JP2001213620A - Process of producing salt and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process and an apparatus of producing salt capable of obtaining table salt having mellow taste through efficient and through removal of gypsum component not suitable for food in the salt production utilizing sea water. SOLUTION: This process of producing salt comprises the steps of concentrating sea water in a concentration kettle 2 until the salt concentration in sea water becomes around 12 to 15% (the volume of sea water becomes around 22% of original volume), sending the concentrated sear water to a sediment tank 4 for storage, gypsum component being deposited during storage standing still for 2 to 4 hours, discharging the deposited gypsum component from a drain pipe 4a provided at the bottom of the sediment tank 4, sending the concentrated sea water (supernatant) to an evaporating kettle 5 for crystallization and evaporating residual water by heating the evaporating kettle 5 to obtain crystallized salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing natural salt from seawater, and more particularly to a method and an apparatus for removing unedible components (especially gypsum) contained in natural salt. is there.

[0002]

2. Description of the Related Art It is well known that sodium chloride is produced by precipitating sodium chloride out of seawater components. However, in recent years, natural salt (including not only sodium chloride but also seawater) Salts containing mineral components such as calcium and magnesium) have been reviewed and their demand has been increasing.

[0003] The procedure for producing salt in the Irihama-type salt basin and the flowing-down salt basin known as a natural salt production technique since ancient times is generally as follows. In the case of the Iruma-style salt field: (1) Spray seawater on the sand spread over the salt field. (2) After the water of the seawater evaporates due to the sun, the sand to which the salt adheres is collected. (3) The collected sand is put in a marsh (so-called “snow saw”), and seawater is applied to the well to wash out salt attached to the surface of the sand to form a strong salt water. (4) The concentrated salt water thus obtained is boiled down in a kettle to obtain a crystallized salt. In the case of a falling salt field: (1) Flow seawater to a falling plate (inclined plate). (2) The salt water that has evaporated and concentrated while flowing down the falling plate is collected. (3) The salt water that is collected is pumped up onto a branch frame (a stand in which bamboo branches are assembled in several stages), and is gradually dropped to make a stronger salt water. (4) The concentrated salt water thus obtained is boiled down in a kettle to obtain a crystallized salt. As described above, in the inland-type salt field and the down-flow type salt field, salt is produced by removing only the water content of seawater, so that salt containing a large amount of minerals such as calcium and magnesium can be obtained. Similarly, as a method for producing salt using seawater, for example, JP-A-10-1677
No. 23, a salt production method has been proposed.

[0004]

However, seawater contains gypsum (CaSO ₄ ), which is a non-water-soluble component which is not edible, in addition to the above-mentioned minerals which are effective for the human body. However, if a large amount of this gypsum is contained in the manufactured salt, there is a problem that the taste of the salt becomes strongly irritating. Therefore, conventionally, in a concentration process of boiling down seawater, gypsum components floating and precipitated were manually scooped and removed, and it was difficult to say that only gypsum components could be sufficiently removed. The present invention has been made in view of the above-described problems, and when salt is produced using seawater, it is possible to sufficiently and efficiently remove gypsum that is not edible, and to obtain a salt having a mellow flavor. It is an object of the present invention to provide a salt producing method and a device therefor.

[0005]

For this reason, according to the salt production method of the present invention, seawater is boiled down, concentrated until the salt concentration becomes 12% to 15%, and the concentrated seawater is calmed to form gypsum (Ca).
The first feature is that the SO ₄ ) component is precipitated and removed.

[0006] Further, the salt production apparatus of the present invention comprises a concentrating pot for boiling and condensing seawater, a concentration rate judging means for judging a salt concentration of the concentrated seawater, and a gypsum (CaSO ₄ ) component from the seawater concentrated in the concentrating pot. Is characterized by comprising a settling tank for precipitating the gypsum and removing the gypsum, and an evaporating crystal pot for heating and evaporating the concentrated seawater after the removal of the gypsum again to crystallize and precipitate the salt.

