A low-temperature multi-effect seawater desalination system using a steam reciprocating pump

Abstract

The present invention discloses a low-temperature multi-effect seawater desalination system using a steam reciprocating pump. The steam reciprocating pump module includes a plurality of serially connected steam reciprocating pumps. The steam reciprocating pump comprises a high-pressure cylinder, a low-pressure cylinder, and a piston. Through the series connection of multiple-stage steam reciprocating pumps, the motive steam is used to drive the steam reciprocating pump to compress and suck the steam. The sucked steam at each stage is directly discharged after compression, and the motive steam is discharged after passing through the last-stage steam reciprocating pump. The discharged motive steam and the newly sucked steam are mixed in the mixing chamber to form heating steam. Without adding additional devices and consuming additional electric energy, the temperature increase and pressure boost of the sucked steam are completed, the direct mixing of the motive steam and the sucked steam is avoided, the flow rate of the motive steam is reduced, and the energy consumption is decreased. Moreover, in this application, the cooling seawater for cooling the secondary steam of the last effect is used as the feed seawater in the multi-effect evaporator group, reducing the loss of available energy and improving the production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of seawater desalination, and more particularly to a low-temperature multi-effect seawater desalination system using a steam reciprocating pump. Background Art

[0002] At present, the world's fresh water resources are seriously insufficient, and seawater desalination can effectively alleviate this problem. As one of the main methods of seawater desalination, the low-temperature multi-effect seawater desalination technology can efficiently utilize low-grade heat sources, has low requirements for pretreatment, and produces fresh water with high quality, and has been widely used. However, since the low-temperature multi-effect seawater desalination technology mainly relies on the phase change of seawater to produce fresh water, at present, a large amount of high-temperature and high-pressure motive steam and low-temperature and low-pressure suction steam are mainly mixed in a steam jet pump to form heating steam with appropriate pressure and temperature, and the heating steam is used to heat the seawater for phase change. This not only consumes a large amount of thermal energy but also has low efficiency, and the available energy loss accounts for more than half of the total loss. The cooling seawater used to cool the secondary steam of the last effect also takes away about 10% of the available energy of the system, resulting in low efficiency of the low-temperature multi-effect seawater desalination system. Summary of the Invention

[0003] In view of the defects existing in the prior art, the present application provides a low-temperature multi-effect seawater desalination system using a steam reciprocating pump to solve the technical problem of low energy utilization of the low-temperature multi-effect seawater desalination system in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solution: A low-temperature multi-effect seawater desalination system using a steam reciprocating pump, comprising a multi-effect evaporator group, a condenser, a mixing chamber and a raw seawater pump, wherein the low-temperature multi-effect seawater desalination system further comprises a steam reciprocating pump module, the multi-effect evaporator group comprises a plurality of serially connected evaporation chambers, the steam reciprocating pump module comprises a plurality of serially connected steam reciprocating pumps, a part of the steam generated by the multi-effect evaporator group is used as suction steam and is transported to the steam reciprocating pump module, the suction steam is compressed and pressurized by motive steam in the steam reciprocating pump module to form new suction steam, wherein the pressure of the motive steam is greater than the pressure of the suction steam, the new suction steam and the new motive steam discharged from the steam reciprocating pump module are mixed in the mixing chamber to form heating steam, the heating steam enters the multi-effect evaporator group to cause the feed seawater to undergo phase change and desalination, the remaining part of the steam generated by the multi-effect evaporator group is transported to the condenser, the raw seawater transported by the raw seawater pump is heated in the condenser to become the feed seawater, and the feed seawater is transported to the multi-effect evaporator group.

[0005] In an embodiment, the low-temperature multi-effect seawater desalination system further comprises a fresh water diversion chamber, a part of the fresh water generated by the multi-effect evaporator enters the fresh water diversion chamber for diversion, and a part of the fresh water in the fresh water diversion chamber enters the boiler, and the remaining fresh water is discharged from the system.

