CN116294291A - Coupling system of natural gas differential pressure power generation and air source heat pump - Google Patents
Coupling system of natural gas differential pressure power generation and air source heat pump Download PDFInfo
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- CN116294291A CN116294291A CN202310038598.2A CN202310038598A CN116294291A CN 116294291 A CN116294291 A CN 116294291A CN 202310038598 A CN202310038598 A CN 202310038598A CN 116294291 A CN116294291 A CN 116294291A
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 298
- 239000003345 natural gas Substances 0.000 title claims abstract description 148
- 238000010248 power generation Methods 0.000 title claims abstract description 64
- 230000008878 coupling Effects 0.000 title claims abstract description 31
- 238000010168 coupling process Methods 0.000 title claims abstract description 31
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 31
- 239000007789 gas Substances 0.000 claims abstract description 24
- 238000003303 reheating Methods 0.000 claims abstract description 14
- 238000010257 thawing Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000003638 chemical reducing agent Substances 0.000 claims description 10
- 238000001704 evaporation Methods 0.000 claims description 9
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- 238000002347 injection Methods 0.000 claims description 6
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- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 4
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- 238000005265 energy consumption Methods 0.000 abstract 1
- 239000003507 refrigerant Substances 0.000 description 15
- 238000010586 diagram Methods 0.000 description 7
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- 238000012423 maintenance Methods 0.000 description 3
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- 231100000252 nontoxic Toxicity 0.000 description 2
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- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- 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
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H4/00—Fluid heaters characterised by the use of heat pumps
- F24H4/06—Air heaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B30/00—Heat pumps
- F25B30/06—Heat pumps characterised by the source of low potential heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
- F25B41/24—Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part
-
- 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
- F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
- F25B47/02—Defrosting cycles
- F25B47/022—Defrosting cycles hot gas defrosting
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
The invention relates to a coupling system of natural gas pressure difference power generation and an air source heat pump, which comprises a natural gas pressure difference power generation subsystem and an air source heat pump subsystem, wherein the air source heat pump subsystem is driven by electric quantity generated by the natural gas pressure difference power generation subsystem, and heat generated by the air source heat pump subsystem is utilized to heat incoming natural gas, so that the enthalpy value of the incoming natural gas is improved, and the generated energy of the natural gas pressure difference power generation subsystem is increased; and a part of compressor exhaust gas is led out from the air source heat pump subsystem and used for reheating the expanded low-temperature natural gas, so that the temperature of the low-temperature natural gas meets the requirement of being sent into a downstream pipe network. Compared with the prior art, the invention can effectively solve the problems of surplus cold energy and high heating energy consumption of low-temperature natural gas caused by the lack of a heat source and the effective utilization of cold energy of the existing natural valve station, and greatly improves the energy utilization rate of the system.
Description
Technical Field
The invention relates to the field of differential pressure power generation and air source heat pumps of natural valve stations, in particular to a coupling system of natural gas differential pressure power generation and air source heat pumps.
Background
In general, natural gas supply pressure of a natural valve station is high, and design pressure of a downstream pipe network is low, and pressure difference between a high-pressure gas line and the downstream pipe network is large, so that pressure reduction is required to meet the demand of the downstream pipe network. If the pressure regulating valve is directly adopted for reducing the pressure, a large amount of mechanical energy is wasted, the temperature of the natural gas after the pressure reduction is lower, the requirement of the gas supply temperature higher than 5 ℃ cannot be met, and if the natural gas directly enters the expansion machine for expansion, the temperature of the gas exhaust is also lower, and available cold energy exists. However, in the existing natural gas valve stations of all levels, the technology of waste heat resource heat supply and cold energy utilization is often lacking, and cold energy of low-temperature natural gas becomes a burden instead. In order to ensure that the temperature of the generated natural gas is enough to enter a lower pipe network, the traditional method utilizes the heat generated by burning the natural gas to rewarming the natural gas, which is not only low in efficiency, but also consumes a large amount of fuel gas.
Patent number CN 103334891A discloses a differential pressure power generation device and technology, and the invention adopts an expander to recycle mechanical power generated in the depressurization process of natural gas for power generation. However, the natural gas is not preheated, and the natural gas before expansion and the natural gas after expansion are subjected to heat exchange, so that the enthalpy value of the natural gas before expansion is reduced, the generated energy is reduced, and the influence of lower temperature of the natural gas after direct expansion on equipment is not considered.
