Heating and drying system

Abstract

The invention discloses a heating and drying system in the technical field of industrial waste gas waste heat recovery. The heating and drying system comprises a waste gas waste heat cascade recovery module and a waste heat utilization coupling natural gas heating and drying module. The waste gas waste heat cascade recovery module realizes cascade waste heat recovery of waste gas through series connection of a gas-liquid heat exchanger and a flue gas source heat pump unit, and a heat preservation water tank is used as a buffer device; the waste heat utilization coupling natural gas heating and drying module adopts a coupling heating and drying mode that a heat pump unit is coupled with a natural gas burner, the two modules are combined to solve the problems of waste heat dispersity, intermittency and instability encountered by a front-end waste heat recovery end, and the energy efficiency is improved under the condition that the recovery efficiency and the energy efficiency ratio are not reduced. The temperature range of low-grade waste heat recycling is expanded, meanwhile, the single heating and drying mode of the rear-end utilization end is changed, waste waste heat is used for replacing part of natural gas in the heating and drying process, and comprehensive energy consumption and carbon emission of drying are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial waste gas waste heat recovery, and more specifically, relates to a heating and drying system. Background Art

[0002] Heat pump drying technology is an efficient and energy-saving drying solution. Its core lies in using heat pumps to absorb heat from the surrounding environment and transfer it to the heated object to achieve material drying. The working principle is that the heat pump drying system uses the reverse Carnot principle to achieve heat transfer and conversion through the circulation of refrigerant between components such as the evaporator, compressor, condenser and expansion valve. Compared with traditional drying technology, heat pump drying technology has the advantages of high efficiency and energy saving, environmental protection and safety, wide application range, good drying effect, etc. It can make full use of the heat in the external environment and reduce energy consumption without generating harmful gases and noise pollution. The combination of heat pump drying technology and industrial waste heat and waste energy recovery technology can quickly improve the energy efficiency ratio of the heat pump drying system, which will bring new opportunities for the development of heat pump drying technology and systems.

[0003] Existing heat pump drying system technologies mostly use devices such as heat exchangers and condensers to improve the drying system structure of the heat pump itself, or change the air duct structure to increase the working mode of the heat pump drying system, etc., mainly using a single heat pump system to achieve heating and drying in the drying room. The heat pump mode is often single, and most of them use air source heat pumps, with low air outlet temperature and low energy efficiency. In the field of high-temperature drying, the drying temperature is required to reach above 80°C, especially for the coating drying of products such as automobiles and engineering machinery. The drying temperature of the existing technology is difficult to meet the requirements, and the drying temperature rise is slow, and the drying efficiency is low. Summary of the invention

[0004] The purpose of the present invention is to address the above shortcomings and provide a heating and drying system, which adopts a step-by-step recovery of high-temperature exhaust gas waste heat as the waste heat source of a water source heat pump, and adopts a heat pump unit coupled with a natural gas burner to couple the heating and drying method. The natural gas burner is mainly used in the heating stage, and the waste heat recovery water source heat pump heating and drying method is mainly used in the insulation stage. The wasted waste heat is used to replace part of the natural gas used in the heating and drying process, thereby achieving energy saving and emission reduction effects.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The present invention provides a heating and drying system, including an exhaust gas waste heat cascade recovery module and a waste heat utilization coupled natural gas heating and drying module;

[0007] The exhaust gas waste heat cascade recovery module includes a gas-liquid heat exchanger and a flue gas source heat pump unit connected in series to the exhaust gas outlet duct, and the gas-liquid heat exchanger and the flue gas source heat pump unit are both connected to an insulation water tank;

[0008] The waste heat utilization coupled natural gas heating and drying module includes a water source heat pump unit, a natural gas burner and a drying room. The natural gas burner is connected to the drying room through the burner hot air duct, and the cold air outlet of the drying room is connected to the natural gas burner; the water source heat pump unit is connected to the natural gas burner through the waste heat utilization hot air front duct, and is connected to the burner hot air duct through the waste heat utilization hot air rear duct; the water source heat pump unit is connected to the insulation water tank.

[0009] Furthermore, the exhaust gas outlet duct includes an exhaust gas outlet duct and an exhaust gas outlet duct and an exhaust gas return duct connected to the exhaust gas outlet duct, the outlet of the exhaust gas outlet duct is connected to the gas-liquid heat exchanger and the flue gas source heat pump unit in sequence, and the outlet of the flue gas source heat pump unit is connected to the exhaust gas return duct; the exhaust gas outlet duct and the exhaust gas return duct are both provided with switching air valves, and the exhaust gas outlet duct between the exhaust gas outlet duct and the exhaust gas return duct is provided with an electric proportional valve.

