CN114836249A - Coke oven gas methanation feeding method - Google Patents
Coke oven gas methanation feeding method Download PDFInfo
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- CN114836249A CN114836249A CN202210385657.9A CN202210385657A CN114836249A CN 114836249 A CN114836249 A CN 114836249A CN 202210385657 A CN202210385657 A CN 202210385657A CN 114836249 A CN114836249 A CN 114836249A
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- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000000571 coke Substances 0.000 title claims abstract description 16
- 239000007789 gas Substances 0.000 claims abstract description 146
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 96
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 57
- 238000010438 heat treatment Methods 0.000 claims abstract description 27
- 238000004821 distillation Methods 0.000 claims abstract description 8
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 239000000047 product Substances 0.000 claims description 67
- 238000001816 cooling Methods 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 229920006395 saturated elastomer Polymers 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- 239000002994 raw material Substances 0.000 claims description 9
- 239000002918 waste heat Substances 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 6
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 3
- 239000006227 byproduct Substances 0.000 claims description 3
- 238000006477 desulfuration reaction Methods 0.000 claims description 3
- 230000023556 desulfurization Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 239000011593 sulfur Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 20
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 18
- 238000010992 reflux Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000012840 feeding operation Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K3/00—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide
- C10K3/06—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide by mixing with gases
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
- C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
- C10L3/08—Production of synthetic natural gas
-
- 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)
- Oil, Petroleum & Natural Gas (AREA)
- Combustion & Propulsion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of LNG production, in particular to a coke oven gas methanation feeding method, which is characterized in that main methanation and final methanation are simultaneously fed after being heated by nitrogen of a start-up fan, the nitrogen heating process is poured out of the start-up fan, after gas distribution is completed, main methanation and final methanation are simultaneously fed, an ejector, self-produced steam and an ammonia distillation system are merged into a system while the temperature of a methanation system and the pressure of a steam drum are increased, and after feeding is completed, all process indexes quickly meet requirements, so that the time for single feeding of final methanation is saved by 2 hours, and the cost consumption is reduced.
Description
Technical Field
The invention relates to the technical field of LNG production, in particular to a coke oven gas methanation feeding method.
Background
In the LNG methanation start-up feeding process, the temperature of the first-stage methanation bed layer nitrogen is heated to 350-class 330 ℃, the temperature of the second-stage methanation bed layer nitrogen is heated to 320-class 300 ℃, the temperature of the third-stage methanation bed layer nitrogen is heated to 250-class 240 ℃, and the main reactor (the first-stage methanation reactor, the second-stage methanation reactor) and the final methanation (the third-stage methanation reactor) are separately fed. Firstly, switching a temperature rise process of a start-up fan to a final methanation cycle for heat preservation, distributing raw gas and pipe network steam before feeding a main methane (using time is 1 hour), feeding the main methanation, and raising the temperature of a main methane bed from 350 ℃ to 560 ℃ (using time is 7 hours) at a temperature rise rate of 30 ℃/h. The pressure of the steam drum and the condensate level meet the process indexes, the ejector is used and cuts off the steam of the pipe network, the heater and the supplementary heater are switched into self-produced steam, and the heating process cuts off the fan of the system to stop working (2 hours when the system is used) and then the material is fed into the final methanation. And after the first condensation is carried out, the air is discharged to the second condensation, the air is discharged, then an ammonia distillation system is put into the system to adjust the ammonia content at the trimethyl outlet, and the ammonia is sent to a liquefaction section (the time for use is 2 hours) after the test indexes are qualified. In the step-by-step feeding operation of main methanation and final methanation, the system pressure, the flow, the bed layer temperature and the liquid level of a separator fluctuate repeatedly, the process control operation is frequent, the on-site labor amount is large, the feeding time is long, and the cost consumption is large.
Disclosure of Invention
Aiming at the problems of long methanation feeding time, high cost and the like in the prior art, the invention provides the methanation feeding method of the coke oven gas, which shortens the feeding time, reduces the energy consumption and the labor intensity, enables the final methanation outlet gas index to quickly reach the qualified standard and reduces the production cost.
