阅读说明：本技术 一种大幅度调整蒸发产量范围的mvr系统及其工艺方法 (MVR system capable of greatly adjusting evaporation yield range and technological method thereof ) 是由 杨春光 庞劲风 赵利 吕海波 王艇 于轶 周启宏 马路 王永恒 毕扬 于 2019-10-08 设计创作，主要内容包括：本发明属于MVR装置技术领域,具体涉及一种大幅度调整蒸发产量范围的MVR系统及其工艺方法,该系统包括预热器、蒸汽压缩机、至少二个串联的单效蒸发器、多个汽液分离器,在第一、二的两个单效蒸发器之间的蒸汽输送管路上设切换阀I；在第一个汽液分离器的蒸汽出口和切换阀I间的管路上增设分支管路II,分支管路II与蒸汽压缩机的蒸汽入口的管路相连通,分支管路II上设切换阀II；在第二个单效蒸发器蒸汽入口和切换阀I之间的管路上设分支管路III,分支管路III与蒸汽压缩机蒸汽出口的管路相连通,分支管路III上设置切换阀III。本申请所述的MVR系统能够有效的实现在产能显著下降的工况下,仍可以稳定运行的技术效果。(The invention belongs to the technical field of MVR devices, and particularly relates to an MVR system capable of greatly adjusting the evaporation yield range and a process method thereof, wherein the system comprises a preheater, a vapor compressor, at least two single-effect evaporators connected in series and a plurality of vapor-liquid separators, wherein a switching valve I is arranged on a vapor conveying pipeline between the first single-effect evaporator and the second single-effect evaporator; a branch pipeline II is additionally arranged on a pipeline between a steam outlet of the first steam-liquid separator and the switching valve I, the branch pipeline II is communicated with a pipeline of a steam inlet of the steam compressor, and the switching valve II is arranged on the branch pipeline II; and a branch pipeline III is arranged on a pipeline between the steam inlet of the second single-effect evaporator and the switching valve I, the branch pipeline III is communicated with a pipeline of a steam outlet of the steam compressor, and the switching valve III is arranged on the branch pipeline III. The MVR system can effectively achieve the technical effect that the MVR system can still stably run under the working condition that the productivity is remarkably reduced.)

1. an MVR system for substantially adjusting the range of evaporation output, the system comprising a preheater, and at least 2 single effect evaporators connected in series, and a vapor-liquid separator cooperating with each single effect evaporator, respectively, and a vapor compressor providing vapor circulation for the system, each single effect evaporator having a vapor inlet, each vapor-liquid separator having a vapor outlet, the vapor compressor having a vapor inlet and a vapor outlet, the MVR system characterized in that: a switching valve I is arranged on a steam conveying pipeline between the first steam-liquid separator and the second single-effect evaporator; a branch pipeline II is additionally arranged on a pipeline between the steam outlet of the first steam-liquid separator and the switching valve I, the other end of the branch pipeline II is communicated with a pipeline of a steam inlet of the steam compressor, and the switching valve II is arranged on the branch pipeline II; and a branch pipeline III is additionally arranged on a pipeline between the steam inlet of the second single-effect evaporator and the switching valve I, the other end of the branch pipeline III is communicated with a pipeline of the steam outlet of the steam compressor, and the switching valve III is arranged on the branch pipeline III.

2. the MVR system of claim 1, wherein: when the switching valve I is opened and the switching valve II and the switching valve III are closed, the first single-effect evaporator and the second single-effect evaporator are in a series connection mode, a steam inlet of the first single-effect evaporator is communicated with a steam outlet of the steam compressor, and a steam outlet of the second steam-liquid separator is communicated with a steam inlet of the steam compressor; when the switching valve I is closed and the switching valve II and the switching valve III are opened, the first single-effect evaporator and the second single-effect evaporator are in a parallel mode, the steam outlets of the first vapor-liquid separator and the second vapor-liquid separator are respectively communicated with the steam inlet of the vapor compressor, and the steam inlets of the first single-effect evaporator and the second single-effect evaporator are respectively communicated with the steam outlet of the vapor compressor.

