas treatment process in coke oven gas tail gas treatment, coke oven gas tail gas resource recovery or coke oven gas tail gas emission.

[0044] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] In terms of resource utilization, the present invention uses ammonia in the tail gas of the coke oven gas desulfurization regeneration tower as the ammonia source for SCR denitrification, thereby realizing resource utilization of ammonia and reducing ammonia emissions and environmental pollution. Among them, the ammonia utilization rate is ≥97%, and the denitrification efficiency is ≥88%.

[0047] In terms of treatment process, the present invention adopts concentrated ammonia water as washing liquid, removes impurities in the tail gas, such as hydrogen sulfide, hydrogen cyanide, etc. through a multi-stage washing system, and recovers ammonia at the same time; by strictly controlling the gas composition and temperature of each link and adjusting the SCR denitrification process, it is ensured that environmental protection standards are met. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the process flow chart of the tail gas treatment process of the HPF desulfurization regeneration tower of coke oven gas.

[0049] Explanation of the reference numerals: 1. washing tower, 2. mist collector, 3. washing nozzle, 4. washing liquid circulation pump, 5. heat exchanger, 6. booster fan, 7. ammonia-air mixer, 8. ammonia spray grid, 9. SCR denitrification reactor, 10. SCR denitrification raw flue gas, 11. ammonia evaporator (spare), 12. coke oven gas HPF desulfurization regeneration tower tail gas, 13. desulfurization liquid system, 14. dilution gas.

[0050] Note: The ammonia evaporator (spare) is mainly used to consider that in actual engineering applications, the concentration of nitrogen oxides in the raw flue gas of SCR denitrification and the concentration of ammonia in the tail gas of HPF desulfurization regeneration tower will change. When the concentration of nitrogen oxides in the raw flue gas of SCR denitrification increases and the tail gas of HPF desulfurization regeneration tower of coke oven gas decreases, the problem of insufficient ammonia may be faced. At this time, the ammonia evaporator can be used to supplement ammonia to ensure that the nitrogen oxides at the outlet of the system are stable and meet the standards. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0053] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0055] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0056] If not otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0057] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0058] If not specifically stated, in the present invention, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0059] The catalyst for the SCR denitration reaction in the following examples or comparative examples was purchased from Anhui Fangxin Lihua Environmental Protection Technology Co., Ltd. The catalyst includes 85% TiO2, 3% V2O5 and 4% MoO3; the specification is 30mm×30mm, and it is a honeycomb catalyst.

[0060] Example 1

[0061] 1. Coke oven gas HPF desulfurization regeneration tower tail gas treatment process:

[0062] The components of the tail gas from the HPF desulfurization regeneration tower of coke oven gas include: 4500~10000mg / m 3 Ammonia, 7-10 mg / m 3 Hydrogen sulfide, 10mg / m 3 Hydrogen cyanide, 19 V / V% oxygen and 0.9 V / V% carbon monoxide.

[0063] S1. The tail gas from the HPF desulfurization regeneration tower of coke oven gas is washed at 25°C (the washing liquid is 20% concentrated ammonia water) to remove impurities; the hydrogen cyanide content is 1.2 mg / m 3 , hydrogen sulfide content is 0.8mg / m 3 ; Then remove the water after washing to obtain purified gas; the purified gas contains 20000~50000mg / m 3 ammonia.

[0064] S2. The purified gas is heat exchanged with steam at 400-450℃ to form flue gas, and the flue gas temperature is 140℃.

[0065] S3. Mix the flue gas and dilution gas (hot air with a temperature of 160-200°C) as an ammonia source, the temperature of the ammonia source is 150°C; the ammonia source then reacts with the nitrogen oxides in the SCR denitrification flue gas to undergo SCR denitrification reaction, and the space velocity of the catalyst for the SCR denitrification reaction is 3600h -1 , ammonia escape rate is 1.03%; nitrogen oxides are removed and clean flue gas is emitted; the ammonia concentration in the clean flue gas is 1.9mg / m 3 、Nitrogen oxides 55mg / m 3 .

[0066] 2. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0067] The tail gas of the HPF desulfurization regeneration tower of coke oven gas is washed in a washing tower (1), and after washing, it is dehydrated by a mist collector (2) to obtain purified gas; the purified gas is then indirectly heat-exchanged with steam (or high-temperature exhaust gas) in a heat exchanger (5) to form flue gas; the flue gas and the dilution gas are mixed in an ammonia-air mixer (7) to obtain an ammonia source; the ammonia source is passed through an ammonia spraying grid (8), and before entering an SCR denitration reactor (9), it is mixed with the SCR denitration raw flue gas to obtain a mixed gas; after the mixed gas enters the SCR denitration reactor (9) for SCR denitration reaction, the SCR denitration reactor (9) discharges clean flue gas.

