CN114515509B - Shutdown sulfur removal device and method for sulfur recovery system - Google Patents
Shutdown sulfur removal device and method for sulfur recovery system Download PDFInfo
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- CN114515509B CN114515509B CN202011303959.4A CN202011303959A CN114515509B CN 114515509 B CN114515509 B CN 114515509B CN 202011303959 A CN202011303959 A CN 202011303959A CN 114515509 B CN114515509 B CN 114515509B
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- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 title claims abstract description 377
- 229910052717 sulfur Inorganic materials 0.000 title claims abstract description 264
- 239000011593 sulfur Substances 0.000 title claims abstract description 262
- 238000000034 method Methods 0.000 title claims abstract description 153
- 238000011084 recovery Methods 0.000 title claims abstract description 48
- 239000007789 gas Substances 0.000 claims abstract description 306
- 239000007788 liquid Substances 0.000 claims abstract description 129
- 238000002485 combustion reaction Methods 0.000 claims abstract description 107
- 238000003303 reheating Methods 0.000 claims abstract description 59
- 239000003054 catalyst Substances 0.000 claims abstract description 57
- 239000002918 waste heat Substances 0.000 claims abstract description 29
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 91
- 239000002737 fuel gas Substances 0.000 claims description 79
- 229910052757 nitrogen Inorganic materials 0.000 claims description 44
- 230000001105 regulatory effect Effects 0.000 claims description 31
- 238000010438 heat treatment Methods 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 9
- 239000003570 air Substances 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 4
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 11
- 238000007872 degassing Methods 0.000 description 11
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 230000008016 vaporization Effects 0.000 description 6
- 229910001873 dinitrogen Inorganic materials 0.000 description 5
- 238000000746 purification Methods 0.000 description 5
- 239000003345 natural gas Substances 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 239000003546 flue gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000009834 vaporization Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 2
- -1 process gas Chemical compound 0.000 description 2
- 238000010926 purge Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/88—Handling or mounting catalysts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8603—Removing sulfur compounds
- B01D53/8609—Sulfur oxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/02—Preparation of sulfur; Purification
- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biomedical Technology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Health & Medical Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
The embodiment of the invention discloses a shutdown sulfur removal device and a sulfur removal method for a sulfur recovery system, and relates to the field of petrochemical industry. In the shutdown sulfur removal device, a main combustion furnace, a waste heat boiler, a primary Claus reactor, a secondary condenser, a secondary reheating furnace, a secondary Claus reactor, a tertiary condenser and a tail gas catcher are sequentially communicated through pipelines; the top outlet of the tail gas catcher is divided into a first branch and a second branch, the first branch is connected with the inlet end of the steam ejector, and the second branch is connected with the tail gas treatment unit; the outlet end of the steam injector is connected with the main combustion furnace; the second-stage condenser, the third-stage condenser and the tail gas catcher are respectively connected with the liquid sulfur pool. The sulfur removal method and the sulfur removal device provided by the embodiment of the invention can effectively reduce sulfur removal SO during the shutdown period of the sulfur recovery system 2 The concentration fluctuation range improves the sulfur removal efficiency of the catalyst bed and shortens the downtime of the sulfur recovery system.
Description
Technical Field
The embodiment of the invention relates to the technical field of sulfur recovery, in particular to a shutdown sulfur removal device and a sulfur removal method for a sulfur recovery system.
Background
In a sulfur recovery unit of a natural gas purification plant or a refinery, particularly a low temperature claus sulfur recovery unit, it is necessary to remove elemental sulfur and a small amount of FeS adhering to the interstices of the claus reactor catalyst bed prior to shutdown or maintenance.
In the related art, in order to increase the flow of process gas in the whole sulfur removal process, part of nitrogen is added into the furnace end of the main combustion furnace of the sulfur recovery device, heating nitrogen is adopted to remove sulfur from the catalyst bed layer of the Claus reactor of the sulfur recovery device, but the treatment capacity of an air nitrogen system of a natural gas purification plant is limited, and in the shutdown process of the purification plant, a large amount of nitrogen is required for blowing the desulfurization dehydration device, so that the nitrogen amount required by the sulfur recovery device cannot meet the requirement of increasing the flow of the process gas through continuous nitrogen addition, and the sulfur removal rate is lower.
Disclosure of Invention
The embodiment of the application provides a shutdown sulfur removal device and a sulfur removal method for a sulfur recovery system, which are used for solving the problem of low sulfur removal rate caused by the fact that the nitrogen quantity cannot meet the process air flow in the related technology.
The technical proposal is as follows:
in a first aspect, there is provided a shutdown sulfur removal device for a sulfur recovery system, the shutdown sulfur removal device comprising: the device comprises a main combustion furnace, a waste heat boiler, a primary Claus reactor, a secondary condenser, a secondary reheating furnace, a secondary Claus reactor, a tertiary condenser, a tail gas catcher, a liquid sulfur pool, a steam injector and a tail gas treatment unit;
The main combustion furnace, the waste heat boiler, the primary claus reactor, the secondary condenser, the secondary reheating furnace, the secondary claus reactor, the tertiary condenser and the tail gas catcher are sequentially communicated through pipelines;
the top outlet of the tail gas catcher is divided into a first branch and a second branch, the first branch is connected with the inlet end of the steam ejector, and the second branch is connected with the tail gas treatment unit;
the outlet end of the steam injector is connected with the main combustion furnace;
the second-stage condenser, the third-stage condenser and the tail gas catcher are respectively connected with the liquid sulfur pool.
Optionally, the main burner comprises a fuel gas inlet for admitting fuel gas into the main burner, an air inlet for admitting air into the main burner, and a temperature-regulated steam inlet;
the outlet end of the steam ejector is connected with a temperature-adjusting steam inlet.
Optionally, the exhaust gas trap comprises: a top outlet and a first liquid sulfur outlet;
the secondary condenser comprises a second liquid sulfur outlet;
the tertiary condenser comprises a third liquid sulfur outlet;
the second liquid outlet of the second-stage condenser, the third liquid sulfur outlet of the third-stage condenser and the first liquid sulfur outlet of the tail gas catcher are respectively connected with the liquid sulfur pool.
Optionally, a first-stage condenser and a first-stage reheating furnace are arranged between the waste heat boiler and the first-stage claus reactor, the first-stage condenser comprises a fourth liquid sulfur outlet, and the fourth liquid sulfur outlet is connected with the liquid sulfur pool.
Optionally, an outlet end of the steam injector is provided with an injector outlet flow regulating valve, the outlet end of the steam injector is divided into two paths after passing through the injector outlet flow regulating valve, one path is connected with a temperature-regulating steam inlet through a circulating pipeline, and the other path is connected with the tail gas treatment unit through a vent valve.
Optionally, the shutdown sulfur removal device further comprises a pressure regulating valve disposed on the second leg.
