CN112125779A - Two-stage double-separation methanol production method - Google Patents

Two-stage double-separation methanol production method Download PDF

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CN112125779A
CN112125779A CN202010892255.9A CN202010892255A CN112125779A CN 112125779 A CN112125779 A CN 112125779A CN 202010892255 A CN202010892255 A CN 202010892255A CN 112125779 A CN112125779 A CN 112125779A
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卢健
王雪林
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Nanjing Jutuo Chemical Technology Co ltd
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Nanjing Jutuo Chemical Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/152—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases characterised by the reactor used
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • 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
    • 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
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

The invention discloses a two-stage double-separation methanol production method, which comprises the following steps: (1) compressing a second mixed gas containing a second make-up gas and a second lean gas by a circulator, then feeding the second mixed gas into a first reactor for reaction, and discharging a first tower gas; (2) after methanol is recovered from the first tower gas, a first lean gas is formed; (3) mixing the first lean gas and the first make-up gas to form a first mixed gas, allowing the first mixed gas to enter a second reactor for reaction, and discharging a second tower outlet gas; (4) after methanol is recovered from the second tower gas, a second lean gas is formed; the first tower outlet gas heats the second mixed gas through a first heat exchanger; the second tower outlet gas heats the first mixed gas through a second heat exchanger. In this application, the material circulative flow between two reactors for the volume ratio of first make-up gas and second make-up gas is roughly the same, and the reaction parameter of two reactors is also roughly the same, can adopt the same mode to control the reaction of two reactors, has increased the stability of production.

Description

Two-stage double-separation methanol production method
Technical Field
The invention relates to a two-stage double-separation methanol production method.
Background
Methanol synthesis usually uses synthesis gas and hydrogen as raw materials to synthesize, then reaction mixed gas discharged from a reactor passes through a gas-liquid separator to separate condensed methanol, unreacted gas separated by the gas-liquid separator is returned to the reactor to continue reaction, and fresh synthesis gas called make-up gas is supplemented to a reaction system to continue reaction, in the production process, in order to improve reaction efficiency, a multistage reactor is generally adopted, and fresh synthesis gas is continuously supplemented to a first-stage reactor, a last-stage reactor is generally carried out in a self-circulation mode, in the reaction system, reactors with different gas concentrations need to be arranged, the types of the reactors are increased, not only the maintenance cost of the reactors is increased, but also different control modes and control points need to be adopted due to the reactors with different forms, the difficulty of production stability is also increased.
Disclosure of Invention
In order to solve the problems, the invention provides a two-stage double-separation methanol production method, which comprises the following steps:
(1) compressing a second mixed gas containing a second make-up gas and a second lean gas by a circulator, then feeding the second mixed gas into a first reactor for reaction, and discharging a first tower outlet gas from the first reactor;
(2) after methanol is recovered from the first tower gas, a first lean gas is formed;
(3) mixing the first lean gas and the first make-up gas to form a first mixed gas, allowing the first mixed gas to enter a second reactor for reaction, and discharging a second tower gas from the second reactor;
(4) after methanol is recovered from the second tower gas, a second lean gas is formed;
the first tower outlet gas heats the second mixed gas through a first heat exchanger;
the second tower outlet gas heats the first mixed gas through a second heat exchanger.
The method is used for a large methanol production device, and the monomer productivity is more than 200 ten thousand tons/year. In this application, it all is provided with a knockout drum to go out tower gas corresponding to first tower gas and second to make first tower gas and second go out tower gas can carry out gas-liquid separation alone, retrieve methyl alcohol. Preferably, the first reactor and the second reactor are identical in structure and size, i.e., the first reactor and the second reactor are two reactors of the same type.
In this application, first make-up gas and second make-up gas are fresh feed gas, namely in this application, divide feed gas to inject into the system twice, the material in the system is under the promotion of circulator, circulation flow between first reactor and second reactor, and supply feed gas in first reactor and second reaction in proper order, because the material is in first reactor and second reactor circulation flow, make the volume ratio of first make-up gas and second make-up gas roughly the same, the reaction parameter of first reactor and second reactor is also roughly the same, can adopt the same mode to control the reaction of two reactors from this, increased the stability of production.
