阅读说明：本技术 一种用于丙烯腈制备的四效蒸发器 (Four-effect evaporator for acrylonitrile preparation ) 是由 石喆 刘清娟 赵娟 武力 李迎辉 石凤玉 李凤强 毛爽 李大伟 于 2019-09-05 设计创作，主要内容包括：本发明涉及一种用于丙烯腈制备的四效蒸发器,包括依次串联设置的一效蒸发器、二效蒸发器、三效蒸发器和四效蒸发器；所述一效蒸发器底部设置有用于其底部溶液循环换热的一效换热器,所述二效蒸发器底部设置有用于其底部溶液循环换热的二效换热器,所述三效蒸发器底部设置有用于其底部溶液循环换热的三效换热器,所述四效蒸发器底部设置有用于其底部溶液循环换热的四效换热器,以及输出塔底残液的残液泵；所述四效蒸发器中可选择的切出其中一个蒸发器及与其相配的换热器。根据本发明,能够在任一一效蒸发器、换热器检修清洗时,而其它各效蒸发器、换热器保持正常运行。(The invention relates to a four-effect evaporator for acrylonitrile preparation, which comprises a first-effect evaporator, a second-effect evaporator, a third-effect evaporator and a four-effect evaporator which are sequentially connected in series; the bottom of the first-effect evaporator is provided with a first-effect heat exchanger for circulating heat exchange of a solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator is provided with a second-effect heat exchanger for circulating heat exchange of the solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator is provided with a third-effect heat exchanger for circulating heat exchange of the solution at the bottom of the third-effect evaporator, the bottom of the fourth-effect evaporator is provided with a fourth-effect heat exchanger for circulating heat exchange of the solution at; one of the four-effect evaporators and the heat exchanger matched with the evaporator can be selectively cut out. According to the invention, when any one-effect evaporator and heat exchanger are overhauled and cleaned, other evaporators and heat exchangers can keep normal operation.)

1. A four-effect evaporator for acrylonitrile preparation is characterized by comprising a first-effect evaporator (11), a second-effect evaporator (12), a third-effect evaporator (13) and a four-effect evaporator (14) which are sequentially connected in series;

the bottom of the first-effect evaporator is provided with a first-effect heat exchanger (111) for circulating heat exchange of a solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator is provided with a second-effect heat exchanger (121) for circulating heat exchange of the solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator is provided with a third-effect heat exchanger (131) for circulating heat exchange of the solution at the bottom of the third-effect evaporator, the bottom of the fourth-effect evaporator is provided with a fourth-effect heat exchanger (141) for circulating heat exchange of the solution;

one of the four-effect evaporators and the heat exchanger matched with the evaporator can be selectively cut out.

2. The four-effect evaporator according to claim 1, wherein a first communication pipeline (1m) is connected between the first-effect evaporator inlet material line and the second-effect evaporator inlet material line, and a first cut-off valve (11m) for controlling the cut-off of the first communication pipeline is arranged on the first communication pipeline;

a second communicating pipeline (1a) is connected between the inlet steam line of the first-effect heat exchanger and the inlet steam line of the second-effect heat exchanger, and a second cut-off valve (11a) for controlling the on-off of the second communicating pipeline is arranged on the second communicating pipeline.

3. The four-effect evaporator according to claim 1, wherein a third communication pipeline (1c) is connected between the second-effect evaporator inlet material line and the third-effect evaporator inlet material line, and a third cut-off valve (11c) for controlling the on-off of the third communication pipeline is arranged on the third communication pipeline;

a fourth communicating pipeline (1f) is connected between the inlet steam line of the two-effect heat exchanger and the inlet steam line of the three-effect heat exchanger, and a fourth cut-off valve (11f) for controlling the on-off of the fourth communicating pipeline is arranged on the fourth communicating pipeline.

4. The four-effect evaporator according to claim 1, wherein a fifth communication pipeline (1g) is connected between the three-effect evaporator inlet material line and the four-effect evaporator inlet material line, and a fifth cut-off valve (11g) for controlling the on-off of the fifth communication pipeline is arranged on the fifth communication pipeline;

and a sixth communication pipeline (1j) is connected between the inlet steam line of the three-effect heat exchanger and the inlet steam line of the four-effect heat exchanger, and a sixth cut-off valve (11j) for controlling the on-off of the sixth communication pipeline is arranged on the sixth communication pipeline.