In a second aspect, there is provided a method of sulfur removal employing the shutdown sulfur removal apparatus described above, the method comprising:
heating and mixing fuel gas, air, nitrogen and circulating tail gas in a main combustion furnace to form process gas;
the method comprises the steps that after a process gas is cooled by an exhaust-heat boiler, the process gas enters a first-stage claus reactor, elemental sulfur in a catalyst bed of the first-stage claus reactor is vaporized, elemental sulfur forms elemental sulfur vapor, the elemental sulfur vapor and the process gas enter a second-stage condenser to be cooled, the elemental sulfur vapor is condensed and separated into liquid sulfur and enters a liquid sulfur pool, the cooled process gas enters a second-stage reheating furnace to be heated, the heated process gas enters the second-stage claus reactor, the elemental sulfur in the catalyst bed of the second-stage claus reactor is vaporized to form elemental sulfur vapor, the elemental sulfur vapor and the process gas formed enter a third-stage condenser to be cooled, the elemental sulfur vapor is condensed and separated into liquid sulfur and enters a tail gas catcher, the cooled process gas and the residual elemental sulfur vapor which is not condensed and separated enter the tail gas catcher to trap the liquid sulfur and form the liquid sulfur and the liquid sulfur pool, and the tail gas is discharged from a top outlet of the tail gas catcher;
Part of the tail gas enters the steam injector through the first branch, is pressurized by the steam injector and enters the main combustion furnace;
the other part of the tail gas enters the tail gas treatment unit through the second branch.
Optionally, after a part of the tail gas is pressurized by the steam injector, the tail gas enters a temperature-adjusting steam inlet as circulating tail gas through a circulating tail gas pipeline, the flow of the circulating tail gas is controlled by an outlet flow regulating valve of the injector, and the circulating tail gas with excessive flow enters the tail gas treatment unit after being emptied through an emptying valve.
Optionally, the process gas is cooled to 280-320 ℃ by a waste heat boiler.
Optionally, the mass flow ratio of the fuel gas to the circulating tail gas is 2-4:1; and/or
The pressure of the circulating tail gas is 20-40 kPa.
The technical scheme provided by the embodiment of the application has the beneficial effects that at least:
according to the shutdown sulfur removal device and the shutdown sulfur removal method for the sulfur recovery system, provided by the embodiment of the application, the circulating tail gas is returned and mixed with fuel gas, air and nitrogen in a heating way to be used as process gas, so that the number of steps is increasedThe process air flow reduces the consumption of nitrogen and saves the nitrogen consumption; the process gas is used for removing the simple substance sulfur in the catalyst bed layer by vaporization, the formed simple substance sulfur vapor flows along with the process gas, the formed simple substance sulfur vapor is cooled and separated into liquid sulfur, and the rest process gas is pressurized by a steam injector and then returned to be used as circulating tail gas, SO that the circulating recovery of the tail gas is realized, and the sulfur removal SO during the shutdown period of a sulfur recovery system can be effectively reduced 2 Concentration fluctuation range, improved catalyst bed sulfur removal efficiency, shortened sulfur recovery system downtime, and simple process flow; according to the shutdown sulfur removal device for the sulfur recovery system, provided by the embodiment of the application, the top outlet of the tail gas catcher is connected with the steam ejector, so that the recovered tail gas is returned to the main combustion furnace, and the shutdown sulfur removal device has the advantages of simple structure, low cost and wide application prospect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a schematic structural diagram of a shutdown sulfur removal device of a sulfur recovery system in accordance with an embodiment of the present application;
fig. 2 shows a schematic structural view of a shutdown sulfur removal device of another sulfur recovery system in accordance with an embodiment of the present application.
Reference numerals denote:
1-an air inlet;
2-fuel gas inlet;
3-nitrogen pipeline;
4-sour gas pipeline;
5-a main fuel furnace;
6-a waste heat boiler;
7-a first-stage condenser;
8-a liquid sulfur pool;
9-a first air inlet;
10-a first fuel gas inlet;
11-a primary reheating furnace;
a 12-stage claus reactor;
13-a secondary condenser;
14-a second air inlet;
15-a second fuel gas inlet;
16-secondary reheating furnace;
a 17-secondary claus reactor;
18-three-stage condenser;
19-an exhaust gas trap;
20-a recycle tail gas line;
21-a steam injector;
22-an exhaust gas treatment unit;
23-an injector outlet flow regulator valve;
24-pressure regulating valve;
25-an air release valve;
26-tempering steam inlet;
27-a first branch;
28-a second branch.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the following embodiments of the present application will be described in further detail.
In the normal production process of a Claus sulfur recovery device of a natural gas purification plant or a refinery, H in the process gas is usually recovered 2 S、SO 2 The claus reaction takes place to generate elemental sulfur, the elemental sulfur mainly takes the form of S 8 The morphology exists that with the operation of the plant, part of the sulfur vapor will condense in the pore structure of the catalyst surface, especially in the low temperature claus sulfur recovery process, where H in the process gas 2 S、SO 2 Elemental sulfur generated by the low-temperature Claus reaction is deposited in the void structure of the catalyst, the void deposited elemental sulfur of the catalyst is regenerated by switching the thermal state and the cold state Claus reactor, and the catalyst is not completely regenerated in the daily production running process due to factors such as low load of the device, long-time running abrasion of the catalyst and the likePart of elemental sulfur is deposited in the voids.
Meanwhile, as the operation time of the sulfur recovery device is prolonged, H 2 S、SO 2 The device and equipment pipeline are corroded to generate substances such as FeS, the substances are stored in a catalyst bed layer of a Claus reactor, the FeS has a low ignition point, and the spontaneous combustion is easy to cause the combustion of the simple substance sulfur stored in the catalyst bed layer to generate SO 2 SO as to lead the tail gas to be discharged into the SO 2 Increases the environmental risk, emits a large amount of heat during the combustion process, causes deactivation of the catalyst, and damages the claus reactor and other equipment when serious.
Therefore, before the sulfur recovery device is shut down or overhauled, the elemental sulfur and a small amount of FeS attached in the gaps of the catalyst bed layer of the Claus reactor are removed. In the stopping stage of the sulfur recovery device, when the elemental sulfur in the gaps of the catalyst bed is removed, in order to improve the sulfur removal rate, the SO (sulfur oxide) discharged from the tail gas is reduced 2 It is desirable to provide a sulfur recovery system shutdown sulfur removal apparatus and method for treating tail gas.
