CN114261964A - Method and device for treating carbon dioxide feed gas - Google Patents
Method and device for treating carbon dioxide feed gas Download PDFInfo
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- CN114261964A CN114261964A CN202210009349.6A CN202210009349A CN114261964A CN 114261964 A CN114261964 A CN 114261964A CN 202210009349 A CN202210009349 A CN 202210009349A CN 114261964 A CN114261964 A CN 114261964A
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Abstract
The invention relates to the technical field of preparation of food-grade and high-purity carbon dioxide, in particular to a method and a device for treating carbon dioxide feed gas. The invention utilizes the reaction heat of hydrogen to improve the temperature rise of a bed layer, thereby reducing the load of an electric heater in front of a dealkylation reactor, reducing the concentration of total sulfur in the front of the dealkylation reactor by using a high-efficiency desulfurization method, prolonging the service life of a dealkylation catalyst, and simultaneously reducing the risk of sulfide stress corrosion of a dealkylation preheater. Part of the raw material gas after the raw material gas is desulfurized is not sent to a hydrocarbon removing process but is directly liquefied after being sent to a drying process for water removal and then sent to an intermediate storage tank, and the boiling point of hydrogen is far lower than that of CO2The hydrogen is subjected to flash evaporation concentration in an intermediate storage tank, and the flash evaporation gas contains about 7 percent of hydrogen. The flash evaporation gas is mixed into the raw material gas according to the proportion, the proportion of the hydrogen in the raw material gas is improved by about 1.5 percent, the temperature of an outlet of an electric heater in front of the dealkylation tower is reduced from about 320 ℃ to about 260 ℃, and the energy consumption is reduced.
Description
Technical Field
The invention relates to the technical field of preparation of food-grade and high-purity carbon dioxide, in particular to a method and a device for treating carbon dioxide feed gas.
Background
The feed gas from upstream contains a high concentration of CO2Small amount of sulfur and H2Impurities such as alkane, benzene, alkene, alcohol hydrocarbon and the like, and aims to ensure that sulfur and hydrocarbon impurities in the raw material gas are removed to be below the indexes (sulfur) specified by the national standard of food-grade carbon dioxide<0.1ppm, less than or equal to 50ppm of total hydrocarbon and less than or equal to 20ppm of non-methane hydrocarbon), adding a small excess of oxygen into the raw material gas, performing a compression process, then performing a desulfurization process to reduce the sulfur in the raw material gas to below 0.1ppm, and then performing a dealkylation process to perform an oxidation reaction on hydrocarbons such as alkane, benzene and alcohol and oxygen in a dealkylation reactor filled with a catalyst to convert the hydrocarbons into CO2. Namely, the raw material gas is subjected to a compression process, is desulfurized and then enters a dealkylation preheater and high-temperature CO at the outlet of a dealkylation reactor2And (3) heat exchange and temperature rise are carried out, and the heated feed gas reaches the reaction temperature of the hydrocarbon removal bed layer after passing through the electric heater, so that the hydrocarbon substances can be removed efficiently. Under normal working conditions, in order to ensure the hydrocarbon removing effect, the temperature of the electric heater in front of the hydrocarbon removing reactor is increased to about 320 ℃ under the load of about 60%, and under the condition that the hydrocarbon concentration in the raw material gas is low due to fluctuation of the upstream working conditions, the load of the electric heater is increased from 60% to 80% or even 100%, so that the energy consumption of the hydrocarbon removing process is high, and the hydrocarbon removing preheater has the risk of stress corrosion cracking under the environment that condensed water exists after the reaction of sulfide and hydrocarbon removing. Fig. 1 is a diagram of a treatment device adopted in the existing treatment process of raw material gas, and specifically comprises the following steps:
(1) compression procedure
The sulfur and H contained in small amount from upstream2Carbon dioxide content of impurities such as alkane, benzene, alkene, alcohol hydrocarbon, etc>Mixing 90% of raw gas with slightly excessive oxygen in chemical reaction regulated by regulating valve D-1 controlled by flowmeter, compressing by primary compressor D-2 to 0.3MPa, secondary compressor D-3 to 0.9MPa, tertiary compressor D-4 to 2.3MPa, and discharging from tertiary compressor D-4 containing sulfur and H2Carbon dioxide gas and oxygen gas containing impurities such as alkane, benzene, alkene, alcohol hydrocarbon, etcAt 40 c and then sent to the desulfurization process.
(2) Desulfurization step
From the compression step, containing small amounts of sulfur and H2Carbon dioxide content of impurities such as alkane, benzene, alkene, alcohol hydrocarbon, etc>After 90% of the raw material gas passes through the desulfurizing tower D-5, the total sulfur concentration is reduced to be less than 0.1ppm, and under the condition of fluctuation of upstream working conditions, the total sulfur concentration after desulfurization cannot be reduced to be less than 0.1 ppm.
