CN110790227A - Isothermal transformation hydrogen production method and isothermal transformation furnace matched with coal water slurry gasification device - Google Patents
Isothermal transformation hydrogen production method and isothermal transformation furnace matched with coal water slurry gasification device Download PDFInfo
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- C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
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- C01B3/16—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents by reaction of water vapour with carbon monoxide using catalysts
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- C01B2203/0283—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step
- C01B2203/0288—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step containing two CO-shift steps
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Abstract
The invention relates to an isothermal transformation hydrogen production method and an isothermal transformation furnace matched with a coal water slurry gasification device, wherein raw coal gas from the coal water slurry gasification device enters a low-pressure steam generator to recover heat, a byproduct of low-pressure saturated steam is separated out, and the raw coal gas is divided into two strands after being preheated and detoxified; the first strand enters a gas-cooled shift converter for shift reaction, the second strand of raw gas and the primary gas-cooled shift gas after heat recovery converge to form mixed gas, firstly enters a first reaction cavity for medium-temperature shift reaction to generate primary isothermal shift gas and byproduct medium-pressure saturated steam, and then enters a second reaction cavity for low-temperature shift reaction to generate secondary isothermal shift gas and byproduct low-pressure saturated steam; the CO content in the mixed gas is reduced from 20-50 v% to 0.3-0.4 v%, and the hydrogen content is 45-65 v%.
Description
Technical Field
The invention relates to a chemical process and chemical equipment, in particular to an isothermal transformation hydrogen production method and an isothermal transformation furnace matched with a coal water slurry gasification device.
Background
China is a country with abundant coal resources and relatively short petroleum resources, and since the 21 st century, the coal chemical industry of China enters a rapid development stage. Coal gasification is an important method for chemical processing of coal and is a key to realizing clean utilization of coal. The gasification technology using coal water slurry as raw material includes multi-nozzle opposed coal water slurry gasification technology, GE coal water slurry gasification technology and the like. The carbon monoxide content of the crude gas produced by the gasification technology is about 38-50% (V%, dry basis), and the water/dry gas molar ratio is about 1.1-1.7.
The CO conversion process is an indispensable ring in the modern coal chemical technology and plays a role in starting and stopping. The purpose of CO conversion is to react water vapor with CO to generate carbon dioxide and hydrogen to meet the requirements of downstream hydrogen users.
At present, the process flow design of the CO transformation hydrogen production process matched with coal water slurry gasification in China mostly adopts a mode of multi-stage adiabatic reaction and indirect heat energy recovery, and the process has a series of problems of easy over-temperature, long process flow, more equipment, large investment, high energy consumption, large system pressure drop, short service life of a catalyst and the like.
The isothermal transformation process developed in recent years is matched with a CO transformation hydrogen production process flow of water-coal-slurry gasification, and an isothermal + adiabatic transformation process or a double isothermal transformation process is mostly adopted, and only saturated steam can be produced as a byproduct in the process, so that the steam quality is low.
For example, in the 'CO shift unit system matched with a coal water slurry gasification unit' disclosed in the Chinese patent application with the application number of 201020291829.9, the technological process is set as multi-stage adiabatic shift reaction and indirect heat energy recovery, and the process has the disadvantages of long flow, more equipment and large investment.
As disclosed in the chinese invention patent application with application number 201210185731.9, "a water shift heat conversion process for energy-saving deep conversion of by-product high-grade steam", the process flow of the embodiment 1 and the embodiment 2 of the patent is set as follows: the double isothermal shift converter series process and the isothermal and adiabatic shift process can only produce saturated steam.
Disclosure of Invention
The invention aims to solve the technical problem of providing an isothermal transformation hydrogen production method matched with a coal water slurry gasification device aiming at the current situation of the prior art, which can effectively avoid the overtemperature of a gas-cooled reactor and simultaneously produce medium-pressure superheated steam as a byproduct.
The invention aims to solve another technical problem of providing an isothermal shift furnace used in an isothermal shift hydrogen production method matched with a coal water slurry gasification device aiming at the current situation of the prior art, wherein the isothermal shift furnace can simultaneously carry out an intermediate temperature shift reaction and a low temperature shift reaction.
