Method for treating sulphur-containing exhaust gases and device thereof

Abstract

A method for treating sulfur-containing exhaust gases is provided, comprising the following steps: step i): mixing the sulfur-containing exhaust gases, air, and a hydrocarbon fuel, and controlling a reaction between the air and the hydrocarbon fuel therein, to obtain a procedure gas stream comprising the sulfur-containing exhaust gases, hydrogen, and carbon oxides; step ii): controlling a hydrogenation reaction between the hydrogen contained in the procedure gas stream and a sulfur-containing substance in the sulfur-containing exhaust gases, to obtain hydrogenated tail gases containing hydrogen sulfide; and step iii): absorbing the hydrogen sulfide contained in the hydrogenated tail gases with an absorbing agent to obtain purified tail gases.

Claims

1. A method for treating a sulfur-containing exhaust gas, comprising the following steps: step i): introducing a mixture of steam, the sulfur-containing gas, air, and a hydrocarbon fuel into an online heating furnace, and controlling a reaction between air and the hydrocarbon fuel therein to obtain a procedure gas stream containing a sulfur-containing substance, hydrogen, and carbon oxides, wherein the procedure gas stream is heated by heat released in a reaction between air and the hydrocarbon fuel, wherein the sulfur-containing exhaust gas is a Claus tail gas released from a tail gas purification unit, an exhaust gas from degassing of a liquid sulfur by bubbling air through the liquid sulfur, or a mixture thereof; step ii): controlling a hydrogenation reaction between hydrogen contained in the procedure gas stream and the sulfur-containing substance to obtain a hydrogenated tail gas containing hydrogen sulfide; and step iii) absorbing hydrogen sulfide contained in the hydrogenated tail gases with an absorbing agent to obtain a purified tail gas and an absorbing agent rich in hydrogen sulfide.

2. The method according to claim 1, further comprising incinerating and then discharging the purified tail pas.

3. The method according to claim 1, wherein the hydrocarbon fuel is a methane-containing gas.

4. The method according to claim 1, wherein the sulfur-containing exhaust gas is mixed with air before entering the online heating furnace.

5. The method according to claim 1, wherein a pressure of the steam ranges from 0.03 to 0.1 MPa, the steam is mixed with the sulfur-containing gas, and the mixture of the steam and the sulfur-containing gas passes through a steam ejector.

6. The method according to claim 1, wherein the procedure gas stream is heated to a temperature ranging from 200 to 300 C.

7. The method according to claim 1, wherein the sulfur-containing substance in the procedure gas stream is converted into hydrogen sulfide in a hydrogenator under the function of a hydrogenation catalyst.

8. The method according to claim 1, wherein the absorbing agent is a desulphurizer.

9. The method according to claim 1, wherein in step iii), the hydrogenated tail gas containing hydrogen sulfide is quenched in a quench tower to a temperature ranging from 25 to 42 C., before entering an absorbing tower filled with the absorbing agent, wherein the hydrogen sulfide is absorbed by the absorbing agent.

10. The method according to claim 1, wherein the absorbing agent rich in hydrogen sulfide is fed into an absorbent regeneration tower for regeneration, producing an acid gas and a regenerated absorbing agent, wherein the acid gas is fed into the online heating furnace and the regenerated absorbing agent is recycled to the absorbing tower.

11. The method according to claim 3, wherein the hydrocarbon fuel is natural gas.

12. The method according to claim 8, wherein the absorbing agent is an amine-containing liquid.

13. The method according to claim 8, wherein the absorbing agent is N-methyldiethanolamine.

14. The method according to claim 7, wherein the hydrogenation catalyst is catalyst LSH-03.

15. The method according to claim 2, wherein the pressure of steam ranges from or 0.5 to 0.1 MPa.

16. The method according to claim 9, wherein in step iii), the hydrogenated tail gas containing hydrogen sulfide is quenched in a quench tower to a temperature ranging from 30 to 38 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a flow chart according to an embodiment of the present disclosure; and

(2) FIG. 2 shows a flow chart according to another embodiment of the present disclosure.

