JP2010052955A - Method for operating sulfur recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operating method of a sulfur recovery apparatus by which the quantity of atmospheric pollutant to be discharged to the air is sufficiently reduced while sufficiently reducing the remaining quantity of iron sulfide in a sulfur recovery apparatus when the operation of the sulfur recovery apparatus is stopped. <P>SOLUTION: The sulfur recovery apparatus 1 is provided with a reaction furnace 12 for combusting H<SB>2</SB>S to produce SO<SB>2</SB>, a sulfur recovery part 10 provided with a first reactor 14 for producing sulfur by the reaction of SO<SB>2</SB>with H<SB>2</SB>S, a second reactor 34 for hydrogenating SO<SB>2</SB>produced in the sulfur recovery part 10 and a gas absorption part 20 provided with an absorption column 38 for absorbing H<SB>2</SB>S produced by the hydrogenation in an absorption liquid. The operation method in the stoppage of the operation of the apparatus, comprises a step of combusting iron sulfide stuck on the inner part of the sulfur recovery part 10 while O<SB>2</SB>in the first reactor 14 is kept to 0-1 vol.% by supplying air and H<SB>2</SB>in an air/fuel ratio exceeding theoretical air/fuel ratio; and a step of reducing SO<SB>2</SB>produced in the preceding step in the second reactor 34 and absorbing H<SB>2</SB>S with the absorption liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for operating a sulfur recovery apparatus.

  In the refining of various petroleum products and petrochemical products, in order to improve product stability, odor, corrosiveness, etc., there is a step of removing sulfur components using an indirect desulfurization apparatus or a direct desulfurization apparatus. Usually, in a desulfurization apparatus, a sulfur component contained in heavy oil, heavy light oil, light light oil, kerosene, naphtha or the like is converted to hydrogen sulfide and removed using a catalyst in the presence of hydrogen gas. The produced hydrogen sulfide gas is usually converted into sulfur by a Claus reaction after being partially converted to sulfur dioxide in a sulfur recovery device.

  As a specific treatment method of hydrogen sulfide gas in the sulfur recovery device, a part of the hydrogen sulfide gas is burned to produce sulfur dioxide, and this sulfur dioxide and unburned hydrogen sulfide are subjected to a Claus reaction in the presence of a catalyst. The method of producing sulfur and water is adopted. In this way, the sulfur recovery device that performs the treatment of hydrogen sulfide gas normally combusts hydrogen sulfide, performs a Claus reaction, and recovers sulfur, and a surplus generated in the sulfur recovery unit. Sulfur dioxide is heated and reduced with hydrogen in the presence of a catalyst to form hydrogen sulfide. The gas absorption part absorbs the hydrogen sulfide with an absorption liquid and the combustion part burns off-gas from which hydrogen sulfide has been removed.

  FIG. 2 is a schematic configuration diagram for explaining a conventional operation method of the sulfur recovery apparatus. The sulfur recovery device 3 includes a sulfur recovery unit 100, a gas absorption unit 200, and a combustion unit 300. In a normal operation state, hydrogen sulfide gas (acid gas) and air are supplied to the reaction furnace 112 at a predetermined ratio, and part of the hydrogen sulfide gas burns to generate sulfur oxide (sulfur dioxide). The produced sulfur dioxide and unburned hydrogen sulfide gas are introduced into the first reactor 114 having a Claus catalyst through the pipe L102. In the first reactor 114, the Claus reaction proceeds to generate sulfur from hydrogen sulfide and sulfur dioxide. The generated sulfur is introduced into the condenser 116 through the pipe L104 together with the unreacted gas containing sulfur dioxide and hydrogen sulfide, and is recovered in a liquid state from the condenser 116.

