A drying system and method

Abstract

The present invention discloses a drying system and method, which relates to the field of drying and aims to solve the limitations of low-temperature heat pump dehumidification drying and the still relatively high energy consumption. The drying system includes: a feeding assembly, a drying device, a discharging assembly, a steam conversion device, and a steam compression device. The feeding assembly is communicated with the feeding port of the drying device, the discharging assembly is communicated with the discharging port of the drying device, the steam outlet of the drying device is communicated with the steam inlet of the steam conversion device, the steam outlet of the steam conversion device is communicated with the steam inlet of the drying device through the steam compression device, and the condensate outlet of the drying device is communicated with the condensate inlet of the steam conversion device. The drying system and method provided by the present invention are used to reduce drying energy consumption and save production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of drying, and particularly to a drying system and method. Background Art

[0002] Sludge drying is an important link in sludge treatment, and there are mainly drying methods such as natural drying, solar drying, and thermal drying. Natural drying and solar drying have large floor areas and are not suitable for large-scale promotion. Thermal drying has a high rate, but also high energy consumption, which restricts its large-scale promotion. Low-temperature heat pump dehumidification drying is essentially a direct-contact belt drying, which uses heat pump technology, makes full use of the exhaust waste heat of the drying equipment, basically does not require steam, and has high energy efficiency, and has developed well in recent years.

[0003] However, for low-temperature heat pump dehumidification drying, both the evaporator and the condenser are for heat medium to exchange heat with dirty air, with a low heat transfer coefficient, a high heat transfer temperature difference required, a high heat medium temperature rise, a large compression ratio, and a high heat pump power consumption. In addition, this system does not recover the waste heat of the discharged material, and also needs to rely on external circulating cooling water to assist in cooling and condensing the heat medium steam to maintain the heat medium circulation, losing some heat, resulting in still high power consumption. Summary of the Invention

[0004] The purpose of the present invention is to provide a drying system and method, which reduce the drying energy consumption and save the production cost.

[0005] To achieve the above purpose, in the first aspect, the present invention provides the following technical solution:

[0006] A drying system includes: a feeding component, a drying device, a discharging component, a steam conversion device, and a steam compression device. The steam conversion device includes a heat exchange or washing device. The feeding component is communicated with the feeding port of the drying device, and the discharging component is communicated with the discharging port of the drying device;

[0007] The steam outlet of the drying device is communicated with the steam inlet of the steam conversion device. The steam outlet of the steam conversion device is communicated with the steam inlet of the drying device through the steam compression device. The condensate outlet of the drying device is communicated with the condensate inlet of the steam conversion device;

[0008] The feeding component and the discharging component are respectively sealed with the drying device, and the steam pressure in the drying chamber of the drying device is the same as the external atmospheric pressure;

[0009] Compared with the prior art, in the drying system provided by the present invention, the feeding assembly is connected to the feeding port of the drying device in a sealed manner, and the discharging assembly is connected to the discharging port of the drying device in a sealed manner. Therefore, the wet material can be conveyed to the drying device by the feeding assembly and sealed feeding can be achieved. After drying is completed, the dried material is discharged through the discharging assembly and sealed discharging can be achieved. Since the steam outlet of the steam conversion device is connected to the steam inlet of the drying device through the steam compression device, before drying, the steam conversion device can convey clean steam to the drying device through the steam compression device, and the wet material is dried by the clean steam. At this time, the moisture in the wet material is discharged to the steam conversion device in the form of steam. After the steam dries the wet material, at least part of it is discharged in the form of condensed water. Since the condensed water outlet of the drying device is connected to the condensed water inlet of the steam conversion device, the condensed water can be discharged into the steam conversion device, converted into clean steam in the steam conversion device, and then compressed and heated by the steam compression device. The compressed and heated steam is introduced into the drying device to continue drying the wet material, forming a cycle. That is to say, the drying system of the embodiment of the present invention only needs to physically heat the water in the steam conversion device for a short time after starting the machine to form a small amount of water vapor, and then compress and heat it by the steam compression device 500 and introduce it into the drying device to dry the wet material, so as to realize the recycling of the steam in the wet material. Therefore, it is not necessary to continuously heat the steam conversion device, reducing the power consumption and saving the production cost.

[0010] In addition, the feeding assembly and the discharging assembly provided by the present invention are respectively sealed with the drying device, and the air pressure in the drying chamber of the drying device is the same as the external atmospheric pressure. By physically sealing the drying device with the feeding assembly and the discharging assembly and keeping the steam pressure in the drying chamber of the drying device the same as the external atmospheric pressure, the steam pressure in the drying chamber can be balanced with the pressure of the external environment, so that air will not enter the drying chamber of the drying device and the second steam, and the second steam will not leak out, realizing the normal operation of the steam conversion device.

[0011] As can be seen from the above, the drying system of the embodiment of the present invention reduces the consumption of steam and power consumption, and saves the production cost.

[0012] In a second aspect, an embodiment of the present invention further provides a drying method, including:

[0013] Conveying wet material to a drying device by using a feeding assembly, and the drying device drying the wet material by using first steam to obtain dried material;

[0014] Among them, during the process of drying the wet material by the drying device using the first steam, the moisture in the wet material is discharged to the steam conversion device in the form of the second steam. After drying the wet material, at least part of the first steam is discharged to the steam conversion device in the form of condensed water. When the steam conversion device is a heat exchange device, the condensed water absorbs the heat of the second steam in the steam conversion device and is converted into the third steam. When the steam conversion device is a washing device, the condensed water flashes and vaporizes in the steam conversion device and is jointly converted into the third steam with the second steam. The steam compression device is used to compress and heat up the third steam, and the compressed and heated third steam is introduced into the drying device.

[0015] Compared with the prior art, the beneficial effects of the drying method provided by the embodiment of the present invention are the same as those of the drying system in the first aspect, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute a limitation to the present invention.

[0017] Figure 1 The process flow diagram of the first drying system provided by the embodiment of the present invention is shown;

[0018] Figure 2 The process flow diagram of the second drying system provided by the embodiment of the present invention is shown;

[0019] Figure 3 The sludge drying energy balance diagram of the drying system provided by the embodiment of the present invention for daily treatment of 100 tons of wet sludge is shown;

[0020] Figure 4 The waste heat recovery system energy balance diagram of the drying system provided by the embodiment of the present invention for daily treatment of 100 tons of wet sludge is shown.

