A gas engine driven air source heat pump drying unit

Abstract

This utility model discloses a gas engine-driven air source heat pump dryer unit. This unit combines a gas engine with an air source heat pump and includes multiple operating systems: a gas engine system, a hot air circulation system, an evaporative compression heat pump system, and an antifreeze circulation system. The unit heats the circulating air through segmented heat exchange via a finned condenser and a waste heat exchanger. It also features a waste heat electric two-way valve and a heat dissipation electric two-way valve to distribute flow according to actual heat exchange requirements, balancing unit heat dissipation with control of circulating air outlet temperature and humidity. This utility model fully and rationally utilizes the waste heat from the gas engine to heat the circulating air, improving the overall thermal efficiency of the system, significantly enhancing drying capacity, and meeting the high-temperature heat requirements of processes such as tobacco processing.

Description

Technical Field

[0001] This utility model relates to a drying unit, and more particularly to an air source heat pump drying unit. Background Technology

[0002] The main principle of an electrically driven air source heat pump is based on a heat pump cycle system. It uses an electric motor to drive a compressor to extract low-temperature heat energy from the environment and raise it to a high temperature, then releases the heat through a heat exchanger.

[0003] Therefore, the electrically driven air source heat pump dryer developed based on this principle has significant energy-saving benefits. It only requires a small amount of electricity to absorb a large amount of heat energy from the air, resulting in low power consumption and wide application in drying grains, fruits, vegetables, and other fields. However, with the increasing variety of materials to be dried and the increasing complexity of environmental conditions in recent years, electrically driven air source heat pump dryers are facing more and more limitations. Compared with other traditional drying equipment, the purchase cost of electrically driven air source heat pump drying is relatively high, requiring the construction of a dedicated drying room. Secondly, it is quite sensitive to ambient temperature; the efficiency of the heat pump is affected by the ambient temperature, especially in low-temperature environments, where its performance may decline, limiting its application in cold regions. In addition, an unstable power supply is required during the operation of the electrically driven air source heat pump. Unstable voltage may damage the equipment, and the resulting unstable and discontinuous heating has a significant impact on the drying effect. For large-scale electric drying of materials, it also leads to the problem of increasing power capacity. Therefore, electrically driven air source heat pump dryers also have some shortcomings in drying technology.

[0004] US Patent Publication No. US20190032597A1 discloses "A method for controlling the temperature of a waste heat recovery system associated with an internal combustion engine, the waste heat recovery system including a working fluid loop; at least one evaporator; an expander; a condenser; and a pump arranged to pump the working fluid through the loop, wherein the at least one evaporator is arranged for heat exchange between the working fluid and a heat source associated with the internal combustion engine, and wherein the condenser of the waste heat recovery system is connected to a cooling system. The method includes the steps of: determining whether the internal combustion engine associated with the waste heat recovery system is about to be shut down; and controlling the temperature in the waste heat recovery system based on whether the internal combustion engine is about to be shut down. However, this device has the following problems:

[0005] (1) The cooling fluid temperature is reduced by the radiator to improve the heat dissipation efficiency. However, in high temperature environments or when the radiator is dusty or malfunctioning, the heat dissipation effect may decrease, causing the system cooling speed to fail to meet the temperature control requirements before shutdown, which poses a risk of overheating.

[0006] (2) Low waste heat recovery efficiency. This device emphasizes maintaining high temperature in non-shutdown mode to optimize recovery efficiency. However, in scenarios with frequent start-stop (such as urban traffic), the system may experience increased energy loss due to repeated cooling and heating, and the actual energy efficiency improvement may be lower than expected.

[0007] Chinese patent CN201720817334.7 discloses a "Gas Engine Heat Pump System for High-Efficiency Waste Heat Utilization," comprising a compression heat pump system, a waste heat recovery system, an auxiliary evaporation system, a defrosting system, and a user water supply and return system. This invention operates in two modes: cooling and heating. The heat pump unit switches between these modes via a four-way valve. The waste heat recovery system ensures stable engine operation during winter heating. Depending on the outdoor ambient temperature and user needs, the engine's waste heat can be adjusted for defrosting and auxiliary evaporation, ensuring normal unit operation. Waste heat can be used to heat heating water, reducing unit energy consumption and increasing hot water temperature. In summer, when producing chilled water, waste heat can also be used to produce domestic hot water, improving the heat pump unit's coefficient of performance and primary energy utilization rate. However, this device has the following problems:

[0008] (1) The device has a complex pipeline layout, which increases the difficulty of equipment installation. The large number of valve nodes can easily lead to leakage risks and high maintenance costs. The device achieves the operation modes of heating, heating + domestic hot water, and cooling + domestic hot water by switching multiple valves. It is highly dependent on the control logic program. If the switching operation is frequent, it is easy to cause mode switching failure and affect the heating / cooling efficiency.