  On the other hand, unreacted gas (including hydrogen sulfide and sulfur oxide) that has not reacted in the first reactor 114 is introduced into the heater 132 of the gas absorption unit 200 through the pipe L106 and the valve V104. In the steady operation of the sulfur recovery device 3, the valve V102 is closed to prevent the unreacted gas from being combusted in the combustor 139 and releasing air pollutants. The unreacted gas is heated to a predetermined temperature together with the hydrogen gas introduced by the heater 132, and is introduced into the second reactor 134 having the hydrogenation catalyst through the pipe L110. In the second reactor 134, sulfur oxide contained in the unreacted gas is hydrogenated by the action of the hydrogenation catalyst to generate hydrogen sulfide and water. These hydrogen sulfide and water are introduced into the quencher 136 through the pipe L112 together with other by-product gases, and separated into a gas fraction containing hydrogen sulfide and water. The gas fraction separated by the quencher 136 is introduced into the gas absorption tower 138 through the pipe L114 and the pipe L116, and hydrogen sulfide contained in the gas fraction is absorbed by the absorbing liquid supplied through the pipe L124. The absorbing solution that has absorbed hydrogen sulfide is discharged through the pipe L126, and is separated from this absorbing solution by another device. The separated hydrogen sulfide is supplied again to the reaction furnace 112 of the sulfur recovery device 3 in some cases. On the other hand, off-gas (fuel gas) contained in the gas fraction is introduced into the combustor 139 through the pipe L122 and burned.

By the way, sulfur oxide gas (SO _x ) such as sulfur dioxide is known as an air pollutant and has high toxicity. Therefore, it is required to reduce the amount released to the atmosphere as much as possible. For this reason, it is required to reduce as much as possible the amount of sulfur oxide gas generated in the sulfur recovery device to the atmosphere.

However, when the amount of raw material hydrogen sulfide gas fluctuates and becomes excessive or insufficient, when the operation of the sulfur recovery device is stopped, or when the operation is started thereafter, the load on the sulfur recovery device fluctuates As a result, it becomes difficult to adjust the operation, and hydrogen sulfide gas that cannot be processed by the gas absorption unit must be burned in the combustor 139 via the pipe L108. In this case, sulfur oxide gas such as sulfur dioxide is temporarily discharged from the combustor into the atmosphere. As an operation method for suppressing the discharge of air pollutants during such load fluctuations, it has been proposed to inject a combustible gas into the apparatus (see, for example, Patent Document 1).
JP 10-265204 A

  The sulfur recovery device needs to periodically perform maintenance and repair by opening devices such as a heat exchanger and a heating furnace, and each time a stop operation and a start operation are required. Since each apparatus which comprises a sulfur collection | recovery apparatus contains iron, iron sulfide precipitates inside an apparatus by driving | operation. For this reason, when stopping the operation, it is necessary to perform so-called sulfur burning that burns and removes iron sulfide adhering to the inside of the sulfur recovery part of the sulfur recovery device in order to prevent ignition by iron sulfide before releasing each device. There is.

  However, during sulfur burning, there is a problem in that the amount of air pollutants such as sulfur oxide is increased. This is because the combustion gas generated when the iron sulfide of the sulfur recovery unit 100 is burned contains oxygen, so that the gas absorption unit 200 can handle the second catalyst for the hydrogenation reaction. This is because the combustion gas is directly burned in the combustor 139 of the combustion unit 300.

  For this reason, there is a need for a method of operating a sulfur recovery apparatus that can perform sulfur burning without increasing the amount of air pollutants discharged into the atmosphere during a shutdown operation of the sulfur recovery apparatus.

  The present invention has been made in view of such circumstances, and at the time of shutdown operation of the sulfur recovery device, the amount of air pollutants discharged to the atmosphere while sufficiently reducing the residual amount of iron sulfide in the sulfur recovery device An object of the present invention is to provide a method for operating a sulfur recovery apparatus that can sufficiently reduce the amount of sulfur.

  In order to achieve the above object, in the present invention, a reactor for combusting hydrogen sulfide to produce sulfur dioxide, and a first reactor having a first catalyst for producing sulfur by claus reaction of sulfur dioxide and hydrogen sulfide, And a second reactor having a second catalyst for producing hydrogen sulfide by hydrogenating sulfur dioxide produced in the sulfur collecting portion, and absorbing hydrogen sulfide produced in the second reactor An operation method of a sulfur recovery device comprising a gas absorption part comprising an absorption tower to be absorbed in a liquid, and when the operation of the sulfur recovery device is stopped, the reactor is combined with a fuel gas mainly containing hydrogen. By supplying air for burning fuel gas at an air-fuel ratio exceeding the stoichiometric air-fuel ratio, the iron sulfide adhering to the inside of the sulfur recovery unit is burned while maintaining the oxygen concentration in the first reactor at 0 to 1% by volume. Combustor A sulfur recovery device comprising: a hydrogenation reaction of sulfur dioxide generated by the combustion of iron sulfide in a second reactor of the gas absorption unit to generate hydrogen sulfide and absorb the hydrogen sulfide with an absorbing liquid Provide a method.

