CN111852684A - Waste heat recovery power generation system - Google Patents

Waste heat recovery power generation system Download PDF

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Publication number
CN111852684A
CN111852684A CN201910365176.XA CN201910365176A CN111852684A CN 111852684 A CN111852684 A CN 111852684A CN 201910365176 A CN201910365176 A CN 201910365176A CN 111852684 A CN111852684 A CN 111852684A
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China
Prior art keywords
working medium
mixed working
heat exchange
exchange device
heat
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Pending
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CN201910365176.XA
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Chinese (zh)
Inventor
冯金勇
张子建
胡璐
李静芬
刘江楠
顾智超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Qiyao Heavy Industry Co ltd
Shanghai Marine Diesel Engine Research Institute
711th Research Institute of CSIC
Original Assignee
Shanghai Qiyao Heavy Industry Co ltd
711th Research Institute of CSIC
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Priority to CN201910365176.XA priority Critical patent/CN111852684A/en
Publication of CN111852684A publication Critical patent/CN111852684A/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
    • F02G5/02—Profiting from waste heat of exhaust gases
    • 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
    • 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
    • F01K25/106—Ammonia
    • 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
    • F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
    • F25B15/02—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas
    • F25B15/04—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas the refrigerant being ammonia evaporated from aqueous solution
    • 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
    • F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
    • F25B15/02—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas
    • F25B15/06—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas the refrigerant being water vapour evaporated from a salt solution, e.g. lithium bromide
    • 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
    • F25B27/00—Machines, plants or systems, using particular sources of energy
    • F25B27/02—Machines, plants or systems, using particular sources of energy using waste heat, e.g. from internal-combustion engines
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/27—Relating to heating, ventilation or air conditioning [HVAC] technologies
    • Y02A30/274—Relating to heating, ventilation or air conditioning [HVAC] technologies using waste energy, e.g. from internal combustion engine
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/62—Absorption based systems
    • Y02B30/625—Absorption based systems combined with heat or power generation [CHP], e.g. trigeneration
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • 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)
  • Materials Engineering (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Abstract

The invention provides a waste heat recovery power generation system. The system comprises: the main machine generates flue gas; the first heat exchange device is communicated with the main machine; the gas-liquid separation device is communicated with the first heat exchange device; the expander generator set is communicated with the steam outlet of the gas-liquid separation device and is used for generating power by utilizing the steam; the mixing device is used for mixing the second mixed working medium and the steam with the reduced temperature; the refrigerating system is communicated with the mixing device and is used for liquefying the mixed second mixed working medium and steam into a first mixed working medium; the first mixed working medium is a mixture at least comprising two working media, wherein the boiling point of at least one working medium is lower than 100 ℃. Compared with the prior art in which water is used as a working medium, the steam for power generation can be generated under the condition of low temperature of flue gas, and the utilization rate of heat is further improved.

Description

Waste heat recovery power generation system
Technical Field
The invention relates to the technical field of ship energy conservation, in particular to a waste heat recovery power generation system.
Background
The International Maritime Organization (IMO) establishes two ship energy efficiency standards, the "ship energy efficiency design index" (EEDI) and the "ship energy efficiency management plan" (SEEMP). This is the first mandatory legal document specifically for international maritime greenhouse gas emission reduction and has been implemented in 2013, 1 month and 1 day on international vessels sailing at 400 total tons and above with keels.
The thermal efficiency of the known diesel engine is generally 45-50%. The cooling water takes away heat by external heat exchange by about 20-25%. The heat carried away by the exhaust gas is about 25-30%. Currently, two-stroke low speed diesel engines have the highest efficiency of all thermal engines-close to 50%, but still have more than half of the fuel energy unutilized.
