WO2008026354A1

WO2008026354A1 - Multistage flush type desalination plant

Info

Publication number: WO2008026354A1
Application number: PCT/JP2007/060328
Authority: WO
Inventors: Akira Shimizu
Original assignee: Hitachi Zosen Corporation
Priority date: 2006-08-29
Filing date: 2007-05-21
Publication date: 2008-03-06
Also published as: JP2008055244A; JP5105796B2

Abstract

A multistage flush type desalination plant which comprises: a heater (1) for brine; a first evaporator (2) which is a heat recovery part in which high-temperature brine heated with the heater is introduced, subjected to flush evaporation, and condensed with low-temperature brine for cooling to be supplied to the heater to thereby obtain fresh water; and a second evaporator (3) which is a heat dissipation part in which the brine discharged from the first evaporator (2) is introduced, subjected to flush evaporation, and condensed with seawater for cooling to thereby obtain fresh water, and the cooling seawater which has received the heat of condensation is discharged outside. The brine in the second evaporator (3) is supplied as cooling brine to the first evaporator. Part of the high-temperature brine introduced into the first evaporator (2) from the heater (1) is discharged outside as waste brine from the final stage in the first evaporator.

Description

Specification

Multi-stage flash water generator

Technical field

[0001] The present invention relates to a multi-stage flash type fresh water generator.

Background art

Seawater power As a device for obtaining fresh water, there is a multi-stage flash type fresh water generator.

[0003] As shown in Fig. 2, this fresh water generator is a flash evaporator that introduces a heating part (also called brine heater) 51 of salt water (also called brine) and high-temperature salt water heated by this heating part 51. And a heat recovery unit 52 that is condensed with low-temperature salt water for cooling supplied to the heating unit 51 to obtain fresh water (so-called fresh water), and the salt water from the heat recovery unit 52 is further guided and flushed. A heat release section 53 that evaporates and condenses with cooling seawater to obtain fresh water and discharges the seawater deprived of the condensation heat to the outside (outside of the system). The brine at the outlet of the discharge unit 53 is supplied as cooling brine for the heat recovery unit 52, and a part of the brine at the heat release unit 53 is taken out of the system from the final stage and discarded (for example, Kaisho 59-189985 See broadcast).

Disclosure of the invention

Problems to be solved by the invention

[0004] As described above, waste salt water (both blow-downs) is taken out from the final stage of the heat release unit (externally) and discarded. This is because the waste salt water is transmitted to the heat release unit. It is cooled by the seawater flowing in the heat pipe, and most of the seawater for cooling and waste saltwater are also discarded to the outside. There was a heat transfer load.

[0005] Accordingly, an object of the present invention is to provide a multi-stage flash type fresh water generator capable of reducing a heat transfer load in a heat release portion.

Means for solving the problem

[0006] In order to solve the above problems, a multistage flash type fresh water generator of the present invention guides and evaporates salt water heated by a salt water heating unit and the salt water heated by the heating unit and supplies the salt to the heating unit. The heat recovery unit that condenses with the supplied salt water to obtain fresh water, and further directs the salt water from the heat recovery unit to flash evaporate and condense with cooling seawater to obtain fresh water and the condensation. And a heat release part that discharges the seawater for cooling that has been deprived of heat to the outside of the system, and the salt water in the heat release part is supplied to the heat recovery part as salt water for cooling. Multi-stage flash water generator

A part of the salt water led from the heating unit to the final stage of the heat recovery unit or the previous stage of the heat release unit is discharged out of the system.