Further, the standard volume ratio of the first lean gas to the first make-up gas is (2-3): 1; the standard volume ratio of the second lean gas to the second make-up gas is (2-3): 1, further preferably, the standard volume ratio of the first lean gas to the first make-up gas is (2.4-2.6): 1; the standard volume ratio of the second lean gas to the second make-up gas is (2.4-2.6): 1. further, the ratio of the standard volume of the first make-up gas to the second make-up gas is 1:1, the standard volume being the volume of the gas at 273.15K and one standard atmosphere.
Under the standard volume ratio, the ratio of hydrogen to carbon monoxide in the first reactor and the second reactor can reach the optimal ratio, the raw material gas supplemented into the system and the reacted gas can reach the basic balance, and the higher production efficiency can be maintained.
Further, in the first make-up gas and the second make-up gas, (H)2-CO2) With (CO + CO)2) The mole ratio of (A) is 2.2-2.3, and the mole percentage of carbon dioxide is 2-3%. Wherein (H)2-CO2) Represents the difference between the moles of hydrogen and carbon dioxide, (CO + CO)2) Represents the sum of the moles of carbon monoxide and carbon dioxide. (H)2-CO2) With (CO + CO)2) The molar ratio of (A) is the hydrogen-carbon ratio, the theoretical value of the hydrogen-carbon ratio is 2.0, and because the main component of the methanol catalyst is copper-based, the catalyst generally comprises an active component Cu and a carrierThe methanol catalyst is sensitive to carbon-to-hydrogen ratio, the conversion rate is improved when the hydrogen-to-carbon ratio is low, but byproducts are increased, the conversion rate is reduced when the hydrogen-to-carbon ratio is high, but the byproducts are reduced. By using the method, the conversion per pass is high, and the production rate of byproducts is 0.2%.
Further, of the first make-up gas and the second make-up gas, H2The total molar ratio of S to COS is less than or equal to 0.1 ppm. The methanol catalyst is sensitive to sulfur, chlorine and other poisons, and H is added to reduce the influence of toxic components on the activity of the catalyst2The total molar ratio of S and COS is now below 0.1 ppm.
Specifically, the inlet temperature of the second mixed gas in the first reactor is 210-240 ℃, the outlet temperature of the first tower gas is 245-250 ℃, and the reaction pressure of the first reactor is 7.5-8.5 MPaG; the inlet temperature of the first mixed gas in the second reactor is 210-240 ℃, the outlet temperature of the second tower outlet gas is 230-240 ℃, and the reaction pressure of the second reactor is 7.5-8.5 MPaG.
The methanol reaction is a reaction with reduced volume, is favorable for being carried out towards the direction of synthesizing methanol under high pressure, but the overhigh pressure can cause higher power cost, but the low pressure is more favorable for reducing comprehensive energy consumption, so that the reaction pressure of 5.0-6.0 MPa is mainly used in small and medium-sized devices, the device in the application is a large-scale methanol production device, the production capacity of a single reactor is more than 100 ten thousand tons per year, and in order to ensure that the whole system can smoothly run, the reaction pressure is increased to 7.5-8.5MPa, so that the application has higher comprehensive cost.
The methanol synthesis reaction is a reversible reaction, the conversion rate of methanol has a certain relation with pressure, temperature and hydrogen-carbon ratio, the reaction temperature area of the catalyst is narrow, particularly for copper-based methanol catalysts, the copper-based methanol catalyst is slightly over-temperature, so that the active crystal grains of the catalyst are easy to enlarge or the catalyst is easy to sinter, and the activity of the catalyst is quickly reduced.
The first reactor is closer to the circulator than the second reactor, and has a higher inlet pressure, so that the outlet temperature of the first reactor is slightly higher than that of the second reactor to fully utilize the high pressure of the gas.
