CN114923295B - Variable working condition adjusting method for two-stage series-connection intermediate heat exchange turbine expander - Google Patents

Variable working condition adjusting method for two-stage series-connection intermediate heat exchange turbine expander Download PDF

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Publication number
CN114923295B
CN114923295B CN202210735389.9A CN202210735389A CN114923295B CN 114923295 B CN114923295 B CN 114923295B CN 202210735389 A CN202210735389 A CN 202210735389A CN 114923295 B CN114923295 B CN 114923295B
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turboexpander
series
outlet end
turbine expander
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CN114923295A (en
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熊联友
王广海
邵东方
杨坤
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Beijing Zhongke Fu Hai Low Temperature Technology Co ltd
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Beijing Zhongke Fu Hai Low Temperature Technology Co ltd
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    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0005—Light or noble gases
    • F25J1/0007—Helium
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/40—Fluid line arrangements
    • F25B41/42—Arrangements for diverging or converging flows, e.g. branch lines or junctions
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0035—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work
    • F25J1/0037—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work of a return 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0201—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration
    • F25J1/0202—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration in a quasi-closed internal refrigeration 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0221—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using the cold stored in an external cryogenic component in an open refrigeration loop
    • F25J1/0224—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using the cold stored in an external cryogenic component in an open refrigeration loop in combination with an internal quasi-closed refrigeration 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0245—Different modes, i.e. 'runs', of operation; Process control
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0245—Different modes, i.e. 'runs', of operation; Process control
    • F25J1/0247—Different modes, i.e. 'runs', of operation; Process control start-up of the process
    • 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
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—Nitrogen
    • 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
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention relates to a variable working condition adjusting method of a two-stage series-connection intermediate heat exchange turboexpander, which relates to the field of refrigerating systems and comprises a compressor, a plurality of groups of heat exchangers connected with the compressor and two series-connection turboexpanders, wherein the heat exchangers are connected in series and are connected with the turboexpanders in parallel, one group of heat exchangers is connected between the two turboexpanders in series, a group of bypass loop is added between the two turboexpanders, a bypass adjusting valve is connected to the bypass loop so as to adjust the gas flow in the bypass loop, and the bypass loop is connected with the heat exchangers or the turboexpanders. The invention has the advantage of avoiding low refrigeration capacity caused by long-term operation of the primary turbine expander at low rotation speed.

Description

Variable working condition adjusting method for two-stage series-connection intermediate heat exchange turbine expander
Technical Field
The invention relates to the technical field of refrigeration systems, in particular to a variable working condition adjusting method of a two-stage series-connection intermediate heat exchange turbine expander.
Background
The turbo expander is one of the important core components of the cryogenic gas separation and liquefaction device. The refrigerating capacity of the turbine expander is related to the inlet temperature and expansion ratio of the turbine expander, the isentropic enthalpy drop is related to the inlet pressure and temperature under the condition that the outlet pressure of the expander is constant, the higher the temperature is, the larger the expansion ratio is, the larger the enthalpy drop is, wherein the influence of the temperature on the isentropic enthalpy drop is larger, so that the turbine expander expands at high temperature, and the refrigerating capacity obtained by the turbine expander is larger. In addition, the operating speed of the turboexpander is approximately proportional to the square root of the enthalpy drop, the greater the enthalpy drop, the higher the operating speed.
For low-temperature devices with low required refrigeration temperature, a multi-stage turboexpander is generally adopted to perform expansion refrigeration in different temperature areas, the turboexpander working in a higher temperature area expands at a high temperature to obtain larger refrigeration capacity, and the expander working in a low temperature area expands at a low temperature to obtain lower refrigeration temperature.
For the common low-temperature refrigerant, the lower the boiling point is, the higher the enthalpy drop will be when the refrigerant expands at high temperature, the larger the refrigerating capacity is, for example, the boiling point of hydrogen and helium refrigerant is lower than that of natural gas, air, nitrogen and other refrigerant, the higher enthalpy drop will be when the refrigerant expands at high temperature, therefore, the refrigeration cycle composed of low-boiling-point low-temperature refrigerant gas is adopted, two series turbo expanders are usually arranged, the refrigeration is realized by adopting the mode of two-stage expansion and intermediate heat exchange cooling, the intermediate heat exchange is beneficial to improving the working temperature of the high Wen Wenou expander on one hand, and the working temperature of the expander in the low-temperature area is beneficial to being reduced on the other hand. For example, the helium liquefying device, the hydrogen liquefying device and the like shown in fig. 1 adopt a modified Claude liquefying cycle to refrigerate based on a mode of two-stage expansion and intermediate heat exchange cooling, and the flow arrangement is beneficial to obtaining large refrigerating capacity and lower refrigerating temperature, and can reduce enthalpy drop of a single expander in series to avoid excessive rotating speed caused by excessive enthalpy drop.
