Conductive drying system using a dual heat pump combination to supply heat to a dryer and its process

Abstract

The present invention discloses a conduction drying system and a process thereof for supplying heat to a dryer using a dual heat pump combination, which belongs to the field of energy conservation and environmental protection, and includes a dryer, a mechanical compression high-temperature heat pump system, a steam compression MVR heat pump system, a steam boiler and a steam quantity regulating device; the mechanical compression high-temperature heat pump system recovers all the heat of the drying tail gas discharged by the dryer, and returns to the dryer as a carrier gas for continuous circulation after cooling, dehumidification and then heating without venting; the steam compression MVR heat pump system recovers condensed water and the surplus heat of the mechanical compression high-temperature heat pump system, generates steam and returns to the dryer to continue heating the material; the steam boiler assists in providing steam to the dryer; the steam quantity regulating device is connected to the dryer through a steam input pipeline. The present invention can save a large amount of heating steam originally provided entirely by a steam boiler, and use it as a heat source for the dryer and a heat source for heating the carrier air, which not only saves energy but also reduces pollutant emissions, and has considerable economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and environmental protection, and in particular to a conduction drying system and its process that uses a dual heat pump combination to supply heat to a dryer. Background Art

[0002] The drying process involves a wide range of fields in the national economy, such as agriculture, food, chemical industry, pottery, medicine, mineral processing, pulp and paper making, wood processing and other industries. Almost all production processes use the drying process. However, the traditional drying operation is a high-energy-consuming process. The energy consumed by drying in China each year accounts for about 12% of the total energy consumption of the national economy. At the same time, the traditional drying process is also one of the factors causing environmental pollution. To address energy and environmental issues and achieve the sustainable development of the national economy, energy conservation and environmental protection in the drying process are becoming increasingly important. In particular, improving the energy use efficiency and reducing pollution emissions in the energy industry to achieve intensive and efficient use of energy are the goals pursued by the current drying industry.

[0003] A dryer is a mechanical device that uses heat energy to reduce the moisture content of materials and is used for drying objects. Conduction dryers usually include double paddle dryers, disk dryers, rake dryers, etc. The dryer vaporizes and escapes the moisture in the material by heating to obtain solid materials with a specified moisture content. The conduction dryer is also called an indirect dryer. It uses the conduction method to transfer heat from the heat source through the metal partition wall to the wet material, and the generated moisture is carried away by the carrier gas air. The traditional method is to directly discharge the moisture-carrying air, which will cause certain pollution.

[0004] Therefore, it is necessary to develop a drying system and its process that can save conventional energy and reduce pollutant emissions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a conduction drying system and its process that uses a dual heat pump combination to supply heat to a dryer, which can save a large amount of heating steam that was originally provided entirely by a steam boiler and be used as the heat source for the dryer and the heat source for heating the carrier gas air.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A conductive drying system that uses a dual heat pump combination to supply heat to a dryer, comprising a dryer, a mechanical compression high-temperature heat pump system, a steam compression MVR heat pump system, a steam boiler, a steam volume regulating device, and various connecting pipelines; the mechanical compression high-temperature heat pump system fully recovers the heat of the dry exhaust gas discharged from the dryer, cools, dehumidifies, and then reheats it, and returns it as a carrier gas to the dryer for continuous circulation without venting; the steam compression MVR heat pump system recovers the condensed water and the surplus heat of the mechanical compression high-temperature heat pump system, generates heating steam and returns it to the dryer to continue heating the wet material; the steam volume regulating device is connected to the dryer through a steam input pipeline; during the drying process, the steam boiler supplies heating steam to the dryer through the steam volume regulating device as an auxiliary.

