MVR (Mechanical Vapor Recompression) flexible evaporation system with large load regulation ratio and evaporation process

Abstract

The invention discloses an MVR (Mechanical Vapor Recompression) flexible evaporation system with a large load regulation ratio and an evaporation process, and belongs to the technical field of evaporation and concentration. The MVR flexible evaporation system comprises N stages of MVR subsystems, and N is greater than or equal to 2; each stage of MVR subsystem is provided with an independent feeding pipeline and an independent discharging pipeline; a series connection pipeline is connected between every two adjacent stages of MVR subsystems; a discharge pipeline of the Kth stage of MVR subsystem is connected to a raw material inlet of the (K + 1) th stage of MVR subsystem through a series connection pipeline; k = 1, 2,..., N-1. The MVR flexible evaporation process disclosed by the invention is carried out by adopting the system; and selecting series operation, parallel operation or independent operation according to the operation load. Aiming at evaporated materials with the boiling point rise being larger than or equal to 5 DEG C and different materials with the boiling point rise being similar to that of a single-stage steam compressor, the load adjusting problem existing in traditional MVR concentration operation can be effectively solved, the production efficiency is improved, the production cost is reduced, and wide application prospects and market values are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of evaporation and concentration, and in particular relates to an MVR flexible evaporation system with a large load regulation ratio and an evaporation process. Background Art

[0002] Mechanical Vapor Recompression (MVR) technology recovers the latent heat of secondary steam through a steam compressor, achieving thermal energy recycling. It boasts the advantages of high efficiency, energy saving, and environmental protection, and has been widely used in the chemical, pharmaceutical, and food industries. However, traditional MVR systems still have some key issues: (1) Limited load regulation capability: Due to the narrow load regulation range of centrifugal steam compressors, conventional MVR systems usually need to maintain a load of 70%-100%. This brings great difficulties to load regulation in actual production. Changes in the amount of raw materials, fluctuations in material concentration, and fluctuations in market demand often require the MVR device to operate at a load below 70%. To cope with low load demands, existing technologies usually adopt two passive compensation methods: one is to add cold steam or process water (water addition) to the system, and the other is to configure multiple parallel MVR concentration production lines and manually start and stop the spare production lines to balance the load. These practices not only greatly increase the complexity of operation, but more importantly, they directly lead to significant additional energy consumption (water addition requires additional heating and temperature increase, and frequent start and stop cause energy loss), which greatly weakens the energy-saving benefits of MVR technology.

[0003] (2) High equipment redundancy costs: The common practice of connecting multiple MVR production lines in parallel to address load adaptability issues leads to significant equipment redundancy. In particular, each parallel MVR system is typically equipped with a complete preheating system (such as a preheater). This not only takes up a large amount of site space, but also significantly increases the initial construction cost (CAPEX) of the entire device, thereby limiting the application and promotion of MVR technology in scenarios requiring flexible load adjustment.

[0004] Therefore, how to break through the problem of limited operating load range of centrifugal steam compressors in traditional MVR systems (only applicable to 70%-100%), so that it can effectively adapt to continuous low-load operation requirements (below 70%), and reduce equipment redundancy investment costs while avoiding energy waste, has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the Invention

[0005] One of the objectives of the present invention is to provide an MVR flexible evaporation system with a large load adjustment ratio, flexibly combining multiple MVR systems, solving the problem of limited load adjustment range of conventional MVR devices, and greatly improving the versatility and operability of the system.

[0006] A second object of the present invention is to provide an MVR flexible evaporation process with a large load adjustment ratio, which is carried out using the above system.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A first aspect of the present invention discloses an MVR flexible evaporation system with a large load turndown ratio, comprising N-stage MVR subsystems, where N ≥ 2; Each level of the MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; The discharge pipeline of the K-th level MVR subsystem is connected to the raw material inlet of the (K+1)-th level MVR subsystem through the series connection pipeline; K=1, 2, ..., N-1.

[0008] In some embodiments of the present invention, each stage of the MVR subsystem includes an evaporator and a vapor compressor; The feed pipeline is connected to the raw material inlet of the evaporator; the steam outlet of the evaporator is connected to the steam compressor, the outlet of the steam compressor is connected to the steam inlet of the evaporator, and the discharge pipeline is connected to the discharge port of the evaporator.

[0009] In some embodiments of the present invention, each stage of the MVR subsystem further includes a gas-liquid separator and a steam scrubber; the evaporator, gas-liquid separator, steam scrubber and steam compressor are connected in sequence.

[0010] In some embodiments of the present invention, each stage of the MVR subsystem further includes an evaporation circulation pump and a concentrated liquid circulation pipeline, wherein the evaporation circulation pump is arranged on the discharge pipeline, and the concentrated liquid circulation pipeline is connected to the discharge pipeline and connected to the evaporator raw material inlet.

[0011] In some embodiments of the present invention, each stage of the MVR subsystem further includes a steam scrubber material circulation line, and a steam scrubber circulation pump is provided on the circulation line.