[0006] In one embodiment, the multiple-effect evaporator group includes a first-effect evaporation chamber and a second-effect evaporation chamber connected in series; the low-temperature multiple-effect seawater desalination system further includes a concentrated brine pump, a product water pump and a fan. The concentrated brine pump is used to discharge the concentrated brine generated by the multiple-effect evaporator group from the system, the product water pump is used to discharge the fresh water generated by the system from the system, and the fan is used to convey the suction steam to the steam reciprocating pump module.

[0007] In one embodiment, the first feed seawater inlet of the condenser is connected to the raw seawater pump, the feed seawater outlet of the condenser is connected to the second feed seawater inlet of the first-effect evaporation chamber and the third feed seawater inlet of the second-effect evaporation chamber through a pipeline, the heating steam inlet of the first-effect evaporation chamber is connected to the heating steam outlet of the mixing chamber, the first-effect secondary steam outlet of the first-effect evaporation chamber is connected to the first-effect secondary steam inlet of the second-effect evaporation chamber, the first-effect concentrated brine outlet of the first-effect evaporation chamber is connected to the first-effect concentrated brine inlet of the second-effect evaporation chamber, the first-effect fresh water outlet of the first-effect evaporation chamber is connected to the inlet of the fresh water diversion chamber, the second-effect secondary steam outlet of the second-effect evaporation chamber is respectively connected to the second-effect secondary steam inlet of the condenser and the inlet of the fan, the concentrated brine outlet of the second-effect evaporation chamber is connected to the concentrated brine pump, the first outlet of the fresh water diversion chamber, the second product water outlet of the second-effect evaporation chamber and the first product water outlet of the condenser are connected in series to the product water pump through a pipeline, the second outlet of the fresh water diversion chamber is connected to the boiler, the outlet of the fan is connected to the inlet pipeline of the steam reciprocating pump module, the power steam outlet pipeline of the steam reciprocating pump module is connected to the first inlet of the mixing chamber, and the new suction steam pipeline of the steam reciprocating pump module is connected to the second inlet of the mixing chamber.

[0008] In one embodiment, the steam reciprocating pump includes a low-pressure cylinder and a high-pressure cylinder. The cross-sectional area of the high-pressure cylinder is smaller than that of the low-pressure cylinder. A low-pressure piston and a high-pressure piston are respectively arranged in the low-pressure cylinder and the high-pressure cylinder. The low-pressure piston and the high-pressure piston are connected by a piston rod. The low-pressure piston divides the low-pressure cylinder into a low-pressure cylinder cavity one and a low-pressure cylinder cavity two, and the high-pressure piston divides the high-pressure cylinder into a high-pressure cylinder cavity one and a high-pressure cylinder cavity two. The low-pressure cylinder cavity one and the high-pressure cylinder cavity one are on the same side. A low-pressure cylinder air port one and a low-pressure cylinder air port four are respectively arranged on the left and right sides of the low-pressure cylinder cavity one, a low-pressure cylinder air port two and a low-pressure cylinder air port three are respectively arranged on the left and right sides of the low-pressure cylinder cavity two, a high-pressure cylinder air port one and a high-pressure cylinder air port four are respectively arranged on the left and right sides of the high-pressure cylinder cavity one, and a high-pressure cylinder air port two and a high-pressure cylinder air port three are respectively arranged on the left and right sides of the high-pressure cylinder cavity two. Suction steam is pre-stored in both the low-pressure cylinder cavity one and the low-pressure cylinder cavity two, and power steam is pre-stored in both the high-pressure cylinder cavity one and the high-pressure cylinder cavity two. Each air port is connected to a valve. The valve is a one-way valve, and the valve limits the pressure of the steam entering and leaving the air port.

[0009] In one embodiment, the valves in the steam reciprocating pump module are all solenoid valves, and the steam reciprocating pumps in the steam reciprocating pump module have the same structure.