Patent number CN 114876586A discloses a differential pressure power generation device and technology, and the invention proposes to heat high-pressure natural gas by using a heater, but does not propose a specific implementation method. The invention proposes to reheat the expanded low temperature natural gas using a water bath vaporizer, but the process consumes a significant amount of natural gas and electrical energy.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a coupling system of natural gas pressure difference power generation and an air source heat pump, which solves the problems that the natural gas pressure in a gate valve station is too high to directly enter a downstream pipe network and the cold energy of low-temperature natural gas after direct pressure regulation or expansion is not utilized.
The aim of the invention can be achieved by the following technical scheme: the coupling system of the natural gas pressure difference power generation and the air source heat pump comprises a natural gas pressure difference power generation subsystem and an air source heat pump subsystem, and is characterized in that the air source heat pump subsystem is driven by electric quantity generated by the natural gas pressure difference power generation subsystem, and heat generated by the air source heat pump subsystem is utilized to heat incoming natural gas, so that the enthalpy value of the incoming natural gas is improved, and the power generation capacity of the natural gas pressure difference power generation subsystem is increased; and a part of compressor exhaust gas is led out from the air source heat pump subsystem and used for reheating the expanded low-temperature natural gas, so that the temperature of the low-temperature natural gas meets the requirement of being sent into a downstream pipe network.
Further, the natural gas differential pressure power generation subsystem comprises a natural gas main path and a power generation branch path;
the natural gas main path comprises a main path flow control valve, a condenser, a main path first check valve, an expander, a main path ball valve, a motor, a main path second check valve, a reheating device, a main path third check valve and an outlet ball valve which are connected in sequence; the bypass ball valve, the first heat exchanger and the bypass first ball check valve are sequentially arranged on the branch pipeline; the bypass first ball check valve is sequentially connected with the reheater and the main third check valve, is provided with a second ball check valve connected in parallel at one side of the connecting pipeline, and is then connected with the outlet ball valve;
the power generation branch circuit comprises an expander, a speed reducer, a generator and a motor which are sequentially connected with the main flow path, wherein the generator is connected with the storage battery.
Furthermore, the natural gas differential pressure power generation subsystem further comprises a natural gas bypass, wherein the natural gas bypass is connected in parallel with two ends of the main flow control valve and the main first check valve, and comprises a bypass flow control valve, an auxiliary heater and a bypass first check valve which are sequentially connected.
The natural gas flow entering the condenser or the auxiliary heater is regulated by the main flow control valve and the bypass flow control valve, so that the temperature of the natural gas flow is increased, the enthalpy value of the natural gas flow is increased, then the natural gas flow is introduced into the expander to do expansion work, the output shaft is driven by the speed reducer to drive the generator to generate power, one part of electric quantity is stored in the storage battery, and the other part of electric quantity is used for meeting the requirement that the motor drives the air source heat pump subsystem;
the low-temperature natural gas expanded by the expander enters two branches: one is to enter the motor to cool the motor, then the motor is reheated by the reheater and then flows into a downstream pipe network through the outlet ball valve, and the other is to enter the first heat exchanger to utilize cold energy, and then natural gas which is bypassed through the first ball check valve and comes out of the cooling motor is converged to enter the reheater.
Preferably, the reheater, the first heat exchanger, the auxiliary heater and the condenser are shell-and-tube, tube-fin or high-efficiency plate heat exchangers.
Preferably, the heat source of the auxiliary heater is hot water heated by natural gas combustion.
Preferably, the storage battery is an industrial lead-acid storage battery, a nickel-cadmium storage battery or a nickel-zinc storage battery.
Further, the air source heat pump subsystem comprises a heat pump main circuit, an air injection enthalpy-increasing branch circuit and exhaust reheating;
the main path of the heat pump comprises a compressor, a main path first butterfly valve, a condenser, a second heat exchanger, a main path throttle valve, a main path first check valve, an evaporator and a main path second butterfly valve which are sequentially connected, and the main path second butterfly valve is connected with the compressor in a return way;
the condenser and the second heat exchanger are connected in parallel with a branch pipeline, a throttle valve is arranged on the branch pipeline, and the compressor, the first butterfly valve of the main pipeline, the condenser, the throttle valve and the second heat exchanger are sequentially connected to form an enhanced vapor injection branch;
a circulation loop is arranged between the compressor and the reheater, and a bypass flow control valve and a bypass first check valve are arranged on the circulation loop; the compressor, the bypass flow control valve, the reheater and the bypass first check valve are sequentially connected to form an exhaust reheating branch;
still further, the air source heat pump subsystem also includes the hot gas defrosting branch road, the hot gas defrosting branch road includes compressor, bypass first butterfly valve, bypass second check valve, evaporimeter, constant pressure valve and bypass second butterfly valve that connect gradually.