[0008] A further improvement of the technical solution of the present invention lies in that: the mechanical compression high-temperature heat pump system includes a dry dust collector, an evaporator, a fan, a condenser, a compressor, a reversing valve, an evaporation heat exchanger, a liquid receiver, and an expansion valve; the gas-phase inlet of the dry dust collector is connected to the gas-phase outlet of the dryer, and the gas-phase outlet of the dry dust collector is connected to the gas-phase inlet of the evaporator; the gas-phase outlet of the evaporator is connected to the inlet of the fan, and the liquid-phase outlet of the evaporator is connected to the inlet of the condensed water flash tank in the steam compression MVR heat pump system; the working medium inlet of the evaporator is connected to the outlet of the liquid receiver through the expansion valve, and the working medium outlet of the evaporator is connected to the inlet of the compressor; the outlet of the fan is connected to the gas-phase inlet of the condenser; the gas-phase outlet of the condenser is connected to the carrier gas inlet of the dryer; the working medium inlet of the condenser is connected to the outlet of the compressor through the reversing valve, and the working medium outlet of the condenser is connected to the inlet of the liquid receiver; the working medium inlet of the evaporation heat exchanger is connected to the outlet of the compressor through the reversing valve, and the working medium outlet of the evaporation heat exchanger is connected to the inlet of the liquid receiver; the liquid-phase inlet of the evaporation heat exchanger is connected to the upper outlet of the condensed water flash tank in the steam compression MVR heat pump system, and the steam outlet of the evaporation heat exchanger is connected to the steam inlet of the MVR steam compressor in the steam compression MVR heat pump system.

[0009] A further improvement of the technical solution of the present invention lies in that: the temperature of the dry air coming out of the gas-phase outlet of the condenser is 90 - 100 °C.

[0010] A further improvement of the technical solution of the present invention lies in that: the steam compression type MVR heat pump system includes a condensate flash tank, an MVR steam compressor, a condensate pump, a steam trap, and an MVR compressor control device; the inlet of the condensate flash tank is respectively connected to the outlet of the steam trap and the liquid phase outlet of the evaporator in the mechanical compression high-temperature heat pump system; the steam trap is arranged on the pipeline at the condensate outlet end of the dryer; the upper outlet of the condensate flash tank is connected to the vapor / liquid inlet of the evaporation heat exchanger in the mechanical compression high-temperature heat pump system; the steam inlet of the MVR steam compressor is connected to the steam outlet of the evaporation heat exchanger in the mechanical compression high-temperature heat pump system, and the steam outlet of the MVR steam compressor is connected to the steam inlet of the steam quantity regulating device; the condensate pump is connected to the lower outlet of the condensate flash tank; the MVR compressor control device is controlled by a PLC and controls the dynamic parameters of the second heating steam generated by the MVR steam compressor according to the flow rate, temperature, and pressure parameters of the evaporation heat exchanger.

[0011] A further improvement of the technical solution of the present invention lies in that: the steam outlet temperature of the MVR steam compressor is 110 - 160 °C.

[0012] A further improvement of the technical solution of the present invention lies in that: the condensate in the condensate flash tank is flashed into low-pressure steam at about 90 °C through the evaporation heat exchanger.

[0013] A further improvement of the technical solution of the present invention lies in that: the steam quantity regulating device is controlled by a PLC to obtain the flow rate parameter of the first heating steam from the steam boiler in real time; the steam quantity regulating device includes a display device, an input device, a processing device, and a steam parameter sensor and a steam flow controller arranged on the steam pipeline.

[0014] A further improvement of the technical solution of the present invention lies in that: the steam pressure output by the steam quantity regulating device is 0.2 - 0.4 MPa, and the steam temperature is 110 - 160 °C.

[0015] A further improvement of the technical solution of the present invention lies in that: the dryer adopts a conduction dryer, which is any one of a double paddle dryer, a disk dryer, and a rake dryer.

[0016] A conduction drying process using a double heat pump combination to supply heat to a dryer is as follows:

[0017] The first heating steam from the steam boiler is adjusted by the steam quantity regulating device and then enters the dryer to dry the wet material, and the dried dry material is discharged from the bottom material outlet of the dryer through a discharge valve.

