CN108533344B - Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof - Google Patents
Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof Download PDFInfo
- Publication number
- CN108533344B CN108533344B CN201810194594.2A CN201810194594A CN108533344B CN 108533344 B CN108533344 B CN 108533344B CN 201810194594 A CN201810194594 A CN 201810194594A CN 108533344 B CN108533344 B CN 108533344B
- Authority
- CN
- China
- Prior art keywords
- working medium
- refrigerant
- heat exchanger
- lng
- power generation
- Prior art date
- Legal status (The legal status 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 status listed.)
- Active
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
- F01K25/10—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours the vapours being cold, e.g. ammonia, carbon dioxide, ether
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K21/00—Steam engine plants not otherwise provided for
-
- 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
- F25C—PRODUCING, WORKING OR HANDLING ICE
- F25C1/00—Producing ice
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
- Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
- Y02P60/85—Food storage or conservation, e.g. cooling or drying
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
The invention discloses a method and a system for generating power and making ice by using nested LNG two-stage parallel cold energy, wherein the method comprises the steps of generating power by a first-stage Rankine cycle, generating power by a second-stage Rankine cycle and making ice, wherein a first working medium in the first-stage Rankine cycle, a second working medium in the second-stage Rankine cycle and a refrigerant in the ice are mutually nested for heat exchange, so that cold energy is fully utilized, high-pressure LNG sequentially passes through the first-stage Rankine cycle and the second-stage Rankine cycle for generating power, respectively exchanges heat with a power generation working medium in a condenser, enters an ice making system for exchanging heat with the refrigerant working medium, finally enters a multi-strand heat exchanger for heating and gasifying into NG by a heat source and is incorporated into a natural gas external transmission pipeline. The heat exchange flow between the two-stage Rankine cycle power generation system and the ice making system is mutually nested, so that cold energy of LNG in the gasification process can be fully utilized, cold energy power generation and ice making are realized, the cold energy utilization efficiency is greatly improved, energy sources are saved, and waste cold energy is effectively utilized.
Description
Technical Field
The invention relates to the technical field of LNG cold energy cascade utilization, in particular to a nested LNG two-stage parallel cold energy power generation and ice making method and system comprising two-stage two-working-medium Rankine cycle power generation and cold energy ice making.
Background
Liquefied Natural Gas (LNG) is Natural Gas (NG) in a liquid form at a low temperature, the storage temperature is about-160 ℃, the storage and transportation are more convenient than NG, however, LNG is usually required to be re-gasified to NG to be widely applied, the cold energy released during LNG gasification is about 840kJ/kg, so that the cold energy stored in LNG is huge, and the recovery of the cold energy has considerable economic and social benefits. If not recycled, this part of the cold energy is usually carried away by the seawater or air in the LNG vaporizer, which in itself causes a huge energy waste. In view of this, the national development and reform committee has proposed research into comprehensive utilization of cold energy of LNG receiving stations as early as 2005.
Various countries in the world are striving to explore ways and methods to increase LNG cold energy utilization, including power generation, air separation, cryogenic drying, ice making, and sea water desalination. The cold energy power generation technology is used as one of the main modes of LNG cold energy utilization, and the basic principle is that LNG is used as a low-temperature cold source in a low-temperature power circulation process, and mechanical work generated by the low-temperature power circulation is used for driving a generator set to generate electric power. As the technology of cold energy is continuously matured, various cold energy utilization schemes have been proposed and implemented, such as direct expansion power generation, low temperature rankine cycle, direct expansion and space division, rankine cycle and direct expansion. Chinese patent CN106150579a discloses a system for generating power by transversely utilizing LNG transcritical cold energy in two stages, wherein the system uses seawater as a heat source, uses LNG cold energy to complete two-stage rankine cycle power generation, and the low-quality cold energy is wasted and the utilization rate is not high; US 6089028 is a closed loop process heat transfer medium to generate electricity. Such a power generation system has a relatively high efficiency compared to direct expansion power generation. But the economic factors such as equipment investment and LNG cold energy utilization efficiency are considered to be further demonstrated. In the second heat exchanger, seawater is used as heat flow, and is directly discharged after heat exchange, so that energy is not well utilized.
Therefore, the LNG cold energy utilization schemes are many, but the existing schemes generally have the problems of low utilization efficiency and the like, so that the cold energy cannot be fully and effectively utilized, and a lot of cold energy is wasted.
Disclosure of Invention
The invention aims at solving the problems in the prior art and provides a nested LNG two-stage parallel cold energy power generation and ice making method and system comprising two-stage two-working medium Rankine cycle power generation and cold energy ice making, so as to comprehensively utilize the cold energy of LNG and fully improve the cold energy utilization rate of the LNG.
