Sludge hydrothermal carbonization treatment system using waste heat steam

Abstract

The application discloses a sludge hydrothermal carbonization treatment system applying waste heat steam, and belongs to the technical field of organic solid waste treatment, which comprises a hydrothermal carbonization reaction tank with a stirrer, a sludge inlet is arranged at the bottom of the hydrothermal carbonization reaction tank, a sludge outlet is arranged at the top of the hydrothermal carbonization reaction tank, the stirring shaft of the stirrer penetrates through the hydrothermal carbonization reaction tank and is communicated with a steam pipe, and a plurality of steam outlets are arranged on the hollow stirring shaft. The waste heat steam enters the sludge in the hydrothermal carbonization reaction tank through the steam outlets on the stirring shaft, the sludge is fully mixed with the steam through the stirrer, and the hydrothermal carbonization reaction of the sludge is realized. The sludge is directly heated by the waste heat steam to generate the hydrothermal carbonization reaction, the heating efficiency is improved, and the energy consumption is reduced through the direct contact and heating of the steam and the sludge; meanwhile, the steam is liquefied, the sludge fluidity is improved, the heat conduction efficiency is improved, and the hydrothermal carbonization reaction is ensured. The application has compact structure and small land occupation, and can be used for treating river dredging sludge, dewatered sludge of a sewage treatment plant or ditch sludge.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic solid waste treatment, and particularly relates to a sludge hydrothermal carbonization treatment system applying waste heat steam. BACKGROUND

[0002] The hydrothermal carbonization (HTC) technology is generated on the basis of the high-pressure chemical theory proposed by Friedrich Bergius, a German chemist who won the Nobel Prize in Chemistry in 1931. The method simulates the process of the generation of coal, petroleum and natural gas in nature, and reproduces the reaction process which takes millions of years in nature within a few hours under appropriate temperature, pressure and pH conditions. The HTC reaction is that organic materials (such as biological waste or sludge) are carbonized into HTC biochar within a few hours under the conditions of excluding air and adding catalysts, at a temperature of 180-200 DEG C and a pressure of 20-35 bar. The method is carried out in a water-containing environment, so it does not need to dry the input materials, and the method is particularly suitable for water-rich biological organic waste and sludge. After dehydration of the HTC product, the HTC biochar has a low water content, and due to its high calorific value, it can be used for climate-friendly power generation in coal-fired power plants, or as a substitute for fossil fuels in cement plants or waste incineration plants.

[0003] The sludge hydrothermal carbonization technology fully utilizes the hydrothermal reaction, and modifies and converts the sludge into biochar in a closed high-temperature and high-pressure environment, destroys extracellular polymers, and kills pathogenic bacteria and other microorganisms, thereby realizing the reduction, stabilization and harmless treatment of sludge at low cost and high efficiency. Since it is in a closed high-pressure environment, there is no water vaporization and excessive energy consumption, and compared with the thermal drying technology, the energy consumption is only 1 / 3, and the hydrothermal biochar retains the substances (organic matter and nutrients such as nitrogen and phosphorus) and energy in the sludge as much as possible.

[0004] The industrialization of the hydrothermal carbonization system can adopt intermittent production or continuous production. The intermittent production is that the materials are sent into the reaction kettle in batches, heated in a closed environment, and the materials undergo the hydrothermal carbonization reaction under a fixed temperature and pressure, cooled after the reaction time, and the reaction product is discharged, and the next batch is processed, and the cycle is repeated. The continuous production is that the materials continuously enter the reaction system, stay in the reactor for a fixed time, and then continuously discharge. The intermittent production is generally only used for research and small-scale production application due to low efficiency, and is not suitable for industrial large-scale production; and the continuous production is suitable for industrial large-scale production application.