Specifically, in order to smoothly recover the methanol, the temperature of the first tower gas is reduced to 120-130 ℃ after passing through a first heat exchanger, then the temperature is reduced to 60 ℃ through a first air cooler, and finally the temperature is reduced to 40 ℃ through a first water cooler;
the temperature of the second tower outlet gas is reduced to 90-110 ℃ after passing through a second heat exchanger, then the temperature is reduced to 60 ℃ by a second air cooler, and finally the temperature is reduced to 40 ℃ by a second water cooler.
After adopting first heat exchanger and second heat exchanger, can retrieve partial heat energy, return to the system in, nevertheless go out the temperature of tower gas still higher, in order to reduce the quantity of cooling water, in this application, make tower gas at first through the air cooler, cool down tower gas, then utilize the water cooler to cool down, under the circumstances of practicing thrift cold volume, can guarantee to liquefy methyl alcohol smoothly.
Furthermore, in the first reactor, the hot point of the catalyst is 250 +/-5 ℃, and in the second reactor, the hot point of the catalyst is 245 +/-5 ℃.
For the second reactor, the first reactor is closer to the circulator and has higher inlet pressure, so the reaction temperature of the first reactor is slightly higher than that of the second reactor, and the catalyst hot spot of the first reactor is slightly higher than that of the second reactor and can be matched with the reaction temperature, so that the reactions in the two reactors can be smoothly carried out.
Further, hot water is used for transferring heat to the first reactor and the second reactor, the hot water enters from the bottoms of the first reactor and the second reactor, and forms a steam-water mixture after absorbing reaction heat and is discharged from the tops of the first reactor and the second reactor; in the first reactor and the second reactor, the temperature of the bed layer is 13-18 ℃ higher than that of the steam-water mixture.
In this application, adopt hot water to move heat, after hot water enters into the reactor, absorb the reaction heat, partial moisture produces the vaporization, form steam-water mixture, because water is in vaporization process, the temperature remains unchanged, for making water keep the heat removal mode under the liquid state, adopt the mode that makes partial moisture vaporization in this application to move heat, can improve and move thermal efficiency, and can make the temperature of reactor be in comparatively even state, avoid the exit temperature difference of reactor too big, and make the partial regional reaction efficiency of reactor lower, can't effectively exert the productivity of reactor.
Specifically, the first reactor and the second reactor have the same structure and are both centrifugal-centripetal radial reactors.
The radial reactor has the advantages of uniform gas distribution and low bed resistance, and can effectively reduce the energy consumption during reaction. The centrifugal-centripetal radial reactor is characterized in that synthesis gas firstly enters an air inlet pipe at the central part of the reactor, then flows outwards in the radial direction and enters an annular space, then flows downwards along the annular space, then flows inwards in the radial direction, enters an exhaust pipe at the central part of the reactor, and finally is discharged out of the reactor through the exhaust pipe, and the centrifugal-centripetal radial reactor is the centrifugal-centripetal radial reactor disclosed by the invention patent of a centrifugal flow beam centripetal water bed reactor with the application number of CN 201911333118.5. After the same reactor is adopted, the same control mode and control point can be adopted, and the production stability is easy to ensure.
The radial reaction gas flow is adopted, and the gas resistance of the reactor is reduced by a large ventilation section; the linear velocity of reaction gas is reduced by a large ventilation section, the residence time of the reaction gas in a catalyst bed layer is delayed to obtain better reaction efficiency, the one-way synthesis rate is high, methanol is produced more, and the reduction of the circulating gas amount is the reduction of the power consumption of a circulator.
The first reactor and the second reactor are both filled with catalyst outside the tubes, so that the filling amount of the catalyst in a high-pressure container is provided, and better space-time yield of the reaction is obtained. Has large specific cold area, and can remove heat in time to realize temperature balance in the reaction area.
Further, a part of the second lean gas is discharged and introduced into the hydrogen recovery apparatus. The discharge point of the second lean gas is set before the second make-up gas is mixed with the second lean gas, namely, after partial second lean gas is emptied, the second make-up gas is sent into the system.
