CN216837200U - A low-temperature multi-effect evaporation seawater desalination energy utilization system - Google Patents

Abstract

The utility model discloses a seawater desalination energy utilization system with low-temperature multi-effect evaporation, which comprises n-stage evaporation units which are connected in series in sequence, wherein n is more than or equal to 3; each stage of evaporation unit comprises an evaporator and a flash tank, each stage of evaporation unit from 1 to n-1 further comprises a preheater, each stage of evaporation unit further comprises a condenser (8), a steam inlet of the evaporator D1-Dn is communicated with a steam supply pipeline, and a condensate outlet of the evaporator D1-Dn is communicated with a fresh water pipeline; the seawater inlet of the preheater E1-E (n-1) is communicated with a seawater pipeline, and the seawater outlet of the preheater E1 is communicated with the seawater inlet of the evaporator D1; concentrated seawater outlets of the evaporators D1-Dn are communicated with seawater inlets of the flash tanks V1-Vn, and seawater outlets of the flash tanks V1-V (n-1) are respectively communicated with seawater inlets of the evaporators D2-Dn in the next stage of evaporation unit. The utility model discloses the sensible heat and the latent heat of make full use of secondary steam and evaporimeter condensate reduce the system energy consumption, optimize process flow, improve the system and make water performance.

Description

A low-temperature multi-effect evaporation seawater desalination energy utilization system

technical field

The utility model relates to a low-temperature multi-effect evaporation seawater desalination energy utilization system, which belongs to the technical field of seawater evaporation and desalination.

Background technique

Desalination is the use of seawater desalination to produce fresh water. It is an open source incremental technology to realize the utilization of water resources, which can increase the total amount of fresh water, and is not affected by time, space and climate, and can ensure stable water supply such as drinking water for coastal residents and industrial boiler replenishment. The process of obtaining fresh water from sea water is called desalination. The seawater desalination methods currently used include seawater freezing method, electrodialysis method, distillation method, reverse osmosis method, and ammonium carbonate ion exchange method. At present, the application of reverse osmosis membrane method and distillation method is the mainstream in the market. There are more than 100 scientific research institutions in more than 10 countries in the world carrying out research on desalination, and there are hundreds of desalination facilities with different structures and different capacities. A modern large-scale desalination plant can produce thousands, tens of thousands or even nearly one million tons of fresh water every day. How to produce fresh water from seawater at low cost has become an urgent technical problem to be solved.

Utility model content

The purpose of this utility model is to provide a low-temperature multi-effect evaporation seawater desalination energy utilization system, making full use of the sensible heat and latent heat of secondary steam and evaporator condensate, reducing system energy consumption, optimizing process flow, and improving system water production. performance.

In order to solve the above-mentioned technical problems, the utility model adopts the following technical solutions:

A low-temperature multi-effect evaporation seawater desalination energy utilization system, comprising n-stage evaporation units connected in series in sequence, n≥3; each stage of evaporation unit includes an evaporator and a flash tank, and the 1 to n-1 stage evaporation units also include a preheater. Heater, the n-stage evaporation unit also includes a condenser, the steam inlet of the evaporator D1 is connected to the steam supply pipeline, the condensed water outlets of the evaporators D1-Dn are connected to the fresh water pipeline; the seawater inlet of the preheater E(n-1) is connected It is connected to the seawater pipeline, the seawater outlet of the preheater E(n-1) is connected to the seawater inlet of the preheater E(n-2), and the seawater outlet of the preheater E1 is connected to the seawater inlet of the evaporator D1; the evaporator D1- The concentrated seawater outlets of Dn are respectively connected to the seawater inlets of the flash tanks V1-Vn, and the seawater outlets of the flash tanks V1-V(n-1) are respectively connected to the seawater inlets of the evaporators D2-Dn in the next-stage evaporation unit; The secondary steam outlets of D1-D(n-1) are respectively connected to the steam inlets of the preheaters E1-E(n-1), and are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit. The steam outlets of the evaporators E1-E(n-1) are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit; the steam outlets of the flash tanks V1-V(n-1) are respectively connected to the preheaters E1- The steam inlets of E(n-1) are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit.