[0018] The dried tail gas discharged from the dryer is filtered by a dry dust removal filter, then enters the evaporator to cool down and dehumidify, and then is sent into the condenser by a fan to be heated up and returned to the dryer as a carrier gas for continuous recycling without venting; the material filtered by the dry dust removal filter is discharged from the bottom material outlet of the dry dust removal filter.

[0019] The condensed water from the outlet of the steam trap and the liquid phase outlet of the evaporator enters the condensed water flash tank. The condensed water in the condensed water flash tank is flashed into low-pressure steam at about 90 °C through an evaporation heat exchanger. The low-pressure steam enters the MVR steam compressor to be pressurized into the second heating steam required by the dryer. The second heating steam converges with the first heating steam and then enters the steam flow regulating device. The heating steam regulated by the steam flow regulating device heats the wet material in the dryer; the surplus condensed water in the condensed water flash tank is pumped away by a condensate pump.

[0020] The MVR compressor control device controls the dynamic parameters of the MVR steam compressor based on the flow rate, temperature, and pressure parameters of the evaporation heat exchanger. The steam flow regulating device real-time obtains the flow rate parameter of the first heating steam from the steam boiler and adjusts the flow rate parameter of the first heating steam of the steam boiler according to the dynamic parameters of the second heating steam generated by the MVR steam compressor obtained by the MVR compressor control device; ensure that the first heating steam from the steam boiler is used when the second heating steam generated by the MVR steam compressor is used up.

[0021] The working medium enters the evaporator from the liquid receiver through the expansion valve, and then is respectively sent into the condenser and the evaporation heat exchanger through the compressor and the reversing valve, and then all flow into the liquid receiver.

[0022] Due to the adoption of the above technical solutions, the technical progress achieved by the present invention is:

[0023] 1. The present invention adopts an MVR steam compression heat pump to return the recovered waste heat steam to the dryer to transfer heat to the wet material through the partition wall for conduction drying. The moisture of the dried material is all recovered by the mechanical compression heat pump from the tail gas heat of the dryer, cooled down, dehumidified and then heated up and returned to the dryer as a carrier gas for continuous recycling without venting, which not only saves conventional energy but also reduces pollutant emissions.

[0024] 2. The system heat pump in the present invention uses the principle of reverse Carnot cycle to absorb heat from the surrounding low-temperature medium, and converts a certain amount of low-temperature thermal energy into higher-temperature thermal energy through the heat pump system to increase the temperature of the carrier gas and improve the moisture-carrying capacity, thereby promoting the drying of the material. The heat pump drying only consumes the electric energy used when the compressor works, and can obtain energy from the dried tail gas. At the same time, the electric energy consumed by the compressor is also converted into heat energy and used for drying, thereby improving the energy efficiency ratio.

[0025] 3. The heating steam converted from the surplus heat recovered from the drying exhaust gas in the present invention can meet two-thirds of the steam consumption of the dryer. During the drying process, the steam boiler is used as an auxiliary steam supply device, greatly saving the energy consumption of the steam boiler. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of a conduction drying system using a double heat pump combination to supply heat to the drying system provided in the embodiment of the present invention.

[0028] Among them, 1. Dryer; 2. Dry dust filter; 3. Evaporator; 4. Fan; 5. Condenser; 6. Compressor; 7. Reversing valve; 8. Evaporation heat exchanger; 9. Liquid receiver; 10. Expansion valve; 11. Discharge valve; 12. Steam trap; 13. Condensate flash tank; 14. MVR steam compressor; 15. Condensate pump. Detailed Embodiments

[0029] It should be noted that the terms "including" and "having" and any variations thereof in the description and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] The following will further describe the present invention in detail with reference to the drawings and embodiments:

