JP4213389B2 - Production, storage and utilization system for liquefied CO2 and dry ice and production, storage and utilization system for liquefied CO2 and hydrogen - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention uses exhaust heat from a chemical factory or the like to emit CO 2₂Gas, H₂CO for gas recovery and co-production reforming reactions₂Utilization of reaction heat in a reaction system with by-products and CO as a by-product₂With high yield recovery of gas and related to low environmental load and cold energy supply system such as low temperature logistics, food factory, chemical factory, etc.
  Using low-temperature exhaust heat and high-temperature exhaust heat, conversion to cold and high concentration CO₂Let the gas recover,
  High concentration CO₂Gas to CO₂Used as a refrigerant for liquefaction cycle, the cold heat is used as CO₂High pressure high temperature supercritical CO in liquefaction cycle₂Liquefied CO used as a cooling heat source for₂・ Dry ice production / storage / use system and liquefied CO₂・ Hydrogen production / storage / use systemToRelated.
[0002]
[Prior art]
  In recent years, from the viewpoint of global environmental problems, especially global warming prevention, effective use of low-temperature exhaust gas from factories, effective use of surplus night power, and CO₂There are calls for reduction and recovery of gas emissions into the atmosphere.
  CO₂In order to reduce the amount of CO2 emissions, energy conservation and thermal power plants and other CO₂CO emitted from facilities with large emissions₂It is necessary to collect the gas and not release it to the atmosphere.
  Recently, in large chemical factories and the like, cogeneration facilities equipped with electric power supply and heat supply have become widespread and waste heat is being collected. For example, a combined power generation cycle shown in FIG. 5 is used, a combined cycle in which a power generation facility 50 using a steam turbine 50a conventionally used for thermal power generation and a gas turbine power generation device 51 is used, and an exhaust heat boiler 52 is used. The steam 52a obtained in step 1 is sent to the steam turbine 50a so as to obtain auxiliary power, and the amount of extracted steam 50b from the steam turbine 50a is changed to form a thermoelectric variable system for efficient energy use. I am trying.
[0003]
  CO₂In order to reduce the amount of CO2 emissions, energy conservation and thermal power plants and other CO₂It is required that carbon dioxide forming a part of combustion exhaust gas discharged from a facility with a large discharge amount is concentrated and separated and recovered as gaseous, liquid, or solid dry ice. In response to this requirement, Japanese Patent Application Laid-Open No. 2000-24454 discloses a proposal “method and apparatus for treating flue gas”.
  The schematic configuration of the proposal will be described below with reference to FIG.
  This apparatus relates to a combustion exhaust gas treatment method and apparatus for separating and recovering carbon dioxide in combustion exhaust gas after solidifying it as dry ice using LNG cold heat.
[0004]
  The structure is composed of a moisture aggregating means 62 for aggregating moisture by cooling the moisture in the combustion exhaust gas 61 discharged from the boiler 60, and cooling the residual moisture in the combustion exhaust gas at a low temperature of −30 ° C. or lower to make the ice 63a. The solid gas that separates the solidified ice solidification device 63 and the carbon dioxide gas solidification device 64 from the carbon dioxide gas (dry ice) 65 in the combustion exhaust gas 61 from which moisture has been completely removed and the low temperature carbon dioxide free exhaust gas 66. A separator 67, a carbon dioxide gas liquefier 68 that pressurizes and liquefies the separated dry ice 65, and a liquefied CO₂The liquefied carbonic acid storage tank 70 that stores 69 and a heat exchanger (not shown) that liquefies the LNG to obtain cold energy are configured.
[0005]
  The above proposal is to effectively use the heat of vaporization of the LNG as a cold heat, solidified or separated moisture in the combustion exhaust gas as ice, and further solidified or liquefied the carbon dioxide gas in the combustion exhaust gas as dry ice. However, the use of fuel having such a large heat of vaporization is limited to a specific case, and there is a problem that cannot be applied when using general city gas.