  In the operation method of the sulfur recovery apparatus of the present invention, when the operation of the sulfur recovery apparatus is stopped, the air supplied to the reaction furnace is supplied at a ratio exceeding the theoretical air-fuel ratio with respect to the fuel gas supplied to the reaction furnace. The oxygen concentration in the first reactor is adjusted to a range of 0 to 1% by volume. As a result, the oxygen concentration in the gas absorption part is kept sufficiently low, so that iron sulfide adhering to the inner wall surface of the sulfur recovery part gradually reacts with oxygen while sufficiently suppressing damage to the second catalyst due to oxygen. Can be eliminated sufficiently. Since hydrogen sulfide generated by the reaction between iron sulfide and oxygen is absorbed by the absorption liquid in the absorption tower of the gas absorption section, the amount of emission of air pollutants such as sulfur oxide can be sufficiently reduced.

  Further, in the present invention, before the combustion step, air for combusting the fuel gas together with the fuel gas containing hydrogen as a main component is supplied to the reaction furnace at an air-fuel ratio equal to or lower than the theoretical air-fuel ratio, and the first reactor is set to 230 ° C. or lower. It is preferable to have a gas purge step for lowering the temperature. In this gas purge step, hydrogen sulfide, sulfur oxide, and sulfur in the sulfur recovery unit system can be completely purged with combustion gas (hot inert gas) obtained by burning the fuel gas.

  In the above-described operation method of the sulfur recovery apparatus, compared with the conventional sulfur burning method, the temperature of the first reactor is decreased before the combustion process and the air-fuel ratio is decreased, thereby remaining in the sulfur recovery apparatus. It prevents sulfur from burning. This makes it possible to selectively burn only the iron sulfide in the sulfur recovery section in the combustion process, and to easily stop the sulfur recovery device.

  According to the operation method of the sulfur recovery apparatus of the present invention, when the sulfur recovery apparatus is stopped, the amount of atmospheric pollutants released to the atmosphere is sufficiently reduced while sufficiently reducing the residual amount of iron sulfide in the sulfur recovery apparatus. Can be reduced.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings as the case may be.

  FIG. 1 is a schematic configuration diagram of a sulfur recovery apparatus for explaining a preferred embodiment of the operation method of the present invention. The sulfur recovery device 1 includes a sulfur recovery unit 10, a gas absorption unit 20, and a combustion unit 30.

  In the steady operation of the sulfur recovery apparatus 1, hydrogen sulfide gas and air are supplied to the reaction furnace 12 of the sulfur recovery unit 10 at a predetermined ratio, and a part of the hydrogen sulfide gas burns to generate sulfur dioxide (described below). Formula (1)). The ratio of hydrogen sulfide gas and air supplied to the reaction furnace 12 is a ratio at which 1/3 of the total supply amount of hydrogen sulfide gas burns according to the following formula (1). By adjusting to this ratio, the Claus reaction represented by the following formula (2) can be efficiently advanced, and generation of unreacted hydrogen sulfide and sulfur dioxide can be sufficiently suppressed. Further, the amount of sulfur recovered in the sulfur recovery device 1 can be increased. Iron sulfide is generated inside the sulfur recovery unit 10 of the sulfur recovery apparatus 1 that performs such processing.

H ₂ S + 3 / 2O ₂ → SO ₂ + H ₂ O (1)
2H ₂ S + SO ₂ → 2H ₂ O + 3S (2)

  In the operation method of this embodiment, when the sulfur recovery apparatus 1 in a steady operation state is shut down, it is obtained by supplying air that burns the fuel gas together with the fuel gas mainly containing hydrogen to the reaction furnace 12. A gas purging process for purging hydrogen sulfide, sulfur oxide, and sulfur in the sulfur recovery unit system with a combustion gas (hot inert gas), and air for burning the fuel gas in the reaction furnace 12 together with a fuel gas mainly composed of hydrogen Is supplied at an air / fuel ratio exceeding the stoichiometric air / fuel ratio, while maintaining the oxygen concentration in the first reactor 14 in the range of 0 to 1% by volume, the iron sulfide present in the sulfur recovery unit 10 and the gas absorption unit 20 is reduced. It has a combustion process for burning, and an absorption process for reducing sulfur oxide generated in the combustion process to hydrogen sulfide by reducing it in the second reactor 34, and absorbing hydrogen sulfide with an absorbing liquid. Hereinafter, each step will be described in detail.