For a two-stage series-connection intermediate heat exchange refrigerating system, in the cooling process, as the parts such as a heat exchanger and a turbine expander in the system are gradually cooled from normal temperature, the inlet temperature of the expander is expanded at high temperature deviating from the design working condition in the cooling stage, and the heat exchange is performed in the middle, so that the heat capacity of the heat exchanger is larger in the cooling process, the cooling is slow, and the inlet temperature of the second-stage turbine expander is often similar to the inlet temperature of the first-stage turbine expander; on the other hand, the inlet pressure of the second stage turboexpander is lower than the first stage due to the series expansion, which is the first stage turboexpander outlet pressure minus the along-the-path flow resistance. Based on the reasons of inlet temperature and pressure, for the first-stage and second-stage turboexpanders which are designed according to the design working conditions, if the designed working speed is to be reached under the working conditions of the initial cooling stage, the required mass flow of the second-stage turboexpander is larger than that of the first-stage turboexpander, but because the turboexpanders are arranged in series, the mass flow of the first-stage and second-stage turboexpanders is the same, namely the flow required by the first-stage and second-stage turboexpanders in series in the cooling process is not matched, the mismatch of the flow can lead to that the second-stage turboexpander can easily reach the working speed in the initial cooling stage, the first-stage turboexpander can only operate at a low speed in the initial cooling stage, and the speed of the first-stage turboexpander can gradually rise along with the reduction of the inlet temperature of the second-stage turboexpander only when the system is cooled to a low enough temperature.
Therefore, in the cooling process, as the serial turboexpander meets the requirement of the flow mismatch required by the working at the design rotating speed, the primary turboexpander works for a long time in a state lower than the working rotating speed, the refrigerating capacity is greatly reduced, and the cooling time is greatly prolonged.
Therefore, in order to overcome the above disadvantages, a method for adjusting the variable working condition of the two-stage series-connection intermediate heat exchange turbine expander is needed.
Disclosure of Invention
First, the technical problem to be solved
The invention aims to solve the technical problems that: in the conventional two-stage series turboexpander, the one-stage turboexpander works at a working rotation speed lower than a working rotation speed for a long time in the cooling process of a low-temperature system, and the cooling efficiency is low.
(II) technical scheme
In order to solve the technical problems, the invention provides a variable working condition adjusting method of a two-stage series-connection intermediate heat exchange turboexpander, which comprises a compressor, a plurality of groups of heat exchangers connected with the compressor and two series-connection turboexpanders, wherein the plurality of groups of heat exchangers are connected in series, the plurality of groups of heat exchangers are connected with the two turboexpanders in parallel, the two turboexpanders are sequentially a first-stage turboexpander and a second-stage turboexpander according to the hot gas flow direction, the two turboexpanders are connected with one group of heat exchangers in series through a gas circuit pipeline, a bypass loop is added between the two turboexpanders, the inlet end of the bypass loop is connected with the outlet end of the first-stage turboexpander, a bypass adjusting valve is arranged on the bypass loop to adjust the gas flow in the bypass loop, and the bypass outlet end loop is connected with the heat exchangers or the turboexpanders.
As a further illustration of the present invention, it is preferred that the primary turboexpander outlet be connected to the centrally located heat exchanger inlet and that the bank of heat exchanger outlet be connected to the secondary turboexpander inlet.
As a further illustration of the invention, it is preferred that the outlet end of the bypass circuit communicates with the low pressure inlet end of the intermediate heat exchanger.
As a further illustration of the invention, it is preferred that the outlet end of the bypass circuit communicates with the low pressure outlet end of the intermediate heat exchanger.
As a further illustration of the present invention, it is preferred that the outlet end of the bypass circuit is in communication with the outlet end of the second stage turboexpander.
As a further illustration of the present invention, the outlet end of the bypass circuit is preferably in direct communication with the inlet end of the second stage turboexpander such that the gas bypass from the outlet portion of the first stage turboexpander merges with the inlet gas stream from the second stage turboexpander before entering the second stage turboexpander.