[0007] Further, another multi-stage flash type fresh water generator of the present invention includes a heater that heats salt water, and salt water heated by the heater to perform flash evaporation and salt water flowing in a heat transfer tube. Condensed by the first evaporator with multiple stages of evaporation chambers to condense and obtain fresh water, and the salt water of this first evaporator power is further led to flash evaporation and cooling seawater flowing in the heat transfer tube A second evaporator provided with a plurality of stages of evaporation chambers for obtaining fresh water, a seawater supply pipe for supplying seawater for cooling to the heat transfer pipes in the final stage evaporation chamber of the second evaporator, and the second A fresh water extraction pipe for taking fresh water from the final stage evaporation chamber of the evaporator, a sea water discharge pipe for discharging cooling seawater from the heat transfer pipe in the first stage evaporation chamber of the second evaporator, and the sea water discharge pipe A part of the seawater in this second evaporator Seawater replenishment line for supplying water back into the final stage evaporation chamber, and salt water circulation supply for supplying salt water in the second evaporator to the heat transfer pipe in the final stage evaporation chamber of the first evaporator as cooling salt water A multistage flash type water freshener having a conduit,

It is equipped with a waste saltwater discharge pipe that discharges part of the saltwater in the final stage evaporation chamber of the first evaporator to the outside of the system.

[0008] Further, another multi-stage flash type fresh water generator of the present invention includes a heater that heats salt water, and salt water heated by the heater to perform flash evaporation and salt water flowing in the heat transfer tube. The first evaporator is provided with multiple stages of evaporation chambers that are condensed to obtain fresh water, and the salt water of this first evaporator power is further guided to perform flash evaporation and to be condensed by cooling seawater flowing in the heat transfer tubes A second evaporator provided with a plurality of stages of evaporation chambers for obtaining fresh water, a seawater supply pipe for supplying seawater for cooling to the heat transfer tubes in the final stage evaporation chamber of the second evaporator, and the second (2) Fresh water removal to remove fresh water from the final stage evaporation chamber of the evaporator The outlet pipe, the heat transfer pipe in the first stage evaporation chamber of the second evaporator, the seawater discharge pipe for discharging the seawater for cooling out of the system, and part of the seawater in the seawater discharge pipe A seawater replenishment line for supplying water back into the final stage evaporation chamber of the evaporator, and a salt water circulation supply for supplying salt water in the second evaporator to the heat transfer pipe in the final stage evaporation chamber of the first evaporator as cooling water A multistage flash type water freshener having a conduit,

A waste salt water discharge pipe for discharging a part of the salt water in the front stage evaporation chamber before the final stage of the second evaporator to the outside of the system is provided.

The invention's effect

[0009] According to the above configuration, a part of the salt water is transferred to the second evaporator, which is the heat release unit, and the remaining part is the final stage of the first evaporator, which is the heat recovery unit, or the front stage side of the second evaporator. As compared with the conventional case where everything is transferred to the heat release part, lowered to a predetermined temperature and discharged outside the power system, as in the conventional case, the heat release part is discharged from the system. The heat transfer area can be reduced, in other words, the heat transfer load can be reduced, and therefore the amount of heat transfer tubes made of expensive materials such as titanium can be reduced. Can be achieved.

[0010] Further, since the amount of the seawater for cooling supplied to the heat release part can be reduced, it is possible to reduce the power in the seawater intake facility and to further reduce the manufacturing cost. it can.

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic pipeline system of a multi-stage flash type fresh water generator according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic pipeline system of a multistage flash type fresh water generator according to a conventional example. BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a multi-stage flash type fresh water generator according to an embodiment of the present invention will be described with reference to FIG.

[0013] This multi-stage flash type fresh water generator has a heater (an example of a heating unit) 1 that heats salt water (also referred to as brine) with steam, and a high-temperature salt water heated by the heater 1 for flashing. Evaporates and condenses with low-temperature salt water for cooling that flows in the heat transfer tube 12 to produce fresh water The first evaporator (an example of the heat recovery unit) 2 in which the evaporation chamber 11 having a plurality of stages (for example, 16 stages) 2 is formed, and the salt water from the first evaporator 2 is further guided to perform flash evaporation. A second evaporator (heat release part) in which an evaporation chamber 16 is obtained in a plurality of stages (for example, three stages) to obtain fresh water (so-called fresh water) by condensing with cooling seawater flowing in the heat transfer pipe 17. 3) and a vacuum device 4 for sucking the air in each of the evaporation chambers 11 and 16 of each of the evaporators 2 and 3 so as to reduce the pressure to a predetermined pressure or less. In each of the evaporation chambers 11 and 16, trays 13 and 18 for collecting condensed fresh water are respectively arranged. “Sea water” and “salt water” are used separately, but “salt water” indicates that the seawater is heated to evaporate the water and the salt concentration becomes high.