(Gas purge process)
In the gas purge step, the supply of hydrogen sulfide gas (acid gas) to the reaction furnace 12 is stopped, and the supply of fuel gas containing hydrogen as a main component to the reaction furnace 12 is started. In addition, it is preferable to perform gradually the operation for stopping the supply of hydrogen sulfide gas and the operation for starting the supply of fuel gas from the viewpoint of suppressing fluctuations in operation of the sulfur recovery apparatus 1. For example, it is preferable to prevent a rapid temperature fluctuation of the reaction furnace 12 by increasing the supply amount of the fuel gas so as to meet the decrease in the supply amount of the hydrogen sulfide gas.

  As the fuel gas containing hydrogen as a main component supplied to the reactor 12, for example, hydrogen gas generated from an ordinary hydrogen production apparatus may be used, or a reformed gas (hydrogen gas content produced from an ordinary hydrogen production apparatus) may be used. : About 80% by mass). The reformed gas contains a lower hydrocarbon gas such as methane gas or ethane gas as a subsidiary component in addition to the main component hydrogen gas. The content of hydrogen gas in the fuel gas is preferably 70% by mass or more, and more preferably 80% by mass or more.

  The reactor 12 is preferably supplied with fuel gas and air for burning the fuel gas at an air-fuel ratio equal to or lower than the stoichiometric air-fuel ratio, and more preferably at a stoichiometric air-fuel ratio. This makes it possible to smoothly burn the fuel gas and smoothly replace the combustion gas in the apparatus while preventing damage to the second catalyst due to an increase in the oxygen concentration in the sulfur recovery apparatus 1. In the present specification, “theoretical air / fuel ratio” refers to the mass ratio of air necessary for complete combustion of the fuel gas with respect to the fuel gas, and “the air / fuel ratio” refers to the mass ratio of air to the fuel gas. Say. The ratio of air to fuel gas in the gas purge step is preferably 80 to 110% by mass, and preferably 95 to 105% by mass based on the theoretical air-fuel ratio (100% by mass).

  The fuel gas supplied to the reaction furnace 12 is combusted by air supplied at a ratio of the stoichiometric air-fuel ratio to the fuel gas to generate combustion gas. The combustion gas generated in the reaction furnace 12 is introduced into the first reactor 14 filled with the Claus reaction catalyst through the pipe L2.

  The combustion gas that has passed through the first reactor 14 is introduced into the condenser 16 through the pipe L4. A normal heat exchanger can be used as the condenser 16. A refrigerant (for example, water) is supplied to the condenser 16, and the combustion gas can be cooled to a predetermined temperature.

  The combustion gas that has passed through the condenser 16 is introduced into the heater 32 provided on the upstream side of the gas absorption unit 20 through the pipe L6. In the gas purge process, the valve V4 is opened and the valve V2 is closed. A normal line heater can be used as the heater 32.

  The combustion gas that has passed through the second reactor 34 is introduced into the quencher 36 through the pipe L12. As the quencher 36, a normal tower or a vessel can be used. In the quencher 36, water generated by cooling the combustion gas can be separated and discharged.

  Part of the combustion gas that has passed through the quencher 36 is introduced into the gas absorption tower 38 via the pipes L14 and L16. Further, part of the combustion gas that has passed through the quencher 36 passes through the pipe L18, the blower 37, and the pipe L20 and is recycled to the heater 32. The combustion gas introduced into the gas absorption tower 38 is introduced into the combustor 39 through the pipe L22 and processed.