[0068] In this embodiment, the flow rate of the tail gas from the HPF desulfurization regeneration tower of coke oven gas entering the scrubber is 5000m 3 / h, temperature is 35℃;

[0069] In this embodiment, the total flow rate of all washing nozzles in the washing tower is 15-20m 3 / h.

[0070] In this embodiment, the empty tower flow rate of the washing tower is 1.2 m / s.

[0071] In this embodiment, the spray density of the washing tower is 12-15m 3 / m 2 ·h -1When the total flow rate of all washing nozzles in the washing tower is large, the spray density of the washing tower will also increase accordingly.

[0072] In this embodiment, two layers of washing nozzles are arranged in the washing tower.

[0073] In this embodiment, a mist collector is provided on the top of the scrubbing tower; the droplet content at the outlet of the mist collector is 30-40 mg / m 3 The gas pressure at the mist collector outlet is -1.2 to -1.5 Kpa, and the mist collector outlet flow rate is 5000m 3 / h.

[0074] In this embodiment, the flow rate of the ammonia source entering the SCR denitration reactor through the ammonia injection grid is 6000-7000m 3 / h.

[0075] In this embodiment, the mixed gas contains 550 mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0076] In this embodiment, the temperature of the mixed gas entering the SCR denitration reactor is 280°C.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that:

[0079] 2. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0080] In this embodiment, the temperature of the mixed gas entering the SCR denitration reactor is 290°C. The mixed gas contains 550 mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0081] The ammonia concentration in the clean flue gas in S3 is 2.1 mg / m 3 、Nitrogen oxides 55.1mg / m 3 .

[0082] Example 3

[0083] The difference between this embodiment and embodiment 1 is that:

[0084] 1. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0085] In this embodiment, the dilution gas in S2 is clean flue gas with a temperature of 275°C;

[0086] The mixed gas contains 550mg / m 3Nitrogen oxides and 185mg / m 3 ammonia.

[0087] The ammonia concentration in the clean flue gas in S3 is 1.8 mg / m 3 、Nitrogen oxides 54.3mg / m 3 .

[0088] Example 4

[0089] The difference between this embodiment and embodiment 1 is that:

[0090] 2. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0091] In this embodiment, the temperature of the mixed gas entering the SCR denitration reactor is 270°C. The mixed gas contains 550 mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0092] The ammonia concentration in the clean flue gas in S3 is 4.5 mg / m 3 、Nitrogen oxides 61.59mg / m 3 .

[0093] Example 5

[0094] The difference between this embodiment and embodiment 1 is that:

[0095] 1. Coke oven gas HPF desulfurization regeneration tower tail gas treatment process:

[0096] The space velocity of SCR denitration catalyst in S3 is 3800h -1 .

[0097] The mixed gas contains 550mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0098] The ammonia concentration in the clean flue gas in S3 is 2.5 mg / m 3 、Nitrogen oxides 56.2mg / m 3 .

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 1 is:

[0101] 2. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0102] In this comparative example, the temperature of the mixed gas entering the SCR denitration reactor is 250°C.

[0103] The mixed gas contains 550mg / m3 Nitrogen oxides and 185mg / m 3 ammonia.

[0104] The ammonia concentration in the clean flue gas is 39.8 mg / m 3 、Nitrogen oxides 157.1mg / m 3 .

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 1 is:

[0107] 1. Coke oven gas HPF desulfurization regeneration tower tail gas treatment process:

[0108] In S3, the SCR denitration catalyst space velocity is 7000h -1 .

[0109] The ammonia slip rate in S3 was 11.7%.

[0110] The mixed gas contains 550mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0111] The ammonia concentration in the clean flue gas in S3 is 21.6 mg / m 3 、Nitrogen oxides 107.9mg / m 3 .

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is:

[0114] 1. Coke oven gas HPF desulfurization regeneration tower tail gas treatment process:

[0115] S1. Wash the tail gas from the HPF desulfurization regeneration tower of coke oven gas at 25°C (the washing liquid is water) to remove impurities; make the hydrogen cyanide content 6-7 mg / m 3 , hydrogen sulfide content is 5-6 mg / m 3 ; Then remove the water after washing to obtain purified gas; the purified gas contains 1500-2000mg / m 3 ammonia.