The exhaust afterheat recovering power generating technology for main engine belongs to the secondary heat energy utilizing technology, and can raise the fuel oil utilizing rate and lower installed power. Therefore, the technology of generating power by using the exhaust waste heat of the marine main engine is an important technical direction for reducing CO2 emission and EEDI. At present, steam Rankine cycle power generation and Organic Rankine Cycle (ORC) power generation are mainly used in medium and low temperature exhaust waste heat recovery power generation modes in industry, and different modes are applied to different fields or occasions according to the cycle characteristics of the power generation modes. The exhaust gas of the marine diesel engine is mostly low-temperature heat sources at 260-350 ℃, and the operating load of the main engine and the exhaust parameters of the marine diesel engine change along with the change of sea conditions in the operation process of the marine diesel engine, so that the exhaust gas waste heat recovery system is easy to deviate from the design working condition. At present, ships divided abroad have a steam Rankine cycle power generation technology, and the technology has the following defects in ship exhaust waste heat recovery power generation:
(1) For a medium-low temperature heat source, water or organic matters are used as working media, water vapor or organic matter vapor is evaporated at a constant temperature, evaporation equipment is limited by node temperature difference, the temperature of exhaust cannot be reduced to an ideal range, and waste heat cannot be fully recovered;
(2) when the operation load of the host deviates from the design working condition of the waste heat recovery power generation system, the waste heat recovery efficiency of the system is reduced, and the waste heat cannot be fully recovered;
(3) the system has low waste heat recovery cold-electricity conversion efficiency which is only 15 to 25 percent for medium and low temperature, and the rest heat is discharged in a form of cooling water at 35 to 45 ℃ and cannot be recovered.
Aiming at the defects existing in the ship main engine waste heat recovery, the technical problem to be solved is to provide the waste heat recovery power generation system which can recover the middle and low temperature heat sources and has higher waste heat recovery efficiency.
Disclosure of Invention
To at least partially solve the above problems, the present invention provides a waste heat recovery power generation system. This waste heat recovery power generation system includes:
a main machine, which generates flue gas;
the first heat exchange device is communicated with the main machine and is used for exchanging heat between a first mixed working medium and the flue gas so as to heat the first mixed working medium to generate first steam;
The gas-liquid separation device is communicated with the first heat exchange device and is used for separating a second mixed working medium generated by heating the first mixed working medium from the first steam;
the expander generator set is communicated with the first steam outlet of the gas-liquid separation device and is used for generating power by utilizing the first steam;
the mixing device is respectively communicated with a second mixed working medium outlet of the gas-liquid separation device and an outlet of the expander generator set and is used for mixing the second mixed working medium and the first steam with the reduced temperature into a gas-liquid mixture;
the refrigerating system is communicated with the mixing device and is used for condensing the gas-liquid mixture so as to liquefy the gas-liquid mixture into the first mixed working medium;
the first mixed working medium is a mixture at least comprising two working media, wherein the boiling point of at least one of the working media is lower than 100 ℃.
In an embodiment, the second mixed working medium is a mixture of the first mixed working medium and the working medium with the lowest boiling point, and the second mixed working medium is partially evaporated into the first steam, and the first steam is formed by evaporation of the first mixed working medium and the working medium with the lowest boiling point.
In an embodiment, the first mixed working fluid is ammonia water.
In an embodiment, the first mixed working fluid comprises at least one of refrigerants R401A, R402B, R405A, R407C and R409A.
In an embodiment, the refrigeration system further comprises a second heat exchange device, wherein a hot side of the second heat exchange device is located between the mixing device and the refrigeration system, and a cold side of the second heat exchange device is located between the first heat exchange device and the refrigeration system.
In an embodiment, the gas-liquid separation device further comprises a third heat exchange device, wherein a hot side of the third heat exchange device is located between the gas-liquid separation device and the mixing device, and a cold side of the third heat exchange device is located between a cold side of the second heat exchange device and the first heat exchange device.
In an embodiment, a pressure regulating valve is arranged between the hot side of the third heat exchange device and the mixing device, and is used for controlling the flow rate of the second mixed working medium input into the mixing device.