The invention aims at solving the problems through the following technical scheme:
a nested LNG two-stage parallel cold energy power generation and ice making method is characterized in that: the method comprises the steps of first-stage Rankine cycle power generation, second-stage Rankine cycle power generation and ice making, wherein a first working medium in the first-stage Rankine cycle power generation, a second working medium in the second-stage Rankine cycle power generation and a refrigerant in the ice making are mutually nested for heat exchange so as to fully utilize cold energy, and the method comprises the following specific steps of:
a. the high-pressure LNG enters a first working medium condenser to exchange heat with a gaseous first working medium from a first turbine generator set, the gaseous first working medium is condensed into a low-temperature liquid state by the high-pressure LNG, the liquid first working medium enters a first working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from an ice making system after being pressurized, then the liquid first working medium enters an evaporator to exchange heat with one strand of second working medium from a second-stage Rankine cycle power generation, then the liquid first working medium enters the first turbine generator set to be changed into a gaseous state after being expanded and cooled to generate power, and the gaseous state returns to the first working medium condenser to exchange heat with the high-pressure LNG again, so that the first-stage Rankine cycle power generation is completed;
b. the high-pressure LNG subjected to heat exchange by the first working medium condenser sequentially enters the second working medium condenser and the NG-refrigerant heat exchanger to be gasified into low-temperature NG, and the low-temperature NG is heated into NG higher than 0 ℃ by the multi-flow heat exchanger and then enters the natural gas external transmission pipeline network; the high-pressure LNG after heat exchange by the first working medium condenser enters the second working medium condenser to exchange heat with the gaseous second working medium from the second turbine generator set, the gaseous second working medium is condensed into low-temperature liquid by the high-pressure LNG, the liquid second working medium enters the second working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from the ice making system after being pressurized, then the liquid second working medium enters the preheater to exchange heat with the heating medium, then the liquid second working medium enters the multi-strand flow heat exchanger to exchange heat with the heating medium from the preheater and the low-temperature NG from the NG-refrigerant heat exchanger, finally the liquid second working medium enters the second turbine generator set to be changed into gaseous state after expansion and cooling power generation and then flows back to the second working medium to exchange heat with the high-pressure LNG after heat exchange by the first working medium, and the second-level Rankine cycle power generation is completed;
c. and c, the first working medium-refrigerant heat exchanger in the step a, the second working medium-refrigerant heat exchanger in the step b and the three strands of refrigerants adopted by the NG-refrigerant heat exchanger are respectively combined with the corresponding first working medium, the second working medium and LNG after heat exchange and cooling, and then flow back to the ice making system to complete the ice making cycle.
The temperature of the high-pressure LNG in the step a is minus 130 ℃ to minus 160 ℃ and the pressure is 6 to 10MPa.
In the step b: the gaseous second working medium from the second turbine generator set is divided into two streams, one stream enters an evaporator of the first-stage Rankine cycle power generation flow and exchanges heat with the first working medium to be condensed into a liquid second working medium, the other stream enters a second working medium condenser and exchanges heat with high-pressure LNG after the heat exchange of the first working medium condenser to be condensed into the liquid second working medium, and the two streams of liquid second working medium are combined into one stream of pressurized and then enter a second working medium-refrigerant heat exchanger to exchange heat with one stream of refrigerant from the ice making system.
The first working medium and the second working medium adopt one or more than two mixed working media of ethylene, ethane, propylene and propane.
The refrigerant adopts CaCl 2 Solution and ethanol.
The heat medium adopted by the preheater in the step b is low-grade heat medium with the temperature lower than 40 ℃.
The system adopted by the method for generating power and making ice by using the nested LNG two-stage parallel cold energy is characterized in that: the system comprises a first-stage Rankine cycle power generation system, a second-stage Rankine cycle power generation system and an ice making system, wherein the first-stage Rankine cycle power generation system comprises a first working medium condenser, a first working medium pump, a first working medium-refrigerant heat exchanger, an evaporator and a first turbine generator set, the first working medium condenser is respectively connected with an LNG inlet pipe and a first working medium outlet pipe of the first turbine generator set, the first working medium condenser is connected with the first working medium-refrigerant heat exchanger through a pipeline with the first working medium pump, and the first working medium-refrigerant heat exchanger is sequentially connected with the evaporator and the first turbine generator set through pipelines; the second-stage Rankine cycle power generation system comprises a second working medium condenser, an NG-refrigerant heat exchanger, a second working medium pump, a second working medium-refrigerant heat exchanger, a preheater, a multi-stream heat exchanger and a second turbine generator set, wherein the second working medium condenser is respectively connected with the first working medium condenser, a second working medium outlet pipe of the second turbine generator set and an LNG inlet of the NG-refrigerant heat exchanger, the second working medium condenser is connected with the second working medium-refrigerant heat exchanger through a pipeline with the second working medium pump, and the second working medium-refrigerant heat exchanger is sequentially connected with the preheater, the multi-stream heat exchanger and the second turbine generator set through pipelines; the refrigerant outlets of the ice making system are respectively connected with the refrigerant inlets of the first working medium-refrigerant heat exchanger, the second working medium-refrigerant heat exchanger and the NG-refrigerant heat exchanger 19 through three refrigerant branches, and the refrigerant outlets of the three refrigerant branches are connected with the refrigerant inlets of the ice making system after being converged through corresponding pipelines.
The second working medium output pipeline is divided into a first branch and a second branch by the splitter, wherein the first branch is connected with a second working medium inlet of the second working medium condenser so that one strand of second working medium exchanges heat with high-pressure LNG after passing through the first working medium condenser in the second working medium condenser, the second branch is connected with a second working medium inlet of an evaporator in the first-stage Rankine cycle power generation system so that the other strand of second working medium exchanges heat with the first working medium in the evaporator and is condensed into a liquid second working medium, a liquid second working medium outlet of the evaporator and a liquid second working medium outlet of the second working medium condenser are respectively connected with an inlet of the confluence device through pipelines so that the two liquid second working mediums are converged into one strand, and an outlet of the confluence device is connected with the liquid second working medium inlet of the second working medium-refrigerant heat exchanger through a pipeline with a second working medium pump so that the low-temperature liquid second working medium exchanges heat with a refrigerant from the ice making system.
