MVR (Mechanical Vapor Recompression) double-loop evaporation and concentration system

Abstract

The utility model relates to the technical field of evaporation and concentration processes, in particular to an MVR (mechanical vapor recompression) double-loop evaporation and concentration system which comprises an evaporator, a preheater and a flash tank, the preheater comprises a first preheater and a vacuum preheater; a first preheater switching valve and a vacuum preheater are arranged between the first preheater and the evaporator; the first preheater switching valve and the vacuum preheater are arranged in parallel; a vacuum preheater switching valve is arranged at the feeding hole of the vacuum preheater; the evaporator air inlet is connected with a primary steam pipeline and a secondary steam pipeline in parallel; a discharge hole of the evaporator is connected with the flash tank; a gas outlet of the flash tank is connected with a gas inlet of the compressor through a compressor inlet valve; an air outlet of the compressor is connected with an air inlet of the evaporator through a secondary steam pipeline; when the compressor breaks down, the loop system can guarantee the evaporation and concentration process of the stock solution and guarantee the continuity of the whole production process.

Description

Technical Field

[0001] The utility model relates to the technical field of evaporation concentration processes, in particular to an MVR double-loop evaporation concentration system. Background Art

[0002] At present, the MVR evaporation concentration process can replace the conventional steam multi-effect evaporation, save a large amount of energy and has relatively high economic benefits, so it is widely used in the production fields such as printing and dyeing, food, and medicine. However, the stable operation of the compressor, which is the core component of the MVR evaporation concentration process, is the key to the entire process system. Therefore, the biggest pain point for users is that once the compressor fails, its repair cycle is relatively long, seriously affecting the production process. How to ensure the reliable operation of the system by using steam in the case of compressor failure is an urgent need for users. Summary of the Utility Model

[0003] The purpose of this application is to provide an MVR double-loop evaporation concentration system, aiming to solve the problems in the prior art.

[0004] An embodiment of this application provides an MVR double-loop evaporation concentration system, including an evaporator, a preheater, and a flash tank; the preheater includes a first preheater and a vacuum preheater; the outlet of the first preheater is connected to the inlet of the evaporator; a first preheater switching valve and a vacuum preheater are provided between the inlet of the first preheater and the inlet of the evaporator; the first preheater switching valve and the vacuum preheater are arranged in parallel; a vacuum preheater switching valve is provided at the inlet of the vacuum preheater; a primary steam pipeline and a secondary steam pipeline are arranged in parallel at the inlet of the evaporator; a primary steam valve is provided on the primary steam pipeline; the outlet of the evaporator is connected to the flash tank; the outlet of the flash tank is connected to the inlet of the compressor through a compressor inlet valve; the outlet of the compressor is connected to the inlet of the evaporator through the secondary steam pipeline and a compressor outlet valve; the liquid outlet of the flash tank is connected to the inlet of the evaporator through a reflux pipeline in sequence passing through a circulation pump, a densitometer, and a regulating valve; the outlet of the flash tank is connected to the vacuum preheater through an extraction pipeline; a vacuum pump valve is provided on the extraction pipeline.

[0005] Further, a discharge pipeline is provided between the densitometer and the regulating valve; a discharge valve is provided on the discharge pipeline.

[0006] Further, the condensed water in the evaporator returns to the first preheater through a pipeline in sequence passing through a condensate tank and a condensate pump.

[0007] Further, a vacuum pump is provided at the outlet of the vacuum preheater; the inlet of the vacuum preheater is connected to the extraction pipeline.

[0008] Furthermore, the outlet of the vacuum preheater is connected to the reflux pipeline behind the regulating valve through a pipeline.

[0009] The beneficial effects of the present utility model are as follows: On the basis of the original evaporation and concentration loop, a variety of control valves and vacuum pumps are added to the present utility model. The MVR evaporation process is combined with the once-through steam evaporation process. Even if the compressor fails, the raw liquid can still be evaporated and concentrated by using the once-through steam, ensuring the continuity of the entire production process and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a flow chart of the double-loop evaporation and concentration system of the present utility model.

