Energy-saving sludge dewatering and drying system and method

Abstract

The invention provides an energy-saving sludge dewatering and drying system and method, belongs to the field of sludge dewatering, and is used for sludge reduction. Water vapor in the drying machine is condensed into a liquid state through the condenser and then releases heat, the sludge before dehydration is heated, the viscosity of the heated sludge is reduced, the temperature is increased, the hydrophilicity of polysaccharide and protein components in the sludge is changed, and meanwhile, due to the fact that a conditioner is added into the sludge, the sludge can be recycled. The reaction efficiency of the conditioner and the sludge is improved through heating, the dehydration performance of the sludge is improved through the factors, the dehydration efficiency in the dehydration process is improved, and more water is removed from the sludge through dehydration. Therefore, in the subsequent drying process, water needing to be further removed through drying is reduced, the energy consumption in the drying process is reduced, and the systematic energy consumption of dehydration and drying is reduced.

Description

Technical Field

[0001] The invention relates to the field of sludge dehydration, and in particular to an energy-saving sludge dehydration and drying system and method. Background Art

[0002] A large amount of sludge by-products will be generated during the treatment process of urban sewage treatment plants. According to the Urban and Rural Construction Statistical Yearbook of the Ministry of Housing and Urban-Rural Development, the sludge generated by China's urban sewage treatment plants in 2022 has reached 15.75 million tons in terms of dry matter. This type of sludge will contain a large amount of water, organic matter and pollutants, which need to be properly disposed of to avoid secondary pollution. The most common way to reduce the volume of sludge is to dewater and dry the sludge. For example, patent CN112374710A discloses a sludge dewatering and drying process technology and a dewatering and drying system, which include the following steps: 1) Sludge pretreatment: odor collection and treatment of the sludge, dehydration and conditioning of the sludge with a sludge conditioner, and disinfection and sterilization of the sludge; 2) Sludge dehydration: the conditioned sludge is subjected to high-pressure plate and frame filter pressing; 3) Sludge drying: the sludge is heated with steam, and the water vapor generated by the heating is discharged after condensation.

[0003] CN116253493A discloses a sludge dehydration and drying system and process, wherein the sludge dehydration and drying system comprises an atomization oxidation conditioning device for atomizing and oxidizing raw sludge, a high-pressure plate frame dehydration device for compressing and dehydrating the conditioned sludge, a crushing device for crushing the compressed and dehydrated sludge, and a hydrothermal drying device for hydrothermally drying the crushed sludge; wherein the water vapor generated by the hydrothermal drying device is passed to the crushing device to preheat the sludge in the crushing device.

[0004] Mechanical dehydration has low energy consumption in the process of sludge dehydration, while the energy consumption of sludge drying process is relatively high, which is about 30-300 times that of mechanical dehydration. Therefore, using mechanical dehydration and drying to reduce sludge has high energy consumption and high cost. In order to solve this problem, researchers passed the heat energy in the drying process into the heat exchanger, and utilized the heat energy in the drying process in turn. For example, patent CN105712606A discloses an integrated sludge dehydration and drying device and a sludge dehydration and drying method, including a sludge screw pump, a spiral stacked sludge dehydrator, a screw conveyor, an automatic dosing device and a drying device: the sludge screw pump, the spiral stacked sludge dehydrator, the screw conveyor and the automatic dosing device of the drying device are connected in turn through pipelines, and the automatic dosing device is connected to the spiral stacked sludge dehydrator: the drying device includes a heat pump low-temperature dryer, an induced draft fan, a first heat exchanger, a second heat exchanger, a heat pump, a water circulation pump and an electric heater, and the heat pump low-temperature dryer, the induced draft fan, the first heat exchanger, the second heat exchanger, the heat pump and the electric heater are connected in turn through ventilation ducts, and the electric heater is also connected to the heat pump low-temperature dryer through ventilation ducts. This technical solution uses a heat pump to recover the heat energy in the drying process and reuse it for drying.

[0005] In summary, the sludge reduction process usually includes mechanical dehydration and drying. Due to the high energy consumption of drying, the system performance consumption of mechanical dehydration and drying treatment is high. In order to reduce the energy consumption of the system during the dehydration and drying process, a heat recovery device is required to recover and utilize the heat energy in the drying process. Summary of the invention

[0006] In response to the above problems, the present invention provides an energy-saving sludge dehydration and drying system and method. The system combines mechanical dehydration and drying to treat the sludge, reducing the moisture content of the sludge to below 40%, and recovering the heat energy in the drying process for reuse, thereby greatly saving system energy consumption.

[0007] The present invention provides an energy-saving sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a dehydration system, a drying system and a recovery system, wherein the dehydration system includes a sludge bin, a conditioning agent bin and a dehydrator, the drying system includes a drying machine, a condenser and a heating unit, and the recovery system includes a recovery bin; The sludge bin is connected to the condenser through a pipeline, the dehydrator is connected to the dryer through a pipeline or a conveyor, the dryer is connected to the condenser through a pipeline, the dryer is connected to the heating unit through a pipeline, and the dryer is connected to the recovery bin through a pipeline or a conveyor; The condenser includes one of an indirect condenser and a direct contact condenser.

[0008] Furthermore, the system also includes a sludge heater, which is a shell and tube heat exchanger or a spiral plate heat exchanger.

[0009] Furthermore, a water inlet is arranged on the top of the sludge bin, a discharge port is arranged on the side, and a stirring device is also installed in the sludge bin.

[0010] Furthermore, the sludge in the sludge bin includes solids and water, and the water content of the sludge is greater than 90%.

[0011] Furthermore, the dehydrator is provided with a feed inlet, a discharge outlet and a separation liquid outlet.

[0012] Furthermore, the dewatering machine dewaters the sludge mechanically.

[0013] Furthermore, the dewatering machine includes one of a belt dewatering machine, a centrifugal dewatering machine, a plate and frame filter press, a wringer dewatering machine or a laminated spiral sludge dewatering machine.

[0014] Furthermore, the conditioning agent bin is arranged on the pipeline in front of the feed port of the dewatering machine, and the conditioning agent bin is provided with a discharge port. The discharge port of the conditioning agent bin is connected to the pipeline in front of the feed port of the dewatering machine through a feed pipe, and the conditioning agent in the conditioning agent bin enters the dewatering machine together with the sludge in the pipeline in front of the feed port of the dewatering machine.

[0015] Furthermore, a mixer is provided at the connection point between the discharge port of the conditioning agent bin and the pipeline in front of the feed port of the dehydrator through the feed pipe to mix the sludge with the conditioning agent in the conditioning agent bin.