The 1-(n-1) stage evaporation unit evaporates and desalinates seawater by the following methods: after the steam in the steam supply pipeline enters the evaporator D1, the seawater in the evaporator D1 is heated, and the water discharged from the evaporator D1 is heated. Part of the secondary steam enters the evaporator D2, and the other part enters the preheater E1. The preheater E1 preheats the seawater, and the steam discharged from the preheater E1 enters the evaporator D2 of the next-stage evaporation unit; the evaporator D1 will concentrate the water. The seawater is discharged into the flash tank V1, and the flash steam generated by the flash tank V1 is supplied to the preheater E1 and the evaporator D2 of the next-stage evaporation unit; Evaporation and desalination.

In the foregoing seawater desalination energy utilization system of low-temperature multi-effect evaporation, the water outlet of the flash tank Vn is connected to the concentrated seawater pipeline; the secondary steam outlet of the evaporator Dn and the steam outlet of the flash tank Vn are all connected to the condenser. Steam inlet.

The n-th stage evaporation unit evaporates and desalinates seawater by the following methods: the secondary steam of the evaporator D(n-1) of the n-1 stage evaporation unit, and the steam discharged from the preheater E(n-1) And the flash steam output from the flash tank V(n-1) leads to the steam inlet of the evaporator Dn, the evaporator Dn evaporates the seawater, the fresh water produced by the evaporator Dn leads to the fresh water pipeline, and the concentrated seawater produced by the evaporator Dn It leads to the flash tank Vn, and the concentrated seawater produced by the flash tank Vn leads to the concentrated seawater pipeline; part of the secondary steam of the evaporator Dn leads to the condenser, through which the feed seawater is heated for the first time; The other part of the secondary steam leads to the steam supply pipeline, and is used for the next round with the driving steam; part of the flash steam output from the flash tank Vn leads to the condenser, and the other part leads to the steam supply pipeline.

In the aforementioned low-temperature multi-effect evaporation seawater desalination energy utilization system, the condensed water outlet of the condenser is connected to the fresh water pipeline; the water inlet of the condenser is connected to the feeding seawater pipeline, and one water outlet of the condenser is connected to the seawater pipeline , and the other water outlet is connected to the cooling seawater discharge pipe.

In the aforementioned low-temperature multi-effect evaporation seawater desalination energy utilization system, the steam supply pipeline is provided with a steam ejector TVC, the secondary steam outlet of the evaporator Dn is connected to the steam inlet of the steam ejector TVC, and the The steam outlet of the flash tank Vn communicates with the steam inlet of the steam ejector TVC.

In the above-mentioned low-temperature multi-effect evaporation seawater desalination energy utilization system, the number of stages of the evaporation units is n≥4.

Compared with the prior art, the utility model makes full use of the sensible heat and latent heat of the secondary steam and the condensate of the evaporator, reduces the energy consumption of the system, optimizes the technological process, and improves the water-making performance of the system. In order to achieve the purpose of reducing consumption and increasing efficiency, in addition to the utilization of secondary steam, the utilization of the heat of the evaporator condensate is also considered. The condensate discharged from the evaporator can recover latent heat by self-evaporation. Since the saturation temperature of the condensed water decreases as the pressure decreases, the condensed water with a higher temperature in the previous effect can be decompressed to the pressure of the next effect, and the condensate will generate steam in the process, and this part of the steam can be mixed with the second effect. The secondary steam is used as the heating steam for the next effect.

The low temperature multi-effect evaporative seawater desalination technology (LT-MED) is adopted to slow down the corrosion of equipment and the scaling of inorganic salts. LT-MED requires external heating steam to heat and evaporate the seawater in the first-effect evaporator. Compared with the low-grade steam produced by the steam turbine unit of the thermal power plant, the heating steam required by LT-MED is much lower. Effectively utilize the power and heat of high-grade steam, and introduce the thermal compressor TVC into the LT-MED unit to form a TVC-LT-MED seawater desalination unit. TVC is driven by high-pressure steam, injects part of the secondary steam of the final-effect evaporator, and mixes it together as the heating steam of the first-effect evaporator, which not only improves the utilization rate of the heat of the secondary steam, but also reduces the heat of the condenser. load.

