CN207435085U - Minimize positive pressure distillation seawater desalination system - Google Patents

Abstract

The purpose of this utility model is to provide a miniaturized positive pressure distillation seawater desalination system, which includes a feedwater preheater, a feedwater pump, an evaporator, a steam-water separator, a condenser, and a condensate pump. The heat exchange tube, the water outlet of the feed water preheater is connected to the heat exchange component in the evaporator through the feed water pump, the inlet of the steam-water separator is installed at the steam outlet of the evaporator, and the outlet of the steam-water separator is connected to the shell-side inlet of the condenser. The tube side of the condenser circulates low-temperature seawater through the circulating water pump, the outlet of the shell side of the condenser is connected to the condensate pump, the outlet of the condensate pump is connected to the discharge pipeline, and the discharge pipeline is respectively connected to the fresh water tank and the bypass pipeline. The utility model not only has compact structure, simple control, and small installation and maintenance space, but also improves energy utilization rate, water recovery rate, reduces equipment investment, reduces energy consumption, and greatly improves the reliability and economy of the device.

Description

Miniaturized Positive Pressure Distillation Seawater Desalination System

technical field

The utility model relates to a seawater treatment device, specifically a seawater desalination device.

Background technique

The ship power plant consumes a large amount of fresh water, which is mainly used as cooling water for diesel engines, boiler feed water, and domestic water for crew members. Seawater desalination is an effective way to ensure the continuous and stable supply and replenishment of fresh water required by ships.

The industrialization of marine seawater desalination technology began in the 1950s. Up to now, the international seawater desalination technology has been very mature. Multi-stage flash (MSF), multi-effect distillation (MED) and reverse osmosis (RO) are commonly used. Three mainstream technologies. Multi-stage flash evaporation improves the economy of the seawater desalination plant due to the recycling of heat; because there is no boiling on the heating surface, it avoids scaling and corrosion on the heating surface and improves the feasibility and safety of the device. It is the most widely used and large-scale The largest and most mature seawater desalination technology.

Chinese patents (CN101139119A, CN1724394A and CN101973596A) all introduce a regenerative multi-stage flash seawater desalination device or compressed air flash seawater desalination device and method. These devices make full use of circulating heat to improve thermal efficiency and economy, but their component forms are relatively complicated and their structures are relatively cumbersome. The heat transfer process of low-temperature multi-effect distillation is boiling and condensation heat exchange, with high heat transfer coefficient, low power consumption, simple device and compact structure. Chinese patent (CN202284171U) introduces a low-temperature multi-effect evaporation seawater desalination device with reasonable flow arrangement. The device adopts a new process arrangement of "segmented parallel-downstream feeding", does not set up a separate flash tank, and can use the low-grade waste heat of the power plant to greatly reduce the cost of water production and effectively reduce scaling and corrosion happened. But in the example of this patent, no definite experimental data has been given yet. The modular design of reverse osmosis seawater desalination reduces maintenance requirements, improves reliability, and because of its stable all-electric operation performance, and small size does not require the use of anti-fouling chemicals, it is also used in ships. Chinese patent (CN1583605A) introduces a seawater desalination treatment method and equipment using reverse osmosis and nanofiltration, which can effectively improve the water recovery rate of seawater desalination, simplify investment equipment, and save energy consumption. However, the price of reverse osmosis membrane is relatively high, it is not easy to maintain, and it decays quickly. In general, the quality of reverse osmosis produced water is lower than that of distillation method.

Due to limited space on board and unstable operating environment, marine desalination devices have stricter requirements on volume, reliability, anti-interference ability and product water quality in addition to economical considerations.

Contents of the invention

The purpose of the utility model is to provide a miniaturized positive pressure distillation seawater desalination system that solves the problems of high energy consumption, complex devices, large space occupation, poor fresh water quality and poor anti-interference ability in the prior art.