5. The four-effect evaporator according to claim 1, wherein a seventh communication pipeline (1h) is connected between a circulating pump inlet material line connected with the inlet of the three-effect heat exchanger and a residual liquid pump inlet material line at the bottom of the four-effect evaporator, and a seventh cut-off valve (11h) for controlling the on-off of the seventh communication pipeline is arranged on the seventh communication pipeline;

an eighth communication pipeline (1k) is connected between the inlet steam line of the four-effect heat exchanger and the inlet steam line of the four-evaporator distillate condenser, and an eighth control valve (11k) for controlling the on-off of the eighth communication pipeline is arranged on the eighth communication pipeline.

6. The four-effect evaporator according to any one of claims 1 to 5, wherein a one-effect condensate pump (2a) is further disposed on the outlet line of the one-effect heat exchanger, a two-effect condensate pump (2b) is further disposed on the outlet line of the two-effect heat exchanger, a three-effect condensate pump (2c) is further disposed on the outlet line of the three-effect heat exchanger, and a four-effect condensate pump (2d) is further disposed on the outlet line of the four-effect heat exchanger;

and outlet pipelines of the two-effect condensate pump, the three-effect condensate pump and the four-effect condensate pump are respectively provided with a flowmeter (3).

7. The four-effect evaporator according to claim 6, wherein a ninth communication pipeline (1b) is arranged between the first-effect condensate pump inlet condensate line and the second-effect condensate pump inlet condensate line, and a ninth cut-off valve (11b) for controlling the on-off of the ninth communication pipeline is arranged on the ninth communication pipeline.

Technical Field

The invention relates to the field of chemical industry, in particular to a four-effect evaporator for preparing acrylonitrile.

Background

The production technology of acrylonitrile at home and abroad mainly adopts a propylene ammoxidation method. The process is developed for more than 50 years, and the process technology is mature. Since the advent, there has been no major improvement in the process, mainly aiming at the research of novel catalysts and the development of novel fluidized bed reactors, and simultaneously developing the process technology improvement aiming at the purposes of energy saving, consumption reduction, environmental protection and the like to improve the efficiency of the device. The propylene ammoxidation method has the advantages of easily obtained raw materials, simple process, stable operation, convenient product refining, low product cost and the like.

In a four-effect evaporation unit in the existing domestic acrylonitrile production device, a gas-phase product separated by an evaporator contains a large amount of polymers due to liquid foam carried by high flow velocity, so that a two-effect heat exchanger, a three-effect heat exchanger and a four-effect heat exchanger are easy to block, the two-effect heat exchanger, the three-effect heat exchanger and the four-effect heat exchanger need to be cleaned once every 3-6 months, and when any one heat exchanger is cleaned, the four-effect evaporator needs to stop running, so that the long-period stable running of the device is influenced.

Disclosure of Invention

The invention aims to provide a four-effect evaporator for acrylonitrile preparation, which can be stably operated for a long time.

In order to realize the aim, the invention provides a four-effect evaporator for preparing acrylonitrile, which comprises a first-effect evaporator, a second-effect evaporator, a third-effect evaporator and a four-effect evaporator which are sequentially connected in series;

the bottom of the first-effect evaporator is provided with a first-effect heat exchanger for circulating heat exchange of a solution at the bottom of the first-effect evaporator, the bottom of the second-effect evaporator is provided with a second-effect heat exchanger for circulating heat exchange of the solution at the bottom of the second-effect evaporator, the bottom of the third-effect evaporator is provided with a third-effect heat exchanger for circulating heat exchange of the solution at the bottom of the third-effect evaporator, the bottom of the fourth-effect evaporator is provided with a fourth-effect heat exchanger for circulating heat exchange of the solution at the;

one of the four-effect evaporators and the heat exchanger matched with the evaporator can be selectively cut out.

According to one aspect of the invention, a first communication pipeline is connected between the first-effect evaporator inlet material line and the second-effect evaporator inlet material line, and a first cut-off valve for controlling the first communication pipeline to be cut off is arranged on the first communication pipeline;

a second communicating pipeline is connected between the first-effect heat exchanger inlet steam line and the second-effect heat exchanger inlet steam line, and a second cut-off valve for controlling the on-off of the second communicating pipeline is arranged on the second communicating pipeline.

