JPS63296801A - Continuous vacuum distillation method using head difference - Google Patents

Abstract

PURPOSE:To enable stable vacuum distillation in a simple manner, at low cost and under feasible control by transporting a system fluid using a head difference and operating a system by control of only a vacuum pump used as a direct power source. CONSTITUTION:A vacuum pump 8 is installed in a fresh water condensation tank 7, and sea water sucked through a suction pipe 1 is heated by a heating coil 16, passing through the tank 7. Then the heated sea water is supplied to an evaporation tank 4 with evaporation shelves 5. The evaporation shelves 5 are provided in the evaporation tank and the supplied water is vaporized there. The vapor is sent to a fresh water condensation tank through an evaporation transport pipe 6 provided at the top to be condensed into fresh water. The concentrated water is stored in a concentrated water storage tank 12. When a vacuum is kept at a constant level in this device, the accumulation of concentrated sea water and condensed fresh water occurs, resulting in the formation of liquid columns reaching the heads according to their respective specific gravities. At that time, opening their respective discharge pipes to an atmosphere permits the liquids to spontaneously flow out of the discharge pipes so that their respective heads may be balanced.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Technical Field The present invention relates to a continuous vacuum distillation method using the difference in water head of the i(Q) form.

B. Prior art The concept of vacuum distillation is well established, and a wide variety of distillation techniques have been put into practical use. However, these processes involve the handling of liquid within the system, the large number of storage tanks, pumps, etc.
And they require instruments etc. to control their operation.
It has a fairly complex configuration. These increase not only the construction cost of the t9 equipment, but also the equipment maintenance cost and operating cost.

C0 Purpose This invention solves the above-mentioned drawbacks of the conventional method, and provides a continuous vacuum distillation method that has a simple structure, is easy to operate, and requires less operating energy.

D. To make the configuration easier to understand, a drawing assuming seawater distillation is attached. The principle will be explained with reference to this.

This process consists of a pipe that sucks up seawater, a tank that evaporates fresh water from seawater and at the same time stores the concentrated seawater, a pipe that sends water vapor, a tank that receives water vapor, condenses it, and stores it, and maintains a vacuum inside the system. It consists of a vacuum pump and a seawater heater as auxiliary equipment. Except for the seawater heater, everything else is the same system.

When the seawater suction pipe under atmospheric pressure is opened and the concentrated water discharge pipe and fresh water discharge pipe are closed, the equipment system is brought to a predetermined vacuum state.The seawater is evacuated to O. through which the water head rises to a balanced height. The water supply pipe leading to the evaporation tank is somewhat lower than this water head, so seawater drips into the evaporation side of the evaporation tank.

Water evaporates in this evaporation tank depending on the degree of vacuum in the system and the temperature of the seawater. Is it possible to accelerate evaporation by preheating the seawater using a heating medium heated by solar heat or by heating the evaporation tank, or is it possible to realize evaporation at a similar degree of vacuum? This will happen.

While water evaporates in the evaporation tank as described above, concentrated seawater that cannot be completely evaporated under this vacuum and temperature accumulates.

The evaporated water vapor is drawn by a vacuum pump and collected in a fresh water condensing tank, where it is cooled by a seawater/fresh water heat exchanger, condensed, and stored in the tank. Once stored, the condensed water comes into direct contact with the heat exchanger, increasing the cooling effect (on the other hand, it helps preheat the seawater to the evaporation tank), and the steam is sucked out into the condensed water, further increasing the condensation. It will help.

If the vacuum is kept constant, the supply of seawater and water evaporation will continue, and concentrated seawater and condensed fresh water will continue to accumulate, creating a liquid column with a height that reaches a water head corresponding to the specific gravity of each and the degree of vacuum. .

At this point, each exhaust pipe is opened to the atmosphere. Here, against the vacuum in the system, the head of seawater that continues to be sucked in, the head of concentrated seawater that has been stored, and the head of fresh water that has been condensed and stored are all balanced.

The main purpose is to pull out the air from the water, but if you continue to operate the vacuum pump and maintain the vacuum, the above evaporation,
Condensation and condensation continue, and the excess amount of concentrated seawater that continues to accumulate and condensed fresh water naturally flows out of the discharge pipe in an attempt to maintain the balance of the water head.

E. Effects As explained above, according to the present invention, the only equipment in the system that requires direct power is the vacuum pump, and process control can be limited to maintaining the degree of vacuum.

Because the structure is extremely simple, construction, operation, and maintenance costs can be kept low, and stable continuous operation can be achieved with easy control.

[Brief explanation of the drawing]

The figure shows an outline of the equipment configuration and process when the present invention is applied to seawater distillation. Below is an explanation of each part in the diagram. 1. Water suction pipe (heats seawater under atmospheric pressure) 2. Seawater fresh water heat exchanger 3. Water supply pipe (sends seawater to the evaporation tank) 4. Evaporation tank 5. Evaporation side 6. Kamata feed pipe 7. Fresh water condensing tank 8, vacuum pump 9, steam/water separator 10, exhaust pipe 11, fresh water discharge pipe 12, a fine ice storage tank 13, a fine ice discharge pipe 14. Heat medium heater 15, heat medium feed pipe 16, heating coil 17, heat medium return pipe 8, m water head B, fresh water head C0 Arrows in the concentrated water head system indicate fluid flows.

Claims (1)

[Claims] When a system in which a constant vacuum (not necessarily a complete vacuum) is kept in contact with a liquid at atmospheric pressure, the liquid is sucked up by the vacuum force within the system, causing a difference in pressure from the atmospheric pressure. The liquid column head is obtained according to the specific gravity of the liquid. If it is connected to an evaporation tank in the same system at a height slightly lower than this water head, this liquid will flow into this tank. When the liquid is heated in this evaporation tank, evaporation progresses depending on the degree of vacuum and temperature within the system. At the same time, liquid that cannot be evaporated at this degree of vacuum and temperature is left behind, but this liquid has a higher specific gravity than the original liquid, and if this is stored and the lower part of the liquid column is released to atmospheric pressure, the original liquid will be restored. It will balance at a lower head than the liquid. On the other hand, the steam is drawn to a tank in the same system that is the source of the vacuum, and is simultaneously cooled and condensed. When this is stored in a tank, a liquid column of condensate is created. This liquid has a lower specific gravity than the original liquid, so when the lower part of the liquid column is opened to atmospheric pressure, it will balance at a higher head than the original liquid. In this way, the combination of maintaining vacuum, supplying the original liquid, heating in the evaporator tank, evaporating, concentrating, storing the concentrate, and cooling the vapor, condensing, and storing the condensate in the condensing tank can be performed continuously in the same system. By doing so, separation of liquids is achieved, and each separated liquid maintains its own liquid column head under a constant vacuum, and if it can be stored at a height above the water head, the balance with atmospheric pressure will be increased by that height. The liquid will collapse and naturally flow out from the bottom of the liquid column. A continuous vacuum distillation method that utilizes a water head difference that includes these continuous processes.