[0012] In some embodiments of the present invention, the MVR flexible evaporation system with a large load turndown ratio further includes a raw material preheating subsystem, and the feed line of each stage of the MVR subsystem is connected to the output end of the raw material preheating subsystem.

[0013] In some embodiments of the present invention, the discharge pipeline of each stage of the MVR subsystem is connected to the raw material preheating subsystem for preheating the raw material and recovering heat.

[0014] In some embodiments of the present invention, each serially connected pipeline is provided with a valve.

[0015] In some embodiments of the present invention, valves are provided on the feed pipelines of the 2nd to Nth stage MVR subsystems.

[0016] The second aspect of the present invention discloses an MVR flexible evaporation process with a large load turndown ratio, which is carried out using the above-mentioned system; Preferably, the process is used for evaporating materials whose boiling point rise differs from the temperature rise of a single-stage steam compressor by 5°C or more, and for evaporating different materials with similar boiling point rises; Preferably, series operation, parallel operation or individual operation is selected according to the operating load.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes, for the first time, the flexible combination of two or more MVR systems (≥3 stages). Based on system load fluctuations, this system can flexibly switch between series and parallel operation (for high loads), partial parallel operation, or independent operation (for low loads), effectively addressing the limited load adjustment range of conventional MVR systems. The system's operating load range is expanded from the traditional 70%-100% to 25%-100%.

[0018] Each stage of the MVR system in this invention is capable of operating independently and producing product. For evaporating materials whose boiling point rise differs by 5°C or more from the temperature rise of a single-stage steam compressor (such as lithium chloride solution, sodium chloride solution, potassium bicarbonate solution, and potassium carbonate solution), this invention innovatively proposes that under low operating load conditions, a single-stage MVR system can operate independently and achieve product output. Under high load conditions, the various MVR systems can be combined and operated in series or parallel, allowing for flexible adjustment of the evaporation depth based on process requirements and market demand, significantly enhancing the adjustable range and flexibility of the device's operating load.

[0019] For example, in a three-stage MVR system, the single-stage MVR can operate at a minimum load of 25% of the total unit load. In a two-stage MVR system, the single-stage MVR can operate at a minimum load of 35% of the total unit load. By operating two or three-stage MVR systems in series, parallel, or independently, stable operation can be achieved across a wide load range without diluting the raw materials, significantly improving the energy efficiency of the evaporation and concentration process and achieving high efficiency and energy conservation.

[0020] The present invention adopts an integrated shared raw material preheating system. All MVR subsystems share a single raw material preheating system, avoiding the increased investment associated with multiple traditional MVR systems with independent raw material preheating systems. This provides a more cost-effective solution and simplifies the operation of the device.

[0021] In the present invention, all discharged materials first enter the raw material preheating system, and through optimized combination, the maximum recovery and utilization of heat is achieved.

[0022] The flexible system design of the present invention can flexibly adjust the evaporation depth to adapt to different process requirements; at the same time, it is also suitable for the evaporation of different materials with similar boiling points, achieving the goal of "flexible device" and greatly improving the versatility and operability of the system.

[0023] In summary, the MVR flexible evaporation system with a large load regulation ratio proposed in the present invention can effectively solve the load regulation problem existing in traditional MVR concentration operations for evaporated materials whose boiling point rise differs from the temperature rise of a single-stage steam compressor by more than 5°C, thereby improving production efficiency and reducing production costs. It has broad application prospects and market value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Attachment Figure 1 It is a structural schematic diagram of the present invention.

[0025] The names corresponding to the reference numerals are: 11 / 21 / 31-evaporator, 12 / 22 / 32-gas-liquid separator, 13 / 23 / 33-steam washing tower, 14 / 24 / 34-steam compressor, 15 / 25 / 35-steam washing tower circulation pump, 16 / 26 / 36-evaporation circulation pump; 100-Raw material preheating subsystem; 101 / 201 / 301-feed pipeline, 102 / 202 / 302-discharge pipeline, 103 / 203-series connection pipeline, 104 / 204 / 304-concentrate circulation pipeline, 105 / 205 / 305-steam washing tower material circulation line. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load turndown ratio, including a three-stage MVR subsystem; Each level of the MVR subsystem has an independent feed pipeline and a discharge pipeline. The first level MVR subsystem has a feed pipeline 101 and a discharge pipeline 102; the second level MVR subsystem has a feed pipeline 201 and a discharge pipeline 202; and the third level MVR subsystem has a feed pipeline 301 and a discharge pipeline 302. A series connection pipeline is connected between two adjacent MVR subsystems; the discharge pipeline 102 of the first-stage MVR subsystem is connected to the raw material inlet of the second-stage MVR subsystem through the series connection pipeline 103; the discharge pipeline 202 of the second-stage MVR subsystem is connected to the raw material inlet of the third-stage MVR subsystem through the series connection pipeline 203.

