A heat pump thermal coupling recovery system for DMF wastewater

Abstract

The present invention discloses a heat pump thermal coupling recovery system for DMF wastewater, which relates to the technical field of wastewater treatment. It includes two sets of technological processes, namely Process 1 and Process 2. For the two different technological processes, according to the different concentrations of DMF wastewater, the relative positions of the heat pump refining system and the heat pump compressor and the thermal coupling refining system are different; both Process 1 and Process 2 include Thermal Coupling Refining System I, Thermal Coupling Refining System II, and Thermal Coupling Refining System III; in Process 1, the heat pump compressor is located between Thermal Coupling Refining System II and Thermal Coupling Refining System III; in Process 2, the heat pump refining system and the heat pump compressor are located between Thermal Coupling Refining System I and Thermal Coupling Refining System II; the present invention can treat DMF wastewater with various concentrations, and has low investment, less power consumption, simple operation, stable operation and a long cycle, can save steam, greatly reduce the construction cost, and can recover water while recovering DMF.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and specifically to a heat pump thermal coupling recovery system for DMF wastewater. Background Art

[0002] Dimethylformamide (DMF), as an important chemical raw material and a solvent with excellent properties, is mainly used in various chemical industries. Due to its unique physical properties, it can dissolve most organic substances and many inorganic substances, so it is widely used as a solvent. However, wastewater containing DMF is often produced during production. Such wastewater has characteristics such as unpleasant smell, strong toxicity, and stable properties. If it is directly discharged into the environment without effective treatment, it will surely bring great harm to people's work and life.

[0003] At present, in the market for the treatment of DMF wastewater, the heat coupling refining system, the heat pump refining system, and the cooperation of the heat pump compressor are mainly used to gradually purify and recover DMF. Common methods include the triple-effect process and the heat pump + double-effect process. However, such processes consume a large amount of thermal steam. Other processes include the three-compressor process. Although this process has better purification efficiency, its construction and maintenance costs are high, it is very power-consuming, and there is also a process where the heat pump is in front and the heat coupling is behind, but it is prone to blockage problems. For the heat pump + dividing wall column process, the cost is also high, the operation is cumbersome, and the recovery rate of DMF finished products is low. In the market, the heat pump concentration process with high recovery rate and high-quality finished products has the problem of only being able to recover DMF finished products.

[0004] In view of the above problems, we provide a heat pump thermal coupling recovery system for DMF wastewater to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of the present invention is to provide a heat pump thermal coupling recovery system for DMF wastewater to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A heat pump thermal coupling recovery system for DMF wastewater includes two sets of process flows, namely Process Flow One and Process Flow Two. Each set of process flow includes a heat coupling refining system, a heat pump refining system, and a heat pump compressor. According to the different concentrations of DMF wastewater in the two different process flows, the relative positions of the heat pump refining system and the heat pump compressor and the heat coupling refining system are different. When the DMF concentration in the wastewater is higher than the preset value, Process Flow One is used for treatment and recovery. When the DMF concentration in the wastewater is lower than the preset value, Process Flow Two is used for treatment and recovery;

[0008] Both Process Flow One and Process Flow Two include Heat Coupling Refining System Ⅰ, Heat Coupling Refining System Ⅱ, and Heat Coupling Refining System Ⅲ;

[0009] The heat pump refining system and the heat pump compressor in Process I are located between the heat-integrated refining system II and the heat-integrated refining system III;

[0010] The heat pump refining system and the heat pump compressor in Process II are located between the heat-integrated refining system I and the heat-integrated refining system II.

[0011] As a further solution of the present invention: Process I specifically includes the following steps:

[0012] Step 1: The DMF-containing wastewater enters the heat-integrated refining system I, and part of the water in the wastewater is removed in the form of top steam I at the top of the column;

[0013] Step 2: The crude DMF at the bottom of the heat-integrated refining system I enters the heat-integrated refining system II, and part of the water in the wastewater is removed in the form of top steam II at the top of the column. At the same time, the top steam II is used as a heat source to heat the heat-integrated refining system I, and the heat is coupled here and reused twice;

[0014] Step 3: The crude DMF at the bottom of the heat-integrated refining system II enters the heat pump refining system, and part of the water in the wastewater is removed in the form of heat pump top steam;

[0015] Step 4: The heat pump top steam is compressed by the heat pump compressor and used to heat the heat pump refining system. The heat is recycled here to achieve the purpose of energy saving;

[0016] Step 5: The crude DMF at the bottom of the heat pump refining system enters the heat-integrated refining system III, and part of the water in the wastewater is removed in the form of top steam III at the top of the column. At the same time, the top steam III is used as a heat source to heat the heat-integrated refining system II, and the heat is coupled here and reused three times;

[0017] Step 6: The DMF product is discharged from the bottom of the heat-integrated refining system III.