The invention provides a methanation feeding method of coke oven gas, which comprises the following steps:
(1) starting a start-up fan, and circularly heating the primary methanation reactor, the secondary methanation reactor and the tertiary methanation reactor;
(2) the raw material gas and the steam are distributed to form mixed gas, the mixed gas is heated and then enters a first-stage methanation reactor to react, the product gas A is obtained after the reaction and is cooled, and the product gas A is divided into a first strand of product gas A 1 And a second product gas A 2 (ii) a The first stream of product gas A 1 The reaction is carried out in a secondary methanation reactor to obtain a product gas B after the reaction, and the product gas B is subjected to gradient cooling and condensation separation to obtain a product gas C and a condensate A;
(3) heating the product gas C, then reacting in a three-stage methanation reactor to obtain a product gas D, cooling the product gas D, and then condensing and separating to obtain a product gas E and a condensate B;
(4) mixing the condensate A and the condensate B, heating and sending the mixture to an ammonia still for steam stripping and ammonia distillation, continuously cooling and reusing the condensate at the bottom of the ammonia still after heat exchange with the mixed solution of the condensate A and the condensate B, and performing gas-liquid separation after cooling tail gas at the top of the ammonia still to obtain ammonia-rich gas and ammonia-rich liquid for reuse;
(5) leading-in waste heat boiler byproduct middling pressure steam of one-level methanation reactor reaction waste heat, middling pressure steam gets into the steam drum and produces saturated middling pressure steam, and saturated middling pressure steam heating becomes overheated middling pressure steam, and overheated middling pressure steam divide into first strand of overheated middling pressure steam and the overheated middling pressure steam of second strand, and the mixed gas in step (2) is spouted into through the sprayer to first strand of overheated middling pressure steam, and the overheated middling pressure steam of second strand merges into the steam pipe network.
Further, in the step (1), the first-stage methanation reactor, the second-stage methanation reactor and the third-stage methanation reactor are arranged on the circulating pipeline, and the circulating pipeline is provided with a heating device and a start-up fan.
Further, in the step (1), the inlet temperature of the primary methanation reactor is 350 ℃, and the outlet temperature is 330 ℃; the inlet temperature of the secondary methanation reactor is 320 ℃, and the outlet temperature is 300 ℃; the inlet temperature and the outlet temperature of the three-stage methanation reactor are 250 ℃ and 240 ℃.
Further, in the step (2), the method for distributing the gas between the raw material gas and the steam comprises the following steps: the raw material gas is desulfurized, the total sulfur after desulfurization is less than or equal to 20ppb, and the flow rate is 2500Nm 3 H, steam flow rate of 7500kg/h, and mixed gas pressure control of 0.6 MPaG.
Further, in the step (2), the gradient cooling method of the product gas B comprises the steps of sequentially passing through a steam superheater, a feeding preheater, a boiler feed water preheater, a tower kettle reboiler, a desalted water preheater and a process cooler.
Furthermore, the temperature of the mixed gas entering the first-stage methanation reactor is 320-330 ℃, and the temperature of the product gas C entering the third-stage methanation reactor is 250 ℃.
Further, the method for heating the product gas C in the step (3) is that the product gas C is sequentially heated by a material flow heat exchanger and a supplementary heater.
Further, in the step (4), the ammonia content of the condensate at the bottom of the ammonia distillation tower is less than 5 mg/L; cooling the condensate after heat exchange to be used as ammonia washing water of a separation tank, or sending the condensate to a boundary region for reuse; the ammonia-rich gas and the ammonia-rich liquid are sent to a battery limits for reuse.
Further, in the step (5), the operation pressure of the steam drum is 4-4.5 MPaG, and the steam production of the steam drum is 3 t/h.