[0005] At present, the continuous production adopts indirect heating mode, that is, fuel is used to heat heat-conducting medium, and then the heat-conducting medium is used to heat sludge to realize hydrothermal carbonization reaction. The heat is exchanged from the heat-conducting medium to the sludge, the process is complex, multi-stage heat exchange, the heat exchange efficiency is low, the energy consumption is high, and the system operation energy consumption and cost are increased. Therefore, improving the heating efficiency of sludge hydrothermal carbonization and reducing the system operation energy consumption are the main problems to be solved in the research and promotion of the technology. SUMMARY

[0006] The purpose of the present application is to provide a sludge hydrothermal carbonization treatment system applying waste heat steam, aiming at solving the technical problems of low heat exchange efficiency, high energy consumption and high operation cost in the prior art that sludge is heated by heat-conducting medium heated by fuel to realize hydrothermal carbonization reaction.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is:

[0008] A sludge hydrothermal carbonization treatment system applying waste heat steam, comprising a hydrothermal carbonization reaction tank with a stirrer, wherein the bottom of the hydrothermal carbonization reaction tank is provided with a sludge inlet, and the top of the hydrothermal carbonization reaction tank is provided with a sludge outlet for inputting and outputting sludge; the end of the stirring shaft of the stirrer penetrates through the hydrothermal carbonization reaction tank and is communicated with a steam pipe for conveying waste heat steam outside; the stirring shaft is a hollow structure, and a plurality of steam outlets are arranged on the outer wall of the stirring shaft.

[0009] Preferably, the hydrothermal carbonization reaction tank is a vertical structure, the stirrer comprises a motor, a stirring shaft and a spiral blade, the motor is arranged on the outside top of the hydrothermal carbonization reaction tank, the stirring shaft is vertically arranged at the middle position inside the hydrothermal carbonization reaction tank, the spiral blade is coiled on the outside of the stirring shaft from top to bottom and is arranged close to the inner wall of the hydrothermal carbonization reaction tank, and the spiral blade is connected with the stirring shaft in the radial direction through a plurality of connecting pipes; the lower end of the stirring shaft penetrates through the hydrothermal carbonization reaction tank and is rotatably connected with the steam pipe through a rotary joint.

[0010] Preferably, the spiral blade and the connecting pipe are both hollow structures, the two ends of the connecting pipe are communicated with the stirring shaft and the spiral blade respectively, and a plurality of steam outlets are arranged on the side walls of the spiral blade and the connecting pipe.

[0011] Preferably, a thermometer, a pH meter, a viscometer and a pressure gauge are arranged on the tank wall of the hydrothermal carbonization reaction tank, and a flow control valve, a flow meter, a pressure gauge and a thermometer are arranged on the steam pipe.

[0012] Preferably, a safety valve is further arranged on the tank wall of the hydrothermal carbonization reaction tank.

[0013] Preferably, the sludge and waste heat steam are synchronously and continuously fed into the hydrothermal carbonization reaction tank, and the ratio of the wet sludge to the waste heat steam is 100 kg of the wet sludge to 5-20 kg of the waste heat steam.

[0014] Preferably, the temperature of the waste heat steam in the steam pipe is 180-300 DEG C, and the pressure is 1-3 MPa.

[0015] Preferably, the reaction temperature in the hydrothermal carbonization reaction tank is 160-220 DEG C, the reaction time is 1-6 hours, and the working pressure is 1-2 MPa.

[0016] Preferably, the waste heat steam is from the waste heat steam of a power plant, a cement plant and / or a brick plant.

[0017] Preferably, the sludge is river dredging sludge, dewatered sludge of a sewage treatment plant and / or trench sludge, and the water content is 70-90%.

