JPH0985010A - Apparatus for deaeration by heating, method for deaeration by heating, and vacuum distillation apparatus and vacuum distillation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily carry out deaeratian of a solution by providing a deaeration-by- heating mechanism to generate a vapor by heating a solution and deaerates dissolved air, a heat-exchange mechanism to condense the generated vapor by a heat-exchange apparatus, and a discharging mechanism only for the condensed water and evaporated air. SOLUTION: Air in an evaporator 11 is removed by replacing air with a vapor and, after that, the inside of the evaporator 11 is kept in air-free state by being shut from the outside. Then, sea water is led to a pipe 12 in the evaporator 11 to condense the vapor and decrease the pressure of the evaporator 11. The sea water which passes the evaporator 11 is indirectly heated by the vapor, further heated in 11 deaeration tank 13 until the sea water boils, and due to the boiling, dissolved air in the sea water is removed. The sea water from which dissolved air is removed is introduced into a vapor generating chamber 4 of the evaparator 11 through a pipe 15 and, since the inside of the evaporator 11 is at a lowered pressure, evaporation is accelerated. The generated vapor is transported to a cooling and condensing chamber 16 and cooled to become fresh water and separated from concentrated sea water and discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating degassing apparatus and a heating degassing method for a solution, and a vacuum distillation apparatus and a vacuum distillation method for a solution.

[0002]

2. Description of the Related Art As a conventional apparatus and method of this type,
For example, there is one disclosed in JP-A-5-253405. The distillation apparatus disclosed here is a distillation apparatus in which a good condensation environment is created by using steam or mixed solution vapor, and the pressure is reduced by condensation so that distillation can be performed at a temperature lower than the boiling point of atmospheric pressure. Is.

[0003] However, there, only the method of removing the dissolved air of the solution to be introduced into the distiller by boiling under the open air is adopted.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional circumstances, and uses a heating degassing apparatus and method and a depressurizing apparatus that can easily degas a solution. An object of the present invention is to provide a vacuum distillation apparatus and method that can efficiently perform vacuum distillation of a solution without doing so.

[0005]

[Means for Solving the Problems]

(1) The heating degassing apparatus provided by the present invention heats the introduced solution to generate a steam, thereby degassing the dissolved air in the solution, and a heat degassing mechanism for exchanging the generated steam. It is provided with a heat exchange mechanism for condensing in the vessel and an exhaust mechanism for ejecting only the condensed water and the vaporized air.

(2) In the heating degassing method provided by the present invention, most of the gas phase portion in the heating degassing tank is changed to the vapor phase by heating the introduced solution, and most of the dissolved air is discharged. It is characterized in that it is vaporized and only the condensed water and the vaporized air are discharged.

(3) The decompression device provided by the present invention heats the introduced solution to generate steam,
A heating degassing mechanism that degasses the dissolved air in the solution, a heat exchange mechanism that condenses the generated steam in a heat exchanger, and a discharging mechanism that discharges only the condensed water of the steam and the vaporized air. The device, an air discharge mechanism and a steam generation mechanism for replacing the air in the still by discharging it with steam, and the air in the still after replacing the air by steam and discharging it, and then external air enters the still. It is equipped with a shut-off mechanism that shuts off the heat and a heat exchange mechanism for cooling and condensation that cools and condenses the steam to reduce the pressure inside the distiller. And a device for distilling a solution that enables vacuum distillation by itself.

(4) In the vacuum distillation method provided by the present invention, most of the gas phase portion in the degassing heating tank is vaporized by heating the introduced solution, and most of the dissolved air is vaporized. Then, only the vaporized air and the condensed water of the steam are discharged to make a solution with very little dissolved air.To distill this solution, the air in the still is replaced with steam and then discharged. The present invention is characterized in that the solution is distilled by shutting off from the outside to create an air-free environment, cooling and condensing the vapor, and reducing the pressure in the distiller.

A solar water heater can be used to heat the solution in the above inventions (1) to (4).

Here, the principle of the heat degassing and the vacuum distillation in the present invention will be described by taking water as an example based on the principle diagram of the vacuum distillation shown in FIG.

Usually, the amount of air dissolved in water is about 10 to 20 ppm under one atmospheric pressure. Table 1 shows the solubility of air in water quoted from "Chemical Handbook" in water.

[0012]

[Table 1]

The outline of the above principle can be explained by the following flows (1) to (5).

(1) The air in the distiller 11 in the circle is replaced with steam to remove the air, and then the air is shut off from the outside to create an air-free environment.

(2) By passing seawater through the pipe 12 in the distiller 11, steam is condensed and the inside of the distiller is depressurized.

(3) The seawater passing through the distiller 11 is indirectly heated by steam and further heated in the degassing tank 13 until it boils. Dissolved air in seawater is removed by boiling.