[0009] (2) The waste heat of the engine is used to produce domestic hot water in summer. However, the heat pump system consumes a lot of energy in the cooling mode. If the amount of waste heat recovery is insufficient or conflicts with the cooling cycle, the overall energy efficiency of the unit will be limited.

[0010] (3) When operating in a low-temperature outdoor environment, the auxiliary evaporation system or defrosting system needs to be started, relying on the engine waste heat to maintain the operation of the heat pump. If the engine waste heat is insufficient to meet the auxiliary evaporation or defrosting requirements at extreme low temperatures, additional energy may be required, resulting in a decrease in the energy efficiency of the system. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a gas engine-driven air source heat pump dryer that improves the unit's energy utilization rate, meets temperature requirements at different stages, achieves efficient utilization of thermal energy, and significantly enhances the system's heating performance.

[0012] To solve the technical problems existing in current construction, this utility model adopts the following technical solution:

[0013] This utility model discloses a gas engine-driven air source heat pump dryer unit, comprising a gas engine system, a hot air circulation system, an evaporative compression heat pump system, and an antifreeze circulation system; the gas engine system includes a gas engine and a compressor;

[0014] The hot air circulation system includes two finned waste heat exchangers. The exhaust ports of the two finned waste heat exchangers are connected in sequence via second pipes to a main fan, a dense drying oven, a dehumidification valve, a dehumidifying fan, a high-temperature channel of a sensible heat exchanger, a high-temperature air duct of a finned evaporator, an air inlet of a finned heat exchanger, and an air inlet of a low-temperature channel of a sensible heat exchanger. The exhaust ports of the low-temperature channels of the two sensible heat exchangers are open to the atmosphere. One end of each of the two third pipes is connected to the second pipe located between the exhaust port of each dense drying oven and the dehumidification valve, and the other end is connected in sequence to a finned condenser and the air inlet of a finned waste heat exchanger. Two fresh air pipes, one end of which is open to the atmosphere, are connected in sequence to a fresh air fan and a fresh air valve, and the other end is connected to the air inlet of either the first or second finned condenser.

[0015] The evaporative compression heat pump system includes the gas engine. The exhaust port of the compressor is connected to the inlet of the oil-gas separator. The oil return port of the oil-gas separator is connected to the oil return port of the compressor via an oil return pipe. The outlet of the oil-gas separator is divided into two paths and connected to the inlet of the refrigerant passage of the first finned condenser and the second finned condenser, respectively. The outlets of the refrigerant passages of the first finned condenser and the second finned condenser merge and are connected to the inlet pipe of the liquid receiver. The outlet pipe of the liquid receiver is connected to the dryer filter and the liquid supply solenoid valve in sequence. The outlet B of the liquid supply solenoid valve is divided into two paths. The outlet of each liquid supply solenoid valve is connected to the sight glass, the thermal expansion valve, and the liquid phase pipeline of the finned evaporator in sequence via the liquid supply solenoid valve outlet pipeline. The liquid phase pipelines of the two finned evaporators merge and are connected to the inlet of the gas-liquid separator, the outlet of the gas-liquid separator, and the suction end of the compressor in sequence.

[0016] The antifreeze circulation system includes the cylinder liner outlet of the gas engine, port A of a three-way valve, port B of a three-way valve, an internal circulation electric two-way valve, an antifreeze circulating water pump, a flue gas heat exchanger coolant passage, and a gas engine coolant inlet, all connected sequentially through a first pipeline. The gas engine exhaust port is connected to the flue gas passage inlet of the flue gas heat exchanger, and the exhaust port of the flue gas heat exchanger is open to the atmosphere. Port C of the three-way valve is divided into two three-way branches. The first three-way branch is connected sequentially to the waste heat electric two-way valve, the liquid phase pipelines of the two finned waste heat heat exchangers, and the first pipeline located between the antifreeze circulating water pump and the internal circulation electric two-way valve. The second three-way branch is connected sequentially to the heat dissipation electric two-way valve, the liquid phase pipelines of the two finned heat dissipation heat exchangers, and the first pipeline located between the antifreeze circulating water pump and the internal circulation electric two-way valve.