(III) beneficial effects
The technical scheme of the invention has the following advantages:
according to the invention, the gas flow of the first-stage and second-stage turboexpanders is regulated by the bypass regulating valve, so that the first-stage and second-stage turboexpanders work at different mass flow rates, the required design working rotating speed is conveniently achieved, the low refrigerating capacity caused by long-term operation of the first-stage turboexpander at a low rotating speed is avoided, and the higher refrigerating capacity of the first-stage turboexpander and the second-stage turboexpander is always maintained in the cooling process, so that the cooling time of a low-temperature system is reduced.
Drawings
FIG. 1 is a flow chart of the operation of a two-stage series intermediate heat exchange turboexpander of the prior art;
FIG. 2 is a flow chart of the general conceptual design of the present invention;
FIG. 3 is a flow chart of a conventional pre-cooling claort helium liquefaction with liquid nitrogen;
FIG. 4 is a workflow diagram of an embodiment of the present invention;
FIG. 5 is a second workflow diagram of an embodiment of the present invention;
FIG. 6 is a three-work flow chart of an embodiment of the invention;
fig. 7 is a fourth operational flow diagram of an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
A variable working condition adjusting method of a two-stage series-connection intermediate heat exchange turbine expander is shown in fig. 2, and comprises a compressor, a plurality of groups of heat exchangers connected with the compressor and two series-connection turbine expanders, wherein the two series-connection turbine expanders are a primary turbine expander and a secondary turbine expander in sequence according to the flow direction of hot gas, five groups of heat exchangers are connected in series and in parallel with the turbine expanders, and the five groups of heat exchangers are HEX1, HEX2, HEX3, HEX4 and HEX5 along the flow direction of high-pressure gas. The two turbine expanders are connected in series with the HEX3 heat exchanger in the middle, namely, the gas outlet end of the first-stage expander is connected with the gas inlet end of the HEX3 heat exchanger, and the gas outlet end of the HEX3 heat exchanger is connected with the gas inlet end of the second-stage expander. A set of bypass loop is added between the two turbo-expanders, the inlet end of the bypass loop is communicated with the outlet end of the primary turbo-expander, a bypass regulating valve is connected to the bypass loop to regulate the gas flow in the bypass loop, and the bypass loop is connected with the heat exchanger or the turbo-expander.
As shown in fig. 3, belongs to the traditional flow of the liquid nitrogen precooling claort helium liquefaction. Taking a helium liquefier with a liquefaction rate of 40L/h as an example, the liquefier self (without subsequent load such as cooling of liquid helium storage Dewar) begins to cool for about 10 hours to realize liquefaction of helium, and the specific cooling process is as follows:
at the initial stage of cooling, liquid nitrogen precooling is started, a cooling loop control valve CV2 is started, the circulating helium gas gradually transfers the cold energy provided by the liquid nitrogen precooling to each stage of heat exchanger under the condition of liquid nitrogen precooling, and the first stage of heat exchanger HEX1 is cooled fast due to direct cooling of liquid nitrogen, but the later stages of heat exchangers are cooled slowly.
When the HEX1 high-pressure helium outlet is cooled to about 200K, an air inlet valve CV1 of the expander is opened, and the primary turbine expander 1 starts to work; the temperature of the inlet of the first-stage turboexpander 1 is about 200K, and the temperature of the inlet of the second-stage turboexpander 2 is about 260K because the temperature of the later-stage heat exchangers is reduced slowly.
Compared with the working states of the first-stage turboexpander 1 and the second-stage turboexpander 2 at the moment, the temperature of the inlet of the second-stage turboexpander 2 is relatively high, the volume flow is large, the enthalpy drop after expansion is large, and the rotating speed of the second-stage turboexpander 2 can be easily increased to 20,0000rpm (the normal working rotating speed of a typical 40L/h helium liquefier expander is about 20,0000rpm). On the contrary, the inlet temperature of the primary turboexpander 1 is relatively low, the volume flow is small, and the enthalpy drop after expansion is small, so that the primary turboexpander 1 can only work at a lower rotation speed, for example 10,0000rpm, under the condition that the secondary turboexpander 2 is ensured to work at a designed rotation speed. At the moment, the primary turbine expander 1 has small refrigerating capacity due to insufficient expansion work, and the cooling rate of the helium liquefier is reduced.