[0014] As a piping system of the fresh water generator, a seawater supply pipe (seawater supply pipe) 21 for supplying seawater for cooling to the heat transfer pipe 17 of the final stage evaporation chamber 16 (16C) of the second evaporator 3 and A fresh water take-out pipe (fresh water take-out pipe) 22 for taking fresh water from the tray 18 of the final stage evaporation chamber 16C of the second evaporator 3 and a first stage evaporation chamber (both the previous stage evaporation chamber!) Of the second evaporator 3! ) A seawater discharge pipe (seawater discharge pipe) 23 that discharges cooling seawater from the heat transfer pipe 17 in 16 (16A) to the outside (outside the system) and a part of the cooling seawater in the seawater discharge pipe 23 A seawater supply pipe (seawater supply pipe) 24 for supplying seawater back to the final stage evaporation chamber 16C of the second evaporator 3 and (more specifically, the final stage evaporation in the second evaporator 3). Salt water that circulates salt water (in chamber 16C) as low-temperature salt water (also called circulating brine) for cooling to the heat transfer pipe 12 in the final stage evaporation chamber 11 (I IP) of the first evaporator 2 Low-temperature salt water that transfers low-temperature salt water for cooling from the ring supply pipe (salt water circulation supply pipe) 25 and the heat transfer pipe 12 in the first stage evaporation chamber 11 (11A) of the first evaporator 2 to the heater 1 Transfer pipe 26, high-temperature salt water transfer pipe 27 for transferring the high-temperature salt water heated by the heater 1 to the first stage evaporation chamber 11A of the first evaporator 2, and the last stage evaporation chamber 11P of the first evaporator 2 And a waste saltwater discharge pipe (waste saltwater discharge pipe) 28 for discharging (discarding) the saltwater to the outside (outside). Of the three-stage evaporation chambers 16 of the second evaporator 3, the central evaporation chamber is called the middle-stage evaporation chamber 16 (16B), and the evaporation chamber on the front side of the final stage, that is, the first-stage evaporation chamber 16A and the intermediate-stage evaporation chamber. Chamber 16B is collectively referred to as the pre-stage evaporation chamber.

[0015] Further, the upper portions of the evaporation chambers 11, 11; 16, 16 in each of the evaporators 2, 3 are communicated with each other via a vapor communication portion (not shown, for example, a communication pipe), and the evaporation chamber 11 , 11; 16, 16 are connected to each other through, for example, salt water communication portions 11a, 16a having orifices, and the fresh water in each of the trays 13, 18 is supplied to the first stage evaporation chamber of the first evaporator 2. Move sequentially from 11 A pan 13 to the final stage evaporation chamber 16 C of the second evaporator 3 to the pan 18 of the second evaporator 3, and connect with pipes so that they can be taken out from the fresh water discharge pipe 22!

[0016] Furthermore, the first evaporator 2 and the second evaporator 3 are actually configured integrally, so that the second evaporator in the final stage evaporation chamber I IP of the first evaporator 2 and the second evaporator. The inside of the first stage evaporation chamber 16A of the vessel 3 is communicated with each other at the vapor communication portion P1 in the same manner as the vapor communication portion between the respective evaporation chambers, and similarly to the salt water communication portions 11a, 16a between the respective evaporation chambers. They are connected to each other at the saltwater communication part P2.

Note that a steam supply pipe 31 for supplying heating steam is connected to the heater 1, and a drain discharge pipe 32 for taking out the drain generated in the heater 1 is connected.

[0018] Each pipe is provided with a pump 41 for transferring seawater, salt water, fresh water, drain, and the like as necessary.

[0019] Furthermore, the vacuum device 4 extracts the air that has flowed into the evaporation chambers 11 and 16 and the air dissolved in the supplementary seawater, and maintains the evaporation chambers 11 and 16 at a predetermined degree of vacuum. Specifically, a steam-driven ejector is used. The air and steam taken out by the ejector are cooled by the cooling seawater supplied from the condensing seawater supply pipe 43 by the condenser 42.