  Through the above gas purge process, the entire sulfur recovery device 1 is purged with combustion gas, and hydrogen sulfide, sulfur dioxide, and sulfur in the device are eliminated. Thereby, the operation of stopping the operation of the sulfur recovery apparatus 1 can be performed smoothly. Prior to the start of the combustion process, the first reactor 14 is preferably cooled to 230 ° C. or lower, more preferably 180 to 230 ° C. By cooling the reactor 14 to 230 ° C. or lower, sulfur combustion is suppressed in the combustion process described later, and iron sulfide can be burned more selectively. In addition, when the sulfur collection | recovery part 10 is cooled too much, it may become the temperature below a dew point and there exists a possibility that each apparatus which comprises the sulfur collection | recovery apparatus 1 may be damaged.

  When the temperature in the sulfur recovery apparatus 1 is cooled to 230 ° C. or lower by the gas purge process, the combustion process is performed.

(Combustion process)
In the combustion process, air for burning the fuel gas together with the fuel gas is supplied to the reaction furnace 12 at an air-fuel ratio exceeding the theoretical air-fuel ratio, and the fuel gas is combusted. Thereby, the oxygen concentration in the first reactor 14 arranged on the downstream side of the reaction furnace 12 is maintained in the range of 0 to 1% by volume, and the reaction of the following formula (3) proceeds, mainly the first reactor. 14 and the iron sulfide adhering to the inner wall of the condenser 16 are burned. In the combustion process, by maintaining the oxygen concentration in the first reactor 14 at 0 to 1% by volume or less, iron sulfide can be smoothly burned while sufficiently suppressing damage to the second catalyst for the hydrogenation reaction. it can.

2FeS + 7 / 2O ₂ → Fe ₂ O ₃ + 2SO ₂ (3)

  The ratio of air to fuel gas in the combustion process is preferably 101 to 110% by mass, more preferably 104 to 110% by mass, based on the theoretical air / fuel ratio (100% by mass). When the air ratio is less than 101% by mass, it tends to take a long time to complete the combustion of iron sulfide, and when it exceeds 110% by mass, the second catalyst for the hydrogenation reaction is sufficiently damaged. It tends to be difficult to suppress.

  The flow path of the combustion gas and oxygen is the same as the flow path of the combustion gas in the gas purge process. As a result, the entire inner wall of the sulfur recovery device 1 can be brought into contact with oxygen, and the iron sulfide adhering to the inner wall can be burned and removed in the entire sulfur recovery device 1.

  The oxygen concentration in the first reactor 14 is preferably 0.01 to 1.0% by volume, and more preferably 0.5 to 1.0% by volume. When the oxygen concentration is less than 0.01% by volume, the iron sulfide tends to require a long time for combustion removal and the iron sulfide tends to be insufficiently burned, and the oxygen concentration exceeds 1.0% by volume. In this case, the hydrogenation catalyst provided in the second reactor 34 tends to be damaged.

  In the combustion process, the first reactor 14 is preferably in a temperature range that exceeds the dew point and is 230 ° C. or less, and more preferably 180 to 220 ° C. When the temperature of the sulfur frequency unit 10 is equal to or lower than the dew point, each device constituting the sulfur recovery device 1 tends to be easily damaged. On the other hand, when the temperature of the first reactor 14 exceeds 230 ° C., sulfur tends to burn and generate a large amount of sulfur dioxide.

  A combustion process is complete | finished if combustion removal of the iron sulfide adhering to the inner wall of each apparatus which comprises the sulfur collection | recovery part 10 of the sulfur collection | recovery apparatus 1 is completed.

(Absorption process)
In the combustion process, the sulfur dioxide produced by the reaction of the above formula (3) is reacted with hydrogen in each apparatus such as the first reactor 14 and the condenser 16 in the combustion process to form hydrogen sulfide. In this step, hydrogen is absorbed by the absorption liquid in the gas absorption tower 38.

  Sulfur dioxide generated by the above formula (3) is introduced from the sulfur recovery unit 10 through the pipe L6 and the valve V4 to the heater 32 and heated to 270 to 300 ° C. Then, it introduce | transduces into the 2nd reactor 34 which has a 2nd catalyst with the hydrogen gas inject | poured into the heater 32, and turns into hydrogen sulfide and water by following formula (4). The produced hydrogen sulfide and water are introduced into the quencher 36 through the pipe L12 and separated into water and a gas fraction (hydrogen sulfide). Water is discharged out of the sulfur recovery device 1 from the bottom of the quencher 36. On the other hand, hydrogen sulfide is introduced into the gas absorption tower 38 through the pipes L14 and L16, and is absorbed by the absorption liquid introduced into the gas absorption tower 38 through the pipe L24. The absorbing liquid that has absorbed hydrogen sulfide is discharged out of the sulfur recovery apparatus 1 from the gas absorption tower 38 through the pipe L26.