[0017] The beneficial effects of this invention are as follows: This drying unit fully utilizes the antifreeze circulation system to recover waste heat from the gas engine cylinder liners and flue gas, not only avoiding energy waste but also improving energy utilization efficiency. During the hot air circulation phase, the unit fully utilizes the antifreeze circulation system to circulate the internal antifreeze to the finned waste heat exchanger, where it exchanges heat with the circulating air to raise the air temperature and achieve a suitable outlet air temperature to meet the outlet air requirements at different stages.

[0018] The unit is also equipped with a heat dissipation electric solenoid valve and a waste heat electric solenoid valve, which fully distribute the circulation volume of antifreeze in different pipelines at different stages of the unit's drying process, thereby achieving control of the unit's outlet air temperature and heat dissipation.

[0019] The antifreeze circulation system described in this invention includes an internal circulation electric two-way valve, a waste heat electric two-way valve, and a cooling electric two-way valve, enabling the recovery and utilization of waste heat from the gas engine and improving the unit's energy efficiency. In the hot air circulation system, air is heated through a finned condenser and a finned waste heat exchanger to meet temperature requirements at different stages. This invention innovatively integrates the gas engine's waste heat with the coordinated control of the electric two-way valves to perform secondary heating of the air, achieving highly efficient heat energy utilization, significantly improving the system's heating performance, and greatly enhancing safety. Attached Figure Description

[0020] Figure 1 This is a flow chart of a gas engine-driven air source heat pump dryer unit according to the present invention.

[0021] 1. Gas engine 2. Compressor 3. Oil-gas separator 4-1. First finned condenser 4-2. Second finned condenser 5. Liquid receiver 6. Dryer filter 7. Liquid supply solenoid valve 8. Sight glass 9. Expansion tank 10. Thermal expansion valve 11. Gas filter 12. Finned evaporator 13. Gas-liquid separator 14. Antifreeze circulating pump 15. Flue gas heat exchanger 16. Internal circulation electric two-way valve 17. Waste heat electric two-way valve 18. Radiator electric two-way valve 19. Finned waste heat exchanger 20. Finned radiator heat exchanger 21. Sensible heat exchanger 22. Gas solenoid valve 23. Main fan 24. T-junction 25. Intensive drying oven 26. Dehumidifier fan 27. Fresh air valve 28. Fresh air unit 29. Exhaust damper Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] This invention is based on the following principle: The gas engine-driven air source heat pump dryer unit is primarily based on the reverse Carnot cycle. It uses natural gas as an energy supply, enabling the gas engine to drive the compressor and achieve the reverse Carnot cycle. This allows the refrigerant to circulate in the vapor compression heat pump system loop, absorbing heat energy from an external low-temperature heat source and releasing it into the drying medium through a heat exchanger. By utilizing natural gas as an energy supply, the gas engine-driven air source heat pump dryer unit significantly solves the problem of unstable regional voltage. Furthermore, the air source gas engine heat pump dryer unit can also use various other fuels such as petroleum gas, biogas, and methanol as its energy supply, greatly addressing the issue of unstable energy supply in different regions. Regarding energy utilization, the gas engine-driven air source heat pump dryer unit can also utilize the exhaust waste heat and cylinder liner waste heat from the gas engine, converting them into high-grade heat energy for secondary heating of the unit's air. This energy utilization method allows the air source heat pump dryer unit to efficiently complete the drying task even under cold conditions, greatly improving the unit's primary energy utilization rate and system heating COP.

[0024] like Figure 1 As shown, this utility model discloses a gas engine-driven air source heat pump dryer unit, which includes a gas engine system, a hot air circulation system, an evaporative compression heat pump system, and an antifreeze circulation system.

[0025] The gas engine system includes a natural gas pipeline, one end of which is connected to a natural gas supply source, and the other end is sequentially connected to a gas filter 11, a gas solenoid valve 22, and a gas engine 1. The output shaft of the gas engine 1 is connected to a compressor 2 via a transmission system. The compressor 2 is preferably an open-type compressor for transportation.

[0026] The operation method of the gas engine system includes the following steps:

[0027] The drive shaft of the gas engine 1 is connected to the output shaft of the compressor 2 via a belt, driving the compressor to perform work.

