WO2022095691A1 - 一种煤基富甲烷合成气深冷分离制lng的工艺与系统 - Google Patents

一种煤基富甲烷合成气深冷分离制lng的工艺与系统 Download PDF

Info

Publication number
WO2022095691A1
WO2022095691A1 PCT/CN2021/124579 CN2021124579W WO2022095691A1 WO 2022095691 A1 WO2022095691 A1 WO 2022095691A1 CN 2021124579 W CN2021124579 W CN 2021124579W WO 2022095691 A1 WO2022095691 A1 WO 2022095691A1
Authority
WO
WIPO (PCT)
Prior art keywords
cryogenic
heat exchanger
gas
tower
nitrogen
Prior art date
Application number
PCT/CN2021/124579
Other languages
English (en)
French (fr)
Inventor
杨思宇
陈建军
李丹
钱宇
Original Assignee
华南理工大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华南理工大学 filed Critical 华南理工大学
Publication of WO2022095691A1 publication Critical patent/WO2022095691A1/zh

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0223—H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/0605—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the feed stream
    • F25J3/061—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0271—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of H2/CO mixtures, i.e. of synthesis gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
    • F25J3/0695—Start-up or control of the process; Details of the apparatus used
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/74—Refluxing the column with at least a part of the partially condensed overhead gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/04—Recovery of liquid products
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2260/00—Coupling of processes or apparatus to other units; Integrated schemes
    • F25J2260/02—Integration in an installation for exchanging heat, e.g. for waste heat recovery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/12—External refrigeration with liquid vaporising loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/14—External refrigeration with work-producing gas expansion loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/18—External refrigeration with incorporated cascade loop
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/42—Quasi-closed internal or closed external nitrogen refrigeration cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/66—Closed external refrigeration cycle with multi component refrigerant [MCR], e.g. mixture of hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/902—Details about the refrigeration cycle used, e.g. composition of refrigerant, arrangement of compressors or cascade, make up sources, use of reflux exchangers etc.
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/906—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by heat driven absorption chillers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/34—Details about subcooling of liquids

