MVR evaporation system

Abstract

The utility model discloses an MVR (mechanical vapor recompression) evaporation system which comprises a first-effect circulating pump, a first-effect heater, a first-effect separator, a first-effect material transfer pump, a second-effect separator, a second-effect circulating pump, a second-effect heater and a vapor compressor. The second-effect circulating pump, the tube pass of the second-effect heater and the second-effect separator are connected through a pipeline to form a second-effect evaporation circulating unit, the first-effect evaporation circulating unit is connected to the second-effect evaporation circulating unit through a pipeline, and a steam outlet of the first-effect separator and a steam outlet of the second-effect separator are connected to the steam compressor through pipelines. An outlet of the steam compressor is connected to shell sides of the first-effect heater and the second-effect heater through pipelines. Under the condition that the thermal load is not changed, the average effective heat transfer temperature difference is increased by about 20%, and the total heat exchange area is reduced by about 20%; the average boiling point temperature rise is reduced by about 6%, scaling of the separator can be slowed down, and operation flexibility is improved.

Description

Technical Field

[0001] The utility model is used in the technical field of evaporation and concentration, in particular to an MVR evaporation system. Background Art

[0002] Evaporation and concentration are typical chemical unit operations in process industries. Research and optimization of efficient and energy-saving evaporation and concentration technologies can bring significant social and economic benefits. Mechanical vapor recompression technology (MVR) refers to the use of a steam compressor to compress the secondary steam generated by evaporation, increase the temperature and pressure of the secondary steam, and increase the thermal enthalpy of the secondary steam. Subsequently, these high-temperature and high-pressure secondary steam are sent to the heater for condensation to heat the raw material liquid, thereby maintaining the raw material liquid in a boiling state. Except for the need to supplement additional fresh steam when starting the car, no fresh steam is required during the evaporation process. This method consumes a small amount of electricity and maximizes the recovery and utilization of the latent heat of the secondary steam. It is efficient and energy-saving and is one of the most advanced evaporation and concentration technologies currently available.

[0003] In the prior art, the single-effect MVR system mainly has the following problems: 1. For a single-effect MVR system with an evaporation capacity greater than or equal to 20 t / h, the separator diameter is greater than or equal to 3.2 meters. As a transportation equipment greater than 2.5 meters and non-disassembled, its ordinary road transportation is easily restricted; 2. For a highly concentrated single-effect MVR system, the boiling point temperature rise is high and the average effective heat transfer temperature difference is low, resulting in a large total heat exchange area of ​​the heater; 3. Due to the high boiling point temperature rise, a single separator is prone to scaling, which reduces operational flexibility. Utility Model Content

[0004] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art and to provide an MVR evaporation system.

[0005] The technical solution adopted by the utility model to solve its technical problems is:

[0006] An MVR evaporation system comprises a first-effect circulation pump, a first-effect heater, a first-effect separator, a first-effect material transfer pump, a second-effect separator, a second-effect circulation pump, a second-effect heater and a steam compressor, wherein the first-effect circulation pump, the tube side of the first-effect heater and the first-effect separator are connected through a pipeline to form a first-effect evaporation circulation unit, the second-effect circulation pump, the tube side of the second-effect heater and the second-effect separator are connected through a pipeline to form a second-effect evaporation circulation unit, the first-effect evaporation circulation unit is connected to the second-effect evaporation circulation unit through a pipeline provided with the first-effect material transfer pump, the steam outlet of the first-effect separator and the steam outlet of the second-effect separator are connected to the steam compressor through a pipeline, and the outlet of the steam compressor is connected to the shell side of the first-effect heater and the second-effect heater through a pipeline.

[0007] In combination with the above implementations, in some implementations, the first-effect separator has a first circulation outlet, a first circulation inlet and a first liquid outlet, the first circulation outlet is connected to the first-effect circulation pump through a pipeline, the first-effect circulation pump is connected to the pipe side inlet of the first-effect heater through a pipeline, and the pipe side outlet of the first-effect heater is connected to the first circulation inlet through a pipeline.

[0008] In combination with the above implementations, in some implementations, the second-effect separator has a second circulation outlet, a second circulation inlet and a second liquid outlet, the second circulation outlet is connected to the second-effect circulation pump through a pipeline, the second-effect circulation pump is connected to the tube side inlet of the second-effect heater through a pipeline, and the tube side outlet of the second-effect heater is connected to the second circulation inlet through a pipeline.