And part of the second lean gas is emptied to reduce the concentration of the non-condensable gas in the system, the emptying of the non-condensable gas is arranged on the second lean gas, and after the second supplementary gas is supplemented, effective components such as hydrogen, carbon monoxide and carbon dioxide are supplemented.
The overall advantages of the present application:
1) the process flow is simple and reasonable in arrangement, the process technology is mature, and the investment of a methanol device is reduced;
2) a two-stage reactor is adopted, the net alcohol value before and after reaction is higher, and the work consumption of circulating power is reduced;
3) because the synthesis reactors are radial reactors, the system resistance is reduced, and the energy consumption is low;
4) the heat in the methanol synthesis process is quickly removed, medium-pressure steam is byproduct, the steam yield is high, the water circulation is solved by adopting a high-position steam drum natural circulation mode, no power consumption is caused, and the high-efficiency energy-saving requirement is met;
5) the fresh gas can be uniformly sent to the first reactor and the second reactor, and the load of the two-stage reactor can be effectively adjusted.
6) The first tower gas outlet and the second tower gas outlet are respectively provided with a separating tank, which is beneficial to the large-scale of the device and reduces the content of methanol in the tower gas as much as possible.
The method is specifically carried out by adopting a two-stage double-separation series-connection synergistic methanol production device, and the methanol production device comprises a first reactor, a second reactor, a first heat exchanger, a second heat exchanger, a first separation tank, a second separation tank and a circulator;
a first discharge hole of the first reactor is communicated with an inlet of a heat medium channel of the first heat exchanger, an outlet of the heat medium channel of the first heat exchanger is communicated with a first material inlet of the first separation tank through a first mixed gas pipe, a first gas outlet of the first separation tank is connected to an inlet of a refrigerant channel of the second heat exchanger through a first lean gas pipe, and an outlet of the refrigerant channel of the second heat exchanger is communicated with a second feed inlet of the second reactor;
a second discharge hole of the second reactor is communicated with an inlet of a heat medium channel for second heat exchange, an outlet of the heat medium channel of the second heat exchanger is communicated with a second material inlet of the second separation tank through a second mixed gas pipe, a second gas outlet of the second separation tank is connected to a gas inlet of the circulator through a second lean gas pipe, and an exhaust port of the circulator is communicated with a first feed inlet of the first reactor after passing through a refrigerant channel of the first heat exchanger;
the raw material pipe is communicated with the first lean gas pipe and the second lean gas pipe; a first liquid discharge port for discharging liquid methanol is arranged at the bottom of the first separation tank, and a second liquid discharge port for discharging liquid methanol is arranged at the bottom of the second separation tank; a first cooler group is connected in series on the first mixed gas pipe, and a second cooler group is connected in series on the second mixed gas pipe;
a first lower water outlet of the first steam drum is communicated with a refrigerant inlet of the first reactor, and a first upper water outlet of the first steam drum is communicated with a refrigerant outlet of the first reactor; and a second descending water port of the second steam pocket is communicated with a refrigerant inlet of the second reactor, and a second ascending water port of the second steam pocket is communicated with a refrigerant outlet of the second reactor. The circulator is a turbine circulator.
The first cooler group comprises a first air cooler and a first water cooler which are connected in series on a first mixed gas pipe, and the second cooler group comprises a second air cooler and a second water cooler which are connected in series on a second mixed gas pipe. The first water cooler is closer to the first separation tank than the first air cooler; the second water cooler is closer to the second separation tank than the second air cooler.
The device is designed aiming at the application, and two reactors are adopted, so that the allocation of a circulator can be reduced, the service efficiency of the circulator is improved, and the work consumption of the circulating power is reduced; the heat in the methanol synthesis process can be quickly removed, medium-pressure steam is byproduct, the steam yield is high, the water circulation is solved by adopting a high-position steam drum natural circulation mode, no power consumption is caused, and the high-efficiency energy-saving requirement is met; fresh synthesis gas as make-up gas can be uniformly fed into the first reactor and the second reactor, and the loads of the two reactors can be effectively adjusted. A separation tank is arranged corresponding to each reactor, so that the device can be enlarged, and the content of methanol entering the tower can be reduced as much as possible. The concentration of the reaction gas is basically the same for each reactor, and the reaction gas can be controlled by approximately the same parameters, so that the stability of process control is effectively improved.