[0016] Furthermore, a metering pump is installed on the feed pipe at the outlet of the conditioning agent bin.

[0017] Furthermore, the conditioning agent tank includes one or more of an inorganic conditioning agent tank and an organic conditioning agent tank.

[0018] Furthermore, when the inorganic conditioning agent bin and the organic conditioning agent bin exist at the same time, the inorganic conditioning agent in the inorganic conditioning agent bin is added first, and then the organic conditioning agent in the organic conditioning agent bin is added.

[0019] Furthermore, the inorganic conditioning bin includes an inorganic conditioning agent, the mass ratio of the inorganic conditioning agent to the solids in the sludge is (1:100)-(1:10), and the inorganic conditioning agent includes aluminum salt or iron salt.

[0020] Furthermore, the organic conditioning bin includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solids in the sludge is (1:1000)-(12:1000), and the organic conditioning agent includes polyacrylamide (PAM).

[0021] Furthermore, the sludge heater is provided with a feed port, a discharge port, a circulating water inlet and a circulating water outlet, the feed port of the sludge heater is connected to the discharge port of the sludge bin through a pipeline, and the discharge port of the sludge heater is connected to the feed port of the dehydrator through a pipeline.

[0022] Furthermore, a pump is installed on the pipeline connecting the feed port of the sludge heater and the discharge port of the sludge bin.

[0023] Furthermore, the dryer is provided with a feed inlet, a discharge port, a steam outlet, a heat medium inlet and a heat medium outlet, and the feed inlet of the dryer is connected to the discharge port of the dehydrator through a pipeline or a conveyor.

[0024] Furthermore, the dryer includes one of a thin layer dryer, a rotary disk dryer, a paddle dryer or a spiral dryer.

[0025] Furthermore, the heating unit is provided with a heat medium outlet and a heat medium inlet, the heat medium outlet of the heating unit is connected to the heat medium inlet of the dryer through a pipeline; the heat medium inlet of the heating unit is connected to the heat medium outlet of the dryer through a pipeline.

[0026] Furthermore, the heat medium in the heating unit heats the sludge in the dryer.

[0027] Furthermore, the heating unit includes one of a steam station, a steam boiler or a thermal oil heating furnace.

[0028] Furthermore, the indirect condenser is provided with a steam inlet, a water outlet, a circulating water inlet and a circulating water outlet.

[0029] Furthermore, the steam inlet of the indirect condenser is connected to the steam outlet of the dryer through a pipe, the water outlet of the indirect condenser is connected to the water inlet of the sludge bin through a pipe, the circulating water inlet of the indirect condenser is connected to the circulating water outlet of the sludge heater through a pipe, and the circulating water outlet of the indirect condenser is connected to the circulating water inlet of the sludge heater through a pipe.

[0030] Furthermore, a pump is installed on the pipe connecting the water outlet of the indirect condenser and the water inlet of the sludge bin, and on the pipe connecting the circulating water inlet of the indirect condenser and the circulating water outlet of the sludge heater.

[0031] Furthermore, the indirect condenser is one or more of a shell and tube condenser or a spiral plate condenser.

[0032] Furthermore, when the hardness of the sludge is less than 150 mg / L, the condenser is an indirect condenser or a direct contact condenser, and the direct contact condenser is provided with a steam inlet, a sludge inlet and a sludge outlet.

[0033] Furthermore, the steam inlet of the direct contact condenser is connected to the steam outlet of the dryer through a pipeline, the sludge inlet of the direct contact condenser is connected to the discharge port of the sludge bin through a pipeline, the sludge outlet of the direct contact condenser is connected to the feed port of the dehydrator through a pipeline, and the discharge port of the conditioning agent bin is connected through a feed pipe on the pipeline connecting the sludge outlet of the direct contact condenser and the feed port of the dehydrator.

[0034] Furthermore, a mixer is provided at a pipeline connecting the discharge port of the conditioning agent bin to the sludge outlet of the direct contact condenser and the feed port of the dehydrator through a feed pipe to mix the sludge with the conditioning agent in the conditioning agent bin.

[0035] Furthermore, the direct contact condenser is also provided with a spraying device, which sprays the sludge to disperse it into droplets, and the sprayed sludge is heated and mixed with the water vapor entering from the steam inlet of the direct contact condenser.

[0036] Furthermore, a pump is installed on the pipeline connecting the sludge inlet of the direct contact condenser and the discharge port of the sludge bin, and on the pipeline connecting the sludge outlet of the direct contact condenser and the feed port of the dehydrator.

[0037] Furthermore, the recovery bin is provided with a feed port, and the feed port of the recovery bin is connected to the discharge port of the drying machine through a pipeline or a conveyor.

[0038] Furthermore, the hardness of the sludge is the content of calcium carbonate in the sludge.

[0039] The present invention also provides a method for dehydrating and drying sludge using the energy-saving sludge dehydration and drying system, and the method is specifically: First, the sludge in the sludge bin is transported to the sludge heater by a pump, and then enters the dehydrator through the sludge heater for mechanical dehydration. Before entering the dehydrator, the inorganic conditioner in the inorganic conditioner bin and / or the organic conditioner in the organic conditioner bin are added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator. The dehydrated sludge enters the drying machine from the dehydrator, and no water vapor is generated in the system at this time; When the dehydrated sludge enters the dryer, the heat supply unit introduces heat medium into the dryer, and the heat medium heats and dries the dehydrated sludge in the dryer. The heated heat medium returns to the heat supply unit from the dryer for circulation. The dehydrated sludge is dried in the dryer to generate water vapor, which is condensed into liquid condensed water in the indirect condenser. The condensed water enters the sludge bin through a pump and is mixed with the undehydrated sludge. The mixed sludge is transported to the sludge heater through a pump for heating. The heated sludge enters the dehydrator for continued mechanical dehydration. The dehydrated sludge enters the dryer from the dehydrator to continue drying to generate water vapor. The water vapor continues to enter the indirect condenser to heat the circulating water and enter the sludge bin for circulation. The sludge dried in the dryer enters the recovery bin for recovery; Circulating water is passed between the circulating water inlet and outlet of the sludge heater and the circulating water inlet and outlet of the indirect condenser. The circulating water is heated by the heat energy in the water vapor condensation process in the indirect condenser and then passed into the sludge heater, where the sludge is heated and then returned to the indirect condenser through a pump for heating.