[0010] Furthermore, the exhaust gas outlet duct and the exhaust gas return duct are both provided with a temperature sensor, a flow sensor and a pressure sensor; the exhaust gas return duct is also provided with an exhaust gas outlet and return flow induced draft fan.

[0011] Furthermore, the flue gas source heat pump unit includes a flue gas source heat pump unit evaporator, a flue gas source heat pump unit condenser, a flue gas source heat pump unit compressor and a flue gas source heat pump unit expansion valve which are connected in sequence, the air inlet end of the flue gas source heat pump unit compressor is connected to the exhaust gas outlet duct, and the air outlet end is connected to the exhaust gas return duct, and the liquid inlet and outlet of the flue gas source heat pump unit compressor and the gas-liquid heat exchanger are both connected to the insulation water tank.

[0012] Furthermore, the insulated water tank is provided with a liquid level sensor and a liquid temperature sensor.

[0013] Furthermore, the water source heat pump unit includes a water source heat pump unit evaporator, a water source heat pump unit condenser, a water source heat pump unit compressor and a water source heat pump unit expansion valve which are connected in sequence; the gas inlet of the water source heat pump unit compressor is connected to the waste heat utilization hot air front air duct, and the gas outlet is connected to the waste heat utilization hot air rear air duct; the liquid inlet and outlet of the water source heat pump unit evaporator are both connected to the insulation water tank.

[0014] Furthermore, the waste heat utilization hot air front air duct, the waste heat utilization hot air rear air duct and the burner hot air duct are all provided with switch air valves.

[0015] Furthermore, a waste heat utilization hot air induced draft fan is provided on the heat utilization hot air rear air duct.

[0016] Furthermore, a temperature sensor, a flow sensor and a pressure sensor are provided on the front air duct of the waste heat utilization hot air; and a temperature sensor is provided in the drying room.

[0017] Furthermore, a hot air inlet is provided above the drying room, and a cold air outlet is provided below the drying room; the hot air inlet of the drying room is connected to the hot air duct of the burner, and the cold air outlet of the drying room is connected to the natural gas burner through the drying room induced draft fan.

[0018] Furthermore, the hot air inlet and the cold air outlet of the drying room are both provided with filter screens.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention solves the problems of waste heat dispersion, intermittency and instability encountered at the front-end waste heat recovery end by combining the waste heat cascade recovery module with the waste heat utilization coupled with natural gas heating and drying module. While ensuring that the recovery efficiency and energy efficiency ratio are not reduced, the temperature range of low-grade waste heat recovery and utilization is expanded, and at the same time, the single heating and drying mode at the back-end utilization end is changed, which greatly reduces the comprehensive energy consumption of drying, and provides a complete solution for the problem of dispersed low-grade waste heat recovery and utilization.

[0021] The waste heat cascade recovery module of the present invention realizes the cascade waste heat recovery of the waste heat from the coating RTO outlet through the series connection of the gas-liquid heat exchanger and the flue gas source heat pump unit. By adding an insulation water tank in the middle as a buffer device, the problem of inability to continuously and stably supply heat caused by the dispersion, intermittency and fluctuation of the waste gas flow is improved.

[0022] The waste heat utilization coupled natural gas heating and drying module of the present invention couples the water source heat pump unit with the natural gas burner. The natural gas burner is mainly used in the heating stage and plays a supplementary role in the insulation stage. The waste heat recovery water source heat pump heating and drying method is mainly used in the insulation stage, realizing a comprehensive heating and drying method in the coating drying room that utilizes the natural gas burner to quickly heat up and recover waste heat for insulation. The wasted waste heat is used to replace part of the natural gas in the heating and drying process, which greatly reduces the drying energy consumption and carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a heating and drying system provided in Example 1 of the present invention;

[0024] Figure 2 A schematic diagram of the principle of a heating and drying system provided in Example 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the waste heat utilization heating and drying working mode of the waste heat utilization coupled with natural gas heating and drying module in the insulation stage described in Example 1;

[0026] Figure 4This is a schematic diagram of the natural gas heating and drying working mode of the waste heat utilization coupled natural gas heating and drying module in the temperature rising stage described in Example 1;

[0027] Figure 5 This is a control logic diagram of the waste heat cascade recovery module in the heating and drying system described in Example 2;

[0028] Figure 6 This is a control logic diagram of the waste heat utilization coupled with natural gas heating and drying module in the heating and drying system described in Example 2.