[0031] As Figure 1As shown in the figure, a conduction drying system that uses a dual heat pump combination to supply heat to a dryer is characterized by including a dryer 1, a mechanical compression high-temperature heat pump system, a steam compression MVR heat pump system, a steam boiler, a steam volume regulating device, and various connecting pipelines; the mechanical compression high-temperature heat pump system recovers all the heat of the dry exhaust gas discharged from the dryer 1, cools, dehumidifies, and then reheats it, and returns it as a carrier gas to the dryer 1 for continuous circulation without venting; the steam compression MVR heat pump system recovers the condensate water and the surplus heat of the mechanical compression high-temperature heat pump system, generates heating steam and returns it to the dryer 1 to continue heating the wet material; the steam volume regulating device is connected to the dryer 1 through a steam input pipeline; during the drying process, the steam boiler supplies heating steam to the dryer 1 through the steam volume regulating device as an auxiliary.

[0032] The operating parameters of the mechanical compression high-temperature heat pump system control the parameters of the MVR steam compressor 14 of the steam compression MVR heat pump system, and the MVR steam compressor 14 in turn controls the size of the steam volume introduced into the dryer. They are all completed by PLC programming control.

[0033] Further, the mechanical compression high-temperature heat pump system includes a dry dust collector 2, an evaporator 3, a fan 4, a condenser 5, a compressor 6, a reversing valve 7, an evaporation heat exchanger 8, a liquid receiver 9, and an expansion valve 10; the gas-phase inlet of the dry dust collector 2 is connected to the gas-phase outlet of the dryer 1, and the gas-phase outlet of the dry dust collector 2 is connected to the gas-phase inlet of the evaporator 3; the gas-phase outlet of the evaporator 3 is connected to the inlet of the fan 4, and the liquid-phase outlet of the evaporator 3 is connected to the inlet of the condensate flash tank 13 in the steam compression MVR heat pump system; the working medium inlet of the evaporator 3 is connected to the outlet of the liquid receiver 9 through the expansion valve 10, and the working medium outlet of the evaporator 3 is connected to the inlet of the compressor 6; the outlet of the fan 4 is connected to the gas-phase inlet of the condenser 5; the gas-phase outlet of the condenser 5 is connected to the carrier gas inlet of the dryer 1; the working medium inlet of the condenser 5 is connected to the outlet of the compressor 6 through the reversing valve 7, and the working medium outlet of the condenser 5 is connected to the inlet of the liquid receiver 9; the working medium inlet of the evaporation heat exchanger 8 is connected to the outlet of the compressor 6 through the reversing valve 7, and the working medium outlet of the evaporation heat exchanger 8 is connected to the inlet of the liquid receiver 9; the liquid-phase inlet of the evaporation heat exchanger 8 is connected to the upper outlet of the condensate flash tank 13 in the steam compression MVR heat pump system, and the steam outlet of the evaporation heat exchanger 8 is connected to the steam inlet of the MVR steam compressor 14 in the steam compression MVR heat pump system.

[0034] Further, the temperature of the dry air coming out of the gas-phase outlet of the condenser 5 is 90 - 100 °C.

[0035] Further, the vapor compression MVR heat pump system includes a condensate flash tank 13, an MVR steam compressor 14, a condensate pump 15, a steam trap 12, and an MVR compressor control device; the inlet of the condensate flash tank 13 is respectively connected to the outlet of the steam trap 12 and the liquid-phase outlet of the evaporator 3 in the mechanical compression high-temperature heat pump system; the steam trap 12 is arranged on the pipeline at the condensate outlet end of the dryer 1; the upper outlet of the condensate flash tank 13 is connected to the vapor / liquid-phase inlet of the evaporation heat exchanger 8 in the mechanical compression high-temperature heat pump system; the steam inlet of the MVR steam compressor 14 is connected to the steam outlet of the evaporation heat exchanger 8 in the mechanical compression high-temperature heat pump system, and the steam outlet of the MVR steam compressor 14 is connected to the steam inlet of the steam quantity regulating device; the condensate pump 15 is connected to the lower outlet of the condensate flash tank 13; the MVR compressor control device is controlled by PLC and controls the dynamic parameters of the second heating steam generated by the MVR steam compressor 14 according to the flow rate, temperature, and pressure parameters of the evaporation heat exchanger 8.