A first working medium branch with a first valve connected in parallel with the first working medium outlet pipeline and the first working medium inlet pipeline of the first turbine generator set is arranged between the first working medium outlet pipeline and the first working medium inlet pipeline; and a second working medium branch with a second valve connected in parallel with the second working medium outlet pipeline and the second working medium inlet pipeline of the second turbine generator set is arranged between the second working medium outlet pipeline and the second working medium inlet pipeline.
A refrigerant pump is arranged on a converging pipeline in front of a refrigerant inlet of the ice making system.
Compared with the prior art, the invention has the following advantages:
according to the invention, an embedded two-stage parallel Rankine cycle power generation system is utilized, LNG cold energy is fully utilized, LNG is subjected to heat exchange with working media of the two-stage Rankine cycle power generation system and refrigerants of an ice making system, and finally heat exchange is carried out in a multi-flow heat exchanger, so that NG is heated to a relatively high temperature and enters an output pipeline network; the whole process system fully utilizes LNG cold energy, the cold energy utilization efficiency is greatly improved, the energy is saved, the waste cold energy is effectively utilized, the economic benefit is very high, the heat exchange pipes of the heat exchanger, the condenser and the heater adopt unique high-efficiency special pipes such as internal wave external thread pipes, internal or external or internal channel pipes and the like, the heat exchange equipment size is greatly reduced, and the energy saving effect is very obvious; meanwhile, the process system is simple in flow, safe and reliable.
Drawings
FIG. 1 is a flow chart of a method for generating electricity and making ice by using nested LNG two-stage parallel cold energy.
Wherein: 1-LNG inlet pipe; 2-a first working medium pump; 3-a first working medium-refrigerant heat exchanger; 4-an evaporator; 5-a first valve; 6-a first turbine generator set; 7-a first working medium condenser; 8, a confluence device; 9-a second working medium pump; 10-a second working medium-refrigerant heat exchanger; 11-a preheater; 12-a heating medium inlet pipe; 13-multi-stream heat exchanger; 14-a heating medium outlet pipe; 15-NG outlet pipe; 16-a second valve; 17-a second turbine generator set; 18-a shunt; 19-NG-refrigerant heat exchanger; 20-a second working medium condenser; 21-an ice making system; 22-refrigerant pump.
Description of the embodiments
The invention is further described below with reference to the drawings and examples.
As shown in fig. 1: the method comprises the steps of first-stage Rankine cycle power generation, second-stage Rankine cycle power generation and ice making, wherein a first working medium in the first-stage Rankine cycle power generation, a second working medium in the second-stage Rankine cycle power generation and a refrigerant in the ice making are mutually nested and heat exchanged to fully utilize the cold energy, and the method comprises the following specific steps of: a. the high-pressure LNG with the temperature of minus 130 ℃ to minus 160 ℃ and the pressure of 6 to 10MPa enters a first working medium condenser to exchange heat with a gaseous first working medium from a first turbine generator set, the gaseous first working medium is condensed into a low-temperature liquid state by the high-pressure LNG, the liquid first working medium enters a first working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from an ice making system after being pressurized, then the liquid first working medium enters an evaporator to exchange heat with one strand of second working medium from a second-stage Rankine cycle power generation, then the liquid first working medium enters the first turbine generator set to be changed into a gaseous state after being expanded and cooled to generate power, and then the gaseous first working medium returns to the first working medium condenser to exchange heat with the high-pressure LNG again, so that the first-stage Rankine cycle power generation is completed; b. the high-pressure LNG subjected to heat exchange by the first working medium condenser sequentially enters the second working medium condenser and the NG-refrigerant heat exchanger to be gasified into low-temperature NG, and the low-temperature NG is heated into NG higher than 0 ℃ by the multi-flow heat exchanger and then enters the natural gas external transmission pipeline network; the high-pressure LNG after heat exchange by the first working medium condenser enters the second working medium condenser to exchange heat with the gaseous second working medium from the second turbine generator set, the gaseous second working medium is condensed into low-temperature liquid by the high-pressure LNG, the liquid second working medium enters the second working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from the ice making system after being pressurized, then the liquid second working medium enters the preheater to exchange heat with the heating medium, then the liquid second working medium enters the multi-strand flow heat exchanger to exchange heat with the heating medium from the preheater and the low-temperature NG from the NG-refrigerant heat exchanger, finally the liquid second working medium enters the second turbine generator set to be changed into gaseous state after expansion and cooling power generation and then flows back to the second working medium to exchange heat with the high-pressure LNG after heat exchange by the first working medium, and the second-level Rankine cycle power generation is completed; c. and c, the first working medium-refrigerant heat exchanger in the step a, the second working medium-refrigerant heat exchanger in the step b and the three strands of refrigerants adopted by the NG-refrigerant heat exchanger are respectively combined with the corresponding first working medium, the second working medium and LNG after heat exchange and cooling, and then flow back to the ice making system to complete the ice making cycle.
