Sludge treatment device based on flash evaporation

Abstract

The utility model relates to a sludge treatment device based on flash evaporation, which comprises a primary flash evaporation system and any one of a hydrolysis tank and a secondary flash evaporation system. The sludge is subjected to resourceful treatment in a flash evaporation and pyrohydrolysis and / or two-stage flash evaporation mode, cell walls in the sludge can be fully and effectively broken under the low-temperature condition through the flash evaporation technology, moisture and solute in cells are released, the dehydration performance of the sludge is improved, and the dehydration efficiency of the sludge is improved. The wall-broken sludge is conveyed to the hydrolysis tank for hydrolysis and / or the second flash evaporation tank for flash evaporation and drying, and the wall-broken sludge is more easily hydrolyzed and / or dried. According to the sludge drying device, the problems of high energy consumption, large heat loss and long treatment time in the sludge drying process are solved, and the productivity is greatly improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of sludge treatment, and in particular relates to a sludge treatment device based on flash evaporation. Background Art

[0002] With the acceleration of urbanization and the development of industrialization, the sludge production of sewage treatment plants is increasing. Sludge contains a large amount of organic matter, heavy metals, pathogenic microorganisms and other harmful substances. If the sludge is not properly treated and disposed of, it will cause serious harm to the environment and human health, and will also lead to waste of resources and economic losses. Sludge hydrolysis, as a sludge treatment technology, can decompose complex organic matter in sludge into small molecular organic matter. In the hydrolysis process, it can destroy the cell structure of the sludge, release the water in the cells, reduce the water content of the sludge, and significantly improve the dewatering performance and subsequent treatment effects of the sludge. Therefore, it has received widespread attention. However, the current sludge hydrolysis and subsequent dewatering processes usually require a long reaction time and low treatment efficiency. In order to maintain a suitable reaction temperature and environment, a large amount of energy is often consumed. The operation and maintenance of the hydrolysis and subsequent dewatering equipment are relatively complex and labor-intensive. Therefore, it is of great significance to develop a process with low energy consumption and high efficiency. Summary of the Invention

[0003] The utility model aims to provide a sludge treatment device based on flash evaporation, which adopts flash evaporation technology to improve the sludge hydrolysis and drying efficiency, and can solve the technical problems of low sludge treatment efficiency and high energy consumption in the prior art.

[0004] In order to achieve the purpose of this utility model, the utility model adopts the following technical solutions:

[0005] A sludge flash thermal hydrolysis drying process comprises the following steps:

[0006] Step 1, heating the sludge;

[0007] Step 2: The heated sludge is subjected to a first-stage flash evaporation, which uses negative pressure to remove some water and rupture the microbial cells. After the flash evaporation, the steam undergoes a first pressure relief condensation process, and the uncondensed portion is returned to step 1 for further heating.

[0008] Step 3: The sludge obtained from the primary flash evaporation treatment is subjected to hydrolysis treatment or secondary flash evaporation treatment.

[0009] When step 3 uses a hydrolysis tank for hydrolysis treatment: in step 1, the heating treatment temperature is greater than 50°C and the insulation is greater than 0.1h; in step 2, the pressure in the first-stage flash evaporation system is 0.05-0.08MPa; the sludge heating temperature during hydrolysis is greater than 50°C and the insulation is greater than 0.1h.

[0010] When step 3 adopts a two-stage flash evaporation system for secondary flash evaporation treatment: in step 1, the temperature of the heating treatment is greater than 50°C; in step 2, the pressure in the first-stage flash evaporation system is 0.05-0.08MPa; and the pressure in the second-stage flash evaporation system is 0.06-0.09MPa.

[0011] After the sludge is heated, the internal pressure of the equipment for the first-stage flash evaporation is negative, so that the sludge is transported into the equipment for the first-stage flash evaporation in the form of a jet through the siphon effect formed by the pressure difference.