Definitions

  • the invention belongs to the field of coal chemical industry, and in particular relates to a process and system for producing LNG by cryogenic separation of coal-based methane-rich synthesis gas.
  • coal-to-methanol is of practical significance to adjust the national energy structure and reduce the dependence of the olefin industry on crude oil imports.
  • coal-to-methanol and other chemical products are a rapidly developing and promising industry.
  • the cryogenic separation of crude synthesis gas is of great significance to the quality of coal chemical products.
  • the LNG (natural gas) separated in this process is a clean and safe high-quality energy source, which is widely used in commercial, civil, chemical and power generation industries. With the increasing pressure, the gap between supply and demand in the natural gas market is large, and the import volume of natural gas is large. The separated LNG can also meet the demand of the natural gas market and reduce the import of natural gas.
  • the whole process is divided into three parts, namely nitrogen compression refrigeration, crude synthesis gas cryogenic separation, and mixed refrigerant compression refrigeration.
  • Cryogenic separation of crude synthesis gas The crude synthesis gas enters the cryogenic heat exchanger to cool down and cryogenically through the compressor and water cooler, and the synthesis gas exiting the cryogenic heat exchanger enters the crude synthesis gas gas-liquid separation tank for gas-liquid separation.
  • the pressure is reduced and cooled by the expander, and the liquid phase is passed through the throttle valve.
  • the crude syngas exiting the expander and the throttle valve simultaneously enters the methane cryogenic separation tower for separation, the syngas at the top outlet of the tower and the natural gas at the tower kettle exit enter the LNG cryocooler, the exit natural gas is cooled and enters the next section, and the LNG exits
  • the syngas from the cryocooler enters the cryogenic heat exchanger through the compressor for heat exchange to recover cold capacity, and then enters the next section.
  • Nitrogen compression refrigeration nitrogen is compressed and cooled in two stages, the cooled nitrogen is cooled by a nitrogen pre-cooler, and then enters the cryogenic heat exchanger for cooling and cryogenic cooling, and the nitrogen exiting the cryogenic heat exchanger enters the nitrogen primary gas-liquid separation tank
  • the gas-liquid separation is carried out, the gas phase is depressurized by the expander, the liquid phase is depressurized by the throttle valve, and the temperature is further reduced.
  • the depressurized gas phase and liquid phase then enter the nitrogen primary gas-liquid separation tank for gas-liquid separation, and the liquid phase enters the tower top condenser of the methane cryogenic separation tower to provide cold energy for complete gasification at the top of the tower.
  • the nitrogen gas exiting the top condenser is mixed with the gas-liquid separation tank in gas phase, and then enters the cryogenic heat exchanger to recover the cold energy and then carries out the compression cycle.
  • the mixed refrigerant is compressed and cooled in two stages, and then enters the cryogenic heat exchanger for cooling, and the mixed refrigerant exiting the cryogenic heat exchanger enters the methane cryogenic separation tower reboiler to provide heat for the tower kettle , the temperature decreases, the mixed refrigerant exiting the tower kettle reboiler enters the cryogenic heat exchanger for further cooling, the mixed refrigerant exiting the heat exchanger is depressurized through the throttle valve, the temperature is reduced, and then returned to the cryogenic exchange
  • the heater provides refrigeration for nitrogen, raw syngas and itself.
  • coal-to-methanol crude synthesis gas cryogenic separation to natural gas process mainly has two deficiencies:
  • the present invention proposes a process for producing LNG by cryogenic separation of coal-based methane-rich synthesis gas with low energy consumption and reasonable energy and heat utilization. with the system.
  • the invention can achieve the purpose of reducing the amount of mixed refrigerant in the cryogenic separation of methane, reducing the compression work in the process and rationally utilizing the heat generated by the compression.
  • the present invention achieves the above objects through the following technical solutions.
  • a low-energy-consumption coal-based methane-rich synthesis gas cryogenic separation system for producing LNG comprising a nitrogen compression refrigeration unit, a crude synthesis gas cryogenic separation unit, a mixed refrigerant compression refrigeration unit and an ammonia absorption refrigeration unit;
  • the crude synthesis gas cryogenic separation unit includes a first compressor, a first water cooler, a cryogenic heat exchanger, a methane cryogenic separation tower, a crude synthesis gas gas-liquid separation tank, a first expander, and a first throttle valve , LNG cryocooler, second compressor;
  • the first compressor is connected to the first water cooler, the first water cooler is connected to the seventh inlet of the cryogenic heat exchanger, and the seventh outlet of the cryogenic heat exchanger is connected to the methane
  • the tower kettle reboiler of the cryogenic separation tower is connected, the tower kettle reboiler of the methane cryogenic separation tower is connected to the eighth inlet of the cryogenic heat exchanger, and the eighth outlet of the cryogenic heat exchanger is connected to the crude
  • the synthesis gas gas-liquid separation tank is connected, and the top and bottom of the crude synthesis gas-liquid separation tank are respectively connected with the first expander and the first throttle valve, and the first expander and the first throttle valve are connected with the first expander and the first throttle valve respectively.
  • the methane cryogenic separation tower is connected, the methane cryogenic separation tower is connected with the LNG cryogenic device, the LNG cryogenic device is connected with the second compressor, and the second compressor is connected with the deep cryogenic device.
  • the third inlet connection of the cold heat exchanger
  • the nitrogen compression refrigeration unit includes a third compressor, an ammonia water separation tower, a second water cooler, a fourth compressor, a third water cooler, a nitrogen precooler, the cryogenic heat exchanger, and a nitrogen primary gas-liquid separation tank , the second expander, the second throttle valve and the nitrogen secondary gas-liquid separation tank;
  • the third compressor is connected with the tower kettle reboiler of the ammonia water separation tower, the tower kettle reboiler of the ammonia water separation tower is connected with the second water cooler, the second water cooler, the fourth compressor
  • the compressor, the third water cooler and the nitrogen precooler are connected in sequence, the nitrogen precooler is connected to the sixth inlet of the cryogenic heat exchanger, and the sixth outlet of the cryogenic heat exchanger is connected to the nitrogen primary
  • the gas-liquid separation tank is connected, and the top and bottom of the nitrogen primary gas-liquid separation tank are respectively connected with the second expander and the second throttle valve, and the second expander and the second throttle valve are connected with the nitrogen gas.
  • the secondary gas-liquid separation tank is connected, the top of the nitrogen secondary gas-liquid separation tank is connected with the second inlet of the cryogenic heat exchanger, and the second outlet of the cryogenic heat exchanger is connected with the nitrogen precooling
  • the nitrogen precooler is connected with the third compressor; the bottom of the nitrogen secondary gas-liquid separation tank is connected with the top condenser of the methane cryogenic separation tower; the The tower top condenser is connected with the second inlet of the cryogenic heat exchanger;
  • the mixed refrigerant compression refrigeration unit includes a fifth compressor, the ammonia water separation tower, a fourth water cooler, a sixth compressor, a fifth water cooler, the cryogenic heat exchanger, and a mixed refrigerant gas-liquid separation tank , the third throttle valve and the fourth throttle valve;
  • the fifth compressor is connected with the tower kettle reboiler of the ammonia water separation tower, and the tower kettle reboiler, the fourth water cooler, the sixth compressor and the fifth water cooler of the ammonia water separation tower are connected in sequence, so
  • the fifth water cooler is connected to the eleventh inlet of the cryogenic heat exchanger, and the eleventh outlet of the cryogenic heat exchanger is connected to the mixed refrigerant gas-liquid separation tank, and the mixed refrigerant gas
  • the top and bottom of the liquid separation tank are respectively connected with the ninth and tenth inlets of the cryogenic heat exchanger, and the ninth and tenth outlets of the cryogenic heat exchanger are respectively connected with the third throttle valve and the fourth throttle valve.
  • the third throttle valve is connected with the fifth inlet of the cryogenic heat exchanger, the fifth outlet of the cryogenic heat exchanger is connected with the fourth inlet of the cryogenic heat exchanger, the cryogenic heat exchanger
  • the fourth outlet of the heat exchanger is connected with the fifth compressor;
  • the fourth throttle valve is connected with the fourth inlet of the cryogenic heat exchanger;
  • the ammonia absorption refrigeration unit includes a pump, an ammonia water heater, the ammonia water separation tower, a fifth throttle valve, the cryogenic heat exchanger, a sixth throttle valve and a sixth water cooler;
  • the pump, the ammonia water heater and the ammonia water separation tower are connected in sequence, the top of the ammonia water separation tower is connected with the fifth throttle valve, and the fifth throttle valve is connected with the first inlet of the cryogenic heat exchanger , the first outlet of the cryogenic heat exchanger is connected with the sixth water cooler, and the sixth water cooler is connected with the pump; the tower kettle reboiler of the ammonia water separation tower is connected with the ammonia water heater, The ammonia water heater is connected with a sixth throttle valve, and the sixth throttle valve is connected with the sixth water cooler.
  • the nitrogen is compressed by the third compressor and then enters the tower kettle reboiler of the ammonia-water separation tower to provide heat for the tower kettle, and the nitrogen after providing the heat is cooled by the second water cooler and then compressed by the fourth
  • the machine and the third water cooler enter the nitrogen precooler, enter the sixth inlet of the cryogenic heat exchanger after precooling, and enter the nitrogen primary gas-liquid separation tank through the sixth outlet after cryogenic cooling for gas-liquid separation.
  • the phases are expanded and throttled by the second expander and the second throttle valve respectively and enter the nitrogen secondary gas-liquid separation tank for gas-liquid separation.
  • the liquid phase of the nitrogen secondary gas-liquid separation tank enters the tower top of the methane cryogenic separation tower for condensation.
  • the condenser at the top of the tower is mixed with the gas phase of the nitrogen secondary gas-liquid separation tank, and after mixing, it enters the second inlet of the cryogenic heat exchanger, and after providing a part of the cooling capacity, it enters the nitrogen preheater through the second outlet.
  • the crude synthesis gas enters the seventh inlet of the cryogenic heat exchanger through the first compressor and the first water cooler, and enters the methane cryogenic separation tower through the seventh outlet after heat exchange.
  • the tower kettle reboiler provides heat
  • the tower kettle reboiler of the methane cryogenic separation tower enters the eighth inlet of the cryogenic heat exchanger, and enters the crude synthesis gas gas-liquid separation tank through the eighth outlet after cryogenic cooling for gas-liquid separation.
  • the gas phase and the liquid phase are expanded and throttled by the first expander and the first throttle valve respectively, and then enter the methane cryogenic separation tower.
  • the gas phase at the top of the methane cryogenic separation tower enters the LNG cryocooler, enters the third inlet of the cryogenic heat exchanger through the second compressor after heat exchange, and enters the next section through the third outlet after heat exchange;
  • the mixed refrigerant is compressed by the fifth compressor and then enters the reboiler of the ammonia water separation tower to provide heat, and is cooled by the fourth water cooler before entering the sixth compressor for compression. Then, it enters the eleventh inlet of the cryogenic heat exchanger after being cooled by the fifth water cooler. After heat exchange, it enters the mixed refrigerant gas-liquid separation tank through the eleventh outlet for gas-liquid separation, and the gas phase and liquid phase enter the cryogenic exchange respectively.
  • the ninth and tenth inlets of the heat exchanger after heat exchange, the liquid phase comes out from the tenth outlet of the cryogenic heat exchanger and enters the fourth throttle valve, and the gas phase comes out from the ninth outlet of the cryogenic heat exchanger, and passes through the No.
  • the three throttle valves enter the fifth inlet of the cryogenic heat exchanger, and the mixed refrigerant from the fifth outlet of the cryogenic heat exchanger after providing cooling capacity is mixed with the mixed refrigerant passing through the fourth throttle valve, and then together Enter the fourth inlet of the cryogenic heat exchanger, and after heat exchange, enter the fifth compressor through the fourth outlet of the cryogenic heat exchanger for circulation;
  • the ammonia water enters the ammonia water heater through a pump, and then enters the ammonia water separation tower for gas-liquid separation after heating, and the gas phase at the top of the tower enters the first inlet of the cryogenic heat exchanger through the fifth throttle valve, After supplying the cooling capacity, it flows out through the first outlet of the cryogenic heat exchanger, and the liquid phase of the tower still enters the ammonia water heater. After the six water coolers are cooled, they enter the pump for circulation.
