A high-efficiency sludge drying system with cascaded energy utilization

Abstract

A high-efficiency sludge drying system with cascaded energy utilization includes at least one drying room with two floors, one on the first floor and the other on the second floor. The waste gas in the high-temperature section dryer on the first floor is dedusted by a cyclone dust collector and then enters the low-temperature section dryer on the second floor to be condensed and discharged, enters the air heat exchanger for heat exchange, enters the condenser for cooling, and is sent to the odor treatment system for treatment after cooling. The waste condensed water recovered by the condenser is recovered and treated by a wastewater tank; the air / odor in the drying room is drawn into the low-temperature section by exhaust air with micro-negative pressure deodorization as a low-temperature section drying medium, and enters the low-temperature section dryer after heat exchange by the air heat exchanger, taking away the moisture in the wet sludge, and is discharged from the low-temperature section dryer to the deodorization system on the roof of the second floor for treatment; after the sludge leaves the low-temperature section dryer, it is pushed into the high-temperature section dryer through a buffer crushing bin and a screw conveyor; after drying to the required dryness, it is transported to the dry mud storage bin. This system improves drying efficiency and reduces energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge drying treatment, and in particular relates to a high-efficiency sludge drying system with cascaded energy utilization. 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] Thermal drying is accomplished by two complementary processes: surface water vaporization and internal water diffusion. Under standard atmospheric pressure, it takes about 2600 kJ of heat energy to heat each liter of water from room temperature (20°C) to the gas phase, which is called the "basic heat energy" of the drying system.

[0004] 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. At the same time, the two-stage type of thin layer + belt dryer also has corresponding applications.

[0005] In sludge thermal drying, heat source consumption is the largest operating cost; currently, 85% of the exhaust gas from indirect drying is water vapor, which is the main energy transfer carrier for sludge drying energy consumption. However, this part of heat is currently basically taken away by cooling water and is not well utilized, resulting in energy waste.

[0006] In sludge treatment, energy consumption accounts for the main part of the treatment cost. If we can consider using low-quality heat such as waste heat from drying tail gas to do relatively easy high-water content sludge dewatering, and high-quality steam to do difficult low-water content sludge treatment, we can achieve the cascade utilization of energy. Although there will be some sacrifices in time efficiency, space, and construction investment. However, the proportion of the drying section in the entire plant area is not large, especially for projects in sewage treatment plants, the proportion is even lower, and it will not bring much impact; in terms of investment, the traditional belt drying air volume compression condensation and other circulation links can be omitted, and the impact is not too great; but the treatment cost, which is currently more critical and everyone is more concerned about, will be greatly reduced.

[0007] 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. Compared with a single-stage dryer, the energy utilization efficiency is greatly improved, but its circulating fan power consumption is higher; when the second stage sludge dryness is high, the dust content in the circulating gas is high; this process is mainly used in sludge coordinated disposal projects such as thermal power plants and cement plants, and granular sludge has a certain impact on the feed of separate incineration / pyrolysis furnaces.

[0008] At the same time, with the continuous improvement of production environment requirements, odor collection and treatment has become an indispensable key link in sludge (drying) treatment projects. Due to the large space of the room, it is difficult to completely seal it. If this part of the collected odor can be used in a coordinated manner, production efficiency will be improved.

[0009] The inventors are committed to studying how to make full use of low-grade thermal energy in the sludge drying process, realize cascade utilization of energy, save energy, reduce operating costs, promote the development of the sludge treatment industry, and provide a high-efficiency sludge drying system with cascade utilization of energy. Summary of the invention

[0010] The present invention provides a high-efficiency sludge drying system with cascaded energy utilization, which aims to solve the technical problem that the heat source consumption is not well utilized in the thermal drying of sludge, resulting in energy waste; the system medium of the present invention adopts the odor extracted from the drying room, adopts a non-gas circulation type, and sets an induced draft and deodorization device at a high position of the system, while utilizing the buoyancy of the hot gas (room odor) to save energy. The present invention will greatly reduce the drying energy consumption, thereby reducing or eliminating the amount of auxiliary fuel required by various current sludge thermal treatment methods, saving cooling water and electricity;

[0011] The present invention divides sludge dehydration into two stages, and uses the low-grade energy tail gas carried away by the exhaust gas of the second high-temperature dryer (heat conduction type) to dry the wet sludge in the first low-temperature dryer; the first low-temperature dryer is a sludge drying device that uses low-temperature waste heat, and is a belt-type or drum-type direct contact low-temperature dryer, which solves the existing low-temperature drying technology. The air is in contact with the sludge in the dryer, and 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. In the first dryer, low-quality heat is used to dehydrate and dry the wet sludge, and the water vapor in the exhaust gas is condensed at the same time, which improves the drying efficiency and reduces energy consumption.