(3) Hydrocarbon removal process
From desulfurization trains containing trace amounts of sulfur, small amounts of H2The carbon dioxide raw material gas of impurities such as alkane, benzene, olefin, alcohol hydrocarbon and the like is preheated to about 260 ℃, then is heated to about 320 ℃ by a dealkylation heater D-7, and finally enters a dealkylation reactor D-8. In the de-passing reactor D-8, H2Impurities such as alkane, benzene, alkene, alcohol hydrocarbon and the like and oxygen are subjected to chemical reaction under the action of a catalyst to generate carbon dioxide and water. After the hydrocarbon is removed, the high-temperature raw gas is subjected to heat exchange with the raw gas before the hydrocarbon is removed through the hydrocarbon removal preheater D-6, the high-temperature raw gas still contains trace sulfide, the hydrocarbon removal preheater has the risk of sulfide stress corrosion in the environment with condensed water after the heat exchange, under the condition of sulfide poisoning, the sulfur poisoning is determined according to the severity of the poisoning, and in the severe case, the service life of the hydrocarbon removal catalyst is generally not more than 1 year. The purity of the raw material gas after the hydrocarbon removal is higher than 99.9 percent, the total hydrocarbon in the carbon dioxide raw material gas after the hydrocarbon removal is reduced to below 50ppm, and the carbon dioxide raw material gas enters a subsequent treatment system.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a method and an apparatus for processing a carbon dioxide feed gas, the processing method provided by the present invention has low energy consumption, the service life of the dealkylation catalyst is long, and the dealkylation preheater is not prone to stress corrosion cracking of the oversulfide.
The invention provides a method for treating carbon dioxide feed gas, which comprises the following steps:
A) mixing raw material gas, oxygen and carbon dioxide gas with high hydrogen content, wherein the volume content of hydrogen in the obtained mixed gas is increased by 1.3-1.7% compared with the volume content of hydrogen in the raw material gas;
B) compressing the mixed gas to obtain compressed gas with the pressure of 2.1-2.5 MPa;
C) removing H from the compressed gas under the action of a first desulfurizing agent2S；
Converting organic sulfur into inorganic sulfur under the action of a second desulfurizer;
finally, removing inorganic sulfur under the action of a third desulfurizer to obtain desulfurized gas;
D) preheating part of the desulfurized gas to 255-265 ℃, reacting with oxygen under the action of a catalyst to generate mixed gas containing high-temperature carbon dioxide and water vapor, and performing heat exchange with part of the gas in the desulfurized gas;
and (4) drying, liquefying and evaporating and concentrating residual gas in the desulfurized gas to obtain carbon dioxide gas with high hydrogen content, and reusing the carbon dioxide gas in the step A).
Preferably, in step a), the volume concentration of carbon dioxide in the feed gas is > 90%;
impurities in the feed gas include sulfur, hydrogen, alkanes, benzene, alkenes, and alcohol hydrocarbons;
the volume content of hydrogen in the feed gas is 0.3-0.7%;
the water content in the feed gas is 2800-3200 ppm;
in the carbon dioxide gas with high hydrogen content, the volume content of hydrogen is 6-8%.
Preferably, in the step B), the compression comprises first-stage compression, second-stage compression and third-stage compression;
the gas pressure after the first-stage compression is 0.1-0.3 MPa;
and the gas pressure after the secondary compression is 0.3-1.1 MPa.
Preferably, in the step C), the first desulfurizing agent includes compound iron oxide; the volume space velocity of the first desulfurizing agent is 1000/h-1500/h;
the second desulfurizing agent comprises ferric oxide and water vapor; the volume space velocity of the second desulfurizing agent is 1000/h-1500/h;
the third desulfurizing agent comprises activated carbon; the volume space velocity of the third desulfurizing agent is 1000/h-1500/h.
Preferably, in step C), the compressed gas is subjected to H removal under the action of a first desulfurizing agent2The temperature of S is 25-70 ℃;
conversion of organic sulfur to H2The temperature of S is 75-85 ℃;
removing H under the action of a third desulfurizing agent2The temperature of S is 30-80 ℃;
the sulfide concentration of the desulfurization gas is not higher than 0.01 ppm.
Preferably, in the step D), the load of an electric heater required for preheating part of the gas in the desulfurization gas to 255-265 ℃ is 0% -30%;
the catalyst comprises RE-Pd-Pt/Al doped with rare earth elements2O3A catalyst;
the reaction temperature is 255-265 ℃.
Preferably, in the step D), part of the gas in the desulfurized gas accounts for 70-90% by volume of the desulfurized gas;
the total hydrocarbon content in the mixed gas of the high-temperature carbon dioxide and the water vapor is not higher than 10 ppm.
Preferably, in the step D), the residual gas in the desulfurized gas accounts for 10-30% by volume of the desulfurized gas;
the water content of the dried gas is below 5 ppm;
in the carbon dioxide gas with high hydrogen content, the volume content of hydrogen is 6-8%.
The invention also provides a device for treating the carbon dioxide feed gas, which comprises:
a gas mixing device;
the gas compression device is connected with the gas outlet of the gas mixing device;
the first-stage desulfurizing tower is connected with a gas outlet of the gas compression device;
the second-stage desulfurizing tower is connected with the gas outlet of the first-stage desulfurizing tower;
the third-stage desulfurizing tower is connected with the gas outlet of the second-stage desulfurizing tower;
part of gas discharged by the three-stage desulfurization tower enters the preheater from a cold gas inlet of the preheater;
a hydrocarbon-removing electric heater connected with the hot gas outlet of the preheater;
the de-hydrocarbon reactor is connected with the gas outlet of the de-hydrocarbon electric heater; the gas outlet of the dealkylation reactor is connected with the hot gas inlet of the preheater;
the residual gas discharged by the third-stage desulfurizing tower enters a drying tower;
a liquefier connected to the gas outlet of the drying tower;
an intermediate storage tank connected to the outlet of the liquefier; the outlet of the intermediate storage tank is connected with the recycled carbon dioxide gas inlet with high hydrogen content of the gas mixing device.