  • the flow rate of the mixed refrigerant before entering the compressor is 3760-5170 kmol/h, the temperature is 10-20°C, and the pressure is 1-1.5 bar;
  • the pressure is 16bar-24bar, and the molar percentage of the main components of the mixed refrigerant is: 22%-33% of methane, 2%-4% of nitrogen, 19%-29% of propane, and 36%-54% of ethylene.
  • the temperature of the mixed refrigerant out of the eleventh outlet of the cryogenic heat exchanger is -21°C to -31°C, and the pressure is 16bar-24bar;
  • the temperature of the mixed refrigerant exiting the ninth outlet of the cryogenic heat exchanger is -143°C to -175°C, the pressure is 16bar-24bar, and the pressure of the mixed refrigerant exiting the ninth outlet of the cryogenic heat exchanger after throttling 1-1.5bar;
  • the temperature of the mixed refrigerant exiting the tenth outlet of the cryogenic heat exchanger is -96°C to -118°C, and the pressure is 16bar-24bar. 1-1.5bar.
  • the flow rate of the ammonia water before entering the pump is 5360-7370 kmol/h
  • the molar percentage of the main components of the ammonia water is: ammonia is 20%-30%, water is 70%-80% ;
  • the pressure of the ammonia water entering the ammonia water separation tower is 10-15bar, and the temperature is 109°C-130°C; the ammonia water is passed through the ammonia water separation tower. , water is 0.01%; the outlet temperature of the tower kettle is 123-143 °C, the molar percentage of the main components is: ammonia is 20%, water is 80%, and the pressure after throttling is 1-1.2bar.
  • the inlet flow rate of the crude synthesis gas is 3658-5030kmol/h
  • the temperature is 24-36°C
  • the pressure is 26-40bar
  • the main components of the crude synthesis gas are The mole percentage is: carbon monoxide is 22%-33%, hydrogen is 55%-64%, methane is 8%-15%; the pressure is 38bar-56bar after being compressed.
  • the outlet temperature of the crude synthesis gas at the seventh outlet of the cryogenic heat exchanger is -64.8°C to -97.2°C;
  • the outlet temperature of the crude synthesis gas at the eighth outlet of the cryogenic heat exchanger is -148 to -152°C;
  • the pressure of the crude synthesis gas entering the methane cryogenic separation tower is 9.6bar-14.4bar.
  • the main components of the outlet gas at the top of the tower are as follows: carbon monoxide is 24%-36%, hydrogen is 56%-84%; The molar percentage of the main component of the gas is 90%-95% of methane.
  • the LNG outlet temperature in the LNG cryogenic heat exchanger is -162°C; the synthesis gas at the top of the methane cryogenic separation tower is compressed to 20.8 °C after passing through the LNG cryogenic heat exchanger. -31.2bar.
  • the nitrogen inlet flow rate is 1600-2200kmol/h
  • the temperature is 15-35°C
  • the pressure is 2.8bar-4.2bar
  • the pressure after secondary compression is 22-32bar;
  • the outlet temperature of nitrogen gas through the nitrogen precooler is -67°C to -101°C;
  • the temperature of the nitrogen gas at the sixth outlet of the cryogenic heat exchanger is -155.8°C to -148.2°C, and the gas phase fraction is 0.56-0.84;
  • the expansion pressure of the gas and liquid outlet of the nitrogen primary gas-liquid separation tank is 2.8-4.2 bar;
  • the temperature of the nitrogen gas at the second outlet of the cryogenic heat exchanger is -86.4°C to -129.6°C.
  • the present invention optimizes the process of producing natural gas by cryogenic separation of crude synthesis gas, the newly added ammonia absorption refrigeration unit does not need to be compressed, the energy consumption is low, and the heat of the ammonia water separation tower tower kettle utilizes the compression heat of the original process, and can Providing a certain cooling capacity reduces the outlet temperature and flow of the mixed refrigerant and reduces the compression work. Achieving higher resource utilization and reducing the cost of factory adjustment of the process with small equipment changes can be widely used in the optimization of traditional processes.
  • the present invention optimizes the traditional coal-based methane-rich synthesis gas cryogenic separation process for natural gas production, the energy consumption is reduced by 25.8%, the compression power heat utilization rate is increased by 33.40%, the mixed refrigerant flow rate is reduced by 15.31%, and the mixed refrigerant The energy used to cool itself has been reduced to 83.5%.
  • Figure 1 is a process flow diagram of a traditional coal-based methane-rich synthesis gas cryogenic separation to produce natural gas.
  • Fig. 2 is a process flow diagram of the present invention for producing natural gas by cryogenic separation of coal-based methane-rich synthesis gas.
  • FIG. 3 is a schematic structural diagram of the cryogenic heat exchanger of the present invention.
  • a low-energy-consumption coal-based methane-rich synthesis gas cryogenic separation system for producing LNG comprising a nitrogen compression refrigeration unit, a crude synthesis gas cryogenic separation unit, a mixed refrigerant compression refrigeration unit and an ammonia absorption refrigeration unit;
  • the crude synthesis gas cryogenic separation unit includes a first compressor 1, a first water cooler 2, a cryogenic heat exchanger 3, a methane cryogenic separation tower 4, a crude synthesis gas gas-liquid separation tank 5, and a first expander 6 , the first throttle valve 7, the LNG cryocooler 8, the second compressor 9;
  • the first compressor 1 is connected to the first water cooler 2, the first water cooler 2 is connected to the seventh inlet of the cryogenic heat exchanger 3, and the seventh inlet of the cryogenic heat exchanger 3 is connected.
  • the outlet is connected with the tower kettle reboiler of the methane cryogenic separation tower 4, and the tower kettle reboiler of the methane cryogenic separation tower 4 is connected with the eighth inlet of the cryogenic heat exchanger 3.
  • the eighth outlet of the heat exchanger 3 is connected to the crude synthesis gas gas-liquid separation tank 5, and the top and bottom of the crude synthesis gas gas-liquid separation tank 5 are respectively connected to the first expander 6 and the first throttle valve 7,
  • the first expander 6 and the first throttle valve 7 are connected to the methane cryogenic separation tower 4, and the methane cryogenic separation tower 4 is connected to the LNG cryogenic device 8, and the LNG cryogenic device 8 connected with the second compressor 9, which is connected with the third inlet of the cryogenic heat exchanger 3;
  • the nitrogen compression refrigeration unit includes a third compressor 10, an ammonia water separation tower 11, a second water cooler 12, a fourth compressor 13, a third water cooler 14, a nitrogen precooler 15, and the cryogenic heat exchanger 3 , Nitrogen primary gas-liquid separation tank 16, second expander 17, second throttle valve 18 and nitrogen secondary gas-liquid separation tank 19;
  • the third compressor 10 is connected with the tower kettle reboiler of the ammonia water separation tower 11, and the tower kettle reboiler of the ammonia water separation tower 11 is connected with the second water cooler 12, and the second water cooler 12.
  • the fourth compressor 13, the third water cooler 14, and the nitrogen precooler 15 are connected in sequence, and the nitrogen precooler 15 is connected to the sixth inlet of the cryogenic heat exchanger 3, and the cryogenic heat exchange
  • the sixth outlet of the device 3 is connected to the primary nitrogen gas-liquid separation tank 16, and the top and bottom of the primary nitrogen gas-liquid separation tank 16 are respectively connected to the second expander 17 and the second throttle valve 18, so
  • the second expander 17 and the second throttle valve 18 are connected to the nitrogen secondary gas-liquid separation tank 19, and the top of the nitrogen secondary gas-liquid separation tank 19 is connected to the second side of the cryogenic heat exchanger 3.
  • the inlet is connected, the second outlet of the cryogenic heat exchanger 3 is connected with the nitrogen precooler 15, and the nitrogen precooler 15 is connected with the third compressor 10; the nitrogen secondary gas-liquid separation tank 19
  • the bottom of the tower is connected with the overhead condenser of the methane cryogenic separation tower 4; the overhead condenser of the methane cryogenic separation tower 4 is connected with the second inlet of the cryogenic heat exchanger 3;
  • the mixed refrigerant compression refrigeration unit includes the fifth compressor 20, the ammonia water separation tower 11, the fourth water cooler 21, the sixth compressor 22, the fifth water cooler 23, the cryogenic heat exchanger 3, the mixing Refrigerant gas-liquid separation tank 24, third throttle valve 25 and fourth throttle valve 26;
  • the fifth compressor 20 is connected with the tower kettle reboiler of the ammonia water separation tower 11, the tower kettle reboiler, the fourth water cooler 21, the sixth compressor 22, the fifth water cooling device of the ammonia water separation tower 11
  • the fifth water cooler 23 is connected to the eleventh inlet of the cryogenic heat exchanger 3, and the eleventh outlet of the cryogenic heat exchanger 3 is separated from the mixed refrigerant gas and liquid
  • the tank 24 is connected, and the top and bottom of the mixed refrigerant gas-liquid separation tank 24 are respectively connected to the ninth and tenth inlets of the cryogenic heat exchanger 3, and the ninth and tenth outlets of the cryogenic heat exchanger 3 They are respectively connected with the third throttle valve 25 and the fourth throttle valve 26.
  • the third throttle valve 25 is connected with the fifth inlet of the cryogenic heat exchanger 3.
  • the fifth outlet is connected to the fourth inlet of the cryogenic heat exchanger 3, and the fourth outlet of the cryogenic heat exchanger 3 is connected to the fifth compressor 20;
  • the fourth throttle valve 26 is connected to the cryogenic heat exchanger The fourth inlet connection of device 3;
  • the ammonia absorption refrigeration unit includes a pump 27, an ammonia water heater 28, the ammonia water separation tower 11, the fifth throttle valve 29, the cryogenic heat exchanger 3, the sixth throttle valve 30 and the sixth water cooler 31 ;
  • the pump 27, the ammonia water heater 28, and the ammonia water separation tower 11 are connected in sequence, and the top of the ammonia water separation tower 11 is connected to the fifth throttle valve 29, and the fifth throttle valve 29 exchanges heat with the cryogenic temperature.
  • the first inlet of the cryogenic heat exchanger 3 is connected to the first inlet of the cryogenic heat exchanger 3, and the first outlet of the cryogenic heat exchanger 3 is connected to the sixth water cooler 31.
  • the sixth water cooler 31 is connected to the pump 27; the ammonia water separation tower 11
  • the tower kettle reboiler is connected with the ammonia water heater 28, the ammonia water heater 28 is connected with the sixth throttle valve 30, and the sixth throttle valve 30 is connected with the sixth water cooler 31.
  • the initial nitrogen temperature is 15°C
  • the pressure is 2.8bar
  • the flow rate is 1600kmol/h. It is compressed to 15.5bar by the compressor, and the compressed stream enters the reboiler of the ammonia water separation tower tower kettle to provide heat for the tower kettle.
  • the nitrogen is cooled to 33°C by the water cooler and then compressed to 22bar by the compressor, cooled to 33°C by the water cooler, and then entered into the nitrogen precooler for precooling.
  • the outlet temperature is -67°C, and then enters the cryogenic heat exchange.
  • the device is further cooled to -155.8 °C, the gas phase fraction is 0.56, and enters the nitrogen primary gas-liquid separation tank for gas-liquid separation.
  • the nitrogen in the liquid phase provides cold energy gasification for the top of the methane separation tower
  • the outlet temperature is -86.4 ° C, and then Enter the nitrogen pre-cooler to pre-cool nitrogen, and the outlet temperature is 15 ° C and then circulate.
  • the initial crude synthesis gas temperature was 24°C, pressure was 26 bar, flow rate was 3658 kmol/h, and the composition was 27% CO, 62% H 2 , 10.05% CH 4 , 0.71% C 2 H 6 and 0.24% N in molar percentage. 2 with AR. It is compressed to 38bar by the compressor, then cooled to 35°C by the water cooler, and then enters the cryogenic heat exchanger to cool down to -64.8°C.
  • the crude synthesis gas at -64.8°C enters the methane cryogenic separation tower tower kettle reboiler to provide heat, and the The crude syngas in the tower kettle reboiler enters the cryogenic heat exchanger to cool down to -148°C, and the crude syngas at -148°C enters the crude syngas gas-liquid separation tank for gas-liquid separation, and the gas phase and liquid phase are respectively expanded and separated. Throttle to 9.6bar and enter the methane cryogenic separation tower. After separation, the temperature at the top of the tower is -181°C, the flow rate is 3251kmol/h, and the molar percentage of its main components is carbon monoxide at 30.6% and hydrogen at 69.29%. The outlet temperature of the tower kettle is -124°C, the flow rate is 407kmol/h, and the molar percentage of its main component is methane at 93%.
  • the LNG is cooled to -162°C and then enters the next section.
  • the temperature of the synthesis gas exiting the LNG cryocooler is -170.1 After being compressed to 20.8 bar, it enters the cryogenic heat exchanger for cold energy recovery and the outlet temperature is 30 °C and then enters the next section.
  • the initial mixed refrigerant temperature was 10 °C
  • the pressure was 1 bar
  • the flow rate was 3760 kmol/h.
  • the composition is 28% CH 4 , 3% N 2 , 24% propane and 45% ethylene in molar percentage.
  • the water cooler is cooled to 33°C, and then enters the compressor to be compressed to 16bar, cooled to 33°C by the water cooler, cooled to -21°C by the cryogenic heat exchanger, and entered into the mixed refrigerant gas-liquid separation tank for gas-liquid separation.
  • the liquid phase enters the cryogenic heat exchanger and is cooled to -96°C, the liquid phase at the bottom of the tank cooled to -96°C is throttled to a gas-liquid mixture of 1 bar, and the gas phase at the top of the tank cooled to -96°C enters the cryogenic
  • the heat exchanger is cooled to -143°C, throttled to 1bar, and circulated back to the cryogenic heat exchanger to provide cooling capacity for nitrogen, raw gas and itself.