[0021] REFERENCE SIGNS:

[0022] 100 - Feed assembly; 101 - Feed preheating unit; 102 - Feed unit; 200 - Drying device; 300 - Discharge assembly; 301 - Discharge unit; 302 - Discharge heat release unit; 400 - Steam conversion device; 500 - Steam compression device; 600 - Heating device; 700 - Refrigerant container; 800 - Refrigerant temperature adjustment assembly; 801 - First refrigerant temperature adjustment device; 802 - Second refrigerant temperature adjustment device; 900 - Controllable valve; 1000 - Automatic control valve; 1100 - Temperature sensor; 1200 - Temperature sensing assembly; 1300 - Multi-stage flash evaporation unit; 1400 - Gas-liquid separation device; 1500 - Waste liquid pipeline. Detailed implementation manners

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0025] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. "Several" means one or more unless otherwise specifically defined.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 thus cannot be understood as a limitation to the present invention.

[0027] 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 directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Drying devices are widely used in the fields of food, chemical industry, petrochemical industry, dyes, etc., as well as in many fields such as garbage drying and incineration, biomass fuel drying, sludge drying, etc. Drying equipment has high energy consumption and high operating costs. Sludge is a "world problem" in sewage treatment. Sludge drying is an important link in sludge treatment, mainly including natural drying, solar drying, thermal drying and other drying methods. Natural drying and solar drying have large floor areas and are not suitable for large-scale promotion. Thermal drying has a high rate, but also has high energy consumption, which restricts its large-scale promotion. Low-temperature heat pump dehumidification drying is essentially a direct-contact belt drying. It uses heat pump technology, makes full use of the exhaust waste heat of the drying equipment, basically does not need steam, and has high energy efficiency. It has developed well in recent years.

[0029] Low-temperature heat pump dehumidification drying is essentially a direct-contact belt drying. Since it uses heat pump technology, makes full use of the exhaust waste heat of the drying equipment, basically does not need steam, and has high energy efficiency. It has developed well in recent years. However, for low-temperature heat pump dehumidification drying, both the evaporator and the condenser are for the heat medium to exchange heat with the dirty air. The heat transfer coefficient is low, a relatively high heat transfer temperature difference is required, the heat medium temperature rises, the compression ratio is large, and the power consumption of the heat pump is high. In addition, this system does not recover the waste heat of the dried material, and external circulating cooling water is also needed to assist in cooling and condensing the heat medium steam to maintain the heat medium circulation, resulting in some heat loss and still relatively high power consumption.

[0030] In view of the above problems, the embodiments of the present invention provide a drying system to reduce the consumption of steam and power consumption, save production costs, and solve the problems in the prior art that low-temperature heat pump dehumidification drying has a low heat transfer coefficient, requires a relatively high heat transfer temperature difference, a high heat medium temperature, a large compression ratio, and a high power consumption of the heat pump. It should be understood that this drying system can not only dry sludge, but also dry food, chemical raw materials, petroleum products, dyes or biomass fuels, which is not limited here.

[0031] Figure 1 The process flow chart of the first drying system provided by the embodiments of the present invention is shown. As Figure 1As shown in the figure, a drying system according to an embodiment of the present invention includes: a feeding assembly 100, a drying device 200, a discharging assembly 300, a steam conversion device 400, and a steam compression device 500. The feeding assembly 100 is communicated with the feeding port of the drying device 200, the discharging assembly 300 is communicated with the discharging port of the drying device 200, the steam outlet of the drying device 200 is communicated with the steam inlet of the steam conversion device 400, the steam outlet of the steam conversion device 400 is communicated with the steam inlet of the drying device 200 through the steam compression device 500, and the condensate outlet of the drying device 200 is communicated with the condensate inlet of the steam conversion device 400. Among them, the steam conversion device 400 can pre-store water, and a heater can also be provided at the bottom of the steam conversion device 400 for heating the water in the steam conversion device 400. The drying device 200 can be an indirect heat conduction dryer, and the drying device has a sandwich for introducing steam.

[0032] As Figure 1 shown in the figure, the steam conversion device 400 of the first embodiment of the present invention is a water-vapor heat exchanger, for example: a falling film evaporator, which is used for heat exchange of the second steam, and the heat transfer temperature difference of the falling film evaporator is not higher than 5°C. The drying device can be an indirect drying device such as a vertical disc drying device, a paddle drying device, a horizontal disc drying device, a thin layer drying device, etc., preferably a vertical disc drying device.

[0033] During specific implementation, the heater can be used to heat the water in the steam conversion device 400 for a short time, so that at least a part of the water in the steam conversion device 400 is converted into steam. For the convenience of description, this part of the steam can be defined as the first steam. When the first steam passes through the steam compression device 500, the steam compression device 500 can compress and heat up the first steam, so that the temperature of the first steam rises to 120-180°C, preferably 135°C, and then the first steam is introduced into the sandwich of the drying device 200. At the same time, the feeding assembly 100 can transport the wet material to the drying device 200. Based on this, the wet material in the drying device 200 can be dried by using the first steam. During the drying process, the water in the wet material will be converted into steam. For the convenience of description, this part of the steam can be defined as the second steam. At this time, the second steam can be discharged to the steam conversion device 400, and the condensate discharged from the drying device is converted into clean steam and then compressed and heated up to 120-180°C, preferably 135°C by using the steam compression device 500, and then introduced into the drying device 200 to continue drying the wet material. It should be understood that the wet material is the raw material to be dried, and the wet material can be wet sludge, wet chemical raw materials, wet food, wet dyes, or other wet materials that need to be dried, which will not be elaborated here.

[0034] On this basis, different from the secondary steam recompression technology of MVR, the embodiment of the present invention adopts the heat pump principle. The steam compression device compresses the heat medium steam discharged from the steam conversion device 400. There is no non-condensable gas in the heat medium steam used as the drying heat source. Therefore, the heat transfer efficiency of the drying equipment is much higher than that of the MVR drying system. In the embodiment of the present invention, the steam conversion device is used as the evaporator, water is used as the heat medium, the steam compression device is used as the heat pump, and the drying device is used as the condenser to form a closed circulation system for heat recovery, reducing energy consumption.

[0035] Exemplarily, the above-mentioned steam compression device may be a steam compressor. The steam compressor may adopt single-stage, two-stage compression or two compressors in series. Depending on the evaporation capacity, the steam compressor may adopt a centrifugal steam compressor, a Roots steam compressor or a screw steam compressor, which is not limited herein. The saturation temperature rise of the steam compression device is above 20°C and below 90°C (preferably 40°C).