[0009] In combination with the above implementations, in some implementations, the second-effect separator has a second-effect feed inlet, the first-effect separator is provided with a first liquid return port, the first liquid outlet is connected to the first-effect material transfer pump through a pipeline, the first-effect material transfer pump is connected to the pipeline and forms a first branch and a second branch, the first branch is connected to the first liquid return port, and the second branch is connected to the second-effect feed inlet.

[0010] In combination with the above implementations, in certain implementations, the second-effect separator has a second liquid return port, the second liquid outlet is connected to the second-effect discharge pump through a pipeline, the second-effect discharge pump is connected to the pipeline and forms a third branch and a fourth branch, the third branch is connected to the second liquid return port, and the fourth branch is connected to the crystallization kettle.

[0011] In combination with the above implementations, in some implementations, the first-effect heater, the first-effect separator, the second-effect separator, and the second-effect heater all have a fresh steam inlet, and the steam outlet of the first-effect heater is connected to the first-effect separator through a steam pipe.

[0012] In combination with the above implementations, in some implementations, the first-effect evaporation circulation unit is connected to a liquid inlet pipeline, and the liquid inlet pipeline is provided with a preheater.

[0013] In combination with the above implementations, in some implementations, the shell side of the first-effect heater is connected to the distilled water tank through a pipeline, the shell side of the second-effect heater is connected to the distilled water tank through a pipeline, and the distilled water tank is connected to the shell side of the preheater through a distilled water pump and a pipeline.

[0014] In combination with the above implementations, in certain implementations, the distilled water tank is connected to the outlet of the steam compressor via a distilled water pump and a pipeline.

[0015] In combination with the above implementations, in certain implementations, the liquid inlet pipeline is provided with a first filter and a second filter connected in parallel at the inlet.

[0016] One of the above technical solutions has at least one of the following advantages or beneficial effects: the technical solution of the utility model adopts a single-effect evaporation circulation unit + a double-effect evaporation circulation unit, wherein the first-effect heater and the second-effect heater are connected in parallel relative to the secondary steam, and the first-effect separator and the second-effect separator are connected in parallel relative to the secondary steam, and cooperate with the steam compressor to form a parallel double-effect MVR; the temperature rise of its steam compressor is about 20°C, the single-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 13°C plus provide a heat transfer temperature difference of about 7°C, and the second-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 15°C plus provide a heat transfer temperature difference of about 5°C; its average boiling point temperature rise is about 14°C, and its average heat transfer temperature difference is about 6°C. Therefore, under the condition of unchanged heat load, the average effective heat transfer temperature difference increases by about 20%, and the total heat exchange area is reduced by about 20%; the average boiling point temperature rise is reduced by about 6%, which can slow down the scaling of the separator and increase the operational flexibility.

[0017] In addition, by adopting parallel double-effect MVR, the volume of a single separator can be reduced, avoiding restrictions on ordinary road transportation.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0020] Figure 1 It is a schematic structural diagram of an embodiment of the utility model. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0022] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0023] In the present utility model, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself. In the description of the present utility model, if there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected or electrically connected or able to communicate with each other; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0025] See also Figure 1 The embodiment of the utility model provides an MVR evaporation system, including a first-effect circulation pump 1, a first-effect heater 2, a first-effect separator 3, a first-effect material transfer pump 4, a second-effect separator 5, a second-effect circulation pump 6, a second-effect heater 7 and a steam compressor 8. The first-effect circulation pump 1 and the tube side of the first-effect heater 2 are connected with the first-effect separator 3 through a pipeline to form a first-effect evaporation circulation unit. The second-effect circulation pump 6 and the tube side of the second-effect heater 7 are connected with the second-effect separator 5 through a pipeline to form a second-effect evaporation circulation unit. The first-effect evaporation circulation unit is connected to the second-effect evaporation circulation unit through a pipeline provided with the first-effect material transfer pump 4. The steam outlet of the first-effect separator 3 and the steam outlet of the second-effect separator 5 are connected to the steam compressor 8 through a pipeline. The outlet of the steam compressor 8 is connected to the shell side of the first-effect heater 2 and the second-effect heater 7 through a pipeline.