The purpose of this utility model is achieved in that:

The utility model miniaturized positive pressure distillation seawater desalination system is characterized in that it includes a feedwater preheater, a feedwater pump, an evaporator, a steam-water separator, a condenser, and a condensate pump, and the drain pipe of the evaporator is connected to the feedwater preheater. The heat exchange tube, the water outlet of the feed water preheater is connected to the heat exchange component in the evaporator through the feed water pump, the inlet of the steam-water separator is installed at the steam outlet of the evaporator, and the outlet of the steam-water separator is connected to the shell-side inlet of the condenser. The tube side of the condenser circulates low-temperature seawater through the circulating water pump, the outlet of the shell side of the condenser is connected to the condensate pump, the outlet of the condensate pump is connected to the discharge pipeline, and the discharge pipeline is respectively connected to the fresh water tank and the bypass pipeline.

The utility model can also include:

1. The heat exchange component is a herringbone corrugated plate, the material of which is titanium, and the heat exchange medium is the gas produced or exhausted by the power plant.

2. A water level controller is installed in the evaporator, and an evaporator drain pipe is installed under the evaporator. The drain pipe of the evaporator leads to a sewage pipe and a return pipe. An electric valve is installed on the sewage pipe, and the return pipe is connected to the feedwater preheater and the feedwater pump. Pipeline, the pipeline at the outlet of the feedwater pump is provided with a check valve, the pipeline behind the check valve leads to a side pipeline, and the side pipeline is connected to the pipeline at the water inlet of the feedwater preheater.

3. A salinity sensor is installed on the discharge pipeline, a solenoid valve is installed between the discharge pipeline and the fresh water tank, the solenoid valve and the salinity sensor are connected to a conductivity meter, a valve is installed in the bypass pipeline, and a pressure sensor is installed in front of the valve.

4. The filtered and desalted seawater flows into the feed water preheater, and is preheated by the water discharged from the evaporator;

The preheated seawater is pressurized by the feed pump and sent to the heat exchange component of the evaporator, where it exchanges heat with the primary heating steam and evaporates to generate secondary steam;

The secondary steam carries the salty water droplets through the steam separator to remove the salty water droplets;

The steam that removes the salt water droplets flows into the condenser, and the condenser condenses the secondary steam into fresh water;

Fresh water enters the discharge pipeline and is detected by the salinity sensor. Qualified fresh water is sent to the fresh water tank. For unqualified water, the conductivity meter sends a signal to control the solenoid valve to close. The pressure sensor detects that the pressure of the bypass pipe has risen and exceeded the set value. When the value is reached, the control valve opens to discharge unqualified water.

The utility model has the advantages that: the utility model not only has compact structure, simple control, and small installation and maintenance space, but also improves energy utilization rate, recovery rate of produced water, reduces equipment investment, reduces energy consumption, and greatly improves device performance. reliability and economy.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is a structural schematic diagram of the herringbone corrugated plate heat exchange assembly of the present invention;

Fig. 3 is a cascade control diagram of condensate, heating steam and feed water of the utility model.

Detailed ways

The utility model is described in more detail below in conjunction with accompanying drawing example:

In combination with Figures 1-3, the seawater desalination experimental system of the present invention includes a condenser 1, an evaporator 2, a steam-water separator 3, a water level controller 4, a herringbone corrugated plate heat exchange assembly 5, pressure gauges 6, 17, and a thermometer 7. Differential pressure transmitter 8, flow meter 9, electric control valve 10, stop valve 11, check valve 12, feed water pump 13, feed water preheater 14, condensate pump 15, pressure sensor 16, salinity sensor 18, Conductivity meter 19, solenoid valve 20, sampling cock 21.

