Efficient absorption heat pump system with low start-stop frequency during variable load of gas-fired boiler

Abstract

The invention discloses an efficient absorption heat pump system with low start-stop frequency during variable load of a gas-fired boiler, and belongs to the technical field of absorption heat pumps. Comprising a multi-module absorption heat pump system, and a gas-fired boiler flue gas total heat recovery system, a heat storage and air regulation system and a flue gas condensate water and heat supply network return water heating system which are respectively connected with the multi-module absorption heat pump system; according to the efficient absorption type heat pump system with the low start-stop frequency during the variable load of the gas-fired boiler, a single generator and a single absorber of a traditional absorption type heat pump are changed into a generator set and an absorber set of three modules, and a heat storage and air regulation system is configured; the problems that COP of the absorption heat pump drops suddenly during load fluctuation, driving force is insufficient and a generator is overheated and shuts down frequently are solved while effective recycling of smoke latent heat is guaranteed, and the operation stability of the gas-fired boiler coupling absorption heat pump system is improved.

Description

Technical Field

[0001] The invention relates to a high-efficiency absorption heat pump system with low start-stop frequency when a gas boiler has variable load, and belongs to the technical field of absorption heat pumps. Background Art

[0002] As the number of industrial gas-fired boilers continues to increase, there's a need to improve their energy efficiency and recover and utilize waste heat from flue gases. Existing conventional heat exchanger waste heat recovery solutions can recover a small amount of waste heat to a certain extent, but they can only reduce the exhaust temperature to around 60°C. Furthermore, the water vapor in the exhaust contains a large amount of latent heat of vaporization, which is then released into the environment, creating a "white smoke" effect.

[0003] Absorption heat pump technology can reduce the boiler exhaust temperature to around 30°C, effectively recovering the latent heat of the flue gas. Gas-fired boiler-coupled absorption heat pump technology is often used in industrial park heating. However, in some industrial parks where multiple types of industrial enterprises are concentrated, differences in user production processes and duration lead to large load fluctuations, resulting in differences in the dynamic response of the boiler and heat pump, sudden drops and increases in load, and thus frequent shutdowns and reduced COP during the operation of the gas-fired boiler-coupled absorption heat pump system. Therefore, in order to solve the above problems, it is urgent to design a high-efficiency absorption heat pump system with low start-stop frequency when the gas-fired boiler has variable load. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a high-efficiency absorption heat pump system with low start-stop frequency when the gas boiler has variable load. The single generator and absorber of the traditional absorption heat pump are replaced by a three-module generator group and absorber group, and a heat storage and air regulation system is configured, thereby improving the operating stability of the gas boiler coupled absorption heat pump system.

[0005] The present invention provides a high-efficiency absorption heat pump system with low start-stop frequency when the gas boiler has variable load, comprising a multi-module absorption heat pump system, and a gas boiler flue gas full heat recovery system, a heat storage and air conditioning system, and a flue gas condensate and heat network return water heating system, each of which is connected to the multi-module absorption heat pump system. The multi-module absorption heat pump system includes a generator group, an absorber group, an evaporator and a condenser; the generator group and the absorber group are connected via a solution heat exchanger, a solution pump and a solution valve; the generator group is connected to the condenser via a vapor compression pump; the condenser is connected to the evaporator via an expansion valve; the refrigerant vapor outlet of the evaporator is connected to the refrigerant vapor inlet of the absorber group; The gas boiler flue gas full heat recovery system includes a generator group, an evaporator, a water collector and a gas boiler; the flue gas inlet of the generator group is connected to the exhaust pipeline of the gas boiler through a flue gas valve; the flue gas outlet of the generator group is connected to the air inlet of the evaporator; and a water collector is installed at the air outlet of the evaporator; The heat storage and air conditioning system includes a gas boiler, an electric heater, a high-temperature molten salt tank, a low-temperature molten salt tank and an air-molten salt heat exchanger; the low-temperature molten salt tank is connected to the high-temperature molten salt tank via the electric heater; the low-temperature molten salt tank and the high-temperature molten salt tank are respectively connected to the heat exchange port of the air-molten salt heat exchanger; the air outlet of the air-molten salt heat exchanger is connected to the exhaust pipeline of the gas boiler via a pipeline; The flue gas condensate and heat network return water heating system includes an absorber group, a condenser, a water collector and a gas boiler; the hot water outlet of the absorber group is connected to the hot water inlet of the condenser; the heat network return water inlet of the absorber group is connected to the heat network return water pipeline through a return water valve.