[0006]
  Other than the above, CO in combustion exhaust gas₂As a method for separating a gas in a gaseous state, there is a proposal related to “a method for separating and collecting carbon dioxide” disclosed in Japanese Patent Laid-Open No. 10-59705.
  In this proposal, carbon dioxide gas contained in the mixed gas is reduced in energy consumption required for separation and recovery by a method including a membrane separation step and a cryogenic separation step. Have issues such as equipment scale-up and cost.
[0007]
  Next, as a dry ice manufacturing method, conventionally, liquefied CO is used.₂The self-depressurized flash system is used to phase-transform the liquid at −20 ° C. to the dry ice at −78.5 ° C. to collect fine particles of dry ice, but the yield is low.
[0008]
  As a means for solving the low yield, Japanese Patent Application Laid-Open No. 1-320213 discloses a new proposal for solving the problem.
  This proposal is more than a triple point (5.28 Kg / cm) into a solidified container which is a piston cylinder.²liquefied CO compressed to abs or higher pressure)₂Is continuously extracted.
  The conventional self-flush method was made to solve the low yield, and almost all of the liquefied carbon dioxide injected into the cylinder was solidified, and the solidified dry ice was continuously drawn into the holding mechanism. However, the cylinder wall and solidified liquefied CO₂There is a problem that it is difficult to set operating conditions.
[0009]
  Another proposal for solving the problems of the above proposal is disclosed in Japanese Patent Laid-Open No. 5-97419 as a proposal relating to a dry ice generation system.
  In this proposal, as shown in FIG. 7, the liquefied carbon dioxide gas reaches the liquefied carbon dioxide gas solidifying device 81 from the tank trolley 83 through the decompression cooler 84, the storage tank 85, etc., and the post-cutting cutting device 86 and the conveying device 86a. Then, the product is transferred to the ultra-low temperature warehouse 87 for supercooling the product dry ice.
  The path of the coolant circulation system S3 includes a coolant cooler 88, an ultra-low temperature warehouse 87 for product dry ice supercooling, a liquefied carbon dioxide solidifying device 81, a decompression cooler 84, a coolant receiver 89, and a coolant pump 90. On the other hand, the LNG cooling system S2 includes a path from the LNG source 91 to the coolant cooler 88 and the natural gas warmer 92.
  In the above configuration, the liquefied CO carried by the tank truck 83₂The liquefied coal (−20 ° C.) is cooled to −50 ° C. by the vacuum cooler 84 and stored in the storage tank 85, and 6 Kg / cm²It is introduced into the solidifying device 81 in a state of being pressurized to G or higher. The introduced liquefied carbon dioxide gas is further cooled by the solidifying device 81, and rod-shaped dry ice at -78.5 ° C. or lower is generated. The bar-shaped dry ice 81a is cut by a cutting device 86 and stored in a supercooling cryogenic warehouse 87.
[0010]
  On the other hand, regarding a carbon dioxide liquefying apparatus, a proposal relating to a high-yield carbon dioxide liquefying apparatus in which raw material carbon dioxide is not released to the outside is disclosed in JP-A-10-59706. The proposal is shown in FIG.
  A low pressure gas line 103 from a gas holder 101 for storing carbon dioxide gas is connected to a low pressure side suction port 104a of a carbon dioxide gas compressor 104 composed of a two-stage compressor via a water washing cylinder 102 for removing impurities in the carbon dioxide gas. The low-pressure side discharge port 104b of the compressor 104 is connected to the high-pressure side inlet 104c of the compressor via the deodorizing device 105 by the medium pressure gas line 106, and the discharge port 104d is connected to the dehumidifier 108 by the high-pressure gas line 107. And connected to a carbon dioxide gas inlet 109 a of the cooling device 109.