Drawings
FIG. 1 is a schematic flow chart diagram of an embodiment of the present invention.
Detailed Description
The production apparatus used in the present invention will be described below.
Referring to fig. 1, the methanol production apparatus includes a first reactor 11, a second reactor 21, a first heat exchanger 13, a second heat exchanger 23, a first separation tank 16, a second separation tank 26, and a circulator 31.
The first discharge port 112 of the first reactor 11 is communicated with the inlet of the heat medium channel of the first heat exchanger 13, the outlet of the heat medium channel of the first heat exchanger 13 is communicated with the first material inlet 161 of the first separation tank 16 through the first mixed gas pipe 131, the first gas outlet 162 of the first separation tank 16 is connected to the inlet of the refrigerant channel of the second heat exchanger 23 through the first lean gas pipe 17, and the outlet of the refrigerant channel of the second heat exchanger 23 is communicated with the second feed port 211 of the second reactor 21.
The second discharge port 212 of the second reactor 21 is communicated with the inlet of the heat medium channel of the second heat exchanger 23, the outlet of the heat medium channel of the second heat exchanger is communicated with the second material inlet 261 of the second separation tank 26 through a second mixed gas pipe 231, the second gas outlet 262 of the second separation tank 26 is connected to the gas inlet of the circulator 31 through a second lean gas pipe 27, and the gas outlet of the circulator 31 is communicated with the first feed port 111 of the first reactor 11 through the refrigerant channel of the first heat exchanger 13. The circulator in this embodiment employs a turbo compressor.
The raw material pipe 41 is divided into two branch pipes, namely a first raw material branch pipe 42 and a second raw material branch pipe 43, wherein the first raw material branch pipe 42 is communicated with the first lean gas pipe 17, and the second raw material branch pipe 43 is communicated with the second lean gas pipe 27. An outer discharge pipe 271 connected to the second lean gas pipe between the point of connection of the second raw material branch pipe 43 to the first raw material branch pipe 42 and the second separation tank is installed in the second lean gas pipe 27.
The discharge pipe 271 is used to discharge a part of the second lean gas discharged from the second separation tank to reduce the concentration of the non-condensable gas in the system, and the discharged second lean gas is used for hydrogen recovery.
A first drain port 163 for discharging liquid methanol is provided in the bottom of the first separation tank 16, and a second drain port 263 for discharging liquid methanol is provided in the bottom of the second separation tank.
A first cooler group is connected in series to the first mixed gas pipe 131, and in this embodiment, the first cooler group includes a first air cooler 14 and a first water cooler 15 connected in series to the first mixed gas pipe 131, and the first water cooler 15 is located closer to the first separation tank 16 than the first air cooler 14.
A second cooler group is connected in series to the second mixed gas pipe 231; in this embodiment, the second cooler group includes a second air cooler 24 and a second water cooler 25 connected in series to the second mixed gas pipe 231, and the second water cooler 25 is located closer to the second separation tank 26 than the second air cooler 24.
The first steam drum 12 is communicated with a refrigerant inlet 113 at the bottom of the first reactor 11 through a first downcomer 121, and the first steam drum 12 is communicated with a refrigerant outlet 114 at the top of the first reactor through a first upcomer 122. And a first steam discharge port 123 is provided at the top of the first drum 12, and a first water inlet port 124 and a first drain pipe 125 are provided at the bottom of the first drum.
The second steam drum 22 is communicated with a refrigerant inlet 213 at the bottom of the second reactor 21 through a second downcomer 221, and the second steam drum 22 is communicated with a refrigerant outlet 214 at the top of the second reactor through a second upcomer 222. And a second steam discharge port 223 is provided at the top of the second drum 22, and a second water inlet 224 and a second soil discharge pipe 225 are provided at the bottom of the second drum.