[0018] As a further solution of the present invention: Process II specifically includes the following steps:

[0019] Step 1: The DMF-containing wastewater enters the heat-integrated refining system I, and part of the water in the wastewater is removed in the form of top steam I at the top of the column;

[0020] Step 2: The crude DMF at the bottom of the heat-integrated refining system I enters the heat pump refining system, and part of the water in the wastewater is removed in the form of heat pump top steam;

[0021] Step 3: The heat pump top steam is compressed by the heat pump compressor and used to heat the heat pump refining system. The heat is recycled here to achieve the purpose of energy saving;

[0022] Step 4: The crude DMF at the bottom of the heat pump refining system enters the heat-integrated refining system II, and part of the water in the wastewater is removed in the form of overhead vapor II at the top of the tower. At the same time, the overhead vapor II is used as a heat source to heat the heat-integrated refining system I, and the heat is coupled here and reused twice.

[0023] Step 5: The crude DMF at the bottom of the heat-integrated refining system II enters the heat-integrated refining system III, and the remaining water in the wastewater is removed in the form of overhead vapor III at the top of the tower. At the same time, the overhead vapor III is used as a heat source to heat the heat-integrated refining system II, and the heat is coupled here and reused three times.

[0024] Step 6: The finished DMF is discharged from the bottom of the heat-integrated refining system III.

[0025] As a further solution of the present invention: The preset value is: the DMF concentration range in the wastewater is 15% - 30%, preferably 25%.

[0026] As a further solution of the present invention: Before the said process one and the said process two, there is also a detection device for detecting the DMF concentration in the wastewater.

[0027] As a further solution of the present invention: The said process one and the said process two are equipped with a guiding component for guiding the corresponding DMF wastewater into different technological processes in cooperation with the said detection device.

[0028] As a further solution of the present invention: The heat-integrated refining system includes a dehydration tower I, a dehydration tower II and a rectification tower, as well as a reboiler for the dehydration tower I, a reboiler for the dehydration tower II and a reboiler for the rectification tower. The heat pump refining system includes an MVR dehydration tower, an MVR dehydration tower falling film evaporator, a compressor and a forced circulation pump.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. Compared with the traditional triple-effect process, the present process can save more than 50% of the steam volume.

[0031] 2. Compared with the heat pump + double-effect process, the present process can save more than 30% of the steam.

[0032] 3. Compared with the three-compressor process, the present process can treat DMF wastewater with various concentrations, and has low investment, low power consumption, simple operation, stable operation and long cycle.

[0033] 4. Compared with the process with a heat pump in the front and a heat integration in the back, the present process has a long operation cycle and is not easily blocked.

[0034] 5. Compared with the heat pump + dividing wall column process, the present process has low equipment investment, simple operation, stable operation, low decomposition rate and high recovery rate.

[0035] 6. Compared with the separate heat pump concentration process, this process can produce DMF finished products and recycle intermediate water. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the process flow diagram of Process 1 in the present invention.

[0037] Figure 2 It is the process flow diagram of Process 2 in the present invention.

[0038] Figure 3 It is the calculation process diagram for determining the position of the heat pump refining system.

[0039] Figure 4 It is the calculation process diagram for determining the position of the heat pump refining system in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] Please refer to Figures 1-4 , in the embodiments of the present invention, a heat pump thermal coupling recovery system for DMF wastewater includes two sets of process flows, namely Process 1 and Process 2. Each set of processes includes a thermal coupling refining system, a heat pump refining system, and a heat pump compressor. The relative positions of the heat pump refining system and the heat pump compressor and the thermal coupling refining system in the two different process flows are different according to the different concentrations of DMF wastewater. When the DMF concentration in the wastewater is high, Process 1 is used for treatment and recovery, and when the DMF concentration in the wastewater is low, Process 2 is used for treatment and recovery;

[0042] Both Process 1 and Process 2 include a thermal coupling refining system I, a thermal coupling refining system II, and a thermal coupling refining system III;

[0043] The heat pump compressor in Process 1 is located between the thermal coupling refining system II and the thermal coupling refining system III;

[0044] The heat pump refining system and the heat pump compressor in Process 2 are located between the thermal coupling refining system I and the thermal coupling refining system II.