  The cooling device 109 condenses and liquefies the carbon dioxide gas from the high-pressure gas line 107, and condenses and liquefies the carbon dioxide gas by the refrigerant sent into the refrigerant coil 109c in the cooling device 109 from a refrigerator (not shown), for example. is doing.
  The other end of the high-pressure liquid line 110 having one end connected to the liquefied carbon dioxide outlet 109b of the cooling device 109 is connected to a liquefied carbon dioxide supply line 113 having an open / close valve 112 below the vacuum heat insulating tank 111 for storing the liquefied carbon dioxide. One end is connected.
  The other end of the return gas line 114 having one end facing the gas phase portion in the vacuum heat insulation tank 111 is connected to the low pressure side discharge port 104b of the compressor 104 and the intermediate pressure gas line 106 passing through the deodorizing device 105.
  With the above configuration, the carbon dioxide gas compressed by the compressor 104 is condensed and liquefied by the cooling device 109 to become liquefied carbon dioxide, which is sent to the vacuum heat insulation tank 111 and stored.
  When the gas phase pressure in the tank exceeds a predetermined value due to the liquefied carbon dioxide being fed into the tank, the carbon dioxide gas is recirculated to the suction side of the compressor via the return gas line by a signal from the pressure regulator 116, Eliminate waste.
[0011]
  Further, in the conventional dry ice production process including carbon dioxide liquefaction, as shown in FIG. 9, the cleaning process by the cleaning tower 121 and the desulfurization process by the desulfurizer 122 performed before the compression by the compressor 120 of carbon dioxide gas, after the compression The purification process performed by the purification tower 123 and the dehumidification process performed by the dehumidifier 124 are required (some of which are also found in the above proposal).₂Gas cooler 125, CO₂Supercooled supercritical CO by gas cooler 126 and supercooler 127₂And forming the supercritical CO₂High density supercritical gas close to the liquid of CO₂After being stored in the liquefaction tank 128, it is introduced into the dry ice press machine 130 through the pressure reducing valve 129, and the dry ice press machine generates dry ice at about -78.5 ° C.₂The gas is recirculated to the compressor 120 after passing through the heat exchanger of the supercooler 127.
  In the conventional dry ice production system, since the raw material is a crude gas, the equipment costs of the washing tower 121, the desulfurizer 122, the purification tower 123, and the dehumidifier 124 are required before and after compression as described above, and the raw material CO₂A low yield of 39.4% based on the crude gas.
  Therefore, there is a demand for realizing a high-yield dry ice production method with high energy saving and an apparatus therefor while keeping the facility cost low.
[0012]
  In particular, hydrogen energy is regarded as important as a new energy that suppresses the consumption of energy and substances and suppresses the emission of environmental pollutants, because it compensates for the disadvantages of natural energy such as wind power, solar dilution, and temporal variability. In particular, in order to make it possible to use a large amount of the hydrogen energy, it is strongly required to implement measures for efficiently recovering carbon dioxide in which 25% of the hydrogen energy is generated as a by-product by the reforming reaction.
[0013]
[Problems to be solved by the invention]
  The present invention has been made in view of the above problems,
  Using low-temperature exhaust heat and high-temperature exhaust heat, conversion to cold and high concentration CO₂In addition to allowing gas to be collected and discharged, CO₂Recovery of reaction heat and CO in reaction systems with by-products₂Enables high yield recovery of gas,
  Liquefied CO₂・ Dry ice manufacturing, storage and utilization system and CO₂・ Hydrogen production / storage / use systemOfIt is for the purpose of provision.
[0014]
[Means for Solving the Problems]
  Therefore, the liquefied CO using the factory waste heat which is the first invention of the present invention.₂・ In the production, storage and use system of dry ice,Etc.Discharge50-200 ° CThe cold heat obtained from a chemical heat pump that operates using low-temperature exhaust heat produces CO₂Activate the gas cooler, CO₂The supercritical state of the high-temperature and high-pressure refrigerant in the liquefaction cycle is formed, and the supercritical CO₂Through a two-phase flow expanderLiquidCO₂ And CO₂Separated into gas, the former liquefied CO₂The dry ice is obtained by cooling theCO₂Gas to CO₂It is characterized by being configured to be reused as a refrigerant for a liquefaction cycle.