The method of this experimental system: Under normal working conditions, open the valves of the water supply pipeline, steam pipeline and fresh water delivery pipeline, and ensure that the valves of the fresh water bypass pipeline and the feedwater pump bypass pipeline are closed. The preheater 14 is preheated by the water from the evaporator at 50°C, heated to 35°C and sent to the evaporator 2 through a feed water pump, and the feed water flow rate is 300kg/h; the heating steam used by the evaporator comes from the gas produced by the power plant or Exhaust, working under positive pressure conditions, heating and evaporating seawater; wet steam flows through the steam-water separator 3 in the back cover of the evaporator, and more than 99% of seawater is separated to obtain high-quality steam; steam in the condenser 1 The condensate is condensed by cooling water at 20°C, and flows into the water inlet of the condensate pump 15 through the condensate pipeline; a salinity sensor 18 is installed on the outlet pipeline of the condensate pump to monitor the salt content of the fresh water produced in real time. Delivered to the fresh water tank, when the salt content exceeds the standard, the solenoid valve 20 is closed, the solenoid valve of the bypass is automatically opened under control, and the unqualified fresh water is discharged overboard.

As shown in Figure 2, the herringbone corrugated plate heat exchange assembly is composed of many pressed titanium metal corrugated plates at certain intervals, and the surrounding areas are sealed by gaskets. Corrosion, easy maintenance, and it is compressed by the frame and clamping bolts. The four corner holes of the plate form the distribution pipe and the collection pipe of the fluid, and the heating steam and the feed water alternately flow between the plates for heat exchange.

As shown in Figure 3, the seawater desalination system uses cascaded control of flow between condensate, heating steam and feed water to realize the fresh water output of the system and the automatic control of the system. When the flow meter of the condensate pipeline detects that the condensate flow is higher (or lower) than the set water production target, the control system sends a signal to control the opening of the electric valve of the steam pipeline to become smaller (or larger), and the steam flow As it becomes smaller (or larger), the output signal of the steam flow transmitter controls the opening of the electric valve of the water supply pipeline to become smaller (or larger), thereby changing the feedwater flow of the evaporator, thereby controlling the fresh water in the seawater desalination system Yield remains constant.

The liquid level controller of the evaporator monitors the water level of the evaporator. When the water level is too high and reaches the maximum water level set by the evaporator, the controller sends a signal to control the electric valve of the sewage pipeline to realize emergency discharge; when the water level exceeds the normal working water level line , adjust the opening of the electric valve to realize intermittent sewage discharge; if the water level of the evaporator is too low, close the electric valve to maintain the water level of the evaporator.

The above-mentioned technical problems of the utility model are mainly solved by the following technical solutions: the basic principle is, firstly, desalination pretreatment is carried out on the seawater, the suspended solids and bacterial microorganisms are filtered, and the possibility of silting and scaling of equipment such as evaporators is reduced; The treated seawater is pumped into the evaporator, heated and evaporated by the exhaust gas of the power plant to generate secondary steam; the steam passes through the high-efficiency steam-water separator to reduce humidity and improve quality, and then flows into the shell-and-tube condenser, where it is condensed into fresh water by low-temperature seawater.

The utility model provides a treatment method for desalination of seawater. Compared with the desalination of seawater by low-temperature distillation, the evaporator and condenser of the experimental system are in a positive pressure state, the specific volume of water vapor is small, and the specific heat of constant pressure is large. The heat exchange area required for the condensation process and the distillation flow resistance are small, which makes the size of equipment and pipelines smaller and the device more compact. The high-temperature distillation condenser has a large temperature difference, is less affected by seawater temperature changes, has strong environmental adaptability, and the device has strong anti-interference ability. Furthermore, the positive pressure system does not require vacuum pumps and salt discharge pumps for vacuuming and waste water extraction, which not only simplifies the system structure and control process, but also eliminates the possibility of air leakage from the device's loose parts, improving system reliability.

The seawater desalination method is carried out in sequence as follows: the pretreated seawater flows into the feedwater preheater 14, and the water discharged from the evaporator 2 is preheated to 35°C; the preheated seawater is pressurized by the feedwater pump 13 and pumped to the plate evaporator 2. Exchange heat with the heating steam and evaporate to generate new steam; the salty liquid droplets carried by the steam will increase the salt content of the produced fresh water, so a steam-water separator 3 is installed in the steam flow space of the back cover of the evaporator, and the wet steam passes through the steam-water separator More than 99% of the seawater droplets are discharged; the dehumidified steam flows into the shell-and-tube condenser 1 through the secondary steam connection pipe, and the low-temperature seawater is pumped into the heat exchange tube of the condenser through the circulating water pump to condense the secondary steam into fresh water; the fresh water delivery pipeline is installed The on-line monitoring conductivity meter 17 is used to monitor the salt content of the fresh water produced in real time. The qualified fresh water is pumped to the fresh water tank through the condensate water tank. If the salinity of the condensate water is detected to exceed the standard, the solenoid valve 20 is closed and the valve of the bypass pipeline is opened. , Drain unqualified fresh water to the bilge.