[0028] The hot air circulation system includes two finned waste heat exchangers 19. The exhaust ports of the two finned waste heat exchangers 19 are connected in sequence to the main fan 23, the dense drying room 25, the exhaust valve 29, the dehumidifying fan 26, the high-temperature channel of the sensible heat exchanger 21, the high-temperature air duct of the finned evaporator 12, the air inlet of the finned heat exchanger 20, and the low-temperature channel air inlet of the sensible heat exchanger 21 through a second pipeline. The exhaust ports of the low-temperature channels of the two sensible heat exchangers 21 are connected to the atmosphere. One end of each of the two third pipes is connected to the second pipe located between the exhaust vent and the dehumidification valve 29 of each dense drying room 25, and the other end is connected to the air inlet of a finned condenser 4 and a finned waste heat exchanger 19 in sequence; two fresh air pipes with one end connected to the atmosphere are connected to the fresh air fan 28 and the fresh air valve 27 in sequence, and the other end is connected to the air inlet of the first finned condenser 4-1 or the air inlet of the second finned condenser 4-2 in sequence.

[0029] The operation method of the hot air circulation system includes the following steps:

[0030] High-temperature, low-humidity air (typically 55℃-60℃, relative humidity 50%-60%RH) from two finned waste heat exchangers 19 enters the intensive curing barn 25 and exchanges heat and moisture with the tobacco leaves, becoming high-temperature, high-humidity air (typically 40℃-50℃, relative humidity 90%-100%RH). A small portion (5%-15% of the total exhaust air mass) of this high-temperature, high-humidity air then passes through exhaust damper 29 and enters two sensible heat exchangers 21, where it exchanges heat with the exhaust air from two finned heat exchangers 20, resulting in a first cooling of the high-temperature, high-humidity air. After this first cooling, the air enters the finned evaporator 12 and exchanges heat and moisture with the refrigerant for a second cooling. This second cooling process lowers the air temperature and simultaneously discharges condensate. Air passes through the finned heat exchanger 20 without heat exchange, then passes through two sensible heat exchangers 21 again, where it exchanges heat with the high-temperature, high-humidity air. The air is then discharged from the two sensible heat exchangers 21. Another portion of the high-temperature, high-humidity air discharged from the intensive drying chamber 25 (accounting for 85%-95% of the total exhaust air mass) mixes with the same volume of outdoor fresh air introduced by the fresh air fan 28. The air undergoes heat exchange with the refrigerant from the oil-gas separator 3 in the finned condenser 4 to achieve a primary temperature increase. Then, it undergoes heat exchange with the antifreeze from the gas engine 1 in the finned waste heat exchanger 19 to achieve a secondary temperature increase, bringing the air to the temperature and humidity standards for drying the material. The air is then sent into the intensive drying chamber 25 through the two main fans 23 to exchange heat and moisture with the tobacco leaves. The above operation is then repeated.

[0031] The evaporative compression heat pump system includes the gas engine 1, the exhaust port of the compressor 2 is connected to the inlet end of the oil-gas separator 3, and the oil return port of the oil-gas separator 3 is connected to the oil return port of the compressor 2 through the oil return pipe. The outlet of the oil-gas separator 3 is divided into two paths and connected to the inlet of the refrigerant channel of the first finned condenser 4-1 and the second finned condenser 4-2, respectively. The outlet of the refrigerant channel of the first finned condenser 4-1 and the second finned condenser 4-2 merges and is connected to the inlet pipe of the liquid storage tank 5. The outlet pipe of the liquid storage tank 5 is connected to the dryer filter 6 and the liquid supply solenoid valve 7 in sequence. The outlet B of the liquid supply solenoid valve 7 is divided into two paths. The outlet of each liquid supply solenoid valve 7 is connected to the sight glass 8, the thermal expansion valve 10 and the liquid phase pipeline of the finned evaporator 12 in sequence through the liquid supply solenoid valve outlet pipeline. The liquid phase pipelines of the two finned evaporators 12 merge and are connected to the inlet of the gas-liquid separator 13, the outlet of the gas-liquid separator 13 and the suction end of the compressor 2 in sequence.