At present, the low-temperature multi-effect evaporation seawater desalination technology (LT-MED) mostly adopts the co-current feeding method. Compared with advection and counter-current, it has the following significant advantages: 1. Anti-scaling: in the process flow, the first-effect evaporator has low salt , the end-effect evaporator has low temperature and high salt, that is, the concentrated seawater with high salt content is in a lower temperature area, which is conducive to avoiding the precipitation of calcium sulfate crystallization and reducing scaling, so the downstream process has the best scaling resistance; 2. Power saving: the operating pressure of each effect evaporator is gradually reduced, the material seawater does not need to be transported by a pump, and can flow into the latter effect evaporator by itself by the pressure difference between the effects, saving pump work; 3. Improve the water production ratio: although the material The continuous evaporation of seawater will gradually increase the concentration, resulting in an increase in the boiling point, but the increase in the boiling point caused by the concentration change is far less than the effect of the pressure difference between the effects. Therefore, flash evaporation occurs when the material flows between the effects. Thereby improving the water-making performance.

Description of drawings

FIG. 1 is a schematic diagram of a system structure according to an embodiment of the present invention.

Reference numerals: 1-steam supply line, 2-seawater line, 3-fresh water line, 4-evaporator D1, 5-preheater E1, 6-evaporator D2, 7-steam ejector TVC, 8 - Condenser, 9 - Flash Tank V1.

The present utility model will be further described below with reference to the accompanying drawings and specific embodiments.

Detailed ways

Embodiment 1 of the present utility model: a low-temperature multi-effect evaporation seawater desalination energy utilization system, comprising n-stage evaporation units connected in series in sequence, n≥3; each level of evaporation unit includes an evaporator and a flash tank, 1 to n -The first-stage evaporation unit further includes a preheater, and the n-stage evaporation unit further includes a condenser 8, the steam inlet of the evaporator D14 is connected to the steam supply pipeline 1, and the condensed water outlet of the evaporators D1-Dn is connected to the fresh water pipeline 3; The seawater inlet of the preheater E(n-1) is connected to the seawater pipeline 2, the seawater outlet of the preheater E(n-1) is connected to the seawater inlet of the preheater E(n-2), and the The seawater outlet is connected to the seawater inlet of the evaporator D14; the concentrated seawater outlet of the evaporator D1-Dn is respectively connected to the seawater inlet of the flash tank V1-Vn, and the seawater outlet of the flash tank V1-V(n-1) is respectively connected to the next The seawater inlets of the evaporators D2-Dn in the stage evaporation unit; the secondary steam outlets of the evaporators D1-D(n-1) are respectively connected to the steam inlets of the preheaters E1-E(n-1), and are respectively connected to the next The steam inlets of evaporators D2-Dn in the first-stage evaporation unit, and the steam outlets of the preheaters E1-E(n-1) are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit; flash tanks V1-V The steam outlets of (n-1) are respectively connected to the steam inlets of the preheaters E1-E(n-1), and are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit.

Embodiment 2: A low-temperature multi-effect evaporation seawater desalination energy utilization system, including n-stage evaporation units connected in series, n≥3; each stage of evaporation unit includes an evaporator and a flash tank, and 1 to n-1 stages of evaporation The unit also includes a preheater, the n-stage evaporation unit also includes a condenser 8, the steam inlet of the evaporator D14 is connected to the steam supply line 1, and the condensed water outlet of the evaporators D1-Dn is connected to the fresh water line 3; the preheater E The seawater inlet of (n-1) is connected to the seawater pipeline 2, the seawater outlet of the preheater E(n-1) is connected to the seawater inlet of the preheater E(n-2), and the seawater outlet of the preheater E15 is connected to the evaporation The seawater inlets of the evaporators D1-Dn are respectively connected to the seawater inlets of the flash tanks V1-Vn, and the seawater outlets of the flash tanks V1-V(n-1) are respectively connected to the next-stage evaporation unit. The seawater inlets of the evaporators D2-Dn; the secondary steam outlets of the evaporators D1-D(n-1) are respectively connected to the steam inlets of the preheaters E1-E(n-1), and are respectively connected to the next-stage evaporation unit The steam inlets of the evaporators D2-Dn and the steam outlets of the preheaters E1-E(n-1) are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit; the flash tanks V1-V(n-1 ) of the steam outlets are respectively connected to the steam inlets of the preheaters E1-E(n-1), and are respectively connected to the steam inlets of the evaporators D2-Dn in the next-stage evaporation unit; the water outlet of the flash tank Vn is connected to the concentrated seawater pipe Road; the secondary steam outlet of the evaporator Dn and the steam outlet of the flash tank Vn are all connected to the steam inlet of the condenser 8 .