The fresh water delivery pipeline is divided into a main pipeline and a bypass pipeline, a solenoid valve is installed on the main pipeline, and a pressure sensor and a solenoid valve are installed on the bypass pipeline. When the device is working normally, the solenoid valve of the main pipeline is open, the solenoid valve of the bypass pipeline is always closed, and the fresh water is transported to the fresh water tank through the main pipeline. The instrument sends a signal to control the solenoid valve to close, cut off the channel between the condensate and the fresh water tank, and avoid the pollution of the produced water in the fresh water tank. At the same time, when the pressure sensor 16 detects that the pressure of the bypass pipeline exceeds the set value, the bypass solenoid valve Open to discharge the fresh water with excessive salinity.

The heat exchange element of the evaporator 2 is a herringbone corrugated plate, and the material selected for the plate is titanium, which has strong stress corrosion resistance to chlorides and other salt-containing compounds in seawater. The design of the herringbone corrugation of the heat exchange plate in the utility model makes the fluid strongly turbulent at a low flow rate to prevent dirt from adhering to the surface of the heat exchange plate, so the heat transfer efficiency of the evaporator is very high. Since the heat exchange plates are easy to disassemble, the best heat transfer efficiency and heat exchange capacity can be obtained by adjusting the number of heat exchange plates. The titanium plate evaporator of the utility model is more compact than the traditional copper tube and shell structure, the maintenance frequency of the shutdown is low, and the device efficiency and economy are improved.

The water level of the evaporator is monitored and controlled in real time by the internal water level controller 4, which is connected to the main control system and controls the water level of the evaporator by adjusting the action of the electric control valve of the bypass pipe.

The feed water preheater 14 is a built-in heat exchanger that improves energy utilization, fully utilizes the waste heat of the equipment, uses the evaporator drain as the heat source, and heats the raw water by flowing through the internal heat exchange tubes of the preheater to increase the feed water inlet of the evaporator. temperature, improving device efficiency and economy.

The outlet of the water tank is connected to the inlet of the preheater, and the outlet pipe of the preheater is connected to the inlet of the feed water pump. The feed water pump pumps the feed water from the outlet pipe to the evaporator. After preheating the seawater, it is discharged overboard. Part of the sewage from the evaporator is connected to the inlet of the feed water pump through the sewage pipe as circulating water supply, and the other part is directly discharged out of the cabin through the bypass pipe. The steam inlet is connected, and the condensate tank outlet of the condenser is connected to the water inlet of the condensate pump, and the condensate pump delivers fresh water to the fresh water tank.

The positive pressure distillation seawater desalination process flow is carried out in the following order:

The filtered and desalted seawater flows into the feed water preheater, and is preheated by the water discharged from the evaporator;

The preheated seawater is pressurized and pumped to the plate evaporator by the feed pump, and is exchanged with the primary heating steam for heat exchange and evaporation to generate secondary steam;

The secondary steam carries water droplets with high salinity and flows through the high-efficiency steam-water separator to remove salty droplets and improve steam quality;

The dehumidified steam flows into the shell-and-tube condenser through the secondary steam connection pipe, and the low-temperature seawater is pumped into the heat exchange tube of the condenser through the circulating pump body to condense the secondary steam into fresh water;

An online conductivity meter is installed in the fresh water pipeline to monitor the salt content of the produced fresh water. The qualified fresh water is pumped to the fresh water tank through the condensate pump; if the fresh water salinity is detected to be too high, the conductivity meter sends a signal to control the solenoid valve to close the fresh water pipeline. When the pressure sensor detects that the pressure of the bypass line rises and exceeds the set value, the bypass solenoid valve is controlled to open to discharge unqualified product water.