[0028] Example 2 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load turndown ratio, including a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; Each level of the MVR subsystem includes an evaporator and a steam compressor; the feed pipeline is connected to the raw material inlet of the evaporator; the steam outlet of the evaporator is connected to the steam compressor, the outlet of the steam compressor is connected to the steam inlet of the evaporator, and the discharge pipeline is connected to the discharge port of the evaporator. Specifically: The feed pipeline 101 of the first-stage MVR subsystem is connected to the raw material inlet of the evaporator 11, and the steam outlet of the evaporator 11 is connected to the steam compressor 14 via a pipeline; the outlet of the steam compressor 14 is connected to the steam inlet of the evaporator 11; the discharge pipeline 102 is connected from the discharge port of the evaporator 11; the discharge pipeline 102 is connected to the raw material inlet of the evaporator 21 of the second-stage MVR subsystem through the series connection pipeline 103.

[0029] The feed pipeline 201 of the second-stage MVR subsystem is connected to the raw material inlet of the evaporator 21, and the steam outlet of the evaporator 21 is connected to the steam compressor 24 via a pipeline; the outlet of the steam compressor 24 is connected to the steam inlet of the evaporator 21; the discharge pipeline 202 is connected from the discharge port of the evaporator 21; the discharge pipeline 202 is connected to the raw material inlet of the evaporator 31 of the third-stage MVR subsystem through the series connection pipeline 203.

[0030] The feed pipeline 301 of the third-stage MVR subsystem is connected to the raw material inlet of the evaporator 31, and the steam outlet of the evaporator 31 is connected to the steam compressor 34 via a pipeline; the outlet of the steam compressor 34 is connected to the steam inlet of the evaporator 31; and the discharge pipeline 302 is connected to the discharge port of the evaporator 31.

[0031] This second embodiment provides a more preferred technical solution based on the first embodiment. Specifically, each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline is connected to the raw material inlet of the evaporator; the steam outlet of the evaporator is connected to the steam compressor, and the outlet of the steam compressor is connected to the steam inlet of the evaporator. The discharge pipeline is connected to the discharge port of the evaporator. The mechanical supercharging of the steam compressor achieves closed-loop reuse of secondary steam, enabling the evaporation system to achieve a highly efficient self-heating cycle and significantly reducing fresh steam consumption. Example 3 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load turndown ratio, including a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor; the feed pipeline is connected to the raw material inlet of the evaporator; the steam outlet of the evaporator is connected to the steam compressor, and the outlet of the steam compressor is connected to the steam inlet of the evaporator. The discharge pipeline is connected to the discharge port of the evaporator. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber; the evaporator, gas-liquid separator, steam scrubber and steam compressor are connected in sequence. Specifically: The feed pipeline 101 of the first-stage MVR subsystem is connected to the raw material inlet of the evaporator 11, and the steam outlet of the evaporator 11 is connected to the gas-liquid separator 12 via a pipeline. The gas outlet of the gas-liquid separator 12 is connected to the gas inlet of the steam scrubber 13, and the gas outlet of the steam scrubber 13 is connected to the steam compressor 14; the outlet of the steam compressor 14 is connected to the steam inlet of the evaporator 11; the discharge pipeline 102 is connected to the discharge port of the evaporator 11; the discharge pipeline 102 is connected to the raw material inlet of the evaporator 21 of the second-stage MVR subsystem through the series connection pipeline 103.

[0032] The feed pipeline 201 of the second-stage MVR subsystem is connected to the raw material inlet of the evaporator 21, and the steam outlet of the evaporator 21 is connected to the gas-liquid separator 22 via a pipeline. The gas outlet of the gas-liquid separator 22 is connected to the gas inlet of the steam scrubber 23, and the gas outlet of the steam scrubber 23 is connected to the steam compressor 24; the outlet of the steam compressor 24 is connected to the steam inlet of the evaporator 21; the discharge pipeline 202 is connected to the discharge port of the evaporator 21; the discharge pipeline 202 is connected to the raw material inlet of the evaporator 31 of the third-stage MVR subsystem through the series connection pipeline 203.

[0033] The feed pipeline 301 of the third-stage MVR subsystem is connected to the raw material inlet of the evaporator 31, and the steam outlet of the evaporator 31 is connected to the gas-liquid separator 32 via a pipeline. The gas outlet of the gas-liquid separator 32 is connected to the gas inlet of the steam scrubber 33, and the gas outlet of the steam scrubber 33 is connected to the steam compressor 34; the outlet of the steam compressor 34 is connected to the steam inlet of the evaporator 31; the discharge pipeline 302 is connected to the discharge port of the evaporator 31.

[0034] This Example 3 provides a more preferred technical solution based on Example 2. Specifically, each stage of the MVR subsystem is defined to include a gas-liquid separator and a steam scrubber; the evaporator, gas-liquid separator, steam scrubber, and steam compressor are sequentially connected. The gas-liquid separator and steam scrubber purify the secondary steam step by step, ensuring the quality of steam entering the compressor, preventing impurities from corroding equipment, and maintaining stable system energy efficiency.