[0010] In one embodiment, motive steam enters the high-pressure cylinder of the first-stage steam reciprocating pump through the motive steam pipeline. The high-pressure cylinder of the last-stage steam reciprocating pump discharges the new motive steam to the mixing chamber. Suction steam enters the low-pressure cylinder of each stage of the steam reciprocating pump, and the low-pressure cylinder of each stage of the steam reciprocating pump discharges the new suction steam to the mixing chamber to mix with the new motive steam.

[0011] In one embodiment, the high-pressure cylinder port three is connected to the high-pressure cylinder port one of the next-stage steam reciprocating pump, and the high-pressure cylinder port four is connected to the high-pressure cylinder port two of the next-stage steam reciprocating pump. The high-pressure cylinder port one and the high-pressure cylinder port two of the first-stage steam reciprocating pump are both connected to the motive steam pipeline. The high-pressure cylinder port four and the high-pressure cylinder port three of the last-stage steam reciprocating pump are both connected to the new motive steam pipeline. The low-pressure cylinder port one and the low-pressure cylinder port two of each stage of the steam reciprocating pump are both connected to the suction steam pipeline. The low-pressure cylinder port three and the low-pressure cylinder port four of each stage of the steam reciprocating pump are both connected to the new suction steam pipeline.

[0012] In one embodiment, the steam reciprocating pump module includes a first-stage steam reciprocating pump, a second-stage steam reciprocating pump, a third-stage steam reciprocating pump, and a fourth-stage steam reciprocating pump connected in series.

[0013] Compared with the prior art, the beneficial effects in this application are as follows:

[0014] In the present invention, by arranging a steam reciprocating pump module in a low-temperature multi-effect seawater desalination system, the steam reciprocating pump module includes a plurality of steam reciprocating pumps connected in series. The steam reciprocating pump includes a high-pressure cylinder, a low-pressure cylinder, and a piston. Through the series connection of multiple stages of steam reciprocating pumps, motive steam is used to drive the steam reciprocating pump to compress the suction steam. The suction steam of each stage is directly discharged after compression, and the motive steam is discharged after passing through the last-stage steam reciprocating pump. The discharged motive steam and the new suction steam are mixed in the mixing chamber to become heating steam. Without adding additional devices and consuming additional electric energy, the temperature increase and pressure increase of the suction steam are completed, the direct mixing of the motive steam and the suction steam is avoided, the flow rate of the motive steam is reduced, the energy consumption is reduced, and in this application, the cooling seawater for cooling the secondary steam of the last effect is used as the feed seawater in the multi-effect evaporator group, reducing the loss of available energy and improving the production efficiency. Description of the Drawings

[0015] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related accompanying drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 Schematic diagram of a low-temperature multi-effect seawater desalination system using a steam reciprocating pump in an embodiment of the present application;

[0017] Figure 2 Schematic diagram of the structure of a steam reciprocating pump in an embodiment of the present application;

[0018] Figure 3 Schematic diagram of the series connection of four-stage steam reciprocating pumps in an embodiment of the present application.

[0019] Reference numerals: 1, first-effect evaporation chamber; 2, second-effect evaporation chamber; 3, condenser; 4, mixing chamber; 5, fresh water diversion chamber; 6, raw seawater pump; 7, concentrated brine pump; 8, product water pump; 9, fan; 10, first-stage steam reciprocating pump; 11, second-stage steam reciprocating pump; 12, third-stage steam reciprocating pump; 13, fourth-stage steam reciprocating pump; 1X01, first low-pressure cylinder cavity; 1X02, second low-pressure cylinder cavity; 1X03, first high-pressure cylinder cavity; 1X04, second high-pressure cylinder cavity; 1X05, first low-pressure cylinder air port; 1X06, second low-pressure cylinder air port; 1X07, first high-pressure cylinder air port; 1X08, second high-pressure cylinder air port; 1X09, third high-pressure cylinder air port; 1X10, fourth high-pressure cylinder air port; 1X11, third low-pressure cylinder air port; 1X12, fourth low-pressure cylinder air port; where X takes values of 1, 2, 3, 4. Specific embodiments