In the embodiment of the invention, during the normal operation of the sulfur recovery device, the air from the main fan and the acid gas from the desulfurization unit enter the main combustion furnace, and one third of H in the acid gas 2 S and O in air 2 Combustion to produce SO 2 And release a large amount of heat, two thirds of H is left in the acid gas 2 S and SO 2 The method comprises the steps that claus reaction is carried out in a main combustion furnace to generate elemental sulfur, the generated elemental sulfur enters a waste heat boiler along with high-temperature process gas in the form of elemental sulfur vapor, the elemental sulfur enters a first-stage condenser for further cooling after being cooled by the waste heat boiler, the elemental sulfur vapor is condensed and separated into liquid sulfur, the liquid sulfur is stored in a liquid sulfur tank for degassing, the cooled process gas is heated by a first-stage reheating furnace to meet the requirement of the reaction temperature of the first-stage claus reactor, heat is provided by heat release of fuel gas and air, the process gas heated by the first-stage reheating furnace enters the first-stage claus reactor, and H in the process gas is 2 S and SO 2 The catalyst bed layer of the first-stage claus reactor continuously generates claus reaction to generate elemental sulfur vapor, and the elemental sulfur vapor enters a second-stage condenser along with process gas to be cooled, so that the elemental sulfur vapor is evaporated The gas is condensed and separated into liquid sulfur, the liquid sulfur is degassed and stored in a liquid sulfur tank, the cooled process gas enters a secondary reheating furnace to be heated so as to meet the temperature requirement of a secondary Claus reactor, the heat of the secondary reheating furnace is provided by the combustion heat release of fuel gas and air, the heated process gas enters the secondary Claus reactor, and H in the process gas 2 S and SO 2 The method comprises the steps that a Claus reaction is continuously carried out on a catalyst bed layer of a secondary Claus reactor to generate elemental sulfur vapor, the elemental sulfur vapor enters a tertiary condenser along with process gas to be cooled, the elemental sulfur vapor is condensed and separated into liquid sulfur, the liquid sulfur is degassed and stored in a liquid sulfur tank, the cooled process gas enters a tail gas catcher, the tail gas catcher catches and separates residual elemental sulfur vapor in the process gas, the liquid sulfur which is caught and separated enters a liquid sulfur tank to be degassed and stored, and the process gas which is caught and separated enters a tail gas treatment unit, such as a tail gas treatment device or a tail gas incinerator.
In one aspect, an embodiment of the present invention provides a shutdown sulfur removal device for a sulfur recovery system, as shown in fig. 1 and fig. 2, where the sulfur removal device includes: a main combustion furnace 5, a waste heat boiler 6, a primary claus reactor 12, a secondary condenser 13, a secondary reheating furnace 16, a secondary claus reactor 17, a tertiary condenser 18, a tail gas catcher 19, a liquid sulfur tank 8, a steam injector 21 and a tail gas treatment unit 22;
The main combustion furnace 5, the waste heat boiler 6, the primary claus reactor 12, the secondary condenser 13, the secondary reheating furnace 16, the secondary claus reactor 17, the tertiary condenser 18 and the tail gas catcher 19 are sequentially communicated through pipelines;
the top outlet of the exhaust gas catcher 19 is divided into a first branch 27 and a second branch 28, the first branch 27 is connected with the inlet end of the steam injector 21, and the second branch 28 is connected with the exhaust gas treatment unit 22;
the outlet end of the steam injector 21 is connected with the main combustion furnace 5;
the secondary condenser 13, the tertiary condenser 18 and the tail gas trap 19 are respectively connected with the liquid sulfur tank 8, as shown in fig. 2.
According to the shutdown sulfur removal device provided by the embodiment of the invention, the steam ejector 21 is connected to the first branch 27 of the top outlet of the tail gas catcher 19, and the outlet end of the steam ejector 21 is connected with the main combustion furnace 5, so that the tail gas discharged by the tail gas catcher 19 is returned to the main combustion furnace 5 as circulating tail gas, the flow rate of the process gas is increased, the consumption of the nitrogen gas is reduced, and the recycling of the tail gas is realized.
Optionally, the exhaust gas treatment unit 22 is configured to treat the exhaust gas entering the exhaust gas treatment unit 22, and the exhaust gas treatment unit 22 is an exhaust gas treatment device or an incinerator.
According to an embodiment of the present invention, the main combustion furnace 5 includes a fuel gas inlet 2, an air inlet 1, and a temperature-adjusting steam inlet 26, the fuel gas inlet 2 for introducing fuel gas into the main combustion furnace 5, the air inlet 1 for introducing air into the main combustion furnace 5; the outlet end of the steam injector 21 is connected to a tempering steam inlet 26.
Optionally, both the nitrogen line 5 and the sour gas line 4 are connected to a tempering steam inlet 26, so that nitrogen enters the main burner 5 through the nitrogen line 5 from the tempering steam inlet 26.
The fuel gas and air respectively enter the combustion furnace 5 through the fuel gas inlet 2 and the air inlet 1 so as to heat in the combustion furnace 5 to provide heat, and the circulating tail gas and nitrogen can enter the main combustion furnace 5 through the temperature-adjusting steam inlet 26 so that the fuel gas, the air, the nitrogen and the circulating tail gas are heated and mixed in the main combustion furnace 5 to form process gas for vaporizing and removing the elemental sulfur deposited in the catalyst beds of the claus reactors at different levels.
Optionally, the exhaust gas trap 19 comprises: a top outlet and a first liquid sulfur outlet; the second-stage condenser 13 comprises a second liquid sulfur outlet, the third-stage condenser 18 comprises a third liquid sulfur outlet, and the second liquid sulfur outlet of the second-stage condenser 13, the third liquid sulfur outlet of the third-stage condenser 18 and the first liquid sulfur outlet of the tail gas catcher 19 are respectively connected with the liquid sulfur tank 8.
The tail gas collector 19 is used for collecting and treating the gas entering the tail gas collector, for example, treating the process gas and the residual elemental sulfur vapor, so that the residual elemental sulfur vapor is condensed and separated into liquid sulfur to be stored in the liquid sulfur tank 8 for degassing, and the secondary condenser 13 and the tertiary condenser 18 can be used for condensing and separating the entering elemental sulfur vapor to form liquid sulfur to be stored in the liquid sulfur tank 8 for degassing.
Optionally, a primary condenser 7 and a primary reheating furnace 11 are connected between the waste heat boiler 6 and the primary claus reactor 12, i.e. the sulfur removal device comprises a primary combustion furnace 5, a waste heat boiler 6, a primary condenser 7, a primary reheating furnace 11, a primary claus reactor 12, a secondary condenser 13, a secondary reheating furnace 16, a secondary claus reactor 17, a tertiary condenser 18 and an exhaust gas trap 19, which are connected in sequence, as shown in fig. 1.
The waste heat boiler 6 is used for cooling the process gas entering the waste heat boiler, the cooled process gas can enter the first-stage condenser 7 for further cooling, the further cooled process gas enters the first-stage reheating furnace 11 for heating, and the first-stage condenser 7 can condense and separate elemental sulfur vapor flowing along with the process gas (comprising circulating tail gas) into liquid sulfur and then into a liquid sulfur pool, so that sulfur removal is further realized.