[0036] Further, the steam outlet temperature of the MVR steam compressor 14 is 110 - 160 °C.

[0037] Further, the condensate in the condensate flash tank 13 is flashed into low-pressure steam at about 90 °C through the evaporation heat exchanger 8.

[0038] Further, the steam quantity regulating device is controlled by PLC to obtain the flow rate parameter of the first heating steam from the steam boiler in real time; the steam quantity regulating device includes a display device, an input device, a processing device, a steam parameter sensor, and a steam flow controller arranged on the steam pipeline. The setting of the steam quantity regulating device can observe the steam temperature and steam pressure of the first heating steam output by the steam boiler in real time.

[0039] Further, the steam pressure output by the steam quantity regulating device is 0.2 - 0.4 MPa, and the steam temperature is 110 - 160 °C.

[0040] Further, the dryer 1 adopts a conductive dryer, which can be any one of a double paddle dryer, a disk dryer, and a rake dryer. The evaporation heat exchanger 8 can adopt any one of falling film or other types.

[0041] A conductive drying process using a double heat pump combination to supply heat to a dryer is as follows:

[0042] The first heating steam from the steam boiler is adjusted by the steam quantity regulating device and then enters the dryer 1 to dry the wet material. The dried dry material is discharged from the bottom material outlet of the dryer 1 through the discharge valve 11.

[0043] The dried exhaust gas discharged from the dryer 1 is filtered by the dry dust removal filter 2, then enters the evaporator 3 to cool down and dehumidify, and then is sent into the condenser 5 by the fan 4 to increase the temperature and then returned to the dryer 1 as the carrier gas for continuous recycling without venting; the material filtered by the dry dust removal filter 2 is discharged from the bottom material outlet of the dry dust removal filter 2;

[0044] The condensed water from the outlet of the steam trap 12 and the liquid phase outlet of the evaporator 3 enters the condensed water flash tank 13. The condensed water in the condensed water flash tank 13 is flashed into low-pressure steam at about 90 °C through the evaporation heat exchanger 8. The low-pressure steam enters the MVR steam compressor 14 and is pressurized into the second heating steam required by the dryer 1. The second heating steam converges with the first heating steam and then enters the steam flow regulating device. The heating steam after being regulated by the steam flow regulating device heats the wet material in the dryer 1; the surplus condensed water in the condensed water flash tank 13 is pumped away by the condensate pump 15;

[0045] The MVR compressor control device controls the dynamic parameters of the MVR steam compressor 14 based on the flow rate, temperature, and pressure parameters of the evaporation heat exchanger 8. The steam flow regulating device obtains the flow rate parameter of the first heating steam from the steam boiler in real time, and adjusts the flow rate parameter of the first heating steam of the steam boiler according to the dynamic parameters of the second heating steam generated by the MVR steam compressor 14 obtained by the MVR compressor control device; ensure that the first heating steam from the steam boiler is used when the second heating steam generated by the MVR steam compressor 14 is used up;

[0046] Specifically, according to the parameters of the material to be dried (wet material) and the feeding rate of the material, calculate the heat consumption value per unit time during the material drying process to revise the PLC programming control parameters of the steam flow regulating device and the MVR compressor control device. After all the second heating steam generated by the MVR steam compressor 14 is used up, and then the first heating steam supplied by the steam boiler is used as a supplementary steam source to make up, the heating steam is output to the dryer 1 to make the total heat supply value meet the heat consumption value in the conduction dryer.

