JPH0631519B2 - Dual-purpose treatment method for geothermal water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is applied to the inside of a geothermal water piping system and the inner wall of a reduction well when the geothermal water after the energy is effectively used is returned to the underground. The present invention relates to a treatment method for preventing scale adherence and a treatment method for heating river water and the like by geothermal water energy and using it for commercial purposes such as hot water supply and heating.

(Prior art) Since geothermal water generally contains silica, which is a scale component, when these low-temperature hot water is returned to the reduction well, these scale components precipitate on the wall of the reduction well. It becomes a resistance of the flow path, reduces the processing capacity of the reduction well, and finally causes a serious problem of blockage.

For this reason, a measure to prevent scale from adhering to the reduction well can be considered, and prior arts thereof include JP-A-57-51393 and JP-B-59-49077.

According to Japanese Patent Laid-Open No. 57-51393, while maintaining a state in which geothermal water is sealed from the atmosphere, an acid is added thereto to adjust the pH to 4 to 6 under a temperature condition in which colloidal silica is not formed, and a reduction well is provided. A method has been proposed to prevent clogging due to scale adhesion in the reduction well by reducing the amount of water to the water.
In the 9077 publication, a cooling pipe is provided internally, and a heat exchange part in which a fluidized bed is arranged outside the cooling pipe, and a cooling part and a cooling part following the cooling part are circulated to the reduction well through the cooling pipe, The waste heat water that has been cooled in the fluidized bed to remove scale components by precipitation is heated again in the cooling pipe to be reduced to a reducing well, and a method for preventing scale adhesion in the reducing well is proposed. ing.

On the other hand, geothermal water is used for industrial purposes such as power generation, crop drying,
It can be used directly for consumer use in a wide variety of areas such as food processing, hot water pool, hotbed, facility horticulture, district heating, and snow melting, but if this is directly introduced to the indirect heat exchanger to use geothermal water, There is a big problem that a situation such as scale adhesion to the wall surface of the heat transfer tube occurs, the heat exchange capacity of the indirect heat exchanger is significantly lowered, and the passage thereof is blocked.

As a prior art for reducing this adverse effect, Japanese Patent Publication No. 57-4
No. 7827 discloses that silica content in geothermal hot water is added with a Ca 2 ⁺ -based substance at the heat exchanger inlet side to form a calcium salt, which is separated and removed at the heat exchanger outlet side. A geothermal water utilization system has been proposed in which heat is exchanged with geothermal water in a heat exchanger and used as high-temperature hot water for consumer use.

(Problems to be Solved by the Invention) In the method of the above-mentioned JP-A-57-51393, which is a prior art for preventing scale adhesion in a reduction well, only the sedimentation of silica is delayed, and Silica that has been cooled and saturated with water remains as it is, and there is a problem in that it is not possible to completely prevent clogging of the silica in the reduction well, and in the method of Japanese Patent Publication No. 59-49077. , The scale such as silica adheres to the surface of the cooling pipe inside the fluidized bed due to the decrease in solubility accompanying the cooling of geothermal water, but it is decided to scrape it off with particles such as sand. It was not easy to remove the silica scale by sand and there was a problem that the outer surface of the cooling pipe was damaged by sand.

Further, in the method of Japanese Patent Publication No. Sho 57-47827, which is a prior art for preventing scale adhesion in an indirect heat exchanger, the silica content becomes calcium salt, which is sent to the removal device at a low temperature in the heat exchanger and is separated after calcium salt separation. The hot water heat exchanger inlet temperature of
Cold water is added to control the temperature set by the temperature control valve, but cold water has to be introduced from the outside and it is not economical because it is used only for temperature control. There was such a problem.

On the other hand, these prior arts each have a separate processing method and must be individually installed as equipment, and thus there is a problem in terms of profitability.

The present invention is directed to overcoming the aforementioned problems in the prior art.

(Means for Solving the Problem) Therefore, according to the present invention, a considerable amount of scale components contained in geothermal water are removed and discharged to the outside of the system, and the return to the reduction well is performed without any hindrance. The dual purpose of raising the cold water such as river water and lake water as a heat exchanger refrigerant that has effectively acted on the precipitation and separation of the contained scale components to the desired use temperature and using the hot water for consumer use Compact 1
It is a treatment method that can be carried out by two systems, high temperature geothermal water is flowed in series to a plurality of indirect contact heat exchangers to be cooled, and after removing the scale components precipitated by this cooling,
It is used as a refrigerant for geothermal water by guiding it to a part of the heat exchanger, and the refrigerant heated by heat exchange is sent out to return to the reduction well, and cold water such as river water is sent to the remaining heat exchanger. Introduced as a refrigerant of geothermal water, characterized in that the cold water heated to a desired temperature by heat exchange is taken out as hot water.
The purpose is to provide a dual-purpose treatment method for geothermal water.