Preferably, the gas compressing apparatus includes:
the primary compressor is connected with a gas outlet of the gas mixing device;
a secondary compressor connected to the gas outlet of the primary compressor;
the three-stage compressor is connected with a gas outlet of the two-stage compressor;
and a gas outlet of the third-stage compressor is connected with a gas inlet of the first-stage desulfurizing tower.
The invention utilizes the reaction heat of hydrogen to improve the temperature rise of the bed layer, thereby reducing the load of an electric heater in front of the dealkylation reactor; the method for efficiently desulfurizing reduces the concentration of total sulfur (the total sulfur concentration is reduced to be less than 0.01ppm) before the hydrocarbon is removed, prolongs the service life of the hydrocarbon removal catalyst, and simultaneously reduces the risk of sulfide stress corrosion of a pre-heater of the hydrocarbon removal. Under normal airspeed, every time 1% (volume percentage) of hydrogen is added, the bed temperature of the dealkylation reactor is raised to about 40 deg.C, and in the method, part of raw material gas after the raw material gas is desulfurized is directly liquefied after it is passed through drying procedure instead of dealkylation procedureEnters an intermediate storage tank because the boiling point of hydrogen is far lower than that of CO2The hydrogen is subjected to flash evaporation concentration in an intermediate storage tank, and the flash evaporation gas contains about 7 percent of hydrogen. The method is characterized in that the flash evaporation gas is mixed into the raw material gas according to a proportion, the proportion of hydrogen in the raw material gas is improved by about 1.5%, the temperature of an outlet of an electric heater in front of a dealkylation tower is reduced from about 320 ℃ to about 260 ℃ so as to meet the requirement of temperature rise energy consumption of a dealkylation bed layer, and the load of the electric heater is reduced from 60-100% to 30-0% so that the energy consumption is reduced. The high-efficiency desulfurization technology adopts a three-stage fine desulfurization process, and the sulfur and H from the compression process contain a small amount of sulfur2Removing H from carbon dioxide raw material gas containing impurities such as alkane, benzene, olefin, alcohol hydrocarbon and the like through a primary desulfurizing tower2S, then the sulfur is fed into a secondary desulfurization tower to convert organic sulfur into inorganic sulfur H which is easy to remove2S, then entering a three-stage desulfurizing tower to remove H2S。
In the application of the technical scheme, the load of the electric heater in front of the dealkylation tower is reduced by 150kW per hour, and 120 ten thousand kW.h can be saved all the year round; after the total sulfur of the feed gas is reduced to be less than 0.01ppm after three-stage high-efficiency desulfurization, the service life of the dealkylation catalyst reaches 6 years, and the condition that the sulfide stress corrosion cracking does not occur in the dealkylation preheater.
The concentration of carbon dioxide in the treated gas obtained by the treatment method provided by the invention is higher, and the concentration of impurities is lower.
Drawings
FIG. 1 is a diagram of a treatment device adopted in a prior treatment process of raw material gas;
fig. 2 is a diagram of a carbon dioxide raw gas treatment device according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.
The invention provides a method for treating carbon dioxide feed gas, which comprises the following steps:
A) mixing raw material gas, oxygen and carbon dioxide gas with high hydrogen content, wherein the volume content of hydrogen in the obtained mixed gas is increased by 1.3-1.7% compared with the volume content of hydrogen in the raw material gas;
B) compressing the mixed gas to obtain compressed gas with the pressure of 2.1-2.5 MPa;
C) removing H from the compressed gas under the action of a first desulfurizing agent2S；
Converting organic sulfur into inorganic sulfur under the action of a second desulfurizer;
finally, removing inorganic sulfur under the action of a third desulfurizer to obtain desulfurized gas;
D) preheating part of the desulfurized gas to 255-265 ℃, reacting with oxygen under the action of a catalyst to generate mixed gas containing high-temperature carbon dioxide and water vapor, and performing heat exchange with part of the gas in the desulfurized gas;
and (4) drying, liquefying and evaporating and concentrating residual gas in the desulfurized gas to obtain carbon dioxide gas with high hydrogen content, and reusing the carbon dioxide gas in the step A).
In certain embodiments of the invention, the volume concentration of carbon dioxide in the feed gas is > 90%. In certain embodiments, the volume concentration of carbon dioxide in the feed gas is 98%. In certain embodiments of the invention, the impurities in the feed gas include sulfur, hydrogen, alkanes, benzene, alkenes, and alcohol hydrocarbons. In certain embodiments of the present invention, the volume content of hydrogen in the feed gas is between 0.3% and 0.7%. In certain embodiments, the volume content of hydrogen in the feed gas is 0.7%.
In certain embodiments of the present invention, the feed gas has a water content of 2800 to 3200 ppm.
In certain embodiments of the present invention, the high hydrogen content carbon dioxide gas has a hydrogen content of 6% to 8% by volume. In certain embodiments, the high hydrogen content carbon dioxide gas has a hydrogen content of 7% by volume.
In certain embodiments of the invention, the hydrogen content of the mixed gas is increased by 1.5% by volume compared to the hydrogen content of the feed gas.
And after the mixed gas is obtained, compressing the mixed gas to obtain compressed gas with the pressure of 2.1-2.5 MPa. In certain embodiments, the resulting compressed gas has a pressure of 2.3 MPa.
In some embodiments of the invention, the compression comprises one stage of compression, two stages of compression, and three stages of compression.
In some embodiments of the invention, the gas pressure after the first stage of compression is 0.1-0.3 MPa. In certain embodiments, the gas pressure after the one-stage compression is 0.3 MPa.