In an embodiment, the system further comprises a frequency conversion device, wherein the frequency conversion device is connected with the expander generator set and used for controlling the expander generator set.
In an embodiment, the refrigeration system comprises:
The heat exchanger comprises a first heat exchange device, a second heat exchange device, a first condenser, a second condenser and a second heat exchange device, wherein the first condenser is connected with the second heat exchange device, the hot side of the first condenser is communicated with the hot side of the second heat exchange device and is used for allowing the gas-liquid mixture passing through the second heat exchange device to flow through, a third mixed working medium flows through the cold side of the first condenser, the first condenser is used for performing heat exchange on the third mixed working medium and the gas-liquid mixture, and the third mixed working medium is heated to form high-pressure low-temperature second steam and a fourth mixed working medium;
the second condenser is connected with the first condenser, low-temperature return water flows through the cold side of the second condenser, the hot side of the second condenser is communicated with the cold side of the first condenser, high-pressure low-temperature second steam flows through the hot side of the second condenser, and the second steam and the low-temperature return water exchange heat to be condensed into a fourth mixed working medium with high pressure and low temperature;
the first throttling valve is connected with the condenser and used for depressurizing the fourth mixed working medium with high pressure and low temperature into the fourth mixed working medium with low pressure and low temperature;
the evaporator is connected with the first throttling valve and used for receiving the fourth mixed working medium with low pressure and low temperature input by the first throttling valve, the fourth mixed working medium is evaporated in the evaporator and absorbs the heat of the cold water working medium in the evaporator to be changed into the second steam, and the cold water working medium further releases heat and is cooled into a cold water working medium with lower temperature;
The absorber is respectively connected with the first condenser and the evaporator, and the absorber is used for mixing the second steam and the fourth mixed working medium to form the third mixed working medium.
In an embodiment, the refrigeration system further comprises:
and an inlet of a hot side of the fourth heat exchange device is connected with the first condenser, an outlet of the hot side of the fourth heat exchange device is connected with the absorber, an inlet of a cold side of the fourth heat exchange device is connected with the absorber, an outlet of the cold side of the fourth heat exchange device is connected with the first condenser, and the fourth heat exchange device is used for carrying out heat exchange on the fourth mixed working medium and the third mixed working medium.
In an embodiment, the third mixed working fluid in the refrigeration system comprises at least one non-azeotropic mixture of ammonia water, water-lithium chloride, water-lithium iodide, water-lithium bromide, ammonia-lithium nitrate and ammonia-sodium thiocyanate.
According to the waste heat recovery power generation system, the energy carried by the flue gas generated by the main engine (such as a marine diesel engine) can be fully utilized, and the defects in the known waste heat recovery system are overcome. The first mixed working medium can be used as a circulating working medium, the energy carried by the flue gas is fully recovered, the recovered heat energy is converted into electric energy, and meanwhile, the waste heat recovery power generation system further comprises a refrigeration system which can utilize low-temperature waste heat which cannot be converted into electric energy for refrigeration, so that the utilization rate of the heat energy is further improved.
In this summary, concepts in a simplified form are introduced that are further described in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Drawings
The following drawings of the invention are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings, there is shown in the drawings,
fig. 1 is a schematic structural diagram of a waste heat recovery power generation system according to an embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.
Fig. 1 is a schematic structural diagram of a waste heat recovery power generation system according to an embodiment of the present invention. As shown in fig. 1, the system includes: the system comprises a main machine 10, a first heat exchange device 21, a gas-liquid separation device 31, an expander generator set 40, a mixing device 51 and a refrigeration system 60.