[0040] Furthermore, when the hardness of the sludge is less than 150 mg / L, the condenser is an indirect condenser or a direct contact condenser. When the condenser is a direct contact condenser, the system includes a sludge bin, an inorganic conditioning agent bin and / or an organic conditioning agent bin, a dehydrator, a dryer, a heating unit, a direct contact condenser and a recovery bin.

[0041] Furthermore, when the condenser is a direct contact condenser, the dehydration and drying method of the system comprises the following steps: First, the sludge in the sludge bin is transported to the direct contact condenser by a pump, and then sprayed by a spray device in the direct contact condenser, and then transported to the dehydrator by a pump for mechanical dehydration. Before entering the dehydrator, an inorganic conditioner in the inorganic conditioner bin and / or an organic conditioner in the organic conditioner bin is added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator. The dehydrated sludge enters the drying machine from the dehydrator, and no water vapor is generated in the system at this time; When the dehydrated sludge enters the dryer, the heat supply unit introduces heat medium into the dryer, and the heat medium heats and dries the dehydrated sludge in the dryer. The heated heat medium returns from the dryer to the heat supply unit for circulation. The dehydrated sludge is dried in the dryer to generate water vapor, which is condensed into liquid condensed water in the direct contact condenser, mixed with the sludge sprayed in the direct contact condenser and heated by the heat medium. The mixed and heated sludge is transported to the dehydrator by the direct contact condenser through a pump. In the process of conveying, inorganic conditioning agent and / or organic conditioning agent are added through the inorganic conditioning agent bin and / or the organic conditioning agent bin, the sludge is mechanically dehydrated in the dehydrator, and the removed water is discharged from the separation liquid outlet of the dehydrator, the dehydrated sludge enters the dryer from the dehydrator, the sludge is heated by the heat medium provided by the heating unit in the dryer to generate water vapor, the water vapor continues to enter the direct contact condenser to mix with the undehydrated sludge, and circulates, and the sludge dried in the dryer enters the recovery bin for recovery.

[0042] Furthermore, the hardness of the sludge is the content of calcium carbonate in the sludge.

[0043] Beneficial effects of the present invention: 1. The commonly used sludge reduction method is a combination of mechanical dehydration and drying. However, due to the low dehydration rate in the mechanical dehydration process, the energy consumption required in the drying process is high, and the heat energy of the evaporated water vapor generated in the drying process is wasted. The present invention recycles the heat energy of the evaporated water vapor in the drying process and heats the sludge first, thereby increasing the dehydration rate of the dehydrator in the system, thereby reducing the energy consumption of the drying machine. The system of the present invention is suitable for general dehydrators and drying machines sold on the market and is widely used. The present invention uses a condenser to recover heat, saving energy and reducing the system performance consumption of the dehydration and drying process. 2. The condenser in the present invention can be an indirect or direct condenser to condense the steam in the dryer. The indirect condenser can be used in all sludge reduction processes without limiting the hardness or other properties of the sludge. When the hardness of the sludge is less than 150 mg / L, an indirect condenser or a direct contact condenser can be selected to recycle the heat energy in the drying process. When the hardness is too high, the sludge in the direct contact condenser will precipitate with the condensate, thereby blocking the line. 3. In the present invention, the evaporated water vapor in the dryer is condensed into liquid through the condenser and releases heat energy to heat the sludge before dehydration. The viscosity of the heated sludge is reduced, and the increased temperature changes the hydrophilicity of the polysaccharide and protein components in the sludge. At the same time, since a conditioning agent is added to the sludge, heating improves the reaction efficiency of the conditioning agent and the sludge. These factors improve the dehydration performance of the sludge, improve the dehydration efficiency during the dehydration process, and remove more water from the sludge through dehydration. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of the energy-saving sludge dehydration and drying system described in Example 1; Figure 2 This is a schematic diagram of the structure of the energy-saving sludge dehydration and drying system described in Example 3; Figure 3 This is a schematic diagram of the structure of the energy-saving sludge dehydration and drying system described in Comparative Example 1; The numbers in the figure are 1, sludge bin; 2a, inorganic conditioning agent bin; 2b, organic conditioning agent bin; 3, sludge heater; 4, dehydrator; 5, dryer; 6, heating unit; 7, recovery bin; 8, direct contact condenser; 9, indirect condenser. DETAILED DESCRIPTION

[0045] The invention is described in detail below with reference to the embodiments: The present invention provides an energy-saving sludge dehydration and drying system and method, which recovers the evaporated steam in the dryer and then passes the recovered heat energy into the sludge to heat the sludge, thereby greatly reducing the energy consumption of the dryer.

[0046] Example 1 This embodiment provides an energy-saving sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a dehydration system, a drying system and a recovery system, wherein the dehydration system includes a sludge bin 1, a conditioning agent bin and a dehydrator 4, the drying system includes a drying machine 5, a condenser and a heating unit 6, and the recovery system includes a recovery bin 7; The sludge bin 1 is connected to the condenser through a pipeline, the dehydrator 4 is connected to the dryer 5 through a pipeline, the dryer 5 is connected to the condenser through a pipeline, the dryer 5 is connected to the heating unit 6 through a pipeline, and the dryer 5 is connected to the recovery bin 7 through a pipeline.