[0006] Furthermore, the superheated steam outlet of the generator group is connected to the superheated steam inlet of the condenser through a steam compression pump; the heat pump working fluid water outlet of the condenser is connected to the heat pump working fluid water inlet of the evaporator through an expansion valve.

[0007] Furthermore, the generator group is composed of multiple generator modules, the absorber group is composed of multiple absorber modules, and the multiple generator modules correspond to the multiple absorber modules one by one; the lithium bromide concentrated solution outlet of the generator module is connected to the lithium bromide concentrated solution inlet of the absorber module through a solution heat exchanger and a solution valve in sequence; the lithium bromide dilute solution outlet of the absorber module is connected to the lithium bromide dilute solution inlet of the generator module through a solution pump and a solution heat exchanger in sequence.

[0008] Furthermore, the flue gas generated by the evaporator is discharged into the atmosphere after passing through a water collector.

[0009] Furthermore, the drain outlet of the water collector is connected to the return water pipeline of the heating network, and the water collector collects a large amount of condensed water in the flue gas and merges it into the return water of the heating network.

[0010] Furthermore, the outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the electric heater; the molten salt outlet of the electric heater is connected to the inlet of the high-temperature molten salt tank; the inlet of the low-temperature molten salt tank and the outlet of the high-temperature molten salt tank are respectively connected to the heat exchange outlet and heat exchange inlet of the air-molten salt heat exchanger.

[0011] Furthermore, the air inlet of the air-molten salt heat exchanger is connected to an air pipeline.

[0012] Furthermore, the hot water outlet of the condenser is connected to the hot water inlet of the gas boiler via a return water pipeline.

[0013] Compared with the prior art, the high-efficiency absorption heat pump system with low start-stop frequency when the gas boiler has variable load of the present invention changes the single generator and absorber of the traditional absorption heat pump into a three-module generator group and absorber group, and is equipped with a heat storage and air conditioning system; when the system is running, the corresponding generator module flue gas valve and absorber module return water valve are opened or closed according to the real-time load, so that the load rate of the absorption heat pump is always greater than 66.66%, preventing insufficient driving force, a sharp drop in COP, and even frequent shutdowns; when the boiler load rises suddenly, the amount of air heated by the heat storage and air conditioning system is adjusted in advance according to the heat pump load regulation rate until the load response time ends, to prevent the generator from overheating and shutting down; while ensuring the effective recovery and utilization of the flue gas latent heat, it solves the problems of sudden drop in COP of the absorption heat pump, insufficient driving force and frequent shutdown of the generator due to overheating when the load fluctuates, thereby improving the operating stability of the gas boiler coupled absorption heat pump system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 This is a schematic structural diagram of the multi-module absorption heat pump system of the present invention.

[0016] Figure 3 It is a structural schematic diagram of the gas boiler flue gas full heat recovery system of the present invention.

[0017] Figure 4 It is a structural schematic diagram of the heat storage and air regulating system of the present invention.

[0018] Figure 5 It is a schematic diagram of the structure of the flue gas condensate water and heat network return water heating system of the present invention.

[0019] The components in the accompanying drawings are marked as follows: 1 is the generator group, 1-1 is the generator module a, 1-2 is the generator module b, 1-3 is the generator module c, 2 is the absorber group, 2-1 is the absorber module a, 2-2 is the absorber module b, 2-3 is the absorber module c, 3 is the evaporator, 4 is the condenser, 5 is the solution heat exchanger of the generator module a, 6 is the solution pump of the generator module a, 7 is the solution valve of the generator module a, 8 is the solution heat exchanger of the generator module b, 9 is the solution pump of the generator module b, 10 is the solution valve of the generator module b, 11 is the solution heat exchanger of the generator module c, 12 is the generator module c solution pump, 13 is the c solution valve of the generator module, 14 is the steam compression pump, 15 is the expansion valve, 16 is the water collector, 17 is the gas boiler, 18 is the electric heater, 19 is the high-temperature molten salt tank, 20 is the low-temperature molten salt tank, 21 is the air-molten salt heat exchanger, 22 is the flue gas valve a of the generator module, 23 is the flue gas valve b of the generator module, 24 is the flue gas valve c of the generator module, 25 is the return water valve a of the absorber module, 26 is the return water valve b of the absorber module, 27 is the return water valve c of the absorber module, 28 is the return water pipeline of the heat network, 29 is the air pipeline, 30 is the exhaust pipeline, 31 is the return water pipeline, and 32 is the exhaust pipe. DETAILED DESCRIPTION