[0015]
  The invention uses the low-temperature exhaust heat (about 50 to 100 ° C.) that forms the factory exhaust heat, which is the object of the present invention, and the high-temperature exhaust heat (about 500 ° C.) due to the bleed steam at night to convert into cold heat. And high concentration CO₂Let the gas be collected and discharged separately,
  The recovered high concentration CO₂Gas to CO₂Used as a refrigerant for liquefaction cycle, the cold heat is used as CO₂CO via gas cooler₂Used to cool high temperature gas in liquefaction cycle, supercritical CO₂The above-described cold heat and high concentration CO₂The gas can be supplied in a balanced manner and the efficient use of highly efficient exhaust heat is achieved.
[0016]
  The liquefied CO₂To obtain the high concentration CO₂CO2 compressor using gas as refrigerant₂CO including gas cooler, gas-liquid separation and decompression means, etc.₂A liquefaction cycle is formed, and the cold heat causes the CO₂Activate the gas cooler and place the high-temperature and high-pressure refrigerant from the compressor in the supercritical state.₂The liquid phase and the gas phase are mixed and constantly transformed to maintain a state where no phase boundary exists. CO in its supercritical state₂Is separated into a liquid phase and a gas phase by interposing a two-phase flow expander which is a gas-liquid separation decompression means, and liquefied CO₂As a result, dry ice is obtained, and cold storage and use are possible.
  Note that the low-pressure low-temperature CO formed during the gas-liquid separation and decompression₂The gas is the high concentration CO₂Inhaled into the compressor along with gas, CO₂Reused in liquefaction cycle.
[0017]
  The liquefied CO of the present invention₂-It is preferable that the two-phase flow expander in the dry ice production / storage / use system has an adiabatic expansion function that enables power recovery by a directly connected generator.
[0018]
  The invention describes the structure of the two-phase flow expander used in the present invention, and the CO in the supercritical state is described.₂A two-phase flow expander that separates the liquid into two phases, the liquid phase and the gas phase, is formed by an expansion turbine.₂In order to adiabatic expansion, the expansion medium can be cooled to about −50 ° C.₂While improving the recovery and fixing rate of low-temperature, low-pressure low-pressure CO₂The amount of gas generated can be reduced.
  When the expander is in operation, energy is saved by operating a directly connected generator so that power can be recovered.
[0019]
  The liquefied CO of the present invention₂-The two-phase flow expander in the dry ice production, storage and utilization system is equipped with supercritical CO at the inlet of the expander.₂The structure which introduce | transduces is preferable.
[0020]
  The invention relates to a supercritical CO that flows in during the operation of the two-phase flow expander.₂In which the inflowing CO₂Since the supercritical state is formed and maintained by the cold heat, the vicinity of the expander inlet is a mixture of gas phase and liquid phase.₂Since the molecules are in a state of intense exercise, the inhalation resistance is small, and after inhalation, the molecules diffuse violently to increase the inhalation diffusion efficiency.
[0021]
  The second invention of the present inventionIs liquefied CO using factory waste heat ₂ ・ Production and storage of hydrogenIn the usage system,
  High concentration, high purity CO via steam reforming means of fuel using surplus steam when using nighttime power₂Gas and H₂It is configured to obtain gas,
  Reaction heat and factory during the reformingEtc.Discharge50-200 ° CThe cold heat obtained from a chemical heat pump that operates using low-temperature exhaust heat produces CO₂Activate the gas cooler, CO₂Forming a supercritical state of the high-temperature and high-pressure refrigerant in the liquefaction cycle,₂Through a two-phase flow expanderLiquidCO₂ And CO₂Separated into gas, the former liquefied CO₂The dry ice is obtained by cooling the latterCO₂Gas to CO₂It is characterized by being configured to be reused as a refrigerant for a liquefaction cycle.
