Three-cycle high-salinity wastewater low-temperature scraper drying system

Abstract

The utility model relates to a triple-cycle high-salinity wastewater low-temperature scraper drying system which comprises a roller scraper dryer, a steam condensation chamber, a condensed water tank and a vacuum pump, the vacuum pump vacuumizes the drying cavity through the condensate water tank and the steam condensation chamber. The first heat exchange cycle is suitable for exchanging heat absorbed by the steam condensation chamber to the third heat exchange cycle; the second heat exchange cycle is suitable for exchanging heat of the third heat exchange cycle to the water jacket; and the heat exchange ends on the two sides of the third heat exchange cycle are connected with the first heat exchange cycle and the second heat exchange cycle correspondingly. The three heat exchange cycles work cooperatively, the heat of the first heat exchange cycle is reduced, the heat provided for the second heat exchange cycle by the third heat exchange cycle is reduced, and the hot water in the second heat exchange cycle can still heat the materials in the drying cavity by exceeding the boiling point rise through the auxiliary heat, so that the low water content of the dry materials is effectively ensured.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection, specifically to a three-cycle high-salt wastewater low-temperature scraper drying system. Background Technology

[0002] In recent years, due to the rigid demand for wastewater treatment and water reuse, membrane treatment technologies, including reverse osmosis and nanofiltration, have been widely used. The clear liquid from the membrane is reused as clean water resources, while the concentrated liquid from the membrane contains high salt content and substances such as COD and total nitrogen that have not been completely removed. After further concentration by evaporation or other methods, it cannot be solidified by traditional crystallization. Therefore, drying technology has become a good choice.

[0003] Current drying technologies for high-salinity wastewater include evaporative drying, spray drying, and drum drying. Evaporative drying, further divided into flue gas evaporative drying and bypass flue gas evaporative drying, is primarily used in thermal power plants, utilizing the heat from high-temperature flue gas for drying, and has specific application requirements. Spray drying technology requires atomizing the high-salinity wastewater and then exposing it to filtered and preheated air, causing rapid evaporation of moisture to obtain a dry solid. This technology has high requirements for the surface tension, viscosity, and other impurities in the high-salinity wastewater; otherwise, the wastewater cannot form an atomized state, affecting the drying effect. Rotary drum drying is divided into outer drum drying and inner drum drying. The heat source for outer drum drying is inside the drum, while the heat source for inner drum drying is in the outer jacket of the drum's outer wall. When the high-salt wastewater comes into contact with the rotating outer wall of the outer drum, the water evaporates. Inside the inner drum, the high-salt wastewater is rapidly evaporated through convective and radiative heat transfer generated by the heat source in the outer jacket. With the development of technology, the focus is gradually shifting to inner drum scraper drying, which has lower requirements for the water quality of high-salt wastewater than spray drying and higher thermal efficiency than outer drum scraper drying.

[0004] To further reduce energy consumption and adapt the device to applications without steam or thermal oil heat sources, low-temperature heat pump drum scraper drying technology is gradually emerging. Patent number CN211215519U describes a heat pump type low-temperature crystallizer that combines heat pump and drying. It uses a heat medium to cool secondary steam in a steam condensing chamber while simultaneously gaining heat. After being further processed by a refrigeration compressor and transformed into a high-temperature, high-pressure gas, the gas returns to the jacket of the drum scraper, releasing heat to the wastewater to be evaporated and crystallized within the drum scraper. This causes the water in the wastewater to evaporate, forming secondary steam that enters the steam condensing chamber. The heat medium, after releasing its heat, becomes a liquid, which, after passing through a throttling valve, becomes a low-temperature, low-pressure liquid before returning to the steam condensing chamber to absorb heat from the secondary steam. In this patent, the hot and cold cycle of the thermal medium achieves the evaporation and drying of wastewater and the condensation of secondary steam. However, it also has two major drawbacks: First, the jacket of the drum scraper is filled with a high-temperature and high-pressure thermal medium, which is quite sensitive and requires a high pressure resistance rating for the drum scraper equipment itself, resulting in high equipment manufacturing costs. Second, as the material evaporation progresses, water molecules with high mobility on the material surface and water molecules with high diffusion capacity in the middle layer evaporate. However, the water molecules in the innermost layer of the material have a lower evaporation rate, so the amount of secondary steam formed in the drum scraper dryer gradually decreases. Consequently, the heat obtained by the thermal medium from the secondary steam in the condenser decreases, and the heat provided to the outer jacket of the drum scraper dryer becomes less. Ultimately, this results in the dried material still containing a high moisture content and failing to dry completely. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a three-circulation high-salt wastewater low-temperature scraper drying system to solve the technical problems of high manufacturing cost and low drying quality of previous drum scraper equipment.