[0047] In this embodiment, the system further comprises a sludge heater 3; The sludge bin 1 is provided with a water inlet at the top and a discharge port at the side, and a stirring device is also installed in the sludge bin 1; The dehydrator 4 is provided with a feed inlet, a discharge outlet and a separation liquid outlet; the dehydrator 4 dehydrates the sludge mechanically; the dehydrator 4 is a centrifugal dehydrator; The conditioning agent bin is arranged on the pipeline in front of the feed port of the dewatering machine 4, and the conditioning agent bin is provided with a discharge port, and the discharge port of the conditioning agent bin is connected to the pipeline in front of the feed port of the dewatering machine 4 through a feed pipe, and the conditioning agent in the conditioning agent bin enters the dewatering machine 4 together with the sludge in the pipeline in front of the feed port of the dewatering machine 4; a mixer is arranged at the connection between the discharge port of the conditioning agent bin and the pipeline in front of the feed port of the dewatering machine 4 through the feed pipe, so as to mix the sludge with the conditioning agent in the conditioning agent bin, and a metering pump is installed on the feed pipe at the discharge port of the conditioning agent bin; The conditioning agent bin includes an organic conditioning agent bin 2b; The organic conditioning agent bin 2b includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solid in the sludge is 7:1000, and the organic conditioning agent is polyacrylamide (PAM); The sludge heater 3 is provided with a feed port, a discharge port, a circulating water inlet and a circulating water outlet. The feed port of the sludge heater 3 is connected to the discharge port of the sludge bin 1 through a pipeline, and the discharge port of the sludge heater 3 is connected to the feed port of the dehydrator 4 through a pipeline; a pump is also installed on the pipeline connecting the feed port of the sludge heater 3 and the discharge port of the sludge bin 1; the sludge heater is a shell-and-tube heat exchanger; The dryer 5 is provided with a feed inlet, a discharge outlet, a steam outlet, a heat medium inlet and a heat medium outlet. The feed inlet of the dryer 5 is connected to the discharge outlet of the dehydrator 4 through a pipeline; the dryer 5 is a thin layer dryer; The heating unit 6 is provided with a heat medium outlet and a heat medium inlet, and the heat medium outlet of the heating unit 6 is connected to the heat medium inlet of the dryer 5 through a pipeline; the heat medium inlet of the heating unit 6 is connected to the heat medium outlet of the dryer 5 through a pipeline; the heat medium in the heating unit 6 heats the sludge in the dryer 5; the heating unit 6 is a steam boiler; The condenser is an indirect condenser 9; The indirect condenser 9 is provided with a steam inlet, a water outlet, a circulating water inlet and a circulating water outlet. The steam inlet of the indirect condenser 9 is connected to the steam outlet of the dryer 5 through a pipeline, the water outlet of the indirect condenser 9 is connected to the water inlet of the sludge bin 1 through a pipeline, the circulating water inlet of the indirect condenser 9 is connected to the circulating water outlet of the sludge heater 3 through a pipeline, and the circulating water outlet of the indirect condenser 9 is connected to the circulating water inlet of the sludge heater 3 through a pipeline; A pump is also installed on the pipe connecting the water outlet of the indirect condenser 9 and the water inlet of the sludge bin 1, and on the pipe connecting the circulating water inlet of the indirect condenser 9 and the circulating water outlet of the sludge heater 3; the indirect condenser 9 is a shell and tube condenser; The recovery bin 7 is provided with a feed port, and the feed port of the recovery bin 7 is connected to the discharge port of the drying machine 5 through a pipeline.

[0048] This embodiment also provides a method for dehydrating and drying sludge using the energy-saving sludge dehydration and drying system, and the method is specifically as follows: First, the sludge in the sludge bin 1 is transported to the sludge heater 3 by a pump, and then enters the dehydrator 4 through the sludge heater 3 for mechanical dehydration. Before entering the dehydrator 4, the organic conditioning agent in the organic conditioning agent bin 2b is added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator 4. The dehydrated sludge enters the drying machine 5 from the dehydrator 4, and no water vapor is generated in the system at this time; When the dehydrated sludge enters the dryer 5, the heat supply unit 6 introduces heat medium into the dryer 5, and the heat medium heats and dries the dehydrated sludge in the dryer 5. The heated heat medium returns to the heat supply unit 6 from the dryer 5 for circulation. The dehydrated sludge is dried in the dryer 5 to generate water vapor, and the water vapor is condensed into liquid condensed water in the indirect condenser 9. The condensed water enters the sludge bin 1 through a pump and is mixed with the undehydrated sludge. The mixed sludge is transported to the sludge heater 3 through a pump for heating. The heated sludge enters the dehydrator 4 to continue mechanical dehydration. The dehydrated sludge enters the dryer 5 from the dehydrator 4 to continue drying to generate water vapor. The water vapor continues to enter the indirect condenser 9 to heat the circulating water and enter the sludge bin 1 for circulation. The sludge dried in the dryer 5 enters the recovery bin 7 for recovery. Circulating water is passed between the circulating water inlet and outlet of the sludge heater 3 and the circulating water inlet and outlet of the indirect condenser 9. The circulating water is heated by the heat energy in the water vapor condensation process in the indirect condenser 9 and then passes into the sludge heater 3. The sludge is heated in the sludge heater 3 and then returned to the indirect condenser 9 by the sludge heater 3 through a pump for heating.

[0049] In this embodiment, the initial temperature of the sludge is 15°C, the sludge hardness is 150 mg / L, the water vapor temperature in the dryer 5 is 100°C, the temperature of the liquid after condensation by the indirect condenser 9 is 85°C, the temperature of the circulating water between the circulating water outlet of the indirect condenser 9 and the circulating water inlet of the sludge heater 3 is 80°C, the temperature of the sludge transported by the sludge heater 3 to the dehydrator 4 is 65°C, the mass of the sludge in the sludge bin 1 is 100t, and the moisture content is 95%, the mass of the sludge after dehydration by the dehydrator 4 is 20t, and the moisture content is 75%, the mass of the sludge after drying by the dryer 5 is 8.3t, and the moisture content is 40%, the energy consumption of the dehydrator 4 is 16kWh, the energy consumption of the dryer 5 is 375kWh, and the system energy consumption of dehydration and drying is 391kWh.

[0050] Example 2 This embodiment provides an energy-saving sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a dehydration system, a drying system and a recovery system, wherein the dehydration system includes a sludge bin 1, a conditioning agent bin and a dehydrator 4, the drying system includes a drying machine 5, a condenser and a heating unit 6, and the recovery system includes a recovery bin 7; The sludge bin 1 is connected to the condenser through a pipeline, the dehydrator 4 is connected to the dryer 5 through a pipeline, the dryer 5 is connected to the condenser through a pipeline, the dryer 5 is connected to the heating unit 6 through a pipeline, and the dryer 5 is connected to the recovery bin 7 through a pipeline.