[0011] In the figure:

[0012] 1. Evaporator; 2. Once-through steam valve; 3. Once-through steam pipeline; 4. First preheater switching valve; 5. First preheater; 6. Condensate pump; 7. Condensate tank; 8. Vacuum pump; 9. Vacuum preheater; 10. Vacuum preheater switching valve; 11. Circulation pump; 12. Density meter; 13. Regulating valve; 14. Flash tank; 15. Vacuum pump valve; 16. Compressor inlet valve; 17. Compressor; 18. Compressor outlet valve; 19. Discharge valve; 20. Discharge pipeline; 21. Reflux pipeline; 22. Secondary steam pipeline; 23. Air extraction pipeline. SPECIFIC EMBODIMENTS

[0013] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0014] Such as Figure 1An MVR double-loop evaporation and concentration system shown in the figure includes an evaporator 1, a preheater, and a flash tank 14; the preheater includes a first preheater 5 and a vacuum preheater 9; the outlet of the first preheater 5 is connected to the inlet of the evaporator 1; a first preheater switching valve 4 and a vacuum preheater 9 are provided between the inlet of the first preheater 5 and the inlet of the evaporator 1; the first preheater switching valve 4 and the vacuum preheater 9 are arranged in parallel; a vacuum preheater switching valve 10 is provided at the inlet of the vacuum preheater 9; a primary steam pipe 3 and a secondary steam pipe 4 are connected in parallel to the inlet of the evaporator 1; a primary steam valve 2 is provided on the primary steam pipe 3; the primary steam pipe 3 is connected to an external steam generator to provide heat for the heating chamber of the evaporator 1; the outlet of the evaporator 1 is connected to the flash tank 14; the outlet of the flash tank 14 is connected to the inlet of the compressor 17 through a compressor inlet valve 16; the outlet of the compressor 17 is connected to the inlet of the evaporator 1 through a secondary steam pipe 22 via a compressor outlet valve 18; the liquid outlet of the flash tank 14 is connected to the inlet of the evaporator 1 through a reflux pipe 21 in sequence passing through a circulation pump 11, a densitometer 12, and a regulating valve 13; the outlet of the flash tank 14 is connected to the vacuum preheater 9 through an extraction pipe 23; a vacuum pump valve 15 is provided on the extraction pipe 23.

[0015] A discharge pipe 20 is provided between the densitometer 12 and the regulating valve 13; a discharge valve 19 is provided on the discharge pipe 20; the concentrated liquid flows into the reflux pipe 21 from the bottom discharge port of the flash tank 14. When the density reaches the production process requirements, the discharge valve 19 will open, and the concentrated liquid enters the subsequent process. However, when the density does not meet the process requirements, the discharge valve 19 will close, and the concentrated liquid is mixed with the original liquid by the circulation pump 11 and the regulating valve 13 and re-enters the evaporator 1 and the flash tank 14 for heating and evaporation until the density meets the process requirements.

[0016] The condensed water in the evaporator 1 returns to the first preheater 5 through a pipe passing through a condensate tank 7 and a condensate pump 6 in sequence.

[0017] A vacuum pump 8 is provided at the outlet of the vacuum preheater 9; the inlet of the vacuum preheater 9 is connected to the extraction pipe 23; the vacuum pump 8 extracts the high-temperature steam generated by the flash tank 14 to preheat the original liquid in the vacuum preheater 9 and simultaneously creates a negative pressure in the flash tank 14.

[0018] The outlet of the vacuum preheater 9 is connected to the reflux pipe 21 behind the regulating valve 13 through a pipe, which can appropriately save the pipe length without changing the medium flow direction and reduce the cost.

