Method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in gas phase

Abstract

The invention relates to a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase, which comprises the following steps: reversely contacting the gas phase with an organic amine mixed solution for absorption to obtain a purified gas phase and an amine-rich solution; wherein the organic amine mixed solution is prepared from monoethanolamine, N-methyldiethanolamine and ethylenediamine. The device can realize efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption process, only needs a single absorption device, and has the advantages of small occupied area and simple equipment.

Description

Technical Field

[0001] The invention relates to the technical field of coke oven gas desulfurization and decarbonization / coke oven gas purification, and in particular to a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase. Background Art

[0002] Coke oven gas is a combustible gas produced as a byproduct when raw coal is carbonized in a coke oven to produce coke at high temperature. Its main components are hydrogen (55-60%) and methane (23-27%). It also contains a small amount of carbon monoxide (5-8%), unsaturated hydrocarbons (2-4%), carbon dioxide (1.5-3%), oxygen (0.3-0.8%), nitrogen (3-7%), hydrogen sulfide (2-4g / m 3 ), carbonyl sulfide (100-200 mg / m 3 ). Coke oven gas is a medium calorific value gas with a calorific value of 17-19MJ per standard cubic meter. It is suitable for use as fuel for high-temperature industrial furnaces and city gas. Coke oven gas has a high hydrogen content and can be used for synthetic ammonia after separation. Other components such as methane and ethylene can be used as raw materials for organic synthesis. Hydrogen sulfide, carbon dioxide and carbonyl sulfide in coke oven gas have a negative impact on the high-value utilization of coke oven gas, which may cause catalyst deactivation, pipeline blockage, etc. Therefore, the purification of coke oven gas is mainly aimed at the removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide.

[0003] CN102086417A discloses a process for purifying biogas and recovering elemental sulfur and carbon dioxide. The third step of the process is gas purification, decarbonization and desulfurization, which is specifically: the pressurized biogas is passed into an absorption tower, and in the absorption tower, it is countercurrently contacted with an organic amine absorption liquid from top to bottom, and the carbon dioxide and hydrogen sulfide in the biogas are absorbed by the organic amine alkaline absorption liquid. The purified high-purity biogas is cooled by the absorption tower cooler, separated and dehydrated by the absorption tower separator, and then pressurized and sent out as vehicle fuel. The organic amine alkali liquid containing hydrogen sulfide and carbon dioxide is heated in a heat exchanger and sent to a desorption tower for heating and desorption. The mixed gas of carbon dioxide and hydrogen sulfide is cooled by the desorption tower cooler, and after the desorption tower separator is dehydrated, it is sent to the Clinsulf reactor to oxidize hydrogen sulfide. It can only remove hydrogen sulfide and carbon dioxide at the same time, and cannot achieve the simultaneous removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide.

[0004] CN112473742A discloses a desulfurization catalyst for simultaneously removing hydrogen sulfide and carbonyl sulfide and a preparation method thereof. The catalyst of the method comprises: metal chelate salt, organic amine, organic alcohol, mixed oxide and sodium carbonate. The catalyst can simultaneously remove hydrogen sulfide and carbonyl sulfide and can effectively remove them to a content of less than 20 mg / m 3 However, this method cannot remove carbon dioxide, and cannot achieve the simultaneous removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide.

[0005] CN106540511A discloses a method for removing hydrogen sulfide from gas using an organic solvent system. The solvent of the method is a mixture of alkane substances and organic amine substances. The method is used to treat relatively high-pressure natural gas, oilfield associated gas and other gases. However, the method cannot remove carbon dioxide and cannot achieve the simultaneous removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide.

[0006] In summary, it is necessary to develop a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, so that the removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide can be achieved in the same absorption process to reduce the footprint and promote the possibility of promoting this process method in the existing coke oven gas purification facilities. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. By selecting a specific organic amine mixed liquid, the present invention can simultaneously remove hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, and at the same time, the absorbed rich amine liquid can be desorbed and recycled.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase, the method comprising: bringing the gas phase into reverse contact with an organic amine mixed liquid for absorption to obtain a purified gas phase and an amine-rich liquid;

[0010] Wherein, the organic amine mixture includes monoethanolamine, N-methyldiethanolamine and ethylenediamine.