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0022] Embodiment 1

[0023] As Figure 1As shown in the figure, a low-temperature multi-effect seawater desalination system using a steam reciprocating pump includes a multi-effect evaporator group, a condenser 3, a mixing chamber 4, a fresh water diversion chamber 5, a raw seawater pump 6, a concentrated brine pump 7, a product water pump 8, a fan 9, and a steam reciprocating pump module. The multi-effect evaporator group includes multiple serially connected evaporation chambers. The steam reciprocating pump module includes multiple serially connected steam reciprocating pumps and a valve group. A part of the steam generated by the multi-effect evaporator group is used as suction steam and is transported to the steam reciprocating pump. The suction steam is compressed and pressurized by the motive steam in the steam reciprocating pump module to form new suction steam. The pressure of the motive steam is greater than that of the suction steam. The new suction steam and the new motive steam discharged from the steam reciprocating pump module are mixed in the mixing chamber 4 to form heating steam. The heating steam enters the multi-effect evaporator group to cause the feed seawater to undergo phase change and desalination. The remaining part of the steam generated by the multi-effect evaporator group is transported to the condenser 3 to heat the raw seawater transported by the raw seawater pump 6 into feed seawater, and the feed seawater is transported into the multi-effect evaporator group. In this embodiment, the multi-effect evaporator group includes a first-effect evaporation chamber 1 and a second-effect evaporation chamber 2, and the steam reciprocating pump module includes a first-stage steam reciprocating pump 10, a second-stage steam reciprocating pump 11, a third-stage steam reciprocating pump 12, and a fourth-stage steam reciprocating pump 13.

[0024] The first feed seawater inlet of the condenser 3 is connected to the raw seawater pump 6. The feed seawater outlet of the condenser 3 is connected to the second feed seawater inlet of the first-effect evaporation chamber 1 and the third feed seawater inlet of the second-effect evaporation chamber 2 through a pipeline. The heating steam inlet of the first-effect evaporation chamber 1 is connected to the heating steam outlet of the mixing chamber 4. The first-effect secondary steam outlet of the first-effect evaporation chamber 1 is connected to the first-effect secondary steam inlet of the second-effect evaporation chamber 2. The first-effect concentrated brine outlet of the first-effect evaporation chamber 1 is connected to the first-effect concentrated brine inlet of the second-effect evaporation chamber 2. The first-effect fresh water outlet of the first-effect evaporation chamber 1 is connected to the inlet of the fresh water diversion chamber 5. The second-effect secondary steam outlet of the second-effect evaporation chamber 2 is respectively connected to the second-effect secondary steam inlet of the condenser 3 and the inlet of the fan 9. The concentrated brine outlet of the second-effect evaporation chamber 2 is connected to the concentrated brine pump 7. The first outlet of the fresh water diversion chamber 5, the second product water outlet of the second-effect evaporation chamber 2, and the first product water outlet of the condenser 3 are connected to the product water pump 8 through a pipeline. The second outlet of the fresh water diversion chamber 5 is connected to the boiler. The outlet of the fan 9 is connected to the inlet pipeline of the steam reciprocating pump module. The motive steam outlet pipeline of the steam reciprocating pump module is connected to the first inlet of the mixing chamber 4. The new suction steam pipeline of the steam reciprocating pump module is connected to the second inlet of the mixing chamber 4.