Specifically, in this embodiment, the main machine 10 may be a power output unit such as a diesel engine for a ship. The main body 10 is capable of generating smoke. The flue gas can be medium-high temperature flue gas. The first heat exchange device 21 is communicated with the main machine 10 and is used for exchanging heat between the first mixed working medium and the flue gas so as to heat the first mixed working medium. Specifically, the first heat exchange device 21 is communicated with an exhaust passage of the main unit 10, so that the flue gas exhausted from the main unit 10 can enter the first heat exchange device 21. The first heat exchanger 21 can then heat the first mixed working medium by means of the flue gas having a medium-high temperature. For example, the first heat exchange device 21 may be an industrial heat exchanger. The first heat exchange means 21 may comprise a hot side and a cold side. The cold side and the hot side may be pipes intertwined and in thermal contact. The hot side is used for circulating the flue gas, and the cold side is used for circulating first mixed working medium for the hot side can carry out the heat transfer to the cold side, and then heats the first mixed working medium of cold side. The first heat exchanger 21, the second heat exchanger 22 and the third heat exchanger 23, which will be described later, may be all industrial heat exchanger structures in the prior art, and will not be described herein again.
The first mixed working medium is a mixture at least comprising two working media, wherein the boiling point of at least one working medium is lower than 100 ℃. For example, the first mixed working medium may be an ammonia water mixture, wherein the boiling point of ammonia gas is lower than 100 ℃, so that ammonia gas is easy to evaporate to form ammonia vapor after the ammonia water mixture is heated, and the remaining part is water containing a small amount of ammonia gas. Preferably, the ammonia is a standard conventional chemical solvent, is widely applied to agriculture, refrigeration, power industry and the like, is properly treated, is a safe chemical preparation conforming to ecology, and the price of the ammonia water working medium is much lower than that of the organic working medium. Compared with the prior art in which water is used as a working medium, the steam for power generation can be generated under the condition of low temperature of flue gas, and the utilization rate of heat is further improved.
In addition, compared with water and organic working media, the ammonia water is subjected to variable-temperature evaporation in the evaporation process, so that the irreversible loss of the working media in the heat absorption process can be reduced, a good matching characteristic is formed with the temperature of a heat source, and the utilization rate of the heat source is improved. The first mixed working medium is heated to form a second mixed working medium and first steam (such as ammonia steam). The critical pressure of ammonia is 12MPa, the working pressure of the pressure bearing part can be reduced at a higher heat absorption temperature by taking ammonia water as a working medium, the design and the operation of saturated heat exchange equipment and a pipeline system of a waste heat recovery power generation system are facilitated, and the equipment investment is reduced.
It should be noted that the second mixed working medium contains different ammonia gas contents in different processes, but the second mixed working medium is called the second mixed working medium with a lower ammonia gas content. Therefore, in the following description, the first mixed working medium is ammonia water (ammonia-rich solution) with a relatively high ammonia content; the second mixed working medium is also ammonia water mixture (ammonia-poor solution) with less ammonia content, and the first steam is the main part of ammonia gas and the rest part of steam.
Of course, according to the inventive concept of the present invention, the first mixed working fluid may include at least one of refrigerants R401A, R402B, R405A, R407C, R409A. The requirements of the application are met as long as the boiling point of at least one working medium is lower than 100 ℃, namely lower than the boiling point of water.
The first mixed working medium is ammonia water (ammonia-rich solution) with high ammonia content; the second mixed working medium is also an ammonia water mixture (ammonia-poor solution) with less ammonia content, and the first steam is a main part of ammonia gas and the rest part of steam for illustration.
The first mixed working medium can generate a second mixed working medium and first steam after being heated. Specifically, in this embodiment, the ammonia water is heated to generate ammonia vapor and an ammonia water mixture containing a small amount of ammonia gas. The mixture is introduced into the gas-liquid separation device 31 connected to the first heat exchange device 21 through a pipe. After the mixture is introduced into the gas-liquid separation device 31, the first steam (e.g., ammonia steam) is introduced into the expander generator unit 40 connected thereto through, for example, a pipe provided at an upper portion of the gas-liquid separation device 31, and the expander generator unit 40 can generate power by using the ammonia steam. The ammonia water mixture (second mixed working fluid) containing a small amount of ammonia gas in the gas-liquid separation device 31 may flow out through a pipe provided at, for example, a lower portion of the gas-liquid separation device 31.