[0011] The reaction principle of the present invention is:

[0012] CO2+Amine→Amine-CO2,

[0013] Amine-CO2+H2O→AmineH + +HCO3 - ,

[0014] H2S+Amine→Amine-H2S,

[0015] H2S+Amine→AmineH + +HS - ,

[0016] HS - →H + +S 2- ,

[0017] Amine-H2O→AmineH ++AmineOH - ,

[0018] COS+AmineOH - →Amine-HSCO2 - ,

[0019] AmineH + +Amine-HSCO2 - →CO2+H2S

[0020] AmineH + +OH - →H2O+Amine,

[0021] Amine represents organic amine.

[0022] The present invention limits the organic amine mixed liquid to include monoethanolamine, N-methyldiethanolamine and ethylenediamine. When the coke oven gas and the organic amine mixed liquid are in reverse contact for absorption, hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase can be removed simultaneously to obtain a purified gas phase and an amine-rich liquid, wherein monoethanolamine (MEA) has a fast absorption rate and a large absorption capacity and is the main absorbent, and its reaction product with CO2 is carbamate. Although the addition of ethylenediamine cannot increase the absorption rate, it can increase the absorption capacity, and due to the steric hindrance generated by the connection between the amino group and the secondary carbon, the carbamate is easier to decompose, thereby reducing the energy consumption of regeneration. N-methyldiethanolamine is a tertiary alcohol amine, which plays a role similar to a catalyst in the reaction process, that is, the hydrogen bond formed between the free amine and water enhances the activity of the reaction between water and CO2, thereby promoting the hydration of CO2. That is, monoethanolamine, N-methyldiethanolamine and ethylenediamine cooperate with each other to simultaneously remove hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, so that the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide can be completed in a single absorption device.

[0023] Coke oven gas is a combustible gas produced as a byproduct when raw coal is carbonized in a coke oven to produce coke at high temperature. Its main components are hydrogen (55-60%) and methane (23-27%). It also contains a small amount of carbon monoxide (5-8%), unsaturated hydrocarbons (2-4%), carbon dioxide (1.5-3%), oxygen (0.3-0.8%), nitrogen (3-7%), hydrogen sulfide (2-4g / m 3 ), carbonyl sulfide (100-200 mg / m 3 ).

[0024] As a preferred technical solution of the present invention, the mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine is (40-60):(10-30):(20-40), for example, it can be 40:10:20, 50:10:20, 60:10:20, 50:20:20, 50:30:20, 50:20:30, 50:20:40 or 60:30:40, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] The present invention limits the mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine to (40-60):(10-30):(20-40), thereby ensuring efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device. If the mass ratio is too small, the absorption rate of CO2 will be too low, and efficient removal of CO2 cannot be achieved. If the mass ratio is too large, the steric hindrance is large, resulting in low regeneration efficiency.

[0026] As a preferred technical solution of the present invention, the mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine is (45-55):(15-25):(25-35), for example, it can be 45:15:25, 50:15:25, 55:15:25, 50:20:25:, 50:20:35, 50:25:30, 50:20:35 or 55:25:35, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0027] As a preferred technical solution of the present invention, the temperature of the gas phase in the absorption is 35-50°C, for example, it can be 35°C, 37°C, 39°C, 40°C, 41°C, 43°C, 45°C, 47°C, 49°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0028] The present invention can ensure the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device by controlling the temperature of the gas phase to 35-50°C during the absorption process. If the temperature is too high, it will lead to increased technical energy consumption and waste of energy. If the temperature is too low, the absorption rate will decrease, which will lead to reduced removal efficiency.

[0029] Preferably, the liquid-to-gas ratio of the absorption is (5-8):1, for example, it can be 5:1, 6:1, 7:1 or 8:1, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0030] The present invention can ensure efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device by controlling the liquid-gas ratio during the absorption process to (5-8):1. If the liquid-gas ratio during the absorption process is less than 5:1, the removal efficiency will be reduced. If the liquid-gas ratio during the absorption process is greater than 8:1, the tower will be flooded, causing a sudden increase in the resistance of the absorption tower.

[0031] As a preferred technical solution of the present invention, the temperature of the rich amine solution is 35-50°C, for example, 35°C, 40°C, 45°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0032] Preferably, the temperature of the heated rich amine solution is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the above range are also applicable.

[0033] The present invention limits the temperature of the heated rich amine liquid to 60-80°C, which can make the temperature of the heated rich amine liquid close to the operating temperature of the desorption tower, which is beneficial to the desorption process. If the temperature is too high, it will lead to excessive energy consumption and waste of resources.