[0025] As Figure 2As shown in the figure, the steam reciprocating pump includes a low-pressure cylinder and a high-pressure cylinder. The cross-sectional area of the high-pressure cylinder is smaller than that of the low-pressure cylinder. A low-pressure piston and a high-pressure piston are respectively arranged in the low-pressure cylinder and the high-pressure cylinder. The low-pressure piston and the high-pressure piston are connected by a piston rod. The low-pressure piston divides the low-pressure cylinder into a first low-pressure cylinder cavity 1X01 and a second low-pressure cylinder cavity 1X02. The high-pressure piston divides the high-pressure cylinder into a first high-pressure cylinder cavity 1X03 and a second high-pressure cylinder cavity 1X04. The first low-pressure cylinder cavity 1X01 and the first high-pressure cylinder cavity 1X03 are on the same side. A first low-pressure cylinder air port 1X05 and a fourth low-pressure cylinder air port 1X12 are respectively arranged on the left and right sides of the first low-pressure cylinder cavity 1X01. A second low-pressure cylinder air port 1X06 and a third low-pressure cylinder air port 1X11 are respectively arranged on the left and right sides of the second low-pressure cylinder cavity 1X02. A first high-pressure cylinder air port 1X07 and a fourth high-pressure cylinder air port 1X10 are respectively arranged on the left and right sides of the first high-pressure cylinder cavity 1X03. A second high-pressure cylinder air port 1X08 and a third high-pressure cylinder air port 1X09 are respectively arranged on the left and right sides of the second high-pressure cylinder cavity 1X04. Wherein the value of X is the stage number of the steam reciprocating pump. Suction steam is pre-stored in both the first low-pressure cylinder cavity 1X01 and the second low-pressure cylinder cavity 1X02. Power steam is pre-stored in both the first high-pressure cylinder cavity 1X03 and the second high-pressure cylinder cavity 1X04. Each air port is connected to a valve, and the valves are all one-way valves, and the valves limit the pressure of the steam entering and leaving the air ports. Different valves form a valve group. For the convenience of controlling the opening of the valves, in this embodiment, the valves are all solenoid valves. Multiple steam reciprocating pumps in the steam reciprocating pump module have the same structure. As Figure 1 , 3 shown, the third high-pressure cylinder air port 1X09 is connected to the first high-pressure cylinder air port 1(X + 1)07, and the fourth high-pressure cylinder air port 1X10 is connected to the second high-pressure cylinder air port 1(X + 1)08. The first high-pressure cylinder air port 1107 and the second high-pressure cylinder air port 1108 in the first-stage steam reciprocating pump, i.e., the first-stage steam reciprocating pump 10, are both connected to the power steam pipeline. The fourth high-pressure cylinder air port 1410 and the third high-pressure cylinder air port 1409 in the last-stage steam reciprocating pump, i.e., the fourth-stage steam reciprocating pump 10, are both connected to the new power steam pipeline. The first low-pressure cylinder air port 1X05 and the second low-pressure cylinder air port 1X06 are both connected to the suction steam pipeline. The third low-pressure cylinder air port 1X11 and the fourth low-pressure cylinder air port 1X12 are both connected to the new suction steam pipeline.

[0026] In this embodiment, the operation process of the low-temperature multi-effect seawater desalination device is as Figure 1As shown in the figure, the raw seawater enters the condenser 3 through the feed seawater pump 6, exchanges heat with part of the new second-effect secondary steam in the condenser 3 to form feed seawater, and the feed seawater enters the first-effect evaporation chamber 1 and the second-effect evaporation chamber 2 respectively through the feed seawater pipeline; in the first-effect evaporation chamber 1, the feed seawater exchanges heat with the heating steam to generate first-effect secondary steam and first-effect concentrated brine, the heating steam condenses into fresh water and enters the fresh water diversion chamber 5, and the first-effect secondary steam and the first-effect concentrated brine both enter the second-effect evaporation chamber 2; in the second-effect evaporation chamber 2, the feed seawater exchanges heat with the first-effect secondary steam to generate second-effect secondary steam and second-effect concentrated brine, the first-effect secondary steam condenses into fresh water, part of the first-effect concentrated brine flashes to generate steam and mixes with the second-effect secondary steam to form new second-effect secondary steam, the remaining part of the first-effect concentrated brine mixes with the second-effect concentrated brine to form concentrated brine, and the concentrated brine is discharged from the system through the concentrated brine pump 7; part of the new second-effect secondary steam enters the condenser 3, exchanges heat with the raw seawater to form fresh water, and the remaining part of the new second-effect secondary steam enters the steam reciprocating pump module through the fan 9 and serves as the suction steam to enter the low-pressure cylinder of the steam reciprocating pump; part of the fresh water in the fresh water diversion chamber 5 enters the boiler to continue the cycle, and the remaining part of the fresh water converges with the fresh water generated in the second-effect evaporation chamber 2 and the fresh water generated in the condenser 3 and is discharged through the product water pump 8; in the steam reciprocating pump module, the motive steam enters the high-pressure cylinder of the first-stage steam reciprocating pump through the motive steam pipeline, and the high-pressure cylinder of the last-stage steam reciprocating pump discharges the new motive steam to the mixing chamber 4, and the low-pressure cylinder of each stage of the steam reciprocating pump discharges the new suction steam to the mixing chamber 4; in the mixing chamber 4, the new motive steam and the new suction steam are mixed to form heating steam and enter the first-effect evaporation chamber 1.