[0032] The operation method of the evaporative compression heat pump system includes the following steps:

[0033] The compressor 2 compresses the low-pressure, high-temperature gaseous refrigerant from the finned evaporator 12, which has undergone gas-liquid separation in the gas-liquid separator 13, into a high-temperature, high-pressure gaseous refrigerant (60℃-70℃, 15bar-17bar). The compressed gaseous refrigerant first enters the oil-gas separator 3 through the compressor exhaust port to separate the gaseous refrigerant from the mixed refrigeration oil. Under the action of pressure difference, the refrigeration oil returns to the compressor 2 for recycling through the oil return pipe of the oil-gas separator 3. The high-temperature, high-pressure gaseous refrigerant discharged from the oil-gas separator 3 enters the first finned condenser 4-1 and the second finned condenser 4-2. It exchanges heat with the remaining exhaust air from the corresponding dense drying chamber 25 (bypassed by the exhaust valve) and outdoor air from the fresh air duct, forming a lower-temperature circulating hot air system. It then transforms into a medium-temperature, high-pressure (60℃-70℃, 15bar-17bar) liquid refrigerant, which enters the liquid storage tank 5. The liquid refrigerant is discharged from the liquid storage tank 5, passing sequentially through the dryer filter 6 and the liquid supply solenoid valve 7. It then splits into two paths, each flowing sequentially through the sight glass 8 and the thermal expansion valve 10, becoming a low-temperature, low-pressure (60℃-70℃, 15bar-17bar) liquid refrigerant. A two-phase gas-liquid refrigerant (5℃-15℃, 4bar-5bar) is introduced into a corresponding finned evaporator 12. It then exchanges heat with the circulating hot air discharged from a corresponding sensible heat exchanger 21, transferring heat to the low-temperature, low-pressure two-phase gas-liquid refrigerant. This causes the low-temperature, low-pressure two-phase gas-liquid refrigerant to become a low-temperature, low-pressure gaseous refrigerant (5℃-15℃, 4bar-5bar). The gaseous refrigerant discharged from the two finned evaporators 12 enters a gas-liquid separator 13, where the mixed liquid refrigerant is separated. The gaseous refrigerant is then drawn into the compressor 2 and compressed again to enter the next heating cycle.

[0034] The antifreeze circulation system includes the cylinder liner outlet of the gas engine 1, port A of the three-way valve 24, port B of the three-way valve 24, the internal circulation electric two-way valve 16, the antifreeze circulating water pump 14, the coolant passage of the flue gas heat exchanger 15, and the coolant inlet of the gas engine 1, all connected sequentially through a first pipeline. The exhaust port of the gas engine 1 is connected to the flue gas passage inlet of the flue gas heat exchanger 15, and the exhaust port of the flue gas heat exchanger 15 is open to the atmosphere. Port C of the three-way valve 24 is divided into two three-way branches. The first three-way branch is connected sequentially to the waste heat electric two-way valve 17, the liquid phase pipelines of the two finned waste heat heat exchangers 19, and the first pipeline located between the antifreeze circulating water pump 14 and the internal circulation electric two-way valve 16. Preferably, the outlet of an expansion tank 9 is connected to the first three-way branch at the outlet of the liquid phase pipeline of the two finned waste heat heat exchangers 19. The second three-way branch is connected in sequence to the heat dissipation electric two-way valve 18, the liquid phase pipelines of the two finned heat exchangers 20, and the first pipeline located between the antifreeze circulating water pump 14 and the internal circulation electric two-way valve 16.

[0035] The operation method of the aforementioned antifreeze circulation system includes the following steps:

[0036] Step 1: The antifreeze is sent to the flue gas heat exchanger 15 by the antifreeze circulating water pump 14 to exchange heat with the exhaust gas of the gas engine for the first time to raise the temperature. After the first heat exchange, the antifreeze exchanges heat with the waste heat in the cylinder liner of the gas engine 1 for the second time to raise the temperature. After the second heat exchange, the antifreeze flows through the three-way valve 24. According to the actual heat exchange requirements, the flow is distributed and controlled by the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18, and then enters the finned waste heat heat exchanger 19 and the finned heat dissipation heat exchanger 20 to exchange heat with the air to lower the temperature.

[0037] Step 2: Repeat Step 1 to enter the next heating cycle.

[0038] Specifically, the heat exchange process between the antifreeze and the exhaust gas of the gas engine in step one is as follows:

[0039] The high-temperature flue gas (400℃-600℃) discharged from the gas engine 1 enters the flue gas heat exchanger 15. At the same time, antifreeze (75℃-85℃) is pumped into the flue gas heat exchanger 15 by the antifreeze circulating water pump 14 to exchange heat with the high-temperature flue gas. The heat in the high-temperature flue gas is transferred to the antifreeze, which then enters the gas engine 1. The flue gas is discharged from the unit through the exhaust pipe of the flue gas heat exchanger 15.