In some embodiments of the invention, the gas pressure after the two-stage compression is 0.3-1.1 MPa. In certain embodiments, the gas pressure after the secondary compression is 0.9 MPa.
After obtaining the compressed gas, removing H from the compressed gas under the action of a first desulfurizer2S。
In certain embodiments of the invention, the first desulfurizing agent comprises a complex iron oxide, the main component being Fe2O3The source of the composite iron oxide may be generally commercially available, such as composite iron oxide manufactured by zhengzhou encyclopedia materials ltd. The first desulfurizing agent can remove H2S, make H2S is converted into elemental sulfur and solid sulfide, and the first desulfurizing agent can be replaced after losing the removing effect.
In certain embodiments of the invention, the first desulfurizing agent has a volumetric space velocity of 1000/h to 1500/h. In certain embodiments, the first desulfurizing agent has a volumetric space velocity of 1000/h.
In certain embodiments of the invention, the compressed gas is subjected to H removal by the action of a first desulfurizing agent2The temperature of S is 25-70 ℃. In certain embodiments, the compressed gas is subjected to H removal by the action of a first desulfurizing agent2The temperature of S was 40 ℃.
Then under the action of a second desulfurizing agent, organic sulfur is converted into H2S。
In some embodiments of the present invention, the second desulfurizing agent comprises iron oxide, and during the desulfurization process under the action of the second desulfurizing agent, water in the feed gas is converted into water vapor, and the iron oxide cooperates with the water vapor to convert organic sulfur into inorganic sulfur H which is easier to remove2And S. The amount of the water vapor is controlled by controlling the water content in the raw material gas, and in certain embodiments of the invention, the water content in the raw material gas is 2800-3200 ppm.
In certain embodiments of the present invention, the second desulfurizing agent has a volumetric space velocity of 1000/h to 1500/h. In certain embodiments, the second desulfurizing agent has a volumetric space velocity of 1000/h.
In certain embodiments of the present invention, organic sulfur is converted to H2The temperature of S is 75-85 ℃. In certain embodiments, the organic sulfur is converted to H2The temperature of S was 80 ℃.
And finally, removing inorganic sulfur under the action of a third desulfurizing agent to obtain the desulfurization gas.
In certain embodiments of the present invention, the third desulfurization agent comprises activated carbon. Used for removing inorganic sulfur.
In certain embodiments of the present invention, the volume space velocity of the third desulfurizing agent is from 1000/h to 1500/h. In certain embodiments, the third desulfurizing agent has a volumetric space velocity of 1000/h.
In certain embodiments of the invention, H is removed by the action of a third desulfurizing agent2The temperature of S is 30-80 ℃. In certain embodiments, the removal of H is effected by a third desulfurizing agent2The temperature of S was 50 ℃.
In certain embodiments of the present invention, the desulfurized gas has a sulfide concentration of no greater than 0.01 ppm. In certain embodiments, the desulfurized gas has a sulfide concentration of 0.01 ppm.
After the desulfurized gas is obtained, preheating part of the desulfurized gas to 255-265 ℃, reacting with oxygen under the action of a catalyst to generate mixed gas containing high-temperature carbon dioxide and water vapor, and performing heat exchange with part of the desulfurized gas.
In certain embodiments of the present invention, a portion of the gas in the sweetened gas is between 70% and 90% by volume of the sweetened gas. In certain embodiments, a portion of the desulfurized gas comprises 70% by volume of the desulfurized gas.
In some embodiments of the invention, the load of the electric heater required for preheating part of the gas in the desulfurization gas to 255-265 ℃ is 0% -30% or 1% -30%. In some embodiments, preheating a portion of the desulfurized gas to 255-265 ℃ requires a 30% duty on electric heater.
In certain embodiments of the invention, the catalyst comprises RE-Pd-Pt/Al doped with a rare earth element2O3The catalyst, namely palladium and platinum catalyst, is doped with a small amount of rare earth, and alumina is used as a carrier. In certain embodiments of the invention, the RE-Pd-Pt/Al2O3In the catalyst, the mass content of palladium is 0.08-0.12%, the mass content of platinum is 0.03-0.07%, and the mass content of rare earth elements is 0.001-0.002%. In certain embodiments, the RE-Pd-Pt/Al2O3In the catalyst, the mass content of palladium is 0.1%, the mass content of platinum is 0.05%, and the mass content of rare earth elements is 0.001%.
The invention is suitable for the RE-Pd-Pt/Al2O3The source of the catalyst is not particularly limited, and may be generally commercially available.
In certain embodiments of the present invention, the temperature of the reaction is 255 to 265 ℃. In some embodiments of the present invention, the reaction time is 2.25 to 3 seconds. In certain embodiments, the reaction time is 2.5 s.
In certain embodiments of the present invention, the mixed gas of high-temperature carbon dioxide and steam has a total hydrocarbon content of not higher than 10 ppm. In certain embodiments, the mixed gas of high-temperature carbon dioxide and steam has a total hydrocarbon content of 10 ppm. In the present invention, the flow rate of oxygen in step A) is controlled by controlling the total hydrocarbon content of not more than 10ppm after the reaction of oxygen and the hydrocarbon in the desulfurization gas in the dealkylation reactor.
In the present invention, the mixed gas of the high-temperature carbon dioxide and the steam exchanges heat with a part of the gas in the desulfurized gas, and specifically, the mixed gas of the high-temperature carbon dioxide and the steam provides preheating energy for the part of the gas in the desulfurized gas, and the temperature of the mixed gas of the high-temperature carbon dioxide and the steam is reduced.