[0006] The technical solution adopted by this utility model to solve its technical problem is:

[0007] First aspect:

[0008] A three-cycle low-temperature scraper dryer system for high-salt wastewater is provided, including:

[0009] The dryer includes a drum scraper dryer, a steam condensing chamber, a condensate tank, and a vacuum pump. The steam condensing chamber is connected to the drying chamber of the drum scraper dryer. The condensate tank is connected to the condensate outlet of the steam condensing chamber. The outlet of the condensate tank is connected to a water pump. The vacuum pump is connected to the condensate tank and evacuates the drying chamber through the condensate tank and the steam condensing chamber.

[0010] The first heat exchange cycle has one heat exchange end connected to the steam condensing chamber and the other heat exchange end connected to the third heat exchange cycle. The first heat exchange cycle is adapted to exchange the heat absorbed by the steam condensing chamber to the third heat exchange cycle.

[0011] The second heat exchange cycle has one heat exchange end connected to the water jacket of the drum scraper dryer and the other heat exchange end connected to the third heat exchange cycle. The second heat exchange cycle is adapted to exchange the heat of the third heat exchange cycle to the water jacket.

[0012] The third heat exchange cycle has its two heat exchange ends connected to the first and second heat exchange cycles, respectively.

[0013] Furthermore, the first heat exchange cycle includes a condenser, a first heat exchanger, a first circulation pipeline, and a circulation pump;

[0014] The condenser is installed in the steam condensation chamber, and the condenser and the shell cavity of the first heat exchanger form a first circulation pipeline, and the circulation pump is installed on the first circulation pipeline.

[0015] Furthermore, the second heat exchange cycle includes a second heat exchanger and a second circulation pipeline;

[0016] The second circulation pipeline connects the water jacket and the shell cavity of the second heat exchanger.

[0017] Furthermore, an electric auxiliary heater is installed on the second circulation pipeline.

[0018] Furthermore, the third heat exchange cycle includes a first heat exchanger, a second heat exchanger, a compressor, a third circulation pipeline, and a throttling valve;

[0019] The compressor and the throttle valve are installed on the second circulation pipeline, which is connected to the cavity of the first heat exchanger and the cavity of the second heat exchanger, respectively.

[0020] The second aspect:

[0021] A method for operating the above-mentioned three-cycle high-salt wastewater low-temperature scraper drying system is provided, the method being as follows:

[0022] The second heat exchange cycle is started, and the water jacket is heated by electric auxiliary heating. When the heating temperature rises to 55-65°C, the material is fed into the drying chamber.

[0023] Start the vacuum pump and control the vacuum level to 82-88%. The vacuum pump draws the steam in the drying chamber into the steam condensing chamber for condensation, and the condensate is drawn into the condensate tank.

[0024] Start the first heat exchange cycle, adjust the flow rate of the heat exchange medium in the circulating pump so that the temperature range of the medium entering the condenser is 30-40℃ and the temperature range of the medium exiting the condenser is controlled at 40-50℃; the temperature range of the medium entering the first heat exchanger is controlled at 40-50℃ and the temperature range of the medium exiting the first heat exchanger is controlled at 30-40℃.

[0025] Start the third heat exchange cycle, start the compressor and throttle valve, and control the temperature range of the heat exchange medium entering the first heat exchanger to be 25-30℃, and the temperature range of the heat exchange medium exiting the first heat exchanger to be 35-45℃; after the compressor does work, the temperature is controlled to be 90-100℃.

[0026] When the electric auxiliary heating is stopped, the temperature range of the hot water entering the second heat exchanger in the second heat exchange cycle is controlled at 55-65℃. After heat exchange with the second heat exchanger, the temperature range of the hot water exiting the second heat exchanger is controlled at 75-85℃.

[0027] By interlocking the water level of the outlet pump and the condensate tank, the water level of the condensate tank is controlled within the range of 30% to 80%.

[0028] The rotation speed of the scraper in the drum scraper dryer is controlled at 4 to 10 rpm. After the dry material is discharged, the moisture content is tested and controlled to be within 10% by adjusting the rotation speed.

[0029] When all feeding is finished, the boiling point of the material in the drum scraper dryer rises and the secondary steam gradually decreases, then start the electric auxiliary heating again to keep the temperature of the hot water entering the water jacket in the second heat exchange cycle not lower than 80℃.