[0018] The beneficial effects generated by the above technical solution are that, compared with the prior art, the hydrothermal carbonization reaction tank is communicated with the stirring shaft through the steam pipe, the waste heat steam enters the sludge in the hydrothermal carbonization reaction tank through the steam outlet hole on the stirring shaft, the sludge and the waste heat steam are fully mixed by the stirrer, and the hydrothermal carbonization reaction of the sludge is realized. The hydrothermal carbonization reaction of the sludge is directly heated by the waste heat steam. The heating efficiency is improved, the energy consumption is reduced, the steam is liquefied, the sludge fluidity is improved, the heat conduction efficiency is improved, the ratio of the sludge to the waste heat steam is adjusted, and the hydrothermal carbonization reaction is ensured. The present application has high heating efficiency, low energy consumption, small occupied area, and can be used for treating river dredging sludge, dewatered sludge of a sewage treatment plant, trench sludge and other sludge with a water content of 70-90%. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0020] Figure 1 is a structural schematic diagram of a sludge hydrothermal carbonization treatment system using waste heat steam provided by an embodiment of the present application;

[0021] Figure 2 is Figure 1 is a connection schematic diagram of the helical blade and the stirring shaft;

[0022] In the figure: 1-hydrothermal carbonization reaction tank; 2-motor; 3-thermometer; 4-pH meter; 5-viscometer; 6-pressure gauge; 7-sludge inlet; 8-sludge outlet; 9-steam pipe; 10-helical blade; 11-stirring shaft; 12-connection pipe; 13-steam outlet hole; 14-flow control valve. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0024] Referring to Figure 1 , the present application provides a sludge hydrothermal carbonization treatment system using waste heat steam, which comprises a hydrothermal carbonization reaction tank 1 with a stirrer, wherein the bottom of the hydrothermal carbonization reaction tank 1 is provided with a sludge inlet 7 and the top is provided with a sludge outlet 8 for sludge input and output; the end of the stirring shaft 11 of the stirrer penetrates through the hydrothermal carbonization reaction tank 1 and is in communication with an external steam pipe 9 for conveying waste heat steam; the stirring shaft 11 is a hollow structure, and a plurality of steam outlets 13 are arranged on the outer wall of the stirring shaft 11.

[0025] In one specific embodiment of the present application, as shown in Figure 1 , 2 , the hydrothermal carbonization reaction tank 1 is a vertical structure, the stirrer comprises a motor 2, a stirring shaft 11 and helical blades 10, the motor 2 is arranged on the outside top of the hydrothermal carbonization reaction tank 1, the stirring shaft 11 is vertically arranged at the middle position inside the hydrothermal carbonization reaction tank 1, the helical blades 10 are arranged on the outside of the stirring shaft 11 from top to bottom and close to the inner wall of the hydrothermal carbonization reaction tank 1, and the helical blades 10 are connected to the stirring shaft 11 in a radial direction through a plurality of connecting pipes 12; the lower end of the stirring shaft 11 penetrates through the hydrothermal carbonization reaction tank 1 and is rotatably connected to the steam pipe 9 through a rotary joint. The helical blades 10 and the connecting pipes 12 are both hollow structures, the two ends of the connecting pipes 12 are respectively in communication with the stirring shaft 11 and the helical blades 10, and a plurality of steam outlets 13 are arranged on the side walls of the helical blades 10 and the connecting pipes 12, as shown in Figure 2 .

[0026] The above technical solution is further optimized, as shown in Figure 1 , the tank wall of the hydrothermal carbonization reaction tank 1 is provided with a thermometer 3, a pH meter 4, a viscometer 5 and a pressure gauge 6, and the steam pipe 9 is provided with a flow control valve 14, a flow meter, a pressure gauge 6 and a thermometer. Meanwhile, a safety valve (not shown in the figure) is also arranged on the tank wall of the hydrothermal carbonization reaction tank 1 to ensure the safe operation of the hydrothermal carbonization reaction tank 1. In specific implementation, the ratio of sludge to waste heat steam is adjusted according to the initial temperature of the sludge, the temperature and pressure of the waste heat steam and the temperature of the hydrothermal carbonization reaction tank.