The working pressure of the evaporator and condenser is the local atmospheric pressure. Positive pressure or normal pressure evaporation is adopted. The specific volume of water vapor is small, which can reduce the size of the device; at the same time, it is not necessary to establish and maintain a stable vacuum, so that the water generation device and its control system can be obtained. Simplified and improved reliability.

The feed water tank makes full use of the waste heat of the equipment to improve the energy utilization rate, uses the evaporator drain as the heat source, heats the raw water through the feed water preheater, increases the inlet temperature of the evaporator feed water, and improves the economy.

The feedwater preheater is connected with the steam drain pipe and the seawater tank. Driven by the feedwater pump, sea water with low hardness passes through the feedwater preheater to exchange heat with the drain from the evaporator to increase the temperature and then flows into the evaporator. The bypass pipeline joins the inlet pipe of the feed water pump, and the other part is directly discharged outboard through the sewage pipe. The steam-water separator is connected with the evaporator by a closed flange and a sealing plate to separate the salty liquid droplets carried by the new steam. The condenser is connected to the evaporator by a secondary steam pipe, the outlet of the condensate tank of the condenser is connected to the water inlet of the condensate pump, and the condensate pump delivers the fresh water to the fresh water tank.

The top of the condenser shell is provided with a safety valve and a vent cock.

The heat exchange element of the evaporator is titanium herringbone corrugated plate, and the plate is fixed by a pressing plate, a pressing screw and a guide rod.

Electric control valves, flowmeters and differential pressure transmitters are installed on the steam inlet pipeline and feedwater pipeline of the evaporator to monitor and control parameters such as steam entering the evaporator, feedwater flow and pressure.

The water level in the evaporator is monitored by the water level controller, and the sewage discharge of the evaporator is controlled by controlling the action of the electric valve of the sewage pipeline.

On-line monitoring conductivity meters and solenoid valves are installed on the condensate pipeline, and pressure sensors and solenoid valves are installed on the bypass pipeline to realize emergency discharge of water with excessive salinity and ensure the stability of freshwater quality in the desalination system.

Claims (9)

1. positive pressure distillation seawater desalination system is minimized, it is characterized in that：Including feed water preheater, feed pump, evaporator, carbonated drink point From device, condenser, condensate pump, the drain pipe of evaporator connects the heat exchanger tube in feed water preheater, the water outlet of feed water preheater Heat-exchanging component in evaporator is connected by feed pump, the import of steam-water separator is mounted on the steam outlet of evaporator, vapour The shell side import of the outlet condenser of separator, the tube side of condenser cycle low temperature seawater, condensation by water circulating pump The shell-side outlet connection condensate pump of device, the outlet connection discharge pipe of condensate pump, discharge pipe are respectively communicated with fresh-water tank and bypass Pipeline.

2. miniaturization positive pressure distillation seawater desalination system according to claim 1, it is characterized in that：The heat-exchanging component is behaved Font corrugated plating, the material of plate is titanium, and the medium for exchanging heat is power set aerogenesis or exhaust.

3. miniaturization positive pressure distillation seawater desalination system according to claim 1 or 2, it is characterized in that：It is set in evaporator Water level controller, sets evaporator drain pipe below evaporator, and evaporator drain pipe draws blow-off pipe and return duct, on blow-off pipe Motor-driven valve is set, and return duct connects the pipeline between feed water preheater and feed pump, non-return is set on the pipeline for the pump discharge that feeds water Valve, the pipeline at check-valves rear draw lateral line, and lateral line connects the pipeline of feed water preheater water inlet.

4. miniaturization positive pressure distillation seawater desalination system according to claim 1 or 2, it is characterized in that：It is set on discharge pipe Salinity sensor to be put, solenoid valve is installed between discharge pipe and fresh-water tank, solenoid valve and salinity sensor are all connected with conductivity meter, By-pass line installs valve, and pressure sensor is installed before valve.