[0030] Finally, stop the compressor, close the expansion valve, and stop the third heat exchange cycle;

[0031] Stop the circulating pump and stop the first heat exchange cycle;

[0032] Stop the electric auxiliary heating and stop the second heat exchange cycle;

[0033] Once all the dry material in the drum scraper dryer has been discharged, the vacuum pump is stopped.

[0034] The beneficial effects of this utility model are:

[0035] This utility model's three-cycle high-salt wastewater low-temperature scraper drying system does not require traditional heat sources such as steam or heat transfer oil; it can operate simply by being powered on.

[0036] By avoiding the direct filling of expensive and highly sensitive thermal media into the jacket of the drum scraper dryer, the pressure resistance level and manufacturing difficulty of the drum scraper dryer body are reduced.

[0037] During startup, this system employs electric auxiliary heating to heat the low-temperature hot water within the jacket, thus avoiding the problem of insufficient heat supplied to the working medium by the heater due to insufficient secondary steam during startup. During shutdown, the electric auxiliary heating automatically activates, ensuring that the boiling point of complex materials increases after concentration, even as the amount of secondary steam gradually decreases.

[0038] The three heat exchange cycles work together. The heat supplied to the first heat exchange cycle is reduced, and the heat supplied to the second heat exchange cycle by the third heat exchange cycle is also reduced. However, the hot water in the second heat exchange cycle can still heat the material in the drying chamber above the boiling point through auxiliary heating, thereby effectively ensuring a low moisture content of the dried material. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic diagram of the three-cycle high-salt wastewater low-temperature scraper drying system of this utility model;

[0041] Among them, 1. Drum scraper dryer, 11. Water jacket, 2. Steam condensation chamber, 3. Condensate tank, 31. Water pump, 4. Vacuum pump;

[0042] 51. First heat exchanger; 52. Second heat exchanger;

[0043] 61. Condenser; 62. Circulating pump;

[0044] 71. Electric auxiliary heating;

[0045] 81. Compressor; 82. Throttling valve. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0047] This application provides a three-cycle high-salinity wastewater low-temperature scraper drying system, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0048] To address the technical problems of high manufacturing cost and low drying quality in existing drum scraper drying equipment, one embodiment of this application provides a three-cycle low-temperature scraper drying system for high-salt wastewater. This is described in detail below.

[0049] like Figure 1 As shown, a three-cycle high-salt wastewater low-temperature scraper drying system includes...

[0050] The dryer comprises a drum scraper dryer 1, a steam condensing chamber 2, a condensate tank 3, and a vacuum pump 4; the steam condensing chamber 2 is connected to the drying chamber of the drum scraper dryer 1, the condensate tank 3 is connected to the condensate outlet of the steam condensing chamber 2, the outlet of the condensate tank 3 is connected to a water pump 31, and the vacuum pump 4 is connected to the condensate tank 3, and the vacuum pump 4 evacuates the drying chamber through the condensate tank 3 and the steam condensing chamber 2;

[0051] The first heat exchange cycle has one heat exchange end connected to the steam condensing chamber 2 and the other heat exchange end connected to the third heat exchange cycle. The first heat exchange cycle is adapted to exchange the heat absorbed by the steam condensing chamber 2 to the third heat exchange cycle.

[0052] The second heat exchange cycle has one heat exchange end connected to the water jacket 11 of the drum scraper dryer 1, and the other heat exchange end connected to the third heat exchange cycle. The second heat exchange cycle is adapted to exchange the heat of the third heat exchange cycle to the water jacket 11.

[0053] The third heat exchange cycle has its two heat exchange ends connected to the first and second heat exchange cycles, respectively.

[0054] Specifically, as an optional implementation method in this embodiment, such as Figure 1 As shown, the first heat exchange cycle includes a condenser 61, a first heat exchanger 51, a first circulation pipeline, and a circulation pump 62.

[0055] The condenser 61 is installed in the steam condensation chamber 2. The condenser 61 and the shell cavity of the first heat exchanger 51 form a first circulation pipeline. The circulation pump 62 is installed on the first circulation pipeline.

[0056] In this embodiment, the heat exchange medium in the first circulation pipeline is a mixed refrigerant of R410A, R452B, and R454B.