[0026] During operation, the raw material liquid first enters the first-effect evaporation circulation unit, and after mixing with part of the first-effect concentrated solution from the first-effect separator 3, it is connected to the tube side of the first-effect heater 2 through a pipeline from the first-effect circulation pump 1 for heating; the mixed solution heated by the first-effect heater 2 is connected to the first-effect separator 3 through a pipeline for first-effect evaporation concentration; the first-effect concentrated solution is connected to the first-effect transfer pump 4 through a pipeline from the first-effect separator 3 for pressurized transportation; the pressurized first-effect concentrated solution is connected to the second-effect evaporation circulation unit through a pipeline from the first-effect transfer pump 4 for second-effect evaporation concentration; during this period, the second-effect concentrated solution is connected to the second-effect circulation pump 6 through a pipeline from the second-effect separator 5 for pressurized transportation; the pressurized second-effect concentrated solution is connected to the tube side of the second-effect heater 7 from the second-effect circulation pump 6 for heating, and then returned to the second-effect separator 5 through a pipeline connection. The secondary steam generated by the first-effect separator 3 and the secondary steam generated by the second-effect separator 5 are connected to the inlet of the steam compressor 8 through a pipeline, and the secondary steam is compressed to increase the temperature and pressure of the secondary steam and increase the thermal enthalpy of the secondary steam. The compressed secondary steam is connected to the shell side of the first effect heater 2 and the second effect heater 7 through a pipeline from the outlet of the steam compressor 8, and serves as a heat source for the evaporation system to heat the first effect concentrated solution and the second effect concentrated solution in forced circulation.

[0027] Traditional single-effect MVR generally uses a heater, a separator, and a steam compressor. The temperature rise of the steam compressor is about 20°C, which is mainly used to overcome the boiling point temperature rise of about 15°C and provide a heat transfer temperature difference of about 5°C. The technical solution of the utility model adopts a single-effect evaporation circulation unit + a double-effect evaporation circulation unit, in which the first-effect heater 2 and the second-effect heater 7 are connected in parallel with respect to the secondary steam, and the first-effect separator 3 and the second-effect separator 5 are connected in parallel with respect to the secondary steam, and cooperate with the steam compressor 8 to form a parallel double-effect MVR; the temperature rise of the steam compressor 8 is about 20°C, the first-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 13°C and provide a heat transfer temperature difference of about 7°C, and the second-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 15°C and provide a heat transfer temperature difference of about 5°C; its average boiling point temperature rise is about 14°C, and its average heat transfer temperature difference is about 6°C. Therefore, under the condition of unchanged heat load, if the average effective heat transfer temperature difference increases by about 20%, the total heat exchange area decreases by about 20%; the average boiling point temperature rise decreases by about 6%, which can slow down the scaling of the separator and increase the operational flexibility.

[0028] In addition, by adopting parallel double-effect MVR, the diameter of a single separator device can be reduced, avoiding restrictions on ordinary road transportation.

[0029] Through quantitative comparative analysis, the MVR evaporation process parameters were optimized; for MVR evaporation systems with an evaporation capacity greater than or equal to 20t / h and high concentration, the parallel double-effect MVR system is compared with the single-effect MVR system: the single separator with a diameter of 3.2 meters is optimized into two separators with a diameter of 2.4 meters to avoid restrictions on ordinary road transportation; under the condition of unchanged total heat load, the average effective heat transfer temperature difference increases by more than 20%, and the total heat exchange area decreases by more than 20%, making the equipment more economical and energy-saving; due to the reduction in the average boiling point temperature rise, the scaling of the separator is slowed down and the operational flexibility is increased.

[0030] In some embodiments, see Figure 1 The first-effect separator 3 has a first circulation outlet 9, a first circulation inlet 10 and a first liquid outlet 11. The first circulation outlet 9 is connected to the first-effect circulation pump 1 through a pipeline. The first-effect circulation pump 1 is connected to the tube side inlet of the first-effect heater 2 through a pipeline. The tube side outlet of the first-effect heater 2 is connected to the first circulation inlet 10 through a pipeline. The raw material liquid enters the first-effect evaporation circulation unit between the first circulation outlet 9 and the first-effect circulation pump 1. After the raw material liquid and the part of the first-effect concentrated solution from the first-effect separator 3 are mixed, the first-effect circulation pump 1 is connected to the tube side of the first-effect heater 2 through a pipeline for heating. The mixed solution heated by the first-effect heater 2 is connected to the first-effect separator 3 through a pipeline for first-effect evaporation and concentration. In this embodiment, the raw material liquid and the part of the first-effect concentrated solution of the first-effect separator 3 are mixed better, ensuring better heat exchange and evaporation effects. The first-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 13°C and provide a heat transfer temperature difference of about 7°C.