[0027] In specific applications, the thermometer 3 can also be a temperature sensor, the pH meter 4 can also be a pH sensor, the viscometer 5 can also be a viscosity sensor, and the pressure gauge 6 can also be a pressure sensor. These instruments can be connected to the control console in the control room, and online measurement can be used to conveniently and timely adjust the temperature, pressure, and pH value required for the hydrothermal carbonization reaction of the sludge in the hydrothermal carbonization reaction tank 1.

[0028] The following specific examples are provided:

[0029] Treatment object: dewatered sludge from a sewage treatment plant in Maanshan, with a moisture content of 80% and an organic matter content of 50%;

[0030] Steam: waste heat steam from a power plant.

[0031] Sulfuric acid: reagent grade.

[0032] Example 1

[0033] A sludge hydrothermal carbon treatment system was designed, with a treatment capacity of 100 kg / d, a hydrothermal carbonization reaction temperature of 180°C, a reaction time of 3 h, and a reaction pressure of 1.1 MPa. The steam used had a temperature of 200°C and a pressure of 1.5 MPa.

[0034] The sludge mixing preheating tank is connected to the sludge hydrothermal carbonization reaction tank, which is connected to the sludge biochar slurry flash tank, which is connected to the sludge mixing preheating tank. There are screw pumps and control valves between the sludge mixing preheating tank and the sludge hydrothermal carbonization reaction tank, control valves between the sludge hydrothermal carbonization reaction tank and the sludge biochar slurry flash tank, and control valves and steam flow meters between the sludge biochar slurry flash tank and the sludge mixing preheating tank.

[0035] The sludge hydrothermal carbonization reaction tank has a volume of 15L and is equipped with a thermometer, a pH meter, a viscometer, and a pressure gauge. It is directly heated by steam, with a double-helix stirrer inside. The stirrer shaft and blades are hollow, connected to a steam pipeline, and communicate with the stirring shaft. Steam enters the reaction tank through the steam pipeline, enters the hollow passage of the helical blades along the hollow passage of the stirring shaft, and then passes through the steam outlets on the surface of the stirring shaft and helical blades. The steam directly contacts the sludge under stirring and heats the sludge.

[0036] The sludge is heated to 90℃ in a preheating mixing tank and then pumped into the sludge hydrothermal carbonization reactor at a rate of 4.17 kg / h. The reaction temperature in the reactor is 180℃, the pressure is 1.1 MPa, and the material remains in the reactor for 3 hours. The steam temperature is 200℃, and the pressure is 1.5 MPa. Real-time monitoring of the reactor's temperature and pressure, as well as the steam's temperature and pressure, transmits data to the control module, which then adjusts the steam flow control valve. The sludge-to-steam ratio is 4.17 kg / h sludge, and the steam flow rate is 0.65 kg / h, meaning 100 kg of sludge requires 15.58 kg of steam. The energy consumption for sludge hydrothermal carbonization is 0.35 MJ / kg.

[0037] Example 2 (Changing Steam Temperature and Pressure)

[0038] Design a sludge hydrothermal carbonization treatment system with a processing capacity of 100 kg / d. The hydrothermal carbonization reaction temperature is 180℃, the reaction time is 3 hours, and the reaction pressure is 1.1 MPa. The steam used is at a temperature of 250℃ and a pressure of 3.9 MPa.

[0039] The system is connected sequentially as follows: a sludge mixing preheating tank, a sludge hydrothermal carbonization reactor, and a sludge biochar flash tank. The sludge biochar flash tank is then connected back to the sludge mixing preheating tank. A screw pump and control valve connect the sludge mixing preheating tank and the sludge hydrothermal carbonization reactor; a control valve connects the sludge hydrothermal carbonization reactor and the sludge biochar flash tank; and a control valve and a steam flow meter connect the sludge biochar flash tank and the sludge mixing preheating tank.