(Operation and effect) In the present invention, the scale component such as silica contained in the geothermal water is cooled by flowing through a plurality of heat exchangers, the solubility is lowered and supersaturated to precipitate a solid. For example, the geothermal water that has undergone sedimentation and separation of scale components is used as a part of the refrigerant in the heat exchangers provided in series as described above, and becomes high temperature due to heat exchange to increase the solubility of scale components and reduce the saturation to below Since the content is discharged to the outside of the system and returned to the reduction well, it is possible to prevent precipitation on the wall of the reduction well even if the temperature is low.

On the other hand, by sending river water or the like to a part of the refrigerant in a series heat exchanger to cool it and making it a desired temperature by heat exchange, it is used for consumer use such as agriculture, heating, and bathing. With a single compact device, it can be used comprehensively for industrial and consumer use, and dual purpose processing can be achieved.

The heat exchanger used here may be a multi-tube type, or a plate type heat exchanger having a small capacity and high heat exchange performance can be used.

Thus, according to the present invention, it is considered separately in the past,
In addition, as for the equipment, there is an effect that the two treatment methods, which are individually installed, can be effectively treated by one system.

Needless to say, when geothermal water containing a large amount of silica is cooled, silica scale is generated on the cooling surface, which not only deteriorates the heat exchange performance, but also eventually causes blockage, which makes operation impossible. . Here, the heat transfer surface is rubbed with solid particles such as sand particles and the heat transfer performance is improved due to turbulence. However, another method for delaying the deposition of silica scale is pH adjustment, which may be used.

(Example) In FIG. 1, a multi-tube type high temperature side heat exchanger 1 and a low temperature side heat exchanger 2 are provided, a trunk side 3 is connected by a pipe 4, and a pipe 5 is connected to a settling tank 6. I am in touch. The pipe side 7 of the high temperature side heat exchanger 1 communicates with the settling tank 6 via a pump 80, and the pipe side 8 of the low temperature side heat exchanger 2 is introduced with river water by a pipe 9.

In the above device, geothermal water of about 95 ° C was introduced from the pipe 10, the pH was lowered by the acid injection device 16 ', and then the high temperature side heat exchanger 1 reached about 70 ° C, and the low temperature side heat exchanger 2 About 30
After reaching the temperature of .degree. C., it enters the settling tank 6 through the pipe 5, and the scale component precipitated due to the decreased solubility is settled and separated in the settling tank 6 and taken out of the pipe 12 through the pump 11. The supernatant liquid of the settling tank 6 is taken out from the overflow pipe 13, and pump 80, pipe 14
After passing through the pipe side 7 of the high temperature side heat exchanger 1 and exchanging heat with the geothermal water and being heated to about 55 ° C., it is sent out of the system through the pipe 15 and returned to the reduction well.

On the other hand, the river water is introduced from the pipe 9, passes through the pipe side 8 of the low temperature side heat exchanger 2, is heated to about 60 ° C., and is then taken out from the pipe 16 to be used for civilian use. It is used for both industrial and consumer purposes in a compact way.

Figure 2 is a flow sheet of equipment for obtaining hot water of higher temperature for civilian use. The body side 20 of the three heat exchangers 17,18,19 are connected in series and the river water is piped. 21 to low temperature heat exchanger 19
The hot water having a desired temperature of about 70 ° C. is obtained from the pipe 25 by passing through the pipe side 22, the pipe 23 and the pipe side 24 of the high temperature heat exchanger 17.

On the other hand, when returning to the reduction well, the pH of the geothermal water of about 95 ° C introduced from the pipe 26 was lowered by the acid injection device 26 ', and then the three heat exchanger shell sides 20 were flowed in series to cool. , Settling tank via pipe 27
After the scale component is settled and separated by 28, the overflowed supernatant passes through the pump 29 and the tube 30 to exchange heat with the tube side 31 of the medium temperature heat exchanger 18 to heat to about 55 ° C., and then is reduced by the tube 32. Return to the well.

In this way, the temperature of hot water used for consumer use can be adjusted to a desired temperature by increasing or decreasing the number of heat exchangers or changing the heat transfer area, and the dual purpose for industrial consumer use can be achieved.