[0020] The operation of obtaining fresh water by the fresh water generator will be described.

[0021] Steam is supplied to the heater 1 and supplied to the second evaporator 3 from the seawater supply pipe 21 in a state where the inside of each of the evaporation chambers 11 and 16 is maintained at a predetermined pressure by the vacuum device 4. The seawater for cooling (for example, about 35 ° C.) sequentially passes through the heat transfer pipes 17 in the respective evaporation chambers 16, and a part of the seawater is supplied into the second evaporator 3 through the seawater supply pipes 24. The salt water (circulation brine) in the second evaporator 3 is sequentially passed through the heat transfer pipes 12 in the respective evaporation chambers 11 of the first evaporator 2 through the salt water circulation supply pipe 25 to be heated. It is transferred to 1 where it is heated to a certain temperature (eg, around 105 ° C) by steam.

[0022] The heated high-temperature salt water is transferred into the first stage evaporation chamber 11A of the first evaporator 2 and evaporated under reduced pressure (so-called flash evaporation), and the evaporated vapor is transferred into the heat transfer tube 12. Flow It is cooled by the low-temperature salt water for cooling, condenses into fresh water, and falls onto the tray 13.

[0023] In addition, the salt water that has entered the evaporation chamber 11 of the next stage via the salt water communication part 11a is also flash evaporated and condensed in the heat transfer tube 12 to become fresh water, and falls on the tray 13 .

As described above, the high-temperature salt water from the heater 1 is sequentially moved from the first stage evaporation chamber 11A of the first evaporator 2 to the last stage evaporation chamber IIP.

In the second evaporator 3, as in the first evaporator 2, the second evaporator 3 moves from the first stage evaporation chamber 16 A to the last stage evaporation chamber 16 C and flows in the heat transfer tubes 17 in the respective evaporation chambers 16. It is condensed by the seawater for cooling to obtain fresh water, which falls on the tray 18 each. The fresh water obtained by these evaporators 2 and 3 is finally taken out from the fresh water discharge pipe 22.

[0026] By the way, the high-temperature salt water supplied from the heater 1 to the bottom of the first evaporator 2 sequentially moves from the first stage evaporation chamber 11A to the last stage evaporation chamber I IP, and then to the salt water communication section P1. Is transferred to the second evaporator 3 through the first evaporator 2, but part of it is discharged from the final stage evaporation chamber I IP of the first evaporator 2 to the outside (external) via the waste saltwater discharge pipe 28. Is done.

[0027] The salt water transferred into the second evaporator 3 passes through the salt water circulation supply pipe 25 to the heat transfer pipe 12 in the final stage evaporation chamber I IP of the first evaporator 2 as cooling salt water. Supplied.

[0028] As described above, a part of the salt water transferred (supplied) from the heater 1 to the first evaporator 2 is discharged from the final stage evaporation chamber I IP of the first evaporator 2 to the outside. For example, compared with the case where the second evaporator 3 is transferred to the second evaporator 3 and discharged from the final stage evaporation chamber 16C of the second evaporator 3, the amount of cooling heat in the second evaporator 3 (with the heat transfer load). There is less).

More specifically, when the temperature of salt water transferred from the second evaporator 3 to the heat transfer tube 12 of the first evaporator 2 is high, the condensation efficiency in the first evaporator 2, that is, the generation efficiency of fresh water. Therefore, it is necessary to lower the salt water temperature in the second evaporator 3 to some extent (for example, 43 ° C). Therefore, the amount of flash evaporation is reduced by the amount of salt water transferred from the first evaporator 2 to the second evaporator 3, and the heat transfer area in the second evaporator 3 can be reduced.

[0030] That is, the amount of the heat transfer tube 17 that is arranged in the second evaporator 3 and made of an expensive material such as titanium can be reduced, and accordingly, the manufacturing cost of the equipment is reduced. [0031] Further, since the amount of cooling seawater supplied to the second evaporator 3 can be reduced, the power of the seawater intake facility can be reduced, and the production cost of the seawater intake facility can be reduced. Reduction can be achieved.