With the gradual cooling of the helium liquefier, the inlet temperature of the second-stage turboexpander 2 is gradually reduced and is finally lower than the inlet temperature of the first-stage turboexpander 1, the rotating speed of the first-stage turboexpander 1 is gradually increased in the process, and finally, the two turboexpanders reach the design rotating speed.
In the cooling process, the inlet conditions of the first-stage turboexpander 1 and the second-stage turboexpander 2 deviate from the design working condition, so that the expansion refrigeration capacity of the first-stage turboexpander 1 in the cooling process is insufficient, the cooling is slower, and the cooling time of the 40L/h helium liquefier under the working condition is about 10 hours to realize the liquefaction of helium.
Embodiment one: as shown in fig. 4, a bypass circuit is added based on the original line of fig. 3, and the outlet end of the bypass circuit communicates with the low pressure inlet end of the HEX3 heat exchanger, and then the gas is circulated in the cold flow direction. In the initial stage of cooling, the opening degree of the bypass regulating valve CV5 is regulated, the cooling of the intermediate heat exchanger is facilitated, the gas flow entering the second-stage turboexpander 2 is reduced, the first-stage turboexpander 1 and the second-stage turboexpander 2 can be controlled to work at the designed rotating speed, thus the two turboexpanders work at the maximum refrigerating capacity, the cooling rate is effectively accelerated, and the cooling time can be reduced to about 6 hours.
Embodiment two: as shown in FIG. 5, the outlet end of the bypass loop is communicated with the low-pressure outlet end of the intermediate HEX3 heat exchanger, and in this way, both the primary turboexpander 1 and the secondary turboexpander 2 can be controlled to work at the designed rotating speed, so that both the turboexpanders work at the maximum refrigerating capacity, and the cooling rate is effectively accelerated.
Embodiment III: as shown in FIG. 6, the outlet end of the bypass loop is communicated with the outlet end of the second-stage turboexpander 2, and in this way, both the first-stage turboexpander 1 and the second-stage turboexpander 2 can be controlled to work at the designed rotation speed, so that both the two turboexpanders work at the maximum refrigerating capacity, and the cooling rate is effectively accelerated.
Embodiment four: as shown in FIG. 7, the outlet end of the bypass loop is directly communicated with the inlet end of the second-stage turboexpander 2, so that part of gas at the outlet of the first-stage turboexpander 1 is bypassed and is converged with the gas flow at the inlet of the second-stage turboexpander 2 and then enters the second-stage turboexpander 2, and the first-stage turboexpander 1 and the second-stage turboexpander 2 can be controlled to work at the designed rotating speeds in the mode, so that the two turboexpanders work at the maximum refrigerating capacity, and the cooling rate is effectively accelerated.
In summary, although only one bypass loop is added, the invention can make the first-stage and second-stage turboexpanders work under different mass flow rates, so as to be convenient for respectively reaching the required design working rotation speed, avoid the low refrigeration capacity caused by long-term operation of the first-stage turboexpander 1 under low rotation speed, and make the first-stage and second-stage turboexpanders always maintain higher refrigeration capacity in the cooling process, thereby reducing the cooling time of a low-temperature system. For a low-temperature system with precooling, the inlet temperature of the primary turboexpander 1 is lower than the inlet temperature of the secondary turboexpander 2 in the initial stage of the cooling process, and partial gas with lower temperature after the primary turboexpander 1 expands is bypassed and then returned to the low-pressure inlet of the intermediate heat exchanger, so that the cooling of the intermediate heat exchanger is accelerated, the rotating speeds of the primary and secondary turboexpanders are well matched as soon as possible, and the cooling process is accelerated.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (4)

1. A variable working condition adjusting method of a two-stage series-connection intermediate heat exchange turbine expander comprises a compressor, a plurality of groups of heat exchangers connected with the compressor and two series-connection turbine expanders, wherein the plurality of groups of heat exchangers are connected in series, the plurality of groups of heat exchangers are connected with the two turbine expanders in parallel, and the variable working condition adjusting method is characterized in that the variable working condition adjusting method comprises the steps of sequentially arranging a first-stage turbine expander and a second-stage turbine expander according to the flow direction of hot gas, and is characterized in that: the two turbine expanders are connected in series with one group of heat exchangers through a gas circuit pipeline, the outlet end of the first-stage turbine expander is connected with the inlet end of the heat exchanger positioned in the middle, and the outlet end of the group of heat exchangers is connected with the inlet end of the second-stage turbine expander; a set of bypass loop is added between two turboexpanders, the inlet end of the bypass loop is connected with the outlet end of the primary turboexpander, and a bypass regulating valve is arranged on the bypass loop to regulate the gas flow in the bypass loop and reduce the gas flow entering the secondary turboexpander, and the bypass outlet end loop is connected with a heat exchanger or the turboexpander so that the primary turboexpander and the secondary turboexpander reach the required design working rotation speed and the cooling time of a low-temperature system is reduced.