SO ₂ + 3H ₂ → H ₂ S + 2H ₂ O (4)

  The absorption process can be performed in parallel with the combustion process. That is, while performing the combustion process in the sulfur recovery unit 10 and the gas absorption unit 20, the absorption process can be performed in the gas absorption unit 20 using sulfur dioxide generated in the combustion process.

  Therefore, when the combustion removal of iron sulfide is completed in the combustion process and sulfur dioxide is no longer generated, the absorption process is also ended.

  After completion of the combustion process and the absorption process, for example, the temperature of the sulfur recovery device 1 can be lowered to near room temperature, and each device of the sulfur recovery device 1 can be opened. The sulfur recovery unit can also be opened in the atmosphere.

According to the operation method of the sulfur recovery device of the present embodiment, after the operation of the sulfur recovery device 1 is stopped, when each device such as the condenser 16, the first reactor 14, and the heat exchanger (not shown) is opened, Since iron sulfide is sufficiently removed, combustion of iron sulfide when the device is opened can be sufficiently prevented. In this operation method, it is possible to perform a combustion process in which iron sulfide is burned while the valve V4 is opened and the valve V2 is closed. Therefore, it is possible to sufficiently reduce the emissions into the atmosphere of air pollutants such as SO _x.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

Example 1
The operation of stopping the operation of the sulfur recovery apparatus 1 shown in FIG. 1 was performed as follows.

[Gas purge process]
Supply of hydrogen gas was started to the reaction furnace 12 of the sulfur recovery apparatus 1 that had been in steady operation for a predetermined period. With the start of supply of hydrogen gas, the supply amount of hydrogen sulfide gas (acid gas) was gradually reduced and the supply amount of hydrogen gas to the reaction furnace 12 was gradually increased. After sufficiently increasing the supply amount of hydrogen gas, the supply of hydrogen sulfide gas was stopped. Hydrogen gas supplied to the reaction furnace 12 and an amount of air that gives a stoichiometric air-fuel ratio to the hydrogen gas were supplied. By continuously supplying hydrogen gas and air for a while, the atmosphere in the sulfur recovery apparatus 1 was replaced with combustion gas (hot inert gas).

  The 1st reactor 14 was cooled gradually and the temperature of the sulfur collection | recovery part 10 was 180-230 degreeC.

[Combustion process and absorption process]
The ratio of air to hydrogen gas supplied to the reaction furnace 12 was 101 to 110% by mass based on the theoretical air-fuel ratio (100% by mass). Thereby, the oxygen concentration in the 1st reactor 14 was maintained in the range of 0-1 volume%, and the iron sulfide adhering to the inside of each apparatus which comprises the sulfur collection | recovery part 10 of the sulfur collection | recovery apparatus 1 was burned and removed. The oxygen concentration was measured using a commercially available gas sensor at the outlet of the reaction furnace 12 and the outlet of the condenser 16.

  Sulfur dioxide generated by the combustion of iron sulfide was introduced into a second reactor 34 having a second catalyst for hydrogenation reaction together with hydrogen gas injected by the heater 32 and converted into hydrogen sulfide and water. . This hydrogen sulfide was introduced into the gas absorption tower 38 and absorbed by the absorption liquid (diisopropanolamine). The absorbing solution that absorbed the hydrogen sulfide was discharged out of the sulfur recovery apparatus 1 from the gas absorption tower 38 through the pipe L26. On the other hand, the combustion gas (off-gas) from which hydrogen sulfide was removed was introduced into the combustor 39 through the pipe L22. The sulfur dioxide concentration in the exhaust gas discharged from the combustor 39 was measured using a commercially available gas concentration measuring device. The concentration of sulfur dioxide in the exhaust gas at the time of the shutdown operation changed from several tens to several hundred ppm.

  The combustion process and the absorption process were completed when no heat generation due to the combustion of iron sulfide was detected and no sulfur dioxide was generated. The time required from the start of the gas purge process of the sulfur recovery apparatus 1 to the end of the combustion process and the absorption process was 62 hours. During the combustion process and the absorption process, V2 was closed and V4 was kept open.