  • the gas-liquid mixture with a phase throttling of 1.235 bar is mixed and then enters the cryogenic heat exchanger to provide nitrogen, raw gas and itself with cold energy to heat up to 10 ° C for circulation.
  • the initial dilute ammonia temperature is 24°C
  • the pressure is 1bar
  • the flow rate is 5360kmol/h
  • the composition is 25% NH 3 and 75% H 2 O in molar percentage.
  • the pump is pressurized to 10bar and then heated to 109°C by the ammonia heater.
  • the dilute ammonia water in the tower kettle (ammonia mole fraction 20%, temperature is 123°C) enters the ammonia water heater to heat the raw material and the outlet temperature is 29°C, and then enters the throttle valve to throttle to 1 bar.
  • Concentrated ammonia water at the top of the tower (ammonia mole fraction 99.99%, temperature 25°C) is throttled to 1bar and temperature is -29°C, and then enters the cryogenic heat exchanger to pre-cool the mixed refrigerant and raw gas, reducing the output of the mixed refrigerant.
  • the temperature of the cryogenic heat exchanger reduces the compression work. After leaving the cryogenic heat exchanger, it is mixed with 1 bar of dilute ammonia water after heat recovery and enters the water cooler to cool to 24°C for circulation.
  • the energy consumption of the traditional technological process is 21790.89, the energy consumption of the technological process of this embodiment is 16165.75, and the energy saving is 25.8%.
  • the heat generated by the compression of the traditional process flow and needs to be cooled by cooling water is 23466.68kW, the heat generated by the compression of the process flow in this embodiment and needs to be cooled by cooling water is 15956kW, and the heat generated by the process flow in this embodiment is 5328.92 kW kW, accounting for 33.39% of the total, and the compression power and heat utilization rate increased by 33.39%.
  • the cooling capacity required for the cooling of the mixed refrigerant in the traditional process is 23743.5kW, the cooling capacity is 26742.25kW, and the cooling itself accounts for 88.786%.
  • the flow rate of the mixed refrigerant in the traditional process flow is 4440kmol/h, and the flow rate of the mixed refrigerant in the process flow of this embodiment is 3760kmol/h, a reduction of 15.31%.
  • the initial nitrogen temperature was 24°C
  • the pressure was 3.5bar
  • the flow rate was 1900kmol/h.
  • the compressed stream After being compressed to 15.5bar by the compressor, the compressed stream enters the reboiler of the tower kettle of the ammonia water separation tower to provide heat for the tower kettle.
  • the nitrogen gas After supplying heat, the nitrogen gas is cooled to 33°C by the water cooler and then compressed to 27bar by the compressor, cooled to 33°C by the water cooler, and then enters the nitrogen precooler for precooling.
  • the outlet temperature is -85°C, and then enters the cryogenic heat exchange.
  • the device is further cooled to -151.5 °C, the gas phase fraction is 0.7, enters the nitrogen primary gas-liquid separation tank for gas-liquid separation, the gas and liquid are expanded and throttled to 3.5 bar, and enter the nitrogen secondary gas-liquid separation tank again for gas-liquid separation Separation, in which the nitrogen in the liquid phase provides cold gasification for the top of the methane separation tower, and the temperature of mixing with the gas phase of the nitrogen secondary gas-liquid separation tank is -184 ° C, and the temperature at the outlet of the cryogenic heat exchanger for cold recovery is -100 °C, then enter the nitrogen precooler to pre-cool the nitrogen outlet temperature to 24 °C and then circulate.
  • the initial crude syngas temperature was 30°C
  • pressure was 33 bar
  • flow rate was 4333 kmol/h
  • the composition was 27% CO, 62% H 2 , 10.05% CH 4 , 0.71% C 2 H 6 and 0.24% N in molar percentage 2 with AR. It is compressed to 47bar by the compressor, then cooled to 35°C by the water cooler, and then enters the cryogenic heat exchanger to cool down to -81°C.
  • the raw material gas at -81°C enters the methane cryogenic separation tower tower kettle reboiler to provide heat, and exits the tower
  • the crude syngas in the kettle reboiler enters the cryogenic heat exchanger to cool down to -150°C, and the crude syngas at -150°C enters the crude syngas gas-liquid separation tank for gas-liquid separation. It flows to 12bar and enters the methane cryogenic separation tower.
  • the LNG (-120°C) in the tower reactor and the synthesis gas (-180°C) at the top of the tower enter the LNG cryocooler, and the LNG is cooled to -162°C and then enters the next section.
  • the temperature of the syngas in the LNG cryocooler is -170°C, after being compressed to 26.3bar, it enters the cryogenic heat exchanger for cold energy recovery and then enters the next section.
  • the outlet temperature of the top of the tower is -180°C
  • the flow rate is 3858kmol/h
  • the molar percentage of its main components is carbon monoxide at 30.54% and hydrogen at 69.10%.
  • the outlet temperature of the tower kettle is -120°C
  • the flow rate is 475kmol/h
  • the molar percentage of its main component is methane at 93%.
  • the initial mixed refrigerant temperature is 16.1°C
  • the pressure is 1.2bar
  • the flow rate is 4465kmol/h
  • the composition is 28% CH 4 , 3% N 2 , 24% propane and 45% ethylene in molar percentage, compressed to 15 bar, into the
  • the ammonia water separation tower tower kettle reboiler provides heat, and the mixed refrigerant from the tower kettle is cooled to 33 °C by the water cooler, and then enters the compressor to be compressed to 20.21 bar, cooled to 33 °C by the water cooler, and then enters the cryogenic heat exchanger Cool to -26°C, enter the mixed refrigerant gas-liquid separation tank for gas-liquid separation, the gas phase and liquid phase enter the cryogenic heat exchanger respectively to cool to -107°C, and the liquid phase at the bottom of the tank cooled to -107°C is throttled as The gas-liquid mixture of 1.235bar is cooled to -107°C in the tank top gas phase and then enters the cryogenic
  • cryogenic heat exchanger After leaving the cryogenic heat exchanger, it is mixed with the gas-liquid mixture with a liquid phase throttle of 1.2 bar at the top of the tank that is cooled to -107 °C, and then enters the cryogenic heat exchanger as Nitrogen gas, raw material gas and self-provided cooling capacity are heated to 16.1 °C for circulation.
  • the initial dilute ammonia temperature is 30°C
  • the pressure is 1.2bar
  • the flow rate is 6365kmol/h
  • the composition is 25% NH 3 and 75% H 2 O in molar percentage.
  • °C into the ammonia water separation tower for ammonia water separation.
  • the dilute ammonia water in the tower kettle (ammonia mole fraction 20%, temperature is 135.9°C) enters the ammonia water heater to heat the raw material and the outlet temperature is 36.35°C, and then enters the throttle valve and the throttle is 1.2bar.
  • the concentrated ammonia water at the top of the tower (ammonia mole fraction 99.99%, temperature is 34°C) is throttled to 1.2bar, temperature is -29.55°C, and then enters the cryogenic heat exchanger to pre-cool the mixed refrigerant and raw gas to reduce the mixed refrigerant
  • the temperature of the cryogenic heat exchanger reduces the compression work, and after leaving the cryogenic heat exchanger, it is mixed with 1.2 bar of dilute ammonia water after heat recovery and enters the water cooler to cool to 30 °C for circulation.
  • the energy consumption of the traditional technological process is 25794.97kW, and the energy consumption of the technological process of this embodiment is 19136.21kW, and the energy saving is 25.8%.
  • the heat generated by the compression of the traditional process and needs to be cooled by the cooling water is 27778.68kW.
  • the heat generated by the compression of the process in this embodiment and needs to be cooled by the cooling water is 18889.8kW.
  • the heat generated by the process of the embodiment is 6308.11kW, accounting for 33.39% of the total.
  • the cooling capacity required for the cooling of the mixed refrigerant in the traditional process is 28106.37kW, the cooling capacity is 31656.14kW, and the cooling itself accounts for 88.786%. Its own accounted for 83.5%.
  • the flow rate of the mixed refrigerant in the traditional process flow is 5272kmol/h, and the flow rate of the mixed refrigerant in the process flow of this embodiment is 4465kmol/h, a decrease of 15.31%.
  • the initial nitrogen temperature was 35°C
  • the pressure was 4.2 bar
  • the flow rate was 2200 kmol/h.
  • the compressed stream enters the tower kettle reboiler of the ammonia water separation tower to provide heat for the tower kettle.
  • the nitrogen gas is cooled to 33°C by the water cooler and then compressed to 32bar by the compressor, cooled to 33°C by the water cooler, and then enters the nitrogen precooler for precooling, the outlet temperature is -101°C, and then enters the cryogenic heat exchange.
  • the gas-liquid separator was further cooled to -148.2°C, the gas phase fraction was 0.84, and entered the primary nitrogen gas-liquid separation tank for gas-liquid separation.
  • the nitrogen in the liquid phase provides cold gasification for the top of the methane separation tower
  • the temperature of mixing with the gas phase of the nitrogen secondary gas-liquid separation tank is -184 ° C
  • the temperature at the outlet of the cryogenic heat exchanger for cold recovery is -129.6 °C
  • the initial crude syngas temperature was 36°C
  • pressure was 40 bar
  • flow rate was 5030 kmol/h
  • the composition was 27% CO, 62% H 2 , 10.05% CH 4 , 0.71% C 2 H 6 and 0.24% N in molar percentage 2 with AR. It is compressed to 56bar by the compressor, then cooled to 35°C by the water cooler, and then enters the cryogenic heat exchanger to cool down to -97.2°C.
  • the raw material gas at -97.2°C enters the methane cryogenic separation tower tower kettle reboiler to provide heat, and exits the tower.
  • the crude syngas in the kettle reboiler enters the cryogenic heat exchanger to cool down to -152°C, and the crude syngas at -152°C enters the crude syngas gas-liquid separation tank for gas-liquid separation, and the gas phase and liquid phase are expanded and compressed respectively. It flows to 14.4bar and enters the methane cryogenic separation tower.
  • the LNG (-114°C) in the tower reactor and the synthesis gas (-177°C) at the top of the tower enter the LNG cryocooler, and the LNG is cooled to -162°C and then enters the next section.
  • the temperature of the syngas exiting the LNG cryocooler is -170°C, after being compressed to 31.2bar, it enters the cryogenic heat exchanger for cold energy recovery and then enters the next section.
  • the column top outlet temperature is -177°C
  • the flow rate is 4478kmol/h
  • the molar percentages of its main components are carbon monoxide at 29.4% and hydrogen at 70.20%.
  • the outlet temperature of the tower kettle is -114°C
  • the flow rate is 552kmol/h
  • the molar percentage of its main component is methane at 93%.
  • the initial mixed refrigerant temperature is 20°C
  • the pressure is 1.5bar
  • the flow rate is 5170kmol/h
  • the composition is 28% CH 4 , 3% N 2 , 24% propane and 45% ethylene in molar percentage, compressed to 15 bar, and entering
  • the ammonia water separation tower tower kettle reboiler provides heat, and the mixed refrigerant out of the tower kettle is cooled to 33 °C by the water cooler, and then enters the compressor to be compressed to 24 bar, cooled to 33 °C by the water cooler, and then enters the cryogenic heat exchanger for cooling When the temperature reaches -31 °C, it enters the mixed refrigerant gas-liquid separation tank for gas-liquid separation.
  • the gas phase and liquid phase enter the cryogenic heat exchanger respectively to be cooled to -118 °C, and the liquid phase at the bottom of the tank cooled to -118 °C is throttled to 1.5
  • the gas-liquid mixture at bar is cooled to -118°C in the tank top gas phase and then enters the cryogenic heat exchanger to be cooled to -163°C, throttled to 1.5bar, the temperature is reduced to -165°C, and circulated back to the cryogenic heat exchanger Provide cooling capacity for nitrogen, raw gas and itself. After leaving the cryogenic heat exchanger, it is mixed with the gas-liquid mixture with a liquid phase throttle of 1.5 bar at the top of the tank that is cooled to -118°C, and then enters the cryogenic heat exchanger for nitrogen. , The raw gas and the cooling capacity provided by itself are heated to 20 °C for circulation.
  • the initial dilute ammonia temperature is 30°C
  • the pressure is 1.2bar
  • the flow rate is 7370kmol/h
  • the composition is 25% NH 3 , 75% H 2 O in molar percentage, pressurized to 15 bar by the pump, and then heated to 130 by the ammonia water heater °C into the ammonia water separation tower for ammonia water separation.
  • the dilute ammonia water in the tower kettle (ammonia mole fraction 20%, temperature is 143°C) enters the ammonia water heater to heat the raw material and the outlet temperature is 36°C, and then enters the throttle valve and the throttle is 1.2bar.
  • the concentrated ammonia water at the top of the tower (ammonia mole fraction 99.99%, temperature 39°C) is throttled to 1.2bar, temperature is -29.55°C, and then enters the cryogenic heat exchanger to pre-cool the mixed refrigerant and raw gas to reduce the mixed refrigerant
  • the temperature of the cryogenic heat exchanger reduces the compression work, and after leaving the cryogenic heat exchanger, it is mixed with 1.2 bar of dilute ammonia water after heat recovery and enters the water cooler to cool to 30 °C for circulation.
  • the energy consumption of the traditional technological process is 30960 kW, and the energy consumption of the technological process of this embodiment is 22972 kW, and the energy saving is 25.8%.
  • the heat generated by the compression of the traditional process and required to be cooled by the cooling water is 33340kW.
  • the heat generated by the compression of the process in this embodiment and required to be cooled by the cooling water is 22670kW.
  • the cooling capacity required for mixed refrigerant cooling is 33730kW, the generated cooling capacity is 37990kW, and the cooling itself accounts for 88.786%. %.
  • the flow rate of the mixed refrigerant in the traditional process flow is 6104kmol/h, and the flow rate of the mixed refrigerant in the process flow of this embodiment is 5170kmol/h, a reduction of 15.31%.