Embodiment 3: As shown in Figure 1, a low-temperature multi-effect evaporation seawater desalination energy utilization system includes n-stage evaporation units connected in series in sequence, in this embodiment n=4; each stage of evaporation units includes an evaporator and Flash tank, the 1st to 3rd stage evaporation units also include a preheater, the 4th stage evaporation unit also includes a condenser 8, the steam inlet of the evaporator D14 is connected to the steam supply line 1, and the condensed water outlet of the evaporators D1-D4 is connected to Fresh water pipeline 3; the seawater inlet of preheater E3 is connected to seawater pipeline 2, the seawater outlet of preheater E3 is connected to the seawater inlet of preheater E2, and the seawater outlet of preheater E15 is connected to the seawater inlet of evaporator D14 ; The concentrated seawater outlets of evaporators D1-D4 are respectively connected to the seawater inlets of flash tanks V1-V4, and the seawater outlets of flash tanks V1-V3 are respectively connected to the seawater inlets of evaporators D2-D4 in the next-stage evaporation unit; The secondary steam outlets of D1-D3 are respectively connected to the steam inlets of the preheaters E1-E3, and are respectively connected to the steam inlets of the evaporators D2-D4 in the next-stage evaporation unit, and the steam outlets of the preheaters E1-E3 are respectively connected to the lower The steam inlets of the evaporators D2-D4 in the first-stage evaporation unit; the steam outlets of the flash tanks V1-V3 are respectively connected with the steam inlets of the preheaters E1-E3, and are respectively connected with the steam inlets of the evaporators D2-D4 in the next-stage evaporation unit. The steam inlet; the water outlet of the flash tank V4 is connected to the concentrated seawater pipeline; the secondary steam outlet of the evaporator D4 and the steam outlet of the flash tank V4 are all connected to the steam inlet of the condenser 8; the condensed water outlet of the condenser 8 The fresh water pipeline 3 is connected; the water inlet of the condenser 8 is connected to the feeding seawater pipeline, one water outlet of the condenser 8 is connected to the seawater pipeline 2, and the other water outlet is connected to the cooling seawater discharge pipe; There is a steam ejector TVC 7 , the secondary steam outlet of the evaporator D4 communicates with the steam inlet of the steam ejector TVC 7 , and the steam outlet of the flash tank V4 communicates with the steam inlet of the steam ejector TVC 7 .

The working principle of the preferred solution of the present invention: the seawater first enters the preheater E(n-1)-E1 for preheating, and then enters the evaporator D1, and steam is introduced into the evaporator D1 to heat and evaporate the seawater, and the evaporator D1 produces The concentrated seawater that comes out enters the flash tank V1 for self-evaporation, then enters the evaporator D2 for evaporation, and then enters the flash tank V2 for self-evaporation, until Dn, Vn, and the condensed water produced by the evaporators D1-Dn enters the fresh water pipeline. 3; The residual liquid produced by Vn is discharged in the form of concentrated seawater; a part of the secondary steam produced by the evaporator D1-D(n-1) is introduced into the corresponding preheater E1-E(n-1), and the other part enters the next effect evaporator D2-Dn, part of the flash steam discharged from the flash tank V1-V(n-1) is introduced into the corresponding preheater E1-E(n-1), and the other part enters the next effect evaporator D2-Dn, The steam discharged from the preheater E1-E(n-1) enters the evaporators D2-Dn of the next-stage evaporation unit, and the secondary steam produced by the evaporator Dn and the flash steam discharged from the flash tank Vn both enter the condenser 8 The feed seawater is preheated by the condenser 8, and part of it is discharged in the form of cooling seawater, and the other part enters the preheater E (n-1) through the seawater pipeline 2; the condensed water discharged from the condenser 8 enters the fresh water Pipeline 3; the steam injector TVC 7 on the steam supply line 1 is driven by high-pressure steam, and introduces part of the secondary steam of the evaporator Dn and part of the flash steam of the flash tank Vn, and mixed together as the first effect evaporator D1 heating steam.