[0022]
  The above invention is the liquefied CO of the second invention of the present invention.₂・ It describes the production, storage, and utilization system of hydrogen gas.
  For the high-temperature exhaust heat of the factory exhaust heat, excess steam (about 500 ° C) during night operation of the steam turbine driven by the exhaust heat boiler or the reaction heat of the reforming reaction is used.₂Activate the gas cooler and CO₂Form liquefaction cycle, liquefied CO₂, Enables the production, storage and use of dry ice and the CO₂The high concentration CO deposited on the methane gas by steam reforming means₂The use of gas and the production, storage, and utilization of hydrogen gas.
[0023]
  The liquefied CO of the present invention₂・ Dry ice production / storage / use system and liquefied CO₂・ CO in hydrogen production, storage, and utilization systems₂The working medium used for the liquefaction cycle is
  By exhaust gas and waste heat from factory waste heat boilerHigh concentration CO obtained through chemical absorption method₂A configuration using gas is preferred.
[0024]
  The invention is based on the liquefied CO of the present invention.₂・ Dry ice production / storage / use system and liquefied CO₂・ CO in hydrogen production, storage, and utilization systems₂It describes the refrigerant used in the liquefaction cycle,
  In this case, alkanolamine is contacted with the exhaust gas, CO₂After being absorbed into water and CO through high-temperature steam.₂Obtained by chemical absorption method that decomposes into CO₂Is used.
[0025]
[0026]
[0027]
[0028]
[0029]
[0030]
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. .
  FIG. 1 shows liquefied CO using factory waste heat of the present invention.₂A block diagram showing a schematic configuration of a dry ice / hydrogen production / storage / utilization system. FIG.₂It is a Mollier diagram of a liquefaction cycle.
  FIG. 3 is a block diagram showing a schematic configuration of the dry ice production apparatus of the present invention, and FIG.₂It is a Mollier diagram of a liquefaction cycle.
[0042]
  As shown in FIG. 1, liquefied CO using the factory waste heat of the present invention.₂A dry ice / hydrogen production / storage / utilization system includes a chemical heat pump absorption refrigerator 10, a fuel steam reforming unit 20, a chemical absorption unit 23, attached to a heat supply unit 30 of a chemical factory, etc. CO₂It comprises the liquefaction cycle 11.
[0043]
  The heat supply unit 30 is a gas turbine (not shown).5The waste heat boiler 52 that discharges the exhaust gas 52b (approximately 50 to 100 ° C.) that is driven by the supply of the waste heat of FIG. 5 and the steam turbine 50a that is operated by the drive steam 52a from the boiler 52, the steam turbine 50a From the exhaust gas boiler 52b (150 to 200 ° C.) and the exhaust gas 52b are supplied to the chemical heat pump 10 as low-temperature exhaust gas during the daytime, and from the exhaust gas boiler 52, driving steam 52a (about 500 ° C.) is surplus during night operation. Is supplied to the fuel steam reforming means 20 and the chemical absorption means 23, which will be described later, as high-temperature exhaust gas.₂Gas 21 and hydrogen gas 22 are obtained.
  The chemical heat pump 10 uses an absorption refrigerator and obtains cold heat of about 0 to 5 ° C.
[0044]
  CO₂The liquefaction cycle 11 includes a compressor 12, a gas cooler 13, a two-phase flow expander 14, and a gas / liquid separator 15. The liquefaction cycle 11 has a high concentration and a high concentration recovered by the steam reforming unit 20 and the chemical absorption unit 23. Purity CO₂CO₂To form a high-pressure and high-temperature refrigerant 12a by depressurizing the superheated CO2 from the high-pressure and high-temperature refrigerant 12a through the cold heat 10a.₂To get.