[0034] As a preferred technical solution of the present invention, the method further comprises: heating the rich amine liquid and performing desorption to obtain a desorbed gas phase and a lean amine liquid;

[0035] The lean amine liquid is cooled and then recycled in the absorption reaction.

[0036] The present invention can select a specific organic amine mixed liquid so that the rich amine liquid after absorption can be desorbed to obtain lean amine liquid. Since the desorption temperature is higher than the absorption temperature, the lean amine liquid can be recycled in the absorption reaction after cooling.

[0037] Preferably, the desorption heating form includes hot steam heating or hot nitrogen.

[0038] Preferably, the desorption temperature is 90-95°C, for example, 90°C, 91°C, 92°C, 93°C, 94°C or 95°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0039] The present invention limits the desorption temperature to 90-95°C, and can desorb the rich amine liquid to obtain the lean amine liquid for recycling. If the temperature is too low, it will lead to incomplete regeneration and reduced absorption efficiency. If the temperature is too high, it will cause the organic amine to decompose.

[0040] As a preferred technical solution of the present invention, the desorption process of the desorption includes thermal regeneration.

[0041] Preferably, the desorption time is 5-10 min, for example, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0042] As a preferred technical solution of the present invention, the temperature of the lean amine liquid after cooling is 35-50°C, for example, it can be 35°C, 37°C, 39°C, 40°C, 41°C, 43°C, 45°C, 47°C, 49°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0043] As a preferred technical solution of the present invention, the circulation volume of the lean amine solution is 50-100m 3 / h, for example, 50m 3 / h、60m 3 / h、70m 3 / h、80m 3 / h、90m 3 / h or 100m 3 / h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0044] The present invention limits the circulation volume of lean amine solution to 50-100m 3 / h. If the circulation volume is too small, it will lead to insufficient absorption and reduced removal efficiency. If the circulation volume is too large, it will cause tower flooding and a sudden increase in the pressure drop of the absorption tower.

[0045] Preferably, before the lean amine liquid is circulated, any one of monoethanolamine, N-methyldiethanolamine or ethylenediamine or a combination of at least two thereof is supplemented to the lean amine liquid, and the mass ratio of monoethanolamine:N-methyldiethanolamine:ethylenediamine is adjusted to (40-60):(10-30):(20-40). Typical but non-limiting combinations of supplementary liquids in the lean amine liquid include: a combination of monoethanolamine and N-methyldiethanolamine, a combination of monoethanolamine and ethylenediamine, a combination of N-methyldiethanolamine and ethylenediamine, and a combination of monoethanolamine, N-methyldiethanolamine and ethylenediamine. The mass ratio can be adjusted to 40:10:20, 50:10:20, 60:10:20, 50:20:20, 50:30:20, 50:20:30, 50:20:40 or 60:30:40, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0046] As a preferred technical solution of the present invention, the method comprises: monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of (40-60):(10-30):(20-40) to obtain an organic amine mixed liquid, the organic amine mixed liquid is reversely contacted with a gas phase at 35-50° C. for absorption, the liquid-to-gas ratio of the absorption is (5-8):1, and a purified gas phase and a rich amine liquid at a temperature of 35-50° C. are obtained;

[0047] The rich amine liquid is heated to 60-80° C. and then desorbed to obtain desorbed gas and lean amine liquid, wherein the desorption temperature is 90-95° C.;

[0048] The lean amine liquid is cooled to 35-50° C., any one of monoethanolamine, N-methyldiethanolamine or ethylenediamine or a combination of at least two thereof is added to the lean amine liquid, the mass ratio of monoethanolamine:N-methyldiethanolamine:ethylenediamine is adjusted to (40-60):(10-30):(20-40), and then the lean amine liquid is recycled in the absorption reaction.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] The present invention can realize the simultaneous removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption process, only requires a single absorption device, reduces the occupied area, and can make the removal rate of hydrogen sulfide reach more than 95%, the removal rate of carbon dioxide reach more than 90%, and the removal rate of carbonyl sulfide reach more than 95%, thereby promoting the possibility of promoting the process in the built coke oven gas purification facilities, and the overall technical and economic advantages are very obvious; at the same time, the organic amine mixed liquid after use can be recycled, reducing the generation of wastewater and waste, which is in line with the current trend of waste-free pollution control. DETAILED DESCRIPTION

[0051] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] The gas phase used in the following examples is coke oven gas, which mainly contains hydrogen (56%) and methane (24%), and also contains small amounts of carbon monoxide (5%), unsaturated hydrocarbons (4%), carbon dioxide (3%), oxygen (0.8%), nitrogen (3%), hydrogen sulfide (4 g / m 3 )、Carbonyl sulfide (200mg / m 3 ). However, this does not mean that the present invention is only applicable to the gas phase with the above composition, and the gas phase containing hydrogen sulfide, carbon dioxide and carbonyl sulfide at the same time can be treated.