[0029] In the figure: 1. Exhaust gas outlet duct; 2. Gas temperature sensor for exhaust gas outlet duct; 3. Gas flow sensor for exhaust gas outlet duct; 4. Gas pressure sensor for exhaust gas outlet duct; 5. Electric switch air valve for exhaust gas outlet duct; 6. Electric proportional air valve for exhaust gas outlet duct; 7. Electric switch air valve for exhaust gas return duct; 8. Exhaust gas outlet and return draft fan; 9. Exhaust gas return duct; 10. Gas temperature sensor for exhaust gas return duct; 11. Gas flow rate for exhaust gas return duct Sensor; 12. Gas pressure sensor for exhaust gas return duct; 13. Flue gas source heat pump unit; 131. Evaporator for flue gas source heat pump unit; 132. Compressor for flue gas source heat pump unit; 133. Condenser for flue gas source heat pump unit; 134. Expansion valve for flue gas source heat pump unit; 14. Gas-liquid heat exchanger; 15. Exhaust gas outlet duct; 16. Liquid level sensor for insulated water tank; 17. Liquid temperature sensor for insulated water tank; 18. Insulated water tank; 19. Water source heat pump Group; 191, water source heat pump unit evaporator; 192, water source heat pump unit compressor; 193, water source heat pump unit condenser; 194, water source heat pump unit expansion valve; 20, waste heat utilization hot air duct gas temperature sensor; 21, waste heat utilization hot air duct gas flow sensor; 22, waste heat utilization hot air duct gas pressure sensor; 23, waste heat utilization hot air duct front electric switch air valve; 24, burner hot air duct electric switch air valve; 25, natural gas Burner; 26. Drying room induced draft fan; 27. Drying room outlet filter; 28. Waste heat utilization hot air rear air duct; 29. ​​Waste heat utilization hot air induced draft fan; 30. Waste heat utilization hot air duct rear electric switch air valve; 31. Burner hot air duct; 32. Drying room; 321. Drying room hot air inlet temperature sensor; 322. Drying room hot air inlet; 323. Drying room inlet filter; 324. Drying room cold air outlet; 33. Waste heat utilization hot air front air duct. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention will be described in more detail below in conjunction with the accompanying drawings and specific examples.

[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0033] Example 1

[0034] This embodiment provides a heating and drying system, such as Figure 1 As shown, it includes a waste gas waste heat cascade recovery module and a waste heat utilization coupled natural gas heating and drying module; the waste heat cascade recovery module is used for front-end waste heat recovery, and its core includes a gas-liquid heat exchanger 14, a flue gas source heat pump unit 13 and an insulation water tank 18, and the waste heat utilization coupled natural gas heating and drying module includes a water source heat pump unit 19, a natural gas burner 25 and a drying room 32; its principle is as follows Figure 2 As shown, the waste heat of high-temperature exhaust gas is recovered through the series cascade of the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13, which is used to heat the hot water in the insulation water tank 18 and maintain it at a certain temperature as the waste heat source of the water source heat pump unit 19; a heating and drying method in which the water source heat pump unit 19 and the natural gas burner 25 are coupled is adopted, and heating and drying are performed by the natural gas burner 25, which is mainly used in the heating stage and supplemented in the insulation stage; waste heat is recovered by the water source heat pump unit 19, and heating and drying are performed by waste heat, which is mainly used in the insulation stage; the wasted waste heat is used to replace part of the natural gas used in the heating and drying process, so as to achieve energy saving and emission reduction effects.

[0035] Specifically, Figure 1As shown, in this embodiment, the exhaust gas waste heat cascade recovery module of the heating and drying system includes an exhaust gas outlet duct 1 connected to the coating RTO, and the exhaust gas outlet duct 1 is connected to the exhaust gas outlet duct 15 and the exhaust gas return duct 9; the outlet of the exhaust gas outlet duct 15 is connected to the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13 in sequence, and the outlet of the flue gas source heat pump unit 13 is connected to the exhaust gas return duct 9; the exhaust gas outlet duct 15 is provided with an exhaust gas outlet duct electric switch air valve 5, and the exhaust gas return duct 9 is provided with an exhaust gas return duct electric switch air valve 7 and an exhaust gas outlet and return induced draft fan 8, and the exhaust gas outlet duct 1 between the exhaust gas outlet duct 15 and the exhaust gas return duct 9 is provided with an exhaust gas outlet duct electric proportional valve 6 to realize waste heat recovery of exhaust gases with different flow rates. In the working mode of fully recovering the waste heat of the exhaust gas at the coating RTO outlet, the electric switch air valve 5 of the exhaust gas outlet air duct and the electric switch air valve 7 of the exhaust gas return air duct are both opened, the electric proportional air valve 6 of the exhaust gas outlet air duct is all closed, and the exhaust gas at the coating RTO outlet all enters the exhaust gas outlet air duct 15; in the working mode of not recovering the waste heat of the exhaust gas at the coating RTO outlet, the electric switch air valve 5 of the exhaust gas outlet air duct and the electric switch air valve 7 of the exhaust gas return air duct are both closed, the electric proportional air valve 6 of the exhaust gas outlet air duct is all opened, and the exhaust gas at the coating RTO outlet all enters the chimney along the original coating RTO exhaust gas outlet air duct 1; in the working mode of partially recovering the waste heat of the exhaust gas at the coating RTO outlet, the electric switch air valve 5 of the exhaust gas outlet air duct and the electric switch air valve 7 of the exhaust gas return air duct are both opened, the electric proportional air valve 6 of the exhaust gas outlet air duct is opened according to the demand ratio, and a part of the exhaust gas at the coating RTO outlet enters the exhaust gas outlet air duct 15, and a part enters the chimney along the original coating RTO exhaust gas outlet air duct 1.