  Next, CO was further supercooled by the cold and continuously maintained in a supercritical state at about 10 ° C.₂The gas 13a is separated and adiabatically expanded into a gas-liquid two-phase by a two-phase flow expander 14.
  The two-phase flow expander 14 is formed by an expansion turbine, and CO2 is expanded during expansion.₂The adiabatic medium can be cooled to about −50 ° C.₂While improving the recovery and fixing rate of low-temperature, low-pressure low-pressure CO₂The amount of gas generated can be reduced, and the power generator G connected directly can be operated to recover the power.
[0045]
  Thus, the CO flowing into the expander 14₂Since the supercritical state is maintained and it is placed in a vigorous motion state where the gas phase and the liquid phase are mixed, the suction resistance is small, and after the inhalation, it diffuses violently and adiabatic expansion makes it into two phases of the gas phase and the liquid phase While being separated, it is cooled to about −50 ° C. and introduced into the gas-liquid separator 15 where liquid phase liquefied carbon dioxide 16 is stored in the lower part. Re-vaporized low-temperature low-pressure CO separated at the top₂The gas 15a is sent to the compressor 12 with the high concentration and high purity CO.₂The gas 21 is sucked and compressed again.
[0046]
  Further, the liquefied carbon dioxide 16 generates dry ice 17 and can be used for cold storage, low-temperature logistics storage (non-fluorocarbon cold storage), process cooling / air conditioning for food factories, cooling for chemical factories, and the like.
[0047]
  FIG. 2 shows the CO of FIG.₂A Mollier diagram of the liquefaction cycle is shown.
  As shown in the figure, at point A, high concentration, high purity CO₂21 starts suction compression with the compressor 12. Inhalation CO₂The gas is adiabatically compressed along the isentropic line and CO at point B₂It is compressed to a critical pressure of 7.83 MPa or more to form a supercritical high temperature / high pressure refrigerant 12a. Next, the high-temperature and high-pressure refrigerant 12a is cooled by the gas cooler 13, is cooled below the critical point C, and continues in a supercritical state up to about 20 ° C. Next, at point D, the gas-liquid two-phase separation and adiabatic expansion by the two-phase flow expander 14 lead to point E, where liquefied CO₂And low temperature low pressure CO₂Separated into gas 15b.
[0048]
  As shown in FIG. 1, the fuel steam reforming means 20 adds a driving steam 52 a output from the exhaust gas boiler 52 to the methane 20 a to add hydrogen gas 22 and a high-concentration, high-purity CO 2.₂In addition, the alkanolamine 23a is reacted with the exhaust gas 52b by the chemical absorption means 23 so that the concentration of CO2 is higher than that of the exhaust gas 52b.₂The gas 21 is separated and recovered, and the CO₂Photosynthesis CO in addition to supplying to the liquefaction cycle 11₂Various uses are possible.
[0049]
  In FIG.IsThe block diagram which shows schematic structure of a rye ice manufacturing apparatus is shown. As shown in the figure, this dry ice production device
  Compressor 12, water cooler 26, CO₂Gas cooler 27, supercooler 28, high pressure CO₂Liquefaction tank 29 and low pressure CO₂Liquefaction tank 37 and the low pressure CO₂Liquefaction tank and high-pressure CO upstream₂CO comprising a high stage two-phase flow expander 31 provided between liquefaction tanks₂A liquefaction cycle 32;
  Low pressure CO₂It comprises a dry ice production unit 35 comprising a low-stage two-phase flow expander 33 and a dry ice press machine 34 provided downstream of the liquefaction tank.