[0040] The sludge hydrothermal carbonization reactor has a volume of 15L and is equipped with a thermometer, pH meter, viscometer, and pressure gauge. It uses direct steam heating and features an internal double-spiral stirrer. The stirrer shaft and blades are hollow, and an external steam pipeline connects to the stirring shaft. Steam enters the reactor through the steam pipeline, flows along the hollow passage of the stirring shaft into the hollow passage of the spiral blades, and then passes through the steam outlet holes on the surface of the stirring shaft and spiral blades. The steam directly contacts the sludge under stirring, heating the sludge.

[0041] The sludge is heated to 95℃ in a preheating mixing tank and then pumped into the sludge hydrothermal carbonization reactor at a rate of 4.17 kg / h. The reaction temperature in the reactor is 180℃, the pressure is 1.1 MPa, and the material remains in the reactor for 3 hours. The steam temperature is 250℃, and the pressure is 3.9 MPa. Real-time monitoring of the reactor's temperature and pressure, as well as the steam's temperature and pressure, transmits data to the control module, which then adjusts the steam flow control valve. The sludge-to-steam ratio is 4.17 kg / h sludge, and the steam flow rate is 0.61 kg / h, meaning 100 kg of sludge for 14.65 kg of steam. The energy consumption for sludge hydrothermal carbonization is 0.41 MJ / kg.

[0042] Example 3 (change initial temperature)

[0043] The sludge hydrothermal carbon treatment system was designed with a treatment capacity of 100 kg / d, a hydrothermal carbonization reaction temperature of 180°C, a reaction time of 3 h, and a reaction pressure of 1.1 MPa. The steam temperature used was 200°C, and the pressure was 1.5 MPa.

[0044] The sludge mixing preheating tank was connected to the sludge hydrothermal carbonization reaction tank, which was connected to the sludge biochar slurry flash tank, which was connected to the sludge mixing preheating tank. There were screw pumps and control valves between the sludge mixing preheating tank and the sludge hydrothermal carbonization reaction tank, control valves between the sludge hydrothermal carbonization reaction tank and the sludge biochar slurry flash tank, and control valves and steam flow meters between the sludge biochar slurry flash tank and the sludge mixing preheating tank.

[0045] The sludge hydrothermal carbonization reaction tank had a volume of 15 L and was equipped with a thermometer, a pH meter, a viscometer, and a pressure gauge. Direct steam heating was used, and a double helix stirrer was installed inside. The stirrer shaft and blades were hollow, and a steam pipeline was connected to them, communicating with the stirring shaft. Steam entered the reaction tank through the steam pipeline, entered the helical blade hollow passage along the stirring shaft hollow passage, and then passed through the steam outlet holes on the surface of the stirring shaft and helical blade. The steam directly contacted the sludge under stirring to heat the sludge.

[0046] The sludge was heated to 95°C in the preheating mixing tank and then pumped into the sludge hydrothermal carbonization reaction tank at a rate of 4.17 kg / h. The reaction temperature in the sludge hydrothermal carbonization reaction tank was 180°C, the pressure was 1.1 MPa, and the material stayed in the tank for 3 h. The steam temperature was 200°C, and the pressure was 1.5 MPa. By monitoring the temperature and pressure data of the reaction tank and the temperature and pressure data of the steam in real time, the transmission control module issued instructions to adjust the steam flow control valve. The ratio of sludge to steam was 4.17 kg / h of sludge and 0.61 kg / h of steam, which was equivalent to 100 kg of sludge and 14.71 kg of steam. The energy consumption of sludge hydrothermal carbonization was 0.33 MJ / kg.

[0047] Example 4 (change reaction temperature)

[0048] The sludge hydrothermal carbon treatment system was designed with a treatment capacity of 100 kg / d, a hydrothermal carbonization reaction temperature of 200°C, a reaction time of 2 h, and a reaction pressure of 1.5 MPa. The steam temperature used was 250°C, and the pressure was 3.9 MPa.