[0045] As a further solution of the present invention: Process 1 specifically includes the following steps:

[0046] Step 1: The wastewater containing DMF enters the thermal coupling refining system I, and part of the water in the wastewater is removed in the form of top steam I here;

[0047] Step 2: The crude DMF at the bottom of the thermal coupling refining system I enters the thermal coupling refining system II. Part of the water in the wastewater is removed in the form of overhead vapor II at the top of the column. At the same time, the overhead vapor II is used as a heat source to heat the thermal coupling refining system I, and the heat is coupled here and reused 2 times.

[0048] Step 3: The crude DMF at the bottom of the thermal coupling refining system II enters the heat pump refining system. Part of the water in the wastewater is removed in the form of heat pump overhead vapor.

[0049] Step 4: The heat pump overhead vapor is compressed by a heat pump compressor and then used to heat the heat pump refining system. The heat is recycled here to achieve the purpose of energy conservation.

[0050] Step 5: The crude DMF at the bottom of the heat pump refining system enters the thermal coupling refining system III. Part of the water in the wastewater is removed in the form of overhead vapor III at the top of the column. At the same time, the overhead vapor III is used as a heat source to heat the thermal coupling refining system II, and the heat is coupled here and reused 3 times.

[0051] Step 6: The finished DMF is discharged from the bottom of the thermal coupling refining system III.

[0052] As a further solution of the present invention: The specific steps of the second process are as follows:

[0053] Step 1: The wastewater containing DMF enters the thermal coupling refining system I. Part of the water in the wastewater is removed in the form of overhead vapor I at the top of the column.

[0054] Step 2: The crude DMF at the bottom of the thermal coupling refining system I enters the heat pump refining system. Part of the water in the wastewater is removed in the form of heat pump overhead vapor.

[0055] Step 3: The heat pump overhead vapor is compressed by a heat pump compressor and then used to heat the heat pump refining system. The heat is recycled here to achieve the purpose of energy conservation.

[0056] Step 4: The crude DMF at the bottom of the heat pump refining system enters the thermal coupling refining system II. Part of the water in the wastewater is removed in the form of overhead vapor II at the top of the column. At the same time, the overhead vapor II is used as a heat source to heat the thermal coupling refining system I, and the heat is coupled here and reused 2 times. [[ID=3)]

[0057] Step 5: The crude DMF at the bottom of the thermal coupling refining system II enters the thermal coupling refining system III. The remaining water in the wastewater is removed in the form of overhead vapor III at the top of the column. At the same time, the overhead vapor III is used as a heat source to heat the thermal coupling refining system II, and the heat is coupled here and reused 3 times.

[0058] Step 6: The finished DMF is discharged from the bottom of the thermal coupling refining system III.

[0059] As a further aspect of the present invention: the preset value is as follows: the DMF concentration range in the wastewater is 15% - 30%, preferably 25%.

[0060] As a further aspect of the present invention: before the first process and the second process, there is also a detection device for detecting the DMF concentration in the wastewater.

[0061] As a further aspect of the present invention: the first process and the second process are provided with a guiding component for guiding the corresponding DMF wastewater into different technological processes in cooperation with the detection device;

[0062] During operation, the detection device here can also be set as an on - line monitoring system. According to the change of concentration, the system realizes the switching of two technological routes through the switching of valves, pump groups and pipelines.

[0063] As a further aspect of the present invention: the thermally coupled refining system includes a dehydration tower I, a dehydration tower II and a rectification tower, as well as a reboiler for the dehydration tower I, a reboiler for the dehydration tower II and a reboiler for the rectification tower. The heat pump refining system includes an MVR dehydration tower, an MVR dehydration tower falling - film evaporator, a compressor and a forced circulation pump;

[0064] During operation, the thermally coupled refining system is a conventional setting. The difference is that a heat pump refining system is added. The main purposes of adding the heat pump refining system are two: one is energy conservation and consumption reduction, which can save 20% - 30% of steam consumption, and the energy - saving effect is remarkable; the other is production expansion. On the same land area, the production capacity of this process can be doubled compared with the pure thermally coupled process, and the ratio of the processing capacity of the heat pump system to the processing capacity of the thermally coupled system can be adjusted arbitrarily between 0.5 and 1.5.