According to one aspect of the invention, a third communication pipeline is connected between the second-effect evaporator inlet material line and the third-effect evaporator inlet material line, and a third cut-off valve for controlling the on-off of the third communication pipeline is arranged on the third communication pipeline;

a fourth communicating pipeline is connected between the inlet steam line of the two-effect heat exchanger and the inlet steam line of the three-effect heat exchanger, and a fourth cut-off valve for controlling the on-off of the fourth communicating pipeline is arranged on the fourth communicating pipeline.

According to one aspect of the invention, a fifth communication pipeline is connected between the three-effect evaporator inlet material line and the four-effect evaporator inlet material line, and a fifth cut-off valve for controlling the on-off of the fifth communication pipeline is arranged on the fifth communication pipeline;

and a sixth communicating pipeline is connected between the inlet steam line of the triple-effect heat exchanger and the inlet steam line of the quadruple-effect heat exchanger, and a sixth cut-off valve for controlling the on-off of the sixth communicating pipeline is arranged on the sixth communicating pipeline.

According to one aspect of the invention, a seventh communication pipeline is connected between a circulating pump inlet material line connected with an inlet of the three-effect heat exchanger and a residual liquid pump inlet material line at the bottom of the four evaporator, and a seventh cut-off valve for controlling the on-off of the seventh communication pipeline is arranged on the seventh communication pipeline;

an eighth communicating pipeline is connected between the inlet steam line of the four-effect heat exchanger and the inlet steam line of the four-evaporator distillate condenser, and an eighth control valve for controlling the on-off of the eighth communicating pipeline is arranged on the eighth communicating pipeline.

According to one aspect of the invention, a primary-effect condensate pump is further arranged on an outlet pipeline of the primary-effect heat exchanger, a secondary-effect condensate pump is further arranged on an outlet pipeline of the secondary-effect heat exchanger, a tertiary-effect condensate pump is further arranged on an outlet pipeline of the tertiary-effect heat exchanger, and a four-effect condensate pump is further arranged on an outlet pipeline of the four-effect heat exchanger;

and outlet pipelines of the two-effect condensate pump, the three-effect condensate pump and the four-effect condensate pump are respectively provided with a flowmeter.

According to one aspect of the invention, a ninth communication pipeline is arranged between the first-effect condensate pump inlet condensate line and the second-effect condensate pump inlet condensate line, and a ninth cut-off valve for controlling the on-off of the ninth communication pipeline is arranged on the ninth communication pipeline.

According to a scheme of the invention, by the method for switching out any one-effect evaporator and heat exchanger provided by the invention, if one-effect heat exchanger or evaporator is blocked, the one-effect evaporator and the heat exchanger can be switched out and then overhauled and cleaned, and other one-effect evaporators and heat exchangers can be kept in normal operation. Thereby guaranteed the quadruple effect evaporation unit, can not take place to block up because of one of them effect, and the whole quadruple effect evaporation unit that leads to stops up, and then guaranteed the long period steady operation of acrylonitrile device quadruple effect evaporation unit.

According to the scheme of the invention, after the flow meter is additionally arranged at the outlet of the condensate pump of the two-three-four-effect evaporator, the metering condition of the flow meter can be directly used for accurately judging which effect heat exchanger shell pass is blocked, and then a corresponding switching maintenance scheme is adopted.

Drawings

Fig. 1 schematically shows a block diagram of a four-effect evaporator according to an embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

As shown in fig. 1, according to one embodiment of the present invention, the four-effect evaporator for producing acrylonitrile of the present invention comprises a one-effect evaporator 11, a two-effect evaporator 12, a three-effect evaporator 13 and a four-effect evaporator 14, which are sequentially arranged in series. In this embodiment, the bottom of the first-effect evaporator 11 is provided with a first-effect heat exchanger 111 for circulating heat exchange of the solution at the bottom thereof, the bottom of the second-effect evaporator 12 is provided with a second-effect heat exchanger 121 for circulating heat exchange of the solution at the bottom thereof, the bottom of the third-effect evaporator 13 is provided with a third-effect heat exchanger 131 for circulating heat exchange of the solution at the bottom thereof, and the bottom of the fourth-effect evaporator 14 is provided with a fourth-effect heat exchanger 141 for circulating heat exchange of the solution at the bottom thereof.