[0053] Example 1

[0054] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase, the method comprising:

[0055] Monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 50:20:30 to obtain an organic amine mixed liquid, and the organic amine mixed liquid is reversely contacted with a gas phase at 40° C. for absorption, and the absorption liquid-to-gas ratio is 6:1 to obtain a purified gas phase and a rich amine liquid at a temperature of 40° C.;

[0056] The rich amine liquid is heated to 70° C. and then desorbed for 7 minutes to obtain desorbed gas and lean amine liquid. The desorption heating method is hot steam heating, and the desorption temperature is 92° C.;

[0057] The lean amine liquid is cooled to 40° C., monoethanolamine, N-methyldiethanolamine and ethylenediamine are added to the lean amine liquid, and the mass ratio of monoethanolamine: N-methyldiethanolamine: ethylenediamine is adjusted to 50:20:30, and the lean amine liquid is recycled in the absorption reaction, with a circulation volume of 70m 3 / h.

[0058] Example 2

[0059] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase, the method comprising:

[0060] Monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 45:15:25 to obtain an organic amine mixed liquid, and the organic amine mixed liquid is reversely contacted with a gas phase at 35° C. for absorption, and the absorption liquid-to-gas ratio is 8:1 to obtain a purified gas phase and a rich amine liquid at a temperature of 35° C.;

[0061] The rich amine liquid is heated to 60° C. and then desorbed for 10 minutes to obtain desorbed gas and lean amine liquid. The desorption heating form is thermal regeneration, and the desorption temperature is 90° C.;

[0062] The lean amine liquid is cooled to 35° C., monoethanolamine, N-methyldiethanolamine and ethylenediamine are added to the lean amine liquid, the mass ratio of monoethanolamine: N-methyldiethanolamine: ethylenediamine is adjusted to 45:15:25, and the lean amine liquid is recycled in the absorption reaction, with a circulation volume of 100m 3 / h.

[0063] Example 3

[0064] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase, the method comprising:

[0065] Monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 55:25:35 to obtain an organic amine mixed liquid, and the organic amine mixed liquid is reversely contacted with a gas phase at 50° C. for absorption, and the absorption liquid-to-gas ratio is 5:1 to obtain a purified gas phase and a rich amine liquid at a temperature of 50° C.;

[0066] The rich amine liquid is heated to 80° C. and then desorbed for 5 minutes to obtain desorbed gas and lean amine liquid. The desorption heating method is thermal regeneration, and the desorption temperature is 95° C.;

[0067] The lean amine liquid is cooled to 50° C., monoethanolamine, N-methyldiethanolamine and ethylenediamine are added to the lean amine liquid, and the mass ratio of monoethanolamine: N-methyldiethanolamine: ethylenediamine is adjusted to 55:25:35, and the lean amine liquid is recycled in the absorption reaction, with a circulation volume of 50m 3 / h.

[0068] Example 4

[0069] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except that monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 40:10:20, the rest is the same as Embodiment 1.

[0070] Example 5

[0071] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except that monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 60:10:40, the rest is the same as Embodiment 1.

[0072] Example 6

[0073] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except that monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 70:5:15, the rest is the same as Embodiment 1.

[0074] Example 7

[0075] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in a gas phase. The only difference from Embodiment 1 is that, except that monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 30:40:10, the rest is the same as Embodiment 1.

[0076] Example 8

[0077] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except that the organic amine mixture is in reverse contact with the gas phase at 60° C. for absorption, the rest is the same as Embodiment 1.

[0078] Example 9

[0079] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except that the organic amine mixture is in reverse contact with the gas phase at 20° C. for absorption, the rest is the same as Embodiment 1.

[0080] Example 10

[0081] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except for the absorption liquid-to-gas ratio of 10:1, the rest is the same as Embodiment 1.

[0082] Embodiment 11

[0083] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Embodiment 1 is that, except for the liquid-to-gas ratio of absorption being 3:1, the rest is the same as Embodiment 1.