[0035] Example 4 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load turndown ratio, including a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline connects to the evaporator's raw material inlet; the evaporator's steam outlet connects to the steam compressor, and the steam compressor outlet connects to the evaporator's steam inlet. The discharge pipeline is connected to the evaporator's discharge port. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber. The evaporator, gas-liquid separator, steam scrubber, and steam compressor are connected in sequence.

[0036] Each level of MVR subsystem also includes an evaporation circulation pump and a concentrated liquid circulation pipeline, wherein the evaporation circulation pump is arranged on the discharge pipeline, and the concentrated liquid circulation pipeline is connected to the discharge pipeline and connected to the evaporator raw material inlet.

[0037] Specifically: The first-stage MVR subsystem's feed line 101 connects to the raw material inlet of evaporator 11. The vapor outlet of evaporator 11 is connected to gas-liquid separator 12 via a pipeline. The vapor outlet of gas-liquid separator 12 is connected to the gas inlet of steam scrubber 13, which in turn is connected to steam compressor 14. The outlet of steam compressor 14 connects to the steam inlet of evaporator 11. A discharge line 102 extends from the discharge port of evaporator 11 and is connected to the raw material inlet of evaporator 21 of the second-stage MVR subsystem via a series connection line 103. The first-stage MVR subsystem also includes an evaporation circulation pump 16 and a concentrate circulation line 104. The evaporation circulation pump 16 is mounted on discharge line 102, which in turn connects to the raw material inlet of evaporator 11.

[0038] The second-stage MVR subsystem's feed line 201 connects to the feed inlet of evaporator 21. The vapor outlet of evaporator 21 is connected to a gas-liquid separator 22 via a pipeline. The vapor outlet of gas-liquid separator 22 is connected to the gas inlet of steam scrubber 23, which in turn is connected to steam compressor 24. The outlet of steam compressor 24 connects to the steam inlet of evaporator 21. A discharge line 202 extends from the discharge port of evaporator 21 and is connected to the feed inlet of evaporator 31 of the third-stage MVR subsystem via a series connection line 203. The second-stage MVR subsystem also includes an evaporation circulation pump 26 and a concentrate circulation line 204. The evaporation circulation pump 26 is mounted on the discharge line 202, which in turn connects to the feed inlet of evaporator 21.

[0039] The third-stage MVR subsystem's feed line 301 connects to the raw material inlet of evaporator 31. The vapor outlet of evaporator 31 is connected to a gas-liquid separator 32 via a pipeline. The vapor outlet of gas-liquid separator 32 is connected to the gas inlet of steam scrubber 33, which in turn is connected to steam compressor 34. The outlet of steam compressor 34 connects to the steam inlet of evaporator 31. A discharge line 302 connects to the discharge port of evaporator 31. The third-stage MVR subsystem also includes an evaporation circulation pump 36 and a concentrate circulation line 304. The evaporation circulation pump 36 is installed on the discharge line 302, which connects to the raw material inlet of evaporator 31.

[0040] This fourth embodiment provides a more preferred technical solution based on the third embodiment. Specifically, each MVR subsystem also includes an evaporation circulation pump and a concentrate circulation pipeline. The evaporation circulation pump is installed on the discharge pipeline, and the concentrate circulation pipeline is connected from the discharge pipeline to the evaporator feed inlet. The forced circulation pump and concentrate reflux form a double closed-loop flow, enhancing heat transfer efficiency and precisely controlling the concentrate concentration.

[0041] Example 5 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load turndown ratio, including a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline connects to the evaporator's raw material inlet; the evaporator's steam outlet connects to the steam compressor, and the steam compressor outlet connects to the evaporator's steam inlet. The discharge pipeline is connected to the evaporator's discharge port. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber. The evaporator, gas-liquid separator, steam scrubber, and steam compressor are connected in sequence.

[0042] Each MVR subsystem also includes an evaporation circulation pump and a concentrate circulation pipeline. The evaporation circulation pump is installed on the discharge pipeline, and the concentrate circulation pipeline is connected from the discharge pipeline to the evaporator feed inlet. Each MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump.

[0043] Specifically: The first-stage MVR subsystem's feed line 101 connects to the raw material inlet of evaporator 11. The vapor outlet of evaporator 11 is connected to gas-liquid separator 12 via a pipeline. The vapor outlet of gas-liquid separator 12 is connected to the gas inlet of steam scrubber 13, which in turn is connected to steam compressor 14. The outlet of steam compressor 14 connects to the steam inlet of evaporator 11. A discharge line 102 extends from the discharge port of evaporator 11 and is connected to the raw material inlet of evaporator 21 of the second-stage MVR subsystem via a series connection line 103. The first-stage MVR subsystem also includes an evaporation circulation pump 16 and a concentrate circulation line 104. The evaporation circulation pump 16 is mounted on discharge line 102, which in turn connects to the raw material inlet of evaporator 11. The first-stage MVR subsystem further includes a steam scrubber material circulation line 105 , on which a steam scrubber circulation pump 15 is provided.