3. the MVR system of claim 1, wherein the vapor compressor is a high-speed centrifugal compressor.

4. The MVR system of claim 1, wherein the single effect evaporator is a falling film evaporator.

5. the MVR system of claim 1, wherein when the number of single-effect evaporators is 2:

(1) A switching valve I is arranged on a pipeline between a steam outlet of the first steam-liquid separator and a steam inlet of the second single-effect evaporator;

(2) a branch pipeline II is additionally arranged on a pipeline between the steam outlet of the first steam-liquid separator and the switching valve I, the other end of the branch pipeline II is communicated with a pipeline of a steam inlet of the steam compressor, and the switching valve II is arranged on the branch pipeline II;

(3) A branch pipeline III is additionally arranged on a pipeline between a steam inlet of the second single-effect evaporator and the switching valve I, the other end of the branch pipeline III is communicated with a pipeline of a steam outlet of the steam compressor, and the switching valve III is arranged on the branch pipeline III.

6. a process method for greatly adjusting the evaporation yield range of an MVR device is characterized in that: the MVR system of claim 1 is utilized to realize the interconversion of single-effect evaporation and multi-effect evaporation by controlling the opening and closing of the switching valve I, the switching valve II and the switching valve III.

7. The process of claim 6, wherein: the opening and closing modes of the control switching valve I, the switching valve II and the switching valve III are as follows: when the switching valve I is opened, the switching valve II and the switching valve III11 are closed, and multi-effect evaporation is realized; when the switching valve I is closed, the switching valve II and the switching valve III are opened, and single-effect evaporation is realized.

8. The process of claim 6, wherein: the steam circulation mode of the multi-effect evaporation is as follows: and after steam evaporated from the feed liquid in the second single-effect evaporator is separated by the second vapor-liquid separator, the discharged steam enters a steam compressor, and the steam is compressed in the steam compressor, heated and output and returns to the first single-effect evaporator to be used as heating steam, so that the circulation of the steam is completed.

9. the process of claim 6, wherein: the steam circulation mode of the single-effect evaporation is as follows: the primary steam pressurized and heated by the steam compressor simultaneously enters each single-effect evaporator, secondary steam with different quantities is evaporated from the feed liquid of each single-effect evaporator, and the primary steam is condensed into water; the secondary steam is purified and separated by a steam-liquid separator matched with each single-effect evaporator respectively to evaporate tertiary steam, and the secondary steam is condensed into water; and the tertiary steam is respectively output from a steam outlet of the steam-liquid separator, is combined and then enters the steam compressor again, and the tertiary steam is pressurized and heated in the steam compressor and then enters each single-effect evaporator to complete the evaporation cycle.

Technical Field

The invention relates to the technical field of MVR devices, in particular to an MVR system and a method for realizing large-amplitude adjustment of a yield range by interconversion between single-effect evaporation and multi-effect evaporation.

Background

the MVR evaporation technology has a hundred years history and is widely applied to various industries. Compared with the traditional device which uses steam as energy source to evaporate, the MVR evaporation device can save more than 70% of energy source, and is more energy-saving and environment-friendly. At present, MVR compressors are mainly classified into positive displacement compressors, centrifugal compressors, and high-speed centrifugal compressors in terms of compression form, wherein the high-speed centrifugal compressors are widely applied due to advantages of high efficiency, large temperature rise, small volume, low noise, and the like.

The flow range of the high-speed centrifugal compressor is generally 65% -105% of the design flow, the design flow of the compressor usually meets the upper limit of the flow as the basis, if the flow is lower than the lower limit of the operation range in the production process, surging and other phenomena can occur, the normal work of the compressor is affected, the requirements of enterprises with large capacity change and long-term continuous production are difficult to meet, and for the individual enterprises, a scheme that a plurality of compressors are used in parallel is adopted, so that the investment cost and the management cost are increased greatly.

the method for switching the CN108245912A multi-effect evaporation and MVR system comprises the following steps: the invention provides a method for replacing MVR (mechanical vapor recompression) by multi-effect evaporation of raw steam when a steam compressor fails, which is a method for mutually switching a multi-effect evaporation device using the raw steam and an MVR device.