[0019] When the compressor 17 is operating normally, the original concentration working circuit of the traditional MVR is as follows: close the primary steam valve 2, the vacuum pump valve 15, the vacuum preheater switching valve 10, and the vacuum pump 8, and open the compressor outlet valve 18, the compressor inlet valve 16, and the first preheater switching valve 4. The raw liquid exchanges heat and is heated up with the high-temperature condensed water generated by the evaporator 1 in the first preheater 5, and then the raw liquid enters the evaporator 1 for heat exchange to reach above 90 °C. It enters the flash tank 14 from the outlet of the evaporator 1. Due to the negative pressure generated by the suction of the compressor 17 inlet, the water in the raw liquid evaporates. The steam generated by the flash tank 14 is heated up and pressurized by the compressor 17 to generate secondary steam and then sent back to the evaporator 1 to heat up the raw liquid, and so on; the concentrated liquid flows out from the bottom outlet of the flash tank 14 and enters the return pipeline 21 for treatment according to the concentration density.

[0020] When the compressor 17 fails, a working circuit combining the MVR evaporation process and the primary steam evaporation process is adopted to continue evaporating and concentrating the raw liquid with primary steam. The specific operation method is as follows: close the compressor outlet valve 18, the compressor inlet valve 16, and the first preheater switching valve 4, and open the primary steam valve 2, the vacuum pump valve 15, the vacuum preheater switching valve 10, and the vacuum pump 8. The raw liquid passes through the first preheater 5, the vacuum preheater switching valve 10, the vacuum preheater 9, and the evaporator 1 and enters the flash tank 14. In this process, the first preheater 5 uses the high-temperature condensed water generated by the evaporator 1 to preheat the raw liquid for the first time, and then flows into the vacuum preheater 9. The vacuum pump 8 sucks the high-temperature gas generated by the flash tank 14 into the vacuum preheater 9 to preheat the raw liquid for the second time, and the gas after heat exchange is discharged by the vacuum pump 8; the raw liquid enters the evaporator 1, and the evaporator 1 heats the raw liquid with primary steam. The heated liquid enters the flash tank 14. Due to the compressor failure, the inside of the flash tank 14 is evacuated by the vacuum pump 8 to generate a negative pressure, resulting in the evaporation of the liquid in the flash tank 14 at a low temperature, thereby obtaining the concentrated raw liquid, which flows into the return pipeline 21 from the bottom liquid outlet of the flash tank 14.

[0021] 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 can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. An MVR double-loop evaporation and concentration system, characterized in that, It includes an evaporator, a preheater and a compressor; the preheater includes a first preheater and a vacuum preheater; the outlet of the first preheater is connected to the inlet of the evaporator; a first preheater switching valve and a vacuum preheater are provided between the inlet of the first preheater and the inlet of the evaporator; the first preheater switching valve and the vacuum preheater are arranged in parallel; a vacuum preheater switching valve is provided at the inlet of the vacuum preheater; a primary steam pipeline and a secondary steam pipeline are connected in parallel to the inlet of the evaporator; a primary steam valve is provided on the primary steam pipeline; the outlet of the evaporator is connected to a flash tank; the outlet of the flash tank is connected to the inlet of the compressor through a compressor inlet valve; the outlet of the compressor is connected to the inlet of the evaporator through a secondary steam pipeline; a compressor outlet valve is provided on the secondary steam pipeline; the liquid outlet of the flash tank is connected to the inlet of the evaporator through a reflux pipeline in sequence after passing through a circulation pump, a densitometer and a regulating valve; the outlet of the flash tank is connected to the vacuum preheater through a suction pipeline; a vacuum pump valve is provided on the suction pipeline.

2. The MVR double-loop evaporation concentration system according to claim 1, wherein A discharge pipeline is provided between the densitometer and the regulating valve; a discharge valve is provided on the discharge pipeline.

3. The MVR double-loop evaporation and concentration system according to claim 1, wherein The condensed water in the evaporator returns to the first preheater through a pipeline in sequence after passing through a condensate tank and a condensate pump.

4. The MVR double-loop evaporation concentration system according to claim 1, characterized in that, A vacuum pump is provided at the outlet of the vacuum preheater; the inlet of the vacuum preheater is connected to the suction pipeline.

5. The MVR double-loop evaporation concentration system according to claim 1, wherein The outlet of the vacuum preheater is connected to the reflux pipeline behind the regulating valve through a pipeline.

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