The reheating device, the second heat exchanger and the evaporator are shell-and-tube, tube-fin or high-efficiency plate heat exchangers.
The heat source of the evaporator is from air or other low temperature heat sources of the valve station, and the evaporating temperature of the evaporator can be changed along with the temperature of the heat source.
Preferably, the refrigerant working medium is a nontoxic and nonflammable safe working medium.
Preferably, the refrigerant working medium is an environment-friendly working medium with ODP of 0 and low GWP.
Preferably, the refrigerant is R134a, R410a or R1234yf.
Preferably, the butterfly valve in the air source heat pump subsystem is a fluorine-lined butterfly valve or a turbine full-fluorine-lined butterfly valve. The check valve is a stainless steel swing check valve. The ball valve is a fixed shaft type ball valve.
Preferably, the heat source of the evaporator is air. The heat source of the auxiliary heater is hot water heated by natural gas combustion.
Compared with the prior art, the invention has the following effects:
1. the invention provides a coupling system of natural gas differential pressure power generation and an air source heat pump, which adopts a condenser in the air source heat pump as a preheater of a natural gas differential pressure power generation subsystem, preheats high-pressure natural gas, then enters an expander, and is connected with an auxiliary heater in parallel, so that the temperature of the natural gas before expansion is increased, the temperature can be controlled to reach a set temperature, the generating capacity of the differential pressure power generation system is increased, the temperature of the natural gas after expansion is controlled within a gas supply temperature range, the electric quantity of a driving air source heat pump subsystem is derived from the differential pressure power generation system, the complementation of heat energy and electric energy is realized, the heat pump circulation is driven by consuming part of the generating capacity of the natural gas, the flowing natural gas is heated, the expanded natural gas meets the requirement of the gas supply temperature, and finally is sent into a downstream pipe network, and the generating capacity of the expander can be greatly increased. Compared with the traditional methods of natural gas water bath heating, electric heating and the like, the system has high efficiency, low cost and more energy conservation.
2. The invention provides a coupling system of natural gas differential pressure power generation and an air source heat pump, which is characterized in that an air supplementing enthalpy increasing branch is added in an air source heat pump subsystem in order to improve the COP of the heat pump; considering the problem of frosting caused by too low evaporation temperature (especially in winter), a hot gas defrosting branch is added in the air source heat pump subsystem; the temperature of the expanded natural gas after cold energy utilization still cannot meet the requirement of the air supply temperature, and a hot gas reheating branch is added.
3. The coupling system of the natural gas differential pressure power generation and the air source heat pump provided by the invention has the advantages that the problems of defrosting, maintenance and cleaning of the natural gas heat pump system are considered, and the bypass for heating the natural gas by using the auxiliary heater is increased. The flow control valve can realize the operation mode of independent heating or common heating of the main path and the bypass.
Drawings
FIG. 1 is a schematic diagram of a coupling system of natural gas differential pressure power generation and an air source heat pump of the present invention;
FIG. 2 is a schematic diagram of a normal mode of operation of the coupling system of the natural gas differential pressure power generation and air source heat pump of the present invention;
FIG. 3 is a schematic diagram of an auxiliary mode of operation of the coupling system of the natural gas differential pressure power generation and air source heat pump of the present invention;
FIG. 4 is a schematic diagram of a common heating mode of operation of the coupling system of the natural gas differential pressure power generation and air source heat pump of the present invention;
FIG. 5 is a schematic diagram of a defrost mode of the coupling system operation of the natural gas differential pressure power generation and air source heat pump of the present invention;
wherein, the main equipment is: 101-expansion machine, 102-speed reducer, 103-generator, 104-storage battery, 105-motor, 106-reheater, 107-outlet ball valve, 108-first heat exchanger, 109-auxiliary heater, 201-compressor, 202-condenser, 203-second heat exchanger, 204-main throttle valve, 205-evaporator, 206-bypass throttle valve, 207-constant pressure valve;
the main valve is as follows: 111-main flow control valve, 112-main first check valve, 113-main ball valve, 114-main second check valve, 115-main third check valve, 121-bypass flow control valve, 122-bypass first check valve, 123-bypass ball valve, 124-bypass first ball check valve, 125-bypass second ball check valve, 211-main first butterfly valve, 212-main check valve, 213-main second butterfly valve, 221-bypass flow control valve, 222-bypass first check valve, 231-bypass first butterfly valve, 232-bypass second check valve, 233-bypass second butterfly valve.