CN104667550A a MVR continuous evaporation system: the invention provides a method for stably controlling the temperature, the pressure, the flow and the liquid level of an MVR device, which is a method for stably controlling the MVR device through a detection instrument and a control valve and can not solve various problems caused when the change amplitude of the evaporation yield of the MVR exceeds the working range of a compressor.

CN103775353A is a single-stage high-speed centrifugal compressor and method capable of realizing series development; according to the invention, the rotating speed of the centrifugal compressor, the mounting angle of the adjustable inlet guide vane of the centrifugal compressor and the mounting angle of the adjustable radial vane diffuser are jointly adjusted, different pressure ratios are realized by using a single centrifugal compressor, and finally the centrifugal compressor has higher efficiency within a certain working condition range. However, the method realizes the application to different working conditions by changing the centrifugal compressor, and the problem of limited applicable adjustment range inevitably exists.

In summary, in the prior art, for some enterprises with large capacity variation and requiring long-term continuous production, how to better set the production process without greatly changing the devices and equipment is a technical problem to be solved urgently to adjust the yield range and adapt to various working conditions occurring in the production process.

Disclosure of Invention

For an MVR device taking a vapor compressor (a high-speed centrifugal compressor) as a core in the prior art, the invention mainly aims at the characteristic that the stable flow range of the high-speed centrifugal compressor is 65-105 percent, and provides a system for adjusting the yield range of the device by switching single-effect and multi-effect operation modes of vapor and a process method of the system;

the invention discloses an MVR system capable of greatly adjusting the evaporation yield range, which mainly comprises a preheater arranged at the feed liquid inlet end, at least 2 single-effect evaporators connected in series and used for concentrating the feed liquid, a plurality of vapor-liquid separators respectively matched with each single-effect evaporator for use, and a vapor compressor for providing vapor compression, temperature rise and circulation for the system, wherein each single-effect evaporator is respectively provided with a vapor inlet; each vapor-liquid separator is provided with a vapor outlet, and the vapor compressor is provided with a vapor inlet and a vapor outlet; on the basis, a pipeline and a switching valve are additionally arranged, and the method comprises the following specific steps: a switching valve I is arranged on a steam conveying pipeline between the first steam-liquid separator and the second single-effect evaporator; a branch pipeline II is additionally arranged on a pipeline between the steam outlet of the first steam-liquid separator and the switching valve I, the other end of the branch pipeline II is communicated with a pipeline of a steam inlet of the steam compressor, and the switching valve II is arranged on the branch pipeline II; and a branch pipeline III is additionally arranged on a pipeline between the steam inlet of the second single-effect evaporator and the switching valve I, the other end of the branch pipeline III is communicated with a pipeline of the steam outlet of the steam compressor, and the switching valve III is arranged on the branch pipeline III.

For the above-mentioned technical scheme, specifically, through the setting of above-mentioned diverter valve I, diverter valve II and diverter valve III and corresponding pipeline I, pipeline II and pipeline III, can realize the interconversion of single-effect evaporation and multiple-effect evaporation to the purpose of realizing adjusting MVR device evaporation output scope is the core of this system, wherein:

when the switching valve I is opened and the switching valve II and the switching valve III are closed, the first single-effect evaporator and the second single-effect evaporator are in a series connection mode, a steam inlet of the first single-effect evaporator is communicated with a steam outlet of the steam compressor, and a steam outlet of the second steam-liquid separator is communicated with a steam inlet of the steam compressor; when the switching valve I is closed and the switching valve II and the switching valve III are opened, the first single-effect evaporator and the second single-effect evaporator are in a parallel mode, the steam outlets of the first vapor-liquid separator and the second vapor-liquid separator are respectively communicated with the steam inlet of the vapor compressor, and the steam inlets of the first single-effect evaporator and the second single-effect evaporator are respectively communicated with the steam outlet of the vapor compressor. (1) The multi-effect evaporation is characterized by at least comprising two single-effect evaporators connected in series, namely a first single-effect evaporator and a second single-effect evaporator are in a series connection mode, a steam outlet of a steam compressor is communicated with a steam inlet of the first single-effect evaporator, and a steam inlet of the steam compressor is communicated with a steam outlet of the second single-effect evaporator, namely the multi-effect series connection mode; in addition, a third single effect evaporator or more may be included. (2) The single-effect evaporation is that the first single-effect evaporator and the second single-effect evaporator are in a parallel mode, steam outlets of the first vapor-liquid separator and the second vapor-liquid separator are respectively communicated with a steam inlet of the vapor compressor, steam inlets of the first single-effect evaporator and the second single-effect evaporator are respectively communicated with a steam outlet of the vapor compressor, and in addition, a third single-effect evaporator or more single-effect evaporators can be included.

More preferably, the vapor compressor is a high-speed centrifugal compressor.

In the embodiment of the application, the evaporator is a falling film evaporator; virtually all MVR evaporator formats are suitable for use in the present invention.

further, multi-effect evaporator in this application embodiment be comparatively the double-effect evaporator who uses often (double-effect evaporator, single-effect evaporator's quantity is 2), double-effect evaporator in:

(1) A switching valve I is arranged on a pipeline between the top steam outlet of the first steam-liquid separator (namely the first steam-liquid separator) and the top steam inlet of the second-effect evaporator (namely the second evaporator);

(2) a branch pipeline II is additionally arranged on a pipeline between a top steam outlet of the first steam-liquid separator and the switching valve I, the other end of the branch pipeline II is communicated with a pipeline of a steam inlet of the steam compressor, and the switching valve II is arranged on the branch pipeline II;

(3) A branch pipeline III is additionally arranged on a pipeline between a steam inlet of the double-effect evaporator and the switching valve I, the other end of the branch pipeline III is communicated with a pipeline of a steam outlet of the steam compressor, and the switching valve III is arranged on the branch pipeline III.

The second aspect of the invention discloses a process method for greatly adjusting the evaporation yield range of an MVR device, which comprises the following specific steps: the MVR system is used for realizing the interconversion of single-effect evaporation and multi-effect evaporation by controlling the opening and closing of the switching valve I, the switching valve II and the switching valve III, thereby realizing the purpose of adjusting the yield of the MVR device;

Preferably, when the multi-effect evaporator is a double-effect evaporator formed by connecting 2 single-effect evaporators in series, the opening and closing modes of the switching valve I, the switching valve II and the switching valve III are controlled as follows:

When the switching valve I9 is opened and the switching valve II10 and the switching valve III11 are closed, multi-effect evaporation, namely a multi-effect series mode, is realized;

When the switching valve I9 is closed and the switching valves II10 and III11 are opened, single-effect evaporation, namely a single-effect mode of parallel connection of steam, is realized.

Further, the steam cycle process of the single-effect evaporation is as follows: the primary steam pressurized and heated by the steam compressor simultaneously enters each single-effect evaporator, different amounts of secondary steam are evaporated from the feed liquid of each single-effect evaporator, and the primary steam is condensed into water; the secondary steam is purified and separated by a steam-liquid separator matched with each single-effect evaporator respectively to evaporate tertiary steam, and the secondary steam is condensed into water; and the tertiary steam is respectively output from a steam outlet of the steam-liquid separator, is combined and then enters the steam compressor again, and the tertiary steam is pressurized and heated in the steam compressor and then enters each single-effect evaporator to complete the evaporation cycle.

Further, the steam circulation mode of the multi-effect evaporation comprises the following processes: the steam evaporated from the feed liquid in the second single-effect evaporator is separated by the second vapor-liquid separator, the steam enters the vapor compressor, and is compressed in the vapor compressor, heated and output, and returns to the first single-effect evaporator (as described above), and is used as heating steam, thus providing circulation of the steam.