[0031] For further information, see Figure 1 The second-effect separator 5 has a second circulation outlet 12, a second circulation inlet 13 and a second liquid outlet 14. The second circulation outlet 12 is connected to the second-effect circulation pump 6 through a pipeline. The second-effect circulation pump 6 is connected to the pipe side inlet of the second-effect heater 7 through a pipeline. The pipe side outlet of the second-effect heater 7 is connected to the second circulation inlet 13 through a pipeline. Part of the second-effect concentrated solution is connected to the second-effect circulation pump 6 through a pipeline from the second-effect separator 5 for pressurized transportation; the pressurized part of the second-effect concentrated solution is connected to the pipe side of the second-effect heater 7 from the second-effect circulation pump 6 through a pipeline for heating, and then returned to the second-effect separator 5 through a pipeline connection. The second-effect evaporation circulation unit is mainly used to overcome the boiling point temperature rise of about 15°C and provide a heat transfer temperature difference of about 5°C.

[0032] For further information, see Figure 1, the second-effect separator 5 has a second-effect feed port 15, the first-effect separator 3 is provided with a first liquid return port 16, the first liquid outlet 11 is connected to the first-effect transfer pump 4 through a pipeline, the first-effect transfer pump 4 is connected to the pipeline and forms a first branch and a second branch, the first branch is connected to the first liquid return port 16, and the second branch is connected to the second-effect feed port 15. After the first-effect evaporation concentration, part of the first-effect concentrated solution is connected to the first-effect transfer pump 4 from the first-effect separator 3 through a pipeline for pressurized transportation; part of the first-effect concentrated solution that has been pressurized returns to the first-effect separator 3 from the first-effect transfer pump 4 through a pipeline connection; another part of the first-effect concentrated solution that has been pressurized is connected to the second-effect separator 5 from the first-effect transfer pump 4 through a pipeline for second-effect evaporation concentration.

[0033] In some embodiments, see Figure 1 The second effect separator 5 has a second liquid return port 17, and the second liquid outlet 14 is connected to the second effect discharge pump 18 through a pipeline. The second effect discharge pump 18 is connected to the pipeline to form a third branch and a fourth branch. The third branch is connected to the second liquid return port 17, and the fourth branch is connected to the crystallization kettle. Part of the second effect concentrated solution is connected to the second effect discharge pump 18 through a pipeline from the second effect separator 5 for pressurized transportation; the pressurized part of the second effect concentrated solution is returned to the second effect separator 5 from the second effect discharge pump 18 through a pipeline connection; the other part of the pressurized second effect concentrated solution is connected to the downstream crystallization kettle from the second effect discharge pump 18 through a pipeline for solid-liquid separation and material crystallization.

[0034] In some embodiments, see Figure 1 The first-effect heater 2, the first-effect separator 3, the second-effect separator 5, and the second-effect heater 7 all have fresh steam inlets, which are used as the heat source input when the system is started up and preheated, and do not need to be connected during normal operation. Among them, the steam outlet of the first-effect heater 2 is connected to the first-effect separator 3 through a steam pipeline, which is mainly used to prevent compressor surge when the system is started up, and does not need to be connected during normal operation.

[0035] In some embodiments, see Figure 1 The first-effect evaporation circulation unit is connected to the liquid inlet pipeline, and the liquid inlet pipeline is provided with a preheater 19. The raw material liquid is connected to the pipe side of the preheater 19 through the pipeline for preheating and temperature increase.

[0036] For further information, see Figure 1The shell side of the first-effect heater 2 is connected to the distilled water tank 20 through a pipeline, and the shell side of the second-effect heater 7 is connected to the distilled water tank 20 through a pipeline. The compressed secondary steam releases latent heat and becomes distilled water. The distilled water is connected to the distilled water tank 20 through a pipeline from the shell side of the first-effect heater 2 and the second-effect heater 7 for buffering. The distilled water tank 20 is connected to the shell side of the preheater 19 through a distilled water pump 21 and a pipeline. The buffered distilled water is connected to the shell side of the preheater 19 from the distilled water tank 20 through a distilled water pump 21 and a pipeline as a heat source for the preheater 19, wherein the raw material liquid flows through the pipe side of the preheater 19 before entering the first-effect circulation pump 1 to be preheated and heated, and the waste heat of the distilled water is recovered.