In this example, the first reactor and the second reactor are both radial reactors of the centrifugal-centripetal type.
A double-stage double-separation methanol production method adopts the methanol production device and comprises the following steps:
(1) the raw material gas 810 travels along the raw material pipe and is divided into two streams, which are a first supplementary gas and a second supplementary gas, wherein the second supplementary gas is mixed with a second lean gas discharged from the second separation tank 26 along the second raw material branch pipe 43 to form a second mixed gas, the second mixed gas is compressed by the circulator 31, flows through the refrigerant channel of the first heat exchanger 13, and then enters the first reactor 11 for reaction, and the reacted gas is discharged from the first reactor to become a first tower gas.
(2) The first tower gas firstly exchanges heat with the second mixed gas through the heat medium channel of the first heat exchanger 13 to heat the second mixed gas and reduce the temperature of the first tower gas. Namely, the first tower outlet gas heats the second mixed gas through the first heat exchanger.
The first tower gas passes through the first heat exchanger 13, then sequentially passes through the first air cooler 14 and the first water cooler 15 for condensation, and then enters the first separation tank 16 for gas-liquid separation, the liquid in the first separation tank is discharged through the first liquid discharge port 163 at the bottom of the first separation tank to form first crude methanol 830, and the first crude methanol 830 enters the next process for methanol refining.
The gas in the first separation tank is discharged from the first gas outlet 162 at the top to form a first lean gas.
(3) The first lean gas and the second make-up gas from the first raw material branch pipe 42 are formed into a first mixed gas, the first mixed gas passes through the refrigerant passage of the second heat exchanger 23 and enters the second reactor 21 to react, and the reacted gas is discharged from the second reactor to become a second tower gas.
(4) The second tower gas firstly exchanges heat with the first mixed gas through the heat medium channel of the second heat exchanger 23 to heat the first mixed gas and reduce the temperature of the second tower gas. Namely, the second tower outlet gas heats the first mixed gas through the second heat exchanger.
The second tower gas passes through the second heat exchanger 23, then sequentially passes through the second air cooler 24 and the second water cooler 25 for condensation, and then enters the second separation tank 26 for gas-liquid separation, the liquid in the second separation tank is discharged through the second liquid outlet 263 at the bottom of the second separation tank to form second crude methanol 840, and the second crude methanol 840 enters the next process for methanol refining.
The gas in the second separation tank is discharged from the second gas outlet 262 at the top to form a second lean gas. And the second lean gas and the second make-up gas form a second mixed gas, and the second mixed gas is compressed by the circulator and then circulated.
A portion of the second lean gas is vented to form a purge gas 820, and the purge gas 820 is passed to a hydrogen recovery device.
In this example, the standard volume ratio of the first lean gas to the first make-up gas is 2.49: 1; the standard volume ratio of the second lean gas to the second make-up gas is 2.53: 1. in the present embodiment, the standard volume ratio of the first lean gas to the second lean gas is 1: 1.
In this example, the molar ratio of hydrogen gas was 67.2%, the molar ratio of carbon monoxide was 30%, the molar ratio of carbon dioxide was 2.38, and the molar ratio of other gases was 0.42% in the feed gas.
The inlet temperature of the second mixed gas in the first reactor is 220 ℃, the outlet temperature of the first tower gas is 250 ℃, and the reaction pressure of the first reactor is 8.1 MPaG;
the inlet temperature of the first mixed gas in the second reactor is 211 ℃, the outlet temperature of the second tower outlet gas is 240 ℃, and the reaction pressure of the second reactor is 7.8 MPaG.