Abstract

本发明公开了一种煤基富甲烷合成气深冷分离制LNG的工艺与系统，属于煤化工领域。该系统包括氮气压缩制冷单元、粗合成气深冷分离单元、混合制冷剂压缩制冷单元和氨吸收制冷单元。本发明新添加的氨吸收制冷单元无需压缩，能耗低，且氨水分离塔塔釜热量将原流程的压缩热利用了起来，且能提供一定的冷量降低混合制冷剂的出口温度与流量，减少了压缩功。相对于传统煤制甲醇粗合成气深冷分离制天然气工艺，本发明能耗降低了25.8％，压缩功热利用率提高了33.40％，混合制冷剂流量下降了15.31％，混合制冷剂用于冷却自身的能量降低至83.5％，解决了传统工艺存在能耗高、热利用不充分、混合制冷剂能量利用不合理的问题。

Description

一种煤基富甲烷合成气深冷分离制LNG的工艺与系统 技术领域
本发明属于煤化工领域，具体涉及一种煤基富甲烷合成气深冷分离制LNG的工艺与系统。
背景技术
国内富煤、少气、缺油的资源现状，探明的煤储量有2000亿吨，国内相当大一部分有机化工产品有煤转化而来，以甲醇为例，80％的甲醇都是由煤炭转化而来的。甲醇在碳一化工领域占据一定的地位，是一种清洁环保燃料可与汽油柴油以一定的比例进行混合用于甲醇汽车燃料，并且可脱水制烯烃。
国内的烯烃大多是基于石脑油的裂解，作为原油进口大国，发展煤制甲醇是调整国家能源结构，降低烯烃工业对原油进口的依赖度具有一定的现实意义。在此背景下，煤制甲醇等化工产品是一项发展迅速、前景广阔的工业。
而粗合成气深冷分离对于煤化工产品质量具有重要意义，在此过程中分离的LNG(天然气)是清洁安全的优质能源，广泛运用于商业、民用、化工与发电产业，随着大气污染治理压力的不断增大，天然气市场供需缺口大，天然气进口量大，分离的LNG同时也能满足天然气市场需求，减少天然气进口。
传统的煤基富甲烷合成气深冷分离制天然气工艺如图1所示，主要流程描述如下：
全流程分为三个部分，分别是氮气压缩制冷、粗合成气深冷分离、混合制冷剂压缩制冷。
粗合成气深冷分离：粗合成气经压缩机与水冷器，进入深冷换热器降温深冷，出深冷换热器的合成气进入粗合成气气液分离罐进行气液分离，气相经膨胀机降压降温，液相经节流阀。出膨胀机和节流阀的粗合成气同时进入甲烷深冷分离塔进行分离，塔顶出口的合成气与塔釜出口的天然气进入LNG深冷器，出口天然气被冷却进入下一工段，出LNG深冷器的合成气经压缩机进入深冷换热器进行换热回收冷量，再进入下一个工段。
氮气压缩制冷：氮气经两段压缩与降温，降温后的氮气经氮气预冷器降温后，进入深冷 换热器进行降温深冷，出深冷换热器的氮气进入氮气一次气液分离罐进行气液分离，气相经膨胀机降压，液相经节流阀降压，温度进一步降低。降压后的气相与液相再进入氮气一次气液分离罐进行气液分离，液相进入甲烷深冷分离塔的塔顶冷凝器为塔顶提供冷量完全气化。出塔顶冷凝器的氮气与气液分离罐气相混合，然后进入深冷换热器回收冷量后再进行压缩循环。
混合制冷剂压缩制冷:混合制冷剂经两段压缩与降温，再进入深冷换热器进行降温，出深冷换热器的混合制冷剂进入甲烷深冷分离塔再沸器为塔釜提供热量，温度降低，出塔釜再沸器的混合制冷剂再进入深冷换热器进行进一步的降温，出换热器的混合制冷剂经过节流阀降压，温度降低，再回流回深冷换热器为氮气、粗合成气与其本身提供冷量。
上述煤制甲醇粗合成气深冷分离制天然气工艺主要存在两点不足：
(1)全流程混合制冷剂、粗合成气、氮气压缩后所产生的热量全部由公用工程的冷却水提供冷量进行降温，造成冷却水的循环量大、成本高，并且热量没有合理利用，不节能环保。
(2)混合制冷剂的88.786％冷量用于冷却自身，剩下的11.22％用于冷却混合制冷剂与粗合成气，能量利用的不合理，导致混合制冷剂的用量增加，压缩的压力偏高，压缩功大，能耗高。
总而言之，传统工艺存在能耗高、热利用不充分、混合制冷剂能量利用不合理的问题。
发明内容
本发明为了克服以上能耗高、热利用不充分、混合制冷剂能量利用不合理的问题，提出了一种低能耗与能量与热利用合理的煤基富甲烷合成气深冷分离制LNG的工艺与系统。通过本发明可以实现降低甲烷深冷分离中混合制冷剂的用量、减少过程中的压缩功并合理利用压缩所产生的热的目的。
本发明通过以下技术方案实现以上目的。
一种低能耗煤基富甲烷合成气深冷分离制LNG系统，包括氮气压缩制冷单元、粗合成气深冷分离单元、混合制冷剂压缩制冷单元和氨吸收制冷单元；
其中主要包括氮气一次气液分离罐，氮气预冷器，氮气二次气液分离罐，深冷换热器，粗合成气气液分离罐，甲烷深冷分离塔，LNG深冷器，混合制冷剂气液分离罐，氨水加热器，氨水分离塔；
所述粗合成气深冷分离单元包括第一压缩机、第一水冷器、深冷换热器、甲烷深冷分离塔、粗合成气气液分离罐、第一膨胀机、第一节流阀、LNG深冷器、第二压缩机；
所述第一压缩机与所述第一水冷器连接，所述第一水冷器与所述深冷换热器的第七进口连接，所述深冷换热器的第七出口与所述甲烷深冷分离塔的塔釜再沸器连接，所述甲烷深冷分离塔的塔釜再沸器与所述深冷换热器第八进口连接，所述深冷换热器第八出口与粗合成气气液分离罐连接，所述粗合成气气液分离罐的顶部、底部分别与所述第一膨胀机、第一节流阀连接，所述第一膨胀机、第一节流阀与所述甲烷深冷分离塔连接，所述甲烷深冷分离塔与所述LNG深冷器连接，所述LNG深冷器与所述第二压缩机连接，所述第二压缩机与所述深冷换热器的第三进口连接；
所述氮气压缩制冷单元包括第三压缩机、氨水分离塔、第二水冷器、第四压缩机、第三水冷器、氮气预冷器、所述深冷换热器、氮气一次气液分离罐、第二膨胀机、第二节流阀和氮气二次气液分离罐；
所述第三压缩机与所述氨水分离塔的塔釜再沸器相连，所述氨水分离塔的塔釜再沸器与所述第二水冷器相连，所述第二水冷器、第四压缩机、第三水冷器、氮气预冷器依次连接，所述氮气预冷器与所述深冷换热器的第六进口相连，所述深冷换热器的第六出口与所述氮气一次气液分离罐连接，所述氮气一次气液分离罐的顶部、底部分别与所述第二膨胀机、第二节流阀连接，所述第二膨胀机、第二节流阀与所述氮气二次气液分离罐连接，所述氮气二次气液分离罐的顶部与所述深冷换热器的第二进口连接，所述深冷换热器的第二出口与所述氮气预冷器连接，所述氮气预冷器与第三压缩机连接；所述氮气二次气液分离罐的底部与所述甲烷深冷分离塔的塔顶冷凝器连接；所述甲烷深冷分离塔的塔顶冷凝器与所述深冷换热器的第二进口连接；
所述混合制冷剂压缩制冷单元包括第五压缩机、所述氨水分离塔、第四水冷器、第六压缩机、第五水冷器、所述深冷换热器、混合制冷剂气液分离罐、第三节流阀和第四节流阀；
所述第五压缩机与所述氨水分离塔的塔釜再沸器连接，所述氨水分离塔的塔釜再沸器、第四水冷器、第六压缩机、第五水冷器依次连接，所述第五水冷器与所述深冷换热器的第十一进口连接，所述深冷换热器的第十一出口与所述混合制冷剂气液分离罐连接，所述混合制冷剂气液分离罐的顶部、底部分别与深冷换热器的第九、第十进口连接，所述深冷换热器的第九、第十出口分别与第三节流阀、第四节流阀连接，所述第三节流阀与所述深冷换热器的第五进口连接，所述深冷换热器的第五出口与深冷换热器的第四进口连接，所述深冷换热器的第四出口与第五压缩机连接；所述第四节流阀与所述深冷换热器的第四进口连接；
所述氨吸收制冷单元包括泵、氨水加热器、所述氨水分离塔、第五节流阀、所述深冷换热器、第六节流阀和第六水冷器；
所述泵、氨水加热器、氨水分离塔依次连接，所述氨水分离塔的塔顶与第五节流阀连接，所述第五节流阀与所述深冷换热器的第一进口连接，所述深冷换热器的第一出口与所述第六水冷器连接，所述第六水冷器与所述泵连接；所述氨水分离塔的塔釜再沸器与氨水加热器连接，所述氨水加热器与第六节流阀连接，所述第六节流阀与所述第六水冷器连接。
利用以上所述的一种低能耗煤基富甲烷合成气深冷分离制LNG的工艺与系统，包括氮气压缩制冷过程、粗合成气深冷分离过程、混合制冷剂压缩制冷过程和氨吸收制冷过程；
在所述氮气压缩制冷过程中，氮气经第三压缩机压缩后进入氨水分离塔的塔釜再沸器为塔釜提供热量，提供热量后的氮气经第二水冷器冷却后再经第四压缩机与第三水冷器进入氮气预冷器，经预冷后进入深冷换热器的第六进口，经深冷后经过第六出口进入氮气一次气液分离罐进行气液分离，气相、液相分别经第二膨胀机、第二节流阀膨胀节流进入氮气二次气液分离罐再进行气液分离，氮气二次气液分离罐的液相进入甲烷深冷分离塔的塔顶冷凝器，经换热后出塔顶冷凝器与氮气二次气液分离罐的气相相混合，经混合后进入深冷换热器的第二进口，提供一部分冷量后经第二出口进入氮气预冷器，出氮气预冷器后进入第三压缩机进 行循环；
在所述粗合成气深冷分离过程中，粗合成气经第一压缩机与第一水冷器进入深冷换热器的第七进口，换热后经过第七出口进入甲烷深冷分离塔的塔釜再沸器提供热量，出甲烷深冷分离塔的塔釜再沸器后进入深冷换热器第八进口，深冷后经过第八出口进入粗合成气气液分离罐中进行气液分离，气相、液相分别经第一膨胀机、第一节流阀膨胀节流后进入甲烷深冷分离塔，甲烷深冷分离塔塔釜的液相进入LNG深冷器，深冷后进入下一工段，甲烷深冷分离塔塔顶的气相进入LNG深冷器，换热后经第二压缩机进入深冷换热器的第三进口，换热后经过第三出口进入下一工段；
在所述混合制冷剂压缩制冷过程中，混合制冷剂经第五压缩机压缩后进入氨水分离塔的塔釜再沸器提供热量，再经第四水冷器冷却后再进入第六压缩机压缩，然后经第五水冷器冷却后进入深冷换热器的第十一进口，换热后经过第十一出口进入混合制冷剂气液分离罐进行气液分离，气相与液相分别进入深冷换热器的第九、第十进口，经换热后，液相由深冷换热器的第十出口出来进入第四节流阀，气相由深冷换热器的第九出口出来，经过第三节流阀进入深冷换热器的第五进口，提供冷量后由深冷换热器的第五出口出来的混合制冷剂与经过第四节流阀的混合制冷剂相混合，再共同进入深冷换热器的第四进口，换热后经深冷换热器的第四出口进入第五压缩机进行循环；
在所述氨吸收制冷过程中，氨水经一台泵进入氨水加热器，加热后进入氨水分离塔进行气液分离，塔顶气相经第五节流阀进入深冷换热器的第一进口，提供冷量后经深冷换热器的第一出口流出，塔釜液相进入氨水加热器，提供热量后流出再经第六节流阀与深冷换热器的第一出口物流混合经第六水冷器冷却后进入泵中进行循环。
优选的，在所述混合制冷剂压缩制冷过程中，混合制冷剂在进压缩机前的流量为3760-5170kmol/h，温度为10-20℃，压力为1-1.5bar；二级压缩后的压力为16bar-24bar，所述混合制冷剂主要组分摩尔百分比为：甲烷22％-33％，氮气在2％-4％，丙烷在19％-29％，乙烯在36％-54％。
优选的，在所述混合制冷剂压缩制冷过程中，所述混合制冷剂出深冷换热器第十一出口的温度为-21℃至-31℃，压力为16bar-24bar；
所述混合制冷剂出深冷换热器第九出口的温度为-143℃至-175℃，压力为16bar-24bar，经深冷换热器第九出口出来的混合制冷剂节流后的压力为1-1.5bar；
所述混合制冷剂出深冷换热器第十出口温度为-96℃至-118℃，压力为16bar-24bar，经深冷换热器第十出口出来的混合制冷剂节流后的压力在1-1.5bar。
优选的，在所述氨吸收制冷过程中，所述氨水在进入泵前流量为5360-7370kmol/h，氨水主要组分摩尔百分比为：氨为20％-30％，水为70％-80％；所述氨水进氨水分离塔的压力为10-15bar，温度为109℃-130℃；氨水经氨水分离塔后塔顶出口温度为25-39℃，主要组分摩尔百分比为：氨为99.99％，水为0.01％；塔釜出口温度为123-143℃，主要组分摩尔百分比为：氨为20％，水为80％,节流后压力在1-1.2bar。
优选的，在所述粗合成气深冷分离过程中，所述粗合成气进口流量为3658-5030kmol/h，温度为24-36℃，压力为26-40bar，所述粗合成气主要组分摩尔百分比为：一氧化碳为22％-33％，氢气为55％-64％,甲烷为8％-15％；被压缩后压力至38bar-56bar。
优选的，在所述粗合成气深冷分离过程中，
粗合成气在深冷换热器第七出口的出口温度为-64.8℃至-97.2℃；
粗合成气在深冷换热器第八出口的出口温度为-148至-152℃；
粗合成气进甲烷深冷分离塔的压力为9.6bar-14.4bar,经分离后塔顶出口气体主要组分摩尔百分比为：一氧化碳为24％-36％，氢气为56％-84％；塔釜气体主要组分摩尔百分比为甲烷为90％-95％。
优选的，在所述粗合成气深冷分离过程中，LNG深冷换热器中LNG出口温度为-162℃；甲烷深冷分离塔塔顶合成气经LNG深冷换热器后压缩至20.8-31.2bar。
优选的，在所述氮气压缩制冷过程中，氮气进口流量为1600-2200kmol/h，温度为15-35℃，压力为2.8bar-4.2bar，二级压缩后压力在22-32bar；
氮气经氮气预冷器出口温度为-67℃至-101℃；
氮气出深冷换热器第六出口的温度为-155.8℃至-148.2℃，气相分率为0.56-0.84；
优选的，在所述氮气压缩制冷过程中，氮气一次气液分离罐气、液出口膨胀压力为2.8-4.2bar；
氮气出深冷换热器第二出口的温度为-86.4℃至-129.6℃。
相对于现有技术，本发明的系统及工艺具有如下优点及有益效果：
(1)本发明优化了粗合成气深冷分离制天然气工艺，新添加的氨吸收制冷单元无需压缩，能耗低，且氨水分离塔塔釜热量将原流程的压缩热利用了起来，且能提供一定的冷量降低混合制冷剂的出口温度与流量，减少了压缩功。实现更高资源利用率同时较小的设备改动降低工厂调整工艺的成本，能广泛应用于传统工艺的优化。
(2)本发明优化了传统煤基富甲烷合成气深冷分离制天然气工艺，能耗降低了25.8％，压缩功热利用率提高了33.40％，混合制冷剂流量下降了15.31％，混合制冷剂用于冷却自身的能量降低至83.5％。
附图说明
图1为传统煤基富甲烷合成气深冷分离制天然气工艺流程图。
图2为本发明煤基富甲烷合成气深冷分离制天然气工艺流程图。
图3为本发明深冷换热器的结构示意图。
具体实施方法
下面结合具体实施例对本发明作进一步具体详细描述，但本发明的实施方式不限于此，对于未特别注明的工艺参数，可参照常规技术进行。
以下实施例采用的系统设置如下：
一种低能耗煤基富甲烷合成气深冷分离制LNG的系统，包括氮气压缩制冷单元、粗合成气深冷分离单元、混合制冷剂压缩制冷单元和氨吸收制冷单元；
所述粗合成气深冷分离单元包括第一压缩机1、第一水冷器2、深冷换热器3、甲烷深冷 分离塔4、粗合成气气液分离罐5、第一膨胀机6、第一节流阀7、LNG深冷器8、第二压缩机9；
所述第一压缩机1与所述第一水冷器2连接，所述第一水冷器2与所述深冷换热器3的第七进口连接，所述深冷换热器3的第七出口与所述甲烷深冷分离塔4的塔釜再沸器连接，所述甲烷深冷分离塔4的塔釜再沸器与所述深冷换热器3第八进口连接，所述深冷换热器3第八出口与粗合成气气液分离罐5连接，所述粗合成气气液分离罐5的顶部、底部分别与所述第一膨胀机6、第一节流阀7连接，所述第一膨胀机6、第一节流阀7与所述甲烷深冷分离塔4连接，所述甲烷深冷分离塔4与所述LNG深冷器8连接，所述LNG深冷器8与所述第二压缩机9连接，所述第二压缩机9与所述深冷换热器3的第三进口连接；
所述氮气压缩制冷单元包括第三压缩机10、氨水分离塔11、第二水冷器12、第四压缩机13、第三水冷器14、氮气预冷器15、所述深冷换热器3、氮气一次气液分离罐16、第二膨胀机17、第二节流阀18和氮气二次气液分离罐19；