In some embodiments of the present invention, the mixed gas after heat exchange enters a water cooler to be cooled and dehydrated, so as to obtain carbon dioxide gas with higher purity.
And (4) drying, liquefying and evaporating and concentrating residual gas in the desulfurized gas to obtain carbon dioxide gas with high hydrogen content, and reusing the carbon dioxide gas in the step A).
In certain embodiments of the present invention, the residual gas in the desulfurized gas comprises from 10% to 30% by volume of the desulfurized gas. In certain embodiments, the remaining gas in the sweetened gas comprises 30% by volume of the sweetened gas.
In certain embodiments of the invention, the water content of the dried gas is below 5 ppm. In certain embodiments, the water content of the dried gas is 3 ppm.
The method and parameters for liquefaction are not particularly limited in the present invention, and methods and parameters for liquefaction known to those skilled in the art may be used.
In the present invention, the concentration by evaporation is carried out in the intermediate storage tank because of H2Is low and is easily flashed out.
In certain embodiments of the present invention, the high hydrogen content carbon dioxide gas has a hydrogen content of 6% to 8% by volume. In certain embodiments, the high hydrogen content carbon dioxide gas has a hydrogen content of 7% by volume.
The source of the above-mentioned raw materials is not particularly limited, and the raw materials may be generally commercially available.
The invention also provides a device for treating the carbon dioxide feed gas, which comprises:
a gas mixing device; the gas mixing device is provided with a raw material gas inlet, an oxygen inlet, a carbon dioxide gas inlet with high hydrogen content and a carbon dioxide gas inlet for recycling high hydrogen content;
the gas compression device is connected with the gas outlet of the gas mixing device;
the first-stage desulfurizing tower is connected with a gas outlet of the gas compression device;
the second-stage desulfurizing tower is connected with the gas outlet of the first-stage desulfurizing tower;
the third-stage desulfurizing tower is connected with the gas outlet of the second-stage desulfurizing tower;
part of gas discharged by the three-stage desulfurization tower enters the preheater from a cold gas inlet of the preheater;
a hydrocarbon-removing electric heater connected with the hot gas outlet of the preheater;
the de-hydrocarbon reactor is connected with the gas outlet of the de-hydrocarbon electric heater; the gas outlet of the dealkylation reactor is connected with the hot gas inlet of the preheater;
the residual gas discharged by the third-stage desulfurizing tower enters a drying tower;
a liquefier connected to the gas outlet of the drying tower;
an intermediate storage tank connected to the outlet of the liquefier; the outlet of the intermediate storage tank is connected with the recycled carbon dioxide gas inlet with high hydrogen content of the gas mixing device.
Fig. 2 is a diagram of a carbon dioxide raw gas treatment device according to an embodiment of the present invention. Wherein, 1 is a gas mixing device; 2 is a first-stage compressor; 3 is a two-stage compressor; 4 is a three-stage compressor; 2.3, 4 constitute a gas compression device; 5 is a first-stage desulfurizing tower; 6 is a secondary desulfurizing tower; 7 is a three-stage desulfurizing tower; 8 is a preheater; 9 is an electric heater for removing hydrocarbon; 10 is a dealkylation reactor; 11 is a drying tower; 12 is a liquefier; and 13 is an intermediate storage tank.
The apparatus for treating a carbon dioxide raw gas comprises a gas mixing device 1. The gas mixing device is used for mixing raw material gas, oxygen and carbon dioxide gas with high hydrogen content. The gas mixing device is provided with a raw material gas inlet, an oxygen inlet, a carbon dioxide gas inlet with high hydrogen content and a carbon dioxide gas inlet for recycling the high hydrogen content.
In certain embodiments of the invention, the gas mixing device is a gas mixer. The source of the gas mixer is not particularly limited in the present invention, and may be generally commercially available.
The device for treating the carbon dioxide raw material gas further comprises a gas compression device. The gas compression device is used for compressing the mixed gas.
In certain embodiments of the present invention, the gas compression device comprises:
the primary compressor 2 is connected with a gas outlet of the gas mixing device;
a secondary compressor 3 connected to the gas outlet of the primary compressor;
and a tertiary compressor 4 connected to the gas outlet of the secondary compressor.
The present invention is not particularly limited to the kind and source of the first-stage compressor, the second-stage compressor and the third-stage compressor, and may be a general commercially available compressor.
The device for treating the carbon dioxide feed gas further comprises a primary desulfurizing tower 5. The primary desulfurization tower is used for first desulfurization of the compressed gas. And the gas inlet of the primary desulfurization tower is connected with the gas outlet of the gas compression device. In certain embodiments of the present invention, the gas inlet of the primary desulfurization tower is connected to the gas outlet of the tertiary compressor.
In some embodiments of the present invention, the first-stage desulfurization tower is a pressure vessel containing a first desulfurizing agent, and the first desulfurizing agent is fixed by a filter screen plate and ceramic balls. In certain embodiments of the present invention, the primary desulfurization tower is a generally commercially available stainless steel pressure vessel, which is filled with a first desulfurizing agent as needed. The filter screen plate and the porcelain ball are all generally sold in the market.
The device for treating the carbon dioxide feed gas further comprises a secondary desulfurizing tower 6. The secondary desulfurization tower is used for secondary desulfurization of the compressed gas. And the gas inlet of the secondary desulfurization tower is connected with the gas outlet of the primary desulfurization tower.