(4) Seawater from which dissolved air has been removed is introduced into the steam generation chamber 14 of the distiller 11 by a pipe 15. The introduced seawater evaporates because the inside of the vessel is in a depressurized state. The generated steam moves to the cooling condensing chamber 16 and is cooled into fresh water, which is separated from the seawater concentrated by evaporation and discharged.

(5) A plurality of effect cans 17 are inserted between the steam generating chamber 14 and the cooling condensing chamber 16 in the figure to effectively use the heat quantity and reduce the cooling process.

If there is no air leakage in the distiller 11, the amount of air introduced into the distiller must be the same as the amount of air discharged in the distillate in a stable state. Otherwise, the inside of the distiller will be depressurized or pressurized. Since only air dissolved in the liquid enters and leaves the distiller 11, the dissolved concentration is assumed to be a. Now, assuming that the air pressure equilibrium with a of the steam generation chamber 14 is p ₁ and the air pressure equilibrium with a of the cooling condensation chamber 16 is _pn , the temperature of the cooling condensation chamber 16 is lower than that of the steam generation chamber 14 capacity is large, and p _1> p _n. That is, if p ₁ is a pressure that does not affect heat transfer, then P _n also has no effect. The amount of air dissolved in water at 20 ° C under atmospheric pressure is about 10
It is estimated that the vapor pressure in the vicinity of the gas-liquid contact portion of boiling water is 1 atm and the air pressure _pn is almost 0. a is very small because it is a dissolved concentration that equilibrates with this air pressure. It is 0 in Table 1. If p ₁ is about _pn, it is sufficiently low. If p _n <p ₁ , p ₁ is sufficiently pressurized with respect to a and T ₀ > T ₁ , so that air gradually dissolves in the liquid. It will be p _n > p ₁ . 10-2
Most of the dissolved air of 0 ppm passes through the heat exchanger 19 from the steam discharge pipe 18 and is discharged together with the condensed water. If T ₀ is 100 ° C. or higher and the condensed water is sufficiently discharged by the heat exchanger 19, the deaeration tank 13 is filled with steam and p ₀ becomes almost 0.

Further, changes with time of the thermometer 20 and the pressure gauge 21 in the figure were measured. FIG. 2 shows the measurement results and shows the change with time in pressure at the same temperature. The decompression has become a little stronger over time. This is considered to be because when the air in the distiller was replaced with steam, a small amount of air remained in the vessel, and the air was dissolved and eliminated by the liquid having no dissolved air introduced into the vessel.

Although the result of the experiment for a short time, the fact that the decompression was intensified due to the discharge of a small amount of air remaining in the distiller 11 is proof that this process can be operated for a long time. That is, if a is made sufficiently low, continuous vacuum distillation becomes possible.

In the present invention, the air in the distiller 11 is discharged in advance to block the entry of external air into the distiller 11, and the pressure reduction state is maintained by condensation to enhance the distillation efficiency and to dissolve in the solution. The generated steam from the degassing heating device that removes the generated air is guided to a heat exchanger equipped with a means for discharging condensed water, and the generated steam releases heat and discharges only the condensed condensate, thereby effectively using the generated steam. Be stripped. Further, most of the dissolved air vaporized can be discharged together with the discharge of the condensate. A steam trap is one of the means for discharging condensed water.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of a vacuum distillation apparatus showing an embodiment of the present invention.

In the figure, 1 is a deaeration tank, 2 is a deaeration steam discharge pipe, 3 is a heat exchanger, and 4 is a condensate discharging means (steam trap or the like). The heating and deaerating device has the above-mentioned element
It is composed of ~ 4. The degassing tank 1 is heated, and water is 1
It has a pressure of 760 mmHg above 00 ° C. Heat exchanger 3
The condensate condensed in (1) dissolves vaporized dissolved air and is discharged from the condensate discharging means 4. Since the air introduced into the degassing tank 1 is only the dissolved air of the solution, the air in the vapor phase portion of the degassing tank 1 is the vaporized portion of the dissolved air in the stable state, and the vaporized air is the degassing tank 1 The solution is dissolved in the condensed water of the heat exchanger 3 having a lower temperature than the solution, and is discharged to the outside.

Reference numeral 5 represents a vacuum distiller. This vacuum distiller 5
Is divided into a heating chamber 7 and a cooling chamber 6 by a partition plate 8. The vacuum distiller 5 expels air from the air discharge pipe 14 and the external shutoff valve 15, and the inside of the vacuum distiller 5 is filled with steam and shut off from the outside. The steam that is heated in the heat exchanger 3 and generated is cooled in the heat exchanger 10, and the condensate is discharged from the condensate discharge pipe 13. The concentrated liquid that has generated steam is discharged from the concentrated liquid discharge pipe 12.