In an alternative embodiment, after the elemental sulfur vapor enters the primary condenser 7, the secondary condenser 13 and the tertiary condenser 18 along with the process gas, the liquid sulfur is cooled and separated, the separated liquid sulfur enters a liquid sulfur seal respectively, the liquid sulfur flows into a degassing tank through the liquid sulfur seal, and H in the liquid sulfur is removed 2 And after S, the sulfur enters a liquid sulfur pool 8, and optionally, the sulfur is pumped to a sulfur forming unit through a liquid sulfur pump for preparing sulfur.
According to the embodiment of the invention, an outlet end of the steam injector 21 is provided with an injector outlet flow regulating valve 23, the outlet end of the steam injector 21 is divided into two paths after passing through the injector outlet flow regulating valve 23, one path is connected with a temperature-regulating steam inlet 26 through a circulating pipeline 20, and the other path is connected with an exhaust gas treatment unit 22 through a vent valve 25.
The steam ejector 21 is used for pressurizing the tail gas entering the main combustion furnace 5, the pressurized tail gas is returned to the main combustion furnace 5 as circulating tail gas, the flow rate of the process gas is increased, the temperature of the main combustion furnace 5 can be reduced as temperature-adjusting steam, in the process that the circulating tail gas returns to the main combustion furnace 5 through the circulating pipeline 20, the flow rate of the circulating tail gas returning to the main combustion furnace 5 is controlled by adopting the ejector outlet flow rate regulating valve 23, and the circulating tail gas with the redundant flow rate is discharged to the tail gas treatment unit 22 through the discharge valve 25.
According to the shutdown sulfur removal device for the sulfur recovery system, provided by the embodiment of the invention, the top outlet of the tail gas catcher 19 is connected with the steam ejector 21, so that the tail gas discharged from the top outlet of the tail gas catcher 19 is pressurized and returned to the main combustion furnace 5, the flow of process gas is increased, the consumption of nitrogen amount is reduced, the sulfur removal efficiency is improved, and the shutdown time of the sulfur recovery system is shortened.
Another aspect of an embodiment of the present invention provides a shutdown sulfur removal method for a sulfur recovery system, the method comprising:
and step 1, heating and mixing fuel gas, air, nitrogen and circulating tail gas to form process gas.
In the embodiment of the invention, air, fuel gas, nitrogen and circulating tail gas are heated and mixed in the main combustion furnace 5 to form high-temperature inert flue gas, namely process gas.
Wherein, air is output from a main fan outlet and enters the main combustion furnace 5 through an air inlet 1, fuel gas is fuel gas for starting and stopping, fuel gas enters the main combustion furnace 5 through a fuel gas inlet 2, nitrogen enters the main combustion furnace 5 through a temperature-adjusting steam inlet 26 through a nitrogen pipeline 3 by an air-nitrogen system, circulating tail gas is provided by a steam injector 21, and nitrogen and circulating tail gas enter the main combustion furnace 5 through the temperature-adjusting steam inlet 26.
In the embodiment of the invention, fuel gas is combusted and heated in the main combustion furnace 5, and a large amount of heat is released when the fuel gas and air are equivalently combusted, and because the main combustion furnace 5 is made of metal, the main combustion furnace 5 can be damaged due to the fact that the temperature is too high (for example, higher than 1200 ℃), so that in order to protect the main combustion furnace 5, the main combustion furnace 5 is protected by introducing circulating tail gas into the main combustion furnace 5 to replace temperature-regulating steam, and the temperature of the main combustion furnace is reduced.
Meanwhile, nitrogen is taken as inert gas and does not chemically react with sulfur, ferrous sulfide, sulfur steam and other substances in the Claus system, and under the condition of meeting the nitrogen requirement, the air nitrogen system adds nitrogen into the main combustion furnace 5 through the nitrogen pipeline 3, so that the air flow and heat in the whole sulfur removal process can be increased.
In the embodiment of the invention, air, fuel gas, nitrogen and circulating tail gas enter the main combustion furnace 5 to be mixed, and high-temperature inert flue gas, namely process gas, is formed by combustion and heating of the fuel gas.
When the sulfur recovery system is shut down for sulfur removal, the boundary area valve on the acid gas pipeline 4 is required to be closed, the acid gas is stopped from entering the main combustion furnace 5, the fuel gas interlocking valve is opened, so that the fuel gas enters the main combustion furnace 5, and the switching of the fuel gas and the acid gas is completed.
Optionally, in step 1, the volumetric air to fuel gas flow ratio in the main fuel furnace 5 is (9-10): 1, e.g. 9.8:1.
Alternatively, in step 1, the temperature of the main burner 5 is controlled to 1050-1150 ℃, for example 1100 ℃.
In order to avoid the main combustion furnace 5 forming high temperature, the main combustion furnace 5 is protected and controlled, and the weight flow ratio of the circulating tail gas to the fuel gas is (2-4): 1, wherein the density of the fuel gas is 0.717kg/m 3 . The flow rate of the nitrogen gas is not particularly limited, and is determined according to the amount of nitrogen gas that can be supplied in actual cases.
Alternatively, in step 1, the pressure of the fuel gas is between 0.3 and 0.5MPa, for example 0.4MPa; the nitrogen pressure is 0.5 to 0.7MPa, for example 0.6MPa; the air pressure is 80 to 90kPa, for example 80kPa; the steam injector 21 pressurizes the circulated exhaust gas to 20 to 40kPa, for example, 30kPa, and returns it to the main burner 5.
Step 2, cooling process gas through a waste heat boiler 6, then feeding the cooled process gas into a first-stage claus reactor 12, vaporizing the elemental sulfur in a catalyst bed layer of the first-stage claus reactor 12, forming elemental sulfur vapor by the elemental sulfur, feeding the elemental sulfur vapor and the process gas into a second-stage condenser 13 for cooling, condensing and separating the elemental sulfur vapor into liquid sulfur into a liquid sulfur pool 8, feeding the cooled process gas into a second reheating furnace 16 for heating, feeding the heated process gas into a second-stage claus reactor 17, vaporizing the elemental sulfur in the catalyst bed layer of the second-stage claus reactor 17 to form elemental sulfur vapor, feeding the formed elemental sulfur vapor and the process gas into a third-stage condenser 18 for cooling, condensing and separating the elemental sulfur vapor into liquid sulfur pool 8, feeding the cooled process gas and residual elemental sulfur vapor which is not condensed and separated into a tail gas catcher 19, capturing and separating the residual elemental sulfur vapor into the liquid sulfur pool 8, and discharging the obtained tail gas from a top outlet of the tail gas catcher 19.