[0036] like Figure 1 As shown, in this embodiment, two groups of gas temperature, flow and pressure sensors are provided on the exhaust gas outlet duct 15 and the exhaust gas return duct 9. The exhaust gas outlet duct 15 is provided with an exhaust gas outlet duct gas temperature sensor 2, an exhaust gas outlet duct gas flow sensor 3 and an exhaust gas outlet duct gas pressure sensor 4 in sequence, and the exhaust gas return duct 9 is provided with an exhaust gas return duct gas temperature sensor 10, an exhaust gas return duct gas flow sensor 11 and an exhaust gas return duct gas pressure sensor 12 in sequence. The two groups of sensors monitor the conditions of the exhaust gas outlet duct 15 and the exhaust gas return duct 9 in real time, and adjust the working states of the gas-liquid heat exchanger 14 and the water source heat pump unit 13 in time by comparing the exhaust gas temperature, flow and pressure before and after the exhaust gas waste heat absorption.

[0037] In this embodiment, the liquid inlet and outlet of the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13 are connected to the insulated water tank 18; the gas-liquid heat exchanger 14 adopts a stainless steel fin tube structure to ensure the corrosion resistance of the heat exchanger. The gas-liquid heat exchanger 14 recycles the high-temperature coating exhaust gas of 70-80°C to 50-55°C, recycles the heat to heat the circulating water, and temporarily stores it in the insulated water tank 18 as the waste heat source of the water source heat pump unit 19.

[0038] like Figure 1 As shown, in this embodiment, the flue gas source heat pump unit 13 is composed of core components such as a flue gas source heat pump unit evaporator 131, a flue gas source heat pump unit condenser 132, a flue gas source heat pump unit compressor 133, and a flue gas source heat pump unit expansion valve 134. The air inlet end of the flue gas source heat pump unit evaporator 131 is connected to the exhaust gas outlet duct 15, and the air outlet end is connected to the exhaust gas return duct 9. The liquid inlet and outlet of the flue gas source heat pump unit compressor 133 are interconnected with the insulation water tank 18, which can recycle the medium-temperature painting exhaust gas of 50~55℃ to a low temperature of 15~20℃, and further recover the heat of the low-temperature exhaust gas. Different from the direct recycling of the gas-liquid heat exchanger 14, the obtained circulating water temperature of 45~50℃ is often lower than the return exhaust gas temperature of 50-55℃. The flue gas source heat pump unit 13 belongs to upgraded recycling, and the obtained circulating water temperature of 45~55℃ is often higher than the return exhaust gas temperature of 15~20℃, and has a high energy efficiency ratio, ensuring that the water temperature in the insulation water tank meets the working range requirements while saving energy.

[0039] like Figure 1 As shown, in this embodiment, the insulated water tank 18 is provided with a liquid temperature sensor 17 for the insulated water tank and a liquid level sensor 16 for the insulated water tank; the liquid temperature sensor 17 for the insulated water tank is linked with the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13 to ensure that the temperature of the insulated water tank 18 is within the required working range and is supplied to the subsequent water source heat pump unit 19; the liquid level sensor 16 for the insulated water tank is linked with the water pump to ensure that the water level in the insulated water tank 18 is within the required working range.

[0040] In this embodiment, the gas-liquid heat exchanger 14 belongs to the first stage of waste heat recovery of exhaust gas, and the flue gas source heat pump unit 13 belongs to the second stage of waste heat recovery of exhaust gas, which transfers the heat of low-temperature exhaust gas to the circulating water and temporarily stores it in the insulated water tank 18. Adding the insulated water tank 18 in the middle as a temporary heat storage buffer device can increase the stability of the system and is suitable for intermittent and unstable exhaust gas flow. The exhaust gas waste heat cascade recovery module composed of the core devices such as the gas-liquid heat exchanger 14, the flue gas source heat pump unit 14, and the insulated water tank 18 can recover the waste heat of exhaust gas to the greatest extent while ensuring that the recovery efficiency and energy efficiency ratio are not reduced, and is particularly applicable to complex working conditions with intermittent and unstable exhaust gas flow.