5. miniaturization positive pressure distillation seawater desalination system according to claim 3, it is characterized in that：Salt is set on discharge pipe Sensor is spent, solenoid valve is installed between discharge pipe and fresh-water tank, solenoid valve and salinity sensor are all connected with conductivity meter, bypass Pipe installing valve installs pressure sensor before valve.

6. miniaturization positive pressure distillation seawater desalination system according to claim 1 or 2, it is characterized in that：

Seawater by filtering, desalination pretreatment flows into feed water preheater, the hydrophobic preheating discharged by evaporator；

The seawater of preheating is sent through feed pump supercharging to the heat-exchanging component of evaporator, and heat exchange evaporation is carried out with once heating steam Generate indirect steam；

The water droplet that indirect steam carries saliferous flows through steam-water separator removing saliferous water droplet；

The steam for removing saliferous water droplet flows into condenser, and indirect steam is condensed into fresh water by condenser；

Fresh water enters discharge pipe, is detected through salinity sensor, and the fresh water of quality qualification is sent to fresh-water tank, underproof water, electricity Electrical conductivity instrument send signal control solenoid valve close, pressure sensor monitoring to by-pass line pressure rise and be more than setting value time control Valve opening processed discharges unqualified water.

7. miniaturization positive pressure distillation seawater desalination system according to claim 3, it is characterized in that：

Seawater by filtering, desalination pretreatment flows into feed water preheater, the hydrophobic preheating discharged by evaporator；

The seawater of preheating is sent through feed pump supercharging to the heat-exchanging component of evaporator, and heat exchange evaporation is carried out with once heating steam Generate indirect steam；

The water droplet that indirect steam carries saliferous flows through steam-water separator removing saliferous water droplet；

The steam for removing saliferous water droplet flows into condenser, and indirect steam is condensed into fresh water by condenser；

Fresh water enters discharge pipe, is detected through salinity sensor, and the fresh water of quality qualification is sent to fresh-water tank, underproof water, electricity Electrical conductivity instrument send signal control solenoid valve close, pressure sensor monitoring to by-pass line pressure rise and be more than setting value time control Valve opening processed discharges unqualified water.

8. miniaturization positive pressure distillation seawater desalination system according to claim 4, it is characterized in that：

Seawater by filtering, desalination pretreatment flows into feed water preheater, the hydrophobic preheating discharged by evaporator；

The seawater of preheating is sent through feed pump supercharging to the heat-exchanging component of evaporator, and heat exchange evaporation is carried out with once heating steam Generate indirect steam；

The water droplet that indirect steam carries saliferous flows through steam-water separator removing saliferous water droplet；

The steam for removing saliferous water droplet flows into condenser, and indirect steam is condensed into fresh water by condenser；

Fresh water enters discharge pipe, is detected through salinity sensor, and the fresh water of quality qualification is sent to fresh-water tank, underproof water, electricity Electrical conductivity instrument send signal control solenoid valve close, pressure sensor monitoring to by-pass line pressure rise and be more than setting value time control Valve opening processed discharges unqualified water.

9. miniaturization positive pressure distillation seawater desalination system according to claim 5, it is characterized in that：

Seawater by filtering, desalination pretreatment flows into feed water preheater, the hydrophobic preheating discharged by evaporator；

The seawater of preheating is sent through feed pump supercharging to the heat-exchanging component of evaporator, and heat exchange evaporation is carried out with once heating steam Generate indirect steam；

The water droplet that indirect steam carries saliferous flows through steam-water separator removing saliferous water droplet；

The steam for removing saliferous water droplet flows into condenser, and indirect steam is condensed into fresh water by condenser；

Fresh water enters discharge pipe, is detected through salinity sensor, and the fresh water of quality qualification is sent to fresh-water tank, underproof water, electricity Electrical conductivity instrument send signal control solenoid valve close, pressure sensor monitoring to by-pass line pressure rise and be more than setting value time control Valve opening processed discharges unqualified water.