The first steam with high temperature and high pressure is changed into the first steam with low pressure and low temperature after acting in the expander generator set 40, and then is discharged from the outlet of the expander generator set 40. The mixing device 51 may be respectively communicated with the second mixed working medium outlet of the gas-liquid separation device 31 and the outlet of the expander generator set 40, for mixing the second mixed working medium and the first steam with reduced temperature. The first steam may be mixed with water containing a small amount of ammonia gas in the mixing device 51, thereby forming a gas-liquid mixture.
Specifically, the expander generator set 40 may be a high inlet pressure turbine, and may take the form of a centripetal turbine, a centrifugal turbine, a screw expander, or the like. The generator can select a high-speed generator or a low-speed generator according to the power grade and the rotating speed condition. If a high speed generator is used, the expander is directly coaxial with the generator or coupled via a coupling. If a low speed generator is used, a reduction gearbox may be used to connect the expander to the generator.
In the embodiment, in order to utilize the heat of the flue gas more efficiently, reduce the irreversible loss in the heat release process to the maximum extent and improve the heat energy utilization efficiency, the system further comprises a second heat exchange device 22. Specifically, the hot side of the second heat exchange device 22 is located between the mixing device 51 and the refrigeration system 60, wherein the refrigeration system 60 is communicated with the mixing device 51, and is used for condensing a gas-liquid mixture (i.e., a gas-liquid mixture of the second mixed working medium and the first steam) generated after mixing in the mixing device 51. The cold side of the second heat exchange device 22 is located between the first heat exchange device 21 and the refrigeration system 60. The second heat exchange device 22 heats the condensed first mixed working medium of the refrigeration system 60 by using the heat of the second mixed working medium (ammonia water mixture containing a small amount of ammonia gas) coming out of the gas-liquid separation device 31. And further ensure that the first mixed working medium can rise to a proper temperature before entering the first heat exchange device 21, and further ensure that the first mixed working medium can better exchange heat in the first heat exchange device 21.
Further, the system may further comprise a third heat exchange device 23. The hot side of the third heat exchange means 23 may be located between the gas-liquid separation device 31 and the mixing means 51. The cold side of the third heat exchange means 23 may be located between the cold side of the second heat exchange means 22 and the first heat exchange means 21. The third heat exchange device 23 heats the condensed first mixed working medium by using the heat of the gas-liquid mixture of the first steam and the second mixed working medium just coming out of the mixing device 51, so that the gas-liquid mixture of the first steam and the second mixed working medium can be reduced to a relatively low temperature before entering the refrigeration system 60, the condensation power consumption of the refrigeration system 60 is lower, the heat can be fully utilized in a stepped manner, and the utilization rate of the heat is further improved.
The refrigeration system 60 may be in communication with the mixing device 51, and is configured to condense the mixed gas-liquid mixture (an ammonia water mixture containing a small amount of ammonia gas and ammonia vapor) into a first mixed working medium. Specifically, the refrigeration system 60 includes a first condenser 61, a second condenser 62, an evaporator 63, an absorber 64, and a fourth heat exchange device 65, which are connected in series. Specifically, the first condenser 61 includes two inlets and three outlets, one inlet is connected to the hot side outlet of the second heat exchanging device 22 in the power generating system, the other inlet is connected to the cold side outlet of the fourth heat exchanging device 65 of the refrigerating system 60, one outlet is connected to the inlet of the pump body 90 close to the second heat exchanging device in the power generating system, one outlet is connected to the hot side inlet of the fourth heat exchanging device 65 of the refrigerating system 60, and the other outlet is connected to the second condenser 62 of the refrigerating system 60.