The method has the beneficial effects that the main methanation and the final methanation are simultaneously fed after the temperature rise of the nitrogen of the start-up fan is finished. And (3) pouring out the start-stop fan in the nitrogen heating process, feeding the main methane and the final methane at the same time after the gas distribution is finished, and merging the ejector, the self-produced steam and the ammonia distillation system into the system while increasing the temperature of the methanation system and the pressure of a steam drum. After the feeding is finished, all process indexes can quickly meet the requirements, the final independent methanation feeding time is saved by 2 hours, and the cost and the consumption are reduced.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a nitrogen circulation heating process of a main methane start-up fan and a final methane start-up fan in the embodiment of the invention.
FIG. 2 is a schematic diagram of the simultaneous feeding flow of main methanation and final methanation in the embodiment of the invention.
FIG. 3 is a schematic view of a process for producing ammonia while feeding in accordance with an embodiment of the present invention.
In the figure: 101-start-up fan, 102-electric furnace, 103-steam superheater A, 104-first material inlet and outlet heat exchanger, 105-supplementary heater, 106-second material inlet and outlet heat exchanger;
1-mixed gas, 2-double-block stop valve A 1 3-double-block stop valve A 2 4-feeding preheater, 5-heating mixed gas A, 6-heating mixed gas B, 7-starting electric heater, 8-heating mixed gas C, 9-first-stage methanation reactor, 10-first product gas, 11-waste heat boiler, 12-product gas A, 13-first product gas A 1 14-second product gas A 2 15-second-stage methane reactor, 16-product gas B, 17-steam superheater B, 18-heat exchange gas A, 19-heat exchange gas B, 20-boiler feed water preheater, 21-heat exchange gas C, 22-tower reboiler, 23-heat exchange gas D, 24-desalted water preheater, 25-heat exchange gas E, 26-process cooler, 27-heat exchange gas F, 28-first-stage condensate separation tank, 29-product gas C, 30-condensate A, 31-pressure regulating valve, 32-double-barrier stop valve B 1 33-double-block stop valve B 2 34-stream heat exchanger, 35-second product gas, 36-supplemental heater, 37-third product gas, 38-three-stage methanation reactor, 39-product gas D, 41-product cooler, 42-fourth product gas, 43-secondary condensate knockout drum, 44-product gas E, 45-condensate B, 46-regulating valve A, 47-regulating valve B, 48-mixed condensate A, 49-ammonia still feeding preheating50-mixed condensate B, 51-ammonia still, 52-ammonia-rich tail gas A, 53-clean condensate;
60-tower kettle cooler, 61-first strand condensate, 62-second strand condensate, 63-ammonia washing pump, 64-condensate pump, 65-ammonia still tower top cooler, 66-ammonia-rich tail gas B, 67-ammonia still tower reflux tank, 68-ammonia-rich liquid and 69-ammonia-rich gas;
80-steam drum, 81-saturated medium pressure steam, 82-first saturated medium pressure steam, 83-second saturated medium pressure steam, 84-superheated medium pressure steam, 85-first superheated medium pressure steam, 86-second superheated medium pressure steam, and 87-mixed product gas.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The invention relates to a methanation feeding method of coke oven gas, which comprises the following steps:
(1) as shown in fig. 1, a start-up fan 101 is started to circularly heat a first-stage methanation reactor 9, a second-stage methanation reactor 15 and a third-stage methanation reactor 38, the first-stage methanation reactor 9, the second-stage methanation reactor 15 and the third-stage methanation reactor 38 are arranged on a circulating pipeline, the circulating pipeline comprises a pipeline a, a pipeline b and a pipeline d, a heating device and the start-up fan 101 are arranged on the circulating pipeline, the heating device comprises an electric furnace 102, a steam superheater a103, a first material feeding and discharging heat exchanger 104, a supplementary heater 105 and a second material feeding and discharging heat exchanger 106, the inlet temperature of the subsequent first-stage methanation reactor 9 is 350 ℃, and the outlet temperature of the subsequent first-stage methanation reactor is 330 ℃; the inlet temperature of the secondary methanation reactor 15 is 320 ℃, and the outlet temperature is 300 ℃; the inlet temperature of the three-stage methanation reactor 38 is 250 ℃, the outlet temperature is 240 ℃, the hand valve of the reflux pipeline c is closed after the temperature is raised, the pressure of the start-up fan 101 is reduced to be below 0.5MPaG, the operation time of the final methanation cycle heat preservation valve is saved through the operation, and the operation time and the process adjustment time of the valve are saved by 30 minutes;