[0036] Exemplarily, the heat medium inlet of the above-mentioned steam conversion device 400 is also communicated with the steam inlet of the steam compression device 500. When the steam temperature in the steam compression device 500 is greater than the set value, for example, 140°C, the heat medium water of the steam conversion device 400 can be used as the steam desuperheating water of the steam compression device to desuperheat the steam in the steam compression device. It should be understood that the introduction position of the steam desuperheating water can be set at a suitable position in the system according to actual needs. For example: the addition position of the desuperheating water can be set by the compressor manufacturer.

[0037] In an optional manner, the above-mentioned feeding assembly 100 and discharging assembly 300 are respectively sealed with the drying device 200. When the feeding assembly 100 and the discharging assembly 300 are respectively sealed with the drying device 200, when the feeding assembly 100 conveys wet materials to the drying device 200, air can be prevented from entering the drying device. When the drying device 200 conveys dry materials to the discharging assembly 300, air can also be prevented from entering the drying device. Thus, the second steam generated when the drying device 200 dries the wet materials will not be mixed with air, reducing the amount of non-condensable gas brought into the steam conversion device 400 when the drying device 200 conveys the second steam. At the same time, the feeding assembly 100 and the discharging assembly 300 are respectively sealed with the drying device 200, and the steam generated during the drying process of the wet materials in the drying device can also be prevented from leaking through the discharging assembly or the feeding assembly. On the one hand, environmental pollution is reduced. On the other hand, the waste heat (second steam) in the drying device 200 can be more effectively recovered and utilized, enabling the waste heat of the drying system to be recycled and reducing production costs.

[0038] In addition, the vapor pressure in the drying chamber of the drying device provided by the present invention is the same as the external atmospheric pressure. For example, the vapor in the drying chamber of the drying device can be 1 atmosphere. By physically sealing the drying device using the feeding assembly and the discharging assembly, and at the same time keeping the vapor pressure in the drying chamber of the drying device the same as the external atmospheric pressure, the vapor pressure in the drying chamber can be balanced with the pressure of the external environment, so that air will not enter the drying chamber of the drying device and the second steam, and the second steam will not leak out, realizing the normal operation of the steam conversion device.

[0039] Exemplarily, the temperature of the second steam discharged from the above-mentioned drying device 200 to the steam conversion device 400 is 100 °C. A temperature control device can be provided at the outlet of the second steam. The temperature control device includes an automatic control valve 1000 and a temperature sensor 1100. When the temperature sensor monitors that the temperature at the outlet of the second steam is less than 100 °C, the control valve is controlled to close slightly. When the temperature sensor monitors that the temperature at the outlet of the second steam is greater than 100 °C, the control valve is controlled to open wider, so that the second steam is transported to the steam conversion device 400. Based on this, the steam pressure in the drying chamber of the drying device 200 can be basically kept consistent with the external atmospheric pressure. When the sealing system of the wet material entering and leaving the drying device 200 is not effective, the proportion of air mixed in the second steam can be reduced to the lowest again. Except that the second steam at the steam outlet of the drying device is set to about 100 °C to keep the vapor pressure in the drying device balanced with the environmental pressure, the high or low settings of other temperatures in the embodiments of the present invention are only related to energy efficiency, equipment selection, equipment investment, etc., and are not used to limit the present invention. The solutions obtained by adjusting the temperatures of each part on the basis of the present invention all fall within the scope of the claims of the present invention and its equivalent technologies.

[0040] As can be seen from the above, the drying system of the embodiment of the present invention only needs to physically heat the water in the steam conversion device 400 for a short time to form a small amount of water vapor after starting up, and then use the steam compression device 500 to compress and heat up and introduce it into the drying device to dry the wet material, so that the recovery and utilization of the second steam in the wet material can be realized. Therefore, it is not necessary to continuously heat the drying system, reducing the heating energy consumption and saving the production cost.

[0041] In an alternative manner, such as Figure 1As shown in the figure, a drying system according to an embodiment of the present invention further includes a refrigerant container 700 and a refrigerant temperature adjustment assembly 800. The drying device 200 further has a condensation unit. The drying device 200 can be used as a condenser to condense the steam in the interlayer and then discharge it. The condensate outlet of the drying device 200 is communicated with the steam inlet of the steam conversion device 400 through the refrigerant temperature adjustment assembly 800. The refrigerant temperature adjustment assembly 800 can adjust the temperature of the refrigerant discharged from the refrigerant container 700 by means of heat exchange. The temperature of the condensate at the condensate outlet of the drying device 200 is higher than the temperature of the refrigerant at the outlet of the heat absorption chamber of the feeding assembly 100. It should be understood that the refrigerant container 700 can be used to store a refrigerant medium, such as soft water or demineralized water, or other refrigerant media, which is not limited herein. The heat absorption chamber of the feeding assembly 100 can be an interlayer provided on the feeding assembly, and the interlayer is used to isolate the wet material from the refrigerant.

[0042] Exemplarily, as Figure 1 shown in the figure, the outlet of the above-mentioned refrigerant container 700 is communicated with the drying device 200, the inlet of the heat release chamber of the refrigerant container 700 is communicated with the discharging assembly, the outlet of the heat release chamber of the discharging assembly 300 is communicated with the refrigerant inlet of the refrigerant temperature adjustment assembly 800, and the refrigerant outlet of the refrigerant temperature adjustment assembly 800 is communicated with the inlet of the heat absorption chamber of the feeding assembly 100. It should be understood that the heat release chamber of the discharging assembly 300 can be an interlayer provided on the discharging assembly 300, and the interlayer is used to isolate the dry material from the refrigerant. At the same time, the drying device 200 is used as a condenser to condense the first steam to obtain condensate. The outlet of the condensate passes through the refrigerant temperature adjustment assembly 800, and the temperature of the refrigerant is increased by means of heat exchange. The condensate outlet of the refrigerant temperature adjustment assembly 800 is communicated with the condensate inlet of the steam conversion device 400. That is to say, the condensate of the drying device 200 can also be cooled by the refrigerant temperature adjustment assembly 800 and then enter the steam conversion device 400, so that the temperature of the condensate entering the steam conversion device 400 is lower than the temperature of the second steam, which is convenient for using the condensate to exchange heat with the second steam.