The system adopts the multi-effect treatment method, adopts the multi-stage evaporation unit in series to utilize the heat of the steam step by step, and the steam generated during the seawater evaporation process is also incorporated into the driving steam for recycling, which can utilize the heat of the driving steam more efficiently. , to improve the water-making performance of the system. The preheaters of the evaporation units at all levels are arranged in series, which can preheat the seawater to about 70 degrees Celsius.

Claims (5)

1. a seawater desalination energy utilization system of low-temperature multi-effect evaporation, is characterized in that, comprises n-level evaporation units connected in series successively, n≥3; Each level of evaporation unit comprises evaporator and flash tank, 1 to n-1 The first-stage evaporation unit further includes a preheater, the n-stage evaporation unit further includes a condenser (8), the steam inlet of the evaporator D1 (4) is connected to the steam supply pipeline (1), and the condensed water outlets of the evaporators D1-Dn are connected to fresh water The pipeline (3); the seawater inlet of the preheater E(n-1) is connected to the seawater pipeline (2), and the seawater outlet of the preheater E(n-1) is connected to the seawater of the preheater E(n-2). Inlet, the seawater outlet of the preheater E1(5) is connected to the seawater inlet of the evaporator D1(4); the concentrated seawater outlets of the evaporators D1-Dn are respectively connected to the seawater inlets of the flash tanks V1-Vn, and the flash tanks V1-V The seawater outlets of (n-1) are respectively connected to the seawater inlets of the evaporators D2-Dn in the next-stage evaporation unit; the secondary steam outlets of the evaporators D1-D(n-1) are respectively connected to the preheaters E1-E(n The steam inlet of -1) is connected to the steam inlet of the evaporator D2-Dn in the next-stage evaporation unit respectively, and the steam outlet of the preheater E1-E(n-1) is respectively connected to the evaporator D2 in the next-stage evaporation unit The steam inlet of -Dn; the steam outlet of the flash tank V1-V(n-1) is respectively connected to the steam inlet of the preheater E1-E(n-1), and is respectively connected to the evaporator D2- Dn steam inlet. 2. the seawater desalination energy utilization system of a kind of low-temperature multi-effect evaporation according to claim 1, is characterized in that, the water outlet of flash tank Vn communicates with thick seawater pipeline; The secondary steam outlet of evaporator Dn, flash evaporation The steam outlets of the tank Vn are all connected to the steam inlet of the condenser (8). 3. The seawater desalination energy utilization system of a low-temperature multi-effect evaporation according to claim 2, wherein the condensed water outlet of the condenser (8) is communicated with a fresh water pipeline (3); the condenser (8) The water inlet of the condenser (8) is connected to the feeding seawater pipe, one water outlet of the condenser (8) is connected to the seawater pipeline (2), and the other water outlet is connected to the cooling seawater discharge pipe. 4. The seawater desalination energy utilization system of a low-temperature multi-effect evaporation according to claim 3, wherein the steam supply pipeline (1) is provided with a steam ejector TVC (7), and the evaporator is provided with a steam ejector TVC (7). The secondary steam outlet of Dn communicates with the steam inlet of the steam ejector TVC(7), and the steam outlet of the flash tank Vn communicates with the steam inlet of the steam ejector TVC(7). 5 . The seawater desalination energy utilization system of low-temperature multi-effect evaporation according to claim 4 , wherein the number of stages of the evaporation units is n≧4. 6 .

Images