[0049] The connection sequence is: the sludge mixing preheating tank is connected to the sludge hydrothermal carbonization reaction tank, which is connected to the sludge biochar slurry flash tank, and the sludge biochar slurry flash tank is connected to the sludge mixing preheating tank. There are screw pumps and control valves between the sludge mixing preheating tank and the sludge hydrothermal carbonization reaction tank, control valves between the sludge hydrothermal carbonization reaction tank and the sludge biochar slurry flash tank, and control valves and steam flow meters between the sludge biochar slurry flash tank and the sludge mixing preheating tank.

[0050] The sludge hydrothermal carbonization reaction tank has a volume of 15L, and is equipped with a thermometer, a pH meter, a viscometer and a pressure gauge. Direct steam heating is adopted, and a double helix stirring device is arranged inside. The stirring device shaft and the blade are hollow, and are connected to a steam pipeline in communication with the stirring shaft. Steam enters the reaction tank through the steam pipeline, enters the helical blade hollow passage along the hollow passage of the stirring shaft, and then passes through the steam outlet holes on the surface of the stirring shaft and the helical blade. The steam directly contacts the sludge under stirring to heat the sludge.

[0051] The sludge is heated to 90℃ in the preheating mixing tank, and is pumped into the sludge hydrothermal carbonization reaction tank at a rate of 4.17kg / h. The reaction temperature in the sludge hydrothermal carbonization reaction tank is 200℃, and the pressure is 1.5MPa. The material stays in the sludge hydrothermal carbonization reaction tank for 3h. The steam temperature is 250℃, and the pressure is 3.9MPa. Through real-time monitoring of the temperature and pressure data of the reaction tank and the temperature and pressure data of the steam, the transmission control module sends instructions to adjust the steam flow control valve. The ratio of sludge to steam is 4.17kg / h of sludge and 0.78kg / h of steam, i.e. 100kg of sludge and 18.63kg of steam. The sludge hydrothermal carbonization energy consumption is 0.52MJ / kg.

[0052] Comparative Example

[0053] The water thermal carbonization system is divided into a front preheating system, a hydrothermal carbonization reaction system and a rear cooling system by adopting a heat conduction oil indirect heating method. The hydrothermal carbonization reaction system is heated to 200℃ by burning natural gas in a heat conduction oil furnace to heat the heat conduction oil, which indirectly exchanges heat with the hydrothermal carbonization reaction tank through the tank jacket to heat the hydrothermal carbonization reaction tank, so that the hydrothermal carbonization reaction occurs. The reaction temperature is 180℃, and the reaction time is 2h. The high-temperature material after the reaction is indirectly exchanged by heat conduction oil to cool the material to 110℃. The heat conduction oil after the heat exchange is transported to the sludge preheating system in front of the reaction tank to heat the sludge from room temperature to 60℃, and then the sludge is fed into the hydrothermal carbonization reaction tank. The sludge hydrothermal carbonization energy consumption is 0.7MJ / kg.

[0054] The parameters of the above examples and the energy consumption compared with the comparative example are shown in Table 1 below:

[0055] Table 1

[0056]

[0057] In conclusion, the sludge hydrothermal carbonization treatment system provided by the present application utilizes steam to directly heat sludge, improves heating efficiency, reduces energy consumption, simultaneously liquefies steam, improves sludge fluidity, improves heat conduction efficiency, can adjust steam flow according to initial temperature, reaction temperature, steam temperature and pressure, and further adjust the ratio of sludge and steam, to ensure that the hydrothermal carbonization reaction is carried out.

[0058] In conclusion, the present application has the following beneficial effects:

[0059] 1. The present application directly heats sludge with steam, has high heating efficiency, low energy consumption and low cost;

[0060] 2. The present application can adjust the flow according to the steam temperature and pressure in time, control the ratio of sludge and steam entering the hydrothermal carbonization reaction tank, and further control the reaction temperature;

[0061] 3. The present application directly heats sludge with steam, which can not only provide heat, but also improve material fluidity and heat exchange efficiency, and treat high solid content sludge;

[0062] 4. The present application can be continuously operated and has high treatment efficiency;

[0063] 5. The present application has small land area, low construction cost, strong controllability and is suitable for large-scale application.