[0012] A flash evaporation-based sludge treatment device comprises a primary flash evaporation system and also includes either a hydrolysis tank or a secondary flash evaporation system;

[0013] The first-stage flash evaporation system is used to flash evaporation the sludge;

[0014] The hydrolysis tank is used to hydrolyze the sludge after treatment by the primary flash evaporation system;

[0015] The secondary flash evaporation system is used to flash dry the sludge treated by the primary flash evaporation system;

[0016] The primary flash evaporation system and the secondary flash evaporation system are respectively connected with negative pressure equipment for generating negative pressure in the flash evaporation system.

[0017] It also includes: a first pressure relief tank and / or a second pressure relief tank, which are respectively connected to the primary flash evaporation system and the secondary flash evaporation system, and are respectively used to perform pressure relief treatment on the steam generated by the primary flash evaporation system and the secondary flash evaporation system.

[0018] It also includes: a first sludge heating tank and / or a second sludge heating tank, which are respectively connected to the primary flash evaporation system and the secondary flash evaporation system, and are respectively used to heat the sludge entering the primary flash evaporation system and the secondary flash evaporation system.

[0019] Water inlet holes are distributed on at least part of the area of ​​the pipeline between the first sludge heating tank and the primary flash evaporation system, and / or between the second sludge heating tank and the secondary flash evaporation system, and a sleeve is provided on the outside to form a cavity between the sleeve and the pipeline, and the cavity is connected to the water inlet pipeline.

[0020] The non-condensable gas outlet of the first pressure relief tank is connected to the primary flash evaporation system, and the condensate in the second pressure relief tank is discharged through the discharge port.

[0021] A screen is provided inside the first flash evaporation system and / or the second flash evaporation system to prevent sludge from entering the pressure relief tank; a pressure gauge is also provided in the first flash evaporation system and the second flash evaporation system respectively.

[0022] The hydrolysis tank is provided with a steam relief valve.

[0023] Beneficial effects

[0024] (1) In the sludge treatment method of the present invention, flash evaporation is used to effectively improve the sludge treatment efficiency. At the same time, high temperature disinfection and rupture of microbial cells in the sludge can release water and solutes in the cells, improve the dehydration performance of the sludge, and then flash evaporation dehydration achieves harmlessness, reduction, and resource utilization of the sludge. The sludge flash drying process has a simple structure, simple operation, low energy consumption, small footprint, high degree of automation control, fast and efficient operation, and is suitable for sludge treatment in municipalities, sewage treatment plants, etc.

[0025] (2) Through the wall breaking effect, the volume of sludge can be significantly reduced, which helps to reduce the cost of subsequent treatment and disposal; during the flash evaporation process, the flash evaporation waste heat can be effectively recovered.

[0026] (3) After the wall is broken, the organic matter in the sludge is more easily degraded, reducing the amount of odor and pathogens, thereby improving the stability of the sludge.

[0027] (4) Due to the air pressure setting, the sludge can flow between different structures by controlling the air pressure difference, without the need for conveying equipment, saving overall operating energy consumption; and through the action of the negative pressure device, the continuity of the negative pressure state during the treatment process can be guaranteed.

[0028] (5) The sludge after wall breaking is easier to be hydrolyzed, thus saving energy consumption in the hydrolysis process; after hydrolysis, the sludge changes from solid to liquid.

[0029] (6) After drying, the volume and mass of the sludge are greatly reduced. The sludge becomes more stable, easier to package and transport, and can be reused as fertilizer, fuel or building material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a process flow diagram of the utility model.

[0031] Figure 2 It is a structural diagram of the present utility model.