In the method, the gaseous second working medium from the second turbine generator set is divided into two streams, one stream enters an evaporator of the first-stage Rankine cycle power generation process and exchanges heat with the first working medium to be condensed into a liquid second working medium, the other stream enters a second working medium condenser and exchanges heat with high-pressure LNG subjected to heat exchange by the first working medium condenser to be condensed into the liquid second working medium, and the two streams of liquid second working medium are combined into one stream of pressurized and then enter a second working medium-refrigerant heat exchanger to exchange heat with one stream of refrigerant from the ice making system. The first working medium and the second working medium adopt one or more than two of ethylene, ethane, propylene and propane, and the first working medium and the second working medium can be the same working medium or different working media. CaCl is adopted as the refrigerant 2 Solution, ethanol, but not limited thereto. In addition, the heat medium adopted by the preheater is low-grade heat medium below 40 ℃, and the heat source can be sea water, but the heat source is not limited to sea water, other low-grade heat sources such as circulating water below 40 ℃ and air can be utilized, and the heat source can be combined with practical solar energy utilization, industrial waste heat utilization and the like.
A nested LNG two-stage parallel cold energy power generation and ice making system comprises a first-stage Rankine cycle power generation system, a second-stage Rankine cycle power generation system and an ice making system 21. The first-stage Rankine cycle power generation system comprises a first working medium condenser 7, a first working medium pump 2, a first working medium-refrigerant heat exchanger 3, an evaporator 4 and a first turbine generator set 6, wherein the first working medium condenser 7 is respectively connected with an LNG inlet pipe 1 and a first working medium outlet pipe of the first turbine generator set 6, the first working medium condenser 7 is connected with the first working medium-refrigerant heat exchanger 3 through a pipeline with the first working medium pump 2, and the first working medium-refrigerant heat exchanger 3 is sequentially connected with the evaporator 4 and the first turbine generator set 6 through pipelines; the specific conditions are as follows: the working medium outlet of the first turbine generator set 6 is connected with the first working medium inlet of the first working medium condenser 7 through a first working medium outlet pipe to send the first working medium steam from the first turbine generator set 6 into the first working medium condenser 7 to exchange heat and condense with high-pressure LNG to form a low-temperature liquid first working medium, the first working medium outlet of the first working medium condenser 7 is connected with the working medium inlet of the first working medium-refrigerant heat exchanger 3 through a pipeline with the first working medium pump 2 to exchange heat between the low-temperature liquid first working medium and the refrigerant from the ice making system 21, the working medium outlet of the first working medium-refrigerant heat exchanger 3 is connected with the working medium inlet of the evaporator 4 through a pipeline to exchange heat between the first working medium entering the evaporator 4 and the second working medium from the second stage Rankine cycle power generation system, the working medium outlet of the evaporator 4 is connected with the working medium inlet of the first turbine generator set 6 through a pipeline to enable the liquid first working medium entering the first turbine generator set 6, and the liquid first working medium enters the first working medium condenser 7 again after being expanded and cooled to become gas to complete the first stage Rankine power generation cycle. The second-stage Rankine cycle power generation system comprises a second working medium condenser 20, an NG-refrigerant heat exchanger 19, a second working medium pump 9, a second working medium-refrigerant heat exchanger 10, a preheater 11, a multi-stream heat exchanger 13 and a second turbine generator set 17, wherein the second working medium condenser 20 is respectively connected with the first working medium condenser 7, a second working medium outlet pipe of the second turbine generator set 17 and an LNG inlet of the NG-refrigerant heat exchanger 19, the second working medium condenser 20 is connected with the second working medium-refrigerant heat exchanger 10 through a pipeline with the second working medium pump 9, and the second working medium-refrigerant heat exchanger 10 is sequentially connected with the preheater 11, the multi-stream heat exchanger 13 and the second turbine generator set 17 through pipelines; the specific conditions are as follows: the LNG inlet of the second working medium condenser 20 is connected with the LNG outlet pipe of the first working medium condenser 7, the LNG outlet pipe of the second working medium condenser 20 is connected with the LNG inlet of the NG-refrigerant heat exchanger 19, the LNG outlet pipe of the NG-refrigerant heat exchanger 19 is connected with the LNG inlets of the multi-strand flow heat exchanger 13, so that LNG subjected to heat exchange with the first working medium sequentially enters the second working medium condenser 20, the NG-refrigerant heat exchanger 19 and the multi-strand flow heat exchanger 13 to be heated into NG, and then enters a natural gas external transmission pipeline network through the NG outlet pipe 15; in the second-stage Rankine cycle power generation system, a flow divider 18 is arranged at a working medium outlet of the second turbine generator unit 17 to divide a second working medium output pipeline into a first branch and a second branch, the first branch is connected with a second working medium inlet of the second working medium condenser 20 so that one strand of second working medium exchanges heat with high-pressure LNG passing through the first working medium condenser 7 in the second working medium condenser 20 again, the second branch is connected with a second working medium inlet of an evaporator 4 in the first-stage Rankine cycle power generation system so that the other strand of second working medium exchanges heat with the first working medium in the evaporator 4 and then condenses into a liquid second working medium, a liquid second working medium outlet of the evaporator second working medium and a liquid second working medium outlet of the second working medium condenser 20 are respectively connected with an inlet of a confluence device 8 through pipelines so that two strands of liquid second working medium are converged into one strand, an outlet of the confluence device 8 is connected with a liquid second working medium inlet of a second working medium-refrigerant heat exchanger 10 through a pipeline with a second working medium pump 9 so that the low-temperature liquid second working medium exchanges heat with a refrigerant from a refrigerating