[0047] The working medium enters the evaporator 3 from the liquid receiver 9 through the expansion valve 10, and then is respectively injected into the condenser 5 and the evaporation heat exchanger 8 through the compressor 6 and the reversing valve 7, and then all flow into the liquid receiver 9. The working medium can be selected according to the actual working conditions.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A conduction drying system that uses a dual heat pump combination to supply heat to a dryer, characterized in that, it includes a dryer (1), a mechanical compression high-temperature heat pump system, a steam compression MVR heat pump system, a steam boiler, a steam quantity regulating device and each connecting pipeline; the mechanical compression high-temperature heat pump system recovers all the heat of the dry exhaust gas discharged from the dryer (1), cools, dehumidifies and then reheats it and returns it to the dryer (1) as a carrier gas for continuous circulation without venting; the steam compression MVR heat pump system recovers the condensed water and the surplus heat of the mechanical compression high-temperature heat pump system, generates heating steam and returns it to the dryer (1) to continue heating the wet material; the steam quantity regulating device is connected to the dryer (1) through a steam input pipeline; during the drying process, the steam boiler supplies heating steam to the dryer (1) through the steam quantity regulating device for assistance; the mechanical compression high-temperature heat pump system includes a dry dust collector (2), an evaporator (3), a fan (4), a condenser (5), a compressor (6), a reversing valve (7), an evaporation heat exchanger (8), a liquid receiver (9) and an expansion valve (10); the gas-phase inlet of the dry dust collector (2) is connected to the gas-phase outlet of the dryer (1), and the gas-phase outlet of the dry dust collector (2) is connected to the gas-phase inlet of the evaporator (3); the gas-phase outlet of the evaporator (3) is connected to the inlet of the fan (4), and the liquid-phase outlet of the evaporator (3) is connected to the inlet of the condensed water flash tank (13) in the steam compression MVR heat pump system; the working medium inlet of the evaporator (3) is connected to the outlet of the liquid receiver (9) through the expansion valve (10), and the working medium outlet of the evaporator (3) is connected to the inlet of the compressor (6); the outlet of the fan (4) is connected to the gas-phase inlet of the condenser (5); the gas-phase outlet of the condenser (5) is connected to the carrier gas inlet of the dryer (1); the working medium inlet of the condenser (5) is connected to the outlet of the compressor (6) through the reversing valve (7), and the working medium outlet of the condenser (5) is connected to the inlet of the liquid receiver (9); the working medium inlet of the evaporation heat exchanger (8) is connected to the outlet of the compressor (6) through the reversing valve (7), and the working medium outlet of the evaporation heat exchanger (8) is connected to the inlet of the liquid receiver (9); the vapor / liquid inlet of the evaporation heat exchanger (8) is connected to the upper outlet of the condensed water flash tank (13) in the steam compression MVR heat pump system, and the steam outlet of the evaporation heat exchanger (8) is connected to the steam inlet of the MVR steam compressor (14) in the steam compression MVR heat pump system.

2. The conduction drying system that uses a dual heat pump combination to supply heat to a dryer according to claim 1, characterized in that, the dry air temperature coming out of the gas-phase outlet of the condenser (5) is 90 - 100 °C.

3. The conduction drying system that uses a dual heat pump combination to supply heat to a dryer according to claim 1, characterized in that, The steam compression MVR heat pump system includes a condensate flash tank (13), an MVR steam compressor (14), a condensate pump (15), a steam trap (12), and an MVR compressor control device; the inlet of the condensate flash tank (13) is respectively connected to the outlet of the steam trap (12) and the liquid phase outlet of the evaporator (3) in the mechanical compression high-temperature heat pump system; the steam trap (12) is arranged on the pipeline at the condensate outlet end of the dryer (1); the upper outlet of the condensate flash tank (13) is connected to the liquid phase inlet of the evaporation heat exchanger (8) in the mechanical compression high-temperature heat pump system; the steam inlet of the MVR steam compressor (14) is connected to the steam outlet of the evaporation heat exchanger (8) in the mechanical compression high-temperature heat pump system, and the steam outlet of the MVR steam compressor (14) is connected to the steam inlet of the steam quantity regulating device; the condensate pump (15) is connected to the lower outlet of the condensate flash tank (13); the MVR compressor control device is controlled by a PLC and controls the dynamic parameters of the second heating steam generated by the MVR steam compressor (14) according to the flow rate, temperature, and pressure parameters of the evaporation heat exchanger (8).