(3) In the present disclosure, the same materials, units, or components are indicated by the same reference signs.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, group of elements, components, and/or groups thereof.

(5) Language such as including, comprising, having, containing, or involving, and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, as well as equivalents, and additional subject matter not recited. Further, whenever a composition, a group of elements, process or method steps, or any other expression is preceded by the transitional phrase comprising, including, or containing, it is understood that it is also contemplated herein the same composition, group of elements, process or method steps or any other expression with transitional phrases consisting essentially of, consisting of, or selected from the group of consisting of, preceding the recitation of the composition, the group of elements, process or method steps or any other expression.

(6) The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims, if applicable, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the present disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiments described herein were chosen and described in order to best explain the principles of the present disclosure and the practical application, and to enable others of ordinary skill in the art to understand the present disclosure for various embodiments with various modifications as are suited to the particular use contemplated. Accordingly, while the present disclosure has been described in terms of embodiments, those of skill in the art will recognize that the present disclosure can be practiced with modifications and in the spirit and scope of the appended claims.

(7) Reference will now be made in detail to certain disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that they are not intended to limit the disclosed subject matter to those claims. On the contrary, the disclosed subject matter is intended to cover all alternatives, modifications, and equivalents, which can be included within the scope of the presently disclosed subject matter as defined by the claims.

(8) Sulfur-Containing Exhaust Gases

(9) The method of the present disclosure can be used for treating any sulfur-containing exhaust gases, and particularly suitable for treating Claus tail gases released from a tail gas purification unit of a sulfur recovery plant, and/or exhaust gases released from a sulfur plant during liquid sulfur degassing.

(10) Specifically, the tail gases released from a tail gas purification unit of a sulfur recovery plant, i.e., Claus tail gases, are generated after acid gasses from a Claus process for reduction, absorption and recovery of sulfur pass through a reacting furnace, a primary-stage sulfur cooler, a primary-stage reactor, a secondary-stage sulfur cooler, a secondary-stage reactor, and a third-stage sulfur cooler. The Claus tail gases comprise 0-5% by volume of H.sub.2S, 0-2% by volume of SO.sub.2, 0-0.2% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances, preferably 0-3% by volume of H.sub.2S, 0-1% by volume of SO.sub.2, 0-0.1% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances.

(11) Specifically, the exhaust gases generated during liquid sulfur degassing refer to sulfur-containing exhaust gases generated after a liquid sulfur degassing procedure is performed on liquid sulfur produced by a sulfur plant, through air bubble degassing or stripping tower degassing, wherein the liquid sulfur degassing procedure employs air as a gas source. The exhaust gasses generated during the liquid sulfur degassing comprise air, sulfur vapor, hydrogen sulfide, sulfur dioxide, organic sulfur, etc. In the present disclosure, steam power is preferably used for introducing the exhaust gases generated during liquid sulfur degassing into the online heating furnace, wherein the pressure of the steam ranges from 0.03 to 0.1 MPa, preferably 0.05 to 0.1 MPa, and the amount of steam used ranges from 0.1 to 2 t/h, preferably 0.3 to 1.0 t/h.

(12) The exhaust gases generated during liquid sulfur degassing are mixed with air in the online heating furnace before hydrogenation. That is, the exhaust gases generated during liquid sulfur degassing are introduced into the online heating furnace in the form of air. As a result, the amount of air supplied into the online heating furnace can be reduced, wherein oxygen is consumed through reactions with the hydrocarbon fuel as indicated above in formulae (1) and (2).

(13) Online Heating Furnace

(14) The online heating furnace of the present disclosure can be any online heating furnace used in the art.

(15) Hydrogenator

(16) The hydrogenator of the present disclosure can be any hydrogenator used in the art.

(17) Hydrogenation Catalyst

(18) The hydrogenation catalyst used in the present disclosure refers to high activity catalyst LSH-03, which is developed by Research Institute of Qilu Branch Co., SINOPEC, and disclosed in CN 201010269123.7, the entirety of which is incorporated herein by reference.