[0051] In this embodiment, the system further comprises a sludge heater 3; The sludge bin 1 is provided with a water inlet at the top and a discharge port at the side, and a stirring device is also installed in the sludge bin 1; The dehydrator 4 is provided with a feed inlet, a discharge outlet and a separation liquid outlet; the dehydrator 4 dehydrates the sludge mechanically; the dehydrator 4 is a centrifugal dehydrator; The conditioning agent bin is arranged on the pipeline in front of the feed port of the dewatering machine 4, and the conditioning agent bin is provided with a discharge port, and the discharge port of the conditioning agent bin is connected to the pipeline in front of the feed port of the dewatering machine 4 through a feed pipe, and the conditioning agent in the conditioning agent bin enters the dewatering machine 4 together with the sludge in the pipeline in front of the feed port of the dewatering machine 4; a mixer is arranged at the connection between the discharge port of the conditioning agent bin and the pipeline in front of the feed port of the dewatering machine 4 through the feed pipe, so as to mix the sludge with the conditioning agent in the conditioning agent bin, and a metering pump is installed on the feed pipe at the discharge port of the conditioning agent bin; The conditioning agent bin includes an organic conditioning agent bin 2b; The organic conditioning agent bin 2b includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solid in the sludge is 7:1000, and the organic conditioning agent is polyacrylamide (PAM); The sludge heater 3 is provided with a feed port, a discharge port, a circulating water inlet and a circulating water outlet. The feed port of the sludge heater 3 is connected to the discharge port of the sludge bin 1 through a pipeline, and the discharge port of the sludge heater 3 is connected to the feed port of the dehydrator 4 through a pipeline; a pump is also installed on the pipeline connecting the feed port of the sludge heater 3 and the discharge port of the sludge bin 1; the sludge heater is a shell-and-tube heat exchanger; The dryer 5 is provided with a feed inlet, a discharge outlet, a steam outlet, a heat medium inlet and a heat medium outlet. The feed inlet of the dryer 5 is connected to the discharge outlet of the dehydrator 4 through a pipeline; the dryer 5 is a thin layer dryer; The heating unit 6 is provided with a heat medium outlet and a heat medium inlet, and the heat medium outlet of the heating unit 6 is connected to the heat medium inlet of the dryer 5 through a pipeline; the heat medium inlet of the heating unit 6 is connected to the heat medium outlet of the dryer 5 through a pipeline; the heat medium in the heating unit 6 heats the sludge in the dryer 5; the heating unit 6 is a steam boiler; The condenser is an indirect condenser 9; The indirect condenser 9 is provided with a steam inlet, a water outlet, a circulating water inlet and a circulating water outlet. The steam inlet of the indirect condenser 9 is connected to the steam outlet of the dryer 5 through a pipeline, the water outlet of the indirect condenser 9 is connected to the water inlet of the sludge bin 1 through a pipeline, the circulating water inlet of the indirect condenser 9 is connected to the circulating water outlet of the sludge heater 3 through a pipeline, and the circulating water outlet of the indirect condenser 9 is connected to the circulating water inlet of the sludge heater 3 through a pipeline; A pump is also installed on the pipe connecting the water outlet of the indirect condenser 9 and the water inlet of the sludge bin 1, and on the pipe connecting the circulating water inlet of the indirect condenser 9 and the circulating water outlet of the sludge heater 3; the indirect condenser 9 is a shell and tube condenser; The recovery bin 7 is provided with a feed port, and the feed port of the recovery bin 7 is connected to the discharge port of the drying machine 5 through a pipeline.

[0052] This embodiment also provides a method for dehydrating and drying sludge using the energy-saving sludge dehydration and drying system, and the method is specifically as follows: First, the sludge in the sludge bin 1 is transported to the sludge heater 3 by a pump, and then enters the dehydrator 4 through the sludge heater 3 for mechanical dehydration. Before entering the dehydrator 4, the organic conditioning agent in the organic conditioning agent bin 2b is added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator 4. The dehydrated sludge enters the drying machine 5 from the dehydrator 4, and no water vapor is generated in the system at this time; When the dehydrated sludge enters the dryer 5, the heat supply unit 6 introduces heat medium into the dryer 5, and the heat medium heats and dries the dehydrated sludge in the dryer 5. The heated heat medium returns to the heat supply unit 6 from the dryer 5 for circulation. The dehydrated sludge is dried in the dryer 5 to generate water vapor, and the water vapor is condensed into liquid condensed water in the indirect condenser 9. The condensed water enters the sludge bin 1 through a pump and is mixed with the undehydrated sludge. The mixed sludge is transported to the sludge heater 3 through a pump for heating. The heated sludge enters the dehydrator 4 to continue mechanical dehydration. The dehydrated sludge enters the dryer 5 from the dehydrator 4 to continue drying to generate water vapor. The water vapor continues to enter the indirect condenser 9 to heat the circulating water and enter the sludge bin 1 for circulation. The sludge dried in the dryer 5 enters the recovery bin 7 for recovery. Circulating water is passed between the circulating water inlet and outlet of the sludge heater 3 and the circulating water inlet and outlet of the indirect condenser 9. The circulating water is heated by the heat energy in the water vapor condensation process in the indirect condenser 9 and then passes into the sludge heater 3. The sludge is heated in the sludge heater 3 and then returned to the indirect condenser 9 by the sludge heater 3 through a pump for heating.

[0053] In this embodiment, the initial temperature of the sludge is 15°C, the sludge hardness is 100 mg / L, the water vapor temperature in the dryer 5 is 100°C, the temperature of the liquid after condensation by the indirect condenser 9 is 85°C, the temperature of the circulating water between the circulating water outlet of the indirect condenser 9 and the circulating water inlet of the sludge heater 3 is 80°C, the temperature of the sludge transported by the sludge heater 3 to the dehydrator 4 is 65°C, the mass of the sludge in the sludge bin 1 is 100t, and the moisture content is 95%, the mass of the sludge after dehydration by the dehydrator 4 is 20t, and the moisture content is 75%, the mass of the sludge after drying by the dryer 5 is 8.3t, and the moisture content is 40%, the energy consumption of the dehydrator 4 is 16kWh, the energy consumption of the dryer 5 is 375kWh, and the system energy consumption of dehydration and drying is 391kWh.

[0054] Example 3 This embodiment provides an energy-saving sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a dehydration system, a drying system and a recovery system, wherein the dehydration system includes a sludge bin 1, a conditioning agent bin and a dehydrator 4, the drying system includes a drying machine 5, a condenser and a heating unit 6, and the recovery system includes a recovery bin 7; The sludge bin 1 is connected to the condenser through a pipeline, the dehydrator 4 is connected to the dryer 5 through a pipeline, the dryer 5 is connected to the condenser through a pipeline, the dryer 5 is connected to the heating unit 6 through a pipeline, and the dryer 5 is connected to the recovery bin 7 through a pipeline.