The temperature of the first tower outlet gas is reduced to 120 ℃ after passing through a first heat exchanger, then the temperature of the first tower outlet gas is reduced to 60 ℃ through a first air cooler, and finally the temperature of the first tower outlet gas is reduced to 40 ℃ through a first water cooler;
and the temperature of the second tower outlet gas is reduced to 108 ℃ after passing through a second heat exchanger, then is reduced to 60 ℃ by a second air cooler, and finally is reduced to 40 ℃ by a second water cooler.
In the present application, the catalyst hot spot is 250 + -5 ℃ in the first reactor, and 245 + -5 ℃ in the second reactor.
And hot water is used for transferring heat to the first reactor and the second reactor, enters from the bottoms of the first reactor and the second reactor, absorbs the reaction heat to form a steam-water mixture, and is discharged from the tops of the first reactor and the second reactor.
Specifically, in this embodiment, the hot water in the first steam drum 12 enters the heat exchange tube of the first reactor from the bottom through the first descending tube 121, absorbs the reaction heat, part of the hot water is vaporized to form a steam-water mixture, flows upward along the heat exchange tube and is discharged from the top of the first reactor, and then returns to the first steam drum 12 along the first ascending tube 122, and part of the hot water in the first steam drum is flashed to form steam, in this embodiment, the steam flashed from the first steam drum is medium-pressure steam of 2.5 MPaG. The medium pressure steam generated by the first steam drum is discharged into the steam pipe network through the first steam discharge port 123. Make-up soft water enters the first drum through a first water inlet 124 at the bottom of the first drum. During parking maintenance, the waste water is discharged from the first drain pipe 125 at the bottom of the first drum.
Hot water in the second steam drum 22 enters the heat exchange tube of the second reactor from the bottom through the second downcomer 221, reaction heat is absorbed, part of the hot water is vaporized to form a steam-water mixture, the steam-water mixture flows upwards along the heat exchange tube and is discharged from the top of the second reactor, then the steam-water mixture returns to the second steam drum 22 along the second riser 222, part of the hot water in the second steam drum is flashed to form steam, and in the embodiment, the steam flashed in the second steam drum is medium-pressure steam of 2.5 MPaG. The intermediate pressure steam generated by the second steam drum is discharged into the steam pipe network through the second steam discharge port 223. Make-up soft water enters the second drum through a second water inlet 224 in the bottom of the second drum. During parking for maintenance, the waste water is discharged from the second sewage draining pipe 225 at the bottom of the second steam drum.
In this example, the bed temperatures in the first reactor and the second reactor were both 15-17 ℃ higher than the temperature of the steam-water mixture.
In the application, the first reactor and the second reactor are both centrifugal-centripetal radial reactors, and particularly, the invention patent of a centrifugal-centripetal flow tubular water bed reactor with the application number of CN201911333118.5 is adopted.
The composition, temperature and pressure of the streams in this example are shown in Table 1.
TABLE 1
Figure BDA0002657306490000071
Figure BDA0002657306490000081
Some of the process parameters in this example are listed in Table 2
TABLE 2
Index (I) Numerical value and Unit
Fresh gas amount 551000Nm3/h
Amount of circulating gas 971848Nm3/h
Catalyst loading 162m3
First reactor inlet pressure 7.92MPa
First reactor inlet pressure 7.55MPa
First reactor pressure drop ≤0.1MPa
Pressure drop in the second reactor ≤0.1MPa
Total pressure drop in the circuit ≤0.8MPa
Power consumption of circulator 2792kW
Total heat of reaction with steam removal 197.9MW
It can be seen through table 1 and table 2 that, after adopting this application, whole reaction system is comparatively steady, and the pressure drop of system is lower, can reduce the running cost to can furthest turn into steam with the reaction heat, reduce the waste of reaction heat.

Claims (10)

1. A double-stage double-separation methanol production method is characterized by comprising the following steps:
(1) compressing a second mixed gas containing a second make-up gas and a second lean gas by a circulator, then feeding the second mixed gas into a first reactor for reaction, and discharging a first tower outlet gas from the first reactor;
(2) after methanol is recovered from the first tower gas, a first lean gas is formed;
(3) mixing the first lean gas and the first make-up gas to form a first mixed gas, allowing the first mixed gas to enter a second reactor for reaction, and discharging a second tower gas from the second reactor;
(4) after methanol is recovered from the second tower gas, a second lean gas is formed;
the first tower outlet gas heats the second mixed gas through a first heat exchanger;
the second tower outlet gas heats the first mixed gas through a second heat exchanger.