Example 1

(19) The procedure is shown in FIG. 1. In this example, the sulfur-containing exhaust gases included Claus tail gases 3 released from a tail gas purification unit of a sulfur recovery plant, and exhaust gases 23 generated during liquid sulfur degassing. The procedure of this example specifically included the following steps.

(20) In step i) of this procedure, Claus tail gases 3 released from a tail gas purification unit of a sulfur recovery plant and exhaust gasses 23 generated during liquid sulfur degassing were both fed into an online heating furnace 4. The liquid sulfur degassing was performed through air bubble degassing or stripping tower degassing, and a steam 20 was used for feeding the exhaust gasses 23 generated during liquid sulfur degassing into the online heating furnace 4. Sulfur-containing exhaust gases, including the Claus tail gases 3 released from the tail gas purification unit and the exhaust gasses 23 generated during liquid sulfur degassing, were mixed with an air 1 and a hydrocarbon fuel 2 in the online heating furnace 4, wherein the air 1 and the hydrocarbon fuel 2 reacted with each other to generate carbon oxides and hydrogen. As such, a procedure gas stream comprising sulfur-containing exhaust gases, hydrogen, and carbon oxides were obtained, and was heated to a temperature in the range from 200 to 300 C. in the online heating furnace 4.

(21) In step ii), the procedure gas stream was fed into a hydrogenator 5, wherein sulfur-containing compounds were converted into hydrogen sulfide under the function of a hydrogenation catalyst. Thus, hydrogenated tail gases containing hydrogen sulfide were obtained.

(22) In step iii), the hydrogenated tail gases containing hydrogen sulfide were quenched to 38 C. in a quench tower 7, and then entered an absorbing tower 10. Absorbing agent N-methyldiethanolamine filled in the absorbing tower absorbed hydrogen sulfide contained in the hydrogenated tail gases, to generate purified tail gases 14 and an absorbing agent 11 absorbed with hydrogen sulfide. The purified tail gases 14 were introduced into an incinerator 15 and incinerated therein, before being discharged therefrom, while the absorbing agent 11 absorbed with hydrogen sulfide entered a regeneration tower for regeneration. A regenerated absorbing agent 13 was obtained and returned to the absorbing tower 10, while a regenerated acid gas entered the sulfur recovery procedure.

(23) The Claus tail gases 3 released from the tail gas purification unit of the sulfur recovery plant comprised 2% by volume of H.sub.2S, 1% by volume of SO.sub.2, 0.05% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances.

(24) The liquid sulfur degassing was performed through air bubble degassing or stripping tower degassing, at a flow of 0.05 kg of air per kg of liquid sulfur. The steam 20 was used for introducing exhaust gases generated during liquid sulfur degassing into the online heating furnace 4, wherein the steam was at a pressure of 0.1 MPa and a flow of 0.5 t/h.

(25) High activity catalyst LSH-03 developed by Research Institute of Qilu Branch Co., SINOPEC was used in this example.

(26) The concentrations of SO.sub.2 in the flue gases emitted from the sulfur plant of this example were listed in Table 1.

Example 2

(27) The procedure steps of Example 1 were used in this example, and the Claus tail gases 3 from the tail gas purification unit of the sulfur recovery plant comprised 1% by volume of H.sub.2S, 0.5% by volume of SO.sub.2, 0.02% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances.

(28) The liquid sulfur degassing was performed through air bubble degassing or stripping tower degassing, at a flow of 0.06 kg of air per kg of liquid sulfur. The steam 20 at a pressure of 0.3 MPa and a flow of 0.5 t/h was used for introducing exhaust gases generated during liquid sulfur degassing into the online heating furnace 4.

(29) The concentrations of SO.sub.2 in the flue gases emitted from the sulfur plant of this example were listed in Table 1.

Example 3

(30) The procedure steps of Example 1 were used, and the Claus tail gases 3 released from the tail gas purification unit of the sulfur recovery plant comprised 2% by volume of H.sub.2S, 1.0% by volume of SO.sub.2, 0.05% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances.