[0032] The numbers in the figure represent: 1. discharge port; 2. heating tank body; 3. first stirring blade; 4. integrated control mechanism; 5. support mechanism; 6. stirring motor; 7. stirring shaft; 8. second stirring blade; 9. discharge port; 10. pipeline; 11. support mechanism; 12. feed port; 13. flash tank; 14. screen; 15. steam vent; 16. discharge port; 17. vacuum pump; 18. pipeline; 19. pipeline; 20. air inlet; 21. pressure relief tank; 22. discharge port; 23. support mechanism; 24. stirring motor; 25. hydrolysis tank; 26. first stirring blade; 27. stirring shaft; 28. discharge port; 29. ​​support mechanism; 30. integrated control mechanism; 31. double sleeve. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0034] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0035] like Figure 1 A sludge flash drying process is shown, wherein the flash system includes a primary flash system, a hydrolysis tank and / or a secondary flash system.

[0036] Example 1 Flash thermal hydrolysis treatment

[0037] like Figure 2 As shown. The specific operating steps are: first, add the sludge to the first sludge heating tank for preheating, set the preheating temperature to 90°C, and the speed to 150rmp. At the same time, turn on the vacuum pump connected to the flash tank, keep the first-stage flash system at room temperature, and make the pressure in the first-stage flash system reach 0.06MPa. When the sludge is heated to 90°C, open the throttle valve between the first sludge heating tank and the vacuum pump, and send the sludge in the sludge heating tank to the flash tank for flash evaporation through siphon action. Before the sludge enters the flash tank from the sludge heating tank, it is also transported through a double-tube. The inner tube of the double-tube is a sludge delivery pipe, and the outer tube is a negative pressure water pipe. There is a cavity between the inner and outer tubes. The surface of the outer tube is provided with a water inlet and a pressure valve. The flow rate of water from the outer tube into the inner tube is achieved by controlling the pressure valve. During transportation, sludge advances through the cavity between the inner and outer tubes. Pressurized water flows from the outer tube into the inner tube through the cavity, wetting the sludge surface and forming a water film on the sludge surface, reducing the adhesion between the sludge and the inner wall of the sludge tube. During the flash evaporation process, the throttle valve between the first flash evaporation system and the first pressure relief tank is opened, and the large amount of steam generated is discharged through the pipeline to the first pressure relief tank.

[0038] The sludge in the first-stage flash evaporation system is pumped into the hydrolysis tank. At the same time, the high-temperature steam in the first pressure relief tank is discharged into the hydrolysis tank as a heat source. The hydrolysis process here adopts thermal hydrolysis. The operating temperature of the hydrolysis tank is set at 120℃ and the speed is 150rpm. When the temperature rises to 120℃, it is kept at this temperature for 30 minutes. Then, the steam relief valve on the hydrolysis tank is opened to release steam, and finally the sludge is discharged.

[0039] In this embodiment, the sludge used is from a sewage treatment plant in Nanjing. Its basic parameters, sludge property parameters after flash evaporation, and property parameters after hydrolysis are shown in the following table.

[0040] Basic parameters Raw sludge Flash steaming High-temperature hydrolysis SS (%) 65.35 38.12 28.43 VSS (%) 65.82 48.31 29.53 COD (mg / L) 69840 84350 97120