In one embodiment, in step 2, the process gas enters the waste heat boiler 6 from the main combustion furnace 5, is cooled by the waste heat boiler 6, enters the primary claus reactor 12, and vaporizes the elemental sulfur deposited in the catalyst bed gaps in the primary claus reactor 12, so that the elemental sulfur forms elemental sulfur vapor.
Optionally, the process gas is cooled to 280-320 ℃, for example to 300 ℃, by means of a waste heat boiler 6.
In another embodiment, in step 2, the process gas enters the waste heat boiler 6 from the main combustion furnace 5, is cooled by the waste heat boiler 6, is cooled by the first-stage condenser 7, is heated by the first-stage reheating furnace 11, and enters the first-stage claus reactor 12, so that the elemental sulfur in the catalyst bed of the first-stage claus reactor 12 is vaporized, namely, the elemental sulfur in the gaps of the catalyst bed is vaporized and removed, and elemental sulfur vapor is formed.
Optionally, cooling to 165-175 ℃, e.g. 170 ℃, is performed via the primary condenser 7.
In the embodiment of the invention, the primary condenser 7 can cool residual elemental sulfur vapor flowing along with the process gas (such as residual elemental sulfur vapor in the circulating tail gas), the residual elemental sulfur vapor is cooled and separated into liquid sulfur, and the liquid sulfur enters the liquid sulfur tank 8 from the fourth liquid sulfur outlet.
Optionally, the primary reheating furnace 11 is heated to 280-320 ℃, such as 300 ℃. The process gas of 280-320 deg.c (300 deg.c, for example) enters the first-stage claus reactor 12 to gasify and eliminate the deposited sulfur in the gaps in the catalyst bed to form sulfur vapor.
Optionally, the fuel gas and the air are introduced into the primary reheating furnace 11 for heating to provide heat, the fuel gas enters the primary reheating furnace 11 through the first fuel gas inlet 10, the air enters the primary reheating furnace 11 through the first air inlet 9, and the volume flow ratio of the introduced fuel gas to the air is 1 (9-10), for example, 1:9.8.
Elemental sulfur vapor formed in primary claus reactor 12 flows with the process gas.
The elemental sulfur vapor formed in the primary claus reactor 12 is cooled by the secondary condenser 13 along with the process gas, and then heated by the secondary reheating furnace 16, and enters the secondary claus reactor 17, so that the elemental sulfur in the catalyst bed layer of the secondary claus reactor 17 is vaporized and removed, elemental sulfur vapor is formed, and the elemental sulfur vapor formed in the secondary claus reactor 17 flows along with the process gas.
Optionally, the heat is provided by introducing fuel gas and air into the secondary reheating furnace 16, wherein the fuel gas enters the secondary reheating furnace 16 through the second fuel gas inlet 15, and the air enters the secondary reheating furnace 16 through the second air inlet 14, and the volume flow ratio of the introduced fuel gas to the air is 1 (9-10), such as 1:9.8.
Optionally, the elemental sulfur vapor enters the secondary condenser 13 along with the process gas to be cooled to 165-175 ℃, for example 170 ℃, the elemental sulfur vapor is condensed into liquid sulfur in the secondary condenser 13, the liquid sulfur enters the liquid sulfur tank 8 from a second liquid sulfur outlet of the secondary condenser 13 to be degassed and stored, the cooled process gas enters the secondary reheating furnace 16 to be heated to 280-320 ℃, for example 300 ℃, the heated process gas enters the secondary claus reactor 17, the elemental sulfur deposited in the gaps of the catalyst bed layer in the secondary claus reactor 17 is vaporized and removed, the elemental sulfur vapor is formed, and the elemental sulfur vapor formed in the secondary claus reactor 17 flows along with the process gas.
The elemental sulfur vapor formed in the secondary claus reactor 17 enters the tertiary condenser 18 along with the process gas, the elemental sulfur vapor is cooled and separated by the tertiary condenser 18 to obtain liquid sulfur, the liquid sulfur enters the liquid sulfur tank 8 from the third liquid sulfur outlet for degassing and storage, and the cooled process gas enters the tail gas catcher 19.
Optionally, the process gas and the elemental sulfur vapor are cooled to 165-175 ℃, such as 170 ℃, by a three-stage condenser 18, the cooled process gas enters a tail gas catcher 19, the tail gas catcher 19 catches and separates residual elemental sulfur vapor flowing along with the process gas, the residual elemental sulfur vapor is caught and separated into liquid sulfur, the liquid sulfur enters a liquid sulfur tank 8 from a first liquid sulfur outlet for degassing and storage, and tail gas is discharged from a top outlet of the tail gas catcher 19.
In the embodiment of the invention, low-pressure saturated steam generated by the primary condenser 7, the secondary condenser 13 and the tertiary condenser 18 can provide heat preservation and heat tracing steam for the sulfur removal device, and the rest steam can enter a low-pressure steam system pipe network of the whole plant for other devices after pressure regulation by the pressure regulating valve 24.
Step 3, part of the tail gas enters a steam injector through a first branch, and enters a main combustion furnace after being pressurized by the steam injector; and the other part of the tail gas enters the tail gas treatment unit through the second branch.
In step 3, a part of the exhaust gas discharged from the top outlet of the exhaust gas catcher 19 enters the steam injector 21 through the first branch 27, is pressurized by the steam injector 21 and enters the main combustion furnace 5, and the other part of the exhaust gas enters the exhaust gas treatment unit 22 through the second branch 28.
Alternatively, the tail gas is pressurized by the steam injector 21 and then enters the attemperation steam inlet 26 as a circulating tail gas through the circulating tail gas line 20, and returns to the main burner 5.
In the embodiment of the invention, part of the tail gas discharged from the outlet at the top of the tail gas catcher 19 enters the steam injector 21 through the first branch 27, the steam injector 21 pressurizes the process gas and returns to the temperature-regulating steam inlet 26 of the main combustion furnace 5, SO that the fuel gas, air, nitrogen and circulating tail gas are heated and mixed in the main combustion furnace 5, the process gas flow and heat of the whole sulfur removal device are increased, the nitrogen concentration in the process gas is increased, the formed high-temperature process gas enters all-stage Claus reactors again in sequence to purge and remove sulfur from the catalyst bed, the combustion of elemental sulfur in the catalyst bed due to poor air distribution is reduced, and SO in the system is increased 2 Concentration, reduction of tail gas SO 2 Concentration, simultaneously improves sulfur removal efficiency and temperature rising rate of the catalyst beds, shortens sulfur removal time of the catalyst beds of the Claus reactors at each level, and saves downtime of a sulfur recovery system.
During the shutdown period of the sulfur recovery system, the back pressure of the whole sulfur removal device is controlled by the pressure regulating valve 24, when the pressure is high, the pressure regulating valve 24 is opened, part of tail gas enters the tail gas treatment unit 22, such as the tail gas treatment device or the incinerator, through the pressure regulating valve 24, and when the pressure is low, the pressure regulating valve 24 is closed.