system 21, a working medium outlet of the second working medium-heat exchanger 10 is connected with an inlet of a preheater 11, a plurality of heat medium inlets of the preheater 11 can be connected with a heat medium inlet pipe 12 of the evaporator 11 so that the second working medium inlet of the preheater 11 can flow into the heat exchanger of the second working medium generator set through a heat exchanger 17, and the heat exchange device of the second working medium flows into the heat exchanger 17 from the second working medium heat exchange device 17 through the second working medium heat exchange device 17; the heat medium outlet of the preheater 11 is connected with the heat medium inlet of the multi-stream heat exchanger 13 through a pipeline, and the heat medium outlet of the multi-stream heat exchanger 13 is provided with a heat medium outlet pipe 14. The refrigerant outlet of the ice making system 21 is respectively connected with refrigerant inlets of the first working medium-refrigerant heat exchanger 3, the second working medium-refrigerant heat exchanger 10 and the NG-refrigerant heat exchanger 19 through three refrigerant branches, so that one refrigerant exchanges heat with the first working medium at the first working medium-refrigerant heat exchanger 3 for cooling, one refrigerant exchanges heat with the second working medium at the second working medium-refrigerant heat exchanger 10 for cooling, and the last refrigerant exchanges heat with the LNG at the NG-refrigerant heat exchanger 19 for cooling; the refrigerant outlet of the first working medium-refrigerant heat exchanger 3, the refrigerant outlet of the second working medium-refrigerant heat exchanger 10 and the refrigerant outlet of the NG-refrigerant heat exchanger 19 are respectively connected with the refrigerant inlet of the ice making system 21 through three refrigerant loops so as to make the three refrigerants after heat exchange and temperature reduction merge again, the refrigerant inlet of the ice making system 21 is provided with a refrigerant pump 22, and the cooled refrigerant is sent into the ice making system 21 through the refrigerant pump 22 to complete ice making circulation.
In addition, a first working medium branch with a first valve 5 connected in parallel with a first working medium outlet pipeline and a first working medium inlet pipeline of the first turbine generator set 6 are arranged between the first working medium outlet pipeline and the first working medium inlet pipeline, the first valve 5 is in a closed state under the normal working condition of the system, and the abnormal condition is opened to protect the first turbine generator set 6; a second working medium branch with a second valve 16 connected in parallel with the second working medium outlet pipeline and the second working medium inlet pipeline of the second turbine generator set 17 is arranged between the second working medium outlet pipeline and the second working medium inlet pipeline, the second valve 16 is in a closed state under the normal working condition of the system, and the abnormal condition is opened to protect the second turbine generator set 17. Meanwhile, the heat exchange pipes of the heat exchanger, the condenser and the heater adopted in the system adopt special-shaped pipes with unique high efficiency such as internal wave external thread pipes, internal or external or internal and external channel pipes, and the like, so that the size of heat exchange equipment is greatly reduced, and the energy-saving effect is very obvious.
The process of the present invention is further illustrated by the following examples.
Examples
As shown in fig. 1, the system adopted by the whole process consists of a first-stage rankine cycle power generation system, a second-stage rankine cycle power generation system and an ice making system. During operation, high-pressure LNG with the temperature of minus 130 ℃ to minus 160 ℃ and the pressure of 6-10 MPa, which is input through the LNG inlet pipe 1, sequentially passes through the first-stage Rankine cycle power generation system, the second-stage Rankine cycle power generation and ice making system 21, is gasified into low-temperature NG with the temperature of minus 15 ℃, continuously passes through the multi-strand heat exchanger 13 and is heated into NG with the temperature of more than 0 ℃ and the pressure of 6-10 MPa, and enters the natural gas external transmission pipe network.
First-stage Rankine cycle power generation system: ethylene is used as a first working medium, gaseous ethylene with normal pressure and temperature of minus 96 ℃ from a first turbine generator set 6 is condensed into liquid ethylene with normal pressure and temperature of minus 96 ℃ by high-pressure LNG with temperature of minus 130 ℃ to minus 160 ℃ and pressure of 6-10 MPa in a first working medium condenser 7, the liquid ethylene is pressurized to 1-3 MPa by a first working medium pump 2 and then is sent into a first working medium-refrigerant heat exchanger 3 to exchange heat with a refrigerant with temperature of minus 10 ℃ from an ice making system 21, the temperature of the refrigerant is reduced to minus 35 ℃ from minus 10 ℃, the temperature of the first working medium is increased to minus 50 ℃ and then enters an evaporator 4 to exchange heat with propylene from a second-stage Rankine cycle power generation system, then the first working medium enters the first turbine generator set 6, and enters the first working medium condenser 7 to exchange heat with the high-pressure LNG again after being expanded and cooled, so that one Rankine cycle is completed.
A second stage rankine cycle power generation system: propylene is used as a second working medium, gaseous propylene with normal pressure and temperature of minus 42 ℃ from a second turbine generator set 17 is divided into two streams, one stream enters a second working medium condenser 20 and is condensed into liquid propylene with temperature of minus 42 ℃ by high-pressure LNG with temperature of minus 102 ℃ and pressure of 6-10 MPa, the other stream enters an evaporator 4 in a first-stage Rankine cycle power generation system and is condensed into liquid second working medium with temperature of minus 42 ℃ by heat exchange with first working medium ethylene, the two streams are combined into one stream by a confluence device 8, the two streams are pressurized to 1-3 MPa by a second working medium pump 9 and then are sent into a second working medium-refrigerant heat exchanger 10, the temperature of propylene exchanges heat with refrigerant with temperature of minus 10 ℃ from an ice making system 21, the temperature of propylene rises to minus 15 ℃ from minus 15 ℃, the temperature of the refrigerant is reduced to minus 35 ℃, the propylene is heated by seawater through a plurality of preheaters 11, enters a plurality of stream heat exchangers 13 and exchanges heat with the seawater from the preheaters 11, and NG with temperature of minus 15 ℃ after the heat exchange with a Rankine refrigerant heat exchanger 19 is 6-10 MPa, and the two streams enter the second turbine generator set 17, and the cycle power generation is completed.