As shown in fig. 1, according to one embodiment of the present invention, the tower of the first effect evaporator 11 is provided with a first pipeline 112 connecting the first effect evaporator 11 and a first residual liquid pump 113, the first residual liquid pump 113 and the first effect heat exchanger 111 are connected with a second pipeline 114, and the tower liquid passing through the first effect heat exchanger 111 is returned to the evaporator from the side of the first effect evaporator 11. External low-pressure steam is input into the first-effect heat exchanger 111 through the third pipeline 117, exchanges heat with tower bottoms flowing through the first-effect heat exchanger, and is conveyed to the normal-pressure steam condensate tank. The upper part of the first-effect evaporator 11 is input into the tower bottom liquid of the recovery tower through a fourth pipeline 118.

As shown in FIG. 1, according to one embodiment of the present invention, the tower of the second effect evaporator 12 is provided with a fifth pipeline 122 connecting the second effect evaporator 12 with a second residual liquid pump 123, the second residual liquid pump 123 is connected with the second effect heat exchanger 121 with a sixth pipeline 124, and the tower liquid passing through the second effect heat exchanger 121 is returned back to the evaporator from the side line of the second effect evaporator 12. A seventh pipeline 115 is led out of the first pipeline 112 to send part of the tower bottoms in the first pipeline 112 to the upper part of the second effect evaporator 12. An eighth pipeline 116 is led out from the top of the first-effect evaporator 11 and communicated with the second-effect heat exchanger 121, so that the material flow output from the top of the first-effect evaporator 11 exchanges heat with the tower bottom liquid in the second-effect heat exchanger 121 and is sent to the low-pressure steam condensate tank. In the present embodiment, a tenth communication line 1e is connected between the first pipe line 112 and the fifth pipe line 122, and a tenth shutoff valve 11e is provided on the ninth communication line.

As shown in fig. 1, according to one embodiment of the present invention, the tower of the triple-effect evaporator 13 is provided with a ninth pipeline 132 connecting the triple-effect evaporator 13 with the third raffinate pump 133, the third raffinate pump 133 is connected with the triple-effect heat exchanger 131 with a tenth pipeline 134, and the tower liquid passing through the triple-effect heat exchanger 131 is returned to the evaporator from the side of the triple-effect evaporator 13. An eleventh line 125 leads from the fifth line 122 to send a part of the column bottoms in the fifth line 122 to the upper part of the triple-effect evaporator 13. A twelfth pipeline 126 is led out from the top of the second-effect evaporator 12 and communicated with the three-effect heat exchanger 131, so that the material flow output from the top of the second-effect evaporator 12 exchanges heat with the tower bottom liquid in the three-effect heat exchanger 131 and is sent to the low-pressure steam condensate tank.

As shown in fig. 1, according to an embodiment of the present invention, the tower of the four-effect evaporator 14 is provided with a thirteenth pipeline 142 connecting the four-effect evaporator 14 and a fourth residual liquid pump 143, the fourth residual liquid pump 143 and the four-effect heat exchanger 141 are connected with a fourteenth pipeline 144, and the tower liquid passing through the four-effect heat exchanger 141 is returned to the evaporator from the side of the four-effect evaporator 14. A fifteenth line 135 leads from the ninth line 132 to feed a part of the column bottoms in the ninth line 132 to the upper part of the four-effect evaporator 14. And a sixteenth pipeline 136 is led out from the top of the three-effect evaporator 13 and communicated with the four-effect heat exchanger 141, so that the material flow output from the top of the three-effect evaporator 13 exchanges heat with the tower bottom liquid in the four-effect heat exchanger 141 and is sent to the low-pressure steam condensate tank. A seventeenth pipeline 145 is led out from the thirteenth pipeline 142 to convey part of the tower bottom liquid to the subsequent section, and an eighteenth pipeline 146 is led out from the top of the four-effect evaporator 14 to convey the material flow led out from the top of the four-effect evaporator 14 to the subsequent section for treatment.

As shown in fig. 1, one of the four-effect evaporators of the present invention and its associated heat exchanger can be selectively cut out according to one embodiment of the present invention.