Alternatively, the flow rate of the circulating exhaust gas is controlled by an ejector outlet flow rate adjusting valve 23, and the surplus flow rate of the circulating exhaust gas is discharged to the exhaust gas treatment unit 22 by a discharge valve 25.
Alternatively, the sulfur removal process is ended when the amount of liquid sulfur flowing out of the bottom of the exhaust gas trap 19 is below a preset value.
Alternatively, the sulfur removal process should be performed for at least 24 hours, ensuring that no liquid sulfur flows from the bottom of the tail gas trap 19 to the liquid sulfur reservoir 8.
Optionally, the sulfur removal method further comprises: the primary reheating furnace 11 and the secondary reheating furnace 16 are closed, the air quantity of the main combustion furnace 5 is increased, when the temperatures of all points of the catalyst beds of the Claus reactors at all levels are reduced to 150-155 ℃, such as about 150 ℃, the main combustion furnace 5 is closed, the furnace is stopped, and the fuel gas inlet 2 and the temperature-regulating steam inlet 26 are closed.
Optionally, when no liquid sulfur flows to the liquid sulfur pool 8 from the bottom of the tail gas catcher 19, the primary reheating furnace 11 and the secondary reheating furnace 16 are closed, the fuel gas of the main combustion furnace 5 continues to burn, when the catalyst bed temperature in the primary claus reactor 12 and the secondary claus reactor 17 is reduced to 195-200 ℃, the air quantity of the main combustion furnace 5 is slowly increased, the surplus oxygen content of the whole sulfur removal device is controlled to be 0.5-1%, when the air quantity is excessive, the catalyst bed temperature is ensured to be below 230 ℃, if the surplus oxygen supply quantity is increased to be reduced to stabilize or reduce the catalyst bed temperature, when the catalyst bed temperature is stable and is in a descending trend, the air quantity of the main combustion furnace 5 is gradually increased, when the catalyst bed temperature is reduced to about 150-155 ℃, the main combustion furnace 5 is closed, the fuel gas inlet 2 and the temperature regulating steam inlet 26 are closed, and the sulfur removal process is ended.
According to the shutdown sulfur removal device and the shutdown sulfur removal method for the sulfur recovery system, provided by the embodiment of the invention, the circulating tail gas is returned to be heated and mixed with the fuel gas, the air and the nitrogen to be used as the process gas, so that the flow rate of the process gas is increased, the consumption of the nitrogen is reduced, and the nitrogen consumption is saved; passing through The process gas is used for removing the simple substance sulfur in the catalyst bed layer by vaporization, the formed simple substance sulfur vapor flows along with the process gas, the formed simple substance sulfur vapor is cooled and separated into liquid sulfur, and the rest process gas is pressurized by a steam injector and then returned to be used as circulating tail gas, SO that the circulating recovery of the tail gas is realized, and the sulfur removal SO during the stop period of a sulfur recovery system can be effectively reduced 2 Concentration fluctuation range, improved catalyst bed sulfur removal efficiency, shortened sulfur recovery system downtime, and simple process flow; according to the shutdown sulfur removal device for the sulfur recovery system, provided by the embodiment of the invention, the steam ejector is connected to the outlet at the top of the tail gas catcher, so that the circulating tail gas is returned to the main combustion furnace, the structure is simple, the cost is low, and the shutdown sulfur removal device is suitable for a Claus sulfur recovery device corresponding to a natural gas purification plant or a refining plant, such as a low-temperature Claus sulfur recovery device.
The following will be described in detail by way of examples:
examples
There is provided a shutdown sulfur removal apparatus for a sulfur recovery system, the sulfur removal apparatus comprising: the device comprises a main combustion furnace, a waste heat boiler, a first-stage condenser, a first-stage reheating furnace, a first-stage Claus reactor, a second-stage condenser, a second-stage reheating furnace, a second-stage Claus reactor, a third-stage condenser, a tail gas catcher, a liquid sulfur tank, a steam injector and a tail gas treatment unit;
The main combustion furnace, the waste heat boiler, the primary condenser, the primary reheating furnace, the primary claus reactor, the secondary condenser, the secondary reheating furnace, the secondary claus reactor, the tertiary condenser and the tail gas catcher are sequentially communicated through pipelines;
the top outlet of the tail gas catcher is divided into a first branch and a second branch, the first branch is connected with the inlet end of the steam ejector, the second branch is connected with the tail gas treatment unit, and the second branch is also provided with a pressure regulating valve; the outlet end of the steam ejector is connected with a temperature-adjusting steam inlet of the main combustion furnace;
the first-stage condenser, the second-stage condenser, the third-stage condenser and the tail gas catcher are respectively connected with the liquid sulfur pool;
the outlet end of the steam injector is provided with an injector outlet flow regulating valve, the outlet end of the steam injector is divided into two paths after passing through the injector outlet flow regulating valve, one path is connected with a temperature-regulating steam inlet through a circulating pipeline, and the other path is connected with the tail gas treatment unit through a vent valve.
Sulfur recovery system during normal production:
90kPa of air from the main fan and 90kPa of acid gas from the desulfurization unit enter the main combustion furnace, and one third of H in the acid gas 2 S and O in air 2 Combustion to produce SO 2 The reaction temperature is 1109 ℃, and a large amount of heat is discharged, two thirds of H is left 2 S and generated SO 2 The method comprises the steps that claus reaction is carried out in a main combustion furnace to generate elemental sulfur, the generated elemental sulfur is cooled to 316 ℃ along with high-temperature process gas through a waste heat boiler, the cooled process gas enters a primary condenser to be further cooled to 170 ℃, elemental sulfur vapor is condensed into separated liquid sulfur to be stored in a liquid sulfur pool for degassing, the cooled process gas is heated to 260 ℃ through a primary reheating furnace in order to meet the requirement of the reaction temperature of the primary claus reactor, heat is provided by combustion heat release of fuel gas and air, the heated process gas enters the primary claus reactor, and H in the process gas is removed from the primary claus reactor 2 S and SO 2 The claus reaction is continuously carried out in the catalyst bed layer of the first-stage claus reactor to generate elemental sulfur vapor, the temperature of the process gas leaving the first-stage claus reactor is about 340 ℃, the elemental sulfur vapor enters a second-stage condenser to be cooled to 170 ℃, the elemental sulfur vapor is condensed into separated liquid sulfur to be stored in a liquid sulfur tank for degassing, the cooled process gas enters a second-stage reheating furnace to be heated to 220 ℃ so as to meet the temperature requirement of the second-stage claus reactor, the heat is provided by the combustion heat release of fuel gas and air, the heated process gas enters the second-stage claus reactor, and the residual H of the process gas is obtained 2 S and SO 2 Continuously carrying out a Claus reaction on a catalyst bed layer of a secondary Claus reactor to generate elemental sulfur vapor, increasing the temperature of process gas discharged from the secondary Claus reactor to 245 ℃, cooling to 170 ℃ in a three-stage condenser, condensing the elemental sulfur vapor into separated liquid sulfur, degassing and storing the separated liquid sulfur in a liquid sulfur pond, introducing the cooled process gas and residual elemental sulfur vapor into a tail gas catcher to catch and separate the residual sulfur vapor of the process gas, and catching and separating the residual sulfur vapor into liquid sulfurAnd (3) degassing and storing sulfur in a liquid sulfur pool, capturing and separating process gas, namely tail gas, and enabling the tail gas to enter a tail gas treatment device or a tail gas incinerator.