The technical scheme adopted by the invention for solving the technical problems is as follows: an isothermal transformation hydrogen production method matched with a coal water slurry gasification device is characterized by comprising the following steps:
the temperature of the crude gas from the water-coal-slurry gasification device is reduced to 210-245 ℃ after the crude gas enters a low-pressure steam generator to recover heat, and meanwhile, low-pressure saturated steam is byproduct;
feeding the cooled crude gas into a feed separator, feeding the separated condensate into a low-pressure steam superheater to overheat low-pressure saturated steam, reducing the temperature to 200-220 ℃, and sending the steam out of a battery boundary region; the raw gas after the condensate is separated enters a raw gas preheater, is preheated to 220-270 ℃, is subjected to impurity removal by a detoxification tank, and is divided into two strands;
wherein, the first strand of raw gas which accounts for 20-40 v% enters a gas-cooled shift converter for shift reaction to generate primary gas-cooled shift gas; converging a second strand of raw coal gas accounting for 80-60 v% of the total volume and the primary air-cooled conversion gas after heat recovery to form mixed gas, and allowing the mixed gas to enter an isothermal conversion furnace for conversion reaction;
the second strand of crude gas conveying pipeline is provided with a flow control valve for adjusting the proportion of the two strands of crude gas;
the mixed gas firstly enters a first reaction cavity of the isothermal shift converter to carry out medium temperature shift reaction, and primary isothermal shift gas is generated; boiler water in the first steam drum enters a first heat exchange pipe in the first reaction cavity to take reaction heat away, and medium-pressure saturated steam is a byproduct;
the medium-pressure saturated steam returns to the first steam bag liquid separation and is sent to the air-cooled shift converter to be used as a heat taking medium, the medium-pressure saturated steam is superheated to 340-420 ℃, and the medium-pressure superheated steam discharged from the air-cooled shift converter is sent to downstream users;
the primary isothermal shift gas enters a second reaction cavity of the isothermal shift converter to carry out low-temperature shift reaction to generate secondary isothermal shift gas; boiler water in the second steam drum enters a second heat exchange pipe in the second reaction cavity to take reaction heat away, and low-pressure saturated steam is a byproduct;
the byproduct low-pressure saturated steam returns to the second steam drum for liquid separation and then converges with the byproduct low-pressure saturated steam of the low-pressure steam generator, and the byproduct low-pressure saturated steam enter the low-pressure steam superheater and are superheated to 190-240 ℃ by the condensate, so that the obtained low-pressure superheated steam is sent to a downstream user;
the mixed gas is subjected to CO conversion reaction in an isothermal conversion furnace to generate hydrogen, the CO content in the mixed gas is reduced from 20-50% (V%, dry basis) to 0.3-0.4V% (dry basis), and crude hydrogen, namely secondary isothermal conversion gas, with the hydrogen content of about 45-65% (V%, dry basis) and the temperature of 200-230 ℃ is obtained at the outlet of the isothermal conversion furnace.
The crude hydrogen out of the isothermal shift converter sequentially enters a medium-pressure boiler water preheater to preheat medium-pressure boiler water and a low-pressure boiler water preheater to preheat low-pressure boiler water, the preheated medium-pressure boiler water is sent to the first steam drum, and two strands of preheated low-pressure boiler water are respectively sent to the second steam drum and the low-pressure steam generator; the crude hydrogen after heat recovery is sent to the downstream.
Preferably, the water-gas ratio of the raw gas from the water-coal-slurry gasification device is 1.1-1.7, the temperature is 220-250 ℃, and the pressure is 3.5-8.0 MPa (G), the raw gas enters a low-pressure steam generator to exchange heat with water of a low-pressure boiler, the water-gas ratio of the raw gas is adjusted, and low-pressure saturated steam with the pressure of 0.4-1.0 MPa (G) is obtained as a byproduct.
Furthermore, a temperature regulation secondary line can be connected in parallel with the low-pressure steam generator, and a flow control valve is arranged on the temperature regulation secondary line; for adjusting the water-gas ratio of the raw gas exiting the low pressure steam generator. The preheating temperature of the crude gas is adjusted through the flow control valve, and the operation is flexible.
Preferably, the temperature of the medium-pressure superheated steam discharged from the gas-cooled shift converter is 340-420 ℃;
preferably, the temperature of the primary air-cooled conversion gas discharged from the air-cooled conversion furnace is 350-400 ℃, and the temperature of the primary air-cooled conversion gas is reduced to 240-290 ℃ after the primary air-cooled conversion gas exchanges heat with the crude gas.
Preferably, the medium-pressure saturated steam pressure is 3.0-6.0 MPa (G), and the low-pressure saturated steam pressure is 0.4-1.0 MPa (G).
Preferably, the temperature of the secondary isothermal transformation gas is 200-230 ℃, and the dry basis content of CO is 0.3-0.4 v%;
the secondary isothermal shift gas enters the medium-pressure boiler water preheater to heat medium-pressure boiler water at the temperature of 100-110 ℃ to 200-245 ℃, and the medium-pressure boiler water is sent to the first steam drum, and the temperature of the shift gas is reduced to 190-220 ℃; then the steam enters a low-pressure boiler water preheater, the low-pressure boiler water with the temperature of 100-110 ℃ is heated to 130-170 ℃ and then is respectively sent to the second steam drum and the low-pressure steam generator; the temperature of the secondary isothermal shift gas is reduced to 170-210 ℃, and the secondary isothermal shift gas is used as crude hydrogen and sent to the downstream.