2. The method for adjusting the variable working condition of the two-stage series-connection intermediate heat exchange turbine expander according to claim 1, wherein the method comprises the following steps of: the outlet end of the bypass loop is communicated with the low-pressure inlet end of the intermediate heat exchanger.
3. The method for adjusting the variable working condition of the two-stage series-connection intermediate heat exchange turbine expander according to claim 1, wherein the method comprises the following steps of: the outlet end of the bypass loop is communicated with the low-pressure outlet end of the intermediate heat exchanger.
4. The method for adjusting the variable working condition of the two-stage series-connection intermediate heat exchange turbine expander according to claim 1, wherein the method comprises the following steps of: the outlet end of the bypass loop is communicated with the outlet end of the two-stage turbine expander.
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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05322344A (en) * 1992-05-26 1993-12-07 Kobe Steel Ltd Method and apparatus for controlling operating state of turbine type expansion machine in freezer device
JPH06101918A (en) * 1992-09-18 1994-04-12 Hitachi Ltd Cryogenic refrigerator
CN1133392A (en) * 1994-10-25 1996-10-16 乔治·克劳德方法的研究开发空气股份有限公司 Method and device for expanding and compressing at least one kind of gaseous stock fluid
JPH08285395A (en) * 1995-04-10 1996-11-01 Kobe Steel Ltd Device for liquefying herium
JP2007017010A (en) * 2005-07-05 2007-01-25 Railway Technical Res Inst Method and apparatus for controlling refrigerating capacity of turbine type refrigerator
CN109690216A (en) * 2016-12-08 2019-04-26 川崎重工业株式会社 Unstrpped gas liquefying plant and its control method
CN109764637A (en) * 2018-12-28 2019-05-17 中国科学院理化技术研究所 A kind of novel helium liquefier flow path device
CN110657633A (en) * 2019-10-21 2020-01-07 北京中科富海低温科技有限公司 Hydrogen liquefaction system
CN215216756U (en) * 2021-05-26 2021-12-17 中国科学院理化技术研究所 Turbine expansion low-temperature system capable of quickly cooling and quickly rewarming
CN113883827A (en) * 2021-10-29 2022-01-04 四川空分设备(集团)有限责任公司 Helium purification and liquefaction system
CN113983760A (en) * 2021-10-29 2022-01-28 四川空分设备(集团)有限责任公司 Helium ultra-low temperature purification and liquefaction system

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05322344A (en) * 1992-05-26 1993-12-07 Kobe Steel Ltd Method and apparatus for controlling operating state of turbine type expansion machine in freezer device
JPH06101918A (en) * 1992-09-18 1994-04-12 Hitachi Ltd Cryogenic refrigerator
CN1133392A (en) * 1994-10-25 1996-10-16 乔治·克劳德方法的研究开发空气股份有限公司 Method and device for expanding and compressing at least one kind of gaseous stock fluid
JPH08285395A (en) * 1995-04-10 1996-11-01 Kobe Steel Ltd Device for liquefying herium
JP2007017010A (en) * 2005-07-05 2007-01-25 Railway Technical Res Inst Method and apparatus for controlling refrigerating capacity of turbine type refrigerator
CN109690216A (en) * 2016-12-08 2019-04-26 川崎重工业株式会社 Unstrpped gas liquefying plant and its control method
CN109764637A (en) * 2018-12-28 2019-05-17 中国科学院理化技术研究所 A kind of novel helium liquefier flow path device
CN110657633A (en) * 2019-10-21 2020-01-07 北京中科富海低温科技有限公司 Hydrogen liquefaction system
CN215216756U (en) * 2021-05-26 2021-12-17 中国科学院理化技术研究所 Turbine expansion low-temperature system capable of quickly cooling and quickly rewarming
CN113883827A (en) * 2021-10-29 2022-01-04 四川空分设备(集团)有限责任公司 Helium purification and liquefaction system
CN113983760A (en) * 2021-10-29 2022-01-28 四川空分设备(集团)有限责任公司 Helium ultra-low temperature purification and liquefaction system

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