[0032] Here, for the apparatus according to the present invention and the apparatus corresponding to the conventional example, the results of comparing the heat transfer area in each part, and the temperature and flow rate of seawater, salt water, and fresh water are shown in the following [Table 1]. ].

[0033] [Table 1]

[0034] It should be noted that the number of the pipe member through which each fluid flows (the member number of the pipe) is entered in the column of the pipe position in [Table 1].

[0035] As shown in this [Table 1] force component, the heat transfer area in the second evaporator 3 as the heat release part is reduced by about 15% compared to the conventional device, and the seawater supply It can be seen that the amount of seawater supplied from pipe 21 has also decreased by about 15%. For Shimizu, the decrease is as small as 1.6%, and there is almost no problem.

Incidentally, in the above embodiment, it has been described that part of the salt water is discharged from the final stage evaporation chamber I IP of the first evaporator 2 to the outside of the system, but the final stage evaporation chamber of the second evaporator 3 is described. A part of salt water may be discharged from the front side other than 16C, that is, from the first stage evaporation chamber 16A or the middle stage evaporation chamber 16B. In this case as well, the heat transfer load in the second evaporator 3 can be reduced (however, the rate of reduction of the heat transfer load is slightly lower than in the above-described embodiment).

Claims

The scope of the claims

[1] A salt water heating section, a heat recovery section that guides the salt water heated by the heating section, flashes and evaporates it, and condenses the salt water supplied to the heating section to obtain fresh water, and this heat recovery section. A heat release unit that further directs the salt water of the partial strength, flashes and evaporates it, condenses it with cooling seawater to obtain fresh water, and discharges the cooling seawater that has deprived the heat of condensation out of the system. In the multi-stage flash type fresh water generator that further supplies the salt water in the heat release part to the heat recovery part as cooling salt water, the heat recovery part is connected to the final stage of the heat recovery part or the heat release part. A multi-stage flash type fresh water generator, characterized in that a part of the salt water led to the front stage from the last stage is discharged out of the system.

[2] a heater for heating salt water;

A first evaporator provided with a plurality of evaporating chambers for providing fresh water by guiding the salt water heated by the heater to perform flash evaporation and condensing with salt water flowing in the heat transfer pipe;

A second evaporator provided with a plurality of stages of evaporating chambers for obtaining fresh water by further guiding the salt water of the first evaporator force to perform flash evaporation and condensing with cooling seawater flowing in the heat transfer pipe;

A seawater supply line for supplying cooling seawater to the heat transfer pipe in the final stage evaporation chamber of the second evaporator, a fresh water extraction line for taking fresh water from the final stage evaporation chamber of the second evaporator, and the second evaporation Heat transfer pipe force in the first stage evaporation chamber of the evaporator Seawater discharge pipe that discharges the seawater for cooling out of the system and a part of the seawater in the seawater discharge pipe is returned to the final stage evaporation room of the second evaporator. A seawater supply line for replenishment;

A multi-stage flash type fresh water generator having a salt water circulation supply pipe for supplying salt water in the second evaporator to a heat transfer pipe in the final stage evaporation chamber of the first evaporator as cooling salt water. A multi-stage flash type fresh water generator having a waste salt water discharge pipe for discharging a part of salt water in the final stage evaporation chamber of one evaporator out of the system.

[3] a heater for heating salt water;

The salt water heated by this heater is guided to perform flash evaporation and flow through the heat transfer tubes. A first evaporator provided with a plurality of stages of evaporation chambers for condensing with salt water to obtain fresh water;

A multi-stage flash type fresh water generator having a salt water circulation supply pipe for supplying salt water in the second evaporator to a heat transfer pipe in the final stage evaporation chamber of the first evaporator as cooling salt water. (2) A multi-stage flash type fresh water generator having a waste salt water discharge pipe for discharging a part of salt water in the front evaporation chamber before the final stage of the evaporator to the outside of the system.