As shown in figure 1, the first-effect evaporator and the first-effect heat exchanger are in short circuit by additionally arranging a communication pipeline, so that the second-effect evaporator, the third-effect evaporator and the fourth-effect evaporator, as well as the second-effect heat exchanger, the third-effect heat exchanger and the fourth-effect heat exchanger can normally operate. In the present embodiment, a first communication line 1m is connected between the first-effect evaporator inlet material line (i.e., the fourth line 118) and the second-effect evaporator inlet material line (i.e., the seventh line 115), and the first communication line 1m is provided with a first shut-off valve 11m for controlling the on/off of the first communication line. In this embodiment, a second communication pipeline 1a is connected between an inlet steam line of the first-effect heat exchanger 111 (i.e. a section where the third pipeline 117 is connected to the inlet of the first-effect heat exchanger 111) and an inlet steam line of the second-effect heat exchanger (i.e. a section where the eighth pipeline 116 is connected to the inlet of the second-effect heat exchanger 121), and a second cut-off valve 11a for controlling the on-off of the second communication pipeline 1a is arranged on the second communication pipeline. In this embodiment, a ninth communication pipeline 1b is connected between a first-effect condensate pump inlet condensate line (i.e., a section where the third pipeline 117 is connected to the outlet of the first-effect heat exchanger 111) at the outlet of the first-effect heat exchanger 111 and a second-effect condensate pump inlet condensate line (i.e., a section where the eighth pipeline 116 is connected to the outlet of the second-effect heat exchanger 121) at the outlet of the second-effect heat exchanger, and the ninth communication pipeline 1b is provided with a ninth cut-off valve 11b for controlling the on-off state of the ninth communication pipeline. In the present embodiment, when the respective shut valves on the first communication line 1m, the second communication line 1a and the ninth communication line 1b are connected, the first-effect evaporator 11 and the corresponding first-effect heat exchanger 111 can be short-circuited by the communication lines, so that the first-effect evaporator 11 and the first-effect heat exchanger 111 are switched off in the operating state, and the second-effect evaporator 12, the third-effect evaporator 13 and the fourth-effect evaporator 14, and the corresponding second-effect heat exchanger 121, the third-effect heat exchanger 131 and the fourth-effect heat exchanger 141 can continue to operate normally.

As shown in fig. 1, according to an embodiment of the present invention, the first-effect evaporator, the third-effect evaporator, the fourth-effect evaporator, and the first-effect heat exchanger, the third-effect heat exchanger, and the fourth-effect heat exchanger are normally operated by short-circuiting the second-effect evaporator and the second-effect heat exchanger by adding a communication line. In the present embodiment, a third communication line 1c is connected between the inlet material line (i.e., the seventh pipeline 115) of the second effect evaporator 12 and the inlet material line (i.e., the eleventh pipeline 125) of the third effect evaporator 13, and the third communication line 1c is provided with a third cut-off valve 11c for controlling the on/off of the third communication line. In this embodiment, a fourth communication pipeline 1f is connected between an inlet steam line of the two-effect heat exchanger 121 (i.e., a section of the eighth pipeline 116 connected to the inlet of the two-effect heat exchanger 121) and an inlet steam line of the three-effect heat exchanger (i.e., a section of the twelfth pipeline 126 connected to the inlet of the three-effect heat exchanger), and a fourth cut-off valve 11f for controlling the on-off of the fourth communication pipeline 1f is arranged on the fourth communication pipeline 1 f. In the present embodiment, when the respective shut valves on the third communication line 1c and the fourth communication line 1f are connected, the second-effect evaporator 12 and the corresponding second-effect heat exchanger 121 can be short-circuited by the communication lines, so that the second-effect evaporator 12 and the second-effect heat exchanger 121 are switched off in the working state, and the first-effect evaporator 11, the third-effect evaporator 13 and the fourth-effect evaporator 14, and the corresponding first-effect heat exchanger 111, the third-effect heat exchanger 131 and the fourth-effect heat exchanger 141 can continue to operate normally.