[0041] like Figure 1As shown, in this embodiment, the water source heat pump unit 19 is composed of core components such as a water source heat pump unit evaporator 191, a water source heat pump unit condenser 192, a water source heat pump unit compressor 193, and a water source heat pump unit expansion valve 194. The liquid inlet and outlet of the water source heat pump unit evaporator 191 are connected to the insulation water tank 18, and the 50°C medium-temperature water in the insulation water tank 18 is used as a waste heat source to supply the water source heat pump unit evaporator 191. Under the same evaporation temperature and condensation temperature conditions, the energy efficiency ratio of the water source heat pump is much better than that of the flue gas source heat pump, and when used for long-distance heat transportation, the heat loss of the water pipeline is much smaller than that of the air pipeline. The combined application of the insulation water tank 18 and the water source heat pump unit 19 not only improves the energy efficiency ratio of the system, but also reduces the heat loss during the system heat transportation process. The hot air outlet of the natural gas burner 25 is connected to the drying room 32 through the burner hot air duct 31, the gas inlet of the water source heat pump unit compressor 193 is connected to the natural gas burner 25 through the waste heat utilization hot air front duct 33, and the gas outlet is connected to the burner hot air duct 31 through the waste heat utilization hot air rear duct 28.

[0042] like Figure 1 As shown, in this embodiment, the waste heat utilization hot air rear air duct 28 is provided with a waste heat utilization hot air duct rear electric switching air valve 30 and a waste heat utilization hot air induced draft fan 29, the waste heat utilization hot air front air duct 33 is provided with a waste heat utilization hot air duct front electric switching air valve 23, and the burner hot air duct 31 is provided with a burner hot air duct electric switching air valve 24; the waste heat utilization hot air front air duct 33 is provided with a waste heat utilization hot air duct gas temperature sensor 20, a waste heat utilization hot air duct gas flow sensor 21 and a waste heat utilization hot air duct gas pressure sensor 22.

[0043] like Figure 1 As shown, in this embodiment, the air supply of the drying room 32 adopts the upper delivery and lower return mode, and the circulating hot air is sent in through the upper drying room hot air inlet 322, and discharged from the drying room cold air outlet 324 after passing through the working area, so as to ensure the high requirements of the drying room for temperature and humidity. The drying room hot air inlet 322 is provided with a drying room inlet filter 323, and the drying room cold air outlet 324 is connected to the drying room induced draft fan 26, and a three-layer drying room outlet filter 27 is provided in the middle. The use of the drying room inlet filter 323 ensures the cleanliness of the hot air entering the working area, and the use of the drying room outlet filter 27 ensures the cleanliness of the cold air entering the drying room induced draft fan 26 and the natural gas burner 25, and prevents the drying room induced draft fan 26 and the natural gas burner 25 from being blocked.

[0044] like Figure 3As shown, the waste heat utilization coupled natural gas heating and drying module adopts the waste heat utilization heating and drying working mode during the insulation stage, specifically: close the burner hot air duct electric switch air valve 24, open the waste heat utilization hot air duct front electric switch air valve 23 and the waste heat utilization hot air duct rear electric switch air valve 30, and open the waste heat utilization hot air induced draft fan 29 to overcome the wind resistance of the water source heat pump unit condenser 193 and the waste heat utilization hot air rear air duct 28, the waste heat utilization hot air induced draft fan 29 is used in conjunction with the waste heat utilization hot air duct gas pressure sensor 22 and the waste heat utilization hot air duct gas flow rate sensor 21 to ensure that the wind pressure of the waste heat utilization hot air rear air duct 28 is within the normal range; the waste heat utilization hot air duct gas temperature sensor 20 is linked with the water source heat pump unit 19 to ensure that the supply hot air temperature is maintained within the required range. The circulating air passes through the drying room induced draft fan 26 and the natural gas burner 25 (the natural gas burner is not working at this stage), and then enters the waste heat utilization hot air front air duct 33. After being heated by the water source heat pump unit condenser 193, it reaches the required working temperature and enters the drying room 32 from the waste heat utilization hot air rear air duct 28 and the burner hot air duct 31.