(31) The liquid sulfur degassing was performed through air bubble degassing or stripping tower degassing, at a flow of 0.1 kg of the air 1 per kg of liquid sulfur. The steam 20 at a pressure of 0.3 MPa and a flow of 1.0 t/h was used for introducing the exhaust gases generated during liquid sulfur degassing into the online heating furnace 4.

(32) The hydrogenated tail gases containing hydrogen sulfide were quenched to 40 C. in the quench tower 7.

(33) The concentrations of SO.sub.2 in the flue gases emitted from the sulfur plant of this example were listed in Table 1.

Example 4

(34) According to the procedure steps as shown in FIG. 2, exhaust gases generated during sulfur degassing were directly introduced into the incinerator 15 for incineration. The tail gases released from the sulfur recovery plant were treated in the same way as explained in Example 1.

(35) The Claus tail gases 3 released from the tail gas purification unit of the sulfur recovery plant comprised 2% by volume of H.sub.2S, 1.0% by volume of SO.sub.2, 0.05% by volume of COS, and sulfur vapor, saturated water vapor, and nitrogen as balances.

(36) The liquid sulfur degassing was performed through air bubble degassing or stripping tower degassing, at a flow of 0.1 kg of the air 1 per kg of liquid sulfur.

(37) The steam 20 at a pressure of 0.3 MPa and a flow of 1.0 t/h was used for introducing the exhaust gases generated during liquid sulfur degassing into the online heating furnace 4.

(38) The Claus tail gases 3, after being heated to a temperature in the range from 200 to 300 C. in the online heating furnace 4, entered the hydrogenator 5, wherein sulfur-containing compounds were converted into hydrogen sulfide under the function of a hydrogenation catalyst. The hydrogenated tail gases containing hydrogen sulfide were quenched to 40 C. in the quench tower 7, and then entered the absorbing tower 10 filled with amine liquor, wherein the amine liquor absorbed hydrogen sulfide contained in the hydrogenated tail gases, to generate purified tail gases 14. Afterwards, the purified tail gases 14 were mixed with the exhaust gases generated during liquid sulfur degassing. The resulting mixture thereof was introduced into the incinerator 15 and discharged therefrom after incineration.

(39) The concentrations of SO.sub.2 in the flue gases emitted from the sulfur plant of this example were listed in Table 1.

(40) The amine liquor absorbed with hydrogen sulfide (rich amine solution) entered the regeneration tower 12, to produce a regenerated acid gas, which was mixed with acid gases in the reaction furnace, and returned to a thermal reaction section for further recovery of the element of sulfur.

(41) The exhaust gasses generated during liquid sulfur degassing, comprising air, sulfur vapor, hydrogen sulfide, organic sulfur, and the like, were heated to a temperature in the range from 500 to 800 C. in the incinerator, wherein the sulfur vapor, the hydrogen sulfide, the organic sulfur, and the like were converted into SO.sub.2.

(42) In table 1, numbers 1-9 indicate nine experiments performed in similar manners with nine samples.

(43) TABLE-US-00001 TABLE 1 Concentrations of SO.sub.2 in the flue gases emitted from the sulfur plant (mg/m.sup.3) Number of sample Example 1 Example 2 Example 3 Example 4 1 202 180 280 450 2 186 220 265 389 3 150 260 270 420 4 201 201 220 386 5 220 198 230 398 6 230 169 198 400 7 280 256 200 450 8 286 232 210 520 9 270 200 256 480

(44) Table 1 indicates that the concentration of SO.sub.2 in the flue gases emitted from the sulfur plant of the present disclosure (Examples 1, 2, and 3) is lower than 300 mg/m.sup.3, which is 100-300 mg/m.sup.3 lower than the concentration of SO.sub.2 in the flue gases generated in the procedure steps of Example 4. As can be concluded, the present disclosure excels in treating exhaust gases generated during liquid sulfur degassing, and the requirements of the environment protection laws and regulations to be implemented can be satisfied though the method of the present disclosure.