In some embodiments of the present invention, the secondary desulfurization tower is a pressure vessel containing a second desulfurizing agent, and the second desulfurizing agent is fixed by a filter screen plate and ceramic balls. In certain embodiments of the invention, the secondary desulfurization tower is a generally commercially available stainless steel pressure vessel, filled with a second desulfurizing agent as desired. The filter screen plate and the porcelain ball are all generally sold in the market.
The device for treating the carbon dioxide feed gas further comprises a three-stage desulfurizing tower 7. The three-stage desulfurizing tower is used for third desulfurization of the compressed gas.
In some embodiments of the present invention, the third desulfurization tower is a pressure vessel containing a third desulfurizing agent, and the third desulfurizing agent is fixed by a filter screen plate and ceramic balls. In certain embodiments of the present invention, the tertiary desulfurization tower is a generally commercially available stainless steel pressure vessel, filled with a third desulfurizing agent as needed. The filter screen plate and the porcelain ball are all generally sold in the market.
The device for treating the carbon dioxide feed gas further comprises a preheater 8. And part of gas discharged by the three-stage desulfurization tower enters the preheater from a cold gas inlet of the preheater. The preheater is used for preheating part of the gas in the desulfurization gas.
In certain embodiments of the present invention, the preheater may be a generally commercially available preheater or heat exchanger. Specifically, the heat exchanger may be a heat exchanger manufactured by Shandong Haemai mechanical manufacturing Co.
In certain embodiments of the present invention, the means for processing the carbon dioxide feed gas further comprises a water cooler. And the gas inlet of the water cooling gas is connected with the cooling gas outlet of the preheater. And the mixed gas after heat exchange enters a water cooler to be cooled and dewatered, so that carbon dioxide gas with higher purity is obtained. And the gas discharged from the cold gas outlet of the preheater is high-purity carbon dioxide gas.
The device for treating the carbon dioxide raw gas further comprises an electric heater 9 for removing hydrocarbon. And the gas inlet of the electric heater for removing hydrocarbon is connected with the hot gas outlet of the preheater. The temperature of the carbon dioxide raw material gas discharged from the preheater does not reach the reaction temperature of the dealkylation tower, and the hydrocarbons cannot be effectively removed, so that the temperature of the preheated carbon dioxide raw material gas needs to be raised again by the electric heater.
In certain embodiments of the invention, the electric heater for hydrocarbon removal is generally commercially available.
The apparatus for treating a carbon dioxide raw gas according to the present invention further comprises a dealkylation reactor 10. The de-hydrocarbon reactor is used for the reaction of oxygen and hydrocarbons in the sweet gas. The gas inlet of the de-hydrocarbon reactor is connected with the gas outlet of the de-hydrocarbon electric heater; the gas outlet of the de-hydrocarbon reactor is connected with the hot gas inlet of the preheater.
In certain embodiments of the present invention, the de-hydrocarbon reactor may be a generally commercially available de-hydrocarbon reactor.
The apparatus for treating a carbon dioxide raw material gas further comprises a drying tower 11. And the residual gas discharged by the third-stage desulfurizing tower enters a drying tower to be dried.
In certain embodiments of the present invention, the drying tower may be a generally commercially available drying tower and associated equipment.
The apparatus for processing a carbon dioxide raw gas according to the present invention further includes a liquefier 12. The liquefier is used for liquefying the dried gas. The gas inlet of the liquefier is connected with the gas outlet of the drying tower.
In certain embodiments of the present invention, the liquefier may be a commonly available liquefier.
The device for treating the carbon dioxide raw material gas further comprises an intermediate storage tank 13. The inlet of the intermediate storage tank is connected with the outlet of the liquefier; the outlet of the intermediate storage tank is connected with the recycled carbon dioxide gas inlet with high hydrogen content of the gas mixing device.
In some embodiments of the present invention, the intermediate storage tank is a liquid carbon dioxide storage tank, which may be a generally commercially available cryogenic pressure storage tank.
In order to further illustrate the present invention, the following will describe the method and apparatus for treating carbon dioxide feed gas in detail with reference to the examples, but they should not be construed as limiting the scope of the present invention.
Example 1
The volume concentration of carbon dioxide in the feed gas is 98%, impurities in the feed gas comprise sulfur, hydrogen, alkane, benzene, olefin and alcohol hydrocarbon, and the volume content of the hydrogen in the feed gas is 0.7%; the water content in the feed gas is 3000 ppm;
in the carbon dioxide gas with high hydrogen content, the volume content of hydrogen is 7%.