[0027] In an X-class steam reciprocating pump, the cyclic motion of a complete steam reciprocating pump includes two motions. First motion: The motive steam first enters the high-pressure cylinder cavity 1X03 through the high-pressure cylinder air port 1X07. The suction steam enters the low-pressure cylinder cavity 1X01 through the low-pressure cylinder air port 1X05. The motive steam in the high-pressure cylinder drives the high-pressure piston to move. The high-pressure piston drives the low-pressure piston to move. The low-pressure piston compresses the suction steam in the low-pressure cylinder cavity 1X02. When the suction steam in the low-pressure cylinder cavity 1X02 reaches a certain pressure, it is discharged from the low-pressure cylinder air port 1X11 into the mixing chamber 4. The high-pressure piston compresses the motive steam in the high-pressure cylinder cavity 1X04. The motive steam enters the high-pressure cylinder air port 1(X + 1)07 through the high-pressure cylinder air port 1X09, and the above process is repeated. Second motion: The motive steam enters the high-pressure cylinder cavity 1X04 through the high-pressure cylinder air port 1X08. The suction steam enters the low-pressure cylinder cavity 1X02 through the low-pressure cylinder air port 1X06. The motive steam drives the high-pressure piston to move. The high-pressure piston drives the low-pressure piston to move. The low-pressure piston compresses the suction steam in the low-pressure cylinder cavity 1X01. When the suction steam in the low-pressure cylinder cavity 1X01 reaches a certain pressure, it is discharged from the low-pressure cylinder air port 1X12 into the mixing chamber 4. The high-pressure piston compresses the motive steam in the high-pressure cylinder cavity 1X03. The motive steam enters the high-pressure cylinder air port 1X10 through the high-pressure cylinder air port 1X08, and the above process is repeated.

[0028] When the motive steam comes out of the last-stage steam reciprocating pump, i.e., the four-stage steam reciprocating pump 13, it mixes with the suction steam that has been heated and pressurized at each stage in the mixing chamber 4 to form heating steam, which then enters the first-effect evaporation chamber 1. Through the series connection of the four-stage steam reciprocating pumps, the motive steam is used to drive the steam reciprocating pump to compress the suction steam. The suction steam at each stage is directly discharged after being compressed, and the motive steam is discharged after passing through the fourth-stage steam reciprocating pump. The discharged motive steam and the suction steam are mixed in the mixing chamber to become heating steam and enter the first-effect evaporation chamber to function. Without adding additional devices and consuming additional electric energy, the temperature increase and pressure increase of the suction steam are completed, and at the same time, the direct mixing of the motive steam and the suction steam is avoided, and the efficiency is higher than that of the steam jet pump.

[0029] Using the low-temperature multi-effect seawater desalination system in this embodiment, 15 tons of fresh water are produced daily. The motive steam pressure is set at 460 kPa, the heating steam pressure is 19.9 kPa, and the suction steam pressure is 14.4 kPa. Since the pressure difference between the motive steam and the heating steam is relatively large, the cross-sectional area of the low-pressure cylinder of each steam reciprocating pump is 16 times that of the high-pressure cylinder. The volumes of each stage of the steam reciprocating pump are shown in Table 1.