[0012] The technical solution of the present invention is as follows:

[0013] A high-efficiency sludge drying system for cascade utilization of energy, comprising 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 comprises at least two floors, the first floor and the second floor, the exhaust gas in the high-temperature section dryer on the first floor is discharged through an exhaust gas discharge pipe, enters a cyclone dust collector on the first floor from a dust removal air inlet pipe through a connecting pipeline for dust removal, and is discharged through a dust removal exhaust pipe, the dust removal exhaust gas enters the exhaust gas / smoke flow channel of the low-temperature section dryer on the second floor through an exhaust gas / smoke gas inlet through a connecting pipeline, most of the steam in the dust removal exhaust gas is condensed in the low-temperature section dryer, and is discharged through the exhaust gas / smoke gas outlet of the low-temperature section dryer, enters the air heat exchanger inlet on the first floor through a connecting pipeline, and is discharged through the heat exchanger outlet after heat exchange in the air heat exchanger, and enters the condenser on the first floor through a connecting pipeline for further cooling, and the cooled gas is sent to the odor treatment system on the first floor for treatment, and the waste condensed water recovered by the condenser is recovered and treated through a waste water tank;

[0014] The air / odor in the drying room is drawn into the drying room by the exhaust of the micro-negative pressure deodorization as the low-temperature drying medium. It is first sent to the air heat exchanger through the connecting pipeline for heat exchange, and then enters the hot air inlet of the low-temperature drying machine 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 drying machine to dehydrate the wet sludge, and then the wet air with a temperature of about 60-80°C is discharged from the hot air outlet of the low-temperature drying machine, and is led to the deodorization system on the roof of the second floor through the connecting pipeline for treatment;

[0015] After the sludge leaves the low-temperature dryer, it is pushed into the high-temperature dryer through the buffer crushing bin and the screw conveyor; 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 for subsequent processing.

[0016] The high-efficiency sludge drying system with cascaded energy utilization, wherein the low-temperature section dryer is a belt-type or drum-type convection dryer.

[0017] The high-efficiency sludge drying system with cascaded energy utilization, wherein the high-temperature section dryer is a heat conduction dryer.

[0018] The high-efficiency sludge drying system with cascaded energy utilization is described, wherein the drying room includes one and two floors, the high-temperature section dryer is arranged on the first floor, the low-temperature section dryer 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 is arranged on the roof of the second floor.

[0019] The high-efficiency sludge drying system with energy cascade utilization is described, wherein a low-temperature drying medium (air) collection pipeline is arranged in the drying room. After the gas is collected by the collection pipeline, it is firstly heat-exchanged by the air heat exchanger 4 arranged on the first floor, and is heated to 60-80°C, and then enters the low-temperature dryer on the second floor to dry the wet sludge.

[0020] The high-efficiency sludge drying system with cascaded energy utilization, wherein the exhaust gas temperature of the high-temperature section dryer is 95°C-120°C.

[0021] The high-efficiency sludge drying system with cascaded energy utilization, wherein the 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 in addition, a wet material or sludge discharging port for receiving the wet material discharged from the bottom of the box body corresponding to the end of the transmission belt of the lower transmission mechanism is arranged at the bottom of the box body;

[0022] The low-temperature section dryer, wherein a waste gas / smoke flow channel parallel to the transmission mechanism along its length direction is provided below each layer, the waste gas / smoke flow channel is a closed cavity structure, 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, 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;

[0023] The low-temperature section dryer, wherein 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;

[0024] The low-temperature section dryer, wherein the steam chamber is arranged on the top surface of the box body and 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, and steam / hot water medium is introduced into the sandwich.

[0025] The low-temperature section dryer, wherein 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 / flue 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.

[0026] The low-temperature section dryer, wherein a condensate collection guide port 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 into the wastewater tank.

[0027] Technical features of the present invention

[0028] (1) Make full use of the steam heat in the drying tail gas;

[0029] (2) The sludge is dried in two stages, with the low-temperature stage in front and the high-temperature stage in the back. The high-temperature stage is dried by heat conduction, while the low-temperature stage is dried by heat convection. Since the sludge in the first stage is highly humid, there is no risk of dust explosion.