[0065] Example 1

[0066] For the existing DMF wastewater, after analysis by the detection device, the DMF concentration is about 30%. The concentration limit of the first process and the second process is set at 25%. Therefore, the above - mentioned wastewater is introduced into the first process through the guiding component for recovery treatment operation:

[0067] First, the DMF - containing wastewater enters the thermally coupled refining system I. Part of the water in the wastewater is removed in the form of overhead vapor I at the top of the tower. At this time, the temperature range of the overhead vapor I is between 50 and 80 °C, and the concentration of the DMF crude product in the thermally coupled refining system I is between 20% and 40%;

[0068] Then, the crude DMF at the bottom of the heat-integrated refining system I is transported into the heat-integrated refining system II. Part of the moisture in the wastewater is removed in the form of overhead vapor II at the top of the column. At the same time, the overhead vapor II serves as a heat source to heat the heat-integrated refining system I, and the heat is coupled and reused twice. At this time, the temperature range of the overhead vapor II is between 60 and 80 °C, and the concentration of the crude DMF in the heat-integrated refining system II is between 40% and 60%.

[0069] Next, the crude DMF at the bottom of the heat-integrated refining system II is transported into the heat pump refining system. Part of the moisture in the wastewater is removed in the form of heat pump overhead vapor. After the heat pump overhead vapor is compressed by the heat pump compressor, it heats the heat pump refining system, and the heat is recycled here to achieve the purpose of energy saving. At this time, the temperature of the heat pump overhead vapor is between 70 and 80 °C, the temperature of the compressed steam is between 90 and 120 °C, and the concentration of the crude DMF in the heat pump refining system is between 60% and 80%.

[0070] Then, the crude DMF at the bottom of the heat pump refining system enters the heat-integrated refining system III. Part of the moisture in the wastewater is removed in the form of overhead vapor III at the top of the column. At the same time, the overhead vapor III serves as a heat source to heat the heat-integrated refining system II, and the heat is coupled and reused three times. At this time, the temperature range of the overhead vapor III is between 80 and 120 °C, and the concentration of the crude DMF in the heat-integrated refining system III is greater than 98.5%. The qualified DMF product is discharged from the bottom of the heat-integrated refining system III.

[0071] Example 2

[0072] For the existing DMF wastewater, after analysis by the detection device, the DMF concentration is about 10%. The concentration limits of Process 1 and Process 2 are set at 25%. Therefore, the above wastewater is introduced into Process 2 through the guiding component for recovery treatment operation:

[0073] First, the DMF-containing wastewater enters the heat-integrated refining system I. Part of the moisture in the wastewater is removed in the form of overhead vapor I at the top of the column. At this time, the temperature range of the overhead vapor I is between 50 and 80 °C, and the concentration of the crude DMF in the heat-integrated refining system I is between 20% and 40%.

[0074] Then, the crude DMF at the bottom of the heat-integrated refining system I is transported to the heat pump refining system. Part of the moisture in the wastewater is removed in the form of heat pump overhead vapor. After the heat pump overhead vapor is compressed by the heat pump compressor, it heats the heat pump refining system, and the heat is recycled here to achieve the purpose of energy saving. At this time, the temperature of the heat pump overhead vapor is between 70 and 80 °C, the temperature of the compressed steam is between 90 and 120 °C, and the concentration of the crude DMF in the heat pump refining system is between 40% and 60%.

[0075] Next, the crude DMF at the bottom of the heat pump refining system is input into the heat-integrated refining system II. Part of the water in the wastewater is removed in the form of overhead vapor II at the top of the column. At the same time, the overhead vapor II is used as a heat source to heat the heat-integrated refining system I, and the heat is coupled here and reused twice. At this time, the temperature range of the overhead vapor II is between 60 and 80 °C, and the concentration of the crude DMF in the heat-integrated refining system II is between 60% and 80%.

[0076] Finally, the crude DMF at the bottom of the heat-integrated refining system II is transported to the heat-integrated refining system III. The remaining water in the wastewater is removed in the form of overhead vapor III at the top of the column. At the same time, the overhead vapor III is used as a heat source to heat the heat-integrated refining system II, and the heat is coupled here and reused three times. At this time, the temperature range of the overhead vapor III is between 80 and 120 °C, and the concentration of the crude DMF in the heat-integrated refining system III is greater than 98.5%; the qualified DMF finished product is discharged from the bottom of the heat-integrated refining system III.