所述第三压缩机10与所述氨水分离塔11的塔釜再沸器相连，所述氨水分离塔11的塔釜再沸器与所述第二水冷器12相连，所述第二水冷器12、第四压缩机13、第三水冷器14、氮气预冷器15依次连接，所述氮气预冷器15与所述深冷换热器3的第六进口相连，所述深冷换热器3的第六出口与所述氮气一次气液分离罐16连接，所述氮气一次气液分离罐16的顶部、底部分别与所述第二膨胀机17、第二节流阀18连接，所述第二膨胀机17、第二节流阀18与所述氮气二次气液分离罐19连接，所述氮气二次气液分离罐19的顶部与所述深冷换热器3的第二进口连接，所述深冷换热器3的第二出口与所述氮气预冷器15连接，所述氮气预冷器15与第三压缩机10连接；所述氮气二次气液分离罐19的底部与所述甲烷深冷分离塔4的塔顶冷凝器连接；所述甲烷深冷分离塔4的塔顶冷凝器与所述深冷换热器3的第二进口连接；
所述混合制冷剂压缩制冷单元包括第五压缩机20、所述氨水分离塔11、第四水冷器21、第六压缩机22、第五水冷器23、所述深冷换热器3、混合制冷剂气液分离罐24、第三节流阀 25和第四节流阀26；
所述第五压缩机20与所述氨水分离塔11的塔釜再沸器连接，所述氨水分离塔11的塔釜再沸器、第四水冷器21、第六压缩机22、第五水冷器23依次连接，所述第五水冷器23与所述深冷换热器3的第十一进口连接，所述深冷换热器3的第十一出口与所述混合制冷剂气液分离罐24连接，所述混合制冷剂气液分离罐24的顶部、底部分别与深冷换热器3的第九、第十进口连接，所述深冷换热器3的第九、第十出口分别与第三节流阀25、第四节流阀26连接，所述第三节流阀25与所述深冷换热器3的第五进口连接，所述深冷换热器3的第五出口与深冷换热器3的第四进口连接，所述深冷换热器3的第四出口与第五压缩机20连接；所述第四节流阀26与所述深冷换热器3的第四进口连接；
所述氨吸收制冷单元包括泵27、氨水加热器28、所述氨水分离塔11、第五节流阀29、所述深冷换热器3、第六节流阀30和第六水冷器31；
所述泵27、氨水加热器28、氨水分离塔11依次连接，所述氨水分离塔11的塔顶与第五节流阀29连接，所述第五节流阀29与所述深冷换热器3的第一进口连接，所述深冷换热器3的第一出口与所述第六水冷器31连接，所述第六水冷器31与所述泵27连接；所述氨水分离塔11的塔釜再沸器与氨水加热器28连接，所述氨水加热器28与第六节流阀30连接，所述第六节流阀30与所述第六水冷器31连接。
传统煤基富甲烷合成气深冷分离制天然气工艺流程图见图1；本发明煤基富甲烷合成气深冷分离制天然气工艺流程图见图2，其中深冷换热器的结构示意图见图3。
实施例1
1、氮气压缩制冷单元
初始氮气温度为15℃，压力为2.8bar,流量为1600kmol/h,经压缩机压缩至15.5bar，压缩后的物流进入氨水分离塔塔釜再沸器为塔釜提供热量。提供热量后的氮气再经水冷器降温至33℃进入压缩机压缩至22bar，经水冷器降温至33℃，进入氮气预冷器进行预冷，出口温度为-67℃，再进入深冷换热器进一步降温至-155.8℃,气相分率为0.56，进入氮气一次气 液分离罐进行气液分离，气、液分别膨胀节流至2.8bar，再一次进入氮气二次气液分离罐进行气液分离，其中液相的氮气为甲烷分离塔塔顶提供冷量气化，与氮气二次气液分离罐的气相进行混合，进入深冷换热器进行冷量回收出口温度为-86.4℃，再进入氮气预冷器预冷氮气，出口温度为15℃然后进行循环。
2、粗合成气深冷分离单元
初始粗合成气温度为24℃，压力为26bar，流量为3658kmol/h,组成以摩尔百分比计为27％CO、62％H 2、10.05％CH 4、0.71％C 2H 6和0.24％的N 2与AR。经压缩机压缩到38bar，再经水冷器降温至35℃，进入深冷换热器降温至-64.8℃，-64.8℃的粗合成气进入甲烷深冷分离塔塔釜再沸器提供热量，出塔釜再沸器的粗合成气再进入深冷换热器降温至-148℃，-148℃的粗合成气进入粗合成气气液分离罐进行气液分离，气相与液相分别被膨胀与节流至9.6bar进入甲烷深冷分离塔，经分离后塔顶出口温度-181℃，流量为3251kmol/h，其主要组分摩尔百分比为一氧化碳在30.6％，氢气在69.29％。塔釜出口温度-124℃,流量为407kmol/h，其主要组分摩尔百分比为甲烷在93％。
塔釜的LNG(-124℃)与塔顶的合成气(-181℃)进入LNG深冷器，LNG被冷却至-162℃后进入下一工段，出LNG深冷器合成气温度为-170.1℃经过压缩至20.8bar进入深冷换热器进行冷量回收出口温度为30℃之后进入下一工段。
3、混合制冷剂压缩制冷单元
初始混合制冷剂温度为10℃，压力为1bar，流量为3760kmol/h。组成以摩尔百分比计为28％CH 4、3％N 2、24％丙烷与45％乙烯，经压缩至15bar，进入氨水分离塔塔釜再沸器提供热量，出塔釜的混合制冷剂再经水冷器冷却至33℃，再进入压缩机压缩至16bar，经水冷器冷却至33℃，进入深冷换热器冷却至-21℃，进入混合制冷剂气液分离罐进行气液分离，气相与液相分别进入深冷换热器冷却到-96℃，被冷却到-96℃的罐底液相节流为1bar的气液混合 体，被冷却到-96℃的罐顶气相再进入深冷换热器冷却到-143℃经节流至1bar，循环回深冷换热器为氮气、原料气与本身提供冷量，出深冷换热器后与被冷却到-107℃的罐顶液相节流为1.235bar的气液混合体混合再进入深冷换热器为氮气、原料气与本身提供冷量升温至10℃进行循环。
4、氨吸收制冷单元
初始稀氨水温度为24℃，压力为1bar，流量为5360kmol/h，组成以摩尔百分比计为25％NH 3、75％H 2O，经泵增压到10bar再经氨水加热器升温到109℃进入氨水分离塔进行氨水分离。塔釜稀氨水(氨摩尔分率20％、温度为123℃)进入氨水加热器加热原料出口温度为29℃再进入节流阀节流为1bar。塔顶浓氨水(氨摩尔分率99.99％、温度为25℃)节流为1bar、温度为-29℃，然后进入深冷换热器为混合制冷剂与原料气预冷，降低混合制冷剂出深冷换热器的温度减少压缩功，出深冷换热器后与经热回收后1bar的稀氨水混合进入水冷器冷却为24℃进行循环。
传统工艺流程能耗为21790.89，本实施例工艺流程能耗为16165.75，节能25.8％。传统工艺流程压缩所产生的需要由冷却水冷却的热量为23466.68kW，本实施例工艺流程压缩所产生的需要由冷却水冷却的热量为15956kW，本实施例工艺流程利用压缩所产生的热为5328.92kW，共占总的33.39％，压缩功热利用率提高了33.39％。传统工艺流程混合制冷剂冷却所需冷量23743.5kW，产生冷量26742.25kW，冷却自身占比88.786％，本实施例工艺流程混合制冷剂冷却所需冷量17533.1kW，产生冷量20992.54kW，冷却自身占比83.5％。传统工艺流程混合制冷剂流量为4440kmol/h，本实施例工艺流程混合制冷剂流量为3760kmol/h，减少了15.31％。
实施例2
1、氮气压缩制冷单元
初始氮气温度为24℃，压力为3.5bar,流量为1900kmol/h。经压缩机压缩至15.5bar， 压缩后的物流进入氨水分离塔塔釜再沸器为塔釜提供热量。提供热量后的氮气再经水冷器降温至33℃进入压缩机压缩至27bar，经水冷器降温至33℃，进入氮气预冷器进行预冷，出口温度为-85℃，再进入深冷换热器进一步降温至-151.5℃，气相分率为0.7,进入氮气一次气液分离罐进行气液分离，气、液分别膨胀节流至3.5bar，再一次进入氮气二次气液分离罐进行气液分离，其中液相的氮气为甲烷分离塔塔顶提供冷量气化，与氮气二次气液分离罐的气相进行混合温度为-184℃，进入深冷换热器进行冷量回收出口温度为-100℃，再进入氮气预冷器预冷氮气出口温度为24℃然后进行循环。
2、粗合成气深冷分离单元
初始粗合成气温度为30℃，压力为33bar，流量为4333kmol/h,组成以摩尔百分比计为27％CO、62％H 2、10.05％CH 4、0.71％C 2H 6和0.24％的N 2与AR。经压缩机压缩到47bar，再经水冷器降温至35℃，进入深冷换热器降温至-81℃，-81℃的原料气进入甲烷深冷分离塔塔釜再沸器提供热量，出塔釜再沸器的粗合成气再进入深冷换热器降温至-150℃，-150℃的粗合成气进入粗合成气气液分离罐进行气液分离，气相与液相分别被膨胀与节流至12bar进入甲烷深冷分离塔，塔釜的LNG(-120℃)与塔顶的合成气(-180℃)进入LNG深冷器，LNG被冷却至-162℃后进入下一工段，出LNG深冷器合成气温度为-170℃经过压缩至26.3bar进入深冷换热器进行冷量回收之后进入下一工段。
经分离后塔顶出口温度-180℃，流量为3858kmol/h，其主要组分摩尔百分比为一氧化碳在30.54％，氢气在69.10％。塔釜出口温度-120℃,流量为475kmol/h，其主要组分摩尔百分比为甲烷在93％。
3、混合制冷剂压缩制冷单元
初始混合制冷剂温度为16.1℃，压力为1.2bar,流量为4465kmol/h，组成以摩尔百分比计为28％CH 4、3％N 2、24％丙烷与45％乙烯，经压缩至15bar，进入氨水分离塔塔釜再沸器提供热量，出塔釜的混合制冷剂再经水冷器冷却至33℃，再进入压缩机压缩至20.21bar，经水冷 器冷却至33℃，进入深冷换热器冷却至-26℃，进入混合制冷剂气液分离罐进行气液分离，气相与液相分别进入深冷换热器冷却到-107℃，被冷却到-107℃的罐底液相节流为1.235bar的气液混合体，被冷却到-107℃的罐顶气相再进入深冷换热器冷却到-159℃经节流至1.2bar，温度降为-164℃，循环回深冷换热器为氮气、原料气与本身提供冷量，出深冷换热器后与被冷却到-107℃的罐顶液相节流为1.2bar的气液混合体混合再进入深冷换热器为氮气、原料气与本身提供冷量升温至16.1℃进行循环。
4、氨吸收制冷单元
初始稀氨水温度为30℃，压力为1.2bar，流量为6365kmol/h，组成以摩尔百分比计为25％NH 3、75％H 2O，经泵增压到13bar再经氨水加热器升温到123℃进入氨水分离塔进行氨水分离。塔釜稀氨水(氨摩尔分率20％、温度为135.9℃)进入氨水加热器加热原料出口温度为36.35℃再进入节流阀节流为1.2bar。塔顶浓氨水(氨摩尔分率99.99％、温度为34℃)节流为1.2bar、温度为-29.55℃，然后进入深冷换热器为混合制冷剂与原料气预冷，降低混合制冷剂出深冷换热器的温度减少压缩功，出深冷换热器后与经热回收后1.2bar的稀氨水混合进入水冷器冷却为30℃进行循环。
传统工艺流程能耗为25794.97kW，本实施例工艺流程能耗为19136.21kW，节能25.8％。传统工艺流程压缩所产生的需要由冷却水冷却的热量为27778.68kW，本实施例工艺流程压缩所产生的需要由冷却水冷却的热量为18889.8kW，本实施例工艺流程利用压缩所产生的热为6308.11kW，共占总的33.39％。传统工艺流程混合制冷剂冷却所需冷量28106.37kW，产生冷量31656.14kW，冷却自身占比88.786％，本实施例工艺流程混合制冷剂冷却所需冷量20754.81kW，产生冷量24849.92kW，冷却自身占比83.5％。传统工艺流程混合制冷剂流量为5272kmol/h，本实施例工艺流程混合制冷剂流量为4465kmol/h，减少了15.31％。
实施例3
1、氮气压缩制冷单元
初始氮气温度为35℃，压力为4.2bar,流量为2200kmol/h。经压缩机压缩至18.6bar， 压缩后的物流进入氨水分离塔塔釜再沸器为塔釜提供热量。提供热量后的氮气再经水冷器降温至33℃进入压缩机压缩至32bar，经水冷器降温至33℃，进入氮气预冷器进行预冷，出口温度为-101℃，再进入深冷换热器进一步降温至-148.2℃，气相分率为0.84，进入氮气一次气液分离罐进行气液分离，气、液分别膨胀节流至4.2bar，再一次进入氮气二次气液分离罐进行气液分离，其中液相的氮气为甲烷分离塔塔顶提供冷量气化，与氮气二次气液分离罐的气相进行混合温度为-184℃，进入深冷换热器进行冷量回收出口温度为-129.6℃，再进入氮气预冷器预冷氮气出口温度为35℃然后进行循环。
2、粗合成气深冷分离单元
初始粗合成气温度为36℃，压力为40bar，流量为5030kmol/h,组成以摩尔百分比计为27％CO、62％H 2、10.05％CH 4、0.71％C 2H 6和0.24％的N 2与AR。经压缩机压缩到56bar，再经水冷器降温至35℃，进入深冷换热器降温至-97.2℃，-97.2℃的原料气进入甲烷深冷分离塔塔釜再沸器提供热量，出塔釜再沸器的粗合成气再进入深冷换热器降温至-152℃，-152℃的粗合成气进入粗合成气气液分离罐进行气液分离，气相与液相分别被膨胀与节流至14.4bar进入甲烷深冷分离塔，塔釜的LNG(-114℃)与塔顶的合成气(-177℃)进入LNG深冷器，LNG被冷却至-162℃后进入下一工段，出LNG深冷器合成气温度为-170℃经过压缩至31.2bar进入深冷换热器进行冷量回收之后进入下一工段。
经分离后塔顶出口温度-177℃，流量为4478kmol/h，其主要组分摩尔百分比为一氧化碳在29.4％，氢气在70.20％。塔釜出口温度-114℃,流量为552kmol/h，其主要组分摩尔百分比为甲烷在93％。
3、混合制冷剂压缩制冷单元
初始混合制冷剂温度为20℃，压力为1.5bar,流量为5170kmol/h，组成以摩尔百分比计为28％CH 4、3％N 2、24％丙烷与45％乙烯，经压缩至15bar，进入氨水分离塔塔釜再沸器提供热量，出塔釜的混合制冷剂再经水冷器冷却至33℃，再进入压缩机压缩至24bar，经水冷器冷 却至33℃，进入深冷换热器冷却至-31℃，进入混合制冷剂气液分离罐进行气液分离，气相与液相分别进入深冷换热器冷却到-118℃，被冷却到-118℃的罐底液相节流为1.5bar的气液混合体，被冷却到-118℃的罐顶气相再进入深冷换热器冷却到-163℃经节流至1.5bar，温度降为-165℃，循环回深冷换热器为氮气、原料气与本身提供冷量，出深冷换热器后与被冷却到-118℃的罐顶液相节流为1.5bar的气液混合体混合再进入深冷换热器为氮气、原料气与本身提供冷量升温至20℃进行循环。
4、氨吸收制冷单元
初始稀氨水温度为30℃，压力为1.2bar，流量为7370kmol/h，组成以摩尔百分比计为25％NH 3、75％H 2O，经泵增压到15bar再经氨水加热器升温到130℃进入氨水分离塔进行氨水分离。塔釜稀氨水(氨摩尔分率20％、温度为143℃)进入氨水加热器加热原料出口温度为36℃再进入节流阀节流为1.2bar。塔顶浓氨水(氨摩尔分率99.99％、温度为39℃)节流为1.2bar、温度为-29.55℃，然后进入深冷换热器为混合制冷剂与原料气预冷，降低混合制冷剂出深冷换热器的温度减少压缩功，出深冷换热器后与经热回收后1.2bar的稀氨水混合进入水冷器冷却为30℃进行循环。
传统工艺流程能耗为30960kW，本实施例工艺流程能耗为22972kW，节能25.8％。传统工艺流程压缩所产生的需要由冷却水冷却的热量为33340kW，本实施例工艺流程压缩所产生的需要由冷却水冷却的热量为22670kW，本实施例工艺流程利用压缩所产生的热为15100kW，共占总的33.39％。传统工艺流程混合制冷剂冷却所需冷量33730kW，产生冷量37990kW，冷却自身占比88.786％，本实施例工艺流程混合制冷剂冷却所需冷量24900kW，产生冷量29820kW，冷却自身占比83.5％。传统工艺流程混合制冷剂流量为6104kmol/h，本实施例工艺流程混合制冷剂流量为5170kmol/h，减少了15.31％。