[0116] The mixed gas contains 550mg / m 3 Nitrogen oxides and 19.8mg / m 3 ammonia.

[0117] The ammonia concentration in the clean flue gas in S3 is 0.9 mg / m 3 、Nitrogen oxides 498.9mg / m 3 .

[0118] Comparative Example 4

[0119] The difference between this comparative example and Example 1 is:

[0120] 2. The process of the HPF desulfurization regeneration tower tail gas treatment process of coke oven gas in the present invention:

[0121] The droplet content at the outlet of the mist collector is 300mg / m 3 .

[0122] The mixed gas contains 550mg / m 3 Nitrogen oxides and 185mg / m 3 ammonia.

[0123] The ammonia concentration in the clean flue gas in S3 is 18.8 mg / m 3 、Nitrogen oxides 100.3mg / m 3 .

[0124] Effect Example

[0125] The ammonia utilization rate and SCR denitrification efficiency results in the above examples and comparative examples are shown in Table 1.

[0126] Table 1

[0127] - Ammonia utilization rate (%) Denitrification efficiency (%) Example 1 98.97 90.00 Example 2 98.86 89.98 Example 3 99.03 90.13 Example 4 97.57 88.80 Example 5 98.65 89.78 Comparative Example 1 78.49 71.44 Comparative Example 2 88.32 80.38 Comparative Example 3 95.45 9.29 Comparative Example 4 89.84 81.76

[0128] According to the above comparative examples and embodiments and the results in Table 1, it can be seen that:

[0129] In Comparative Example 1, in the SCR denitration reactor, the reason for the decrease in ammonia utilization is mainly that when the reaction temperature is low, ammonium bisulfate is easily formed. This substance has a very high viscosity and will adhere to the surface of the catalyst, resulting in clogging of the catalyst pore structure and coverage of surface active sites, thereby hindering the full contact between ammonia and the catalyst. In addition, the formation of ammonium bisulfate will also lead to an increase in the local flue gas flow rate inside the catalyst, which not only reduces the utilization rate of ammonia, but also increases the escape rate of ammonia. At the same time, when the temperature of the SCR reactor is low, the denitration efficiency will also decrease. This is because at this temperature, the formation of ammonium bisulfate not only reduces the utilization rate of ammonia, but also affects the catalytic effect of the catalyst. The catalyst activity decreases at low temperatures, and the reaction between ammonia and nitrogen oxides cannot be effectively promoted, resulting in a decrease in denitration efficiency. In addition, the low temperature fails to reach the temperature range in which the catalyst exerts an efficient catalytic effect, further affecting the catalytic effect of the catalyst and the overall denitration performance.

[0130] In Comparative Example 2, in the SCR denitration system, the efficiency decreases mainly due to the excessive space velocity of the catalyst, which shortens the contact time between the ammonia gas and the catalyst and increases the risk of catalyst wear and blockage, thereby reducing the denitration efficiency, increasing the escape amount of ammonia, and resulting in a decrease in the utilization rate of ammonia.

[0131] In Comparative Example 3, the washing liquid of the HPF desulfurization regeneration tower tail gas uses clean water. The content of hydrogen cyanide and hydrogen sulfide in the tail gas after impurities are basically the same as those in Example 1. However, since ammonia is easily soluble in water, the use of clean water for washing will remove a large amount of ammonia in the tail gas, thereby reducing the denitration efficiency. In order to improve the denitration efficiency, it is recommended to use concentrated ammonia water for washing. The advantage of using concentrated ammonia water is that the coke oven gas purification process can usually produce concentrated ammonia water by itself, which can greatly save operating costs. In addition, the concentrated waste liquid produced after washing can be directly added to the desulfurization liquid of the HPF coke oven gas desulfurization, and used as an alkali source for coke oven gas desulfurization, avoiding the problem of waste disposal. In this way, the utilization rate of ammonia will not be affected.

[0132] In Comparative Example 4, the reason for the decrease in SCR denitration efficiency is that water vapor and ammonia are competitively adsorbed on the catalyst surface. Due to the adsorption of water vapor on the catalyst surface, it competes with ammonia for limited active sites, which limits the effective contact and reaction between ammonia and nitrogen oxides. Since ammonia is a key reductant in the SCR denitration reaction, its reaction with nitrogen oxides is inhibited, resulting in a decrease in denitration efficiency.