The hot side of the first condenser 61 is a gas-liquid mixture (a gas-liquid mixture of the mixed second mixed working medium and the first steam) to be condensed into a first mixed working medium, and the cold side of the first condenser 61 is a third mixed working medium of the refrigeration system 60, wherein the third mixed working medium is a refrigeration working medium, and the following description is given by using the refrigeration working medium. Preferably, the refrigeration working medium can be an ammonia water working medium. The gas-liquid mixture in the first condenser 61 also has a certain amount of heat, so that the ammonia water working medium can exchange heat with the gas-liquid mixture, so that the ammonia water working medium is heated by the heat source (gas-liquid mixture) in the first condenser 61.
After being heated, the ammonia water working medium of the refrigeration system 60 separates a certain amount of ammonia-rich steam (namely, second steam) and carries out gas-liquid separation in the first condenser 61. The separated ammonia-rich steam enters a second condenser 62 connected with the first condenser 61 through a pipeline, and the non-evaporated ammonia water solution becomes a poor ammonia solution (namely, a fourth mixed working medium) and enters a fourth heat exchange device 65 connected with the first condenser 61.
The refrigeration working medium in the refrigeration system 60 can be ammonia water as the refrigeration working medium, a gas-liquid mixture is used as a heat source of the refrigeration system 60, the heat which needs to be discharged in the power generation system is further recovered by utilizing the characteristic of low evaporation temperature of the ammonia water, and the low-temperature heat is converted into cold water at the temperature of minus 60-10 ℃, so that the heat utilization rate of the power generation system is improved. Alternatively, the refrigerant in the refrigeration system 60 may also be water-lithium chloride (LiCl-H2O), water-lithium iodide (LiI-H2O), water-lithium bromide (LiBr-H2O), ammonia-lithium nitrate (NH3-LiNO3), ammonia-sodium thiocyanate (NH3-NaSCN), or other non-azeotropic mixtures, which may be selected according to actual needs. It can be understood that, when the second steam is water-lithium chloride (LiCl-H2O), the fourth mixed working medium is an aqueous solution containing a small amount of lithium chloride, and the second steam is steam rich in lithium chloride.
In the second condenser 62 of the refrigeration system 60, the hot side is rich ammonia vapor (i.e., the second vapor), and the cold side is low-temperature return water (cold water). The ammonia-rich steam is condensed in the condenser to release heat so as to heat the low-temperature backwater, and the ammonia-rich steam is condensed into high-pressure low-temperature ammonia-rich solution.
The inlet of the first throttle valve 66 is connected to the hot side outlet of the second condenser 62, and the outlet is connected to the inlet of the evaporator 63, so that the ammonia-rich solution condensed from the ammonia-rich vapor (i.e., the second vapor) flows out of the second condenser 62 and enters the evaporator 63 through the first throttle valve 66. Specifically, the first throttle valve 66 of the refrigeration system 60 is used for depressurizing the condensed high-pressure low-temperature ammonia-rich solution into a low-pressure low-temperature ammonia-rich solution, so as to evaporate the condensed high-pressure low-temperature ammonia-rich solution in the evaporator 63 at a lower temperature. The low-pressure low-temperature ammonia-rich solution is evaporated in the evaporator 63 and absorbs heat of the cold water working medium to become low-pressure ammonia-rich steam, the cold water working medium further releases heat and is cooled to be a lower-temperature cold water working medium (cold water), the cold water working medium is produced, and the cold water working medium can be used for refrigeration.
The absorber 64 in the refrigeration system 60 absorbs the low-pressure ammonia-rich vapor (i.e., the second vapor) from the evaporator 63 by using the lean ammonia solution (i.e., the fourth mixed working medium) from the first condenser 61 under the low-pressure condition, and generates an ammonia water working medium after the absorption process, thereby realizing the circulation of the refrigeration working medium.