[0037] In some embodiments, see Figure 1 The distilled water tank 20 is connected to the outlet of the steam compressor 8 through a distilled water pump 21 and a pipeline, and is vaporized after mixing with the secondary steam to control the temperature of the secondary steam.

[0038] In some embodiments, see Figure 1 The liquid inlet pipeline is provided with a first filter 22 and a second filter 23 connected in parallel at the inlet. The raw liquid from the boundary zone is connected to the first filter 22 and the second filter 23 through a pipeline for solid-liquid separation pretreatment, wherein the first filter 22 and the second filter 23 are standby for each other and can be disassembled and cleaned. After the solid-liquid separation pretreatment, it is connected to the pipe side of the preheater 19 through a pipeline for preheating and temperature rise.

[0039] In the description of this specification, the description with reference to the terms "example", "embodiment" or "some embodiments" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0040] Of course, the invention is not limited to the above-mentioned embodiments, and those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An MVR evaporation system, characterized in that: The invention comprises a first-effect circulation pump, a first-effect heater, a first-effect separator, a first-effect material transfer pump, a second-effect separator, a second-effect circulation pump, a second-effect heater and a steam compressor. The first-effect circulation pump, the tube side of the first-effect heater and the first-effect separator are connected through a pipeline to form a first-effect evaporation circulation unit. The second-effect circulation pump, the tube side of the second-effect heater and the second-effect separator are connected through a pipeline to form a second-effect evaporation circulation unit. The first-effect evaporation circulation unit is connected to the second-effect evaporation circulation unit through a pipeline provided with the first-effect material transfer pump. The steam outlet of the first-effect separator and the steam outlet of the second-effect separator are connected to the steam compressor through a pipeline. The outlet of the steam compressor is connected to the shell side of the first-effect heater and the second-effect heater through a pipeline.

2. The MVR evaporation system according to claim 1, characterized in that: The first-effect separator has a first circulation outlet, a first circulation inlet and a first liquid outlet, the first circulation outlet is connected to the first-effect circulation pump through a pipeline, the first-effect circulation pump is connected to the tube side inlet of the first-effect heater through a pipeline, and the tube side outlet of the first-effect heater is connected to the first circulation inlet through a pipeline.

3. The MVR evaporation system according to claim 2, characterized in that: The second-effect separator has a second circulation outlet, a second circulation inlet and a second liquid outlet, the second circulation outlet is connected to the second-effect circulation pump through a pipeline, the second-effect circulation pump is connected to the tube side inlet of the second-effect heater through a pipeline, and the tube side outlet of the second-effect heater is connected to the second circulation inlet through a pipeline.

4. The MVR evaporation system according to claim 3, characterized in that: The second-effect separator has a second-effect feed inlet, and the first-effect separator is provided with a first liquid return port. The first liquid outlet is connected to the first-effect material transfer pump through a pipeline. The first-effect material transfer pump is connected to the pipeline to form a first branch and a second branch. The first branch is connected to the first liquid return port, and the second branch is connected to the second-effect feed inlet.

5. The MVR evaporation system according to claim 3, characterized in that: The second-effect separator has a second liquid return port, the second liquid outlet is connected to the second-effect discharge pump through a pipeline, the second-effect discharge pump is connected to the pipeline to form a third branch and a fourth branch, the third branch is connected to the second liquid return port, and the fourth branch is connected to the crystallization kettle.

6. The MVR evaporation system according to claim 1, characterized in that: The first-effect heater, the first-effect separator, the second-effect separator and the second-effect heater all have a fresh steam inlet, and the steam outlet of the first-effect heater is connected to the first-effect separator through a steam pipeline.

7. The MVR evaporation system according to claim 1, characterized in that: The first-effect evaporation circulation unit is connected to a liquid inlet pipeline, and the liquid inlet pipeline is provided with a preheater.

8. The MVR evaporation system according to claim 7, characterized in that: The shell side of the first-effect heater is connected to the distilled water tank through a pipeline, the shell side of the second-effect heater is connected to the distilled water tank through a pipeline, and the distilled water tank is connected to the shell side of the preheater through a distilled water pump and a pipeline.

9. The MVR evaporation system according to claim 8, characterized in that: The distilled water tank is connected to the outlet of the steam compressor through a distilled water pump and a pipeline.

10. The MVR evaporation system according to claim 7, characterized in that: The liquid inlet pipeline is provided with a first filter and a second filter connected in parallel at the inlet.

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