[0020] Example 1: like Figures 1 to 5 The high-efficiency absorption heat pump system with low start-stop frequency for gas boilers with variable loads shown includes a multi-module absorption heat pump system, and a gas boiler flue gas full heat recovery system, a heat storage and air conditioning system, and a flue gas condensate and heat network return water heating system, each of which is connected to the multi-module absorption heat pump system. The multi-module absorption heat pump system includes a generator group 1, an absorber group 2, an evaporator 3 and a condenser 4; the generator group 1 and the absorber group 2 are connected via a solution heat exchanger, a solution pump and a solution valve; the superheated steam outlet of the generator group 1 is connected to the superheated steam inlet of the condenser 4 via a steam compression pump 14; the heat pump working medium water outlet of the condenser 4 is connected to the heat pump working medium water inlet of the evaporator 3 via an expansion valve 15; the refrigerant steam outlet of the evaporator 3 is connected to the refrigerant steam inlet of the absorber group 2; Wherein, the generator group 1 is composed of a plurality of generator modules, and the absorber group 2 is composed of a plurality of absorber modules, and the plurality of generator modules correspond to the plurality of absorber modules one-to-one; the lithium bromide concentrated solution outlet of the generator module is connected to the lithium bromide concentrated solution inlet of the absorber module in sequence through a solution heat exchanger and a solution valve; the lithium bromide dilute solution outlet of the absorber module is connected to the lithium bromide dilute solution inlet of the generator module in sequence through a solution pump and a solution heat exchanger; thereby completing the solution exchange between the generator module and the absorber module; Specifically, the generator group includes a generator module a1-1, a generator module b1-2 and a generator module c1-3; the absorber group includes an absorber module a2-1, an absorber module b2-2 and an absorber module c2-3; The lithium bromide concentrated solution outlets of the generator module a1-1, the generator module b1-2 and the generator module c1-3 are respectively connected to the concentrated solution inlets of the generator module a solution heat exchanger 5, the generator module b solution heat exchanger 8 and the generator module c solution heat exchanger 11; the concentrated solution outlets of the generator module a solution heat exchanger 5, the generator module b solution heat exchanger 8 and the generator module c solution heat exchanger 11 are respectively connected to the inlets of the generator module a solution valve 7, the generator module b solution valve 10 and the generator module c solution valve 13; the outlets of the generator module a solution valve 7, the generator module b solution valve 10 and the generator module c solution valve 13 are respectively connected to the lithium bromide concentrated solution inlets of the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3; The lithium bromide dilute solution outlets of the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 are respectively connected to the inlets of the generator module a solution pump 6, the generator module b solution pump 9 and the generator module c solution pump 12; the outlets of the generator module a solution pump 6, the generator module b solution pump 9 and the generator module c solution pump 12 are respectively connected to the dilute solution inlets of the generator module a solution heat exchanger 5, the generator module b solution heat exchanger 8 and the generator module c solution heat exchanger 11; the dilute solution outlets of the generator module a solution heat exchanger 5, the generator module b solution heat exchanger 8 and the generator module c solution heat exchanger 11 are respectively connected to the lithium bromide dilute solution inlets of the generator module a1-1, the generator module b1-2 and the generator module c1-3; Design the dilute lithium bromide solution in generator module a1-1, generator module b1-2, and generator module c1-3 to have the same concentration and quality, and the concentrated lithium bromide solution in absorber module a2-1, absorber module b2-2, and absorber module c2-3 to have the same concentration and quality; The gas boiler flue gas full heat recovery system includes a generator group 1, an evaporator 3, a water collector 16, and a gas boiler 17. The flue gas inlet of the generator group 1 is connected to the flue gas exhaust pipeline 30 of the gas boiler 17 through a flue gas valve. The flue gas outlet of the generator group 1 is connected to the air inlet of the evaporator 3. The water collector 16 is installed at the air outlet of the evaporator 3. The flue gas generated by the evaporator 3 is discharged into the atmosphere after passing through the water collector 16. The water collector 16 installed on the evaporator 3 can collect a large amount of condensed water in the flue gas and add it to the heat network return water pipeline 28. Specifically, the smoke exhaust port of the gas boiler 17 is connected to the smoke inlets of the generator module smoke valve a22, the generator module smoke valve b23, and the generator module smoke valve c24 through the smoke exhaust pipeline 30. The smoke outlets of the generator module smoke valve a22, the generator module smoke valve b23, and the generator module smoke valve c24 are respectively connected to the smoke inlets of the generator module a1-1, the generator module b1-2, and the generator module c1-3. The smoke outlets of the generator module a1-1, the generator module b1-2, and the generator module c1-3 are connected to the air inlet of the evaporator 3. The smoke outlet of the evaporator 3 is connected to the exhaust pipe 32, and the exhaust pipe 32 passes through the water collector 16 and extends to the atmosphere. The heat storage and air conditioning system includes a gas boiler 17, an electric heater 18, a high-temperature molten salt tank 19, a low-temperature molten salt tank 20 and an air-molten salt heat exchanger 21; the outlet of the low-temperature molten salt tank 20 is connected to the molten salt inlet of the electric heater 18; the molten salt outlet of the electric heater 18 is connected to the inlet of the high-temperature molten salt tank 19; the inlet of the low-temperature molten salt tank 20 and the outlet of the high-temperature molten salt tank 19 are respectively connected to the heat exchange outlet and heat exchange inlet of the air-molten salt heat exchanger 21; the air inlet of the air-molten salt heat exchanger 21 is connected to an air pipeline 29; the air outlet of the air-molten salt heat exchanger 21 is connected to the exhaust pipeline 30 of the gas boiler 17 via a pipeline; The flue gas condensate and heat network return water heating system includes an absorber group 2, a condenser 4, a water collector 16, and a gas boiler 17; the hot water outlet of the absorber group 2 is connected to the hot water inlet of the condenser 4; the absorber group 2 is connected to the heat network return water pipeline 28 via a return water valve; the hot water outlet of the condenser 4 is connected to the hot water inlet of the gas boiler 17 via a return water pipeline 31; the drain outlet of the water collector 16 is connected to the heat network return water pipeline 28; Specifically, the water collector 16 recovers the condensed water in the flue gas and incorporates it into the heat network return water pipeline 28, and is connected to the heat network return water inlet of the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 through the absorber module return water valve a25, the absorber module return water valve b26 and the absorber module return water valve c27 respectively. The hot water outlets of the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 are connected to the hot water inlet of the condenser 4.