Specifically, the absorber 64 may have three inlets and two outlets, the three inlets are respectively connected to the cold-side outlet of the evaporator 63, the outlet of the second throttle valve 67, and the low-temperature return water inlet, one of the two outlets is a low-temperature return water heat absorption discharge outlet, and the other outlet is connected to an inlet of the pump body 90, wherein the pump body 90 is used for performing pressurization adjustment on the basic ammonia water solution of the absorber 64, the inlet of the pump body 90 is connected to the outlet of the absorber 64, and the outlet is connected to the cold-side inlet of the heat exchanger. The absorber 64 absorbs the heat released in the process of absorbing the low-pressure ammonia-rich steam (i.e., the second steam) by the low-temperature backwater (cold water) to further promote the output of the ammonia water working medium.
The inlet and outlet of the hot side of the fourth heat exchange device 65 are respectively connected with the outlet of the first condenser 61 and the inlet of the second throttle valve 67, and the inlet and outlet of the cold side of the fourth heat exchange device are respectively connected with the outlet of the pump body 90 and the inlet of the first condenser 61. The fourth heat exchanging device 65 in the refrigeration system 60 mainly functions to recover the heat energy of the high-temperature ammonia-poor solution (i.e., the fourth mixed working medium) generated by the first condenser 61, thereby improving the overall utilization rate of the heat energy of the system.
The refrigeration system 60 condenses the gas-liquid mixture to form a first mixed working medium (ammonia water), and the first mixed working medium can be conveyed into the first heat exchange device 21 through the pump body 90 arranged between the refrigeration system 60 and the first heat exchange device 21, so that a complete heat exchange cycle is formed.
In the present embodiment, a pressure regulating valve 72 may be further provided between the gas-liquid separation device 31 and the mixing device 51. The pressure regulating valve 72 may be two-stage. The pressure regulating valve 72 can control the amount of the second mixed working medium in the gas-liquid separation device 31 entering the mixing device 51, and further regulate the concentration of the mixture in the mixing device 51. For example, when a large amount of the second mixed working medium is fed into the mixing device 51, the ammonia concentration in the ammonia water decreases. The waste heat recovery system will also operate off-design when the host 10 is operated at different loads in view of sea state changes. At the moment, the operating system can be optimized by adjusting the mixing proportion (concentration) of the ammonia water in the operating system, changing the characteristics of the evaporation temperature and the like of the ammonia water, so that the heat release process of the heat source can be better matched with the heat absorption process curve of the ammonia water, the irreversible loss in the heat release process is reduced to the maximum extent, and the heat energy utilization efficiency is improved.
In this implementation, the system further includes a frequency conversion device 80. The variable frequency device 80 may be electrically connected to the expander generator set 40. The system mainly comprises a rectifying unit (alternating current to direct current), a filtering unit, an inverting unit (direct current to alternating current), a braking unit, a driving unit, a detection unit micro-processing unit and the like. The frequency converter adjusts the power frequency, so that the generated electric energy meets the requirements of a ship power grid, and in addition, the frequency converter can also have a plurality of protection functions, such as overcurrent, overvoltage, overload protection and the like.
The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustrative and descriptive purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (11)

1. A heat recovery power generation system, comprising:
a main machine, which generates flue gas;
the first heat exchange device is communicated with the main machine and is used for exchanging heat between a first mixed working medium and the flue gas so as to heat the first mixed working medium to generate first steam;
the gas-liquid separation device is communicated with the first heat exchange device and is used for separating a second mixed working medium generated by heating the first mixed working medium from the first steam;
the expander generator set is communicated with the first steam outlet of the gas-liquid separation device and is used for generating power by utilizing the first steam;
The mixing device is respectively communicated with a second mixed working medium outlet of the gas-liquid separation device and an outlet of the expander generator set and is used for mixing the second mixed working medium and the first steam with the reduced temperature into a gas-liquid mixture;
the refrigerating system is communicated with the mixing device and is used for condensing the gas-liquid mixture so as to liquefy the gas-liquid mixture into the first mixed working medium;
the first mixed working medium is a mixture at least comprising two working media, wherein the boiling point of at least one of the working media is lower than 100 ℃.