The liquid sulfur condensed and separated by the first-stage condenser, the second-stage condenser and the third-stage condenser respectively enter a liquid sulfur seal, and the liquid sulfur passing through the liquid sulfur seals of each stage flows into a degassing tank to remove H in the liquid sulfur 2 And S, entering a liquid sulfur pool, and then conveying the liquid sulfur pool to a sulfur forming unit by using a liquid sulfur pump.
During the parking period of the sulfur recovery system:
the method comprises the steps of heating and mixing nitrogen with pressure of 0.6MPa from a start-stop fuel gas with pressure of 0.4MPa from a main fan and a nitrogen pipeline with pressure of 30kPa from a circulating tail gas pipeline in a main combustion furnace to form inert high-temperature flue gas, namely process gas, wherein the volume flow ratio of air to fuel gas is 9.8:1, the weight ratio of the circulating tail gas to the fuel gas is 4:1, the nitrogen flow is determined according to practical conditions, the formed high-temperature process gas is cooled by a waste heat boiler to 300 ℃, the cooled process gas enters a primary condenser to be further cooled to 170 ℃, the cooled process gas is heated to 300 ℃ by a primary reheating furnace, heat is provided by combustion of the fuel gas and the air, the heated process gas enters a primary claus reactor, the catalyst bed of the primary claus reactor is heated by the heated process gas, the formed elemental sulfur in a clearance is removed by vaporization, the formed elemental sulfur enters a secondary condenser along with the process gas to cool the volume flow, the elemental sulfur is condensed to 170 ℃, the cooled elemental sulfur is separated into liquid sulfur to be stored in a liquid sulfur reservoir, the cooled by the reheating furnace enters a secondary sulfur reservoir, the heat is supplied to the secondary sulfur reservoir, the elemental sulfur is removed by the cooling gas enters a secondary sulfur reservoir, the heat is supplied to the secondary sulfur reservoir, the elemental sulfur is removed by the heated elemental sulfur, and the elemental sulfur is separated by the heated process gas enters a primary claus reactor, and the elemental sulfur reservoir, the elemental sulfur is separated by the heat, and enters a secondary sulfur reservoir, and the elemental sulfur is separated by the elemental sulfur, and the elemental sulfur is separated by the heat and enters a catalyst layer by the phase, and the elemental sulfur.
The tail gas is discharged from the top outlet of the tail gas catcher, the tail gas is pressurized by the steam injector and then returns to the temperature-regulating steam inlet of the main combustion furnace as circulating tail gas, the circulating tail gas is heated and mixed with fuel gas, air and nitrogen gas which are started and stopped in the main combustion furnace to form process gas, the flow and heat of the process gas of the whole sulfur removal device are increased, the nitrogen concentration in the process gas is increased, and the process gas with high temperature is fed into the reactor again to purge and remove sulfur from the catalyst bed.
And during the period, the back pressure of the whole system is controlled by the pressure regulating valve, the pressure regulating valve is opened when the pressure is high, part of tail gas enters the tail gas treatment device or the tail gas incinerator through the pressure regulating valve, and the pressure regulating valve is closed when the pressure is low.
The flow of the circulating tail gas is controlled by an outlet flow regulating valve of the ejector, and the circulating tail gas with redundant flow is exhausted to a tail gas treatment device or a tail gas incinerator through an exhaust valve.
In the operation process of the sulfur removal device, when no liquid flow enters the liquid flow pool or the liquid sulfur amount is lower than a set value, the steam ejector closes the primary reheating furnace and the secondary reheating furnace to continuously maintain the combustion of fuel gas in the main combustion furnace, and when the temperatures of all points of a catalyst bed layer in each stage of Claus reactor are reduced to 195 ℃, the air amount of the main combustion furnace is slowly increased to ensure that the excessive O in the system 2 The content is controlled within 0.5% -1%. When the catalyst bed temperature of each stage of Claus reactor is stable and the catalyst bed temperature is in a descending trend, the air quantity of the main combustion furnace can be gradually increased so as to lead the excessive O in the process gas 2 When the temperature of each point of the catalyst bed layers of the first-stage claus reactor, the second-stage claus reactor and the third-stage claus reactor is reduced to about 150 ℃, the main combustion furnace is shut down, the fuel gas is stopped from entering the main combustion furnace, and the sulfur removal is finished.
In summary, the embodiment of the application returns the circulating tail gas pressurized by the steam injector to the main combustion furnace, increases the flow rate of the process gas, reduces the consumption of nitrogen gas, and reduces the sulfur removal SO during the shutdown period of the sulfur recovery system 2 The concentration fluctuation range improves the sulfur removal efficiency and shortens the downtime of the sulfur recovery system.
The foregoing description of the preferred embodiments of the present application should not be taken as limiting the scope of the application, but rather should be construed in view of the appended claims.