4. A conduction drying system using a dual heat pump combination to supply heat to a dryer according to claim 3, characterized in that, the steam outlet temperature of the MVR steam compressor (14) is 110 - 160 °C.

5. A conduction drying system using a dual heat pump combination to supply heat to a dryer according to claim 3, characterized in that, the condensate in the condensate flash tank (13) is flashed into low-pressure steam at about 90 °C through the evaporation heat exchanger (8).

6. A conduction drying system using a dual heat pump combination to supply heat to a dryer according to claim 1, characterized in that, the steam quantity regulating device is controlled by a PLC to obtain the flow rate parameter of the first heating steam from the steam boiler in real time; the steam quantity regulating device includes a display device, an input device, a processing device, a steam parameter sensor, and a steam flow controller arranged on the steam pipeline.

7. A conduction drying system using a dual heat pump combination to supply heat to a dryer according to claim 1, characterized in that, the steam pressure output by the steam quantity regulating device is 0.2 - 0.4 MPa, and the steam temperature is 110 - 160 °C.

8. A conduction drying system using a dual heat pump combination to supply heat to a dryer according to claim 1, characterized in that, the dryer (1) uses a conduction dryer, which is any one of a double paddle dryer, a disk dryer, and a rake dryer.

9. A conduction drying process using a dual heat pump combination to supply heat to a dryer, using the conduction drying system using a dual heat pump combination to supply heat to a dryer according to any one of claims 1 - 8, characterized in that, the process is as follows: The first heating steam from the steam boiler is adjusted by the steam quantity regulating device and then enters the dryer (1) to dry the wet material, and the dried dry material is discharged from the bottom material outlet of the dryer (1) through the discharge valve (11). The dried tail gas discharged from the dryer (1) is filtered by the dry dust removal filter (2), then enters the evaporator (3) for cooling and dehumidification, and then is sent into the condenser (5) by the fan (4) for temperature increase and returned to the dryer (1) as the carrier gas for continuous recycling without venting; the material filtered by the dry dust removal filter (2) of the dried tail gas is discharged from the bottom material outlet of the dry dust removal filter (2). The condensed water from the outlet of the steam trap (12) and the liquid phase outlet of the evaporator (3) enters the condensed water flash tank (13). The condensed water in the condensed water flash tank (13) is flashed into low-pressure steam at about 90 °C through the evaporation heat exchanger (8). The low-pressure steam enters the MVR steam compressor (14) to be pressurized into the second heating steam required by the dryer (1). The second heating steam is combined with the first heating steam and then enters the steam flow regulating device. The heating steam regulated by the steam flow regulating device heats the wet material in the dryer (1); the surplus condensed water in the condensed water flash tank (13) is pumped away by the condensate pump (15). The MVR compressor control device controls the dynamic parameters of the MVR steam compressor (14) according to the flow, temperature, and pressure parameters of the evaporation heat exchanger (8). The steam flow regulating device obtains the flow parameter of the first heating steam from the steam boiler in real time and adjusts the flow parameter of the first heating steam of the steam boiler according to the dynamic parameter of the second heating steam generated by the MVR steam compressor (14) obtained by the MVR compressor control device; ensure that the first heating steam from the steam boiler is used when the second heating steam generated by the MVR steam compressor (14) is used up. The working medium enters the evaporator (3) from the liquid receiver (9) through the expansion valve (10), and then is respectively injected into the condenser (5) and the evaporation heat exchanger (8) by the compressor (6) through the reversing valve (7), and then both flow into the liquid receiver (9).

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