Detailed Description
The following examples or drawings are provided to illustrate the invention in further detail and are not intended to limit the scope of the invention.
The invention provides a coupling system of natural gas pressure difference power generation and an air source heat pump. And a part of electric quantity generated by the natural gas differential pressure power generation subsystem is used for driving the air source heat pump subsystem, and heat generated by a condenser in the heat pump system is utilized for heating incoming natural gas, so that the enthalpy value of the incoming natural gas is improved, and the generated energy of the differential pressure power generation system is increased. And a part of compressor exhaust gas is led out from the air source heat pump subsystem and used for reheating the expanded low-temperature natural gas, so that the temperature of the low-temperature natural gas meets the requirement of being sent into a downstream pipe network.
As shown in fig. 1, the coupling system of the natural gas differential pressure power generation and the air source heat pump comprises an expander 101, a speed reducer 102, a generator 103, a storage battery 104, a motor 105, a reheater 106, an outlet ball valve 107, a first heat exchanger 108, an auxiliary heater 109, a compressor 201, a condenser 202, a second heat exchanger 203, a main path throttle valve 204, an evaporator 205 and a bypass throttle valve 206. The main flow control valve 111, the main first check valve 112, the main ball valve 113, the main second check valve 114, the main third check valve 115, the bypass flow control valve 121, the bypass first check valve 122, the bypass ball valve 123, the bypass first ball check valve 124, the bypass second ball check valve 125, the main first butterfly valve 211, the main check valve 212, the main second butterfly valve 213, the bypass flow control valve 221, the bypass first check valve 222, the bypass first butterfly valve 231, the bypass second check valve 232, and the bypass second butterfly valve 233.
In a natural gas pressure differential power generation subsystem:
the main flow control valve 111, the condenser 202, the main first check valve 112, the expander 101, the main ball valve 113, the motor 105, the main second check valve 114, the reheater 106, the main third check valve 115 and the outlet ball valve 107 are sequentially connected to form a main flow path;
the expander 101, the speed reducer 102, the generator 103 and the motor 105 are sequentially connected to form a power generation branch, wherein the generator 103 is connected with the storage battery 104;
the bypass flow control valve 121, the auxiliary heater 109, and the bypass first check valve 122 are connected in sequence to form an auxiliary flow path, and the auxiliary flow path is connected in parallel with the main flow control valve 111, the condenser 202, and the main first check valve 112;
the bypass ball valve 123, the first heat exchanger 108 and the bypass first ball check valve 124 are sequentially connected to form a heat exchange branch, and the heat exchange branch is connected in parallel with the main ball valve 113, the motor 105 and the main second check valve 114;
the bypass second ball check valve 125 is connected in parallel with the bypass first ball check valve 124, the reheater 106, and the main third check valve 115. I.e. the first heat exchanger 108 is connected to the outlet ball valve 107 by two parallel paths, one of which is a bypass first ball check valve 124, a reheater 106 and a main third check valve 115, which are connected in sequence, and the other of which is provided with a bypass second ball check valve 125.
In the air source heat pump subsystem: the system comprises a heat pump main circuit, an enthalpy-increasing jet branch circuit, an exhaust reheating and hot gas defrosting branch circuit;
the main circuit of the heat pump comprises a compressor 201, a main circuit first butterfly valve 211, a condenser 202, a second heat exchanger 203, a main circuit throttle valve 204, a main circuit first check valve 212, an evaporator 205 and a main circuit second butterfly valve 213 which are sequentially connected, wherein the main circuit second butterfly valve 213 is connected with the compressor 201 in a return way;
the condenser 202 and the second heat exchanger 203 are connected in parallel with a branch pipeline, a throttle valve 206 is arranged on the branch pipeline, and the compressor 201, the main first butterfly valve 211, the condenser 202, the throttle valve 206 and the second heat exchanger 203 are sequentially connected to form an enhanced vapor injection branch;
a circulation loop is arranged between the compressor 201 and the reheater 106, and a bypass flow control valve 221 and a bypass first check valve 222 are arranged on the circulation loop; the compressor 201, the bypass flow control valve 221, the reheater 106 and the bypass first check valve 222 are sequentially connected to form an exhaust reheating branch;
another circulation loop is arranged between the compressor 201 and the evaporator 205, and comprises a compressor 201, a bypass first butterfly valve 231, a bypass second check valve 232, the evaporator 205, a constant pressure valve 207 and a bypass second butterfly valve 223 which are sequentially connected to form a hot gas defrosting branch;
the heat pump main circuit, the vapor injection enthalpy-increasing branch circuit, the exhaust reheating and hot gas defrosting branch circuit form a complete air source heat pump cycle.