[0064] In the above description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the connotation of the present application, therefore the present application is not limited by the above disclosed specific embodiments.

Claims

1. A sludge hydrochar treatment system using waste heat steam, characterized by: The water heat carbonization reaction tank with a stirrer, the bottom of the water heat carbonization reaction tank is provided with a sludge inlet, and the top of the water heat carbonization reaction tank is provided with a sludge outlet, which are used for the input of sludge and the output of sludge; The stirrer comprises a motor, a stirring shaft and a spiral blade, the motor is arranged on the outside top of the water heat carbonization reaction tank, the stirring shaft is vertically arranged in the middle position of the inside of the water heat carbonization reaction tank, the spiral blade is coiled on the outside of the stirring shaft from top to bottom, and the side of the spiral blade away from the stirring shaft is arranged close to the inner wall of the water heat carbonization reaction tank, and the spiral blade is connected with the stirring shaft in the radial direction through a plurality of connecting pipes; The end of the stirring shaft penetrates the water heat carbonization reaction tank and is connected with the steam pipe for conveying waste heat steam in the outside, the stirring shaft is a hollow structure, and a plurality of steam outlets are arranged on the outer wall of the stirring shaft; The spiral blade and the connecting pipe are both hollow structures, the two ends of the connecting pipe are connected with the stirring shaft and the spiral blade respectively, and a plurality of steam outlets are arranged on the side walls of the spiral blade and the connecting pipe; There is a gap between the stirring shaft, the connecting pipe and the spiral blade; The steam outlets on the stirring shaft are arranged in the radial direction of the stirring shaft, the steam outlets on the spiral blade comprise first steam outlets arranged in the axial direction of the stirring shaft and second steam outlets arranged obliquely to the axis of the stirring shaft.

2. The sludge hydrochar treatment system using waste heat steam according to claim 1, characterized by: The water heat carbonization reaction tank is a vertical structure, the lower end of the stirring shaft penetrates the water heat carbonization reaction tank and is connected with the steam pipe in rotation through a rotary joint.

3. The sludge hydro-char processing system using waste heat steam according to claim 1, wherein: A thermometer, a pH meter, a viscosity meter and a pressure gauge are arranged on the tank wall of the water heat carbonization reaction tank, and a flow control valve, a flow meter, a pressure gauge and a thermometer are arranged on the steam pipe.

4. The sludge hydro-char processing system using waste heat steam according to claim 3, characterized in that: A safety valve is further arranged on the tank wall of the water heat carbonization reaction tank.

5. The sludge hydro-char processing system using waste heat steam according to claim 1, wherein: Sludge and waste heat steam are synchronously and continuously input into the water heat carbonization reaction tank, and the ratio of sludge to waste heat steam input into the water heat carbonization reaction tank is: 100 kg of wet sludge and 5-20 kg of waste heat steam.

6. The sludge hydro-char processing system using waste heat steam according to claim 1, wherein: The temperature of the waste heat steam in the steam pipe is 180-300 DEG C, and the pressure is 1-3 MPa.

7. The sludge hydro-char processing system using waste heat steam according to claim 1, wherein: The reaction temperature in the water heat carbonization reaction tank is 160-220 DEG C, the reaction time is 1-6 hours, and the working pressure is 1-2 MPa.

8. The sludge hydrochar treatment system using waste heat steam according to any one of claims 1 to 7, characterized in that: The waste heat steam is from the waste heat steam of a power plant, a cement plant and / or a brick plant.

9. The sludge hydro-char processing system using waste heat steam according to claim 8, wherein: The sludge is river dredging sludge, dewatered sludge of a sewage treatment plant and / or trench sludge, and the water content is 70-90%.

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