Claims (3)
1. A shutdown sulfur removal method for a sulfur recovery system is characterized in that the method is performed by using a shutdown sulfur removal device, wherein,
The shutdown sulfur removal device comprises: the device comprises a main combustion furnace, a waste heat boiler, a first-stage condenser, a first-stage reheating furnace, a first-stage Claus reactor, a second-stage condenser, a second-stage reheating furnace, a second-stage Claus reactor, a third-stage condenser, a tail gas catcher, a liquid sulfur tank, a steam injector, a tail gas treatment unit and a pressure regulating valve;
the main combustion furnace, the waste heat boiler, the primary condenser, the primary reheating furnace, the primary claus reactor, the secondary condenser, the secondary reheating furnace, the secondary claus reactor, the tertiary condenser and the tail gas catcher are sequentially communicated through pipelines;
the main combustion furnace comprises a fuel gas inlet, an air inlet and a temperature-regulating steam inlet, wherein the fuel gas inlet is used for enabling fuel gas to enter the main combustion furnace, the air inlet is used for enabling air to enter the main combustion furnace, the temperature-regulating steam inlet is connected with the outlet end of the steam injector and connected with a nitrogen pipeline and an acid gas pipeline, and is used for enabling circulating tail gas and nitrogen to enter the main combustion furnace;
the waste heat boiler is used for cooling the process gas entering the waste heat boiler and sending the cooled process gas to the primary condenser;
The primary condenser is used for condensing and separating elemental sulfur vapor flowing along with the process gas into liquid sulfur, and sending the liquid sulfur into the liquid sulfur pool;
the primary reheating furnace is provided with a first air inlet and a first fuel gas inlet, wherein the first air inlet is used for enabling air to enter the primary reheating furnace, and the first fuel gas inlet is used for enabling fuel gas to enter the primary reheating furnace;
the secondary reheating furnace is provided with a second air inlet and a second fuel gas inlet, wherein the second air inlet is used for enabling air to enter the secondary reheating furnace, and the second fuel gas inlet is used for enabling fuel gas to enter the secondary reheating furnace;
the tail gas trap comprises a top outlet and a first liquid sulfur outlet; the top outlet is divided into a first branch and a second branch, the first branch is connected with the inlet end of the steam injector, and the second branch is connected with the tail gas treatment unit; the first liquid sulfur outlet is connected with the liquid sulfur tank;
the first-stage condenser, the second-stage condenser, the third-stage condenser and the tail gas catcher are respectively connected with the liquid sulfur pool;
the pressure regulating valve is arranged on the second branch and is used for controlling the back pressure of the shutdown sulfur removal device, wherein the pressure regulating valve is opened when the pressure is high, part of the tail gas enters the tail gas treatment unit through the pressure regulating valve, and the pressure regulating valve is closed when the pressure is low;
The method comprises the following steps:
closing a boundary valve on the sour gas pipeline, stopping sour gas from entering the main combustion furnace, and opening a fuel gas interlocking valve so as to enable fuel gas to enter the main combustion furnace;
heating and mixing fuel gas, air, nitrogen and circulating tail gas in the main combustion furnace to form process gas, wherein the volume flow ratio of the air to the fuel gas is (9-10): 1, the mass flow ratio of the fuel gas to the circulating tail gas is (2-4): 1, the pressure of the fuel gas is 0.3-0.5 MPa, the pressure of nitrogen is 0.5-0.7 MPa, the air pressure is 80-90 kPa, and the circulating tail gas is pressurized to 20-40 kPa by the steam injector; the fuel gas and the oxygen in the air burn and release heat in the main combustion furnace, and the temperature of the main combustion furnace is controlled to be 1050-1150 ℃;
the process gas is cooled to 280-320 ℃ through the waste heat boiler, then cooled to 165-175 ℃ through the primary condenser, the cooled process gas enters the primary reheating furnace and is heated to 280-320 ℃, the heat of the primary reheating furnace is provided by the combustion and heat release of air entering through the first air inlet and fuel gas entering through the first fuel gas inlet, and the volume flow ratio of the air to the fuel gas is (9-10): 1;
The process gas heated by the primary reheating furnace enters the primary claus reactor, the elemental sulfur deposited in the gaps of the catalyst bed layer in the primary claus reactor is vaporized and removed, the elemental sulfur forms elemental sulfur vapor, the elemental sulfur vapor and the process gas enter the secondary condenser to be cooled to 165-175 ℃, and the elemental sulfur vapor is condensed and separated into liquid sulfur and enters the liquid sulfur pool;
the process gas cooled by the secondary condenser enters the secondary reheating furnace to be heated to 280-320 ℃, the heat of the secondary reheating furnace is provided by the combustion heat release of air entering through the second air inlet and fuel gas entering through the second fuel gas inlet, and the volume flow ratio of the air to the fuel gas is (9-10): 1;
the heated process gas enters the secondary claus reactor, the elemental sulfur deposited in the gaps of the catalyst bed layer in the secondary claus reactor is vaporized and removed to form elemental sulfur vapor, the formed elemental sulfur vapor and the process gas enter the tertiary condenser to be cooled to 165-175 ℃, and the elemental sulfur vapor is condensed and separated into liquid sulfur and then enters the liquid sulfur pool;
The process gas cooled by the three-stage condenser and residual elemental sulfur vapor which is not condensed and separated enter the tail gas catcher, the tail gas catcher catches and separates the residual elemental sulfur vapor to form liquid sulfur into the liquid sulfur pool, and the obtained tail gas is discharged from the top outlet of the tail gas catcher;
part of the tail gas enters the steam injector through the first branch, enters the main combustion furnace after being pressurized by the steam injector, and the other part of the tail gas enters the tail gas treatment unit through the second branch;
after being pressurized by the steam injector, a part of the tail gas enters a circulating tail gas pipeline as circulating tail gas, the flow of the circulating tail gas is controlled by an outlet flow regulating valve of the injector, at least a part of the circulating tail gas in the circulating tail gas pipeline enters a temperature regulating steam inlet as temperature regulating steam for reducing the temperature in the main combustion furnace, and the circulating tail gas with redundant flow enters the tail gas treatment unit after being exhausted by an exhaust valve;
the method further comprises the steps of:
when no liquid sulfur flows to the liquid sulfur pool at the bottom of the tail gas catcher, the primary reheating furnace and the secondary reheating furnace are closed, fuel gas of the main combustion furnace continues to burn, when the temperature of catalyst beds in the primary claus reactor and the secondary claus reactor is reduced to 195-200 ℃, the air quantity of the main combustion furnace is slowly increased, so that the excessive oxygen content of the shutdown sulfur removal device is controlled to be 0.5-1%, when the air is excessive, the temperature of the catalyst beds is ensured to be lower than 230 ℃, and if the temperature exceeds 230 ℃, the excessive oxygen supply quantity is reduced, so that the temperature of the catalyst beds is stabilized or reduced; when the temperature of the catalyst bed is stable and the catalyst bed is in a descending trend, the air quantity of the main combustion furnace is gradually increased so that the content of the excessive oxygen is gradually increased, when the temperature of the catalyst bed is reduced to 150-155 ℃, the main combustion furnace is closed, the fuel gas inlet and the temperature-regulating steam inlet of the main combustion furnace are closed, and the sulfur removal process is finished.
2. A shutdown sulfur removal process as defined in claim 1 wherein,
the secondary condenser comprises a second liquid sulfur outlet;
the tertiary condenser comprises a third liquid sulfur outlet;
and the second liquid outlet of the secondary condenser and the third liquid sulfur outlet of the tertiary condenser are respectively connected with the liquid sulfur pool.
3. The shutdown sulfur removal process of claim 1 wherein the primary condenser comprises a fourth liquid sulfur outlet, the fourth liquid sulfur outlet being connected to the liquid sulfur reservoir.
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| CN210973883U (en) * | 2019-08-02 | 2020-07-10 | 中国石油化工股份有限公司 | Sulfur recovery device is blown in circulation |
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| CN114515509A (en) | 2022-05-20 |
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