First, as a result of intensive experiments, the present inventors, as shown in the graph of FIG. 3, when seawater was boiled down, when the salt concentration of seawater became 12%, gypsum (CaS
Precipitation of O ₄ ) content reaches a peak, after which it is another trace mineral component. MgSO ₄ , MgCl ₂ , KCL
It was found that the precipitation amount of salt (NaCl) became the maximum when the precipitation amount gradually increased and the salt concentration became 25% or more. In other words, when the salt concentration of seawater becomes 12%, only the gypsum is precipitated, so if the concentrated seawater is calmed at that point, most of the gypsum in the seawater will precipitate, The inventors of the present invention have thought that a salt having a mild flavor can be obtained by making a salt only from the supernatant from which the salt has been removed.

[0008] The concentrating pot of the apparatus of the present invention is provided with a storage water tank for storing seawater and a heating means for heating the stored seawater with the steam delivered from the boiler in the storage water tank, and one end of a pipe serving as a steam passage. Concatenate. The other end of this pipe is connected to an evaporation crystal pot described later. Further, the evaporators is connected to one end of a pipe made of the path of the concentrated seawater, and the other end of this pipe is connected to the evaporator crystallizer kettle, in its middle, gypsum (CaSO ₄₎ minutes from the concentrated seawater A settling tank for removal is provided.

[0009] A float type measuring device for measuring the level of the stored seawater and measuring the amount of water stored therein is provided inside the concentrating pot (water storage tank), so that the salt concentration is concentrated to a predetermined ratio. Can be determined. That is, the salt concentration of the concentrated seawater can be determined by measuring the amount of water reduced by evaporation from the seawater due to boiling. Specifically, the salt concentration of concentrated seawater is 12%
At the time of な っ 15%, the concentration is stopped (heating is stopped) and the mixture is sent to the precipitation removing tank.

In the apparatus of the present invention, first, seawater is charged and stored in a concentration tank, and the seawater is heated by the heat of steam generated by a boiler. In this case, steam is sent into the concentrating pot by a heat pipe. Then, the seawater is boiled down and concentrated. Since the concentrated seawater was charged with transported with a pump sedimentation removal tank via a pipe, when the sedated for about 2 hours to 4 hours concentrated seawater sedimentation removal tank gypsum (CaSO ₄₎ fraction is precipitated The precipitated gypsum (CaSO ₄ ) is discharged from a drain pipe provided at the lower end of the settling tank. Then, gypsum (CaSO ₄ )
The concentrated seawater from which the fraction has been removed is transported by a pump to an evaporating crystal pot via a pipe, and reheated in the evaporating crystal pot to crystallize and evaporate the remaining water to obtain a salt.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is an overall system diagram showing a salt producing apparatus according to the present invention, FIG. 2 is a process diagram showing a flow of the salt producing apparatus, and FIG. 3 is a graph showing changes in the amounts of various water-insoluble components deposited due to changes in the salt concentration of seawater. It is.

[0012]

1 is an overall view showing a salt producing apparatus according to the present invention, in which 1 is a boiler apparatus (heating apparatus) for generating steam for heating, 2 is a concentrating pot for boiling down seawater and condensing it,
Reference numeral 3 denotes a float mechanism which is a measuring means for measuring the amount of water reduction from the seawater concentrated in the concentration tank 2 to determine the salt concentration of the concentrated seawater, and 4 denotes a gypsum (Ca) from the seawater concentrated in the concentration tank 2
SO ₄ ) a sedimentation removal tank for precipitating the components and removing the gypsum component;
Reference numeral 5 is an evaporating and crystallizing kettle for heating and evaporating the concentrated seawater again after removing the gypsum to crystallize and precipitate the salt.

The concentrating tank 2 is a water tank for storing pumped seawater, and includes a pipe 1a for introducing steam for heating for introducing steam generated in the boiler device 1 and a pipe 1b for discharging steam for heating introduced. At the same time, a pipe 2a for flowing seawater into the concentration vessel 2 and a concentrated seawater discharge pipe 2b for discharging the concentrated seawater heated and concentrated in the concentration vessel 2 are provided respectively. An opening 2c is provided in the ceiling of the concentrating kettle 1 so that steam generated by heating can be released. A heating heat pipe 6 communicated with the pipe 1a is provided in the concentration tank 2 so that the stored seawater can be concentrated by boiling down.