[0077] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Although this specification is described according to the embodiments, not every embodiment only contains one technical solution. The narrative mode of this specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A heat pump thermal coupling recovery system for DMF wastewater, comprising two sets of process flows, namely Process One and Process Two. Each set of process flow includes a thermal coupling refining system, a heat pump refining system, and a heat pump compressor, and is characterized in that: According to the different concentrations of DMF wastewater in the two different process flows, the relative positions of the heat pump refining system and the heat pump compressor and the thermal coupling refining system are different. When the DMF concentration in the wastewater is higher than or equal to the preset value, Process One is used for treatment and recovery; when the DMF concentration in the wastewater is lower than the preset value, Process Two is used for treatment and recovery. Both Process One and Process Two include Thermal Coupling Refining System I, Thermal Coupling Refining System II, and Thermal Coupling Refining System III. In Process One, the heat pump refining system and the heat pump compressor are located between Thermal Coupling Refining System II and Thermal Coupling Refining System III. In Process Two, the heat pump refining system and the heat pump compressor are located between Thermal Coupling Refining System I and Thermal Coupling Refining System II. Process One specifically includes the following steps: Step One: The DMF-containing wastewater enters Thermal Coupling Refining System I, and part of the water in the wastewater is removed in the form of overhead vapor I at the top of the tower. Step Two: The crude DMF at the bottom of Thermal Coupling Refining System I enters Thermal Coupling Refining System II, and part of the water in the wastewater is removed in the form of overhead vapor II at the top of the tower. At the same time, overhead vapor II is used as a heat source to heat Thermal Coupling Refining System I, and the heat is coupled here and reused 2 times. Step Three: The crude DMF at the bottom of Thermal Coupling Refining System II enters the heat pump refining system, and part of the water in the wastewater is removed in the form of heat pump overhead vapor at the top of the tower. Step Four: The heat pump overhead vapor is compressed by the heat pump compressor and used to heat the heat pump refining system, and the heat is recycled here to achieve the purpose of energy conservation. Step Five: The crude DMF at the bottom of the heat pump refining system enters Thermal Coupling Refining System III, and part of the water in the wastewater is removed in the form of overhead vapor III at the top of the tower. At the same time, overhead vapor III is used as a heat source to heat Thermal Coupling Refining System II, and the heat is coupled here and reused 3 times. Step Six: The DMF finished product is discharged from the bottom of Thermal Coupling Refining System III. Process Two specifically includes the following steps: Step One: The DMF-containing wastewater enters Thermal Coupling Refining System I, and part of the water in the wastewater is removed in the form of overhead vapor I at the top of the tower. Step Two: The crude DMF at the bottom of Thermal Coupling Refining System I enters the heat pump refining system, and part of the water in the wastewater is removed in the form of heat pump overhead vapor at the top of the tower. Step Three: The heat pump overhead vapor is compressed by the heat pump compressor and used to heat the heat pump refining system, and the heat is recycled here to achieve the purpose of energy conservation. Step Four: The crude DMF at the bottom of the heat pump refining system enters Thermal Coupling Refining System II, and part of the water in the wastewater is removed in the form of overhead vapor II at the top of the tower. At the same time, overhead vapor II is used as a heat source to heat Thermal Coupling Refining System I, and the heat is coupled here and reused 2 times. Step Five: The crude DMF at the bottom of Thermal Coupling Refining System II enters Thermal Coupling Refining System III, and the remaining water in the wastewater is removed in the form of overhead vapor III at the top of the tower. At the same time, overhead vapor III is used as a heat source to heat Thermal Coupling Refining System II, and the heat is coupled here and reused 3 times. Step Six: The finished DMF product is discharged from the bottom of the heat-integrated refining system III.

2. The heat pump thermal coupling recovery system for DMF wastewater according to claim 1, wherein The preset value is: the DMF concentration range in the wastewater is 15% - 30%.

3. A heat pump thermal coupling recovery system for DMF wastewater according to claim 1, characterized in that, Before the said Process One and Process Two, there is also a detection device for detecting the DMF concentration in the wastewater.

4. A heat pump thermal coupling recovery system for DMF wastewater according to claim 3, characterized in that, The said Process One and Process Two, in cooperation with the detection device, are provided with a guiding component for guiding the corresponding DMF wastewater into different technological processes.

5. A heat pump thermal coupling recovery system for DMF wastewater according to claim 1, characterized in that, The heat-integrated refining system includes a dehydration column I, a dehydration column II, and a rectification column, as well as a reboiler for the dehydration column I, a reboiler for the dehydration column II, and a reboiler for the rectification column. The heat pump refining system includes an MVR dehydration column, an MVR dehydration column falling film evaporator, a compressor, and a forced circulation pump.

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