FIG. 3 and FIG. 4 show another embodiment in which a plate heat exchanger is adopted as the heat exchanger and solid particles are used for scale prevention, as in the case of FIG. 1 and FIG. A plate heat exchanger with different temperatures and a settling tank are provided, and in FIG. 3, the geothermal water inlet header section 33 and the outlet header section are provided.
A plurality of plates A having holes 34 and a plurality of plates B having holes for cooling water inlet 35 and outlet header 36 are stacked to form a high temperature side heat exchanger 37 and a low temperature side heat exchanger 38. Geothermal water is introduced from the pipe 39 into the plate space a of the high temperature side heat exchanger 37, and solid particles such as sand grains existing in the plate space a are maintained at a speed equal to or higher than the terminal velocity thereof to maintain the plate space a. After passing through it, it is cooled, flows out of the pipe 40 and enters the low temperature heat exchanger 38, and again passes through the plate interval a and is cooled, and then enters the solid particle separator 42 through the pipe 41.
The geothermal water, in which the sand particles are separated and cooled, enters the settling tank 44 through the pipe 43, the scale component precipitated by cooling is settled and separated, and the supernatant liquid overflows the overflow pipe 45 and passes through the pump 46. , About 30 ° C, high temperature heat exchanger via pipe 47
The plate interval b of 37 is lowered and the plate is separated by an interval a.
It exchanges heat with the geothermal water of, heats up to about 55 ° C, and returns from the pipe 48 to the reduction well. In the plate space b of the low temperature heat exchanger 38, the river water of about 10 ° C introduced from the pipe 49 flows and exchanges heat,
The temperature itself rises to about 60 ° C and is taken out of the pipe 50 and used for commercial purposes.

The sand particles separated by the solid particle separator 42 are pump 51 and pipe 52.
After passing through the pipe, it is mixed with the geothermal water introduced from the pipe 39, and the sand grains prevent the scale from depositing on the plate surface by rubbing it, and reduce the film on the plate surface, which is effective for heat transfer.

Fig. 4 is a flow sheet of equipment for further increasing the temperature of hot water used for consumer use.
Three sets of low-temperature heat exchangers 53, 54, 55 are provided, the plate intervals a provided for each heat exchanger are connected in series in the order of the heat exchangers, and hot water at a desired temperature is River water pipe 56
From the low-temperature heat exchanger 55 to the plate interval b, and through the pipe 57 to the high-temperature heat exchanger 53 to the plate interval b.
Take hot water of about 70 ℃ from.

On the other hand, when returning to the reduction well, the sand grains from the pipe 60 were mixed with the geothermal water of about 95 ° C introduced from the pipe 59, and then three sets of heat exchangers were used.
53, 54, 55 are placed in parallel plate intervals a to cool and pipe
Take out from 61 through solid particle separator 62, and settling tank from pipe 63
The scale component that has been introduced into 64 and is precipitated by cooling is settled and separated, and the supernatant liquid overflows the overflow pipe 65 and the pump 66
Then, the temperature becomes about 30 ° C. and the plate interval b of the medium temperature heat exchanger 54 is lowered through the pipe 67 to exchange heat with the geothermal water to raise the temperature to about 55 ° C. and return from the pipe 68 to the reduction well. The operation of the solid particles is the same as in the case of FIG.

As is clear from each of the above embodiments, the present invention heats the cooled geothermal water after the scale component separation with a single device and sends it out of the system, and returns it to the reduction well to prevent scale precipitation. Can achieve the dual purpose of obtaining hot water of desired temperature,
The effect is great.

[Brief description of drawings]

1 to 4 are flow sheets of different embodiments of the present invention. 1 ... High temperature side heat exchanger, 2 ... Low temperature side heat exchanger, 3 ... Body side, 6 ... Sedimentation tank, 7 ... Pipe side, 13 ... Overflow pipe, 16 '... Acid injection device, 17 …… High temperature heat exchanger, 18 …… Medium temperature heat exchanger, 19 …… Low temperature heat exchanger, 20 …… Cylinder side, 22 …… Tube side, 24 …… Tube side, 26 ′ …… Acid injection device, 28 ... Settling tank, 31 ... Pipe side, 33 ... Geothermal water inlet header section, 34 ... Outlet header section, 35 ... Cooling water inlet header, 36 ... Outlet header, 37 ... High temperature side heat exchange Vessel, 38 …… low temperature side heat exchanger, 42 …… solid particle separator, 44 …… sedimentation tank, 45 …… overflow tube, 53 …… high temperature heat exchanger, 54 …… medium temperature heat exchanger, 55 …… Low temperature heat exchanger, 62 ... Solid particle separator, 64 ... Sedimentation tank, 65 ... Overflow pipe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-51393 (JP, A) JP-B 57-42827 (JP, B2) JP-B 59-49077 (JP, B2)

Claims (4)

[Claims] 1. High-temperature geothermal water is passed through a plurality of indirect contact heat exchangers in series for cooling, the scale components precipitated by this cooling are removed, and then the heat is introduced to a part of the heat exchanger to conduct geothermal heat. It is used as a refrigerant for water, and the refrigerant heated by heat exchange is sent out to return to the reduction well, and cold water such as river water is introduced to the remaining heat exchanger as a refrigerant for geothermal water, which is used for heat exchange. A dual-purpose treatment method for geothermal water, wherein the cold water heated to a desired temperature is taken out as hot water. 2. The dual-purpose treatment method for geothermal water according to claim 1, wherein the heat exchanger is a multitubular heat exchanger. 3. The dual-purpose treatment method for geothermal water according to claim 1, wherein the heat exchanger is a plate heat exchanger. 4. The dual-purpose treatment method for geothermal water according to claim 3, wherein solid particles are mixed in the geothermal water.