2. The waste heat recovery power generation system according to claim 1, wherein the second mixed working medium is a mixture of the first mixed working medium and the working medium with the lowest boiling point, and the second mixed working medium is partially evaporated into the first steam, and the first steam is formed by evaporation of the first mixed working medium and the working medium with the lowest boiling point.
3. The heat recovery power generation system of claim 1, wherein the first mixed working medium is ammonia water.
4. The heat recovery power generation system of claim 1, wherein the first mixed working fluid comprises at least one of refrigerants R401A, R402B, R405A, R407C and R409A.
5. The heat recovery power generation system of claim 1, further comprising a second heat exchange device, a hot side of the second heat exchange device being located between the mixing device and the refrigeration system, and a cold side of the second heat exchange device being located between the first heat exchange device and the refrigeration system.
6. The heat recovery power generation system of claim 5, further comprising a third heat exchange device, a hot side of the third heat exchange device being located between the gas-liquid separation device and the mixing device, and a cold side of the third heat exchange device being located between the cold side of the second heat exchange device and the first heat exchange device.
7. The heat recovery power generation system of claim 6, wherein a pressure regulating valve is disposed between the hot side of the third heat exchange device and the mixing device, and is configured to control the flow rate of the second mixed working medium input into the mixing device.
8. The heat recovery power generation system of claim 1, further comprising a frequency conversion device connected to the expander generator set for controlling the expander generator set.
9. The heat recovery power generation system of claim 5, wherein the refrigeration system comprises:
the heat exchanger comprises a first heat exchange device, a second heat exchange device, a first condenser, a second condenser and a second heat exchange device, wherein the first condenser is connected with the second heat exchange device, the hot side of the first condenser is communicated with the hot side of the second heat exchange device and is used for allowing the gas-liquid mixture passing through the second heat exchange device to flow through, a third mixed working medium flows through the cold side of the first condenser, the first condenser is used for performing heat exchange on the third mixed working medium and the gas-liquid mixture, and the third mixed working medium is heated to form high-pressure low-temperature second steam and a fourth mixed working medium;
the second condenser is connected with the first condenser, low-temperature return water flows through the cold side of the second condenser, the hot side of the second condenser is communicated with the cold side of the first condenser, high-pressure low-temperature second steam flows through the hot side of the second condenser, and the second steam and the low-temperature return water exchange heat to be condensed into a fourth mixed working medium with high pressure and low temperature;
the first throttling valve is connected with the condenser and used for depressurizing the fourth mixed working medium with high pressure and low temperature into the fourth mixed working medium with low pressure and low temperature;
The evaporator is connected with the first throttling valve and used for receiving the low-pressure and low-temperature fourth mixed working medium input by the first throttling valve, the fourth mixed working medium is evaporated in the evaporator and absorbs the heat of a cold water working medium in the evaporator so as to change the heat into second steam, and the cold water working medium further releases heat and is cooled into a lower-temperature cold water working medium;
the absorber is respectively connected with the first condenser and the evaporator, and the absorber is used for mixing the second steam and the fourth mixed working medium to form the third mixed working medium.
10. The heat recovery power generation system of claim 9, wherein the refrigeration system further comprises:
and the inlet of the hot side of the fourth heat exchange device is connected with the first condenser, the outlet of the hot side of the fourth heat exchange device is connected with the absorber, the inlet of the cold side of the fourth heat exchange device is connected with the absorber, the outlet of the cold side of the fourth heat exchange device is connected with the first condenser, and the fourth heat exchange device is used for carrying out heat exchange on the fourth mixed working medium from the first condenser and the third mixed working medium from the absorber.
11. The heat recovery power generation system of claim 9, wherein the third mixed working fluid in the refrigeration system comprises at least one non-azeotropic mixture of ammonia water, water-lithium chloride, water-lithium iodide, water-lithium bromide, ammonia-lithium nitrate, and ammonia-sodium thiocyanate.
CN201910365176.XA 2019-04-30 2019-04-30 Waste heat recovery power generation system Pending CN111852684A (en)

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