(2) referring to fig. 2, the gas distribution of the raw material gas and the steam forms a mixed gas 1, and the gas distribution method of the raw material gas and the steam comprises the following steps: the raw material gas is desulfurized, the total sulfur after desulfurization is less than or equal to 20ppb, and the flow rate is 2500Nm 3 And h, the steam flow rate is 7500kg/h, the pressure of the mixed gas 1 is controlled to be 0.6MPaG, and the gas distribution is finished. The mixed gas 1 passes through a double-blocking stop valve A 1 2. Double-blocking stop valve A 2 3, heating to 310-320 ℃ by a feed preheater 4, heating the heated mixed gas 1 to 320-330 ℃ by a start-up electric heater 7, reacting the heated gas in a primary methanation reactor 9, heating from 350 ℃ to 560 ℃ at a heating rate of 30 ℃/h according to the bed temperature of the primary methanation reactor 9 to obtain a first product gas 10, introducing the first product gas into a waste heat boiler 11, cooling to 345 ℃ required by the inlet temperature of a secondary methanation reactor 15, cooling to obtain a product gas A12, and dividing the product gas A12 into a first product gas A 1 13 and a second product gas A 2 14, the first stream of product gas A 1 13, carrying out reaction in a secondary methanation reactor 15 to obtain a product gas B16 with the temperature of 350-370 ℃, sequentially passing the product gas B16 through a steam superheater B17, a heat exchange gas A18, a feed preheater 4, a heat exchange gas B19, a boiler feed water preheater 20, a heat exchange gas C21, a tower kettle reboiler 22, a heat exchange gas D23, a desalted water preheater 24, a heat exchange gas E25, a process cooler 26 and a heat exchange gas F27 to carry out step cooling to 60-70 ℃, and finally introducing into a primary condensate separating tank 28 to carry out separation to obtain a product gas C29 and a condensate A30 with the temperature of 60-70 ℃, wherein a pressure regulating valve 31 is arranged at an outlet at the upper end of the primary condensate separating tank 28;
(3) the product gas C29 passes through a double-blocking stop valve B 1 32. Double-blocking stop valve B 2 33. Heating the material flow heat exchanger 34 to obtain a second product gas 35 at 210-220 ℃, introducing a supplementary heater 36, heating to obtain a third product gas 37 at 250 ℃, introducing the third product gas 37 into a three-stage methanation reactor 38 for reaction to obtain a product gas D39 at 250 ℃, introducing the product gas D39 into the material flow heat exchanger 34 and the product cooler 41 for cooling to obtain a cooling liquidIntroducing the warmed fourth product gas 42 into a secondary condensate separation tank 43 for separation to obtain a product gas E44 and a condensate B45 at the temperature of 30-40 ℃, wherein the pressure and the flow of the product gas E44 are controlled by an adjusting valve A46 and an adjusting valve B47; in the step, the main methanation and the final methanation are simultaneously fed, so that the step of emptying and feeding the main methanation through the outlet of the first-stage condensate separating tank 28 is saved, the main methanation directly enters the third-stage methanation reactor 38 and is emptied and fed through the outlet of the second-stage condensate separating tank 43, and the operation time of the single feeding of the final methanation is shortened by 1 hour;