[0084] Example 12

[0085] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The difference from the embodiment 1 is that the desorption temperature is 100° C., and the rest is the same as the embodiment 1.

[0086] Example 13

[0087] This embodiment provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from the embodiment 1 is that the desorption temperature is 80° C., and the rest is the same as the embodiment 1.

[0088] Comparative Example 1

[0089] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Example 1 is that, except that N-methyldiethanolamine is replaced by N-ethyldiethanolamine, the rest is the same as Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, which is the same as Example 1 except that monoethanolamine is replaced by isopropanolamine.

[0092] Comparative Example 3

[0093] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Example 1 is that ethylenediamine is replaced by propylenediamine, and the rest is the same as Example 1.

[0094] Comparative Example 4

[0095] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Example 1 is that, except that monoethanolamine and N-methyldiethanolamine are mixed in a mass ratio of 50:20 to obtain an organic amine mixed solution, the rest is the same as Example 1.

[0096] Comparative Example 5

[0097] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Example 1 is that, in addition to mixing N-methyldiethanolamine and ethylenediamine in a mass ratio of 20:30 to obtain an organic amine mixed solution, the rest is the same as Example 1.

[0098] Comparative Example 6

[0099] This comparative example provides a method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase. The only difference from Example 1 is that, except that monoethanolamine and ethylenediamine are mixed in a mass ratio of 50:30 to obtain an organic amine mixed solution, the rest is the same as Example 1.

[0100] The contents of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the coke oven gas and the purified gas phase after absorption were detected by gas chromatography, and the removal rate = (inlet concentration - outlet concentration) / inlet concentration.

[0101] The contents of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase before and after absorption were detected, and their removal rates were obtained according to the above calculation formula. The detection results are shown in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] The test results show that:

[0106] (1) It can be seen from Examples 1 to 5 that the present invention can absorb hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase by using an organic amine mixed liquid, and can efficiently absorb hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device, so that the removal rate of hydrogen sulfide reaches more than 95%, the removal rate of carbon dioxide reaches more than 90%, and the removal rate of carbonyl sulfide reaches more than 95%, and the concentration of hydrogen sulfide in the purified gas phase is less than 0.2 g / m 3 , the concentration of carbon dioxide is less than 0.3%, and the concentration of carbonyl sulfide is less than 10 mg / m 3 .

[0107] (2) Combining Example 1 and Examples 6-7, it can be seen that in Example 1, monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 50:20:30 to obtain an organic amine mixed liquid, which can remove 99% of hydrogen sulfide, 95% of carbon dioxide and 99% of carbonyl sulfide after reverse contact and absorption with the gas phase; while in Example 6, monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 70:5:15 to obtain an organic amine mixed liquid, which can remove 90% of hydrogen sulfide, carbon dioxide and carbonyl sulfide after reverse contact and absorption with the gas phase; in Example 7, monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of 30:4 The organic amine mixed liquid is mixed at a ratio of 0:10, and after reverse contact and absorption with the gas phase, the removal rate of hydrogen sulfide, the removal rate of carbon dioxide and the removal rate of carbonyl sulfide are 90%, 88% and 92%, respectively. This shows that the present invention can ensure the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device by limiting the mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine to (40-60):(10-30):(20-40). If the mass ratio is too small, the absorption rate of CO2 will be too low, and the efficient removal of CO2 cannot be achieved. If the mass ratio is too large, the steric hindrance is large, resulting in low regeneration efficiency, further reducing the removal efficiency of the recycled lean amine liquid in the absorption process.

[0108] (3) Combining Example 1 and Examples 8-9, it can be seen that in Example 1, the temperature of the gas phase during the absorption process is 40°C, and after the gas phase is in reverse contact with the organic amine mixed solution for absorption, the removal rate of hydrogen sulfide is 99%, the removal rate of carbon dioxide is 95%, and the removal rate of carbonyl sulfide is 99%; while in Example 8, the temperature of the gas phase during the absorption process is 60°C, and after the gas phase is in reverse contact with the organic amine mixed solution for absorption, the removal rate of hydrogen sulfide is 88%, the removal rate of carbonyl sulfide is 88%, and the removal rate of carbonyl sulfide is 90%; in Example 9, the temperature of the gas phase during the absorption process is 20°C, and after the gas phase is in reverse contact with the organic amine mixed solution for absorption, the removal rate of hydrogen sulfide is 88%, the removal rate of carbonyl sulfide is 90%. After the mixed liquid is subjected to reverse contact absorption, the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide can be 85%, 90% and 90%, respectively. This indicates that the present invention can ensure the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device by controlling the temperature of the gas phase to 35-50° C. during the absorption process. If the temperature is too high, the technical energy consumption will increase and energy will be wasted. At the same time, the chemical balance between the organic amine mixed liquid and the gas phase will be destroyed, thereby reducing the absorption efficiency. If the temperature is too low, the absorption rate will decrease, thereby reducing the removal efficiency.