The isothermal shift converter is matched with the isothermal shift hydrogen production method of the coal water slurry gasification devices, and is characterized by comprising a furnace body, a catalyst frame arranged in the furnace body and a plurality of heat exchange tubes arranged in the catalyst frame, wherein a synthesis gas collecting pipeline is also arranged in the catalyst frame, and a cavity between the catalyst frame and the synthesis gas collecting pipeline forms a reaction cavity; the method is characterized in that:
the heat exchange tubes are divided into two groups and comprise a first group of heat exchange tubes connected with a first refrigerant source and a second group of heat exchange tubes connected with a second refrigerant source, the first group of heat exchange tubes are arranged close to the catalyst frame, and the second group of heat exchange tubes are arranged close to the synthesis gas collecting pipelines.
Preferably, the first refrigerant source is a first steam drum, and the second refrigerant source is a second steam drum; preferably, the first steam drum produces medium-pressure saturated steam as a byproduct, and the second steam drum produces low-pressure saturated steam as a byproduct;
an inlet of each first heat exchange tube in the first group of heat exchange tubes is connected with a cooling water outlet of a first steam drum, and an outlet of each first heat exchange tube is connected with a steam inlet of the first steam drum;
and the inlet of each second heat exchange tube in the second group of heat exchange tubes is connected with the cooling water outlet of the second steam drum, and the outlet of each second heat exchange tube is connected with the steam inlet of the second steam drum.
As a further improvement of the above scheme, the catalyst frame comprises an inner cylinder and an outer cylinder, the inner cylinder is sleeved in the outer cylinder and has a gap with the outer cylinder, and the gap between the outer cylinder and the side wall of the furnace body forms a feed gas channel; the synthesis gas collecting pipeline is arranged in the inner barrel;
the reaction cavity is divided into a first reaction cavity between the outer cylinder and the inner cylinder and a second reaction cavity between the inner cylinder and the synthesis gas collecting pipeline by the inner cylinder;
the first group of heat exchange tubes are arranged in the first reaction cavity, and at least part of the second group of heat exchange tubes are arranged in the first reaction cavity.
Preferably, a first part of the second group of heat exchange tubes is arranged in the second reaction cavity, and a second part of the second group of heat exchange tubes is arranged in the first reaction cavity, is positioned at the inner side of the first group of heat exchange tubes and is close to the inner barrel.
The catalyst filled in the reaction cavity in each scheme can be one, such as a wide-temperature catalyst; preferably, the first reaction chamber is filled with a first catalyst, and the second reaction chamber is filled with a second catalyst. The first catalyst and the second catalyst are different catalysts.
Preferably, the heat exchange area of the first group of heat exchange tubes accounts for 0.4-0.6 of the total heat exchange area;
the heat exchange area is the external surface area of the heat exchange tube embedded in the catalyst bed layer. The heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes.
The total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.
Preferably, the heat exchange area of the second part of the second group of heat exchange tubes in the first reaction cavity accounts for 0.06-0.2 of the total heat exchange area, so that the temperature of the reaction gas entering the second reaction cavity is about 230 ℃.
The cross sections of the inner cylinder and the outer cylinder are the same as the cross section structures of the corresponding furnace body parts.
Further, a pressure control system for controlling the low-temperature shift reaction depth in the second reaction cavity can be arranged on the second steam drum. The low-variation reaction depth is controlled by adjusting the steam production pressure of the second steam drum, and the dry basis concentration of CO in the outlet conversion gas is ensured to be 0.3-0.4 v%.
The pressure control system is conventional.
Compared with the prior art, the invention has the advantages that:
1) connecting the isothermal shift converter and the gas-cooled shift converter in parallel, dividing the crude gas into two streams, respectively entering the two different shift converters, dividing the crude gas into two streams, further reducing the gas amount entering each shift converter, and further reducing the equipment size of the isothermal shift converter and the gas-cooled shift converter;
2) the gas-cooled shift converter is used for overheating medium-pressure steam which is a byproduct of the isothermal shift converter, so that the quality of the medium-pressure steam is improved, and meanwhile, the reaction heat of the gas-cooled shift converter is removed, so that the overtemperature of the gas-cooled shift converter can be effectively avoided;
3) and medium-pressure superheated steam and low-pressure superheated steam are simultaneously by-produced.
4) The invention discloses an isothermal shift furnace, which integrates low-temperature CO shift reaction and medium-temperature CO shift reaction in a reaction furnace, wherein raw material gas firstly passes through a catalyst outer frame to carry out medium-temperature shift reaction, shift reaction heat is transferred through water of a medium-pressure boiler to produce medium-pressure saturated steam as a byproduct, reaction gas after medium-temperature shift reaction is cooled through water of a low-pressure boiler and then enters a catalyst inner frame to carry out low-temperature shift reaction, the dry basis content of CO is reduced to be less than 0.3-0.4 v%, and low-temperature shift reaction heat is transferred through water of a low-pressure boiler to produce low-pressure saturated steam as a byproduct. The system has short flow, less equipment, low investment and small system pressure drop.