A float mechanism 3 provided in the concentration tank 2
Is a concentration rate determining means for determining the salt concentration (concentration rate) of the concentrated seawater by measuring the amount of decrease in water content from the concentrated seawater. In the present invention, the normal seawater salt concentration (5% to 6% )
However, the amount of water reduction to 12% to 15% is measured in advance, and when the volume reaches the volume, concentration is stopped (heating is stopped) and sent to the precipitation removing tank 4. In this embodiment, 2000 liters of seawater is concentrated to 436 liters (volume is about 22%). In the present embodiment, steam is used for heating the concentrating vessel 2, but the heating means is not limited to this, and it goes without saying that a heating device using gas or fossil fuel may be used. Also,
The determination of the concentration rate may be simple with a float mechanism, but is not limited to this, and a sensor or the like for chemically determining the salt concentration may be provided.

Further, a pipe 1b for discharging the heated steam is further extended and communicated with the evaporation crystal pot 5, and the boiler 1
The steam generated after heating the concentrating vessel 2 can also be used as a heat source for the evaporating crystal vessel 5.

The sediment removal tank 4 is provided with a pipe 2b through which the seawater concentrated in the concentration tank 2 flows in through a pump 7, and a supernatant after the gypsum (CaSO ₄ ) component is precipitated and removed.
A pipe 4b to be sent out by a pump 8 is attached to the evaporation crystal pot 5, and a drain pipe 4a for discharging settled gypsum is provided at the lower end of the settling tank 4. Then, the concentrated seawater is supplied to the sediment removal tank 4 for 2 hours or more.
If you calm down for about 4 hours, gypsum will precipitate,
The precipitated gypsum is discharged from a drain pipe 4a provided at the lower end of the settling tank. Next, the concentrated seawater (supernatant) from which the gypsum component was removed was sent out to the evaporating crystal pot 5 via the pipe 4b by the pump 8, and was heated again in the evaporating crystal pot 5 to evaporate the remaining water and crystallized. Get the salt. In the figure, 5a is a drain pipe (steam trap) for draining water from a steam pipe.

The operation of this embodiment will be described with reference to the process charts shown in FIGS. First, the seawater pumped from the sea is put into the water tank through the pipes 2a of the two concentration tanks 2.
Next, the steam for heating generated in the boiler device 1 is sent out to the heat pipe 6 by opening the valve, and
The inside is heated to 90 ° C. to 100 ° C., and the seawater is boiled for about 3 hours to 4 hours, and the steam generated by the boiling of the seawater is released from the upper opening 2 c of the concentration tank 2.

In the concentration tank 2, the salt concentration of the seawater is 12% to
The concentrated seawater is concentrated to about 15% (until the seawater volume becomes about 22%), and the concentrated seawater is sent to the settling tank 4 by opening the valve and operating the pump 7 to be stored. The concentrated seawater stored in the sedimentation removal tank 4 is removed for 2 hours to 4 hours.
If the gypsum is settled for a period of time, the gypsum is precipitated, and the gypsum is discharged from the drain pipe 4 provided at the lower end of the settling tank. Finally, the concentrated seawater (supernatant) from which the gypsum component has been removed is branched off by a pump 8 to two evaporating crystal kettles 5 via a pipe 4b and sent out. By evaporating the water, a crystallized salt can be obtained.

[0019]

As described above, according to the present invention, when salt is produced using seawater, only the gypsum component in the seawater can be efficiently removed, and a salt having a mellow flavor can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing a salt producing apparatus according to the present invention.

FIG. 2 is a process chart showing a flow of a salt manufacturing method using a salt manufacturing apparatus.

FIG. 3 is a graph showing a change in the amount of various water-insoluble components deposited due to a change in salt concentration of seawater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler (heating apparatus) 2 Concentration pot 3 Float mechanism (concentration rate judging means) 4 Precipitation removal tank 4a Drain pipe (for discharging gypsum) 5 Evaporation crystal pot 5a Steam trap (for draining) 6 Heat pipe 7 Pump 8 Pump

Claims (2)

[Claims] (1) boil down seawater to obtain a salt concentration of 12% to 15%;
%, And the concentrated seawater is sedated to remove gypsum (CaSO ₄ ) by precipitation. 2. A concentrating pot for boiling and condensing seawater, a concentration rate judging means for judging a salt concentration of the seawater concentrated in the concentrating pot, and gypsum (CaSO ₄ ) from the seawater concentrated in the concentrating pot.
A sedimentation removal tank for precipitating the gypsum component to remove the gypsum component, and an evaporating crystal tank for reheating and evaporating the concentrated seawater after removing the gypsum component to crystallize and precipitate the salt. apparatus.