[0045] like Figure 4 As shown, the waste heat utilization coupled natural gas heating and drying module adopts the natural gas heating and drying working mode in the heating stage, specifically: close the front electric switch air valve 23 and the rear electric switch air valve 30 of the waste heat utilization hot air duct, open the electric switch air valve 24 of the burner hot air duct, and the circulating air passes through the drying room induced draft fan 26 and is heated by the natural gas burner 25 to reach the required working temperature, and directly enters the drying room 32 from the burner hot air duct 31. The temperature sensor 321 at the hot air inlet of the drying room is linked with the natural gas burner 25 to ensure that the temperature of the drying room 32 is maintained within the required range. The natural gas burner 25 works intermittently. After the temperature of the drying room 32 reaches the required range, the natural gas burner 25 stops working. In the heating, drying and heat preservation stage, when the waste heat utilization hot air supply is insufficient, the temperature sensor 321 at the hot air inlet of the drying room will show that the temperature does not meet the requirement. At this time, the natural gas burner 25 is turned on as a supplement in the heat preservation stage.

[0046] Example 2

[0047] This embodiment provides a specific workflow of the heating and drying system described in Embodiment 1. The heating and drying system described in Embodiment 1 is connected to the coating RTO, and its control logic is as follows: Figure 5 and Figure 6 As shown, the waste heat utilization system can only be turned on when the RTO waste gas treatment system operates normally, and is mainly used in the heating, drying and insulation stages of the drying room 32.

[0048] like Figure 5 and Figure 6 As shown, the whole system control process is as follows:

[0049] Open the electric switch air valve 5 of the exhaust gas outlet air duct, the electric switch air valve 7 of the exhaust gas return air duct, and the exhaust gas outlet and return draft fan 8, close the electric proportional air valve 6 of the exhaust gas outlet air duct, use the exhaust gas outlet air duct gas temperature sensor 2 and the exhaust gas outlet air duct gas flow sensor 3 to measure the exhaust gas temperature and flow rate to determine whether the working range requirements are met; if the requirements are not met, close the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13, adjust the opening of the electric proportional air valve 6 of the exhaust gas outlet air duct and the frequency of the exhaust gas outlet and return draft fan 8, if the requirements are met, open the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13;

[0050] The exhaust gas outlet duct gas pressure sensor 4 and the exhaust gas return duct gas pressure sensor 12 are used to measure and compare the pressures before and after exhaust gas recovery to determine whether the pressure difference is within a normal range, otherwise the anti-blocking program is started.

[0051] The gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13 continue to work, and the circulating water pump of the gas-liquid heat exchanger 14 loop is started;

[0052] The suction pressure of the flue gas source heat pump unit compressor 132 is detected to determine whether it is lower than the lower limit. If it is lower than the lower limit, the power supply of the compressor is cut off, otherwise the flue gas source heat pump unit 13 continues to work. The exhaust pressure of the flue gas source heat pump unit compressor 132 is continuously detected to determine whether it is higher than the upper limit. If it is higher than the upper limit, the power supply of the compressor is cut off, otherwise the flue gas source heat pump unit 13 continues to work;

[0053] The outlet water temperature of the flue gas source heat pump unit 13 is measured to determine whether it reaches the rated temperature range. If not, the number of compressors of the flue gas source heat pump unit 13 is increased. If reached, the loop circulating water pump of the flue gas source heat pump unit 13 is started.

[0054] Afterwards, the water level of the insulated water tank 18 is measured by the insulated water tank liquid level sensor 16 to determine whether the water level is in a safe range. If so, the water pump is turned off, otherwise, the water pump is turned on, and the temperature of the insulated water tank 18 is continued to be measured by the insulated water tank liquid temperature sensor 17 to determine whether the water temperature is in the required working range. If not, the circulation loop flow of the air-liquid heat exchanger 14 and the flue gas source heat pump unit 13 is increased. If it is reached, the insulated water tank 18 valve is opened, and the loop circulation water pump of the water source heat pump unit 19 and the water source heat pump unit 19 are turned on at the same time.

[0055] Like the flue gas source heat pump unit compressor 132, the suction pressure and exhaust pressure of the water source heat pump unit compressor 192 also need to be detected. If it is higher than the lower limit of the suction pressure and lower than the upper limit of the exhaust pressure, the water source heat pump unit 19 continues to work, and the outlet air temperature of the water source heat pump unit 19 is measured to determine whether it reaches the rated temperature. If it reaches it, the high-temperature air is passed into the drying room for heating and drying, otherwise the number of compressor working units continues to be increased.

[0056] Finally, the power of the water source heat pump unit 19 is tested to determine whether the power reaches the maximum value and the temperature of the drying room 32 is less than the required working range. If both conditions are met, the natural gas burner 25 is turned on as a supplement to the insulation stage, otherwise the water source heat pump unit 19 continues to be used for heating and drying.