In a natural gas pressure differential power generation subsystem:
the main flow control valve 111 is opened, the bypass flow control valve 121 is closed, natural gas enters the heating main path, is heated in the condenser 202, then enters the expander 101 to expand, drives the output shaft to drive the generator 103 to generate electricity through the speed reducer 102, and is stored in the storage battery 104.
The expanded natural gas is divided into two paths: one path enters a motor 105 to cool the motor, then enters a reheater 106 to reheat, and finally flows out of a downstream pipe network through an outlet ball valve 107; the other path enters the first heat exchanger 108, the cold energy of the low-temperature natural gas is applied to ice making, a water chilling unit or dry ice making, additional benefits are generated, and then the natural gas is converged with the natural gas at the outlet of a cooling pipeline of the motor 105 through the bypass first ball check valve 124, and enters the reheater 106.
In the air-source heat pump subsystem, a portion of the charge in battery 104 is now used in compressor 201 to drive the air-source heat pump subsystem, and the refrigerant absorbs heat from the air or other heat source in evaporator 205 to evaporate and then enters compressor 201 to be compressed into a high temperature gas at a condensing pressure.
The refrigerant is divided into two paths: in the main path, the refrigerant enters the condenser 202 to condense Cheng Gaowen liquid and release heat, then a part of high-temperature liquid enters the second heat exchanger 203 to be supercooled, and enters the evaporator 205 to be evaporated after being reduced to the evaporation pressure by the main path throttle valve 204 and returns to the first air suction port of the compressor 201 to complete circulation; the other part of the high-temperature liquid is depressurized to the intermediate pressure by the bypass throttle valve 206, enters the second heat exchanger 203 to absorb heat and evaporate, returns to the second air suction port of the compressor 201, is mixed with the steam of the first air suction port, and participates in the next compression process. By-pass, the high temperature compressor discharge gas enters the reheater 106 through the by-pass flow control valve 221 to heat the low temperature natural gas, and then returns to the condenser 202 to merge with the main path vapor.
The refrigerant working medium is a nontoxic and nonflammable safe working medium. The refrigerant working medium is an environment-friendly working medium with ODP of 0 and low GWP. The refrigerating working medium is R134a, R410a or R1234yf.
The butterfly valve in the air source heat pump subsystem is a fluorine-lined butterfly valve or a turbine full-fluorine-lined butterfly valve. The check valve is a stainless steel swing check valve. The ball valve is a fixed shaft type ball valve.
The condenser, the evaporator, the reheater, the auxiliary heater, the first heat exchanger and the second heat exchanger are shell-and-tube type, tube-fin type or high-efficiency plate heat exchangers.
The cold source of the evaporator is a low-temperature heat source of air or a gate valve station. The heat source of the auxiliary heater is hot water heated by natural gas combustion.
The storage battery is an industrial lead-acid storage battery, a nickel-cadmium storage battery or a nickel-zinc storage battery.
Example 1:
in this embodiment, R134a is used as a refrigerant of an air source heat pump cycle, air is selected as a low-temperature heat source, a centripetal expander 101, a synchronous generator 103, a lead-acid storage battery 104, an explosion-proof motor 105, a screw compressor 201, a high-efficiency plate heat exchanger is selected as a reheater 106 and a first heat exchanger 108, a shell-and-tube heat exchanger is selected as an auxiliary heater 109, a condenser 202 and a second heat exchanger 203, a tube-fin heat exchanger is selected as an evaporator 205, a fixed shaft type ball valve is selected as an outlet ball valve 107, a main path ball valve 113 and a bypass ball valve 123, a stainless steel swing check valve is selected as a natural gas main path first check valve 112, a main path second check valve 114, a main path third check valve 115 and a bypass first check valve 122, a turbine full-lining fluorine butterfly valve is selected as a main path first butterfly valve 211, a main path second butterfly valve 213 and a bypass flow control valve 221, a stainless steel swing check valve is selected as a refrigerant main path check valve 212, a refrigerant bypass first check valve 222 and a refrigerant bypass second check valve 232.