[0044] The second-stage MVR subsystem's feed line 201 connects to the feed inlet of evaporator 21. The vapor outlet of evaporator 21 is connected to a gas-liquid separator 22 via a pipeline. The vapor outlet of gas-liquid separator 22 is connected to the gas inlet of steam scrubber 23, which in turn is connected to steam compressor 24. The outlet of steam compressor 24 connects to the steam inlet of evaporator 21. A discharge line 202 extends from the discharge port of evaporator 21 and is connected to the feed inlet of evaporator 31 of the third-stage MVR subsystem via a series connection line 203. The second-stage MVR subsystem also includes an evaporation circulation pump 26 and a concentrate circulation line 204. The evaporation circulation pump 26 is mounted on the discharge line 202, which in turn connects to the feed inlet of evaporator 21. The second-stage MVR subsystem further includes a steam scrubber material circulation line 205 , on which a steam scrubber circulation pump 25 is provided.

[0045] The third-stage MVR subsystem's feed line 301 connects to the raw material inlet of evaporator 31. The vapor outlet of evaporator 31 is connected to gas-liquid separator 32 via a pipeline. The vapor outlet of gas-liquid separator 32 is connected to the gas inlet of steam scrubber 33, which in turn is connected to steam compressor 34. The outlet of steam compressor 34 connects to the steam inlet of evaporator 31. A discharge line 302 connects to the discharge port of evaporator 31. The third-stage MVR subsystem also includes an evaporation circulation pump 36 and a concentrate circulation line 304. The evaporation circulation pump 36 is located on discharge line 302, which connects to the raw material inlet of evaporator 31. The third-stage MVR subsystem also includes a steam scrubber material circulation line 305, which is equipped with a steam scrubber circulation pump 35.

[0046] This embodiment 5 provides a more preferred technical solution based on embodiment 4. Specifically, each stage of the MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump. The forced circulation ensures the scrubbing effect and system stability. Example 6 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load adjustment ratio, including a raw material preheating subsystem 100 and a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; the feed pipeline of each level of MVR subsystem is connected to the output end of the raw material preheating subsystem.

[0047] A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline connects to the evaporator's raw material inlet; the evaporator's steam outlet connects to the steam compressor, and the steam compressor outlet connects to the evaporator's steam inlet. The discharge pipeline is connected to the evaporator's discharge port. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber. The evaporator, gas-liquid separator, steam scrubber, and steam compressor are connected in sequence.

[0048] Each MVR subsystem also includes an evaporation circulation pump and a concentrate circulation pipeline. The evaporation circulation pump is installed on the discharge pipeline, and the concentrate circulation pipeline is connected from the discharge pipeline to the evaporator feed inlet. Each MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump.

[0049] Specifically: The input end of the raw material preheating subsystem 100 is connected to a raw material solution delivery pipeline, and the output end is connected to three independent feed pipelines 101, 201, and 301 respectively.

[0050] The first-stage MVR subsystem's feed line 101 connects to the raw material inlet of evaporator 11. The vapor outlet of evaporator 11 is connected to gas-liquid separator 12 via a pipeline. The vapor outlet of gas-liquid separator 12 is connected to the gas inlet of steam scrubber 13, which in turn is connected to steam compressor 14. The outlet of steam compressor 14 connects to the steam inlet of evaporator 11. A discharge line 102 extends from the discharge port of evaporator 11 and is connected to the raw material inlet of evaporator 21 of the second-stage MVR subsystem via a series connection line 103. The first-stage MVR subsystem also includes an evaporation circulation pump 16 and a concentrate circulation line 104. The evaporation circulation pump 16 is mounted on discharge line 102, which in turn connects to the raw material inlet of evaporator 11. The first-stage MVR subsystem further includes a steam scrubber material circulation line 105 , on which a steam scrubber circulation pump 15 is provided.

[0051] The second-stage MVR subsystem's feed line 201 connects to the feed inlet of evaporator 21. The vapor outlet of evaporator 21 is connected to a gas-liquid separator 22 via a pipeline. The vapor outlet of gas-liquid separator 22 is connected to the gas inlet of steam scrubber 23, which in turn is connected to steam compressor 24. The outlet of steam compressor 24 connects to the steam inlet of evaporator 21. A discharge line 202 extends from the discharge port of evaporator 21 and is connected to the feed inlet of evaporator 31 of the third-stage MVR subsystem via a series connection line 203. The second-stage MVR subsystem also includes an evaporation circulation pump 26 and a concentrate circulation line 204. The evaporation circulation pump 26 is mounted on the discharge line 202, which in turn connects to the feed inlet of evaporator 21. The second-stage MVR subsystem further includes a steam scrubber material circulation line 205 , on which a steam scrubber circulation pump 25 is provided.