[0057] In the present invention, the heat Q entering the thermal insulation water tank 18 is 水箱 The recovered heat Q from the gas-liquid heat exchanger 14 回收 The output heat Q of the flue gas source heat pump unit 13 烟气源输出 The heat Q entering the insulation water tank 18 per hour is jointly determined. 水箱 for:

[0058] .

[0059] The calculation method of the heat recovered by the gas-liquid heat exchanger 14 and the heat output by the flue gas source heat pump unit 13 is as follows:

[0060] ;

[0061] Among them, Q 回收 The gas-liquid heat exchanger 14 can recover the waste heat of the exhaust gas every hour; is the heat exchange efficiency of the gas-liquid heat exchanger 14; is the recovery efficiency of waste heat from exhaust gas, which is related to the structure and arrangement of the gas-liquid heat exchanger 14 for waste heat recovery from exhaust gas; C 废气1 is the constant-pressure specific heat capacity of exhaust gas, which is related to the exhaust gas temperature. Here, the value corresponding to the average of the high-temperature input exhaust gas temperature and the return exhaust gas temperature is taken; is the exhaust gas density, similar to the constant pressure specific heat capacity C 废气1 , here we also take the value corresponding to the average of the input exhaust gas temperature and the return exhaust gas temperature; V 废气1 is the standard flow rate of exhaust gas; T 输入废气1 is the input exhaust gas temperature, which is 70~80℃; T 回流废气1 The temperature of the reflux exhaust gas is 50~55℃. ;

[0062] Among them, Q 烟气源输出 The heat output per hour by the flue gas source heat pump unit 13; is the efficiency of the flue gas source heat pump unit 13; is the recovery efficiency of waste heat from exhaust gas, which is related to the structure and arrangement of the evaporator 131 of the flue gas source heat pump unit for waste heat recovery from exhaust gas; C 废气2 , 、V 废气2 are the constant pressure specific heat capacity of exhaust gas, exhaust gas density, and standard flow rate of exhaust gas, respectively, and the value corresponding to the average value of high-temperature input exhaust gas temperature and return exhaust gas temperature is taken; T 输入废气2 is the input exhaust gas temperature, which is 50~55℃; T 回流废气1 is the temperature of the reflux exhaust gas, which is 15~20℃; r i W is the efficiency of converting the work energy of the i-th compressor of the flue gas source heat pump unit 13 into heat energy; i is the work done by the i-th compressor of the flue gas source heat pump unit 13 in one hour. In this embodiment, the flue gas source heat pump unit 13 has 4 compressors (ie, the maximum value of i is 4), and can perform 4-level energy regulation, which can ensure that the four compressors do not have to be in working state all the time.

[0063] In the present invention, the heat output by the water source heat pump unit 19 is Q 水源输出 The heat Q stored mainly in the thermal insulation water tank 18 水箱 It is decided that the insulated water tank 18 is used as an intermediate buffer device to temporarily store the heat recovered by the gas-liquid heat exchanger 14 and the flue gas source heat pump unit 13, and transmit it to the water source heat pump unit 19, as the waste heat source of the water source heat pump unit 19, to heat and dry the drying room.

[0064] The water source heat pump unit 19 outputs heat Q per hour 水源输出 The calculation formula is as follows:

[0065] ;

[0066] ;

[0067] in, is the efficiency of the water source heat pump unit 19; r j is the efficiency of converting the work energy of the jth compressor of the water source heat pump unit 19 into heat energy, W j Q is the work done by the jth compressor of the water source heat pump unit 19 in one hour; in this embodiment, the water source heat pump unit 19 has 6 compressors (i.e., the maximum value of j is 6), and 6 levels of energy regulation can be performed, which can ensure that the six compressors do not have to be in working state all the time; 管路热损 is the heat lost during the process of hot water being transported from the insulated water tank 18 to the drying room 32, T v is the high temperature hot water temperature, T A is the ambient temperature, D0 is the outer diameter of the hot water pipe insulation layer, D1 is the inner diameter of the insulation layer, , is the thickness of the insulation layer, is the thermal conductivity of the insulation material, is the heat dissipation coefficient of the outer surface of the insulation layer to the atmosphere, and l is the length of the hot water pipe.

[0068] The present invention adopts a gas-liquid heat exchanger 14 and a flue gas source heat pump unit 13 in series to perform cascade waste heat recovery, adds an insulated water tank 18 in the middle as a buffer device, and couples the water source heat pump unit 19 with the natural gas burner 25 for heating and drying. The method solves the problems of dispersed, intermittent and unstable waste heat encountered at the front-end waste heat recovery end. While ensuring that the recovery efficiency and energy efficiency ratio are not reduced, the temperature range of low-grade waste heat recovery and utilization is expanded, and at the same time, the single heating and drying mode of the back-end utilization end is changed, which greatly reduces the comprehensive energy consumption of drying, and provides a complete solution to the problem of dispersed low-grade waste heat recovery and utilization.