The carbon dioxide feed gas treatment plant shown in figure 2 was used to treat the feed gas:
1) mixing the raw material gas, oxygen and carbon dioxide gas with high hydrogen content, wherein the volume content of hydrogen in the obtained mixed gas is increased by 1.5 percent compared with the volume content of hydrogen in the raw material gas;
2) sequentially performing primary compression (the gas pressure after the primary compression is 0.3MPa), secondary compression (the gas pressure after the secondary compression is 0.9MPa) and tertiary compression (the gas pressure after the tertiary compression is 2.3MPa) on the mixed gas to obtain compressed gas;
3) subjecting the compressed gas to a first desulfurizing agent (composite iron oxide produced by Zhengzhou Yingke environmental protection materials Co., Ltd.) at 40 deg.C to obtain H2S is converted into elemental sulfur and solid sulfide; the volume space velocity of the first desulfurizing agent is 1000/h;
then under the action of second desulfurizing agent (ferric oxide) and steam at 80 deg.C converting organic sulfur into inorganic sulfur H2S; the volume space velocity of the second desulfurizing agent is 1000/h;
finally removing inorganic sulfur H under the action of a third desulfurizer (active carbon) at 50 DEG C2S, obtaining desulfurized gas (the sulfide concentration of the desulfurized gas is 0.01 ppm); the volume space velocity of the third desulfurizing agent is 1000/h;
4) to obtain the desulfurized gasAfter the desulfurization, part of the desulfurization gas (the volume ratio of the part of the desulfurization gas to the desulfurization gas is 70%) is preheated to 260 ℃ (the load of an electric heater required for preheating the part of the desulfurization gas to 260 ℃) is 30%, and oxygen is added into a catalyst (RE-Pd-Pt/Al)2O3The catalyst is used for reacting at 260 ℃ for 2.5s under the action of 0.1% by mass of palladium, 0.05% by mass of platinum and 0.001% by mass of rare earth elements to generate a mixed gas (namely, a treated gas, wherein the total hydrocarbon content in the mixed gas of high-temperature carbon dioxide and water vapor is reduced to 10ppm), the mixed gas of high-temperature carbon dioxide and water vapor provides preheating energy for part of gases in the desulfurization gas, the temperature of the mixed gas of high-temperature carbon dioxide and water vapor is reduced, the mixed gas enters a water cooler for cooling and dewatering, a gas discharged from a cold air outlet of the preheater is a high-purity carbon dioxide gas, the concentration of the carbon dioxide is more than 99.99%, and the total hydrocarbon content is 10ppm, and the high-purity carbon dioxide gas enters a subsequent treatment system;
and (3) drying the residual gas in the desulfurized gas (the residual gas in the desulfurized gas accounts for 30% of the volume of the desulfurized gas) (the water content of the dried gas is 3ppm), liquefying, evaporating and concentrating to obtain the carbon dioxide gas with high hydrogen content (the volume content of hydrogen is 7%), and recycling the carbon dioxide gas in the step 1).
The invention utilizes the reaction heat of hydrogen to improve the temperature rise of the bed layer, thereby reducing the load of an electric heater in front of the dealkylation reactor; the method for efficiently desulfurizing reduces the concentration of total sulfur (the total sulfur concentration is reduced to be less than 0.01ppm) before the hydrocarbon is removed, prolongs the service life of the hydrocarbon removal catalyst, and simultaneously reduces the risk of sulfide stress corrosion of a pre-heater of the hydrocarbon removal. Under normal airspeed, every time 1% (volume percentage) of hydrogen is added, the temperature of the bed layer of the dehydrocarbon reactor rises to about 40 ℃, in the method, part of the raw material gas after the raw material gas is desulfurized does not enter a dehydrocarbon procedure but enters a drying procedure to be directly liquefied and enters an intermediate storage tank after water is removed, and the boiling point of the hydrogen is far lower than that of CO2The hydrogen is subjected to flash evaporation concentration in an intermediate storage tank, and the flash evaporation gas contains about 7 percent of hydrogen. Mixing flash evaporation gas into raw material according to a certain proportionIn gas, the proportion of hydrogen in the raw material gas is improved by about 1.5 percent, the temperature of an outlet of an electric heater in front of the dealkylation tower is reduced from about 320 ℃ to about 260 ℃ before, and then the requirement of the energy consumption of the temperature rise of a dealkylation bed layer can be met, and the load of the electric heater is reduced from 60-100 percent before to 30-0 percent, so the energy consumption is reduced. The high-efficiency desulfurization technology adopts a three-stage fine desulfurization process, and the sulfur and H from the compression process contain a small amount of sulfur2Removing H from carbon dioxide raw material gas containing impurities such as alkane, benzene, olefin, alcohol hydrocarbon and the like through a primary desulfurizing tower2S, then the sulfur is fed into a secondary desulfurization tower to convert organic sulfur into inorganic sulfur H which is easy to remove2S, then entering a three-stage desulfurizing tower to remove H2S。
In the application of the technical scheme, the load of the electric heater in front of the dealkylation tower is reduced by 150kW per hour, and 120 ten thousand kW.h can be saved all the year round; after the total sulfur of the feed gas is reduced to be less than 0.01ppm after three-stage high-efficiency desulfurization, the service life of the dealkylation catalyst reaches 6 years, and the condition that the sulfide stress corrosion cracking does not occur in the dealkylation preheater.
The concentration of carbon dioxide in the treated gas obtained by the treatment method provided by the invention is higher, and the concentration of impurities is lower.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for treating carbon dioxide raw gas comprises the following steps:
A) mixing raw material gas, oxygen and carbon dioxide gas with high hydrogen content, wherein the volume content of hydrogen in the obtained mixed gas is increased by 1.3-1.7% compared with the volume content of hydrogen in the raw material gas;
B) compressing the mixed gas to obtain compressed gas with the pressure of 2.1-2.5 MPa;
C) removing H from the compressed gas under the action of a first desulfurizing agent2S；
Converting organic sulfur into inorganic sulfur under the action of a second desulfurizer;
finally, removing inorganic sulfur under the action of a third desulfurizer to obtain desulfurized gas;
D) preheating part of the desulfurized gas to 255-265 ℃, reacting with oxygen under the action of a catalyst to generate mixed gas containing high-temperature carbon dioxide and water vapor, and performing heat exchange with part of the gas in the desulfurized gas;
and (4) drying, liquefying and evaporating and concentrating residual gas in the desulfurized gas to obtain carbon dioxide gas with high hydrogen content, and reusing the carbon dioxide gas in the step A).