[0030] (3) The heat source of the low temperature section mainly utilizes the heat in the high temperature section exhaust gas, mainly the latent heat of water vapor. The exhaust gas of the high temperature section dryer enters the low temperature section dryer after cyclone dust removal, where the water vapor is condensed, and the condensate is collected and processed. The exhaust gas from the low temperature section dryer is further cooled by the air heat exchanger and water cooler and then sent to the odor treatment system.

[0031] (4) The low-temperature drying medium (air) uses the exhaust air of the micro-negative pressure deodorization in the drying room. It first passes through the air heat exchanger and then enters the low-temperature dryer. The wet air temperature out of the low-temperature dryer is about 60-80℃ and is led to the deodorization system for treatment, further reducing energy consumption.

[0032] (5) The low-temperature section dryer adopts a belt or drum-type belt heating (convection) dryer, in which the high-temperature section exhaust gas is condensed and the moisture in the wet sludge is carried away by the air (room exhaust) to achieve dehydration and drying.

[0033] Effects of the Invention

[0034] The present invention makes full use of the low-grade heat energy in the indirect drying process of sludge to achieve the cascade utilization of energy; at the same time, it makes full use of the room exhaust deodorization gas, and the air of the low-temperature section dryer does not need to be compressed and circulated continuously, reducing energy consumption. It is calculated that compared with the one-stage method, it can reduce energy consumption by 20-35%; it greatly reduces the amount of circulating cooling water used in conventional high and low temperature section dryers. Although it will increase the land area compared with the one-stage drying method, it has obvious energy-saving and water-saving effects and greatly reduces the operating cost; it improves the drying efficiency and reduces energy consumption. It can be used for new or renovated projects of sludge treatment, and has good application value and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of the low temperature section dryer of the present invention.

[0036] Figure 2 for Figure 1 The cross-sectional view of the connecting pipe 1032,

[0037] Figure 3 This is a schematic diagram of the connection and working process of the drying system of the present invention.

[0038] Figure 4 This is a schematic diagram of the plan layout of the drying system of the present invention.

[0039] Figure 5 It is a schematic diagram of the cross-sectional arrangement of the drying system of the present invention.

[0040] Description of the accompanying drawings: 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, wastewater 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;

[0041] Explanation of the numbers of the low-temperature section dryer: 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 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. DETAILED DESCRIPTION

[0042] Combine the following Figure 1-4 The present invention is described in further detail:

[0043] The present invention discloses a high-efficiency sludge drying system for energy cascade utilization, comprising a closed drying room, and a low-temperature section dryer and a high-temperature section dryer are arranged in the drying room, wherein the drying room 12 comprises at least one floor and two floors, and the exhaust gas in the high-temperature section dryer 2 located on the first floor is discharged through an exhaust gas discharge pipe, and then enters a cyclone dust collector 3 located on the first floor through a connecting pipeline from a dust removal air inlet pipe, and then is discharged through a dust removal exhaust pipe, and the dust removal exhaust gas enters a cyclone dust collector 3 located on the second floor through a connecting pipeline from an exhaust gas / smoke gas inlet 1034. The exhaust gas / smoke flow channel 103 of the low-temperature section dryer 1, after most of the steam in the dust removal tail gas is condensed in the low-temperature section dryer, is discharged through the exhaust gas / smoke gas outlet 1035 of the low-temperature section dryer, enters the inlet of the air heat exchanger 4 located on the first floor through the connecting pipeline, and after heat exchange in the air heat exchanger, is discharged through the heat exchanger outlet, enters the condenser 5 located on the first floor through the connecting pipeline for further cooling, and the cooled gas is sent to the odor treatment system 6 located on the first floor for treatment, and the waste condensed water recovered by the condenser 5 is recovered and treated by the waste water tank 7;

[0044] The air / odor in the drying room is drawn into the drying room by the exhaust of the micro-negative pressure deodorization as the low-temperature drying medium, and 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;

[0045] After the sludge 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;

[0046] The low temperature section dryer is a belt type or drum type convection dryer.

[0047] The high temperature section dryer is a heat conduction dryer.

[0048] The drying room 12 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.

[0049] A low-temperature drying medium (air) collecting pipe is arranged in the drying room 12. 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.

[0050] The exhaust gas temperature of the high temperature section dryer 2 varies between 95°C and 120°C, such as 100°C and 105°C.

[0051] The 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 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 from the wet material is arranged at the bottom of the box body corresponding to the end 10212 of the transmission belt of the lower transmission mechanism;

[0052] The low-temperature section dryer, wherein a waste gas / smoke flow channel 103 parallel to the transmission mechanism is provided below each layer 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 upper cavity structure and one end of the lower cavity structure are connected and communicated through a connecting pipe 1032 to form a U shape, and the lower cavity structure on one side of the connecting pipe is connected to the lower cavity structure. The end face of the end head is installed on the side wall of the box body for sealing; 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 body 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 body 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 cavity structure to increase the heat transfer area.