Claims (10)

  1. 一种煤基富甲烷合成气深冷分离制LNG的系统，其特征在于，包括氮气压缩制冷单元、粗合成气深冷分离单元、混合制冷剂压缩制冷单元和氨吸收制冷单元；
    所述粗合成气深冷分离单元包括第一压缩机(1)、第一水冷器(2)、深冷换热器(3)、甲烷深冷分离塔(4)、粗合成气气液分离罐(5)、第一膨胀机(6)、第一节流阀(7)、LNG深冷器(8)、第二压缩机(9)；
    所述第一压缩机(1)与所述第一水冷器(2)连接，所述第一水冷器(2)与所述深冷换热器(3)的第七进口连接，所述深冷换热器(3)的第七出口与所述甲烷深冷分离塔(4)的塔釜再沸器连接，所述甲烷深冷分离塔(4)的塔釜再沸器与所述深冷换热器(3)第八进口连接，所述深冷换热器(3)第八出口与粗合成气气液分离罐(5)连接，所述粗合成气气液分离罐(5)的顶部、底部分别与所述第一膨胀机(6)、第一节流阀(7)连接，所述第一膨胀机(6)、第一节流阀(7)与所述甲烷深冷分离塔(4)连接，所述甲烷深冷分离塔(4)与所述LNG深冷器(8)连接，所述LNG深冷器(8)与所述第二压缩机(9)连接，所述第二压缩机(9)与所述深冷换热器(3)的第三进口连接；
    所述氮气压缩制冷单元包括第三压缩机(10)、氨水分离塔(11)、第二水冷器(12)、第四压缩机(13)、第三水冷器(14)、氮气预冷器(15)、所述深冷换热器(3)、氮气一次气液分离罐(16)、第二膨胀机(17)、第二节流阀(18)和氮气二次气液分离罐(19)；
    所述第三压缩机(10)与所述氨水分离塔(11)的塔釜再沸器相连，所述氨水分离塔(11)的塔釜再沸器与所述第二水冷器(12)相连，所述第二水冷器(12)、第四压缩机(13)、第三水冷器(14)、氮气预冷器(15)依次连接，所述氮气预冷器(15)与所述深冷换热器(3)的第六进口相连，所述深冷换热器(3)的第六出口与所述氮气一次气液分离罐(16)连接，所述氮气一次气液分离罐(16)的顶部、底部分别与所述第二膨胀机(17)、第二节流阀(18)连接，所述第二膨胀机(17)、第二节流阀(18)与所述氮气二次气液分离罐(19)连接，所述氮气二次气液分离罐(19)的顶部与所述深冷换热器(3)的第二进口连接，所述深冷换热器(3)的第二出口与所述氮气预冷器(15)连接，所述氮气预冷器(15)与第三压缩机(10) 连接；所述氮气二次气液分离罐(19)的底部与所述甲烷深冷分离塔(4)的塔顶冷凝器连接；所述甲烷深冷分离塔(4)的塔顶冷凝器与所述深冷换热器(3)的第二进口连接；
    所述混合制冷剂压缩制冷单元包括第五压缩机(20)、所述氨水分离塔(11)、第四水冷器(21)、第六压缩机(22)、第五水冷器(23)、所述深冷换热器(3)、混合制冷剂气液分离罐(24)、第三节流阀(25)和第四节流阀(26)；
    所述第五压缩机(20)与所述氨水分离塔(11)的塔釜再沸器连接，所述氨水分离塔(11)的塔釜再沸器、第四水冷器(21)、第六压缩机(22)、第五水冷器(23)依次连接，所述第五水冷器(23)与所述深冷换热器(3)的第十一进口连接，所述深冷换热器(3)的第十一出口与所述混合制冷剂气液分离罐(24)连接，所述混合制冷剂气液分离罐(24)的顶部、底部分别与深冷换热器(3)的第九、第十进口连接，所述深冷换热器(3)的第九、第十出口分别与第三节流阀(25)、第四节流阀(26)连接，所述第三节流阀(25)与所述深冷换热器(3)的第五进口连接，所述深冷换热器(3)的第五出口与深冷换热器(3)的第四进口连接，所述深冷换热器(3)的第四出口与第五压缩机(20)连接；所述第四节流阀(26)与所述深冷换热器(3)的第四进口连接；
    所述氨吸收制冷单元包括泵(27)、氨水加热器(28)、所述氨水分离塔(11)、第五节流阀(29)、所述深冷换热器(3)、第六节流阀(30)和第六水冷器(31)；
    所述泵(27)、氨水加热器(28)、氨水分离塔(11)依次连接，所述氨水分离塔(11)的塔顶与第五节流阀(29)连接，所述第五节流阀(29)与所述深冷换热器(3)的第一进口连接，所述深冷换热器(3)的第一出口与所述第六水冷器(31)连接，所述第六水冷器(31)与所述泵(27)连接；所述氨水分离塔(11)的塔釜再沸器与氨水加热器(28)连接，所述氨水加热器(28)与第六节流阀(30)连接，所述第六节流阀(30)与所述第六水冷器(31)连接。
  2. 利用权利要求1所述的一种煤基富甲烷合成气深冷分离制LNG系统的工艺，其特征在于，包括氮气压缩制冷过程、粗合成气深冷分离过程、混合制冷剂压缩制冷过程和氨吸收制 冷过程；
    在所述氮气压缩制冷过程中，氮气经第三压缩机压缩后进入氨水分离塔的塔釜再沸器为塔釜提供热量，提供热量后的氮气经第二水冷器冷却后再经第四压缩机与第三水冷器进入氮气预冷器，经预冷后进入深冷换热器的第六进口，经深冷后经过第六出口进入氮气一次气液分离罐进行气液分离，气相、液相分别经第二膨胀机、第二节流阀膨胀节流进入氮气二次气液分离罐再进行气液分离，氮气二次气液分离罐的液相进入甲烷深冷分离塔的塔顶冷凝器，经换热后出塔顶冷凝器与氮气二次气液分离罐的气相相混合，经混合后进入深冷换热器的第二进口，提供一部分冷量后经第二出口进入氮气预冷器，出氮气预冷器后进入第三压缩机进行循环；
    在所述粗合成气深冷分离过程中，粗合成气经第一压缩机与第一水冷器进入深冷换热器的第七进口，换热后经过第七出口进入甲烷深冷分离塔的塔釜再沸器提供热量，出甲烷深冷分离塔的塔釜再沸器后进入深冷换热器第八进口，深冷后经过第八出口进入粗合成气气液分离罐中进行气液分离，气相、液相分别经第一膨胀机、第一节流阀膨胀节流后进入甲烷深冷分离塔，甲烷深冷分离塔塔釜的液相进入LNG深冷器，深冷后进入下一工段，甲烷深冷分离塔塔顶的气相进入LNG深冷器，换热后经第二压缩机进入深冷换热器的第三进口，换热后经过第三出口进入下一工段；
    在所述混合制冷剂压缩制冷过程中，混合制冷剂经第五压缩机压缩后进入氨水分离塔的塔釜再沸器提供热量，再经第四水冷器冷却后再进入第六压缩机压缩，然后经第五水冷器冷却后进入深冷换热器的第十一进口，换热后经过第十一出口进入混合制冷剂气液分离罐进行气液分离，气相与液相分别进入深冷换热器的第九、第十进口，经换热后，液相由深冷换热器的第十出口出来进入第四节流阀，气相由深冷换热器的第九出口出来，经过第三节流阀进入深冷换热器的第五进口，提供冷量后由深冷换热器的第五出口出来的混合制冷剂与经过第四节流阀的混合制冷剂相混合，再共同进入深冷换热器的第四进口，换热后经深冷换热器的第四出口进入第五压缩机进行循环；
    在所述氨吸收制冷过程中，氨水经一台泵进入氨水加热器，加热后进入氨水分离塔进行气液分离，塔顶气相经第五节流阀进入深冷换热器的第一进口，提供冷量后经深冷换热器的第一出口流出，塔釜液相进入氨水加热器，提供热量后流出再经第六节流阀与深冷换热器的第一出口物流混合经第六水冷器冷却后进入泵中进行循环。
  3. 根据权利要求2所述的工艺，其特征在于，
    在所述混合制冷剂压缩制冷过程中，混合制冷剂在进压缩机前的流量为3760-5170kmol/h，温度为10-20℃，压力为1-1.5bar；二级压缩后的压力为16bar-24bar，所述混合制冷剂主要组分摩尔百分比为：甲烷22％-33％，氮气在2％-4％，丙烷在19％-29％，乙烯在36％-54％。
  4. 根据权利要求2所述的工艺，其特征在于，
    在所述混合制冷剂压缩制冷过程中，所述混合制冷剂出深冷换热器第十一出口的温度为-21℃至-31℃；
    所述混合制冷剂出深冷换热器第九出口的温度为-143℃至-163℃，压力为16bar-24bar，经深冷换热器第九出口出来的混合制冷剂节流后的压力为1bar-1.5bar；
    所述混合制冷剂出深冷换热器第十出口温度为-96℃至-118℃，压力为16bar-24bar，经深冷换热器第十出口出来的混合制冷剂节流后的压力在1bar-1.5bar。
  5. 根据权利要求2所述的工艺，其特征在于，在所述氨吸收制冷过程中，所述氨水在进入泵前流量为5360-7370kmol/h，氨水主要组分摩尔百分比为：氨为20％-30％，水为70％-80％；所述氨水进氨水分离塔的压力为10-15bar，温度为109℃-130℃；氨水经氨水分离塔后塔顶出口温度为25-39℃，主要组分摩尔百分比为：氨为99.99％，水为0.01％；塔釜出口温度为123-143℃，主要组分摩尔百分比为：氨为20％，水为80％；节流后压力在1-1.2bar。
  6. 根据权利要求2所述的工艺，其特征在于，在所述粗合成气深冷分离过程中，所述粗合成气进口流量为3658-5030kmol/h，温度为24-36℃，压力为26-40bar，所述粗合成气主要组分摩尔百分比为：一氧化碳为22％-33％，氢气为55％-64％,甲烷为8％-15％；被压缩后压力至38bar-56bar。
  7. 根据权利要求2所述的工艺，其特征在于，在所述粗合成气深冷分离过程中，
    粗合成气在深冷换热器第七出口的出口温度为-64.8℃至-97.2℃；
    粗合成气在深冷换热器第八出口的出口温度为-148℃至-152℃；
    粗合成气进甲烷深冷分离塔的压力为9.6bar-14.4bar,经分离后塔顶出口气体主要组分摩尔百分比为：一氧化碳为24％-36％，氢气为56％-84％；塔釜气体主要组分摩尔百分比为甲烷为90％-95％。
  8. 根据权利要求2所述的工艺，其特征在于，在所述粗合成气深冷分离过程中，LNG深冷换热器中LNG出口温度为-162℃；甲烷深冷分离塔塔顶合成气经LNG深冷换热器后压缩至20.8-31.2bar。
  9. 根据权利要求2所述的工艺，其特征在于，在所述氮气压缩制冷过程中，氮气进口流量为1600-2200kmol/h，温度为15-35℃，压力为2.8bar-4.2bar；二级压缩后压力在22-32bar。
    氮气经氮气预冷器出口温度为-67℃至-101℃；
    氮气出深冷换热器第六出口的温度为-155.8℃至-148.2℃，气相分率为0.56-0.84。
  10. 根据权利要求2所述的工艺，其特征在于，在所述氮气压缩制冷过程中，氮气一次气液分离罐气、液出口膨胀压力为2.8-4.2bar；
    氮气出深冷换热器第二出口的温度为-86.4℃至-129.6℃。
PCT/CN2021/124579 2020-11-05 2021-10-19 一种煤基富甲烷合成气深冷分离制lng的工艺与系统 WO2022095691A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202011220239.1A CN112378168B (zh) 2020-11-05 2020-11-05 一种煤基富甲烷合成气深冷分离制lng的工艺与系统
CN202011220239.1 2020-11-05