[0050]
  Raw material CO used in the past₂Instead of crude gas, high-concentration, high-purity CO by co-emission of hydrogen gas by-product (25% of hydrogen gas) by steam reforming₂It is related to dry ice production equipment corresponding to the case of using gas,
  Conventional CO₂Eliminates the need for washing treatment by a washing tower and desulfurization treatment by a desulfurizer before compression for pretreatment, and purification treatment by a purification tower to be performed after compression, and dehumidification treatment by a dehumidifier, which are required when using crude gas. And after compression, high pressure and high temperature CO₂A water cooler 26 provided with a cooling tower 26a for cooling gas, and a CO provided with a chemical heat pump (CHP) 27a operated by exhaust heat of the co-production.₂A gas cooler 27 and a supercooler 28 are provided.
  The cooling source of the supercooler 28 includes a low-temperature CO of about −75 ° C. separated by a low-stage two-phase flow expander 33 described later.₂Use gas.
[0051]
  With the above configuration, COPRO emission CO introduced at point A on the Mollier diagram of FIG.₂The gas (high concentration and high purity) is adiabatically compressed along the isentropic line by the compressor 12 and compressed to a critical pressure of 7.83 MPa or more at the point B to form a supercritical high temperature and high pressure refrigerant 12a. Next, the high-temperature and high-pressure refrigerant 12a is composed of a water cooler 26, CO₂It is cooled by the gas cooler 27 and the supercooler 28, and the supercooling supercritical state is continued to the critical point C or lower. Next, high pressure CO at point D₂After passing through the liquefaction tank 29, it is separated into gas-liquid two phases by adiabatic expansion by the high-stage two-phase flow expander 31, and at point E, the low-pressure CO₂Introduced into the liquefaction tank 37 and above the triple point pressure (5.28 Kg / cm²abs) of 5.3 kg / cm²The separated low pressure CO at -56 ° C₂Gas 30a is the low-pressure CO₂Through the reflux path provided in the upper part of the liquefaction tank 37, it is introduced and refluxed to the intermediate port of the compressor 12 via the point A.₂A liquefaction cycle 32 is formed.
[0052]
  Low pressure CO₂Liquefied CO stored and held in the liquefaction tank 37 at a pressure higher than the triple point pressure₂Is reduced in pressure by a low-stage two-phase expander 33 at point F and solidified by a dry ice press machine 34 to produce dry ice 36 at about -78.5 ° C.₂The gas 34a passes through the heat exchanger of the supercooler 28 and is then recirculated to the compressor 12 at low temperature CO.₂Reflux as gas.
  With the above configuration, crude CO₂Compared to conventional dry ice systems that use gas as a raw material, the equipment for washing towers, desulfurizers, refining towers, and dehumidifiers used before and after compression is not necessary, and the equipment cost can be reduced.₂As for the gas recovery rate, a high yield of 51.7% can be raised compared with the conventional low yield of 39.4%, and the energy saving rate also shows a value of about 50% or more.
  The high-stage and low-stage two-phase flow expanders 31, 33 are directly connected to a generator G so that power can be recovered.
[0053]
【The invention's effect】
  With the above configuration, the present invention has the following effects.
  Using low-temperature exhaust heat and high-temperature exhaust heat, conversion to cold and high concentration CO₂Since the gas is collected and discharged, it is possible to perform an operation following the fluctuation of the load, and the factory exhaust heat can be divided into high and low temperatures and effectively used as appropriate.
  The recovered CO₂For gas liquefaction, CO₂By using a liquefaction cycle, the cold and a two-phase flow expander, the supercritical CO₂Is efficiently separated into a liquid phase and a liquid phase under reduced pressure to reduce liquefied CO₂Enables the production of dry ice and enables the use of cold storageYes.
[Brief description of the drawings]
FIG. 1 Liquefied CO using factory waste heat of the present invention₂FIG. 2 is a block diagram showing a schematic configuration of a dry ice / hydrogen production / storage / use system.
FIG. 2 shows CO in FIG.₂It is a Mollier diagram of a liquefaction cycle.
[Fig. 3]DoIt is a block diagram which shows the schematic structure of a rye ice manufacturing apparatus.