[0040] The process of the antifreeze undergoing a second heat exchange and warming up with the cylinder liner of the gas engine 1 after the first heat exchange is as follows:

[0041] The first step is to rapidly heat up the antifreeze: close the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18, open the internal circulation electric two-way valve 16, and the antifreeze flows from the gas engine 1 through the three-way valve 24 and the internal circulation electric two-way valve 16 back to the antifreeze circulating water pump 14, then enters the flue gas heat exchanger 15 to exchange heat with the engine exhaust, and then exchanges heat with the waste heat in the gas engine cylinder liner to rapidly increase the temperature. If the antifreeze temperature reaches the set value of the gas engine coolant circulation temperature, the second step is executed; otherwise, the first step is repeated.

[0042] The second step involves a secondary heating process for the air: the internal circulation electric two-way valve 16 and the cooling electric two-way valve 18 are closed, and the waste heat electric two-way valve 17 is opened. The antifreeze flows from the gas engine 1 through the three-way valve 24 and the waste heat electric two-way valve 17, and enters the finned waste heat exchanger 19 in two paths to exchange heat with the circulating air from the condenser 4, thus raising the temperature of the circulating air. Then the antifreeze merges back and returns to the antifreeze circulating water pump 14, and then enters the flue gas heat exchanger 15 to exchange heat with the engine exhaust, and then exchanges heat with the waste heat in the gas engine cylinder liner. After the heat exchange is completed, the next heating cycle is performed to ensure that the air meets the requirements for outlet temperature and humidity.

[0043] According to the actual heat exchange requirements, the specific process of flow distribution control through the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18 is as follows: the internal circulation electric two-way valve 16 is closed, and the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18 are opened, with the total opening degree of the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18 being 100%; the antifreeze flows from the gas engine 1 through the three-way valve 24, and then the flow is controlled by the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18, and then enters the finned waste heat heat exchanger 19 to exchange heat and cool down with the circulating air from the condenser 4, and at the same time enters the finned heat dissipation heat exchanger 20 to exchange heat and cool down with the exhaust air from the finned evaporator 12. After completing the heat exchange, the antifreeze is then completely returned to the antifreeze circulating water pump 14, and then enters the flue gas heat exchanger 15 to exchange heat with the engine exhaust, and then exchanges heat with the waste heat in the gas engine cylinder liner to carry out the next round of heating cycle. Preferably, a large portion of the antifreeze, accounting for 70%-80% of the total antifreeze mass flow rate, is sent to the finned waste heat exchanger 19, while a smaller portion, accounting for 20%-30% of the total antifreeze mass flow rate, is sent to the finned heat exchanger 20 to meet the unit's heat dissipation and the temperature and humidity requirements of the circulating air outlet.

[0044] In the specific process of flow distribution control through the waste heat electric two-way valve 17 and the heat dissipation electric two-way valve 18, preferably, when the gas engine is running at a high speed (1800rpm-2000rpm), the antifreeze discharged from the gas engine 1 expands and the pressure increases. After completing the heat exchange, part of the antifreeze returns to the antifreeze circulating water pump 14, another part is pressed into the expansion tank 9, and the remaining part returns to the antifreeze circulating water pump 14 and the flue gas heat exchanger 15, thereby relieving pressure and avoiding damage to other components.

[0045] Preferably, the antifreeze automatic replenishment process is as follows: During unit operation, antifreeze beyond the system's operational requirements is pumped into the expansion tank 9. Throughout the unit's operating cycle, the system's antifreeze is automatically replenished via pipelines. When the gas engine 1 shuts down, the temperature drops, causing the antifreeze in the circulation system to contract, resulting in negative pressure within the system. The antifreeze in the expansion tank 9 is then pumped by the antifreeze circulation pump 14 through the flue gas heat exchanger 15 into the gas engine cylinder liner heat exchanger to maintain pressure balance.

[0046] The above-described specific embodiments are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of this utility model without departing from the spirit and scope of the claims, and these modifications are all protected by this utility model.