[0053] The low-temperature section dryer, wherein 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;

[0054] In the low-temperature section dryer, 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 installed on the top surface of the box body, and a steam / hot water medium outlet 1052 is provided at the other end and installed on the side wall of the box body and arranged on the same side as the hot air outlet 1042, and steam / hot water medium is introduced into the sandwich.

[0055] The low-temperature section dryer, wherein 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 / flue 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.

[0056] In the low-temperature section dryer, 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.

[0057] See also Figure 1-2 As shown, the main equipment of the system of the present invention includes: a convection type low-temperature section dryer, a buffer crushing bin, a heat conduction type high-temperature section dryer, an air heat exchanger, a condenser, an induced draft fan of the low-temperature section dryer and a deodorization system, etc.

[0058] The wet sludge first enters the low-temperature section dryer, which is a convection belt dryer. The hot gas coming out after heat exchange in the air heat exchanger, that is, the odor extracted from the room, carries away part of the moisture in the sludge. At the same time, the low-temperature section dryer is equipped with air reheating measures, and the heat source is the tail gas of the high-temperature section dryer, thereby increasing the moisture carrying capacity of the wet air. An induced draft fan is installed on the roof of the drying room at the top of the dryer to lead the hot and humid air of the low-temperature section dryer to the deodorization facility for treatment. After the sludge leaves the low-temperature section dryer, it enters the secondary heat conduction high-temperature section dryer through the buffer crushing bin;

[0059] The secondary high-temperature dryer uses steam as a heat source. After the sludge is dried to the required dryness inside, it is transported to the dry mud storage bin for subsequent treatment. The exhaust gas temperature of the dryer is about 100°C, which contains a large amount of water vapor. After passing through the dust collector, it enters the aforementioned low-temperature dryer: on the one hand, it heats the wet air in the low-temperature dryer, and on the other hand, most of the steam in the exhaust gas is condensed, collected, and guided to the wastewater tank; after leaving the dryer, the exhaust gas enters the air heat exchanger and condenser water cooling in turn to be fully cooled before entering the furnace or other odor treatment systems.

[0060] The deodorized exhaust air from the drying room enters the aforementioned low-temperature section dryer after passing through the air heat exchanger. After coming into contact with the wet sludge and absorbing moisture, it is led to the deodorization system at the top for treatment.

[0061] See also Figure 1 As shown in the figure, the wet sludge enters the beginning of the conveyor belt of the upper transmission mechanism through the top forming machine, and falls from the end of the conveyor belt through the guide inclined plate to the beginning of the conveyor belt of the lower transmission mechanism, and then is transported to the end and unloaded to the wet material or sludge discharge port at the bottom of the box. The wet sludge is transported through the upper and lower layers to extend the drying time and improve the drying efficiency.

[0062] The low-temperature section dryer described above has a closed cavity structure for the flow channel of exhaust gas / smoke under each layer of the conveyor belt, and a heat transfer heat pipe is provided in the cavity structure. The heat transfer heat pipe increases the heat transfer area, and the exhaust gas / smoke gas inlet is provided 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 to the waste water tank through the collection and diversion port of each cavity for purification and standby use; the exhaust gas (smoke) is cooled by heat exchange with the air to realize the utilization of waste heat. Since the exhaust gas / smoke flow channel is arranged below 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. After condensation, the heat released is large, which continuously heats the air medium and improves the drying efficiency.

[0063] In the low-temperature section dryer, 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.

[0064] The low-temperature section dryer described above has a channel for hot air of the drying medium above the two exhaust gas / smoke circulation channels, the hot air inlet is arranged at the bottom wet material or sludge discharge port, and the hot air outlet is arranged 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 carrying away the moisture. 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 gas / smoke circulation channel. The hot air circulates from the lower layer of the hot air medium channel to the upper outlet for discharge, which prolongs the residence time of the hot air in the box, and is continuously heated by the exhaust gas / smoke circulation channel and heat transfer heat pipe, thereby improving the moisture carrying capacity and the drying efficiency.