The solution introduced into the degassing tank 1 is a liquid introducing pipe 9
And is introduced into the heat exchanger (cooler) 10. Then, it is heated to a temperature above the boiling point of the solution in the degassing tank 1 and degassed, enters the heating chamber 7 through the liquid introducing pipe 11 for distillation, and is heated by the heat exchanger (heater) 3.

The embodiment shown in FIG. 4 is a deaeration tank that ensures deaeration.

There are two degassing tanks 1, and the solution discharged from the first degassing tank 1 is further degassed in the second degassing tank 1. The heat source of the second degassing tank is the degassing steam of the first degassing tank. Other mechanisms are the same as in FIG.

FIG. 5 shows a degassing tank in which degassing is made more reliable as in FIG.

There are two degassing tanks 1, and the solution discharged from the first degassing tank 1 is further degassed in the second degassing tank 1. The heat source of the second degassing tank is the degassing steam of the first degassing tank. The other mechanism is the same as the third mechanism.

FIG. 6 shows an example in which the present invention is applied to a multi-effect can.

The depressurizing device for the multi-effect can is omitted, the degree of depressurization is determined by the temperature of the final cooling condensing chamber, and the temperature of the degassing tank is set to a temperature equal to or higher than the boiling point of the solution. A vacuum glass tube type collector may be used as the degassing tank and heated by solar heat. Each tank of the effect can was equipped with an air outlet and a shutoff valve for shutting off from the outside. The steam for displacing air is used for heating and heat recovery. The effect cans 1 to (n + 1) have the same function as the vacuum still of FIGS. The steam generated in the effect can (n-1) becomes the heat source of the effect can n, and the steam generated in the effect can n becomes the heat source of the effect can (n + 1).

[0034]

As described above, the present invention has the following effects.

(1) The solution can be easily degassed.

(2) Vacuum distillation of the solution can be efficiently performed without using a vacuum device.

[Brief description of drawings]

FIG. 1 is a principle diagram illustrating the principle of the present invention.

FIG. 2 is an experimental result demonstrating that depressurization can be continuously maintained using the technique of the present invention.

FIG. 3 is a configuration diagram of a vacuum distillation apparatus showing an embodiment of the present invention.

FIG. 4 is a configuration diagram of a vacuum distillation apparatus showing an embodiment of the present invention.

FIG. 5 is a configuration diagram of a vacuum distillation apparatus showing an embodiment of the present invention.

FIG. 6 is a configuration diagram of a vacuum distillation apparatus showing an embodiment of the present invention.

[Explanation of symbols]

 1 Deaeration Tank 2 Degassing Steam Discharge Pipe 3 Heat Exchanger 4 Condensate Discharge Means 5 Vacuum Distiller 6 Cooling Chamber 7 Heating Chamber 8 Partition Plate 9, 11 Liquid Inlet Pipe 10 Heat Exchanger 12 Concentrated Liquid Discharge Pipe 13 Condensation Liquid discharge pipe 14 Air discharge pipe 15 External shutoff valve

Claims (4)

[Claims] 1. A heating degassing mechanism for degassing dissolved air in the solution by heating the introduced solution to generate steam, and a heat exchange mechanism for condensing the generated steam in a heat exchanger. A thermal deaerator equipped with a discharge mechanism for discharging only the condensed water and the vaporized air. 2. The introduced solution is heated to make most of the vapor phase portion in the heating degassing tank into a vapor phase, and most of the dissolved air is vaporized, so that only the condensed water and the vaporized air are produced. A method for degassing by heating, which comprises discharging 3. A heating degassing mechanism for degassing the dissolved air in the solution by heating the introduced solution to generate steam, and a heat exchange mechanism for condensing the generated steam in a heat exchanger. A heating deaerator equipped with a discharge mechanism that discharges only condensed water of vapor and vaporized air, an air discharge mechanism and a steam generation mechanism for replacing the air in the distiller with steam, and discharging the distiller. After the air is replaced with steam and discharged, a shut-off mechanism that shuts off the outside air from entering the still and a heat exchange mechanism for cooling and condensation that cools and condenses the steam to reduce the pressure inside the still, Make the inside of the still without air,
A vacuum distillation apparatus consisting of a distillation apparatus for a solution that enables vacuum distillation only with a temperature difference without using a vacuum apparatus. 4. The solution introduced is heated to turn most of the gas phase in the degassing heating tank into a vapor phase, and most of the dissolved air is vaporized, so that only vaporized air and condensed water of vapor are condensed. Is discharged to form a solution with a very small amount of dissolved air, and in order to distill this solution, the air in the still is replaced with steam and discharged, and then the inside of the still is shut off from the outside to create an air-free environment,
A vacuum distillation method, characterized in that the solution is distilled by cooling and condensing the vapor and reducing the pressure in the still.