Publications (1)

Publication Number Publication Date
WO2022095691A1 true WO2022095691A1 (zh) 2022-05-12

Family

ID=74578150

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/124579 WO2022095691A1 (zh) 2020-11-05 2021-10-19 一种煤基富甲烷合成气深冷分离制lng的工艺与系统

Country Status (2)

Country Link
CN (1) CN112378168B (zh)
WO (1) WO2022095691A1 (zh)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110017664A (zh) * 2019-04-22 2019-07-16 中科瑞奥能源科技股份有限公司 无动力的深冷分离装置与方法
CN114963689A (zh) * 2022-06-22 2022-08-30 中海石油气电集团有限责任公司 一种双循环混合冷剂天然气液化系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112378168B (zh) * 2020-11-05 2024-01-26 华南理工大学 一种煤基富甲烷合成气深冷分离制lng的工艺与系统

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003336965A (ja) * 2002-05-21 2003-11-28 Kawasaki Heavy Ind Ltd Ｌｎｇ冷熱利用による炭酸ガス深冷分離方法および装置
CN202254637U (zh) * 2011-08-03 2012-05-30 成都蜀远煤基能源科技有限公司 煤制气甲烷化后气体深冷分离液化装置
CN106679332A (zh) * 2017-02-17 2017-05-17 查都（上海）科技有限公司 一种提高甲烷深冷分离lng收率的系统
CN109631492A (zh) * 2018-12-13 2019-04-16 西安石油大学 一种采用混合冷剂级联的天然气液化装置及方法
CN110762392A (zh) * 2019-06-25 2020-02-07 杭州杭氧股份有限公司 一种双制冷循环分离煤制合成气中甲烷生产lng和cng的装置
CN112378168A (zh) * 2020-11-05 2021-02-19 华南理工大学 一种煤基富甲烷合成气深冷分离制lng的工艺与系统
CN214250320U (zh) * 2020-11-05 2021-09-21 华南理工大学 一种煤基富甲烷合成气深冷分离制lng系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0667326B1 (en) * 1994-02-04 1997-07-30 Air Products And Chemicals, Inc. Mixed refrigerant cycle for ethylene recovery
CN102267921B (zh) * 2011-05-26 2016-02-24 陈贻盾 一种合成草酰胺连续工艺
CN102654348B (zh) * 2012-05-22 2015-01-28 中国海洋石油总公司 一种焦炉煤气制取液化天然气的方法
CA2813260C (en) * 2013-04-15 2021-07-06 Mackenzie Millar A method to produce lng
CN105737515A (zh) * 2016-03-17 2016-07-06 上海交通大学 基于板式换热器模块化混合制冷剂天然气液化系统及方法
CN207196998U (zh) * 2017-07-25 2018-04-06 华北电力大学（保定） 一种利用化霜废水的高效太阳能热泵气化液化天然气系统
CN111634883A (zh) * 2020-05-29 2020-09-08 西安陕鼓动力股份有限公司 一种合成氨原料气预处理方法及系统

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003336965A (ja) * 2002-05-21 2003-11-28 Kawasaki Heavy Ind Ltd Ｌｎｇ冷熱利用による炭酸ガス深冷分離方法および装置
CN202254637U (zh) * 2011-08-03 2012-05-30 成都蜀远煤基能源科技有限公司 煤制气甲烷化后气体深冷分离液化装置
CN106679332A (zh) * 2017-02-17 2017-05-17 查都（上海）科技有限公司 一种提高甲烷深冷分离lng收率的系统
CN109631492A (zh) * 2018-12-13 2019-04-16 西安石油大学 一种采用混合冷剂级联的天然气液化装置及方法
CN110762392A (zh) * 2019-06-25 2020-02-07 杭州杭氧股份有限公司 一种双制冷循环分离煤制合成气中甲烷生产lng和cng的装置
CN112378168A (zh) * 2020-11-05 2021-02-19 华南理工大学 一种煤基富甲烷合成气深冷分离制lng的工艺与系统
CN214250320U (zh) * 2020-11-05 2021-09-21 华南理工大学 一种煤基富甲烷合成气深冷分离制lng系统

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110017664A (zh) * 2019-04-22 2019-07-16 中科瑞奥能源科技股份有限公司 无动力的深冷分离装置与方法
CN114963689A (zh) * 2022-06-22 2022-08-30 中海石油气电集团有限责任公司 一种双循环混合冷剂天然气液化系统

Also Published As

Publication number Publication date
CN112378168B (zh) 2024-01-26
CN112378168A (zh) 2021-02-19

Similar Documents

Publication Publication Date Title
WO2022095691A1 (zh) 一种煤基富甲烷合成气深冷分离制lng的工艺与系统
CN105865149B (zh) 一种利用液化天然气冷能生产液态空气的方法
CN109140903B (zh) 一种利用液化天然气冷能的空分系统及空气分离方法
CN214250320U (zh) 一种煤基富甲烷合成气深冷分离制lng系统
CN216620451U (zh) 一种lng重整制氢和lng冷能液化氢气一体化系统
CN104807287A (zh) 一种小型天然气液化制冷系统及方法
CN214735563U (zh) 一种油田伴生气生产轻烃和lng的系统
CN103822438A (zh) 一种浅冷轻烃回收工艺方法
CN204508803U (zh) 一种高效分离合成气制取氢气及一氧化碳的装置
CN203310202U (zh) 一种应用于基荷型天然气液化工厂的双混合冷剂液化系统
CN206291621U (zh) 预冷式天然气液化装置及系统
CN204693949U (zh) 一种具有氮甲烷制冷功能的分离富甲烷气装置
CN214250321U (zh) 一种煤基合成气深冷分离制lng冷电联产系统
CN104495751A (zh) 一种高效分离合成气制取氢气及一氧化碳的方法及装置
CN111361013A (zh) 一种混凝土生产预冷预热集成化系统
CN207881278U (zh) 一种基于氩循环的lng冷能利用系统
CN112393526B (zh) 一种煤基合成气深冷分离制lng冷电联产的工艺与系统
CN113670002B (zh) 一种双塔天然气氦回收方法
CN106500458B (zh) 预冷式天然气液化工艺及系统
CN212538461U (zh) 一种带多级分离适用于超富气的丙烷回收装置
CN109631492A (zh) 一种采用混合冷剂级联的天然气液化装置及方法
CN213811330U (zh) 一种lng制备液氢的装置
CN110746259B (zh) 一种带闪蒸分离器的富气乙烷回收方法
CN102645084A (zh) 一种混合冷剂三级制冷制备液化天然气的方法及装置
CN112648033A (zh) 一种利用lng冷能的bog燃气轮机/超临界co2布雷顿/卡琳娜联合循环发电系统

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21888388

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205A DATED 14/08/2023)

122 Ep: pct application non-entry in european phase

Ref document number: 21888388

Country of ref document: EP

Kind code of ref document: A1