[0021] The working principle of the high-efficiency absorption heat pump system with low start-stop frequency when the gas boiler has variable load is as follows: The dilute lithium bromide solution in the generator module a1-1, the generator module b1-2 and the generator module c1-3 is heated and concentrated by the flue gas. After the dilute solution becomes a concentrated solution, it enters the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 respectively; the concentrated solution in the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 releases absorption heat, thereby heating the return water of the heat network. After the concentrated solution becomes a dilute solution, it enters the generator module a1-1, the generator module b1-2 and the generator module c 1-3; the superheated steam generated in the generator module a1-1, the generator module b1-2 and the generator module c1-3 is pressurized by the steam compression pump 14 and enters the condenser 4; in the condenser 4, it exchanges heat with the return water of the heat network, is cooled and becomes the heat pump working medium water, and is reduced in pressure by the expansion valve 15 and enters the evaporator 3; then, in the evaporator 3, it is heated by the flue gas and becomes refrigerant vapor, which enters the absorber module a2-1, the absorber module b2-2 and the absorber module c2-3 respectively to dilute the lithium bromide concentrated solution and release heat, thus forming a cycle.

[0022] During stable operation of the gas boiler 17, when the load is greater than 2 / 3, the flue gas is evenly divided into three paths and enters the generator module a1-1, the generator module b1-2, and the generator module c1-3. After heating the dilute lithium bromide solution, the flue gas temperature is reduced. Finally, the flue gas enters the evaporator 3 and is cooled by the heat pump working fluid water. The flue gas temperature can be reduced to 30°C, realizing the latent heat recovery of the gas boiler flue gas. When the load is greater than 1 / 3 and less than or equal to 2 / 3, the generator module c1-3 and the absorber module c 2-3 are turned off; When the load drops below 1 / 3, the generator module b1-2 and the absorber module b2-2 are turned off, and the generator module c1-3 and the absorber module c2-3 are also turned off. This ensures that the load rate of the absorption heat pump is always greater than 66.66%, preventing insufficient driving force of the heat pump, a sharp drop in COP, and even frequent shutdowns. At the same time, by quickly shutting down the corresponding modules in generator group 1 and absorber group 2, the problem of system oscillation caused by the absorption heat pump's inability to track the load in time due to delayed response can be solved.