[0052] The third-stage MVR subsystem's feed line 301 connects to the raw material inlet of evaporator 31. The vapor outlet of evaporator 31 is connected to gas-liquid separator 32 via a pipeline. The vapor outlet of gas-liquid separator 32 is connected to the gas inlet of steam scrubber 33, which in turn is connected to steam compressor 34. The outlet of steam compressor 34 connects to the steam inlet of evaporator 31. A discharge line 302 connects to the discharge port of evaporator 31. The third-stage MVR subsystem also includes an evaporation circulation pump 36 and a concentrate circulation line 304. The evaporation circulation pump 36 is located on discharge line 302, which connects to the raw material inlet of evaporator 31. The third-stage MVR subsystem also includes a steam scrubber material circulation line 305, which is equipped with a steam scrubber circulation pump 35.

[0053] This Example 6 provides a more preferred technical solution based on Example 5. Specifically, the MVR flexible evaporation system also includes a raw material preheating subsystem, with the feed pipeline of each MVR subsystem connected to the output of the raw material preheating subsystem. All MVR subsystems are integrated and share a single raw material preheating system, avoiding the increased investment associated with traditional multiple MVR systems equipped with independent raw material preheating systems. This provides a more cost-effective solution and simplifies the operation of the device.

[0054] Example 7 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load adjustment ratio, including a raw material preheating subsystem 100 and a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; the feed pipeline of each level of MVR subsystem is connected to the output end of the raw material preheating subsystem.

[0055] A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline connects to the evaporator's raw material inlet; the evaporator's steam outlet connects to the steam compressor, and the steam compressor outlet connects to the evaporator's steam inlet. The discharge pipeline is connected to the evaporator's discharge port. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber. The evaporator, gas-liquid separator, steam scrubber, and steam compressor are connected in sequence.

[0056] Each MVR subsystem also includes an evaporation circulation pump and a concentrate circulation pipeline. The evaporation circulation pump is installed on the discharge pipeline, and the concentrate circulation pipeline is connected from the discharge pipeline to the evaporator feed inlet. Each MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump.

[0057] The discharge pipeline of each level of MVR subsystem is connected to the raw material preheating subsystem 100 for preheating the raw materials and recovering heat; the raw material preheating subsystem 100 is connected to a concentrated liquid product delivery line.

[0058] Specifically: The input end of the raw material preheating subsystem 100 is connected to a raw material solution delivery pipeline, and the output end is connected to three independent feed pipelines 101, 201, and 301 respectively.

[0059] The first-stage MVR subsystem's feed line 101 connects to the raw material inlet of evaporator 11. The vapor outlet of evaporator 11 is connected to gas-liquid separator 12 via a pipeline. The vapor outlet of gas-liquid separator 12 is connected to the gas inlet of steam scrubber 13, which in turn is connected to steam compressor 14. The outlet of steam compressor 14 connects to the steam inlet of evaporator 11. A discharge line 102 extends from the discharge port of evaporator 11 and is connected to the raw material inlet of evaporator 21 of the second-stage MVR subsystem via a series connection line 103. The first-stage MVR subsystem also includes an evaporation circulation pump 16 and a concentrate circulation line 104. The evaporation circulation pump 16 is mounted on discharge line 102, which in turn connects to the raw material inlet of evaporator 11. The first-stage MVR subsystem also includes a steam scrubber material circulation line 105, which is provided with a steam scrubber circulation pump 15. The discharge line 102 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0060] The second-stage MVR subsystem's feed line 201 connects to the feed inlet of evaporator 21. The vapor outlet of evaporator 21 is connected to a gas-liquid separator 22 via a pipeline. The vapor outlet of gas-liquid separator 22 is connected to the gas inlet of steam scrubber 23, which in turn is connected to steam compressor 24. The outlet of steam compressor 24 connects to the steam inlet of evaporator 21. A discharge line 202 extends from the discharge port of evaporator 21 and is connected to the feed inlet of evaporator 31 of the third-stage MVR subsystem via a series connection line 203. The second-stage MVR subsystem also includes an evaporation circulation pump 26 and a concentrate circulation line 204. The evaporation circulation pump 26 is mounted on the discharge line 202, which in turn connects to the feed inlet of evaporator 21. The second-stage MVR subsystem also includes a steam scrubber material circulation line 205, which is provided with a steam scrubber circulation pump 25. The discharge line 202 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0061] The third-stage MVR subsystem's feed line 301 connects to the raw material inlet of evaporator 31. The vapor outlet of evaporator 31 is connected to gas-liquid separator 32 via a pipeline. The vapor outlet of gas-liquid separator 32 is connected to the gas inlet of steam scrubber 33, which in turn is connected to steam compressor 34. The outlet of steam compressor 34 connects to the steam inlet of evaporator 31. A discharge line 302 connects to the discharge port of evaporator 31. The third-stage MVR subsystem also includes an evaporation circulation pump 36 and a concentrate circulation line 304. The evaporation circulation pump 36 is located on discharge line 302, which connects to the raw material inlet of evaporator 31. The third-stage MVR subsystem also includes a steam scrubber material circulation line 305, which is equipped with a steam scrubber circulation pump 35. The discharge pipeline 102 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0062] This Example 7 provides a more preferred technical solution based on Example 6. Specifically, the discharge pipeline of each MVR subsystem is connected to the raw material preheating subsystem for preheating the raw materials and recovering heat. All discharges first enter the raw material preheating system, and through optimized combination, maximum heat recovery is achieved.