[0109] (4) It can be seen from Example 1 and Examples 10-11 that the liquid-to-gas ratio in the absorption process of Example 1 is 6:1, and after absorption, the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide can reach 99%, 95% and 99% respectively; while the liquid-to-gas ratio in the absorption process of Example 10 is 10:1, and after absorption, the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide can reach 90%, 85% and 85% respectively; the liquid-to-gas ratio in the absorption process of Example 11 is 3:1, and after absorption, the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide can reach 85%, 85% and 85% respectively. It can be seen that the present invention can ensure the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide in the same absorption device by controlling the liquid-to-gas ratio in the absorption process to (5-8):1. If the liquid-to-gas ratio in the absorption process is less than 5:1, the removal efficiency will be reduced. If the liquid-to-gas ratio in the absorption process is greater than 8:1, the tower will be flooded, causing the resistance of the absorption tower to increase sharply, and finally resulting in a reduction in the absorption efficiency.

[0110] (5) It can be seen from Example 1 and Examples 12-13 that the desorption operation temperature of Example 1 is 92° C., and the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide reach 99%, 95% and 99% respectively; while the desorption operation temperature of Example 12 is 100° C., and the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide are 85%, 88% and 84% respectively; and the desorption operation temperature of Example 13 is 80° C., and the removal rates of hydrogen sulfide, carbon dioxide and carbonyl sulfide are 85%, 82% and 85% respectively. It can be seen that when desorbing the rich amine solution, if the temperature is too low, the regeneration will be incomplete, thereby reducing the removal efficiency of the recycled lean amine solution in the absorption process; if the temperature is too high, the organic amine will decompose, which will also reduce the absorption efficiency.

[0111] (6) From Example 1 and Comparative Examples 1-3, it can be seen that the organic amine mixed solution in Comparative Example 1 is obtained by mixing monoethanolamine, N-ethyldiethanolamine and ethylenediamine in a mass ratio of 50:20:30, and its hydrogen sulfide removal rate is 70%, carbon dioxide removal rate is 75%, and carbonyl sulfide removal rate is 80%. The organic amine mixed solution in Comparative Example 2 is obtained by mixing isopropanolamine, N-methyldiethanolamine and ethylenediamine in a mass ratio of 50:20:30, and its hydrogen sulfide removal rate is 70%, carbon dioxide removal rate is 75%, and carbonyl sulfide removal rate is 80%. The removal rate of carbon oxide is 70%, and the removal rate of carbonyl sulfide is 75%. The organic amine mixed liquid in Comparative Example 3 is obtained by mixing monoethanolamine, N-methyldiethanolamine and propylenediamine in a mass ratio of 50:20:30, and its hydrogen sulfide removal rate is 67%, carbon dioxide removal rate is 65%, and carbonyl sulfide removal rate is 70%. It can be seen that in the structure of organic amine, nitrogen and hydroxyl groups are hydrophilic, and the carbon chain is hydrophobic. The longer the carbon chain, the less soluble the organic amine is in water. Therefore, an increase in the carbon chain length will reduce the absorption efficiency.