[0069] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Without departing from the scope and technical principles of the described embodiments, many modifications and changes are obvious to those of ordinary skill in the art, and these modifications and changes should also be regarded as the scope of protection of the present invention.

Claims

1. A heating and drying system, characterized in that: It includes a waste gas waste heat cascade recovery module and a waste heat utilization coupled with natural gas heating and drying module; The exhaust gas waste heat cascade recovery module comprises a gas-liquid heat exchanger (14) and a flue gas source heat pump unit (13) connected in series to the exhaust gas outlet duct, and the gas-liquid heat exchanger (14) and the flue gas source heat pump unit (13) are both connected to an insulation water tank (18); The waste heat utilization coupled natural gas heating and drying module comprises a water source heat pump unit (19), a natural gas burner (25) and a drying room (32); the natural gas burner (25) is connected to the drying room (32) via a burner hot air duct (31), and a cold air outlet of the drying room (32) is connected to the natural gas burner (25); the water source heat pump unit (19) is connected to the natural gas burner (25) via a waste heat utilization hot air front duct (33), and is connected to the burner hot air duct (31) via a waste heat utilization hot air rear duct (28); the water source heat pump unit (19) is also connected to a thermal insulation water tank (18).

2. The heating and drying system according to claim 1, characterized in that: The exhaust gas outlet duct comprises an exhaust gas outlet duct (1), an exhaust gas outlet duct (15) and an exhaust gas return duct (9) connected to the exhaust gas outlet duct (1); the outlet of the exhaust gas outlet duct (15) is connected to the gas-liquid heat exchanger (14) and the flue gas source heat pump unit (13) in sequence; the outlet of the flue gas source heat pump unit (13) is connected to the exhaust gas return duct; both the exhaust gas outlet duct (15) and the exhaust gas return duct (9) are provided with switch air valves; and the exhaust gas outlet duct (1) between the exhaust gas outlet duct (15) and the exhaust gas return duct (9) is provided with an electric proportional valve.

3. The heating and drying system according to claim 2, characterized in that: The exhaust gas outlet duct (15) and the exhaust gas return duct (9) are both provided with a temperature sensor, a flow sensor and a pressure sensor.

4. The heating and drying system according to claim 2, characterized in that: The flue gas source heat pump unit (13) comprises a flue gas source heat pump unit evaporator (131), a flue gas source heat pump unit condenser (132), a flue gas source heat pump unit compressor (133) and a flue gas source heat pump unit expansion valve (134) which are connected in sequence; the air inlet end of the flue gas source heat pump unit evaporator (131) is connected to the exhaust gas outlet duct (15), and the air outlet end is connected to the exhaust gas return duct (9); the liquid inlet and outlet of the flue gas source heat pump unit compressor (133) and the gas-liquid heat exchanger (14) are both connected to the thermal insulation water tank (18).

5. The heating and drying system according to claim 2, characterized in that: The thermal insulation water tank is provided with a liquid level sensor (16) and a liquid temperature sensor (17).

6. The heating and drying system according to claim 1, characterized in that: The water source heat pump unit (19) comprises a water source heat pump unit evaporator (191), a water source heat pump unit condenser (192), a water source heat pump unit compressor (193) and a water source heat pump unit expansion valve (194) which are connected in sequence; the gas inlet of the water source heat pump unit compressor (193) is connected to the waste heat utilization hot air front air duct (33), and the gas outlet is connected to the waste heat utilization hot air rear air duct (28); the liquid inlet and outlet of the water source heat pump unit evaporator (191) are both connected to the thermal insulation water tank (18).

7. The heating and drying system according to claim 6, characterized in that: The waste heat utilization hot air front air duct (33), the waste heat utilization hot air rear air duct (28) and the burner hot air duct (31) are all provided with on / off air valves.

8. The heating and drying system according to claim 6, characterized in that: The waste heat utilization hot air rear air duct (28) is also provided with a waste heat utilization hot air induced draft fan (29).

9. The heating and drying system according to claim 6, characterized in that: A temperature sensor, a flow sensor and a pressure sensor are provided on the waste heat utilization hot air front air duct (33); and a temperature sensor is provided in the drying room (32).

10. The heating and drying system according to claim 6, characterized in that: The drying room (32) is provided with a hot air inlet at the top and a cold air outlet at the bottom; the hot air inlet of the drying room (32) is connected to the hot air duct (31) of the burner, and the cold air outlet of the drying room (32) is connected to the natural gas burner (25) via the drying room induced draft fan (26).

Images