[0065] Example

[0066] The system of the present invention is as follows Figure 1-4 As shown, the workflow is as follows:

[0067] (1) The system of the present invention adopts a high-temperature two-stage dryer, in which the heat source of the low-temperature dryer adopts the waste heat of the high-temperature dryer. The wet sludge first enters the low-temperature dryer. The low-temperature section adopts a low-energy consumption dryer that can utilize low-temperature waste heat and uses hot air (odor) for direct drying. After the sludge is dried in the low-temperature section, it is conveyed to the high-temperature dryer on the first floor via a spiral. After reaching the predetermined dryness (generally 65-90%), it is conveyed to the dry mud storage bin for standby use.

[0068] (2) The exhaust gas generated by the high-temperature section dryer contains a large amount of steam and non-condensable gases. After being dedusted by the cyclone dust collector, it enters the aforementioned low-temperature section dryer. Most of the steam is condensed in the low-temperature section dryer, and then further cooled by the air heat exchanger and condenser before being sent to the furnace and other odor treatment facilities.

[0069] (3) After being heated in the air exchanger, the deodorized exhaust air in the drying room absorbs heat and moisture in the low-temperature section dryer, taking away part of the moisture in the sludge, thereby achieving the effect of dehydrating and drying the sludge; the hot and humid air carrying water vapor is led to the rooftop deodorization system (washing + biological deodorization) for treatment and then discharged after meeting the standards.

[0070] Description of the location and arrangement of the equipment of the system of the present invention:

[0071] (1) The two-stage dryers are arranged on the first and second floors of the drying room of the factory building, of which the high-temperature stage dryer is arranged on the first floor, the low-temperature stage dryer is arranged on the second floor, and the high-temperature stage drying waste gas condensation facilities are evenly arranged on the first floor. The biological deodorization system facilities are arranged on the roof of the floor. Figure 4 , 5 As shown:

[0072] (2) In order to prevent the leakage of slightly negative pressure gas in the drying room, a collection pipe is set up 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. It then enters the low-temperature dryer on the second floor and absorbs heat and moisture before being led to the rooftop deodorization system for treatment.

[0073] 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 high-efficiency sludge drying system with cascaded energy utilization, comprising a closed drying room, and a low-temperature section dryer and a high-temperature section dryer are arranged in the drying room, characterized in that: The drying room (12) comprises at least one floor and two floors. The exhaust gas in the high temperature section dryer (2) on the first floor is discharged through the exhaust gas discharge pipe, and then enters the cyclone dust collector (3) 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. The dust removal exhaust gas enters the exhaust gas / smoke flow channel (103) of the low temperature section dryer (1) on the second floor through the exhaust gas / smoke gas inlet (1034) through the connecting pipeline. Most of the steam is condensed in the low-temperature section dryer and 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 floor through a connecting pipeline. 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 floor through a connecting pipeline for further cooling. After cooling, the gas is sent to the odor treatment system (6) located on the first floor for treatment. The waste condensed water recovered by the condenser (5) is recovered and treated in a waste water tank 7; The air / odor in the drying room (12) is sucked into the drying room by the exhaust air of the micro-negative pressure deodorization as the low-temperature drying medium, and 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 drying machine (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 drying machine to dehydrate the wet sludge, and then discharges the wet air with a temperature of 60-80° C. from the hot air outlet (1042) of the low-temperature drying machine, and is led to the deodorization system (8) located on the roof of the second floor through the connecting pipeline for treatment; After the sludge 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; The drying room (12) comprises a first and a second floor, 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; A low-temperature drying medium (air) collecting pipeline is arranged in the drying room. After the gas is collected by the collecting pipeline, it first passes through the air heat exchanger (4) arranged on the first floor for heat exchange, is heated to 60-80° C., and then enters the low-temperature drying machine (1) on the second floor to dry the wet sludge. The 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 (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 guide 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) is arranged at the bottom of the box body corresponding to the end (10212) of the transmission belt of the lower transmission mechanism to receive the wet material discharged; A waste gas / smoke circulation channel (103) parallel to the transmission mechanism is provided below each layer 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 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), and steam / hot water medium is introduced into the sandwich.

2. The high-efficiency sludge drying system with cascaded energy utilization according to claim 1, characterized in that: The low temperature section dryer is a belt type or drum type convection dryer.

3. The high-efficiency sludge drying system with cascaded energy utilization according to claim 1, characterized in that: The high temperature section dryer is a heat conduction dryer.

4. The high-efficiency sludge drying system with cascaded energy utilization according to claim 1, characterized in that: The exhaust gas temperature of the high temperature section dryer (2) is 95°C-120°C.

5. The high-efficiency sludge drying system with cascaded energy utilization according to claim 1, characterized in that: 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.

6. The high-efficiency sludge drying system with cascaded energy utilization according to claim 1, characterized in that: 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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