Furthermore, the system is also provided with a vacuum pump for maintaining the vacuum degree of the whole system so as to achieve the stable evaporation state of the system. The system is also provided with a circulating pump for realizing the conveying of the feed liquid in the system.

The method has the advantages that the method for adjusting the yield of the MVR device through the interconversion of the single-effect evaporation and the multi-effect evaporation enables the vapor compressor to stably work under a lower load, and the specific embodiment provides an implementation scheme under the working condition of 50% of capacity, so that the MVR system can effectively achieve the technical effect of stable operation under the working condition of capacity reduction.

Drawings

FIG. 1 is a prior art MVR dual effect evaporation apparatus;

FIG. 2 is a view of the MVR dual-effect evaporation apparatus of example 2; namely, the switching valve I9 is opened, and the switching valves II10 and III11 are closed;

FIG. 3 is a view of the MVR dual-effect evaporation apparatus of example 2; namely, the switching valve I9 is closed, and the switching valves II10 and III11 are open;

FIG. 4. MVR triple effect evaporation device of the prior art;

FIG. 5 is a MVR triple effect evaporation unit of example 3; namely, the switching valve I9 is opened, and the switching valves II10 and III11 are closed;

FIG. 6 is a MVR triple effect evaporation unit of example 3; namely, the switching valve I9 is closed, and the switching valves II10 and III11 are open;

wherein: 1 preheater, 2 one-effect evaporators, 21 one-effect evaporator bottom outlets, 22 one-effect evaporator top feed liquid inlets, 23 one-effect evaporator top steam inlets, 24 one-effect evaporator condensed water outlets, 3 one-effect vapor-liquid separators, 31 one-effect separator bottom outlets and 32 one-effect vapor-liquid separator top outlets; 4 a first-effect circulating pump, 5 a second-effect evaporator, 51 a second-effect evaporator bottom outlet, 52 a second-effect evaporator top feed liquid inlet, 53a second-effect evaporator top steam inlet, 54 a second-effect evaporator condensed water outlet, 6 a second-effect vapor-liquid separator, 61 a second-effect separator bottom outlet, 62 a second-effect vapor-liquid separator top outlet; 7 two-effect circulating pump, 8 steam compressor, 9 switching valve I, 10 switching valve II, 11 switching valve III; 12, a triple-effect evaporator; a bottom material liquid inlet of the 121 triple-effect evaporator, a top steam inlet of the 122 triple-effect evaporator, a condensed water outlet of the 123 triple-effect evaporator, a 13 triple-effect vapor-liquid separator, a bottom material liquid outlet of the 131 triple-effect vapor-liquid separator, a top steam outlet of the 132 triple-effect vapor-liquid separator and a 14 triple-effect circulating pump.

Detailed Description

specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

spatially relative terms, such as "lower," "below," "lower," "upper," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures.

In this document, the terms "first", "second", etc. are used to distinguish two different elements or portions, and are not used to define a particular position or relative relationship. In other words, the terms "first," "second," and the like may also be interchanged with one another in some embodiments.

The MVR evaporation device is limited by the operation range of the compressor, generally adopts single effect and double effect, and is not commonly used in the MVR evaporation device with three or more effects; however, those skilled in the art can derive the method of the present invention from the implementation of specific embodiments to adapt the method to specific implementation procedures, thereby adapting to other similar multi-effect evaporation systems.

The multi-effect evaporation is a series evaporation operation which takes secondary steam of a previous effect as heating steam of a next effect. In multi-effect evaporation, the operating pressure, corresponding heating steam temperature and solution boiling point of each effect are sequentially reduced. The vapor compressor used in this example was a high-speed centrifugal compressor, and the evaporator was a multi-effect falling film evaporator. The system is also provided with a conventional vacuum pump for maintaining the vacuum degree of the whole system so as to achieve a stable evaporation state of the system.