[0063] Example 8 As attached Figure 1 As shown, this embodiment discloses an MVR flexible evaporation system with a large load adjustment ratio, including a raw material preheating subsystem 100 and a three-stage MVR subsystem; Each level of MVR subsystem has independent feed and discharge pipelines; the feed pipeline of each level of MVR subsystem is connected to the output end of the raw material preheating subsystem.

[0064] A series connection pipeline is connected between two adjacent MVR subsystems; Each stage of the MVR subsystem includes an evaporator and a steam compressor. The feed pipeline connects to the evaporator's raw material inlet; the evaporator's steam outlet connects to the steam compressor, and the steam compressor outlet connects to the evaporator's steam inlet. The discharge pipeline is connected to the evaporator's discharge port. Each stage of the MVR subsystem also includes a gas-liquid separator and a steam scrubber. The evaporator, gas-liquid separator, steam scrubber, and steam compressor are connected in sequence.

[0065] Each MVR subsystem also includes an evaporation circulation pump and a concentrate circulation pipeline. The evaporation circulation pump is installed on the discharge pipeline, and the concentrate circulation pipeline is connected from the discharge pipeline to the evaporator feed inlet. Each MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump.

[0066] The discharge pipeline of each level of MVR subsystem is connected to the raw material preheating subsystem 100 for preheating the raw materials and recovering heat; the raw material preheating subsystem 100 is connected to a concentrated liquid product delivery line.

[0067] Each serially connected pipeline is provided with a valve; the feed pipelines of the 2nd to Nth stage MVR subsystems are provided with a valve. In this embodiment, N=3.

[0068] Specifically: The input end of the raw material preheating subsystem 100 is connected to a raw material solution delivery pipeline, and the output end is connected to three independent feed pipelines 101, 201, and 301 respectively.

[0069] The first-stage MVR subsystem's feed line 101 connects to the raw material inlet of evaporator 11. The vapor outlet of evaporator 11 is connected to gas-liquid separator 12 via a pipeline. The vapor outlet of gas-liquid separator 12 is connected to the gas inlet of steam scrubber 13, which in turn is connected to steam compressor 14. The outlet of steam compressor 14 connects to the steam inlet of evaporator 11. A discharge line 102 extends from the discharge port of evaporator 11 and is connected to the raw material inlet of evaporator 21 of the second-stage MVR subsystem via a series connection line 103. The first-stage MVR subsystem also includes an evaporation circulation pump 16 and a concentrate circulation line 104. The evaporation circulation pump 16 is mounted on discharge line 102, which in turn connects to the raw material inlet of evaporator 11. The first-stage MVR subsystem also includes a steam scrubber material circulation line 105, which is provided with a steam scrubber circulation pump 15. The discharge line 102 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0070] The second-stage MVR subsystem's feed line 201 connects to the feed inlet of evaporator 21. The vapor outlet of evaporator 21 is connected to a gas-liquid separator 22 via a pipeline. The vapor outlet of gas-liquid separator 22 is connected to the gas inlet of steam scrubber 23, which in turn is connected to steam compressor 24. The outlet of steam compressor 24 connects to the steam inlet of evaporator 21. A discharge line 202 extends from the discharge port of evaporator 21 and is connected to the feed inlet of evaporator 31 of the third-stage MVR subsystem via a series connection line 203. The second-stage MVR subsystem also includes an evaporation circulation pump 26 and a concentrate circulation line 204. The evaporation circulation pump 26 is mounted on the discharge line 202, which in turn connects to the feed inlet of evaporator 21. The second-stage MVR subsystem also includes a steam scrubber material circulation line 205, which is provided with a steam scrubber circulation pump 25. The discharge line 202 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0071] The third-stage MVR subsystem's feed line 301 connects to the raw material inlet of evaporator 31. The vapor outlet of evaporator 31 is connected to gas-liquid separator 32 via a pipeline. The vapor outlet of gas-liquid separator 32 is connected to the gas inlet of steam scrubber 33, which in turn is connected to steam compressor 34. The outlet of steam compressor 34 connects to the steam inlet of evaporator 31. A discharge line 302 connects to the discharge port of evaporator 31. The third-stage MVR subsystem also includes an evaporation circulation pump 36 and a concentrate circulation line 304. The evaporation circulation pump 36 is located on discharge line 302, which connects to the raw material inlet of evaporator 31. The third-stage MVR subsystem also includes a steam scrubber material circulation line 305, which is equipped with a steam scrubber circulation pump 35. The discharge pipeline 102 is connected to the raw material preheating subsystem 100 for preheating the raw material solution.

[0072] Valves are provided on the serial connection pipelines 103 and 203; valves are provided on the feed pipelines 201 and 203 of the 2nd and 3rd stage MVR subsystems.