[0112] (7) It can be seen from Example 1 and Comparative Examples 4-6 that the organic amine solution of Comparative Example 4 does not contain ethylenediamine, and its hydrogen sulfide removal rate is 60%, carbon dioxide removal rate is 60%, and carbonyl sulfide removal rate is 75%. The organic amine solution of Comparative Example 5 does not contain monoethanolamine, and its hydrogen sulfide removal rate is 60%, carbon dioxide removal rate is 70%, and carbonyl sulfide removal rate is 70%. The organic amine solution of Comparative Example 6 does not contain N-methyldiethanolamine, and its hydrogen sulfide removal rate is 70%, carbon dioxide removal rate is 70%, and carbonyl sulfide removal rate is 75%. The removal rate of carbonyl sulfide is 60%, and the removal rate of monoethanolamine is 60%. It can be seen that monoethanolamine has a fast absorption rate and a large absorption capacity, and is the main absorbent; although the addition of ethylenediamine cannot increase the absorption rate, it can increase the absorption capacity, and the steric hindrance caused by the connection between the amino group and the secondary carbon makes it easier for carbamate to decompose; N-methyldiethanolamine is a tertiary alcohol amine, which plays a role similar to a catalyst in the reaction process, that is, the hydrogen bond formed between the free amine and water enhances the activity of the reaction between water and CO2, thereby promoting the hydration of CO2. That is, monoethanolamine, N-methyldiethanolamine and ethylenediamine cooperate with each other to simultaneously remove hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, so that the efficient removal of hydrogen sulfide, carbon dioxide and carbonyl sulfide can be completed in a single absorption device.

[0113] In summary, the present invention can simultaneously remove hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase in the same absorption process by selecting a specific organic amine mixed liquid. Only a single absorption device is required, which can reduce the floor space and promote the possibility of promoting the process in the existing coke oven gas purification facilities. It has good economic advantages. At the same time, the rich amine liquid after absorption can be desorbed and recycled, which can reduce the generation of wastewater and waste, and is in line with the current trend of waste-free pollution control.

[0114] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for simultaneously removing hydrogen sulfide, carbon dioxide and carbonyl sulfide in the gas phase, characterized in that: The method comprises: bringing the gas phase into reverse contact with the organic amine mixed liquid for absorption to obtain a purified gas phase and an amine-rich liquid; Wherein, the organic amine mixture includes monoethanolamine, N-methyldiethanolamine and ethylenediamine.

2. The method according to claim 1, characterized in that The mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine is (40-60):(10-30):(20-40).

3. The method according to claim 2, characterized in that The mass ratio of monoethanolamine, N-methyldiethanolamine and ethylenediamine is (45-55):(15-25):(25-35).

4. The method according to any one of claims 1 to 3, characterized in that: The temperature of the gas phase during the absorption is 35-50°C; Preferably, the liquid-to-gas ratio of the absorption is (5-8):

1.

5. The method according to any one of claims 1 to 4, characterized in that: The temperature of the rich amine solution is 35-50°C; Preferably, the temperature of the heated rich amine solution is 60-80°C.

6. The method according to any one of claims 1 to 5, characterized in that: The method further comprises: heating the rich amine liquid and performing desorption to obtain a desorbed gas phase and a lean amine liquid; Cooling the lean amine solution and recycling it in the absorption reaction; Preferably, the desorption heating form includes hot steam heating or hot nitrogen; Preferably, the desorption temperature is 90-95°C.

7. The method according to claim 6, characterized in that The desorption process of the desorption includes thermal regeneration; Preferably, the desorption time is 5-10 min.

8. The method according to claim 6 or 7, characterized in that: The temperature of the lean amine solution after cooling is 35-50°C.

9. The method according to any one of claims 6 to 8, characterized in that: The circulation volume of the lean amine solution is 50-100m 3 / h; Preferably, before the lean amine liquid is circulated, any one of monoethanolamine, N-methyldiethanolamine or ethylenediamine or a combination of at least two thereof is added to the lean amine liquid, and the mass ratio of monoethanolamine:N-methyldiethanolamine:ethylenediamine is adjusted to (40-60):(10-30):(20-40).

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises: monoethanolamine, N-methyldiethanolamine and ethylenediamine are mixed in a mass ratio of (40-60):(10-30):(20-40) to obtain an organic amine mixed liquid, the organic amine mixed liquid is reversely contacted with a gas phase at 35-50° C. to perform absorption, the liquid-to-gas ratio of the absorption is (5-8):1, and a purified gas phase and a rich amine liquid at a temperature of 35-50° C. are obtained; The rich amine liquid is heated to 60-80° C. and then desorbed to obtain desorbed gas and lean amine liquid, wherein the desorption temperature is 90-95° C.; The lean amine liquid is cooled to 35-50° C., any one of monoethanolamine, N-methyldiethanolamine or ethylenediamine or a combination of at least two thereof is added to the lean amine liquid, the mass ratio of monoethanolamine:N-methyldiethanolamine:ethylenediamine is adjusted to (40-60):(10-30):(20-40), and then the lean amine liquid is recycled in the absorption reaction.

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