Claims

1. A gas engine-driven air source heat pump dryer unit, comprising a gas engine system, a hot air circulation system, an evaporative compression heat pump system, and an antifreeze circulation system; wherein the gas engine system comprises a gas engine and a compressor; characterized in that: The hot air circulation system includes two finned waste heat exchangers (19). The exhaust ports of the two finned waste heat exchangers are connected in sequence via a second pipeline to the main fan (23), the intensive drying oven (25), the exhaust valve (29), the dehumidifying fan (26), the high-temperature channel of the sensible heat exchanger (21), the high-temperature air duct of the finned evaporator (12), the air inlet of the finned heat exchanger (20), and the low-temperature channel air inlet of the sensible heat exchanger (21). The exhaust ports of the low-temperature channels of the two sensible heat exchangers (21) are connected to the main fan (23), the intensive drying oven (25), the exhaust valve (29), the dehumidifying fan (26), the high-temperature channel of the sensible heat exchanger (21), the high-temperature air duct of the finned evaporator (12), the air inlet of the finned heat exchanger (20), and the low-temperature channel air inlet of the sensible heat exchanger (21). The two third pipes are connected to the atmosphere. One end of each third pipe is connected to the second pipe between the exhaust port and the exhaust valve (29) of each dense drying room (25), and the other end is connected to the air inlet of a finned condenser (4) and a finned waste heat exchanger (19) in sequence. Two fresh air pipes with one end connected to the atmosphere are connected to the fresh air fan (28) and the fresh air valve (27) in sequence, and the other end is connected to the air inlet of the first finned condenser (4-1) or the air inlet of the second finned condenser (4-2) in sequence. The evaporative compression heat pump system includes the gas engine. The exhaust port of the compressor (2) is connected to the inlet end of the oil-gas separator (3). The oil return port of the oil-gas separator (3) is connected to the oil return port of the compressor via an oil return pipe. The outlet of the oil-gas separator (3) is split into two paths and connected to the inlet ends of the refrigerant passages of the first finned condenser (4-1) and the second finned condenser (4-2) respectively. The outlet ends of the refrigerant passages of the first finned condenser (4-1) and the second finned condenser (4-2) merge and then connect to the storage tank. The liquid tank (5) is connected to the liquid inlet pipe, and the liquid outlet pipe of the storage tank is connected to the dryer filter (6) and the liquid supply solenoid valve (7) in sequence. The outlet end B of the liquid supply solenoid valve is divided into two paths. The outlet end of each liquid supply solenoid valve (7) is connected to the sight glass (8), the thermal expansion valve (10) and the liquid phase pipeline of the finned evaporator (12) in sequence through the liquid supply solenoid valve outlet pipeline. After the liquid phase pipelines of the two finned evaporators merge, they are connected to the inlet end of the gas-liquid separator (13), the outlet end of the gas-liquid separator (13) and the suction end of the compressor (2) in sequence. The antifreeze circulation system includes the cylinder liner outlet of the gas engine (1), port A of the three-way valve (24), port B of the three-way valve, internal circulation electric two-way valve (16), antifreeze circulating water pump (14), coolant passage of flue gas heat exchanger (15), and coolant inlet of the gas engine, all connected sequentially through the first pipeline; the exhaust port of the gas engine is connected to the flue gas passage inlet of the flue gas heat exchanger, and the exhaust port of the flue gas heat exchanger (15) is connected to the atmosphere, and port C of the three-way valve... It is divided into two three-way branches. The first three-way branch is connected in sequence to the waste heat electric two-way valve (17), the liquid phase pipeline of the two finned waste heat heat exchangers (19), and the first pipeline located between the antifreeze circulating water pump (14) and the internal circulation electric two-way valve (16). The second three-way branch is connected in sequence to the heat dissipation electric two-way valve (18), the liquid phase pipeline of the two finned heat dissipation heat exchangers (20), and the first pipeline located between the antifreeze circulating water pump (14) and the internal circulation electric two-way valve (16).

2. The gas engine-driven air source heat pump dryer unit according to claim 1, characterized in that: The compressor is an open-type compressor for transportation.

3. The gas engine-driven air source heat pump dryer unit according to claim 1 or 2, characterized in that: The outlet of an expansion tank (9) is connected to the first tee branch at the liquid phase pipeline outlet of two finned waste heat exchangers (19).

4. The gas engine-driven air source heat pump dryer unit according to claim 1 or 2, characterized in that: The gas engine system includes a natural gas pipeline. One end of the natural gas pipeline is connected to a natural gas supply source, and the other end is connected in sequence to a gas filter (11), a gas solenoid valve (22), and a gas engine (1). The output shaft of the gas engine is connected to a compressor (2) through a transmission system.

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