[0055] In this embodiment, the sludge bin 1 is provided with a water inlet at the top and a discharge port at the side, and a stirring device is also installed in the sludge bin 1; The dehydrator 4 is provided with a feed inlet, a discharge outlet and a separation liquid outlet; the dehydrator 4 dehydrates the sludge mechanically; the dehydrator 4 is a centrifugal dehydrator; The conditioning agent bin is arranged on the pipeline in front of the feed port of the dewatering machine 4, and the conditioning agent bin is provided with a discharge port, and the discharge port of the conditioning agent bin is connected to the pipeline in front of the feed port of the dewatering machine 4 through a feed pipe, and the conditioning agent in the conditioning agent bin enters the dewatering machine 4 together with the sludge in the pipeline in front of the feed port of the dewatering machine 4; a mixer is arranged at the connection between the discharge port of the conditioning agent bin and the pipeline in front of the feed port of the dewatering machine 4 through the feed pipe, so as to mix the sludge with the conditioning agent in the conditioning agent bin, and a metering pump is installed on the feed pipe at the discharge port of the conditioning agent bin; The conditioning agent bin includes an organic conditioning agent bin 2b; The organic conditioning agent bin 2b includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solid in the sludge is 7:1000, and the organic conditioning agent is polyacrylamide (PAM); The sludge heater 3 is provided with a feed port, a discharge port, a circulating water inlet and a circulating water outlet. The feed port of the sludge heater 3 is connected to the discharge port of the sludge bin 1 through a pipeline, and the discharge port of the sludge heater 3 is connected to the feed port of the dehydrator 4 through a pipeline; a pump is also installed on the pipeline connecting the feed port of the sludge heater 3 and the discharge port of the sludge bin 1; the sludge heater is a shell-and-tube heat exchanger; The dryer 5 is provided with a feed inlet, a discharge outlet, a steam outlet, a heat medium inlet and a heat medium outlet. The feed inlet of the dryer 5 is connected to the discharge outlet of the dehydrator 4 through a pipeline; the dryer 5 is a thin layer dryer; The heating unit 6 is provided with a heat medium outlet and a heat medium inlet, and the heat medium outlet of the heating unit 6 is connected to the heat medium inlet of the dryer 5 through a pipeline; the heat medium inlet of the heating unit 6 is connected to the heat medium outlet of the dryer 5 through a pipeline; the heat medium in the heating unit 6 heats the sludge in the dryer 5; the heating unit 6 is a natural gas boiler; The condenser is a direct contact condenser 8; The direct contact condenser 8 is provided with a steam inlet, a sludge inlet and a sludge outlet. The steam inlet of the direct contact condenser 8 is connected to the steam outlet of the drying machine 5 through a pipeline, the sludge inlet of the direct contact condenser 8 is connected to the discharge port of the sludge bin 1 through a pipeline, the sludge outlet of the direct contact condenser 8 is connected to the feed port of the dehydrator 4 through a pipeline, and the discharge port of the conditioning agent bin is connected to the pipeline connecting the sludge outlet of the direct contact condenser 8 and the feed port of the dehydrator 4 through a feed pipe; A mixer is provided at a pipe connecting the discharge port of the conditioning agent bin to the sludge outlet of the direct contact condenser 8 and the feed port of the dehydrator 4 through a feed pipe to mix the sludge with the conditioning agent in the conditioning agent bin; The direct contact condenser 8 is also equipped with a spraying device, which sprays the sludge to disperse it into droplets, and the sprayed sludge is heated and mixed with the water vapor entering from the steam inlet of the direct contact condenser 8; A pump is also installed on the pipe connecting the sludge inlet of the direct contact condenser 8 and the discharge port of the sludge bin 1, and on the pipe connecting the sludge outlet of the direct contact condenser 8 and the feed port of the dehydrator 4; The recovery bin 7 is provided with a feed port, and the feed port of the recovery bin 7 is connected to the discharge port of the drying machine 5 through a pipeline.

[0056] This embodiment also provides a method for dehydrating and drying sludge using the energy-saving sludge dehydration and drying system, and the method is specifically as follows: First, the sludge in the sludge bin 1 is transported to the direct contact condenser 8 by a pump, and then sprayed by the spray device in the direct contact condenser 8, and then transported to the dehydrator 4 by a pump for mechanical dehydration. Before entering the dehydrator 4, the organic conditioning agent in the organic conditioning agent bin 2b is added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator 4. The dehydrated sludge enters the drying machine 5 from the dehydrator 4, and no water vapor is generated in the system at this time; When the dehydrated sludge enters the dryer 5, the heat supply unit 6 introduces heat medium into the dryer 5, and the heat medium heats and dries the dehydrated sludge in the dryer 5. The heated heat medium returns from the dryer 5 to the heat supply unit 6 for circulation. The dehydrated sludge is dried in the dryer 5 to generate water vapor, which is condensed into liquid condensed water in the direct contact condenser 8 and mixed with the sludge sprayed in the direct contact condenser 8 and heated by the heat medium. The mixed and heated sludge is discharged from the direct contact condenser 8 through the The sludge is pumped to the dehydrator 4, and during the transportation process, an organic conditioner is added through the organic conditioner bin 2b. The sludge is mechanically dehydrated in the dehydrator 4, and the removed water is discharged from the separation liquid outlet of the dehydrator 4. The dehydrated sludge enters the dryer 5 from the dehydrator 4, and the sludge is heated by the heat medium provided by the heating unit 6 in the dryer 5 to generate water vapor. The water vapor continues to enter the direct contact condenser 8 to mix with the undehydrated sludge and circulate. The sludge dried in the dryer 5 enters the recovery bin 7 for recovery.

[0057] In this embodiment, the initial sludge temperature is 15°C, the sludge hardness is 100 mg / L, the evaporation water vapor temperature in the dryer 5 is 100°C, the temperature of the liquid condensed by the direct contact condenser 8 is 60°C, the temperature of the sludge transported to the dehydrator 4 is 60°C, the mass of the sludge in the sludge bin 1 is 100t, and the water content is 95%, the mass of the sludge after dehydration by the dehydrator 4 is 20.4t, and the water content is 75.5%, the mass of the sludge after drying by the dryer 5 is 8.3t, and the water content is 40%, the energy consumption of the dehydrator 4 is 16kWh, the energy consumption of the dryer 5 is 390kWh, and the system energy consumption of dehydration and drying is 406kWh.

[0058] Comparative Example 1 This comparative example provides a sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a sludge bin 1, an organic conditioning agent bin 2b, a dehydrator 4, a drying machine 5, a heating unit 6 and a recovery bin 7.