Comparative Example 1

(45) The procedure steps of Example 4 were used. The hydrogenator 5 was filled with ordinary hydrogenation catalyst LS-951, which was developed by Research Institute of Qilu Branch Co., SINOPEC, and disclosed in CN 200310105748.X, the entirety of which is incorporated herein by reference, for hydrogenation of Claus tail gases 3. The exhaust gases generated during liquid sulfur degassing were heated to a required temperature in a heater. The test results of Example 1 and Comparative Example 1 using different hydrogenation catalysts and different procedure steps were shown in Table 2.

(46) TABLE-US-00002 TABLE 2 Test results of different hydrogenation catalysts Inlet temperature ( C.) Example 1 Comparative Example 1 220 Conversion of 100 70 hydrogenation, % Conversion of 100 51 hydrolysis, % Phenomenon The sulfur plant Sulfur accumulated in worked properly. the quench tower. 240 Conversion of 100 95 hydrogenation, % Conversion of 100 80 hydrolysis, % Phenomenon The sulfur plant Sulfur accumulated in worked properly. the quench tower. 260 Conversion of 100 100 hydrogenation, % Conversion of 100 95 hydrolysis, % Phenomenon The sulfur plant Sulfur accumulated in worked properly. the quench tower. 280 Conversion of 100 100 hydrogenation, % Conversion of 100 100 hydrolysis, % Phenomenon The sulfur plant The sulfur plant worked properly. worked properly.

(47) The results in Table 2 show that, high activity catalyst LSH-03 developed by Research Institute of Qilu Branch Co., SINOPEC, was used in the hydrogenator reactor 5 in Example 1, such that the inlet temperature of the hydrogenator 5 was lowered down to 220 C., and the sulfur plant worked properly. The exhaust gases generated during liquid sulfur degassing could be directly mixed with the Claus tail gases 3 without having to be heated. In Comparative Example 1, traditional hydrogenation catalyst LS-951 developed by Research Institute of Qilu Branch Co., SINOPEC was used for hydrogenation of Claus tail gases 3. This rendered it necessary to use a gas heater to heat the exhaust gases generated during liquid sulfur degassing to about 280 C., so as to ensure a 100% of hydrogenation conversion and a 100% of hydrolysis conversion. A temperature lower than 260 C. cannot satisfy the requirements for the hydrogenation conversion or the hydrolysis conversion. In addition, the quench tower 7 would be frequently blocked, which is a suggestion of incomplete hydrogenation of sulfur vapor carried in the exhaust gases generated during liquid sulfur degassing, and occurrence of the phenomenon of sulfur penetration. Therefore, high activity catalyst LSH-03 can be used to bring about better effects.

(48) As will be appreciated by one skilled in the art, the foregoing functions and/or process may be embodied as a system, method or computer program product. For example, the functions and/or process may be implemented as computer-executable program instructions recorded in a computer-readable storage device that, when retrieved and executed by a computer processor, controls the computing system to perform the functions and/or process of embodiments described herein. In one embodiment, the computer system can include one or more central processing units, computer memories (e.g., read-only memory, random access memory), and data storage devices (e.g., a hard disk drive). The computer-executable instructions can be encoded using any suitable computer programming language (e.g., C++, JAVA, etc.). Accordingly, aspects of the present disclosure may take the form of an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects.

(49) From the above description, it is clear that the present disclosure is well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the presently provided disclosure. While preferred embodiments have been described for purposes of this disclosure, it will be understood that changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the present disclosure.

LIST OF REFERENCE NUMBERS

(50) 1. air; 2. hydrocarbon fuel; 3. Claus tail gases; 4. online heating furnace; 5. hydrogenator; 6. steam generator; 7. quench tower; 8. circulating pump; 9. sewage; 10. absorbing tower; 11. absorbing agent absorbed with hydrogen sulfide; 12. regeneration tower; 13. regenerated absorbing agent; 14. purified tail gases; 15. incinerator; 16. chimney; 17. air blower; 18. flowmeter; 19. degassing tank; 20. steam; 21. stream ejector; 22. liquid sulfur tank; and 23. exhaust gases generated during liquid sulfur degassing.