[0057] During operation, the steam generated by the wastewater in the drum scraper dryer enters the steam condensing chamber 2. After encountering the condenser 61, it liquefies into condensate. While condensing the secondary steam, the condenser 61 absorbs the heat of the secondary steam and becomes high-temperature water, which is then transferred to the first heat exchanger 51. In the first heat exchanger 51, the heat exchange medium is released and the water is cooled, becoming low-temperature water. The low-temperature water flows back to the condenser 61 under the action of the circulating pump 62.

[0058] After being cooled in the steam condenser 2, the secondary steam becomes condensate and flows from the bottom of the steam condenser 2 to the condensate tank, and is then transported to the reuse point by the outlet pump 31.

[0059] The vacuum degree inside the drum scraper dryer 1 is adjusted by vacuum pump 4, which connects the vacuum degree in the condensate tank with the vacuum degree in the steam condensation chamber 2 and the drying chamber, and adjusts the vacuum degree to about 85%, so that the evaporation temperature of the wastewater in the drum scraper dryer 1 is controlled at about 60℃.

[0060] Specifically, as an optional implementation method in this embodiment, such as Figure 1 As shown, the second heat exchange cycle includes a second heat exchanger 52 and a second circulation pipeline;

[0061] The second circulation pipeline connects the water jacket 11 and the shell cavity of the second heat exchanger 52.

[0062] The heat exchange medium in the second circulation pipeline is water.

[0063] The hot water in the water jacket 11 heats the material inside the drum scraper dryer 1 and becomes low-temperature hot water. It then exchanges heat with the heat exchange medium that absorbed heat in the first heat exchange cycle through the second heat exchanger 52. The heat exchange medium releases heat in the second heat exchanger 52, and the low-temperature hot water becomes high-temperature hot water and returns to the water jacket 11 of the drum scraper dryer 1 to provide heat to the material inside.

[0064] Specifically, as an optional implementation method in this embodiment, such as Figure 1 As shown, an electric auxiliary heater 71 is installed on the second circulation pipeline.

[0065] Specifically, as an optional implementation method in this embodiment, such as Figure 1 As shown, the third heat exchange cycle includes a first heat exchanger 51, a second heat exchanger 52, a compressor 81, a third circulation pipeline, and a throttle valve 82.

[0066] The compressor 81 and the throttle valve 82 are installed on the second circulation pipeline, which is connected to the cavity of the first heat exchanger 51 and the cavity of the second heat exchanger 52, respectively.

[0067] The heat exchange medium in the third circulation pipeline is a mixture of refrigerants of types R410A, R452B, and R454B.

[0068] The energy cycle of the heat exchange medium is as follows: after absorbing heat from the high-temperature water in the first heat exchange cycle in the first heat exchanger 51, the heat exchange medium is transformed into a high-temperature and high-pressure gas by the compressor 81. After heating the low-temperature hot water in the second heat exchange cycle in the second heat exchanger 52, it becomes a low-temperature and low-pressure liquid. After passing through the throttle valve 82, it returns to the first heat exchange cycle to absorb heat from the high-temperature water in the first heat exchange cycle.

[0069] During the start-up and shutdown phases of the drum scraper dryer, electric auxiliary heating 71 is used to heat the low-temperature hot water in the jacket, thereby avoiding the problem of insufficient secondary steam during the start-up phase, which leads to insufficient heat provided by the first heat exchanger 51 to the heat exchange medium. During the shutdown phase, starting electric auxiliary heating 71 can fully ensure that after the boiling point of the material is concentrated, the lack of sufficient heat will prevent the water molecules with low evaporation rate in the innermost layer of the material from evaporating, thus causing the dry material to have an excessively high moisture content.

[0070] Taking a feed rate of 5t / d as an example, the specific working method of this utility model is as follows:

[0071] The second heat exchange cycle is started, and the water jacket 11 is heated by the electric auxiliary heater 71. When the heating temperature rises to 55-65℃, the material is fed into the drying chamber. The feeding rate is 250-300 kg / h.

[0072] Start vacuum pump 4 and control the vacuum degree to 82-88%. Vacuum pump 4 draws the steam in the drying chamber into the steam condensing chamber 2 for condensation. The condensate is drawn into the condensate tank 3.

[0073] Start the first heat exchange cycle, adjust the flow rate of the heat exchange medium in the circulating pump 62 so that the temperature range of the medium entering the condenser 61 is 30-40℃ and the temperature range of the medium exiting the condenser 61 is controlled at 40-50℃; the temperature range of the medium entering the first heat exchanger 51 is controlled at 40-50℃ and the temperature range of the medium exiting the first heat exchanger 51 is controlled at 30-40℃.