(Comparative Example 1)
The operation of stopping the operation of the sulfur recovery device 3 shown in FIG. 2 was performed as follows.

  Supply of hydrogen gas was started to the reaction furnace 112 of the sulfur recovery apparatus 3 that had been in steady operation for a predetermined period. As the supply of hydrogen gas started, the supply amount of hydrogen sulfide gas (acid gas) was gradually reduced and the supply amount of hydrogen gas to the reaction furnace 112 was gradually increased. After sufficiently increasing the supply amount of hydrogen gas, the supply of hydrogen sulfide gas was stopped. Air was supplied to the reaction furnace 112 at a stoichiometric air-fuel ratio with respect to the amount of hydrogen gas supplied to the reaction furnace 112. By continuously supplying hydrogen gas and air for a while, the atmosphere in the sulfur recovery device 3 was replaced with combustion gas (hot inert gas).

  By closing V104 and opening V102, the flow of combustion gas from the sulfur recovery unit 100 to the gas absorption unit 200 was blocked.

  The ratio of air to hydrogen gas supplied to the reaction furnace 112 was 120 to 170% by volume based on the theoretical air-fuel ratio (100% by mass). Thereby, the iron sulfide adhering to the inside of each device constituting the sulfur recovery unit 100 of the sulfur recovery device 3 was removed by combustion.

  Sulfur dioxide generated with the combustion of iron sulfide adhering to the inside of the sulfur recovery unit 100 was introduced into the combustor 139 through the valve V102 and the pipe L108. The sulfur dioxide concentration in the exhaust gas discharged from the combustor 139 was measured using a commercially available gas concentration meter. The concentration of sulfur dioxide in the exhaust gas during the shutdown operation was several tens of times that of Example 1.

  The operation was terminated when no heat generation due to the combustion of iron sulfide was detected and no sulfur dioxide was generated. The time required from the start of the supply of hydrogen gas to the end of the combustion of iron sulfide was 42 hours.

It is a schematic block diagram of the sulfur collection | recovery apparatus for describing suitable embodiment of the operating method of this invention. It is a schematic block diagram of the sulfur collection | recovery apparatus for demonstrating the conventional operating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,3 ... Sulfur recovery apparatus, 10,100 ... Sulfur recovery part, 12,112 ... Reactor, 14,114 ... 1st reactor, 16,116 ... Condenser, 20,200 ... Gas absorption part, 30,300 ... Combustion section, 32, 132 ... Heater, 34, 134 ... Second reactor, 36, 136 ... Quencher, 37, 137 ... Blower, 38, 138 ... Gas absorption tower, 39, 139 ... Combustor.

Claims (2)

A sulfur recovery unit comprising: a reaction furnace that burns hydrogen sulfide to generate sulfur dioxide; and a first reactor that has a first catalyst that generates sulfur by causing a Claus reaction between the sulfur dioxide and hydrogen sulfide; and A second reactor having a second catalyst for hydrogenating the sulfur dioxide produced in the sulfur recovery section to produce hydrogen sulfide; and an absorption tower for absorbing the hydrogen sulfide produced in the second reactor into an absorbent. And a method for operating a sulfur recovery device comprising a gas absorption part comprising:
When the sulfur recovery device is shut down,
The oxygen concentration in the first reactor is maintained at 0 to 1% by volume by supplying air for burning the fuel gas together with the fuel gas containing hydrogen as a main component to the reactor at an air / fuel ratio exceeding the stoichiometric air / fuel ratio. While burning the iron sulfide adhering to the inside of the sulfur recovery unit,
An absorption step of hydrogenating sulfur dioxide generated by the combustion of the iron sulfide in the second reactor of the gas absorption unit to generate hydrogen sulfide and absorbing the hydrogen sulfide with the absorbing liquid. Operation method of recovery device.   Before the combustion step, air for burning the fuel gas together with the fuel gas containing hydrogen as a main component is supplied to the reactor at an air-fuel ratio below the stoichiometric air-fuel ratio, and the first reactor is kept at 230 ° C. or below. The operation method of the sulfur recovery apparatus according to claim 1, further comprising a gas purge step for lowering the temperature.

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