2. The treatment process according to claim 1, wherein in step a), the volume concentration of carbon dioxide in the feed gas is > 90%;
impurities in the feed gas include sulfur, hydrogen, alkanes, benzene, alkenes, and alcohol hydrocarbons;
the volume content of hydrogen in the feed gas is 0.3-0.7%;
the water content in the feed gas is 2800-3200 ppm;
in the carbon dioxide gas with high hydrogen content, the volume content of hydrogen is 6-8%.
3. The process of claim 1, wherein in step B), said compression comprises a first stage compression, a second stage compression and a third stage compression;
the gas pressure after the first-stage compression is 0.1-0.3 MPa;
and the gas pressure after the secondary compression is 0.3-1.1 MPa.
4. The process according to claim 1, characterized in that, in step C), said first desulfurization agent comprises complex iron oxide; the volume space velocity of the first desulfurizing agent is 1000/h-1500/h;
the second desulfurizing agent comprises ferric oxide and water vapor; the volume space velocity of the second desulfurizing agent is 1000/h-1500/h;
the third desulfurizing agent comprises activated carbon; the volume space velocity of the third desulfurizing agent is 1000/h-1500/h.
5. The process according to claim 1, characterized in that, in step C), the compressed gas is subjected to H removal by the action of a first desulfurizing agent2The temperature of S is 25-70 ℃;
conversion of organic sulfur to H2The temperature of S is 75-85 ℃;
removing H under the action of a third desulfurizing agent2The temperature of S is 30-80 ℃;
the sulfide concentration of the desulfurization gas is not higher than 0.01 ppm.
6. The treatment method according to claim 1, wherein in the step D), the load of an electric heater required for preheating part of the gas in the desulfurization gas to 255-265 ℃ is 0-30%;
the catalyst comprises RE-Pd-Pt/Al doped with rare earth elements2O3A catalyst;
the reaction temperature is 255-265 ℃.
7. The treatment method according to claim 1, wherein in the step D), the partial gas in the desulfurization gas accounts for 70-90% of the volume ratio of the desulfurization gas;
the total hydrocarbon content in the mixed gas of the high-temperature carbon dioxide and the water vapor is not higher than 10 ppm.
8. The treatment method according to claim 1, wherein in the step D), the residual gas in the desulfurization gas accounts for 10-30% by volume of the desulfurization gas;
the water content of the dried gas is below 5 ppm;
in the carbon dioxide gas with high hydrogen content, the volume content of hydrogen is 6-8%.
9. A plant for treating a carbon dioxide feed gas, comprising:
a gas mixing device;
the gas compression device is connected with the gas outlet of the gas mixing device;
the first-stage desulfurizing tower is connected with a gas outlet of the gas compression device;
the second-stage desulfurizing tower is connected with the gas outlet of the first-stage desulfurizing tower;
the third-stage desulfurizing tower is connected with the gas outlet of the second-stage desulfurizing tower;
part of gas discharged by the three-stage desulfurization tower enters the preheater from a cold gas inlet of the preheater;
a hydrocarbon-removing electric heater connected with the hot gas outlet of the preheater;
the de-hydrocarbon reactor is connected with the gas outlet of the de-hydrocarbon electric heater; the gas outlet of the dealkylation reactor is connected with the hot gas inlet of the preheater;
the residual gas discharged by the third-stage desulfurizing tower enters a drying tower;
a liquefier connected to the gas outlet of the drying tower;
an intermediate storage tank connected to the outlet of the liquefier; the outlet of the intermediate storage tank is connected with the recycled carbon dioxide gas inlet with high hydrogen content of the gas mixing device.
10. The process arrangement of claim 9, wherein the gas compression device comprises:
the primary compressor is connected with a gas outlet of the gas mixing device;
a secondary compressor connected to the gas outlet of the primary compressor;
the three-stage compressor is connected with a gas outlet of the two-stage compressor;
and a gas outlet of the third-stage compressor is connected with a gas inlet of the first-stage desulfurizing tower.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114768422A (en) * | 2022-04-24 | 2022-07-22 | 惠州凯美特气体有限公司 | Method and equipment for removing impurities by using gaseous carbon dioxide |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB889226A (en) * | 1959-06-15 | 1962-02-14 | Ici Ltd | Desulphurisation process |
| CN1594077A (en) * | 2004-07-05 | 2005-03-16 | 湖北省化学研究院 | Hydrocarbon trap method for carbon dioxide for foodstuff |
| CN107934963A (en) * | 2017-11-28 | 2018-04-20 | 西南化工研究设计院有限公司 | The preparation system and preparation method of a kind of food-class high-purity liquid CO 2 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB889226A (en) * | 1959-06-15 | 1962-02-14 | Ici Ltd | Desulphurisation process |
| CN1594077A (en) * | 2004-07-05 | 2005-03-16 | 湖北省化学研究院 | Hydrocarbon trap method for carbon dioxide for foodstuff |
| CN107934963A (en) * | 2017-11-28 | 2018-04-20 | 西南化工研究设计院有限公司 | The preparation system and preparation method of a kind of food-class high-purity liquid CO 2 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114768422A (en) * | 2022-04-24 | 2022-07-22 | 惠州凯美特气体有限公司 | Method and equipment for removing impurities by using gaseous carbon dioxide |
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