[0073] This eighth embodiment provides a more preferred technical solution based on the seventh embodiment. Specifically, valves are installed on each serially connected pipeline; valves are installed on the feed pipelines of the second through Nth stage MVR subsystems. These valves enable flexible switching of multi-stage system operating conditions, precisely controlling flow balance and process parameters at each stage, ensuring the system's adaptability to complex operating conditions and enhancing operational flexibility. Example 9 This embodiment discloses the MVR flexible evaporation process with a large load adjustment ratio of the present invention, which is carried out using the system described in embodiment 8 of claim 1.

[0074] According to the operating load, select series operation, parallel operation or single operation.

[0075] 1. Serial operation The raw material is preheated to the evaporation temperature in the preheating system and then enters the primary MVR evaporation system for water evaporation. The evaporated secondary steam is compressed and heated by the steam compressor and then returned to the primary MVR evaporation system for recycling. The liquid exiting the primary MVR evaporation system enters the secondary MVR evaporation system for further water evaporation. The evaporated secondary steam is compressed and heated by the steam compressor and then returned to the secondary MVR evaporation system for recycling. The liquid exiting the secondary MVR evaporation system enters the tertiary MVR evaporation system for further water evaporation. The evaporated secondary steam is compressed and heated by the steam compressor and then returned to the tertiary MVR evaporation system for recycling. The liquid is finally discharged from the tertiary MVR system.

[0076] 2. Parallel operation or independent operation The raw materials are preheated to the evaporation temperature through the preheating system and then enter any one of the MVR evaporation systems, or are divided into several streams and enter each level of MVR evaporation system to evaporate water. The evaporated secondary steam is compressed and heated by the steam compressors at each level and then returns to the MVR evaporation system of that level for recycling. Each level of MVR system can discharge materials separately.

[0077] The above is only a preferred embodiment of the invention and does not impose any formal limitation on the invention. Based on the technical essence of the invention and within the spirit and principles of the invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the invention.

Claims

1. A MVR flexible evaporation system with a large load turndown ratio, characterized in that: Includes N-level MVR subsystems, where N ≥ 2; Each level of the MVR subsystem has independent feed and discharge pipelines; A series connection pipeline is connected between two adjacent MVR subsystems; The discharge pipeline of the K-th level MVR subsystem is connected to the raw material inlet of the (K+1)-th level MVR subsystem through the series connection pipeline; K=1, 2, ..., N-1.

2. The MVR flexible evaporation system with a large load turndown ratio according to claim 1, characterized in that: Each stage of the MVR subsystem includes an evaporator and a steam compressor; The feed pipeline is connected to the raw material inlet of the evaporator; the steam outlet of the evaporator is connected to the steam compressor, the outlet of the steam compressor is connected to the steam inlet of the evaporator, and the discharge pipeline is connected to the discharge port of the evaporator.

3. The MVR flexible evaporation system with a large load turndown ratio according to claim 2, characterized in that: Each level of the MVR subsystem also includes a gas-liquid separator and a steam scrubber; the evaporator, gas-liquid separator, steam scrubber and steam compressor are connected in sequence.

4. The MVR flexible evaporation system with a large load turndown ratio according to claim 2, characterized in that: Each level of MVR subsystem also includes an evaporation circulation pump and a concentrated liquid circulation pipeline, wherein the evaporation circulation pump is arranged on the discharge pipeline, and the concentrated liquid circulation pipeline is connected to the discharge pipeline and connected to the evaporator raw material inlet.

5. The MVR flexible evaporation system with a large load turndown ratio according to claim 2, characterized in that: Each stage of the MVR subsystem also includes a steam scrubber material circulation line, which is equipped with a steam scrubber circulation pump.

6. The MVR flexible evaporation system with a large load turndown ratio according to any one of claims 1 to 5, characterized in that: It also includes a raw material preheating subsystem, and the feed pipeline of each level of the MVR subsystem is connected to the output end of the raw material preheating subsystem.

7. The MVR flexible evaporation system with a large load turndown ratio according to claim 6, characterized in that: The discharge pipeline of each level of MVR subsystem is connected to the raw material preheating subsystem for preheating the raw materials and recovering heat.

8. The MVR flexible evaporation system with a large load turndown ratio according to any one of claims 1 to 5, characterized in that: Each serially connected pipeline is provided with a valve.

9. The MVR flexible evaporation system with a large load turndown ratio according to any one of claims 1 to 5, characterized in that: Valves are installed on the feed pipelines of the 2nd to Nth-level MVR subsystems.

10. A MVR flexible evaporation process with a large load adjustment ratio, characterized in that: The method is carried out using the system according to any one of claims 1 to 10; Preferably, the process is used for evaporating materials whose boiling point rise differs from the temperature rise of a single-stage steam compressor by 5°C or more, and for evaporating different materials with similar boiling point rises; Preferably, series operation, parallel operation or individual operation is selected according to the operating load.

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