Ice making system: the refrigerant with the temperature of minus 10 ℃ coming out of the ice making system 21 is divided into three strands, wherein one strand of refrigerant exchanges heat with the first working medium in the first working medium-refrigerant heat exchanger 3 and cools down, the other strand of refrigerant exchanges heat with the second working medium in the second working medium-refrigerant heat exchanger 10 and cools down, the last strand of refrigerant exchanges heat with LNG in the NG-refrigerant heat exchanger 19 and cools down, the three strands of refrigerant are converged again after being cooled down to minus 35 ℃ through heat exchange, and the three strands of refrigerant are sent into the ice making system 21 through the refrigerant pump 22 to complete ice making circulation.
According to the invention, an embedded two-stage parallel Rankine cycle power generation system is utilized, LNG cold energy is fully utilized, LNG is subjected to heat exchange with working media of the two-stage Rankine cycle power generation system and refrigerants of an ice making system, and finally heat exchange is carried out in a multi-flow heat exchanger, so that NG is heated to a relatively high temperature and enters an output pipeline network; the whole process system fully utilizes LNG cold energy, the cold energy utilization efficiency is greatly improved, the energy is saved, the waste cold energy is effectively utilized, the economic benefit is very high, the heat exchange pipes of the heat exchanger, the condenser and the heater adopt unique high-efficiency special pipes such as internal wave external thread pipes, internal or external or internal channel pipes and the like, the heat exchange equipment size is greatly reduced, and the energy saving effect is very obvious; meanwhile, the process system is simple in flow, safe and reliable.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any changes, modifications, substitutions, combinations, and simplifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention; the technology not related to the invention can be realized by the prior art.
Claims (10)
1. A nested LNG two-stage parallel cold energy power generation and ice making method is characterized in that: the method comprises the steps of first-stage Rankine cycle power generation, second-stage Rankine cycle power generation and ice making, wherein a first working medium in the first-stage Rankine cycle power generation, a second working medium in the second-stage Rankine cycle power generation and a refrigerant in the ice making are mutually nested for heat exchange so as to fully utilize cold energy, and the method comprises the following specific steps of:
a. the high-pressure LNG enters a first working medium condenser to exchange heat with a gaseous first working medium from a first turbine generator set, the gaseous first working medium is condensed into a low-temperature liquid state by the high-pressure LNG, the liquid first working medium enters a first working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from an ice making system after being pressurized, then the liquid first working medium enters an evaporator to exchange heat with one strand of second working medium from a second-stage Rankine cycle power generation, then the liquid first working medium enters the first turbine generator set to be changed into a gaseous state after being expanded and cooled to generate power, and the gaseous state returns to the first working medium condenser to exchange heat with the high-pressure LNG again, so that the first-stage Rankine cycle power generation is completed;
b. the high-pressure LNG subjected to heat exchange by the first working medium condenser sequentially enters the second working medium condenser and the NG-refrigerant heat exchanger to be gasified into low-temperature NG, and the low-temperature NG is heated into NG higher than 0 ℃ by the multi-flow heat exchanger and then enters the natural gas external transmission pipeline network; the high-pressure LNG after heat exchange by the first working medium condenser enters the second working medium condenser to exchange heat with the gaseous second working medium from the second turbine generator set, the gaseous second working medium is condensed into low-temperature liquid by the high-pressure LNG, the liquid second working medium enters the second working medium-refrigerant heat exchanger to exchange heat with one strand of refrigerant from the ice making system after being pressurized, then the liquid second working medium enters the preheater to exchange heat with the heating medium, then the liquid second working medium enters the multi-strand flow heat exchanger to exchange heat with the heating medium from the preheater and the low-temperature NG from the NG-refrigerant heat exchanger, finally the liquid second working medium enters the second turbine generator set to be changed into gaseous state after expansion and cooling power generation and then flows back to the second working medium to exchange heat with the high-pressure LNG after heat exchange by the first working medium, and the second-level Rankine cycle power generation is completed;
c. and c, the first working medium-refrigerant heat exchanger in the step a, the second working medium-refrigerant heat exchanger in the step b and the three strands of refrigerants adopted by the NG-refrigerant heat exchanger are respectively combined with the corresponding first working medium, the second working medium and LNG after heat exchange and cooling, and then flow back to the ice making system to complete the ice making cycle.
2. The method for generating power and making ice by using nested LNG two-stage parallel cold energy according to claim 1, wherein the method comprises the following steps: the temperature of the high-pressure LNG in the step a is minus 130 ℃ to minus 160 ℃ and the pressure is 6 to 10MPa.