[0041] Example 2: Secondary flash evaporation

[0042] The sludge in the sludge storage tank is transported to the first sludge heating tank via the sludge conveyor. The control mechanism sets the operating temperature of the first sludge heating tank to 90°C and the agitator shaft speed to 100 rpm, and the temperature begins to rise. Simultaneously, the throttle valves between the first sludge heating tank and the primary flash evaporation system, and between the primary flash evaporation system and the first pressure relief tank, are closed. The vacuum pump connected to the primary flash evaporation system is opened, reducing the pressure in the primary flash evaporation system to 0.06 MPa. The sludge temperature in the first sludge heating tank is monitored by a monitoring mechanism. When the temperature reaches 90°C, heating is immediately stopped. The throttle valve between the first sludge heating tank and the primary flash evaporation system is opened, and the sludge in the heating tank is ejected through a pipe jet into the primary flash evaporation system for flash evaporation. Immediately after opening the throttle valve between the first sludge heating tank and the primary flash evaporation system, the throttle valve between the primary flash evaporation system and the first pressure relief tank is opened, discharging the large amount of water vapor in the primary flash evaporation system into the first pressure relief tank. After the first flash evaporation process is complete, the sludge in the first flash evaporation system is pumped to the second sludge heating tank via a sludge pump. The hot steam in the first pressure relief tank is then returned to the first sludge heating tank as a heat source. The control mechanism sets the operating temperature of the second sludge heating tank to 100°C and the agitator shaft speed to 100 rpm, and the temperature is increased. Simultaneously, the throttle valves between the second sludge heating tank and the second flash evaporation system and between the second flash evaporation system and the second pressure relief tank are closed. The vacuum pump connected to the second flash evaporation system is opened, reducing the pressure in the second flash evaporation system to 0.08 MPa. The sludge temperature in the second sludge heating tank is monitored by a monitoring mechanism. When the temperature reaches 100°C, heating is immediately stopped. The throttle valve between the second sludge heating tank and the second flash evaporation system is opened, and the sludge in the second sludge heating tank is ejected through a pipe jet into the second flash evaporation system for flash evaporation. Immediately after opening the throttle valve between the second sludge heating tank and the second flash evaporation system, the throttle valve between the second flash evaporation system and the second pressure relief tank is opened, allowing the large amount of water vapor in the flash tank to be discharged into the pressure relief tank. After the secondary flash drying is complete, the sludge in the secondary flash drying system is discharged into the dry sludge tank. The high-temperature steam in the pressure relief tank is refluxed to the second sludge heating tank as a heat source, and the condensate is discharged. Water inlet holes (e.g., upstream of the pipeline) are distributed on at least a portion of the pipeline between the first sludge heating tank and the primary flash drying system, and / or between the second sludge heating tank and the secondary flash drying system. A sleeve is provided on the outside of the sleeve, forming a cavity between the sleeve and the pipeline, which is connected to the water inlet pipeline. Before the sludge enters the flash tank from the sludge heating tank, it is transported through the double sleeve. Due to the negative pressure of the flash equipment, the sludge moves to the flash system through the siphon effect. Usually, due to the poor fluidity of the sludge, if water is added to dilute it to improve the fluidity, it will lead to increased energy consumption in the subsequent drying process. However, due to the openings on the sleeve, the water in the chamber can wet the outer surface of the sludge during the negative pressure siphon process, thereby improving its fluidity in the pipeline. Moreover, since the wetting only occurs on the wall, it will not cause excessive energy consumption in the subsequent drying process.

[0043] In this embodiment, the sludge used is from a sewage treatment plant in Nanjing. Its basic parameters, sludge property parameters after primary treatment, and property parameters after secondary treatment are shown in the following table.

[0044] Basic parameters Raw sludge First-stage flash steaming Secondary flash drying SS (%) 65.35 37.66 29.39 COD / (mg / L) 69840 81460 85370

[0045] Comparative Example 1

[0046] This example compares flash hydrolysis with traditional high-temperature thermal hydrolysis. The sludge was placed in a high-pressure reactor and heated to 120°C for 2 hours. The results are shown in the table below. Traditional high-temperature thermal hydrolysis does not pre-treat the sludge's cell walls, leaving the organic matter encapsulated by the cell walls. This not only requires more energy and time to process, but also results in poor results.

[0047] Basic parameters Raw sludge High-temperature hydrolysis SS (%) 65.35 40.36 VSS (%) 65.82 42.71 COD (mg / L) 69840 78450

[0048] Comparative Example 2

[0049] This example investigates the effects of varying flash pressures on cell wall breaking. This example differs from Example 1 in that the primary flash system negative pressure is adjusted to 0.08 MPa. All other parameters remain the same, and the results are shown in the table below. The results demonstrate that a flash tank negative pressure of 0.08 MPa adversely affects cell wall breaking in sludge. However, flash pressures below 0.06 MPa require greater energy, making 0.06 MPa the optimal flash pressure for this process.