The normal mode schematic of the coupling system operation of natural gas differential pressure power generation and air source heat pump is shown in fig. 2: in the natural gas pressure differential power generation subsystem, the main flow control valve 111 is fully opened, the bypass flow control valve 121 is fully closed, natural gas enters a heating main path, is heated in the condenser 202, then enters the centripetal expander 101 for expansion, and drives the output shaft to drive the synchronous generator 103 to generate power through the speed reducer 102 and is stored in the lead-acid storage battery 104.
The expanded natural gas is divided into two paths: one path enters an explosion-proof motor 105 to cool the motor, then enters a reheater 106 to reheat, and finally flows out of a downstream pipe network through an outlet ball valve 107; the other path enters the first heat exchanger 108, the cold energy of the low-temperature natural gas is applied to ice making, a water chilling unit or dry ice making, additional benefits are generated, and then the natural gas is converged with the natural gas at the outlet of a cooling pipeline of the motor 105 through the bypass first ball check valve 124, and enters the reheater 106.
In the air source heat pump subsystem, a portion of the charge in the battery 104 is now used in the screw compressor 201 to drive the air source heat pump subsystem, and the heat absorbed by the R134a refrigerant in the evaporator 205 is evaporated, and then enters the screw compressor 201 to be compressed into high temperature gas at a condensing pressure.
At this time, the R134a refrigerant is split into two paths: in the main path, the refrigerant enters the condenser 202 to condense Cheng Gaowen liquid and release heat, then a part of high-temperature liquid enters the second heat exchanger 203 to be supercooled, and enters the evaporator 205 to be evaporated after being reduced to the evaporation pressure by the main path throttle valve 204 and returns to the first air suction port of the screw compressor 201 to complete circulation; the other part of the high-temperature liquid is depressurized to the intermediate pressure by the bypass throttle valve 206, enters the second heat exchanger 203 to absorb heat and evaporate, returns to the second air suction port of the screw compressor 201, is mixed with the steam of the first air suction port, and participates in the next compression process. By-pass, the high temperature exhaust gas enters the reheater 106 through the by-pass flow control valve 221 to heat the low temperature natural gas, and then returns to the condenser 202 to merge with the main path steam.
FIG. 3 is a schematic diagram of an auxiliary mode of operation of the coupling system of the natural gas differential pressure power generation and air source heat pump of the present invention, the mode being suitable for a primary start or defrosting, cleaning, maintenance conditions of the air source heat pump subsystem;
when the air source heat pump subsystem is required to be shut down due to defrosting, cleaning and maintenance, the heat required for heating the natural gas is provided by the auxiliary heater. The auxiliary modes include expander 101, decelerator 102, generator 103, battery 104, bypass flow control valve 121, auxiliary heater 109, bypass first check valve 122, bypass ball valve 123, bypass second ball check valve 125, outlet ball valve 107.
The hot water in the auxiliary heater 109 is heated by burning part of natural gas, the incoming natural gas is heated in a water bath, the heated natural gas enters the expander 101 to expand, and the output shaft is driven to pass through the speed reducer 102 and then drive the generator 103 to generate electricity and stored in the storage battery 104. The low-temperature natural gas at the outlet of the expander 101 enters the first heat exchanger 108, and the cold energy of the low-temperature natural gas is applied to ice making, a water chilling unit or dry ice making.
Example 2:
as shown in fig. 4, the present embodiment provides a common heating mode of a coupling system of natural gas differential pressure power generation and an air source heat pump, which is suitable for the situations that the evaporation temperature is low in winter, the COP of the heat pump is low, and the condensation heat is insufficient to heat the incoming natural gas to the rated temperature, and at this time, the auxiliary heater and the condenser work simultaneously, and the natural gas flow of the main circuit and the bypass is regulated by the flow control valve; the structure thereof can be regarded as adding the auxiliary mode on the basis of embodiment 1.
When the evaporation temperature is too low, the heat pump COP is not high, the condensation heat is insufficient to heat the natural gas to a proper range, at this time, the main flow control valve 111 and the bypass flow control valve 121 can be adjusted, the natural gas flow ratio of the main and the bypass is changed, and the natural gas reaches the rated temperature under the common heating of the auxiliary heater 109 and the condenser 202.