[0043] During specific implementation, the refrigerant container 700 delivers the refrigerant to the interlayer of the discharging component 300. At this time, the refrigerant can absorb the heat of the dry material in the discharging component 300, causing the refrigerant to heat up. The heated refrigerant then enters the refrigerant temperature adjustment component 800. The above-mentioned drying device 200 can act as a condenser to condense the first steam, obtain condensed water, and deliver the condensed water to the refrigerant temperature adjustment component 800. At this time, since the temperature of the condensed water at the condensed water outlet of the drying device 200 is higher than the temperature of the refrigerant at the heat absorption chamber outlet of the feeding component 100, the refrigerant temperature adjustment component 800 can be used to conduct heat exchange between the refrigerant and the condensed water, enabling the refrigerant to be further heated by the condensed water and the condensed water to be cooled by the refrigerant. In addition, the heated refrigerant is discharged from the refrigerant temperature adjustment component 800 and delivered to the feeding component 100 to preheat the wet material. During the preheating process, the wet material can absorb the heat of the refrigerant, and at the same time, the refrigerant can be cooled down and discharged into the refrigerant container for continued use.

[0044] Exemplarily, as Figure 1 shown, the above-mentioned refrigerant temperature adjustment component 800 may include a first refrigerant temperature adjustment device 801 and a second refrigerant temperature adjustment device 802. The refrigerant inlet of the first refrigerant temperature adjustment device 801 is communicated with the outlet of the heat release chamber of the discharging component, the refrigerant outlet of the first refrigerant temperature adjustment device is communicated with the refrigerant inlet of the second refrigerant temperature adjustment device, and the refrigerant outlet of the second refrigerant temperature adjustment device is communicated with the interlayer inlet of the feeding component. Among them, the first refrigerant temperature adjustment device 801 and the second refrigerant temperature adjustment device 802 may adopt plate heat exchangers or other heat exchangers, which are not limited herein.

[0045] During specific implementation, the refrigerant discharged from the heat release chamber of the discharging component 300 can enter the first refrigerant temperature adjustment device 801, be further heated in temperature and then discharged to the second refrigerant temperature adjustment device 802, and then the condensed water discharged from the drying device to the second refrigerant temperature adjustment device 802 is used to continue heating the temperature to obtain the heated refrigerant. At this time, the heated refrigerant is introduced into the interlayer of the feeding component to preheat the wet material. The first refrigerant temperature adjustment device 801 and the second refrigerant temperature adjustment device 802 are used to exchange heat with the refrigerant discharged from the heat release chamber of the discharging component 300 so that the refrigerant has a higher temperature to preheat the wet material, thereby reducing the steam consumption during the drying of the drying device 200, achieving the cascade utilization of energy, and saving the power consumption of the steam compression device.

[0046] It can be seen that in the embodiment of the present invention, not only can the waste heat of the dry material in the discharging assembly be recovered by using the refrigerant discharged from the closed-loop refrigerant container, but also the waste heat of the condensed water discharged from the drying device and the heat of the waste liquid discharged from the steam conversion device can be used to further heat the refrigerant discharged from the heat release chamber of the discharging assembly. The heated refrigerant is used to preheat the wet material in the feeding assembly. After the wet material absorbs heat, the refrigerant is cooled, and the cooled refrigerant can continue to perform the foregoing operations.

[0047] Exemplarily, as Figure 1 shown, the outlet of the refrigerant container 700 is sequentially communicated with the inlet of the refrigerant container 700 through the heat absorption chamber of the discharging assembly 300, the refrigerant temperature adjustment assembly 800, and the heat absorption chamber of the feeding assembly 100.

[0048] Based on this, the drying system of the embodiment of the present invention realizes a closed-loop system. Both the condensed water and the refrigerant can be recycled. The refrigerant water is used as a heat recovery medium to recover the waste heat of the dry material and the dirty condensed water to preheat the wet material. The second steam generated during the drying process of the wet material can also be continuously discharged to the steam conversion device for recycling. During the operation of the entire system, only a small amount of power consumption will be generated when the steam conversion device is turned on and when the steam compression device compresses and heats up. The rest of the energy comes from the system itself, greatly reducing the energy consumption and power consumption of the drying system and saving the production cost.

[0049] Exemplarily, as Figure 1 shown, the feeding assembly 100 of the embodiment of the present invention may further include a feeding preheating unit 101 and a sealed feeding unit 102, and the discharging assembly 300 may include a sealed discharging unit 301 and a discharging heat release unit 302. The discharging port of the feeding preheating unit 101 is communicated with the feeding port of the sealed feeding unit 102, the discharging port of the sealed feeding unit 102 is hermetically communicated with the feeding port of the drying device 200, the discharging port of the drying device 200 is hermetically communicated with the feeding port of the sealed discharging unit 301, and the discharging port of the sealed discharging unit 301 is communicated with the feeding port of the discharging heat release unit 302.

[0050] For example, as Figure 1As shown, the above-mentioned feeding assembly 100 and discharging assembly 300 can be sealed with the drying device 200 in any sealing manner. For example: the above-mentioned feeding preheating unit 101 and discharging heat-releasing unit 302 can be set as spiral feeding preheaters, and the sealed feeding unit 102 can be a sealed feeding unit with dehydration function, such as a plug screw feeder or other sealed feeding units with dehydration function, which are not limited here. The sealed discharging unit 301 can be a plug screw discharger. Other sealing devices can also be selected for sealing, which are not limited here. It should be understood that when the sealed feeding unit 102 is a plug screw feeder, the plug screw feeder has an extrusion dehydration effect on some materials, such as domestic waste, especially after preheating, dehydration is easier, so that the moisture entering the drying device will be further reduced, thereby further reducing the drying energy consumption. Both the feeding preheating unit 101 and the discharging heat-releasing unit 302 have interlayers. For the convenience of description, the interlayer of the feeding preheating unit 101 can be defined as an endothermic cavity, and the interlayer of the discharging heat-releasing unit 302 can be defined as an exothermic cavity.

[0051] The feeding preheating unit in the embodiment of the present invention takes the heating spiral as an example, but is not limited to the heating spiral, and can be any feeding preheating unit using hot water as a heat source, such as: a hot water type disk dryer, a spiral dryer, etc., which are not limited here. It should be understood that if the feeding preheating unit 101 can be sealed with the drying device 200, the feeding unit does not need to be provided. It should be understood that the discharging assembly adopts a cooling spiral (preferably a shafted cooling spiral), and the feeding assembly adopts a sludge heating spiral (preferably a shaftless heating spiral), which can take into account both transportation and heat exchange.

[0052] During specific implementation, the wet material to be dried is transported to the feeding preheating unit 101 for preheating. After the preheating is completed, it is transported to the feeding unit 102, and then transported to the drying device 200 by the feeding unit 102 to dry the wet material. After drying is completed, the dried material can be transported through the drying device 200 to the discharging unit, and then transported to the discharging heat-releasing unit 302 for heat release, so as to output the dried material. By setting the feeding preheating unit 101 and the discharging heat-releasing unit 302 in the embodiment of the present invention, the wet material can absorb part of the heat and have a certain temperature before entering the drying device 200, so that it can be dried more quickly in the drying device 200, reducing the steam amount and drying time used for drying the wet material, shortening the production cycle, and the discharging heat-releasing unit 302 can output the heat and then discharge the dried material.

[0053] Exemplarily, such as Figure 1As shown, the embodiment of the present invention further includes a controllable valve 900. The condensate outlet of the drying device 200 is communicated with the condensate inlet of the steam conversion device 400 through the controllable valve 900. The refrigerant temperature adjustment assembly 800 further includes a temperature sensing assembly 1200 and a control device electrically connected to the temperature sensing assembly 1200 and the controllable valve 900. The temperature sensing assembly 1200 is used to detect the refrigerant temperature at the outlet of the heat absorption chamber of the feeding assembly 100.

[0054] During specific implementation, when the temperature sensing assembly 1200 detects that the refrigerant temperature at the outlet of the heat absorption chamber of the feeding assembly 100 is higher than the set temperature, for example, 40 °C, it indicates that the amount of condensate entering the refrigerant temperature adjustment assembly 800 is excessive. At this time, the controller can be used to control the opening of the controllable valve to become larger, so that the flow rate of the condensate directly entering the steam conversion device 400 is larger, and the flow rate of the condensate directly entering the refrigerant temperature adjustment assembly 800 is smaller, thereby adjusting the temperature of the refrigerant flowing out of the refrigerant temperature adjustment assembly 800 to become lower, and further reducing the temperature of the refrigerant entering the sandwich layer of the feeding assembly.

[0055] When the temperature sensing assembly 1200 detects that the refrigerant temperature at the outlet of the heat absorption chamber of the feeding assembly 100 is lower than the set temperature, for example, 40 °C, it indicates that the amount of condensate entering the refrigerant temperature adjustment assembly 800 is too low. At this time, the controller can be used to control the opening of the controllable valve to become smaller, so that the flow rate of the condensate directly entering the steam conversion device 400 is smaller, and the flow rate of the condensate directly entering the refrigerant temperature adjustment assembly 800 is larger, thereby adjusting the temperature of the refrigerant flowing out of the refrigerant temperature adjustment assembly 800 to increase, and further increasing the temperature of the refrigerant entering the sandwich layer of the feeding assembly 100.

[0056] Exemplarily, as Figure 1 shown, the drying system of the embodiment of the present invention further includes a multi-stage flash evaporation unit 1300 communicated with the condensate inlet of the steam conversion device 400. The outlet of the controllable valve 900 is communicated with the condensate inlet of the multi-stage flash evaporation unit 1300. The steam outlet of the multi-stage flash evaporation unit 1300 is communicated with the steam inlet of the drying device 200 through the steam compression device 500. It should be understood that the temperature at the condensate outlet of the multi-stage flash evaporation unit 1300 is about 95 °C. For the convenience of steam utilization, when the drying system of the embodiment of the present invention includes a multi-stage flash evaporation unit 1300, the heating device 600 can be arranged on the multi-stage flash evaporation unit 1300 with a smaller volume. Before starting up, water is placed in the multi-stage flash evaporation unit. At this time, the power consumption generated during startup can be further reduced.

[0057] In specific implementation, the above-mentioned multi-stage flash evaporation unit 1300 can first flash the high-temperature condensed water discharged from the drying device 200. The water vapor after flashing directly enters the steam compression device 500 for compression and temperature increase, and then is transported to the drying device 200 to dry the wet material. At the same time, the temperature of the condensed water after flashing in the multi-stage flash evaporation unit 1300 decreases, and then it is transported to the steam conversion device 400. By setting the multi-stage flash evaporation unit 1300 in the embodiment of the present invention, it is possible to avoid the high temperature of the condensed water discharged from the drying device 200 from damaging the heat transfer temperature difference of the steam conversion device 400.

[0058] Exemplarily, the condensed water outlet of the above-mentioned multi-stage flash evaporation unit 1300 is also communicated with the steam outlet of the steam compression device 500. When the steam temperature at the steam outlet of the steam compression device 500 is greater than 140 °C, the condensed water discharged from the multi-stage flash evaporation unit 1300 can be used as the steam desuperheating water at the steam outlet of the steam compression device 500 to desuperheat the steam in or at the outlet of the steam compression device 500.

[0059] Exemplarily, as Figure 1 shown, the multi-stage flash evaporation unit includes a first flash evaporation unit 1301 and a second flash evaporation unit 1302. The liquid inlet of the first flash evaporation unit 1301 is communicated with the condensed water outlet of the drying device 200. The liquid outlet of the first flash evaporation unit 1301 is communicated with the liquid inlet of the second flash evaporation unit 1302. The steam outlet of the first flash evaporation unit 1301 is communicated with the inlet of the steam compression device 500. The liquid inlet of the second flash evaporation unit 1302 is communicated with the liquid inlet of the steam conversion device 400. The steam outlet of the second flash evaporation unit 1302 is communicated with the inlet of the steam compression device 500.

[0060] In specific implementation, the above-mentioned first flash evaporation unit 1301 can first flash the high-temperature condensed water discharged from the drying device 200. The water vapor after flashing directly enters the steam compression device 500 for compression and temperature increase, and then is transported to the drying device 200 to dry the wet material. The condensed water remaining after the first flash evaporation unit 1301 flashes the high-temperature condensed water discharged from the drying device 200 can be transported to the second flash evaporation unit 1302, and the second flash evaporation unit 1302 continues to flash. The gas after flashing directly enters the steam compression device 500 for compression and temperature increase. A part of the remaining condensed water after flashing is transported to the steam conversion device 400 for heat exchange, and a part is transported to the steam compression device 500 to cool the steam. It should be understood that a temperature monitoring component can be set at the outlet of the steam compression device 500. When the steam temperature in the steam compression device 500 is greater than the set temperature, for example, 140 °C, the condensed water in the steam conversion device or the multi-stage flash evaporation unit is controlled to be transported to the inlet of the steam compression device 500. It should be understood that the introduction position of the steam desuperheating water can be set at a suitable position in the system according to actual needs. For example: the addition position of the desuperheating water can be set by the compressor manufacturer.

[0061] In an alternative embodiment, as Figure 1 shown, the drying system of the embodiment of the present invention further includes a gas-liquid separation device 1400. The waste liquid outlet of the steam conversion device 400 is sequentially connected to the refrigerant temperature adjustment assembly 800 through the gas-liquid separation device 1400 and the waste liquid pipeline 1500. It should be understood that the waste liquid here is dirty condensate, and the temperature of the dirty condensate is higher than the temperature of the refrigerant discharged from the heat release cavity of the discharge assembly 300.

[0062] Specifically, in implementation, the second steam in the above-mentioned steam conversion device 400 exchanges heat with the condensate, and the second steam condenses into waste liquid. The waste liquid and a small amount of non-condensable gas enter the gas-liquid separation device 1400 for gas-liquid separation. The separated non-condensable gas is discharged to the treatment device for treatment by suction of a blower, and the separated waste liquid is discharged into the refrigerant temperature adjustment assembly 800 through the waste liquid pipeline 1500 to further heat the refrigerant discharged from the heat release cavity of the discharge assembly 300, so that the temperature of the refrigerant further increases. In addition, the cooled dirty condensate can be used to wash the non-condensable gas, avoiding the use of fresh water and reducing the sewage discharge.

[0063] Specifically, in implementation, the above-mentioned waste liquid pipeline 1500 discharges the waste liquid to the first refrigerant temperature adjustment device 801. At this time, the refrigerant discharged from the heat release cavity of the discharge assembly 300 can enter the first refrigerant temperature adjustment device 801, and its temperature is further increased by using the waste liquid and then discharged to the second refrigerant temperature adjustment device 802. Then, the condensate discharged from the drying device to the second refrigerant temperature adjustment device 802 is used to continue to increase the temperature to obtain the heated refrigerant. Thereafter, the heated refrigerant is introduced into the interlayer of the feeding assembly to preheat the wet material. The dirty condensate in the first refrigerant temperature adjustment device 801 and the condensate in the second refrigerant temperature adjustment device 802 are used to heat the refrigerant discharged from the heat release cavity of the discharge assembly 300 so that the refrigerant has a higher temperature to preheat the wet material, thereby reducing the steam consumption during the drying of the drying device 200, realizing the cascade utilization of energy, and saving the power consumption of the steam compression device.

[0064] In another example, Figure 2 shows the process flow diagram of the second drying system of the embodiment of the present invention. As Figure 2As shown in the figure, the second drying system according to the embodiment of the present invention includes: a feeding assembly 100, a drying device 200, a discharging assembly 300, a steam conversion device 400, a steam compression device 500, a heating device 600, a refrigerant container 700, a refrigerant temperature adjustment assembly 800, an automatic control valve 1000, a temperature sensor 1100, and a waste liquid pipeline 1500. Among them, the feeding assembly 100 includes a feeding preheating unit 101 and a sealed feeding unit 102, the discharging assembly 300 includes a sealed discharging unit 301 and a discharging heat release unit 302, and the refrigerant temperature adjustment assembly 800 includes a first refrigerant temperature adjustment device 801 and a second refrigerant temperature adjustment device 802.

[0065] On this basis, the difference between the second drying system according to the embodiment of the present invention and Figure 1 the first drying system is that the steam conversion device 400 of the second drying system can be a steam scrubbing tower, and the steam scrubbing tower is used to purify the second steam and then transport it to the steam compression device 500, so that the impurities in the second steam entering the steam compression device are reduced, and further the impurities remaining in the whole system are reduced, improving the service life of the drying system. At the same time, the second drying system can also not be provided with a multi-stage flash evaporation unit, a controllable valve 900, and a temperature sensing assembly 1200. The condensed water discharged from the drying device 200 is directly used to exchange heat through the refrigerant temperature adjustment device and then transported to the steam scrubbing tower, and the waste liquid outlet of the steam scrubbing tower is communicated with the refrigerant temperature adjustment assembly through the waste liquid pipeline.

[0066] The embodiment of the present invention also provides a drying method, which includes: using the feeding assembly to transport wet materials to the drying device, and the drying device uses the first steam to dry the wet materials to obtain dry materials. Among them, during the process of the drying device using the first steam to dry the wet materials, the moisture in the wet materials is discharged to the steam conversion device in the form of the second steam. After the first steam dries the wet materials, at least part of it is discharged to the steam conversion device in the form of condensed water. The condensed water absorbs the heat of the second steam in the steam conversion device and is converted into the third steam. The steam compression device is used to compress and heat up the third steam, and the compressed and heated third steam is introduced into the drying device.

[0067] Exemplarily, when the above drying system includes a refrigerant container and a refrigerant temperature adjustment assembly, the drying method according to the embodiment of the present invention further includes: using the temperature adjustment assembly to perform heat exchange between the refrigerant provided by the refrigerant container and the condensed water, so that the refrigerant is preheated by the condensed water, and the condensed water is cooled by the refrigerant. The cooled condensed water is introduced into the steam conversion device, and the preheated wet materials in the feeding assembly are heated by the heated refrigerant.

[0068] For example, when the above-mentioned drying system includes a controllable valve, a temperature sensing component, and a control device electrically connected to the temperature sensing component and the controllable valve, the drying method further includes: when the refrigerant temperature at the outlet of the heat absorption chamber of the feeding component is greater than the preset temperature, controlling the controllable valve to adjust the flow rate of the condensed water entering the refrigerant temperature adjustment component to decrease; when the refrigerant temperature at the outlet of the heat absorption chamber of the feeding component is less than the preset temperature, controlling the controllable valve to adjust the flow rate of the condensed water entering the refrigerant temperature adjustment component to increase.

[0069] In an optional manner, in the drying system of the embodiment of the present invention, water pumps can be provided in any condensed water pipeline and refrigerant pipeline for transporting condensed water or refrigerant.

[0070] As can be seen from the above, the embodiment of the present invention can use the feeding component to transport wet materials to the drying device in a sealed manner. The drying device uses the first steam to dry the wet materials to obtain dry materials. The discharging component is used to output the dry materials from the drying device in a sealed manner and cool down the dry materials at the same time, recovering the waste heat of the dry materials. The refrigerant cycle is used to recover the waste heat of the dry materials, the waste liquid of the steam conversion device (the evaporation condensate of the wet materials), and the condensate waste heat of the drying device in sequence, for preheating the wet materials.

[0071] In summary, for the drying system of the embodiment of the present invention, only after the water in the steam conversion device 400 is physically heated to form water vapor after starting up, and then compressed and heated by the steam compression device 500 and introduced into the drying device to dry the wet materials, can the recovery and utilization of the second steam in the wet materials be realized. Therefore, it is not necessary to continuously heat the drying system, reducing the power consumption and saving the production cost. At the same time, the drying system of the embodiment of the present invention realizes a closed-loop system. Both the condensed water and the refrigerant can be recycled. The refrigerant water is used as a heat recovery medium to recover the waste heat of the dry materials and the dirty condensed water to preheat the wet materials. The second steam generated during the drying process of the wet materials can also be continuously discharged to the steam conversion device for recycling. During the operation of the entire system, only a small amount of power consumption will be generated when the steam conversion device starts up and when the steam compression device compresses and heats up. The rest of the energy comes from the system itself, greatly reducing the energy consumption and power consumption of the drying system and saving the production cost.

[0072] Both drying systems of the embodiment of the present invention adopt sealed feeding and discharging, the chamber temperature of the drying device is about 100 °C, the steam pressure is equal to the ambient air pressure, no air is mixed in, the heat loss of the non-condensable gas discharged from the drying device is extremely small, the waste heat of the dry materials and the dirty condensed water is recovered through the waste heat recovery system for preheating the wet materials, and the waste heat recovery ratio is about 67% of the heat carried by the dry materials and the dirty condensed water. All equipment and pipelines are insulated to reduce the system heat dissipation to the lowest level. Through the above measures, the total energy discharged from the system can be basically balanced with the total energy input into the system by the steam compression device.

[0073] In an embodiment of the present invention, taking the drying of sludge with a water content of 80% to a water content of 40% as an example, the energy balance is shown in Table 1.

[0074] Table 1: Energy balance (based on drying 1 kg of wet sludge)

[0075] Item Unit (kj / kg) Surplus heat quantity 281.9 Surplus heat quantity in dry sludge 59.0 Surplus heat quantity in sewage condensate 222.9 Surplus heat recovery quantity (heat consumption for wet sludge preheating) 188.4 Recover heat from dry sludge 36.9 Recover heat from sewage condensate 151.5 Unused surplus heat quantity 93.5 Heat loss of dry sludge 22.1 Heat loss of sewage condensate 71.4 Heat loss due to non-condensable gas discharged from drying device and system heat dissipation 132.9 Total heat quantity discharged from system 226.4 Total energy input to steam compressor system (with a margin) 310.8

[0076] When the drying system in an embodiment of the present invention uses a paddle drying device or a vertical disk drying device as the drying device 200, the power consumption index for drying 1 ton of sludge is shown in Table 2.

[0077] Table 2: Power consumption index for drying 1 ton of sludge

[0078]

[0079]

[0080] When the drying system in an embodiment of the present invention uses a paddle drying device or a vertical disk drying device as the drying device 200, the power consumption index for evaporating 1 ton of water is shown in Table 3.

[0081] Table 3: Power consumption index for evaporating 1 ton of water

[0082]

[0083] For the low-temperature heat pump dehumidification drying technology, paddle drying equipment, vertical disk drying equipment or mid-temperate drying equipment in the prior art, the energy consumption index for drying sludge with a water content of 80% to a water content of 40% is shown in Table 4.

[0084] Table 4: Power consumption index for drying 1 ton of sludge and 1 ton of water in the prior art

[0085] Energy consumption index Unit Low-temperature heat pump Agitator type Vertical disc Mid-temperate zone type Power consumption for drying 1t of sludge kWh 168-235 34.5 8.6 35.3 Steam consumption for drying 1t of sludge t - 0.84 0.84 0.95 Power consumption for evaporating 1t of water kWh 250-350 51.8 12.9 53.0 Steam consumption for evaporating 1t of water t 0 1.27 1.27 1.43

[0086] Figure 3 The sludge drying energy balance diagram of the drying system in an embodiment of the present invention for daily processing 100 tons of wet sludge is shown. Figure 4 The energy balance diagram of the waste heat recovery system of the drying system in an embodiment of the present invention for daily processing 100 tons of wet sludge is shown.

[0087] As can be seen from the above table, when the drying system of the embodiment of the present invention uses a paddle drying device as the drying apparatus, the total power consumption for drying 1 ton of sludge is 134 kWh, and the total power consumption for evaporating 1 ton of water is 201 kWh. When using a vertical disk drying device as the drying apparatus, the total power consumption for drying 1 ton of sludge is 103 kWh, and the total power consumption for evaporating 1 ton of water is 155 kWh. In the prior art, when using the low-temperature heat pump dehumidification drying technology, the total power consumption for drying 1 ton of sludge is 168 kWh - 235 kWh, and the total power consumption for evaporating 1 ton of water is 250 kWh - 350 kWh. Other drying methods all require the use of steam, and the total energy consumption for drying one ton of sludge is higher than 650 kWh, and the total energy consumption for evaporating one ton of water is higher than 970 kWh.

[0088] As can be seen from the above table and Figure 3 、 Figure 4 it can be known that the steam loss of the drying system of the embodiment of the present invention is far less than that of the prior art, greatly reducing the steam energy consumption. By adopting the heat pump technology, it consists of a drying apparatus, a steam conversion device, a heat medium steam compression device, a steam system, a secondary steam and sewage condensate system, and a waste heat recovery system, realizing a closed-loop system. The secondary steam, condensate water, and refrigerant can all be recycled, greatly reducing the heat loss and saving the production cost.

[0089] The drying system of the embodiment of the present invention mainly adopts the heat pump technology, the continuous drying technology in a sealed state, the waste heat recovery of the discharged material and the preheating of the fed material. The latent heat of vaporization of the water evaporated from the material is recovered by the heat pump system and reused for material drying. The waste heat in the condensate water and the dry material is recovered by the heat exchange device and used for preheating the wet material, so that the heat loss of the system is balanced with the electric energy input by the steam compressor. In the heat pump system, the steam compressor is the heat pump, water is the heat medium, the drying apparatus is the condenser, and the steam conversion device of the exhaust steam (secondary steam) of the drying apparatus and the heat medium water is the evaporator. In the evaporator, the heat medium water absorbs heat and vaporizes, and after being compressed and heated by the steam compressor, it is sent to the sludge drying apparatus for use. The high-temperature heat medium water after condensation is cooled by heat exchange in the waste heat recovery system and then returns to the evaporator to absorb heat and vaporize, and so on in a cycle to achieve energy balance.

[0090] The above are only specific embodiments of the present invention. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and the accompanying drawings are only exemplary descriptions of the present invention defined by the appended claims, and are considered to cover any and all modifications, variations, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the intention of the present invention includes these changes and modifications. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the said claims.

Claims

1. A drying system, characterized in that, Comprising: A feed component, a drying device, a discharge component, a steam conversion device, and a steam compression device. The steam conversion device is a heat exchange device or a washing device. The feed component is communicated with the feed inlet of the drying device, and the discharge component is communicated with the discharge outlet of the drying device; The steam outlet of the drying device is communicated with the steam inlet of the steam conversion device. The steam outlet of the steam conversion device is communicated with the steam inlet of the drying device through the steam compression device. The condensate outlet of the drying device is communicated with the condensate inlet of the steam conversion device; The feed component and the discharge component are respectively sealed with the drying device, and the steam pressure in the drying chamber of the drying device is the same as the external atmospheric pressure; The drying system further includes a refrigerant container and a refrigerant temperature adjustment component. The condensate outlet of the drying device is communicated with the condensate inlet of the steam conversion device through the refrigerant temperature adjustment component. The refrigerant temperature adjustment component is used to adjust the temperature of the refrigerant discharged from the refrigerant container and the temperature of the condensate entering the steam conversion device; The drying system further includes: a controllable valve. The condensate outlet of the drying device is communicated with the condensate inlet of the steam conversion device through the controllable valve. The drying system further includes a temperature sensing component and a control device electrically connected to the temperature sensing component and the controllable valve. The temperature sensing component is used to detect the temperature of the refrigerant at the outlet of the heat absorption chamber of the feed component. The control device is used to control the opening of the controllable valve to increase when the refrigerant temperature is greater than a preset temperature, so that the flow rate of the condensate directly entering the steam conversion device is larger and the flow rate of the condensate directly entering the refrigerant temperature adjustment component is smaller. The control device is used to control the opening of the controllable valve to decrease when the refrigerant temperature is less than the preset temperature, so that the flow rate of the condensate directly entering the steam conversion device is smaller and the flow rate of the condensate directly entering the refrigerant temperature adjustment component is larger.

2. The drying system according to claim 1, characterized in that, The temperature of the refrigerant at the outlet of the heat absorption chamber of the feed component is lower than the temperature of the dry material in the discharge component. When the steam conversion device is a heat exchange device, the temperature of the condensate inlet of the steam conversion device is lower than the temperature of the steam inlet of the steam conversion device.

3. The drying system according to claim 2, characterized in that, The outlet of the refrigerant container is sequentially communicated with the inlet of the refrigerant container through the heat absorption chamber of the discharge component, the refrigerant temperature adjustment component, and the heat absorption chamber of the feed component.

4. The drying system according to claim 3, characterized in that, The drying system further includes a multi-stage flash evaporation unit communicated with the condensate inlet of the steam conversion device. The outlet of the controllable valve is communicated with the condensate inlet of the multi-stage flash evaporation unit. The steam outlet of the multi-stage flash evaporation unit is communicated with the steam inlet of the drying device through the steam compression device.

5. The drying system according to any one of claims 1 to 4, characterized in that When the steam conversion device is a heat exchange device, the drying system further includes a gas-liquid separation device. The waste liquid outlet of the steam conversion device is sequentially communicated with the refrigerant temperature adjustment component through the gas-liquid separation device and a waste liquid pipeline. When the steam conversion device is a washing device, the waste liquid outlet of the steam conversion device is communicated with the refrigerant temperature adjustment component through the waste liquid pipeline.

6. A drying method, characterized in that, Applied to the drying system according to any one of claims 1 to 5, the drying method includes: Using a feeding assembly to convey wet materials to a drying device in a sealed manner, the drying device drying the wet materials with first steam to obtain dry materials, and using a discharging assembly to output the dry materials from the drying device in a sealed manner; Wherein, during the process of the drying device drying the wet materials with first steam, the moisture in the wet materials is discharged to a steam conversion device in the form of second steam, and after drying the wet materials, at least part of the first steam is discharged to the steam conversion device in the form of condensed water; When the steam conversion device is a heat exchange device, the condensed water absorbs the heat of the second steam in the heat exchange device and is converted into third steam. When the steam conversion device is a washing device, the condensed water flashes and vaporizes in the washing device and is jointly converted into third steam with the second steam. Using a steam compression device to compress and heat up the third steam, and introducing the compressed and heated third steam into the drying device, and the steam pressure in the drying chamber of the drying device is the same as the external atmospheric pressure.

7. The drying method according to claim 6, characterized in that, When the drying system includes a refrigerant container and a refrigerant temperature adjustment assembly, the drying method further includes: Using the refrigerant provided by the refrigerant container to cool the dry materials in the discharging assembly to obtain heated refrigerant; Using the temperature adjustment assembly to perform heat exchange between the waste liquid discharged from the steam conversion device and the condensed water, so that the heated refrigerant is further heated by the waste liquid and the condensed water, the waste liquid and the condensed water are cooled by the refrigerant, and the cooled waste liquid is discharged into an external sewage treatment system; Introducing the cooled condensed water into the steam conversion device, and using the further heated refrigerant to preheat the wet materials in the feeding assembly.

8. The drying method according to claim 7, characterized in that, When the drying system includes a controllable valve, a temperature sensing assembly, and a control device electrically connected to the temperature sensing assembly and the controllable valve, the drying method further includes: When the refrigerant temperature at the outlet of the heat absorption chamber of the feeding assembly is greater than a preset temperature, controlling the controllable valve to adjust the flow rate of the condensed water entering the refrigerant temperature adjustment assembly to decrease; When the refrigerant temperature at the outlet of the heat absorption chamber of the feeding assembly is less than a preset temperature, controlling the controllable valve to adjust the flow rate of the condensed water entering the refrigerant temperature adjustment assembly to increase.

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