2. The dual stage dual separation methanol production process of claim 1,
the standard volume ratio of the first lean gas to the first make-up gas is (2-3): 1;
the standard volume ratio of the second lean gas to the second make-up gas is (2-3): 1.
3. the dual stage dual separation methanol production process of claim 1,
in the first make-up gas and the second make-up gas, (H)2-CO2) With (CO + CO)2) The mole ratio of (A) is 2.2-2.3, and the mole percentage of carbon dioxide is 2-3%.
4. The dual stage dual separation methanol production process of claim 3,
in the first make-up gas and the second make-up gas, H2The total molar ratio of S to COS is less than or equal to 0.1 ppm.
5. The dual stage dual separation methanol production process of claim 1,
the inlet temperature of the second mixed gas in the first reactor is 210-240 ℃, the outlet temperature of the first tower outlet gas is 245-250 ℃, and the reaction pressure of the first reactor is 7.5-8.5 MPaG;
the inlet temperature of the first mixed gas in the second reactor is 210-240 ℃, the outlet temperature of the second tower outlet gas is 230-240 ℃, and the reaction pressure of the second reactor is 7.5-8.5 MPaG.
6. The dual stage dual separation methanol production process of claim 5,
the temperature of the first tower outlet gas is reduced to 120-130 ℃ after passing through a first heat exchanger, then the temperature of the first tower outlet gas is reduced to 60 ℃ through a first air cooler, and finally the temperature of the first tower outlet gas is reduced to 40 ℃ through a first water cooler;
the temperature of the second tower outlet gas is reduced to 90-110 ℃ after passing through a second heat exchanger, then the temperature is reduced to 60 ℃ by a second air cooler, and finally the temperature is reduced to 40 ℃ by a second water cooler.
7. The dual stage dual separation methanol production process of claim 1,
in the first reactor, the catalyst hot spot is 250 + -5 deg.C, and in the second reactor, the catalyst hot spot is 245 + -5 deg.C.
8. The two-stage double-separation methanol production method of claim 7, wherein the first reactor and the second reactor are subjected to heat transfer by hot water, the hot water enters from the bottom of the first reactor and the second reactor, and after absorbing reaction heat, a steam-water mixture is formed and is discharged from the top of the first reactor and the second reactor;
in the first reactor and the second reactor, the temperature of the bed layer is 13-18 ℃ higher than that of the steam-water mixture.
9. The dual stage dual separation methanol production process of claim 1,
part of the second lean gas is vented and passed to a hydrogen recovery unit.
10. The dual stage dual separation methanol production process of claim 1,
the first reactor and the second reactor have the same structure and are both centrifugal-centripetal radial reactors.
CN202010892255.9A 2020-08-31 2020-08-31 Two-stage double-separation methanol production method Pending CN112125779A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114632477A (en) * 2022-03-23 2022-06-17 中国神华煤制油化工有限公司 Methanol synthesis method and methanol synthesis system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105753646A (en) * 2016-02-16 2016-07-13 南京国昌化工科技有限公司 Energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation method and energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation device
CN206767964U (en) * 2017-04-28 2017-12-19 中石化宁波工程有限公司 Low pressure methanol synthesis system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105753646A (en) * 2016-02-16 2016-07-13 南京国昌化工科技有限公司 Energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation method and energy-saving inter-section high low temperature gradient alcohol-division two-stage alcohol generation device
CN206767964U (en) * 2017-04-28 2017-12-19 中石化宁波工程有限公司 Low pressure methanol synthesis system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114632477A (en) * 2022-03-23 2022-06-17 中国神华煤制油化工有限公司 Methanol synthesis method and methanol synthesis system

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