Example 3:
fig. 5 is a schematic diagram of a defrosting mode of the coupling system of the natural gas differential pressure power generation and the air source heat pump, which is suitable for the frosting condition of the evaporator when the evaporation temperature is low. Considering that the evaporator is liable to frost due to the excessively low evaporation temperature, a hot gas defrosting mode is added in both of the embodiment 1 and the embodiment 2. At the natural gas pressure differential generating sub-system, the main path flow valve 111 is closed, the bypass flow valve 121 is fully opened, the main path ball valve 113 and the bypass first ball check valve 124 are closed, and the bypass second ball check valve 125 is opened, and at this time, the air source heat pump sub-system is disconnected from the natural gas pressure differential generating sub-system.
In the air source heat pump subsystem, the main first butterfly valve 211, the main second butterfly valve 213 and the bypass flow control valve 221 are closed for a period of time, then the bypass first butterfly valve 231 and the bypass second butterfly valve 233 are opened, the refrigerant R134a is compressed into high-temperature high-pressure gas through the screw compressor 201, enters the evaporator 205 to condense and release heat, and after the frost layer of the evaporator 205 is melted, enters the constant-pressure throttle valve 207, and then enters the screw compressor 201, and the defrosting cycle is completed. Then the bypass first butterfly valve 231 and the bypass second butterfly valve 233 are closed, the main first butterfly valve 211, the main second butterfly valve 213 and the bypass flow control valve 221 are opened, at this time, the air source heat pump subsystem is coupled with the natural gas differential pressure power generation subsystem again, and the common heating mode is entered, and the bypass flow control valve 121 can also be closed to enter the normal working mode.
The technical effects of the coupling system of the natural gas differential pressure power generation and the air source heat pump are verified:
with a certain valve stationFor example, the natural gas pressure reducing system has a natural gas flow of 10 ten thousand Nm 3 And/h, the pressure is 2.2MPaA, the temperature is 20 ℃, and the working medium components are as follows: 94.849% of methane, 2.604% of ethane, 1.400% of carbon dioxide and 1.148% of other materials.
If the natural gas is directly expanded to 0.6MPaA, about 2190kW can be generated, 1900kW of heat is needed for rewarming to 0 ℃, and 210Nm of natural gas is consumed 3 And/h, the total reheat cost is about 525 yuan/h.
If the system scheme in the embodiment 1 is adopted, the air source heat pump is firstly used for preheating to 60 ℃, the preheating amount is 1950kW, and the power consumption of the motor is 604kW. The generating capacity of the expander is improved to 2540kW, and the generating capacity of the expander is increased by 16%. The preheating cost is about 203 yuan/h, 85 percent and 60 percent of the preheating cost is saved compared with an electric heater and a water bath heater, and the system economy is improved greatly.
The above specific embodiments have been described in detail for the purpose, technical solution and beneficial effects of the present invention, and the above embodiments and modes can be reasonably combined, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be within the protection scope of the present invention.
Claims (10)
1. The coupling system of the natural gas pressure difference power generation and the air source heat pump comprises a natural gas pressure difference power generation subsystem and an air source heat pump subsystem, and is characterized in that the air source heat pump subsystem is driven by electric quantity generated by the natural gas pressure difference power generation subsystem, heat generated by the air source heat pump subsystem is utilized to heat incoming natural gas, the enthalpy value of the incoming natural gas is improved, and the power generation capacity of the natural gas pressure difference power generation subsystem is increased; and a part of compressor exhaust gas is led out from the air source heat pump subsystem and used for reheating the expanded low-temperature natural gas, so that the temperature of the low-temperature natural gas meets the requirement of being sent into a downstream pipe network.
2. The coupling system of natural gas differential pressure power generation and air source heat pump according to claim 1, wherein the natural gas differential pressure power generation subsystem comprises a natural gas main circuit and a power generation branch circuit;
the natural gas main path comprises a main path flow control valve (111), a condenser (202), a main path first check valve (112), an expander (101), a main path ball valve (113), a motor (105), a main path second check valve (114), a reheater (106), a main path third check valve (115) and an outlet ball valve (107) which are connected in sequence; the main way ball valve (113), the motor (105) and the main way second check valve (114) are connected in series with a branch pipeline, and a bypass ball valve (123), a first heat exchanger (108) and a bypass first ball check valve (124) are sequentially arranged on the branch pipeline; the bypass first ball check valve (124) is sequentially connected with the reheater (106) and the main third check valve (115), and one side of the connecting pipeline is provided with a second ball check valve (125) connected in parallel and then is connected with the outlet ball valve (107);
the power generation branch circuit comprises an expander (101), a speed reducer (102), a generator (103) and a motor (105) which are sequentially connected with the main flow path, wherein the generator (103) is connected with a storage battery (104).