[0023] When the boiler needs to increase its load quickly due to a sudden increase in heating demand, the corresponding modules of generator group 1 and absorber group 2 should be turned on in advance to prevent overheating of generator 1; the air is heated by the air-molten salt heat exchanger 21 and mixed with the flue gas at the outlet of the gas boiler 17 and evenly distributed into each module in the generator group 1; when the boiler load is increased, the heat storage and air conditioning system is closed; the air supply volume and the heat pump start-up time are determined by the load regulation rate of the absorption heat pump; the capacity of the high-temperature molten salt tank 19 and the low-temperature molten salt tank 20 are both determined by the maximum load mutation; at the same time, the electric heater 18 heats the molten salt to the maximum heat storage capacity of the high-temperature molten salt tank 19 in time when the heat storage and air conditioning system is closed.

[0024] The above embodiments are only preferred implementations of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A high-efficiency absorption heat pump system with low start-stop frequency for a gas boiler under variable load conditions, characterized by: It includes a multi-module absorption heat pump system, and a gas boiler flue gas full heat recovery system, a heat storage and air conditioning system, a flue gas condensate water and heat network return water heating system respectively connected to the multi-module absorption heat pump system; The multi-module absorption heat pump system includes a generator group, an absorber group, an evaporator and a condenser; the generator group and the absorber group are connected via a solution heat exchanger, a solution pump and a solution valve; the generator group is connected to the condenser via a vapor compression pump; the condenser is connected to the evaporator via an expansion valve; the refrigerant vapor outlet of the evaporator is connected to the refrigerant vapor inlet of the absorber group; The gas boiler flue gas full heat recovery system includes a generator group, an evaporator, a water collector and a gas boiler; the flue gas inlet of the generator group is connected to the exhaust pipeline of the gas boiler through a flue gas valve; the flue gas outlet of the generator group is connected to the air inlet of the evaporator; and a water collector is installed at the air outlet of the evaporator; The heat storage and air conditioning system includes a gas boiler, an electric heater, a high-temperature molten salt tank, a low-temperature molten salt tank and an air-molten salt heat exchanger; the low-temperature molten salt tank is connected to the high-temperature molten salt tank via the electric heater; the low-temperature molten salt tank and the high-temperature molten salt tank are respectively connected to the heat exchange port of the air-molten salt heat exchanger; the air outlet of the air-molten salt heat exchanger is connected to the exhaust pipeline of the gas boiler via a pipeline; The flue gas condensate and heat network return water heating system includes an absorber group, a condenser, a water collector and a gas boiler; the hot water outlet of the absorber group is connected to the hot water inlet of the condenser; the heat network return water inlet of the absorber group is connected to the heat network return water pipeline through a return water valve.

2. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1, characterized in that: The superheated steam outlet of the generator group is connected to the superheated steam inlet of the condenser through a steam compression pump; the heat pump working medium water outlet of the condenser is connected to the heat pump working medium water inlet of the evaporator through an expansion valve.

3. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1 or 2, characterized in that: The generator group is composed of multiple generator modules, and the absorber group is composed of multiple absorber modules, and the multiple generator modules correspond to the multiple absorber modules one by one; the lithium bromide concentrated solution outlet of the generator module is connected to the lithium bromide concentrated solution inlet of the absorber module through a solution heat exchanger and a solution valve in sequence; the lithium bromide dilute solution outlet of the absorber module is connected to the lithium bromide dilute solution inlet of the generator module through a solution pump and a solution heat exchanger in sequence.

4. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1 is characterized in that: The flue gas generated by the evaporator is discharged into the atmosphere after passing through a water collector.

5. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1 or 4, characterized in that: The drain outlet of the water collector is connected to the heat network return pipeline.

6. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1, characterized in that: The outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the electric heater; the molten salt outlet of the electric heater is connected to the inlet of the high-temperature molten salt tank; the inlet of the low-temperature molten salt tank and the outlet of the high-temperature molten salt tank are respectively connected to the heat exchange outlet and heat exchange inlet of the air-molten salt heat exchanger.

7. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1, characterized in that: The air inlet of the air-molten salt heat exchanger is connected to an air pipeline.

8. The high-efficiency absorption heat pump system with low start-stop frequency under variable load of a gas boiler according to claim 1, characterized in that: The hot water outlet of the condenser is connected to the hot water inlet of the gas boiler via a return water pipeline.

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