[0074] The third heat exchange cycle is started by starting the compressor 81 and the throttle valve 82, controlling the temperature range of the heat exchange medium entering the first heat exchanger 51 to be 25-30℃, and the temperature range of the heat exchange medium exiting the first heat exchanger 51 to be 35-45℃; after the compressor 81 does work, the temperature is controlled to be 90-100℃.

[0075] Stop the electric auxiliary heating 71. In the second heat exchange cycle, the temperature range of the hot water entering the second heat exchanger 52 is controlled at 55-65℃. After heat exchange with the second heat exchanger 52, the temperature range of the hot water exiting the second heat exchanger 52 is controlled at 75-85℃.

[0076] The liquid level of the condensate tank is controlled within the range of 30% to 80% by interlocking the water pump 31 and the liquid level of the condensate tank.

[0077] The rotation speed of the scraper in the drum scraper dryer 1 is controlled at 4 to 10 rpm. After the dry material is discharged, the moisture content is tested and controlled to be within 10% by adjusting the rotation speed.

[0078] When the feeding is completely finished, the boiling point of the material in the drum scraper dryer 1 increases and the secondary steam gradually decreases, the electric auxiliary heating 71 is started again to keep the temperature of the hot water entering the water jacket 11 in the second heat exchange cycle not lower than 80°C.

[0079] Finally, stop compressor 81, close throttle valve 82, and stop the third heat exchange cycle;

[0080] Stop circulating pump 62 and stop the first heat exchange cycle;

[0081] Stop the electric auxiliary heating 71 and stop the second heat exchange cycle;

[0082] Once all the dry material in the drum scraper dryer 1 has been discharged, the vacuum pump 4 is stopped.

[0083] The components of each device selected in this application that do not specify a particular structure are all general standard parts or parts known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0084] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0085] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0086] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0087] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0088] In addition, in the various embodiments of this utility model, each functional unit can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0089] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A three-cycle low-temperature scraper drying system for high-salt wastewater, characterized in that, include The dryer consists of a drum scraper dryer (1), a steam condensing chamber (2), a condensate tank (3), and a vacuum pump (4). The steam condensing chamber (2) is connected to the drying chamber of the drum scraper dryer (1). The condensate tank (3) is connected to the condensate outlet of the steam condensing chamber (2). The outlet of the condensate tank (3) is connected to a water pump (31). The vacuum pump (4) is connected to the condensate tank (3). The vacuum pump (4) evacuates the drying chamber through the condensate tank (3) and the steam condensing chamber (2). The first heat exchange cycle has one heat exchange end connected to the steam condenser (2) and the other heat exchange end connected to the third heat exchange cycle. The first heat exchange cycle is adapted to exchange the heat absorbed by the steam condenser (2) to the third heat exchange cycle. The second heat exchange cycle has one heat exchange end connected to the water jacket (11) of the drum scraper dryer (1) and the other heat exchange end connected to the third heat exchange cycle. The second heat exchange cycle is adapted to exchange the heat of the third heat exchange cycle to the water jacket (11). The third heat exchange cycle has its two heat exchange ends connected to the first and second heat exchange cycles, respectively.

2. The three-cycle high-salt wastewater low-temperature scraper drying system according to claim 1, characterized in that, The first heat exchange cycle includes a condenser (61), a first heat exchanger (51), a first circulation pipeline, and a circulation pump (62); The condenser (61) is installed in the steam condensation chamber (2), and the condenser (61) and the shell cavity of the first heat exchanger (51) form a first circulation pipeline, and the circulation pump (62) is installed on the first circulation pipeline.

3. The three-cycle high-salt wastewater low-temperature scraper drying system according to claim 1, characterized in that, The second heat exchange cycle includes a second heat exchanger (52) and a second circulation pipeline; The second circulation pipeline connects the water jacket (11) and the shell cavity of the second heat exchanger (52).

4. The three-cycle high-salt wastewater low-temperature scraper drying system according to claim 3, characterized in that, An electric auxiliary heater (71) is installed on the second circulation pipeline.

5. The three-cycle high-salt wastewater low-temperature scraper drying system according to claim 1, characterized in that, The third heat exchange cycle includes a first heat exchanger (51), a second heat exchanger (52), a compressor (81), a third circulation pipeline, and a throttle valve (82); The compressor (81) and the throttle valve (82) are installed on the second circulation pipeline, which is connected to the cavity of the first heat exchanger (51) and the cavity of the second heat exchanger (52) respectively.

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