[0133] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A coke oven gas HPF desulfurization regeneration tower tail gas treatment process, characterized in that: The following steps are involved: S1. The exhaust gas from the HPF desulfurization regeneration tower of coke oven gas is washed to remove impurities, and then the water after washing is removed to obtain purified gas; S2. The purified gas exchanges heat with steam to form flue gas; S3. Mix the flue gas and the dilution gas as an ammonia source, and then perform SCR denitration reaction with nitrogen oxides in the original flue gas to remove nitrogen oxides and discharge clean flue gas.

2. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 1, characterized in that: The components of the tail gas from the HPF desulfurization regeneration tower of coke oven gas include: 4500-10000 mg / m 3 Ammonia, 7-10 mg / m 3 Hydrogen sulfide, 8-10 mg / m 3 Hydrogen cyanide, 19 V / V% oxygen and 0.9 V / V% carbon monoxide.

3. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 2, characterized in that: The S1 satisfies at least one of the following conditions ① to ⑤: ① The washing liquid used in the washing is concentrated ammonia water; ② The washing temperature is 20-35°C; ③ The removal of impurities can make hydrogen cyanide ≤ 2mg / m 3 ; ④ The removal of impurities can make hydrogen sulfide ≤1mg / m 3 ; ⑤ The purified gas includes 20000~50000mg / m 3 ammonia.

4. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 2, characterized in that: The temperature of the flue gas is ≥ 120°C And / or, the steam temperature is 300-600°C.

5. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 2, characterized in that: S3 satisfies at least one of the following conditions ① to ⑧: ① The dilution gas is air or clean flue gas; ② The temperature of the dilution gas is 160-200°C; ③ The temperature of the ammonia source is between 120 and 300°C ④ The ammonia in the clean flue gas is ≤5mg / m 3 ; ⑤ The nitrogen oxides in the clean flue gas are 50-150 mg / m 3 ; ⑥ The components of the catalyst used in the SCR denitration include TiO2 and V2O5; ⑦ The space velocity of the catalyst for the SCR denitration reaction is ≤3800h -1 ; ⑧ The ammonia escape rate in the SCR denitration reaction is 0-5%.

6. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 1, characterized in that: Satisfy at least one of the following conditions ①~②: ① The denitration efficiency of the SCR denitration reaction is ≥88%; ② The ammonia utilization rate of the SCR denitration reaction is ≥97%.

7. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 1, characterized in that: The process of the coke oven gas HPF desulfurization regeneration tower tail gas treatment process comprises the following steps: The tail gas from the HPF desulfurization regeneration tower of coke oven gas is washed in a washing tower, and then dehydrated by a mist collector to obtain purified gas; the purified gas is then indirectly heat-exchanged with steam in a heat exchanger to form flue gas; the flue gas and the dilution gas are mixed in an ammonia-air mixer to obtain an ammonia source; the ammonia source is passed through an ammonia spray grid and mixed with the SCR denitrification raw flue gas before entering the SCR denitrification reactor to obtain a mixed gas, and after the mixed gas enters the SCR denitrification reactor for SCR denitrification reaction, the SCR denitrification reactor discharges clean flue gas.

8. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 7, characterized in that: Satisfy at least one of the following conditions ① to ⑨: ① The flow rate of the tail gas from the coke oven gas HPF desulfurization regeneration tower entering the scrubber is 5000m 3 / h ② The total flow rate of all washing nozzles in the washing tower is 15-20m 3 / h; ③ The empty tower flow rate of the washing tower is 1.0-1.5 m / s; ④The spray density of the washing tower is 12~17m 3 / m 2 ·h -1 ; ⑤ A mist collector is provided on the top of the washing tower; ⑥ The flow rate of the ammonia source entering the SCR denitration reactor through the ammonia injection grid is 6000-7000m 3 / h; ⑦ The temperature of the mixed gas entering the SCR denitration reactor is 260-300°C; ⑧ The molar ratio of ammonia to nitrogen oxides in the mixed gas is ≤1; ⑨ The mixed gas contains 150-600 mg / m 3 Nitrogen oxides and 50~200mg / m 3 ammonia.

9. The process for treating tail gas from a coke oven gas HPF desulfurization regeneration tower according to claim 7, characterized in that: Satisfy at least one of the following conditions ① to ③: ① The gas pressure at the outlet of the mist collector is -1.2~-1.5Kpa; ② The outlet flow rate of the mist collector is 5000~6000m 3 / h; ③ The droplet content at the outlet of the mist collector is 0-50 mg / m 3 .

10. Application of the coke oven gas HPF desulfurization regeneration tower tail gas treatment process according to any one of claims 1 to 9, characterized in that: Application in coke oven gas tail gas treatment, coke oven gas tail gas resource recovery or coke oven gas tail gas emission.

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