3. The method for generating power and making ice by using nested LNG two-stage parallel cold energy according to claim 1, wherein the method comprises the following steps: in the step b: the gaseous second working medium from the second turbine generator set is divided into two streams, one stream enters an evaporator of the first-stage Rankine cycle power generation flow and exchanges heat with the first working medium to be condensed into a liquid second working medium, the other stream enters a second working medium condenser and exchanges heat with high-pressure LNG after the heat exchange of the first working medium condenser to be condensed into the liquid second working medium, and the two streams of liquid second working medium are combined into one stream of pressurized and then enter a second working medium-refrigerant heat exchanger to exchange heat with one stream of refrigerant from the ice making system.
4. The method for generating power and making ice by using nested LNG two-stage parallel cold energy according to claim 1, wherein the method comprises the following steps: the first working medium and the second working medium adopt one or more than two mixed working media of ethylene, ethane, propylene and propane.
5. The method for generating power and making ice by using nested LNG two-stage parallel cold energy according to claim 1, wherein the method comprises the following steps: the refrigerant adopts CaCl 2 Solution or ethanol.
6. The method for generating power and making ice by using nested LNG two-stage parallel cold energy according to claim 1, wherein the method comprises the following steps: the heat medium adopted by the preheater in the step b is low-grade heat medium with the temperature lower than 40 ℃.
7. The system adopted by the method for generating power and making ice by using the nested LNG two-stage parallel cold energy according to any one of claims 1 to 6, is characterized in that: the system comprises a first-stage Rankine cycle power generation system, a second-stage Rankine cycle power generation system and an ice making system (21), wherein the first-stage Rankine cycle power generation system comprises a first working medium condenser (7), a first working medium pump (2), a first working medium-refrigerant heat exchanger (3), an evaporator (4) and a first turbine generator set (6), the first working medium condenser (7) is respectively connected with an LNG inlet pipe (1) and a first working medium outlet pipe of the first turbine generator set (6), the first working medium condenser (7) is connected with the first working medium-refrigerant heat exchanger (3) through a pipeline with the first working medium pump (2), and the first working medium-refrigerant heat exchanger (3) is sequentially connected with the evaporator (4) and the first turbine generator set (6) through pipelines; the second-stage Rankine cycle power generation system comprises a second working medium condenser (20), an NG-refrigerant heat exchanger (19), a second working medium pump (9), a second working medium-refrigerant heat exchanger (10), a preheater (11), a multi-stream heat exchanger (13) and a second turbine generator set (17), wherein the second working medium condenser (20) is respectively connected with an LNG outlet pipe of the first working medium condenser (7), a second working medium outlet pipe of the second turbine generator set (17) and an LNG inlet of the NG-refrigerant heat exchanger (19), the second working medium condenser (20) is connected with the second working medium-refrigerant heat exchanger (10) through a pipeline with the second working medium pump (9), and the second working medium-refrigerant heat exchanger (10) is sequentially connected with the preheater (11), the multi-stream heat exchanger (13) and the second turbine generator set (17) through pipelines; the refrigerant outlet of the ice making system (21) is respectively connected with the refrigerant inlets of the first working medium-refrigerant heat exchanger (3), the second working medium-refrigerant heat exchanger (10) and the NG-refrigerant heat exchanger (19) through three refrigerant branches, and the refrigerant outlets of the first working medium-refrigerant heat exchanger (3), the second working medium-refrigerant heat exchanger (10) and the NG-refrigerant heat exchanger (19) are connected with the refrigerant inlet of the ice making system (21) after being converged through corresponding pipelines.
8. The system adopted by the method for generating power and making ice by using the nested LNG two-stage parallel cold energy according to claim 7 is characterized in that: the second turbine generator set (17) is characterized in that a flow divider (18) is arranged at a working medium outlet of the second turbine generator set (17), the flow divider (18) divides a second working medium output pipeline into a first branch and a second branch, the first branch is connected with a second working medium inlet of a second working medium condenser (20) so that one strand of the second working medium is subjected to heat exchange with high-pressure LNG (liquefied natural gas) after passing through the first working medium condenser (7) in the second working medium condenser (20), the second branch is connected with a second working medium inlet of an evaporator (4) in the first-stage Rankine cycle power generation system so that the other strand of the second working medium is subjected to heat exchange with the first working medium in the evaporator (4) and then is condensed into a liquid second working medium, a liquid second working medium outlet of the evaporator and a liquid second working medium outlet of the second working medium condenser (20) are respectively connected with an inlet of a confluence device (8) through pipelines so that the liquid second working medium of the confluence device (8) is converged into one strand, and an outlet of the confluence device (8) is connected with a second inlet of a second working medium (10) through a pipeline with a second pump (9) so that the second working medium is subjected to heat exchange with a low-temperature refrigerant from the second system.
9. The system adopted by the method for generating power and making ice by using the nested LNG two-stage parallel cold energy according to claim 7 is characterized in that: a first working medium branch with a first valve (5) connected in parallel with a first working medium outlet pipeline and a first working medium inlet pipeline of the first turbine generator set (6) are arranged between the first working medium outlet pipeline and the first working medium inlet pipeline; a second working medium branch with a second valve (16) connected in parallel with the second working medium outlet pipeline and the second working medium inlet pipeline of the second turbine generator set (17) is arranged between the second working medium outlet pipeline and the second working medium inlet pipeline.