FIG. 4 CO in FIG.₂It is a Mollier diagram of a liquefaction cycle.
FIG. 5 is a diagram showing a combined basic system of a gas turbine.
FIG. 6 is a block diagram showing an embodiment of a conventional combustion gas processing method.
FIG. 7 is a diagram showing a schematic configuration of a conventional dry ice manufacturing apparatus.
FIG. 8 is a diagram showing a schematic configuration of a conventional carbon dioxide liquefaction apparatus.
FIG. 9 shows conventional CO₂It is a block diagram which shows the schematic structure of the dry ice manufacturing apparatus in the case of using crude gas.
[Explanation of symbols]
  10 Chemical heat pump
  11 CO₂Liquefaction cycle
  12 Compressor
  13, 27 Gas cooler
  14 Two-phase flow expander
  15 Gas-liquid separator
  16 Liquefied carbon dioxide
  17, 36 Dry ice
  20 Fuel steam reforming means
  21 High concentration CO₂gas
  22 Hydrogen gas
  23 Chemical absorption means
  26 Water cooler
  28 Supercooler
  29 High pressure CO₂Liquefaction tank
  30 Heat supply section
  30a Low pressure CO₂gas
  31 High-stage two-phase flow expander
  32 CO₂Liquefaction cycle
  33 Low-stage two-phase flow expander
  34 Dry ice press machine
  34a Low temperature CO₂gas
  35 Dry ice generator
  37 Low pressure CO₂Liquefaction tank

Claims (5)

In the production, storage, and utilization system of liquefied CO ₂ and dry ice using factory waste heat,
The CO ₂ gas cooler is operated by the cold heat obtained from the chemical heat pump that operates using low-temperature exhaust heat of 50 to 200 ° C. discharged from factories, etc., and the supercritical state of the high-temperature and high-pressure refrigerant in the CO ₂ liquefaction cycle is formed. , supercritical CO ₂ is separated into liquefied CO ₂ and C _{O 2} gas through the two-phase flow expander, wherein with obtaining a dry ice the latter C _{O 2} gas by cooling the former liquefied CO ₂ A system for producing, storing and utilizing liquefied CO ₂ / dry ice, characterized in that it is configured to be reused as a refrigerant for a CO ₂ liquefaction cycle. The system for producing, storing and using liquefied CO ₂ / dry ice according to claim 1, wherein the two-phase flow expander is configured to have an adiabatic expansion function that enables power recovery by a directly connected generator. The liquefied CO ₂ / dry ice production / storage / utilization system according to claim 1, wherein the two-phase flow expander is configured to introduce supercritical CO ₂ at an inlet of the expander. In the production, storage, and utilization system of liquefied CO ₂ and hydrogen using factory waste heat,
High concentration through a steam reforming unit of the fuel by using the excess steam during the night power use, with a configuration to obtain a high-purity CO ₂ gas and H ₂ gas,
The CO ₂ gas cooler is operated by the cold heat obtained from the chemical heat pump that operates using the heat of reaction and the low-temperature exhaust heat of 50 to 200 ° C. discharged from the factory during the reforming, and the high temperature of the CO ₂ liquefaction cycle to form a supercritical state of high-pressure refrigerant, the supercritical CO ₂ is separated into liquefied CO ₂ and C O ₂ gas through the two-phase flow expander, to give the dry ice by cooling the former liquefied CO ₂ Te, liquefied CO _2, hydrogen production, storage and utilization system, characterized in that the latter C O ₂ gas was configured to reuse the refrigerant of the CO ₂ liquefaction cycles. Working medium used in the CO ₂ liquefaction cycle, claim, characterized in that the configuration using the C O ₂ gas obtained through the chemical absorption by the exhaust gas and the exhaust heat from factories waste heat boiler 1 The production / storage / use system of liquefied CO ₂ / dry ice according to claim 4, and the production / storage of liquefied CO ₂ / hydrogen according to claim 4. Usage system.

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