Drawings
FIG. 1 is a process flow diagram of an embodiment of the invention;
FIG. 2 is a longitudinal sectional view of an isothermal shift converter in an embodiment of the present invention;
FIG. 3 is a schematic view of the connection between the isothermal shift converter and two steam drums according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view taken along line A-A of FIG. 2;
fig. 5 is a partially enlarged view of a portion C in fig. 4.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
The structure of the isothermal shift furnace in this embodiment is shown in fig. 2 to 5. The method comprises the following steps:
the furnace body 1 'is of a conventional structure and comprises an upper seal head 11', a lower seal head 12 'and a cylinder body 13' connected between the upper seal head 11 'and the lower seal head 12'. A manhole 14 ' is arranged on the upper sealing head 11 ', a manhole cover is covered on the manhole 14 ', and the feed gas inlet 35 is arranged on the manhole cover.
The catalyst frame is used for filling a catalyst and is arranged in the cylinder body 13', and a reaction cavity is formed by a cavity between the catalyst frame and the synthesis gas collecting pipeline. The catalyst frame in this embodiment includes an inner cylinder 21 and an outer cylinder 22.
The mounting structure of the catalyst frame may be any one of those in the prior art as required. In this embodiment, the upper and lower ends of the catalyst frame are not closed, the upper and lower ends of the catalyst bed in the catalyst frame are filled with refractory balls, the outer cylinder is fixed by the cylinder, and the inner cylinder is supported by the heat exchange tubes on both sides and the first and second tube boxes 51 and 61 on the lower side.
The inner cylinder 21 is sleeved in the outer cylinder 22, a gap is formed between the inner cylinder and the outer cylinder 22, and a feed gas channel 2a is formed by the gap between the outer cylinder and the side wall of the furnace body; the synthesis gas collecting pipeline 3' is sleeved in the inner cylinder 21.
The reaction chamber is divided by the inner cylinder into a first reaction chamber 2b between the outer cylinder and the inner cylinder and a second reaction chamber 2c between the inner cylinder and the synthesis gas collection pipe.
The side walls of the inner cylinder 21 and the outer cylinder 22 are both provided with through holes (not shown in the figure), the through holes not only serve as flow channels of raw material gas and synthesis gas, but also play a role of a gas distributor, so that the raw material gas uniformly enters the first reaction cavity, and primary isothermal transformation gas uniformly enters the second reaction cavity.
In this embodiment, the cross-sectional structures of the cylinder, the inner cylinder, the outer cylinder, and the syngas collection conduit are the same, and are concentrically arranged concentric circular structures.
This example is filled with different narrow temperature type catalysts in the first reaction chamber and the second reaction chamber. The first reaction cavity is filled with a cobalt-molybdenum system medium-temperature shift catalyst, and the second reaction cavity is filled with a cobalt-molybdenum system low-temperature shift catalyst. Different types of catalysts are filled according to respective reaction characteristics, so that the conversion catalyst reaction activity in a specific temperature range is fully utilized, the reaction rate is high, and the CO conversion rate is high. This mode is the preferred mode.
The low temperature shift catalyst and the medium temperature shift catalyst may be any one of those in the prior art as required.
The first reaction cavity and the second reaction cavity can be filled with the same wide-temperature catalyst, and the wide-temperature catalyst needs to simultaneously take the medium-temperature conversion activity and the low-temperature conversion activity into consideration, so that the conversion reaction rate and the CO conversion rate are lower than those of the narrow-temperature catalyst. Meanwhile, the wide-temperature catalyst gives consideration to medium-temperature and low-temperature catalytic activity at the expense of the service life of the catalyst. The use of the wide temperature type catalyst may eliminate the need for an inner cylinder.
The synthesis gas collecting pipeline 3 'is used for collecting the secondary isothermal shift gas and sending the secondary isothermal shift gas out of the furnace body 1' through a synthesis gas conveying pipeline 33, is arranged in the middle of the inner cavity of the catalyst frame and is formed by sequentially and detachably connecting a plurality of sections of cylinder bodies 31, and in the embodiment, the adjacent cylinder bodies 31 are connected through flanges 34; a plurality of air inlets (not shown in the figure) for the secondary isothermal air change to enter the synthesis gas collecting pipeline 3' from the catalyst bed layer are arranged on the side wall of each cylinder 31; a plurality of footsteps 32 are sequentially arranged on the inner side wall of the cylinder 31 at intervals along the axial direction. The end cover is detachably connected to the upper end port of the synthesis gas collecting pipeline 3 ', and is communicated with the inner cavity of the upper end enclosure and the manhole 14 ' after being disassembled, so that maintainers can enter the synthesis gas collecting pipeline 3 '; the lower port of the synthesis gas collection tube 3' is connected to a synthesis gas delivery conduit 33.
The heat exchange tubes are provided with a plurality of heat exchange tubes, are vertically arranged in the catalyst bed layer in a penetrating manner in parallel with the axis of the furnace body 1', and comprise a first group of heat exchange tubes consisting of a plurality of first heat exchange tubes 41 and a second group of heat exchange tubes consisting of a plurality of second heat exchange tubes 42. The first heat exchange tubes 41 and the second heat exchange tubes 42 are arranged at regular intervals on concentric circumferential lines in the reaction chamber.
For the sake of distinction, each second heat exchange tube 42 is indicated by a solid circle and each first heat exchange tube 41 is indicated by a hollow circle in fig. 4.
Wherein, each first heat exchange tube 41 is arranged in the first reaction cavity and close to the outer cylinder. The inlet of each first heat exchange pipe is connected with a first cooling water pipeline 52 through a first pipe box 51, and the first cooling water pipeline 52 is connected with the cooling water outlet of the first steam drum 11; the outlet of each first heat exchange pipe 41 is connected with a first steam pipeline 54 through a first steam collecting device 53, and the first steam pipeline 54 is connected with the steam inlet of the first steam drum 11. The first reaction cavity removes heat through medium-pressure boiler water to obtain a byproduct of medium-pressure saturated steam with the pressure of 4.0Mpa (G), and the saturation temperature is about 252 ℃.
Each second heat exchange tube 42 is divided into two portions, a first portion being disposed in the second reaction chamber and a second portion being disposed in the first reaction chamber and disposed adjacent to the inner tube 21. In the embodiment, 2 layers of second heat exchange tubes 42 are arranged in the first reaction cavity, and 1-5 layers are preferred. The inlet of each second heat exchange pipe 42 is connected with a second cooling water pipe 62 through a second pipe box 61, and the second cooling water pipe 62 is connected with the cooling water outlet of the second steam drum 12; the outlet of each second heat exchange tube 42 is connected to a second steam conduit 64 via a second steam collection device 63, the second steam conduit 64 being connected to the steam inlet of the second drum. The second reaction cavity removes heat through the low-pressure boiler water to produce low-pressure saturated steam with the pressure of 0.45Mpa (G), and the temperature of the saturated steam is 155 +/-1 ℃.
And the second steam drum is provided with a pressure control system for controlling the low-temperature shift reaction depth in the second reaction cavity. The pressure control system in the present embodiment is a conventional technique. The depth of low-temperature shift reaction in the second reaction cavity is controlled by adjusting the operating pressure of the second package, so that the dry basis content of CO in shift gas at the outlet of the isothermal shift converter is ensured to be 0.3-0.4 v%.
In this embodiment, the heat exchange area of the first group of heat exchange tubes accounts for 0.48 of the total heat exchange area; the heat exchange area of the second part of the second group of heat exchange tubes accounts for 0.07 of the total heat exchange area, and the heat exchange area of the first part of the second group of heat exchange tubes arranged in the second reaction cavity accounts for 0.45 of the total heat exchange area.
The heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes in the catalyst bed layer; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes in the catalyst bed layer; the total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.
In order to better link the initial temperature of the primary isothermal shift gas in the first reaction cavity entering the second reaction cavity, a second heat exchange tube for partial temperature reduction, namely the second part of the second group of heat exchange tubes, is arranged in the first reaction cavity, and strong heat exchange is carried out between boiler water with lower temperature (low-pressure boiler water at about 155 ℃) and the high-temperature primary isothermal shift gas, so that the shift gas is reduced by 10-40 ℃, the temperature of the shift gas entering the second reaction cavity is about 230 ℃, and the requirement of low-temperature shift reaction is met.
The first tube box 51 and the second tube box 61 may be in a ring tube structure, or may be in a box structure arranged in an up-and-down overlapping manner, or may be in a tube plate form.
The first steam collecting means 53 and the second steam collecting means 63 may be a loop pipe or a header pipe.
The first steam line 54 and the second steam line 64 are each provided with a first expansion joint 55 and a second expansion joint 65, respectively, for absorbing thermal stresses.
As shown in figure 1, crude gas 1 with the water-gas ratio of 1.67, 246 ℃ and 6.3MPa (G) from a coal water slurry gasification device is cooled by a low-pressure steam generator 2, the temperature is reduced to 235 ℃, low-pressure saturated steam with the pressure of 0.45MPa (G) is produced as a byproduct, the low-pressure steam generator 2 is provided with a temperature adjusting secondary line 3, the adjusting secondary line 3 is provided with a flow control valve, and the water-gas ratio of the crude gas is adjusted by changing the flow. The cooled crude gas enters a feed separator 4, the separated 235 ℃ condensate enters a low-pressure steam superheater 14 to overheat low-pressure steam, and the temperature is reduced to 215 ℃ and is sent out of a boundary region. The crude gas after the condensate is separated enters a crude gas preheater 5 to be preheated to 260 ℃ and then enters a detoxification groove 6, and the crude gas after the impurities such as dust and the like are removed by the detoxification groove 6 is divided into two strands.
Wherein, the first strand of raw gas 7 accounting for about 25 v% enters the gas-cooled shift converter 9 for shift reaction, and the second strand of raw gas 8 accounting for about 75 v% is mixed with the primary gas-cooled shift gas after heat recovery at the outlet of the gas-cooled shift converter 9 and then enters the isothermal shift converter 10 for shift reaction.
A heat exchange tube bundle is arranged in the air-cooled shift converter 9, medium-pressure saturated steam sent out by the first steam drum enters the heat exchange tube bundle to be used as a heat-taking medium, and the medium-pressure saturated steam is superheated to 350 ℃. The primary air-cooled shift gas with 370 ℃ at the outlet of the air-cooled shift converter 9 enters the raw gas preheater 5 to exchange heat with the raw gas, and the temperature is reduced to 267 ℃. Mixed with the second strand of raw gas 8 to form mixed gas, and the mixed gas enters an isothermal shift furnace 10 for shift reaction.
In the embodiment, a flow control valve for adjusting the proportion of two strands of raw gas is arranged on the second strand of raw gas conveying pipeline; the method is used for flexibly adjusting the distribution ratio of two strands of crude gas.
The mixed gas enters a cavity of an upper end socket of the isothermal shift converter through a raw material gas inlet 35 on the isothermal shift converter, descends along a raw material gas channel, uniformly enters a catalyst bed layer of a first reaction chamber through each through hole on an outer cylinder, and carries out medium-temperature CO shift reaction to form primary isothermal shift gas, wherein the reaction temperature of the first reaction chamber is 240-280 ℃. Boiler water in the first steam pocket 11 enters each first heat exchange pipe 41 from the first cooling water pipeline in a natural circulation mode, reaction heat of the catalyst bed layer in the first reaction cavity is taken away, a generated steam-water mixture returns to the first steam pocket through the first steam collecting device and the first steam pipeline for steam-liquid separation, and medium-pressure saturated steam of 4.0Mpa (G) is a byproduct.
In order to better link the initial temperature of the primary isothermal shift gas in the first reaction cavity entering the second reaction cavity, partial heat exchange tubes for cooling are arranged in the first reaction cavity, namely the second part of the second group of heat exchange tubes, and the primary isothermal shift gas is reduced by 10-40 ℃ through strong heat exchange between boiler water with lower temperature (low-pressure boiler water at about 155 ℃) and the primary isothermal shift gas with high temperature, so that the temperature of the primary isothermal shift gas entering the second reaction cavity is about 230 ℃ to meet the requirement of low-temperature shift reaction. The reaction temperature of the second reaction cavity is 200-240 ℃; and the obtained secondary isothermal shift gas enters a synthesis gas collecting pipeline and is sent out of the isothermal conversion furnace. The mixed gas is subjected to CO conversion reaction in the isothermal conversion furnace to generate hydrogen, the CO content in the mixed gas is reduced to 0.3-0.4% (V%, dry basis) from 28% (V%, dry basis), and the crude hydrogen with the hydrogen content of about 54% (V%, dry basis) and the temperature of 220 ℃, namely secondary isothermal conversion gas, is obtained at the outlet of the isothermal conversion furnace.
Boiler water in the second steam drum 12 enters a second heat exchange pipe in a second reaction cavity of the isothermal shift furnace in a natural circulation mode, low-temperature shift reaction heat is taken away, and low-pressure saturated steam of 0.45MPa (G) is a byproduct.
And the byproduct medium-pressure saturated steam of 4.0MPa (G) returns to the first steam drum 11 for liquid separation, then is sent to the gas-cooled shift converter 9 to be used as a heat taking medium for taking away reaction heat, is superheated to 350 ℃, and the superheated medium-pressure steam is sent to downstream users.
And (G) returning the low-pressure saturated steam of 0.45MPa to the second steam drum 12, separating the liquid, mixing the liquid with the low-pressure steam by-produced by the low-pressure steam generator 2, sending the mixture to the low-pressure steam superheater 14 to superheat the mixture to 200 ℃, and sending the superheated low-pressure steam to downstream users.
The temperature of the crude hydrogen at the outlet of the isothermal converter 10 is 220 ℃; the crude hydrogen enters a medium-pressure boiler water preheater 13, medium-pressure boiler water at 104 ℃ is heated to 210 ℃ and sent to a first steam drum 11, and the temperature of the crude hydrogen is reduced to 208 ℃. Then enters a low-pressure boiler water preheater 15, heats the low-pressure boiler water with the temperature of 104 ℃ to 135 ℃, and then is respectively sent into a second steam drum 12 and a low-pressure steam generator 2 in two parts. The temperature of the crude hydrogen is reduced to 206 ℃, and the crude hydrogen is further cooled and separated and then sent to a downstream device.
Claims (15)
1. An isothermal transformation hydrogen production method matched with a coal water slurry gasification device is characterized by comprising the following steps:
the temperature of the crude gas from the water-coal-slurry gasification device is reduced to 210-245 ℃ after the crude gas enters a low-pressure steam generator to recover heat, and meanwhile, low-pressure saturated steam is byproduct;
feeding the cooled crude gas into a feed separator, feeding the separated condensate into a low-pressure steam superheater to overheat low-pressure saturated steam, reducing the temperature to 200-220 ℃, and sending the steam out of a battery boundary region; the crude gas after separating the condensate enters a crude gas preheater, is preheated to 220-270 ℃, is subjected to impurity removal by a detoxification tank and is divided into two strands;
wherein, the first strand of raw gas which accounts for 20-40 v% enters a gas-cooled shift converter for shift reaction to generate primary gas-cooled shift gas; converging a second strand of raw coal gas accounting for 80-60 v% of the total volume and the primary air-cooled conversion gas after heat recovery to form mixed gas, and allowing the mixed gas to enter an isothermal conversion furnace for conversion reaction;
the second strand of crude gas conveying pipeline is provided with a flow control valve for adjusting the proportion of the two strands of crude gas;
the mixed gas firstly enters a first reaction cavity of the isothermal shift converter to carry out medium temperature shift reaction, and primary isothermal shift gas is generated; boiler water in the first steam drum enters a first heat exchange pipe in the first reaction cavity to take reaction heat away, and medium-pressure saturated steam is a byproduct;
the medium-pressure saturated steam returns to the first steam bag liquid separation and is sent to the air-cooled shift converter to be used as a heat taking medium, the medium-pressure saturated steam is superheated to 340-420 ℃, and the medium-pressure superheated steam discharged from the air-cooled shift converter is sent to downstream users;
the primary isothermal shift gas enters a second reaction cavity of the isothermal shift converter to carry out low-temperature shift reaction to generate secondary isothermal shift gas; boiler water in the second steam drum enters a second heat exchange pipe in the second reaction cavity to take reaction heat away, and low-pressure saturated steam is a byproduct;
the byproduct low-pressure saturated steam returns to the second steam drum for liquid separation and then converges with the byproduct low-pressure saturated steam of the low-pressure steam generator, and the byproduct low-pressure saturated steam enter the low-pressure steam superheater and are superheated to 190-240 ℃ by the condensate, so that the obtained low-pressure superheated steam is sent to a downstream user;
the mixed gas is subjected to CO conversion reaction in an isothermal conversion furnace to generate hydrogen, the dry basis content of CO in the mixed gas is reduced from 20-50 v% to 0.3-0.4 v%, and crude hydrogen, namely secondary isothermal conversion gas, with the dry basis content of the hydrogen of 45-65 v% and the temperature of 200-230 ℃ is obtained at the outlet of the isothermal conversion furnace;
the crude hydrogen out of the isothermal shift converter sequentially enters a medium-pressure boiler water preheater to preheat medium-pressure boiler water and a low-pressure boiler water preheater to preheat low-pressure boiler water, the preheated medium-pressure boiler water is sent to the first steam drum, and two strands of preheated low-pressure boiler water are respectively sent to the second steam drum and the low-pressure steam generator; the crude hydrogen after heat recovery is sent to the downstream.
2. The isothermal shift hydrogen production method matched with the coal water slurry gasification device according to claim 1, wherein the ratio of crude gas to water vapor from the coal water slurry gasification device is 1.1-1.7, 220-250 ℃ and 3.5-8.0 MPa (G), the crude gas to water vapor enters a low-pressure steam generator to exchange heat with low-pressure boiler water, the ratio of the crude gas to water vapor is adjusted, and low-pressure saturated steam with 0.4-1.0 MPa (G) is obtained as a byproduct.
3. The isothermal transformation hydrogen production method matched with the coal water slurry gasification device according to claim 2, characterized in that the low-pressure steam generator is connected with a temperature regulation secondary line in parallel, and a flow control valve is arranged on the temperature regulation secondary line; for adjusting the water-gas ratio of the raw gas exiting the low pressure steam generator.
4. The isothermal transformation hydrogen production method matched with the coal water slurry gasification device according to claim 2, wherein the temperature of the medium-pressure superheated steam out of the gas-cooled transformation furnace is 340-420 ℃;
the temperature of the primary air-cooled shift gas discharged from the air-cooled shift furnace is 350-400 ℃, and the temperature of the primary air-cooled shift gas after heat exchange with the crude gas is reduced to 240-290 ℃.
5. The isothermal shift hydrogen production method matched with the coal water slurry gasification device according to any one of claims 1 to 4, wherein the medium-pressure saturated vapor pressure is 3.0-6.0 MPa (G), and the low-pressure saturated vapor pressure is 0.4-1.0 MPa (G).
6. The isothermal transformation hydrogen production method matched with the coal water slurry gasification device according to claim 5, characterized in that the temperature of the secondary isothermal transformation gas is 200-230 ℃, and the dry content of CO is 0.3-0.4 v%;
the secondary isothermal shift gas enters the medium-pressure boiler water preheater to heat medium-pressure boiler water at the temperature of 100-110 ℃ to 200-245 ℃, and the medium-pressure boiler water is sent to the first steam drum, and the temperature of the shift gas is reduced to 190-220 ℃; then the steam enters a low-pressure boiler water preheater, the low-pressure boiler water with the temperature of 100-110 ℃ is heated to 130-170 ℃ and then is respectively sent to the second steam drum and the low-pressure steam generator; the temperature of the secondary isothermal shift gas is reduced to 170-210 ℃, and the secondary isothermal shift gas is used as crude hydrogen and sent to the downstream.
7. The isothermal shift furnace used in the isothermal shift hydrogen production method matched with the coal water slurry gasification device according to any one of claims 1 to 6, is characterized by comprising the following steps:
the reactor comprises a furnace body, a catalyst frame arranged in the furnace body and a plurality of heat exchange tubes arranged in the catalyst frame, wherein a synthesis gas collecting pipeline is also arranged in the catalyst frame, and a cavity between the catalyst frame and the synthesis gas collecting pipeline forms a reaction cavity; a gap between the catalyst frame and the furnace body forms a raw material gas inlet channel;
the heat exchange tubes are divided into two groups and comprise a first group of heat exchange tubes connected with a first refrigerant source and a second group of heat exchange tubes connected with a second refrigerant source, the first group of heat exchange tubes are arranged close to the catalyst frame, and the second group of heat exchange tubes are arranged close to the synthesis gas collecting pipelines.
8. The isothermal conversion furnace of claim 7, wherein the first coolant source is a first drum and the second coolant source is a second drum;
an inlet of each first heat exchange tube in the first group of heat exchange tubes is connected with a cooling water outlet of a first steam drum, and an outlet of each first heat exchange tube is connected with a steam inlet of the first steam drum;
and the inlet of each second heat exchange tube in the second group of heat exchange tubes is connected with the cooling water outlet of the second steam drum, and the outlet of each second heat exchange tube is connected with the steam inlet of the second steam drum.
9. The isothermal shift converter according to claim 8, wherein the catalyst frame comprises an inner cylinder and an outer cylinder, the inner cylinder is sleeved in the outer cylinder and has a gap with the outer cylinder, and the gap between the outer cylinder and the side wall of the converter body forms a feed gas channel; the synthesis gas collecting pipeline is arranged in the inner barrel;
the reaction cavity is divided into a first reaction cavity between the outer cylinder and the inner cylinder and a second reaction cavity between the inner cylinder and the synthesis gas collecting pipeline by the inner cylinder;
the first group of heat exchange tubes are arranged in the first reaction cavity, and at least part of the second group of heat exchange tubes are arranged in the first reaction cavity.
10. The isothermal shift furnace of claim 9, wherein a first portion of the second set of heat exchange tubes is disposed within the second reaction chamber and a second portion is disposed within the first reaction chamber and inside the first set of heat exchange tubes and adjacent to the inner barrel.
11. The isothermal shift furnace of claim 10, wherein the first reaction chamber is filled with a first catalyst and the second reaction chamber is filled with a second catalyst.
12. The isothermal shift furnace of claim 11, wherein the first catalyst and the second catalyst are different catalysts.
13. The isothermal shift converter according to any one of claims 7 to 12, wherein the heat exchange area of the first group of heat exchange tubes accounts for 0.4 to 0.6 of the total heat exchange area;
the heat exchange area of the first group of heat exchange tubes is the sum of the external surface areas of the first heat exchange tubes; the heat exchange area of the second group of heat exchange tubes is the sum of the external surface areas of the second heat exchange tubes;
the total heat exchange area is the sum of the heat exchange area of the first group of heat exchange tubes and the heat exchange area of the second group of heat exchange tubes.
14. The isothermal converter according to claim 13, wherein the heat exchange area of the second portion of the second group of heat exchange tubes in the first reaction chamber is 0.06-0.2 of the total heat exchange area.
15. The isothermal shift furnace of claim 14, wherein the second steam drum is provided with a pressure control system for controlling a depth of the low temperature shift reaction in the second reaction chamber.
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