10. The system adopted by the method for generating power and making ice by using the nested LNG two-stage parallel cold energy according to claim 7 is characterized in that: a refrigerant pump (22) is arranged on a converging pipeline in front of a refrigerant inlet of the ice making system (21).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810194594.2A CN108533344B (en) | 2018-03-09 | 2018-03-09 | Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810194594.2A CN108533344B (en) | 2018-03-09 | 2018-03-09 | Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108533344A CN108533344A (en) | 2018-09-14 |
| CN108533344B true CN108533344B (en) | 2023-08-15 |
Family
ID=63485672
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810194594.2A Active CN108533344B (en) | 2018-03-09 | 2018-03-09 | Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108533344B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109294647B (en) * | 2018-09-17 | 2021-08-13 | 广州智光节能有限公司 | Purification system of natural gas |
| CN109826684B (en) * | 2019-01-03 | 2022-05-10 | 上海海事大学 | Low-pressure organic Rankine cycle power generation system capable of efficiently utilizing low-temperature cold energy |
| CN110486627B (en) * | 2019-07-24 | 2020-06-19 | 西安交通大学 | Poly-generation system based on LNG cold energy utilization |
| CN110761864B (en) * | 2019-11-08 | 2021-12-07 | 江苏科技大学 | Novel cold energy comprehensive utilization system of liquefied natural gas power container ship |
| CN115217540B (en) * | 2021-04-19 | 2024-06-21 | 中国石油化工集团有限公司 | Power generation and refrigeration house ice-making co-production system for recycling LNG cold energy through step coupling |
| CN113280663B (en) * | 2021-05-14 | 2023-04-25 | 江苏科技大学 | Compact intermediate medium carburetor with cold energy utilization and power generation system formed by same |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013035822A1 (en) * | 2011-09-09 | 2013-03-14 | 国立大学法人佐賀大学 | Steam power cycle system |
| CN104948246A (en) * | 2015-06-18 | 2015-09-30 | 东北大学 | Method for capturing carbon dioxide in mineral smelting waste gas by making use of liquefied natural gas (LNG) cold energy |
| CN104989473A (en) * | 2015-05-27 | 2015-10-21 | 上海交通大学 | Power generation system and generating method based on same |
| CN106285808A (en) * | 2016-08-31 | 2017-01-04 | 航天晨光股份有限公司 | A kind of cold energy of liquefied natural gas utilization system and method |
-
2018
- 2018-03-09 CN CN201810194594.2A patent/CN108533344B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013035822A1 (en) * | 2011-09-09 | 2013-03-14 | 国立大学法人佐賀大学 | Steam power cycle system |
| CN104989473A (en) * | 2015-05-27 | 2015-10-21 | 上海交通大学 | Power generation system and generating method based on same |
| CN104948246A (en) * | 2015-06-18 | 2015-09-30 | 东北大学 | Method for capturing carbon dioxide in mineral smelting waste gas by making use of liquefied natural gas (LNG) cold energy |
| CN106285808A (en) * | 2016-08-31 | 2017-01-04 | 航天晨光股份有限公司 | A kind of cold energy of liquefied natural gas utilization system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108533344A (en) | 2018-09-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108533344B (en) | Nested LNG two-stage parallel cold energy power generation and ice making method and system thereof | |
| CN110374838B (en) | Transcritical carbon dioxide energy storage system and method based on LNG (liquefied Natural gas) cold energy utilization | |
| US10138810B2 (en) | Method and apparatus for power storage | |
| CN106939802B (en) | Utilize the power generation of mixed working fluid step and remaining cooling capacity output system and method for LNG cold energy | |
| CN103362579A (en) | Two-stage expansion power generation device and method for recovering liquefied natural gas cold energy | |
| CN109579432B (en) | Natural gas and electric power interconnection peak shaving system utilizing low-temperature liquefaction for energy storage | |
| CN116247700B (en) | Liquid air energy storage system based on LNG cold energy utilization | |
| CN111121390A (en) | Liquefied air energy storage power generation system coupled with steam-water system of coal-fired power generating unit | |
| CN211903494U (en) | Liquefied air energy storage power generation system coupled with steam-water system of coal-fired power generating unit | |
| CN110864498B (en) | LNG cold energy cascade utilization device and method | |
| CN108331627B (en) | Single-cycle two-stage LNG cold energy power generation and ice making method and system | |
| KR102429318B1 (en) | LNG Regasification process and liquid air energy storage system | |
| CN117722819B (en) | Novel liquefied air energy storage system of self-balancing type coupling LNG cold energy | |
| CN210396824U (en) | Natural gas residual pressure cold energy power generation cascade utilization system | |
| CN106194302B (en) | A kind of LNG cold energy utilization system and method | |
| CN104373165A (en) | System for generating power through liquefied natural gas cold energy | |
| CN203035472U (en) | Generating system utilizing hydrocarbon mixture as working medium to recover liquefied natural gas cold energy | |
| CN117190625A (en) | Sectional type cold energy recycling and cascade utilization system based on LNG shallow and medium cryogenic temperature zone | |
| CN110185506B (en) | Pressure energy comprehensive utilization system of natural gas pressure regulating station | |
| CN111173581A (en) | LNG cold energy comprehensive utilization system | |
| CN202928199U (en) | A system capable of providing cold and heat stepwise by employing natural gas pressure energy | |
| CN213478413U (en) | Intermediate steam extraction type liquefied natural gas cold energy power generation system based on pressure distribution | |
| CN212272325U (en) | LNG cold energy comprehensive utilization system | |
| CN211174246U (en) | Multistage L NG cold energy power generation and comprehensive utilization system | |
| CN110715504B (en) | Residual pressure power generation liquefaction system of high-pressure natural gas |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |