A low temperature section dryer

Abstract

A low-temperature section dryer includes a closed box body and a belt-type wet material transmission mechanism, the transmission mechanism includes a transmission belt and a pulley; at least two layers of transmission mechanisms are arranged in the box body, and a guide inclined plate is arranged between them; a wet material or sludge feeding port is arranged at the top of the box body, corresponding to the beginning of the upper transmission mechanism, and a wet material or sludge discharge port is arranged at the bottom of the box body, corresponding to the end of the lower transmission mechanism; a waste gas / smoke flow channel parallel to the transmission mechanism is arranged below each layer of the transmission mechanism along its length direction, one end of the upper and lower flow channels is connected and connected by a connecting pipe to form a U shape, and the other end is provided with a waste gas / smoke gas outlet and a waste gas / smoke gas inlet; the upper and lower space in the upper flow channel in the box body forms a U-shaped hot air medium channel, and the upper layer is provided with a hot air outlet and the lower layer is provided with a hot air inlet; a steam chamber is arranged on the top surface of the box body. The temperature and moisture content of the outlet air of the dryer are increased, and the drying capacity and drying efficiency of the unit drying medium (air) are improved.

Description

Technical Field

[0001] The invention relates to the technical field of sludge drying and sludge treatment, and in particular discloses a low-temperature section dryer. Background Art

[0002] Sludge thermal drying technology is a treatment process that uses heat energy to quickly remove moisture from sludge. The removal of moisture mainly goes through two processes: evaporation and diffusion. The evaporation process refers to the vaporization of moisture on the surface of the material, and the diffusion process refers to the mass transfer process closely related to vaporization.

[0003] Sludge thermal drying can be divided into two categories according to the contact mode between the heat medium and the sludge. One is direct thermal drying, that is, the application of thermal convection technology. The belt dryer and fluidized bed type are widely used in domestic projects. The other is indirect thermal drying, that is, the application of heat conduction technology. The more widely used and mature ones include disc type, thin layer type, paddle type, etc. According to the operating temperature, it can be divided into high temperature drying and low temperature drying. At the same time, Suez's thin layer + belt dryer two-stage type also has corresponding applications.

[0004] The current traditional mainstream high-temperature drying process uses three types of sludge dryers: rotary type, swirl flash type and belt type.

[0005] The single-pass rotary sludge dryer is widely used in the Japanese sludge drying industry. This equipment has an antenna-shaped crushing rod in the sludge drying cylinder, which rotates at a speed of 200-400rpm to crush large sludge and improve the drying efficiency. When using 1000℃ hot air for sludge drying, the rotary water evaporation rate can reach 5000kg / h.

[0006] ABB Raymond of the United States proposed a cage-type crushing cyclone flash sludge drying device, which uses a cage-type crushing device to crush the sludge, suspend the sludge particles in the hot air, and quickly dry the sludge by increasing turbulence and residence time. This drying device can achieve a water vapor evaporation rate of 8000kg / h.

[0007] Belt-type sludge dryers are mainly divided into three types: open, semi-open and closed. Among them, the closed belt sludge drying device, the main principle is to use hot air to heat the sludge transmitted through the belt to achieve the purpose of drying.

[0008] Low-temperature sludge drying is a relatively new drying technology. Compared with high-temperature drying, it has the advantages of energy saving, safety and less pollutant release. Low-temperature sludge drying mainly uses solar energy and low-grade waste heat energy such as waste heat flue gas as heat sources, which can significantly reduce the energy consumption of sludge drying. With low-temperature drying, the amount of pollutants released during the sludge drying process is relatively small, which greatly reduces the pressure on tail gas treatment. At present, the more common low-temperature drying technology is based on heat pump drying technology, as well as jet drying, solar drying, etc.

[0009] During heat pump drying, the air circulates in a closed loop between the drying chamber and the heat pump dryer. The refrigeration system of the heat pump dryer is used to cool and dehumidify the hot and humid air from the drying chamber. When the hot and humid air flows through the heat pump evaporator, the water vapor in it is condensed by cooling and discharged as liquid water. The refrigerant absorbs the heat of the air and changes from liquid to gas (for example, if the heat pump working fluid pair is LiBr / H2O, the low-pressure water vapor evaporated by absorbing the heat of the air). In the condenser, the internal high-pressure refrigerant releases heat due to condensation, and the dehumidified dry cold air is heated to hot dry air, which returns to the drying chamber. The high-pressure refrigerant flowing out of the condenser is reduced in pressure by the expansion valve and flows into the evaporator to continue the next cycle.

[0010] Jet drying technology uses the "shock wave" principle to generate supersonic airflow through high-speed fans, accelerate saturated wet air to the supersonic range, generate shock wave vibrations in the air, and cause saturated water in the air to oscillate out. Jet drying dries 80% of wet mud to less than 60% per ton, with a comprehensive power consumption of about 35-45kw / h. Low-temperature sludge jet drying technology must be equipped with an efficient dust collection device, otherwise the dust carried by the exhaust gas will cause serious pollution, so the equipment cost is relatively high. In addition, the flow resistance of its jet drying system is large and the power consumption is large.

[0011] In the Suez two-stage drying process, the sludge first passes through a thin layer dryer, and is dried to a moisture content of 55%-65%. It is then cut into strips by a forming machine and then enters a belt dryer for drying. The belt dryer uses circulating air for drying, and the mixed gas is condensed (water vapor condenses) and reheated (using a stage of tail gas and boiler steam) for recycling. This technology greatly improves the energy utilization efficiency compared to a single-stage dryer. Its low-temperature drying method is the same as the heat pump-based dehumidification method, and the circulating fan has a high power consumption.

[0012] In the above-mentioned low-temperature drying technologies, air is in contact with sludge in the dryer, acting as both a material carrier for water removal and an energy carrier for heat input. However, since air has a very small specific heat capacity and can carry very limited amounts of heat, the circulating air volume in the above-mentioned conventional low-temperature drying systems is relatively large, resulting in large power consumption of the circulating fan, etc., which increases the energy consumption of the system.

[0013] In view of the above problems, the inventors have proposed a sludge drying device that utilizes low-temperature waste heat to make full use of the low-grade thermal energy containing a large amount of water vapor in the dryer exhaust gas or flue gas, and integrate the reheating measures for the air medium in the belt low-temperature dryer to improve the moisture carrying capacity of the air. At the same time, the equipment such as cooling, reheating, and pressurized circulation of wet air in the conventional belt dryer system is eliminated, thereby improving the drying capacity of the unit drying medium (odor achieved in the air / drying room, hereinafter collectively referred to as air); reducing operating costs such as power consumption, and promoting the development of the sludge treatment industry. Summary of the invention

[0014] The present invention provides a low-temperature section dryer, which aims to solve the technical problem that in the existing low-temperature drying technology, air is in contact with sludge in the dryer, the specific heat capacity of air is very small, and the heat it carries is very limited, resulting in a relatively large circulating air volume in the conventional low-temperature drying system, which leads to a large power consumption of the circulating fan, etc., and increases the energy consumption of the system. The present invention is committed to using the low-quality heat in the exhaust gas of the heat conduction dryer or the flue gas of the boiler (containing a large amount of water vapor) to dehydrate and dry the wet sludge, and at the same time condense the water vapor in the exhaust gas, thereby improving the drying efficiency and reducing energy consumption.

[0015] The technical solution of the present invention is as follows:

[0016] A low-temperature section dryer comprises a closed box body and a belt-type wet material transmission mechanism, wherein the transmission mechanism comprises a transmission belt and a pulley; at least two layers of the transmission mechanism are arranged in the box body, and a guide inclined plate is arranged between the two layers of the transmission mechanism, which receives the material coming down from the end of the transmission belt of the upper transmission mechanism and guides it onto the beginning of the transmission belt of the lower transmission mechanism; a wet material or sludge feeding port is arranged at one end of the top of the box body corresponding to the beginning of the transmission belt of the upper transmission mechanism, and a wet material or sludge discharging port is arranged at the bottom of the box body corresponding to the end of the transmission belt of the lower transmission mechanism for receiving the wet material discharged;

[0017] A waste gas / smoke flow channel parallel to the transmission mechanism along its length is provided below each layer, and the waste gas / smoke flow channel is a closed cavity structure, and a plurality of transversely arranged heat transfer pipes are fixed on the outer wall of the cavity structure, and the two ends of the heat transfer pipes are respectively inserted into the cavity structure, and the cavity structure of the upper layer is connected with one end of the cavity structure of the lower layer through a connecting pipe to form a U shape, and the end face of the end of the cavity structure of the lower layer on one side of the connecting pipe is installed on the side wall of the box body for sealing; the other end of the cavity structure of the upper layer is provided with a waste gas / smoke gas outlet installed on the side wall of the box body and on the side of the wet material or sludge feed port, and the other end of the cavity structure of the lower layer is provided with a waste gas / smoke gas inlet installed on the bottom wall of the box body and on the same side of the waste gas / smoke gas outlet;

[0018] The space above and below the upper circulation channel in the box body forms a U-shaped hot air medium channel; the upper end of the U-shaped hot air medium channel is provided with a hot air outlet installed on the side wall of the box body and arranged at the upper part of the same side as the exhaust gas / smoke gas outlet, and the lower end thereof is provided with a hot air inlet installed on the side wall of the box body and arranged at the lower part of the same side as the exhaust gas / smoke gas outlet;

[0019] The steam chamber on the top surface of the box body is a hollow metal sandwich structure, a steam / hot water medium inlet is arranged at one end of the sandwich and is installed on the top surface of the box body, and a steam / hot water medium outlet is arranged at the other end and is installed on the side wall of the box body and arranged on the same side as the hot air outlet. Steam / hot water medium is introduced into the sandwich.

[0020] The connecting pipes are provided in two numbers and are located on both sides of the circulation channel and the transmission mechanism; the waste gas / smoke gas inlet of the lower cavity is provided in two numbers and is located on both sides of the wet material or sludge discharge port.

[0021] A condensate collection and diversion port is arranged on the cavity structure of the exhaust gas / smoke flow channel to connect the condensate diversion pipe outside the box body to lead into the wastewater tank.

[0022] Effects of the Invention

[0023] The present invention discloses a low-temperature section dryer, which utilizes the waste gas or flue gas containing a large amount of water vapor in the heat conduction type high-temperature section dryer to continuously heat the air in the low-temperature section dryer, thereby utilizing the low-temperature waste heat in the waste gas / flue gas and increasing the temperature and moisture content of the air at the outlet of the dryer, thereby improving the drying capacity and drying efficiency of the unit drying medium (air); at the same time, the equipment such as cooling, reheating and pressurizing circulation of wet air in the conventional belt dryer system is omitted, thereby reducing the operating costs such as power consumption; the drying medium utilized can be the conventional exhaust deodorization gas in the drying room; it can be used in new or renovated projects for sludge treatment, and has good application value and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the structure of the low temperature section dryer of the present invention.

[0025] Figure 2 for Figure 1 Cross-sectional view,

[0026] Figure 3 This is a schematic diagram of the connection and working process of the present invention in a drying system.

[0027] Figure 4 This is a schematic diagram of the plan layout of the drying system of the present invention.

[0028] Figure 5It is a schematic diagram of the cross-sectional arrangement of the drying system of the present invention.

[0029] Description of the accompanying drawings:

[0030] Box body 101, wet material or sludge feed inlet 1011, wet material or sludge discharge port 1012, transmission mechanism 102, conveyor belt 1021, conveyor belt starting end 10211, conveyor belt end 10212, guide inclined plate 1022, exhaust gas / smoke flow channel 103, heat transfer heat pipe 1031, connecting pipe 1032, end head 1033, exhaust gas / smoke gas inlet 1034, exhaust gas / smoke gas outlet 1035, condensate collection guide port 1036, hot air medium channel 104, hot air inlet 1041, hot air outlet 1042, metal sandwich structure 105, steam / hot water medium inlet 1051, steam / hot water medium outlet 1052, molding machine 106.

[0031] Figure 3 Description of the drying system numbers: low temperature section dryer 1, high temperature section dryer 2, cyclone dust collector 3, air heat exchanger 4, air heat exchanger gas inlet 401, condenser 5, exhaust fan 51, odor treatment system 6, waste water tank 7, deodorization system 8, washing tower 81, biological filter 82, air pump 83, buffer crushing bin 9, screw conveyor 10, dry mud storage bin 11, drying room 12; DETAILED DESCRIPTION

[0032] See also Figure 1 , 2 As shown, a low-temperature section dryer of the present invention comprises a closed box body and a belt-type wet material transmission mechanism, wherein the transmission mechanism comprises a transmission belt and a pulley; at least two layers of the transmission mechanism 102 are arranged in the box body 101, and a guide inclined plate 1022 is arranged between the two layers of the transmission mechanism to receive the material coming down from the end of the transmission belt 1021 of the upper transmission mechanism and introduce it onto the starting end 10211 of the transmission belt of the lower transmission mechanism; a wet material or sludge feeding port 1011 is arranged at one end of the top of the box body corresponding to the starting end 10211 of the transmission belt of the upper transmission mechanism, and in addition, a wet material or sludge discharging port 1012 for receiving the wet material discharged therefrom is arranged at the bottom of the box body corresponding to the end 10212 of the transmission belt of the lower transmission mechanism;

[0033] Below each layer of the transmission mechanism, there is a waste gas / smoke flow channel 103 parallel to the transmission mechanism and along its length direction. The waste gas / smoke flow channel is a closed cavity structure. A plurality of transversely arranged heat transfer pipes 1031 are fixed on the outer wall of the cavity structure, and the two ends of the heat transfer pipes are respectively inserted into the cavity structure. The cavity structure of the upper layer is connected to one end of the cavity structure of the lower layer through a connecting pipe 1032 to form a U shape. The end face of the end of the cavity structure of the lower layer on one side of the connecting pipe is arranged It is installed on the side wall of the box and closed; the other end of the upper cavity structure is provided with a waste gas / smoke gas outlet 1035 installed on the side wall of the box and on the side of the wet material or sludge feed port, and the other end of the lower cavity structure is provided with a waste gas / smoke gas inlet 1034 installed on the bottom wall of the box and on the same side of the waste gas / smoke gas outlet 1035; both ends of the heat transfer heat pipe 1031 are fixed on the cavity structure, and the two end heads are deeply inserted into the interior of the cavity structure to increase the heat transfer area.

[0034] The space above and below the upper circulation channel in the box body forms a U-shaped hot air medium channel 104; the upper end of the U-shaped hot air medium channel is provided with a hot air outlet 1042 installed on the side wall of the box body and arranged on the same side as the exhaust gas / smoke gas outlet 1035, and the lower end thereof is provided with a hot air inlet 1041 installed on the side wall of the box body and arranged on the same side as the exhaust gas / smoke gas outlet 1035;

[0035] The steam cavity is provided on the top surface of the box body as a hollow metal sandwich structure 105, a steam / hot water medium inlet 1051 is provided at one end of the sandwich and is installed on the top surface of the box body, and a steam / hot water medium outlet 1052 is provided at the other end and is installed on the side wall of the box body and arranged on the same side as the hot air outlet 1042. Steam / hot water medium is introduced into the sandwich.

[0036] The connecting pipes are provided in two numbers and are located on both sides of the circulation channel and the transmission mechanism; the waste gas / smoke gas inlet of the lower cavity is provided in two numbers and is located on both sides of the wet material or sludge discharge port.

[0037] A condensate collection guide port 1036 is provided on the cavity structure of the exhaust gas / smoke flow channel to connect the condensate guide pipe outside the box to the waste water tank.

[0038] See also Figure 1 As shown, the wet sludge enters the beginning of the conveyor belt of the upper conveyor mechanism through the top forming machine 106, and falls from the end of the conveyor belt to the beginning of the conveyor belt of the lower conveyor mechanism through the guide inclined plate, and then is transported to the end and unloaded to the wet material or sludge discharge port at the bottom of the box for delivery. The wet sludge is transported through the upper and lower layers to extend the drying time and improve the drying efficiency.

[0039] Under each layer of conveyor belt, there is a closed cavity structure for the flow channel of exhaust gas / smoke. A heat transfer pipe is arranged in the cavity structure. The heat transfer pipe increases the heat transfer area. The exhaust gas / smoke gas inlet is arranged on the side of the lower flow channel. After the exhaust gas enters from the inlet, it enters the upper exhaust gas / smoke flow channel through the connecting pipes on the two sides of the other end, and is led out from the exhaust gas / smoke gas outlet at the other end. At the same time, the condensed liquid in the exhaust gas is discharged through the collection and diversion port of each cavity; the exhaust gas (smoke) is cooled by heat exchange with the air to realize the waste heat utilization. Since the exhaust gas / smoke flow channel is arranged under the conveyor belt in a U-shaped upper and lower structure, the flow stroke of the exhaust gas is extended, the waste heat of the exhaust gas is fully utilized, and the steam in the exhaust gas is fully condensed, the waste heat of the exhaust gas is utilized to the maximum extent, and the drying efficiency is improved. The exhaust gas has a high moisture content and carries a large amount of heat. The large amount of heat released after condensation continuously heats the air medium, thereby improving the drying efficiency.

[0040] A condensate collection guide port 1036 is provided on the cavity structure of the exhaust gas / smoke flow channel to connect the condensate guide pipe outside the box body to lead the condensate into the waste water tank 7 for purification and reuse.

[0041] Above the two exhaust / smoke circulation channels is the channel for hot air of the drying medium. The hot air inlet is set at the bottom wet material or sludge discharge port, and the hot air outlet is set at the top wet material or sludge feed port. The hot air can pass through the conveyor belt in the channel to contact the sludge and take away the moisture in the sludge. The sludge is dried by the hot air. The hot air is continuously heated by the heat transfer heat pipe on the lower side of the channel to improve the moisture absorption capacity, while improving the air's moisture carrying capacity and drying efficiency, reducing energy consumption. Finally, it is discharged from the hot air outlet of the upper channel. The top cover is provided with a steam chamber to prevent the air carrying water vapor from condensing back into the sludge after being cooled at the top. The box is filled with hot air, which is divided into upper and lower U-shaped hot air medium channels by the upper exhaust / smoke circulation channel. The hot air circulates from the lower layer of the hot air medium channel to the upper layer outlet for discharge, extending the residence time of the hot air in the box, so that it is continuously heated by the exhaust / smoke circulation channel and the heat transfer heat pipe, improving the moisture carrying capacity and the drying efficiency.

[0042] Example

[0043] The drying system of the embodiment and implementation of the present invention is as follows Figure 1-4 As shown, the workflow is as follows:

[0044] (1) See Figure 3 The present implementation system is a high and low temperature two-stage sludge drying system, wherein the low temperature stage dryer 1 adopts the device of the present invention. Figure 1The heat source comes from the exhaust heat of the high temperature section dryer 2. The wet sludge first enters the low temperature section dryer 1 for drying. After being sent out of the low temperature section dryer, it is conveyed to the high temperature section dryer 2 on the first floor by a spiral. After reaching the predetermined dryness (generally 65-90%), it is conveyed to the dry sludge storage bin for standby use.

[0045] (2) The waste gas generated by the high-temperature dryer contains a large amount of steam and non-condensable gas. After being dedusted by a cyclone dust collector, it enters the high-efficiency and low-energy consumption low-temperature dryer of the present invention. Most of the steam is condensed in the low-temperature dryer, and then further cooled by an air heat exchanger and condenser before being sent to odor treatment facilities such as the furnace. The condensate is collected and sent to a wastewater treatment facility for treatment.

[0046] (3) After the room deodorization exhaust air is heated in the air exchanger, it enters the low-temperature section dryer of the present invention to absorb heat and moisture, and is continuously heated in the dryer to remove moisture from the sludge, thereby achieving the sludge dehydration and drying effect; the hot and humid air carrying water vapor is led to the roof deodorization system, washed and treated with biological deodorization to meet the standards before being discharged. The specific connection and working process of the drying system are described as follows:

[0047] The present invention implements a high-efficiency sludge drying system for energy cascade utilization, including a closed drying room, and a low-temperature section dryer and a high-temperature section dryer are arranged in the drying room, the drying room 12 includes at least one floor and two floors, the exhaust gas in the high-temperature section dryer 2 located on the first floor is discharged through the exhaust gas discharge pipe, and then enters the cyclone dust collector 3 located on the first floor through the dust removal inlet pipe through the connecting pipeline. After dust removal, it is discharged through the dust removal exhaust pipe, and the dust removal exhaust gas enters the cyclone dust collector 3 located on the second floor through the exhaust gas / smoke gas inlet 1034 through the connecting pipeline. The exhaust gas / smoke flow channel 103 of the low-temperature section dryer 1, most of the steam in the dust removal tail gas is condensed in the low-temperature section dryer, and then discharged through the exhaust gas / smoke gas outlet 1035 of the low-temperature section dryer, and enters the inlet of the air heat exchanger 4 located on the first layer through the connecting pipeline, and after heat exchange in the air heat exchanger, it is discharged through the heat exchanger outlet, and enters the condenser 5 located on the first layer through the connecting pipeline for further cooling. After cooling, the gas is sent to the odor treatment system 6 located on the first layer for treatment, and the waste condensed water recovered by the condenser 5 is recovered and treated by the waste water tank 7;

[0048] The system uses the air / odor drawn into the drying room by the exhaust of the micro-negative pressure deodorization as the low-temperature drying medium. The air / odor is first sent to the air heat exchanger 4 through the connecting pipeline for heat exchange, and then enters the hot air inlet 1041 of the low-temperature dryer 1 located on the second floor through the connecting pipeline. The low-temperature drying medium air takes away the moisture in the wet sludge in the low-temperature dryer to dehydrate the wet sludge, and then discharges the wet air with a temperature of about 60-80°C from the hot air outlet 1042 of the low-temperature dryer, and is led to the deodorization system 8 located on the roof of the second floor through the connecting pipeline for treatment;

[0049] After the sludge in the system leaves the low-temperature dryer, it is pushed into the high-temperature dryer 2 through the buffer crushing bin 9 and the screw conveyor 10; the high-temperature dryer uses steam as a heat source, and the sludge is dried to the required dryness inside and then transported to the dry mud storage bin 11 for subsequent processing;

[0050] The low temperature section dryer described in the system adopts a belt type or a drum type convection dryer.

[0051] The high temperature section dryer described in the system adopts a heat conduction dryer.

[0052] The drying room 12 described in the system includes one and two floors. The high-temperature section dryer 2 is arranged on the first floor, the low-temperature section dryer 1 is arranged on the second floor, the exhaust gas condensation facilities of the high-temperature section dryer are evenly arranged on the first floor, and the deodorization system 8 is arranged on the roof of the second floor.

[0053] A low-temperature drying medium (air) collecting pipe is arranged in the drying room 12 of the system. After the gas is collected by the collecting pipe, it is firstly heated to 60-80°C by the air heat exchanger 4 arranged on the first floor, and then enters the low-temperature drying machine 1 on the second floor to dry the wet sludge.

[0054] The exhaust gas temperature of the high temperature section dryer 2 of the system varies between 95°C and 120°C, such as 100°C and 105°C.

[0055] Description of the position arrangement of this embodiment:

[0056] (1) The two-stage dryers are arranged on the first and second floors of the factory building, of which the high-temperature stage dryer is arranged on the first floor, the low-temperature stage dryer of the present invention is arranged on the second floor, and the waste gas condensation facilities of the high-temperature stage dryer are evenly arranged on the first floor. The biological deodorization facilities are arranged on the roof. Figure 3 , Figure 4 As shown,

[0057] (2) In order to prevent the leakage of slightly negative pressure gas in the dryer room, a collection pipe is set inside the room. After the gas is collected, it first passes through the air heat exchanger on the first floor and is heated to 60-80°C. Then it enters the low-temperature section dryer of the present invention on the second floor, and absorbs heat and moisture as a drying medium, and then is led to the roof deodorization system for treatment.

[0058] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low temperature section dryer, comprising a closed box, a belt-type wet material transmission mechanism, wherein the transmission mechanism comprises a transmission belt and a pulley; characterized in that: At least two layers of the transmission mechanism (102) are arranged in the box (101), and a guide inclined plate (1022) is arranged between the two layers of the transmission mechanism to receive the material coming down from the end of the conveyor belt (1021) of the upper transmission mechanism and guide it to the top of the starting end (10211) of the conveyor belt of the lower transmission mechanism; a wet material or sludge feed port (1011) is arranged at one end of the top of the box corresponding to the starting end (10211) of the conveyor belt of the upper transmission mechanism, and a wet material or sludge discharge port (1012) is arranged at the bottom of the box corresponding to the end (10212) of the conveyor belt of the lower transmission mechanism to receive the wet material discharged; A waste gas / smoke circulation channel (103) is provided below each layer of the transmission mechanism and is parallel to the transmission mechanism and along its length direction. The waste gas / smoke circulation channel is a closed cavity structure. A plurality of heat transfer pipes 1031 arranged transversely are fixed on the outer wall of the cavity structure, and both ends of the heat transfer pipes are respectively inserted into the cavity structure. The cavity structure of the upper layer is connected to one end of the cavity structure of the lower layer through a connecting pipe (1032) to form a U shape. The end face of the end of the cavity structure of the lower layer on one side of the connecting pipe is installed on the side wall of the box body for sealing; the other end of the cavity structure of the upper layer is provided with a waste gas / smoke gas outlet (1035) installed on the side wall of the box body and on the side of the wet material or sludge feed port, and the other end of the cavity structure of the lower layer is provided with a waste gas / smoke gas inlet (1034) installed on the bottom wall of the box body and on the same side as the waste gas / smoke gas outlet (1035); The space in the box body above and below the upper circulation channel in the box body forms a U-shaped hot air medium channel (104); the upper end of the U-shaped hot air medium channel is provided with a hot air outlet (1042) installed on the side wall of the box body and arranged on the same side as the exhaust gas / smoke gas outlet (1035), and the lower end thereof is provided with a hot air inlet (1041) installed on the side wall of the box body and arranged on the same side as the exhaust gas / smoke gas outlet (1035); The top surface of the box body is provided with a steam cavity which is a hollow metal sandwich structure (105); one end of the sandwich is provided with a steam / hot water medium inlet (1051) installed on the top surface of the box body, and the other end is provided with a steam / hot water medium outlet (1052) installed on the side wall of the box body and arranged on the same side as the hot air outlet (1042) on the upper part, and the steam / hot water medium is introduced into the sandwich; The connecting pipes are provided in two numbers and are located on both sides of the circulation channel and the transmission mechanism; the exhaust gas / smoke gas inlet of the lower cavity is provided in two numbers on both sides of the wet material or sludge discharge port; A condensate collection diversion port (1036) is provided on the cavity structure of the exhaust gas / smoke flow channel to connect the condensate diversion pipe outside the box to lead into the wastewater tank.

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