[0059] In this comparative example, the sludge bin 1 is provided with a water inlet at the top and a discharge port at the side, and a stirring device is also installed in the sludge bin 1; The dewatering machine 4 is provided with a feed inlet, a discharge outlet and a separation liquid outlet; the dewatering machine 4 dewaters the sludge mechanically; the dewatering machine 4 is a centrifugal dewatering machine; the dewatering machine 4 dewaters the sludge mechanically; The organic conditioning agent bin 2b is arranged on the pipeline in front of the feed port of the dehydrator 4, and the organic conditioning agent bin 2b is provided with a discharge port, and the discharge port of the organic conditioning agent bin 2b is connected to the pipeline in front of the feed port of the dehydrator 4 through a feed pipe, and the organic conditioning agent in the organic conditioning agent bin 2b enters the dehydrator 4 together with the sludge in the pipeline in front of the feed port of the dehydrator 4; a mixer is arranged at the connection between the discharge port of the organic conditioning agent bin 2b and the pipeline in front of the feed port of the dehydrator 4 through the feed pipe, so as to mix the sludge with the organic conditioning agent in the organic conditioning agent bin 2b, and a metering pump is installed on the feed pipe at the discharge port of the organic conditioning agent bin 2b; The organic conditioning agent bin 2b includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solid in the sludge is 7:1000, and the organic conditioning agent is polyacrylamide (PAM); The dryer 5 is provided with a feed inlet, a discharge port, a steam outlet, a heat medium inlet and a heat medium outlet. The feed inlet of the dryer 5 is connected to the discharge port of the dehydrator 4 through a pipeline; the dryer 5 is a thin layer dryer; the air outlet of the dryer 5 is connected to the exhaust gas treatment system; The heating unit 6 is provided with a heat medium outlet and a heat medium inlet, and the heat medium outlet of the heating unit 6 is connected to the heat medium inlet of the dryer 5 through a pipeline; the heat medium inlet of the heating unit 6 is connected to the heat medium outlet of the dryer 5 through a pipeline; the heat medium in the heating unit 6 heats the sludge in the dryer 5; the heating unit 6 is a natural gas boiler; The recovery bin 7 is provided with a feed port, and the feed port of the recovery bin 7 is connected to the discharge port of the drying machine 5 through a pipeline.

[0060] This comparative example also provides a method for dehydrating and drying sludge, which is specifically as follows: The organic conditioner in the organic conditioner bin 2b enters the feed port of the sludge bin 1 through the feed pipe from the discharge port of the organic conditioner bin 2b, and is stirred and mixed with the sludge in the sludge bin 1. The mixed sludge enters the dewatering machine 4 through the pipeline from the feed port of the dewatering machine 4 for dehydration. The dehydrated sludge enters the feed port of the dryer 5 through the pipeline from the discharge port of the dewatering machine 4. In the dryer 5, the heat medium is provided to the dryer 5 through the heating unit 6 to heat and dry the sludge in the dryer 5. The water vapor generated during the drying process is introduced into the exhaust gas treatment system. The dried sludge enters the recovery bin 7 from the discharge port of the dryer 5 through the pipeline and the feed port of the recovery bin 7 for recovery.

[0061] In this comparative example, the initial temperature of the sludge is 15°C, the evaporation water vapor temperature in the dryer 5 is 100°C, the mass of the sludge in the sludge bin 1 is 100t, and the water content is 95%. The mass of the sludge after dehydration by the dehydrator 4 is 25t, and the water content is 80%. The mass of the sludge after drying by the dryer 5 is 8.3t, and the water content is 40%. The energy consumption of the dehydrator 4 is 16kWh, the energy consumption of the dryer 5 is 565kWh, and the system energy consumption of dehydration and drying is 581kWh.

[0062] Comparative Example 2 This comparative example provides a sludge dehydration and drying system. According to the transportation direction of the sludge, the system includes a sludge bin 1, an organic conditioning agent bin 2b, a dehydrator 4, a drying machine 5 and a recovery bin 7.

[0063] In this comparative example, the sludge bin 1 is provided with a water inlet at the top and a discharge port at the side, and a stirring device is also installed in the sludge bin 1; The dewatering machine 4 is provided with a feed inlet, a discharge outlet and a separation liquid outlet; the dewatering machine 4 dewaters the sludge mechanically; the dewatering machine 4 is a centrifugal dewatering machine; the dewatering machine 4 dewaters the sludge mechanically; The organic conditioning agent bin 2b is arranged on the pipeline in front of the feed port of the dehydrator 4, and the organic conditioning agent bin 2b is provided with a discharge port, and the discharge port of the organic conditioning agent bin 2b is connected to the pipeline in front of the feed port of the dehydrator 4 through a feed pipe, and the organic conditioning agent in the organic conditioning agent bin 2b enters the dehydrator 4 together with the sludge in the pipeline in front of the feed port of the dehydrator 4; a mixer is arranged at the connection between the discharge port of the organic conditioning agent bin 2b and the pipeline in front of the feed port of the dehydrator 4 through the feed pipe, so as to mix the sludge with the organic conditioning agent in the organic conditioning agent bin 2b, and a metering pump is installed on the feed pipe at the discharge port of the organic conditioning agent bin 2b; The organic conditioning agent bin 2b includes an organic conditioning agent, the mass ratio of the organic conditioning agent to the solid in the sludge is 7:1000, and the organic conditioning agent is polyacrylamide (PAM); The dryer 5 is provided with a feed inlet, a discharge port, a steam outlet, a heat medium inlet and a heat medium outlet. The feed inlet of the dryer 5 is connected to the discharge port of the dehydrator 4 through a pipeline; the dryer 5 is a thin layer dryer; the air outlet of the dryer 5 is connected to the exhaust gas treatment system; The heating unit 6 is provided with a heat medium outlet and a heat medium inlet, and the heat medium outlet of the heating unit 6 is connected to the heat medium inlet of the dryer 5 through a pipeline; the heat medium inlet of the heating unit 6 is connected to the heat medium outlet of the dryer 5 through a pipeline; the heat medium in the heating unit 6 heats the sludge in the dryer 5; the heating unit 6 is a natural gas boiler; The recovery bin 7 is provided with a feed port, and the feed port of the recovery bin 7 is connected to the discharge port of the drying machine 5 through a pipeline.

[0064] This comparative example also provides a method for dehydrating and drying sludge, which is specifically as follows: The organic conditioner in the organic conditioner bin 2b enters the feed port of the sludge bin 1 through the feed pipe from the discharge port of the organic conditioner bin 2b, and is stirred and mixed with the sludge in the sludge bin 1. The mixed sludge enters the dewatering machine 4 through the pipeline from the feed port of the dewatering machine 4 for dehydration. The dehydrated sludge enters the feed port of the dryer 5 through the pipeline from the discharge port of the dewatering machine 4. In the dryer 5, the heat medium is provided to the dryer 5 through the heating unit 6 to heat and dry the sludge in the dryer 5. The water vapor generated during the drying process is introduced into the exhaust gas treatment system. The dried sludge enters the recovery bin 7 from the discharge port of the dryer 5 through the pipeline and the feed port of the recovery bin 7 for recovery.