[0030] Table 1 Volumes of Each Stage of the Steam Reciprocating Pump

[0031]

[0032] For the low-temperature dual-effect seawater desalination device adopting this design, under the condition of selecting the same operating conditions as the traditional low-temperature dual-effect seawater desalination device, the comparative analysis of the actual effects obtained and the effects of the traditional device is shown in Table 2.

[0033] Table 2 Comparative Analysis of the Actual Effects of the Traditional Device - Example 1

[0034]

[0035]

[0036] As can be seen from Table 2, compared with the traditional device, for the low-temperature dual-effect seawater desalination device using a steam reciprocating pump, the flow rate of motive steam is reduced by 37%, and the flow rate of cooling water is significantly reduced. Ideally, the flow rate of cooling seawater can be reduced to 0.

[0037] Example 2

[0038] The difference between this example and Example 1 is that the fresh water diversion chamber 5 is not included in the system. The first fresh water outlet of the first-effect evaporation chamber 1, the second product water outlet of the second-effect evaporation chamber 2, and the first product water outlet of the condenser 3 are connected to the product water pump 8 through pipelines. The fresh water generated in the first-effect evaporation chamber 1 directly converges with the fresh water generated in the second-effect evaporation chamber 2 and the fresh water generated in the condenser 3, and is discharged through the product water pump 8.

[0039] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A low-temperature multi-effect seawater desalination system using a steam reciprocating pump, comprising a multi-effect evaporator group, a condenser, a mixing chamber and a raw seawater pump, characterized in that, The low-temperature multi-effect seawater desalination system further includes a steam reciprocating pump module. The multi-effect evaporator group includes a plurality of serially connected evaporation chambers. The steam reciprocating pump module includes a plurality of serially connected steam reciprocating pumps. A part of the steam generated by the multi-effect evaporator group is used as suction steam and is transported to the steam reciprocating pump module. The suction steam is compressed and pressurized by motive steam in the steam reciprocating pump module to form new suction steam. The pressure of the motive steam is greater than that of the suction steam. The new suction steam and the new motive steam discharged from the steam reciprocating pump module are mixed in the mixing chamber to form heating steam. The heating steam enters the multi-effect evaporator group to cause the feed seawater to undergo phase change desalination. The remaining part of the steam generated by the multi-effect evaporator group is transported to the condenser. The raw seawater pumped by the raw seawater pump is heated in the condenser to become the feed seawater. The feed seawater is transported to the multi-effect evaporator group. The steam reciprocating pump includes a low-pressure cylinder and a high-pressure cylinder. The cross-sectional area of the high-pressure cylinder is smaller than that of the low-pressure cylinder. A low-pressure piston and a high-pressure piston are respectively arranged in the low-pressure cylinder and the high-pressure cylinder. The low-pressure piston and the high-pressure piston are connected by a piston rod. The low-pressure piston divides the low-pressure cylinder into a first low-pressure cylinder cavity and a second low-pressure cylinder cavity. The high-pressure piston divides the high-pressure cylinder into a first high-pressure cylinder cavity and a second high-pressure cylinder cavity. The first low-pressure cylinder cavity and the first high-pressure cylinder cavity are on the same side. A first low-pressure cylinder air port and a fourth low-pressure cylinder air port are respectively arranged on the left and right sides of the first low-pressure cylinder cavity. A second low-pressure cylinder air port and a third low-pressure cylinder air port are respectively arranged on the left and right sides of the second low-pressure cylinder cavity. A first high-pressure cylinder air port and a fourth high-pressure cylinder air port are respectively arranged on the left and right sides of the first high-pressure cylinder cavity. A second high-pressure cylinder air port and a third high-pressure cylinder air port are respectively arranged on the left and right sides of the second high-pressure cylinder cavity. Suction steam is pre-stored in both the first low-pressure cylinder cavity and the second low-pressure cylinder cavity. Motive steam is pre-stored in both the first high-pressure cylinder cavity and the second high-pressure cylinder cavity. Each air port is connected to a valve. The valve is a one-way valve, and the valve limits the pressure of the steam entering and leaving the air port. The motive steam enters the high-pressure cylinder of the first-stage steam reciprocating pump through the motive steam pipeline. The high-pressure cylinder of the last-stage steam reciprocating pump discharges new motive steam to the mixing chamber. The suction steam enters the low-pressure cylinder of each stage of the steam reciprocating pump. The low-pressure cylinder of each stage of the steam reciprocating pump discharges new suction steam to the mixing chamber to be mixed with the new motive steam.

2. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 1, wherein The low-temperature multi-effect seawater desalination system further includes a fresh water diversion chamber. A part of the fresh water generated by the multi-effect evaporator enters the fresh water diversion chamber for diversion. A part of the fresh water in the fresh water diversion chamber enters the boiler, and the remaining fresh water is discharged from the system.

3. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 2, characterized in that, The multi-effect evaporator group includes a serially connected first-effect evaporation chamber and second-effect evaporation chamber; the low-temperature multi-effect seawater desalination system further includes a concentrated brine pump, a product water pump and a fan. The concentrated brine pump is used to discharge the concentrated brine generated by the multi-effect evaporator group from the system. The product water pump is used to discharge the fresh water generated by the system from the system. The fan is used to transport the suction steam to the steam reciprocating pump module.

4. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 3, characterized in that, The first feed seawater inlet of the condenser is connected to the raw seawater pump. The feed seawater outlet of the condenser is connected to the second feed seawater inlet of the first-effect evaporation chamber and the third feed seawater inlet of the second-effect evaporation chamber through pipelines. The heating steam inlet of the first-effect evaporation chamber is connected to the heating steam outlet of the mixing chamber. The first-effect secondary steam outlet of the first-effect evaporation chamber is connected to the first-effect secondary steam inlet of the second-effect evaporation chamber. The first-effect concentrated brine outlet of the first-effect evaporation chamber is connected to the first-effect concentrated brine inlet of the second-effect evaporation chamber. The first-effect fresh water outlet of the first-effect evaporation chamber is connected to the inlet of the fresh water diversion chamber. The second-effect secondary steam outlet of the second-effect evaporation chamber is respectively connected to the second-effect secondary steam inlet of the condenser and the inlet of the fan. The concentrated brine outlet of the second-effect evaporation chamber is connected to the concentrated brine pump. The first outlet of the fresh water diversion chamber, the second product water outlet of the second-effect evaporation chamber and the first product water outlet of the condenser are connected in series through pipelines to the product water pump. The second outlet of the fresh water diversion chamber is connected to the boiler. The outlet of the fan is connected to the inlet pipeline of the steam reciprocating pump module. The power steam outlet pipeline of the steam reciprocating pump module is connected to the first inlet of the mixing chamber. The new suction steam pipeline of the steam reciprocating pump module is connected to the second inlet of the mixing chamber.

5. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 1, characterized in that, The valves in the steam reciprocating pump module are all solenoid valves, and the steam reciprocating pumps in the steam reciprocating pump module have the same structure.

6. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 1, characterized in that, The high-pressure cylinder port three is connected to the high-pressure cylinder port one of the next-stage steam reciprocating pump. The high-pressure cylinder port four is connected to the high-pressure cylinder port two of the next-stage steam reciprocating pump. The high-pressure cylinder port one and the high-pressure cylinder port two of the first-stage steam reciprocating pump are both connected to the power steam pipeline. The high-pressure cylinder port four and the high-pressure cylinder port three of the last-stage steam reciprocating pump are both connected to the new power steam pipeline. The low-pressure cylinder port one and the low-pressure cylinder port two of each stage of steam reciprocating pump are both connected to the suction steam pipeline. The low-pressure cylinder port three and the low-pressure cylinder port four of each stage of steam reciprocating pump are both connected to the new suction steam pipeline.

7. The low-temperature multi-effect seawater desalination system using a steam reciprocating pump according to claim 1, wherein The steam reciprocating pump module includes a series-connected first-stage steam reciprocating pump, second-stage steam reciprocating pump, third-stage steam reciprocating pump and fourth-stage steam reciprocating pump.

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