(4) as shown in figure 3, the condensate A30 and the condensate B45 are mixed to obtain a mixed condensate A48, the mixed condensate A48 enters an ammonia still feeding preheater 49, the mixed condensate B50 heated to 100 ℃ is sent to an ammonia still 51 for stripping and ammonia distillation, and the content of the condensate ammonia is less than 5 mg/L. The clean condensate 53 at the bottom of the ammonia still 51 and at 130 ℃ is subjected to heat exchange with the mixed condensate A48 through the ammonia still feeding preheater 49 to obtain the mixed condensate C at 80 ℃, and is cooled to 30 ℃ after entering the tower kettle cooler 60, and is divided into a first strand of condensate 61 and a second strand of condensate 62, wherein the first strand of condensate 61 is reversely supplied to the second-stage condensate separating tank 43 by the ammonia washing pump 63 and is reused as ammonia washing water (condensate is reused, resource waste is reduced), so that the ammonia content at the methanation outlet meets the process requirements in the feeding process. And the surplus second condensate 62 is sent to a boundary area through a condensate pump 64, and the 40% automatic feeding of the liquid level of the ammonia still is controlled through a regulating valve. And introducing the ammonia-rich tail gas A52 with the temperature of 130 ℃ at the tower top into an ammonia still tower top cooler 65 to be cooled to obtain the ammonia-rich tail gas B66 with the temperature of 50 ℃, and introducing the ammonia-rich tail gas B66 into an ammonia still tower reflux tank 67 to carry out gas-liquid separation to obtain ammonia-rich gas 69 and ammonia-rich liquid 68 which are sent to a battery limit. The step saves the time of washing ammonia for 30 minutes by using an ammonia still as a secondary condensate separating tank after the final methanation is finished by single feeding;
(5) as shown in fig. 2, in the methanation reaction, the bed temperature of the primary methanation reactor 9 is gradually increased from 350 ℃ to 560 ℃, the byproduct medium-pressure steam of the waste heat boiler 11 by using the reaction waste heat enters a steam drum 80 to produce saturated medium-pressure steam 81, the saturated medium-pressure steam is divided into a first saturated medium-pressure steam 82 and a second saturated medium-pressure steam 83, the first saturated medium-pressure steam 82 is introduced into a steam superheater 17 to be heated to become superheated medium-pressure steam 84, and the superheated medium-pressure steam 84 is divided into a first superheated medium-pressure steam 85 and a second superheated medium-pressure steam 86 to be externally connected to the grid. The steam production of the steam pocket 80 reaches 3t/h, the operating pressure of the steam pocket is close to the normal operating value of 4-4.5 MPaG, the pipeline is heated through an on-site hand valve, the mixed product gas 87 obtained by using an ejector is mixed with the heated mixed gas A5 to obtain the heated mixed gas B6, the heated mixed gas enters the start-up electric heater 7 and is heated to 320-330 ℃, the heated mixed gas C8 is introduced into the primary methanation reactor 9 to control the reaction temperature, and the start-up steam of 7500kg/h exits through slowly increasing the mixed product gas 87. And closing the steam of the pipe network of the start-up heater 7 and the supplementary heater 105, and introducing a second strand of saturated medium-pressure steam 83 to provide a heat source for the heat exchanger. The second stream of superheated medium pressure steam 86 is sent to the pipe network steam on a production basis. The pipe network steam is switched into the self-produced steam in the feeding process, the feeding time is fully utilized, and the working efficiency is improved.
The embodiment realizes that the main methanation and the final methanation are simultaneously fed after the nitrogen temperature rise of the start-up fan is finished. And (3) pouring out the start-stop fan in the nitrogen heating process, feeding the main methane and the final methane simultaneously after the gas distribution is finished, and merging the ejector, the self-produced steam system and the ammonia distillation system into the system while increasing the temperature of the methanation system and the pressure of a steam drum. After the feeding is finished, all process indexes can quickly meet the requirements, the final independent methanation feeding time is saved by 2 hours, and the cost and the consumption are reduced.
Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention.