3. The coupling system of the natural gas differential pressure power generation and the air source heat pump according to claim 2, wherein the natural gas differential pressure power generation subsystem further comprises a natural gas bypass, and the natural gas bypass is connected in parallel to both ends of the main flow control valve (111) and the main first check valve (112), and comprises a bypass flow control valve (121), an auxiliary heater (109) and a bypass first check valve (122) which are sequentially connected.
4. A coupling system of natural gas differential pressure power generation and air source heat pump according to claim 2, wherein the natural gas flow entering the condenser (202) or the auxiliary heater (109) is regulated by the main flow control valve (111) and the bypass flow control valve (121) to raise the temperature and increase the enthalpy, then the natural gas is introduced into the expander (101) to expand and apply work, the output shaft is driven to drive the generator (103) to generate power by the speed reducer (102), one part of electric quantity is stored in the storage battery (104), and the other part of electric quantity is used for meeting the requirement that the motor (105) drives the air source heat pump subsystem;
the low-temperature natural gas expanded by the expander (101) enters two branches: one is to enter the motor (105) to cool the motor, then the motor is reheated by the reheater (106) and then flows into a downstream pipe network through the outlet ball valve (107), and the other is to enter the first heat exchanger (108) to utilize cold energy, and then the natural gas which is bypassed through the first ball check valve (124) and comes out of the cooling motor (105) is converged to enter the reheater (106).
5. A coupling system of natural gas differential pressure power generation and air source heat pump according to claim 3, wherein the reheater (106), the first heat exchanger (108), the auxiliary heater (109) and the condenser (202) are shell-and-tube, tube-fin or high-efficiency plate heat exchangers.
6. A coupling system of natural gas pressure difference power generation and air source heat pump according to claim 3, wherein the heat source of the auxiliary heater (109) is hot water heated by natural gas combustion.
7. The coupling system of natural gas differential pressure power generation and air source heat pump according to claim 2, wherein the air source heat pump subsystem comprises a heat pump main circuit, an air injection enthalpy-increasing branch circuit and an exhaust gas reheating branch circuit;
the main circuit of the heat pump comprises a compressor (201), a main circuit first butterfly valve (211), a condenser (202), a second heat exchanger (203), a main circuit throttle valve (204), a main circuit first check valve (212), an evaporator (205) and a main circuit second butterfly valve (213) which are sequentially connected, wherein the main circuit second butterfly valve (213) is connected with the compressor (201) in a return way;
the condenser (202) and the second heat exchanger (203) are connected in parallel with a branch pipeline, a throttle valve (206) is arranged on the branch pipeline, and the compressor (201), the main first butterfly valve (211), the condenser (202), the throttle valve (206) and the second heat exchanger (203) are sequentially connected to form an enhanced vapor injection branch;
a circulation loop is arranged between the compressor (201) and the reheater (106), and a bypass flow control valve (221) and a bypass first check valve (222) are arranged on the circulation loop; the compressor (201), the bypass flow control valve (221), the reheater (106) and the bypass first check valve (222) are sequentially connected to form an exhaust reheating branch.
8. The coupling system of natural gas differential pressure power generation and air source heat pump of claim 7, wherein the air source heat pump subsystem further comprises a hot gas defrosting branch comprising a compressor (201), a bypass first butterfly valve (231), a bypass second check valve (232), an evaporator (205), a constant pressure valve (207) and a bypass second butterfly valve (223) connected in sequence.
9. The coupling system of natural gas differential pressure power generation and air source heat pump as recited in claim 7, wherein the reheater (106), second heat exchanger (203), evaporator (205) are shell-and-tube, tube-and-fin, or high efficiency plate heat exchangers.
10. A natural gas differential pressure power generation and air source heat pump coupling system as defined in claim 7 wherein the heat source of the evaporator (205) is from air or other cryogenic heat sources of the valve station, the evaporation temperature of which varies with the heat source temperature.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117108381A (en) * | 2023-07-21 | 2023-11-24 | 北京市煤气热力工程设计院有限公司 | Natural gas differential pressure power generation and hydrogen production system capable of recycling coupling pressure energy |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117108381A (en) * | 2023-07-21 | 2023-11-24 | 北京市煤气热力工程设计院有限公司 | Natural gas differential pressure power generation and hydrogen production system capable of recycling coupling pressure energy |
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