[0065] In this comparative example, the water vapor temperature in the dryer 5 is 100°C, the mass of the sludge in the sludge bin 1 is 100t, and the water content is 95%. The mass of the sludge after dehydration by the dehydrator 4 is 27.8t, and the water content is 82%. The mass of the sludge after drying by the dryer 5 is 8.3t, and the water content is 40%. The energy consumption of the dehydrator 4 is 5kWh, the energy consumption of the dryer 5 is 660kWh, and the system energy consumption of dehydration and drying is 665kWh.

[0066] Table 1

[0067] As shown in Table 1, the sludge is dehydrated and dried by the systems in Examples 1-3 of the present invention, and the heat energy in the drying process is recovered and reused to heat the sludge, so that the energy consumption of the drying process is greatly reduced.

[0068] Based on the above, it can be seen that the energy-saving sludge dehydration and drying system and method of the present invention have a wide range of applications, low cost, and high market prospects.

[0069] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. An energy-saving sludge dehydration and drying system, characterized in that: According to the transportation direction of the sludge, the system comprises a dehydration system, a drying system and a recovery system, wherein the dehydration system comprises a sludge bin (1), a conditioning agent bin and a dehydrator (4), the drying system comprises a drying machine (5), a condenser and a heating unit (6), and the recovery system comprises a recovery bin (7); The sludge bin (1) is connected to the condenser via a pipeline, the dehydrator (4) is connected to the dryer (5) via a pipeline or a conveyor, the dryer (5) is connected to the condenser via a pipeline, the dryer (5) is connected to the heating unit (6) via a pipeline, and the dryer (5) is connected to the recovery bin (7) via a pipeline or a conveyor; The condenser comprises an indirect condenser (9) or a direct contact condenser (8).

2. The energy-saving sludge dehydration and drying system according to claim 1 is characterized in that: The system further comprises a sludge heater (3), wherein the sludge heater (3) is a shell-and-tube heat exchanger or a spiral plate heat exchanger.

3. The energy-saving sludge dehydration and drying system according to claim 1 is characterized in that: The sludge bin (1) is provided with a water inlet at the top and a material outlet at the side. The sludge bin (1) is also provided with a stirring device.

4. The energy-saving sludge dehydration and drying system according to claim 1 is characterized in that: The conditioning agent bin is arranged on the pipeline in front of the feed port of the dewatering machine (4), and the conditioning agent bin is provided with a discharge port. The discharge port of the conditioning agent bin is connected to the pipeline in front of the feed port of the dewatering machine (4) through a feed pipe, and the conditioning agent in the conditioning agent bin enters the dewatering machine (4) together with the sludge in the pipeline in front of the feed port of the dewatering machine (4).

5. The energy-saving sludge dehydration and drying system according to claim 4 is characterized in that: A mixer is provided at the connection point between the discharge port of the conditioning agent bin and the pipeline in front of the feed port of the dewatering machine (4) through the feed pipe to mix the sludge with the conditioning agent in the conditioning agent bin.

6. The energy-saving sludge dehydration and drying system according to claim 2 is characterized in that: The sludge heater (3) is provided with a feed inlet, a discharge outlet, a circulating water inlet and a circulating water outlet; the feed inlet of the sludge heater (3) is connected to the discharge outlet of the sludge bin (1) via a pipeline; and the discharge outlet of the sludge heater (3) is connected to the feed inlet of the dehydrator (4) via a pipeline.

7. The energy-saving sludge dehydration and drying system according to claim 1 is characterized in that: The indirect condenser (9) is provided with a steam inlet, a water outlet, a circulating water inlet and a circulating water outlet.

8. The energy-saving sludge dehydration and drying system according to claim 2 is characterized in that: The steam inlet of the indirect condenser (9) is connected to the steam outlet of the dryer (5) through a pipeline, the water outlet of the indirect condenser (9) is connected to the water inlet of the sludge bin (1) through a pipeline, the circulating water inlet of the indirect condenser (9) is connected to the circulating water outlet of the sludge heater (3) through a pipeline, and the circulating water outlet of the indirect condenser (9) is connected to the circulating water inlet of the sludge heater (3) through a pipeline.

9. The energy-saving sludge dehydration and drying system according to claim 8 is characterized in that: A pump is also installed on the pipe connecting the water outlet of the indirect condenser (9) and the water inlet of the sludge bin (1), and on the pipe connecting the circulating water inlet of the indirect condenser (9) and the circulating water outlet of the sludge heater (3).

10. A method for dehydrating and drying sludge using the energy-saving sludge dehydration and drying system according to any one of claims 1 to 9, characterized in that: The method is specifically as follows: First, the sludge in the sludge bin (1) is transported to the sludge heater (3) by a pump, and then enters the dehydrator (4) through the sludge heater (3) for mechanical dehydration. Before entering the dehydrator (4), an inorganic conditioning agent in the inorganic conditioning agent bin (2a) and / or an organic conditioning agent in the organic conditioning agent bin (2b) is added to the transported sludge, and the removed water is discharged from the separation liquid outlet of the dehydrator (4). The dehydrated sludge enters the drying machine (5) from the dehydrator (4), and no water vapor is generated in the system at this time. When the dehydrated sludge enters the dryer (5), the heating unit (6) introduces heat medium into the dryer (5), and the heat medium heats and dries the dehydrated sludge in the dryer (5). The heated heat medium returns from the dryer (5) to the heating unit (6) for circulation. The dehydrated sludge is dried in the dryer (5) to generate water vapor, which is condensed into liquid condensed water in the indirect condenser (9). The condensed water enters the sludge bin (1) through a pump and condenses with the un The dehydrated sludge is mixed, and the mixed sludge is transported to the sludge heater (3) through a pump for heating. The heated sludge enters the dehydrator (4) for further mechanical dehydration. The dehydrated sludge enters the dryer (5) from the dehydrator (4) for further drying to generate water vapor. The water vapor continues to enter the indirect condenser (9) to heat the circulating water, and enters the sludge bin (1) for circulation. The sludge dried in the dryer (5) enters the recovery bin (7) for recovery. Circulating water is passed between the circulating water inlet and outlet of the sludge heater (3) and the circulating water inlet and outlet of the indirect condenser (9). The circulating water is heated by the heat energy in the process of water vapor condensation in the indirect condenser (9) and then passed into the sludge heater (3). The sludge is heated in the sludge heater (3) and then returned to the indirect condenser (9) by the sludge heater (3) through a pump for heating.

Images