As shown in fig. 1, according to an embodiment of the present invention, the triple-effect evaporator and the triple-effect heat exchanger are short-circuited by adding a communication pipeline, so that the single-effect evaporator, the double-effect evaporator, the four-effect evaporator, and the single-effect heat exchanger, the double-effect heat exchanger, and the four-effect heat exchanger operate normally. In the present embodiment, a fifth communication pipeline 1g is added between the triple-effect evaporator inlet material line (i.e., the eleventh pipeline 125) and the fourth-effect evaporator inlet material line (i.e., the fifteenth pipeline 135), and the fifth communication pipeline 1g is provided with a fifth cut-off valve 11g for controlling the on/off of the fifth communication pipeline. In this embodiment, a sixth communication pipeline 1j is added between an inlet steam line of the three-effect heat exchanger 131 (i.e., a section of the twelfth pipeline 126 connected to the inlet of the three-effect heat exchanger) and an inlet steam line of the four-effect heat exchanger 141 (i.e., a section of the sixteenth pipeline 136 connected to the inlet of the four-effect heat exchanger 141), and the sixth communication pipeline 1j is provided with a sixth cut-off valve 11j for controlling the on-off state of the sixth cut-off valve. In the present embodiment, when the respective shut valves on the fifth communication line 1g and the sixth communication line 1j are connected, the triple-effect evaporator 13 and the corresponding triple-effect heat exchanger 131 can be short-circuited by the communication lines, so that the triple-effect evaporator 13 and the triple-effect heat exchanger 131 are switched off in the working state, and the single-effect evaporator 11, the double-effect evaporator 12 and the four-effect evaporator 14, and the corresponding single-effect heat exchanger 111, the double-effect heat exchanger 121 and the four-effect heat exchanger 141 can continue to operate normally.

As shown in fig. 1, according to an embodiment of the present invention, the four-effect evaporator and the four-effect heat exchanger are short-circuited by adding a communication pipeline, so that the one-effect evaporator, the two-effect evaporator, the three-effect evaporator, and the one-effect heat exchanger, the two-effect heat exchanger, and the three-effect heat exchanger operate normally. In the present embodiment, a seventh communication line 1h is connected between the ninth line 132 and the seventeenth line 145 (i.e., the residual liquid pump inlet material line at the bottom of the fourth evaporator), and the seventh communication line 1h is provided with a seventh shut-off valve 11h for controlling the on/off of the seventh communication line. In the present embodiment, an eighth communication line 1k is connected between the four-effect heat exchanger inlet steam line (i.e., the section of the sixteenth pipeline 136 connected to the inlet of the four-effect heat exchanger 141) and the four-evaporator distillate condenser inlet steam line (i.e., the eighteenth pipeline 146), and the eighth cut-off valve 11k for controlling the on-off of the eighth communication line 1k is provided. In the present embodiment, when the respective shut valves on the seventh communication line 1h and the eighth communication line 1k are connected, the four-effect evaporator 14 and the corresponding four-effect heat exchanger 141 can be short-circuited by the communication lines, so that the four-effect evaporator 14 and the four-effect heat exchanger 141 are switched off in the operating state, and the first-effect evaporator 11, the second-effect evaporator 12, and the third-effect evaporator 13, and the corresponding first-effect heat exchanger 111, the second-effect heat exchanger 121, and the third-effect heat exchanger 131 can continue to operate normally.

As shown in fig. 1, according to an embodiment of the present invention, a first-effect condensate pump 2a is further disposed on an outlet line of the first-effect heat exchanger 111 (i.e., a section of the third line 117 connected to the outlet of the first-effect heat exchanger 111), a second-effect condensate pump 2b is further disposed on an outlet line of the second-effect heat exchanger 121 (i.e., a section of the eighth line 116 connected to the outlet of the second-effect heat exchanger 121), a third-effect condensate pump 2c is further disposed on an outlet line of the third-effect heat exchanger 131 (i.e., a section of the twelfth line 126 connected to the outlet of the third-effect heat exchanger 131), and a fourth-effect condensate pump 2d is further disposed on an outlet line of the fourth-effect heat exchanger 141 (i.e., a section of the sixteenth line 136 connected. In the present embodiment, one flow meter 3 is provided for each of the outlet lines of the two-effect condensate pump 2b, the three-effect condensate pump 2c, and the four-effect condensate pump 2 d.

The foregoing is merely exemplary of particular aspects of the present invention and devices and structures not specifically described herein are understood to be those of ordinary skill in the art and are intended to be implemented in such conventional ways.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.