[0050] Basic parameters Raw sludge Flash steaming hydrolysis SS (%) 65.35 41.13 32.05 VSS (%) 65.82 43.11 32.79 COD (mg / L) 69840 72140 79510

[0051] Comparative Example 3

[0052] This example compares this sludge flash drying method with a conventional flash drying method without cell wall destruction. This example differs from Example 2 in that a second-stage flash drying process was used instead of a first-stage flash drying process. All other parameters remained the same, as shown in the table below. While the conventional flash drying method achieved some dehydration effect on the sludge, the sludge moisture content was only reduced by 24.87%, while the second-stage flash drying method reduced the sludge moisture content by 35.96%.

[0053] Basic parameters Raw sludge Secondary flash drying SS (%) 65.35 40.48 COD (mg / L) 69840 80600

[0054] Comparative Example 4

[0055] This example investigates the effect of varying temperatures in the second sludge heating tank on the flash evaporation wall-breaking performance. This example differs from Example 2 in that the operating temperature of the second sludge heating tank is 80°C; all other parameters remain the same. The results are shown in the table below. The results demonstrate that when the temperature in the second sludge heating tank is too low, insufficient steam is generated, resulting in low pressure within the tank. This, in turn, reduces the pressure differential between the heating tank and the negative pressure flash tank, leading to less evaporation of sludge water.

[0056] Basic parameters Raw sludge First-stage flash steaming Secondary flash drying SS (%) 65.35 42.65 38.34 COD (mg / L) 69840 74320 77650

[0057] Overall, while secondary negative pressure flash evaporation increases energy consumption, it improves sludge drying quality. Depending on your needs, you can choose either negative pressure flash thermal hydrolysis or secondary negative pressure flash evaporation to dry the sludge. Both methods significantly reduce energy consumption and improve efficiency.

Claims

1. A sludge treatment device based on flash evaporation, characterized in that: including a primary flash system and also including either a hydrolysis tank or a secondary flash system; The first-stage flash evaporation system is used to flash evaporation the sludge; The hydrolysis tank is used to hydrolyze the sludge after treatment by the primary flash evaporation system; The secondary flash evaporation system is used to flash dry the sludge treated by the primary flash evaporation system; The primary flash evaporation system and the secondary flash evaporation system are respectively connected with negative pressure equipment for generating negative pressure in the flash evaporation system.

2. The flash evaporation-based sludge treatment device according to claim 1, characterized in that: Also includes: The first pressure relief tank and / or the second pressure relief tank are respectively connected to the primary flash evaporation system and the secondary flash evaporation system, and are used to perform pressure relief treatment on the steam generated by the primary flash evaporation system and the secondary flash evaporation system respectively.

3. The sludge treatment device based on flash evaporation according to claim 1, characterized in that: It also includes: a first sludge heating tank and / or a second sludge heating tank, which are respectively connected to the primary flash evaporation system and the secondary flash evaporation system, and are respectively used to heat the sludge entering the primary flash evaporation system and the secondary flash evaporation system.

4. The flash evaporation-based sludge treatment device according to claim 3, characterized in that: Water inlet holes are distributed on at least part of the area of ​​the pipeline between the first sludge heating tank and the primary flash evaporation system, and / or between the second sludge heating tank and the secondary flash evaporation system, and a sleeve is provided on the outside to form a cavity between the sleeve and the pipeline, and the cavity is connected to the water inlet pipeline.

5. The flash evaporation-based sludge treatment device according to claim 2, characterized in that: The non-condensable gas outlet of the first pressure relief tank is connected to the primary flash evaporation system, and the condensate in the second pressure relief tank is discharged through the discharge port.

6. The flash evaporation-based sludge treatment device according to claim 2, characterized in that: A screen is provided inside the primary flash evaporation system and / or the secondary flash evaporation system to prevent sludge from entering the pressure relief tank.

7. The flash evaporation-based sludge treatment device according to claim 2, characterized in that: The first-stage flash evaporation system and the second-stage flash evaporation system are respectively provided with pressure gauges; the hydrolysis tank is provided with a steam relief valve.

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