Claims (9)
1. The methanation feeding method of the coke oven gas is characterized by comprising the following steps:
(1) starting a start-up fan, and circularly heating the primary methanation reactor, the secondary methanation reactor and the tertiary methanation reactor;
(2) the raw material gas and the steam are distributed to form mixed gas, the mixed gas is heated and then enters a first-stage methanation reactor to react, the product gas A is obtained after the reaction and is cooled, and the product gas A is divided into a first strand of product gas A 1 And a second product gas A 2 (ii) a The first stream of product gas A 1 The reaction is carried out in a secondary methanation reactor to obtain a product gas B after the reaction, and the product gas B is subjected to gradient cooling and condensation separation to obtain a product gas C and a condensate A;
(3) heating the product gas C, then reacting in a three-stage methanation reactor to obtain a product gas D, cooling the product gas D, and then condensing and separating to obtain a product gas E and a condensate B;
(4) mixing the condensate A and the condensate B, heating and sending the mixture to an ammonia still for steam stripping and ammonia distillation, continuously cooling and reusing the condensate at the bottom of the ammonia still after heat exchange with the mixed solution of the condensate A and the condensate B, and performing gas-liquid separation after cooling tail gas at the top of the ammonia still to obtain ammonia-rich gas and ammonia-rich liquid for reuse;
(5) leading-in waste heat boiler byproduct middling pressure steam of one-level methanation reactor reaction waste heat, middling pressure steam gets into the steam drum and produces saturated middling pressure steam, and saturated middling pressure steam heating becomes overheated middling pressure steam, and overheated middling pressure steam divide into first strand of overheated middling pressure steam and the overheated middling pressure steam of second strand, and the mixed gas in step (2) is spouted into through the sprayer to first strand of overheated middling pressure steam, and the overheated middling pressure steam of second strand merges into the steam pipe network.
2. The coke oven gas methanation feeding method of claim 1, wherein in step (1), the first-stage methanation reactor, the second-stage methanation reactor and the third-stage methanation reactor are arranged on a circulating pipeline, and a heating device and a start-up fan are arranged on the circulating pipeline.
3. The coke oven gas methanation feed method of claim 1 or 2, characterized in that, in step (1), the inlet temperature of the primary methanation reactor is 350 ℃, and the outlet temperature is 330 ℃; the inlet temperature of the secondary methanation reactor is 320 ℃, and the outlet temperature is 300 ℃; the inlet temperature and the outlet temperature of the three-stage methanation reactor are 250 ℃ and 240 ℃.
4. The coke oven gas methanation feeding method of claim 1, wherein in the step (2), the gas distribution method of the raw material gas and the steam comprises the following steps: the raw material gas is desulfurized, the total sulfur after desulfurization is less than or equal to 20ppb, and the flow rate is 2500Nm 3 The steam flow rate was 7500kg/h, and the mixture pressure was controlled to 0.6 MPaG.
5. The coke oven gas methanation feeding method of claim 1, wherein in the step (2), the product gas B is subjected to gradient temperature reduction by sequentially passing through a steam superheater, a feed preheater, a boiler feed water preheater, a tower reboiler, a desalted water preheater and a process cooler.
6. The coke oven gas methanation feeding method of claim 1, wherein the temperature of the mixed gas entering the first-stage methanation reactor is 320-330 ℃, and the temperature of the product gas C entering the third-stage methanation reactor is 250 ℃.
7. The coke oven gas methanation feeding method of claim 1, wherein the product gas C in the step (3) is heated by sequentially passing the product gas C through a material flow heat exchanger and a supplementary heater.
8. The coke oven gas methanation feed method as set forth in claim 1, wherein in step (4), the ammonia content in the bottom condensate of the ammonia still is less than 5 mg/L; cooling the condensate after heat exchange to be used as ammonia washing water of a separation tank, or sending the condensate to a boundary region for reuse; the ammonia-rich gas and the ammonia-rich liquid are sent to a battery limits for reuse.
9. The coke oven gas methanation feeding method of claim 1, wherein in the step (5), the operation pressure of a steam drum is 4-4.5 MPaG, and the steam production of the steam drum is 3 t/h.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210385657.9A CN114836249A (en) | 2022-04-13 | 2022-04-13 | Coke oven gas methanation feeding method |
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