JPS58219986A - Treatment of geothermal hot water - Google Patents

Abstract

PURPOSE:To reduce the precipitation and the adhesion of dissolved silica to machineries, by a method wherein dissolved silica in geothermal hot water containing dissolved silica in an oversaturated state is grown to a particle with a specific particle size which is in turn separated from hot water by an ultrafiltration membrane. CONSTITUTION:In utilizing geothermal hot water, soluble oversaturated silica in hot water is subjected to colloid growth or coagulation to be grown to a particle with a particle size of 5mmu or more which is in turn separated by using an ultrafiltration membrane to reduce the precipitation of dissolved silica in the filtrate to machineries. In this case, a temp. in colloid growth conditions is pref. about 40-100 deg.C and, in forming and growing a secondary coagulation particle by adding a coagulant, as the coagulant, an Al type, an Fe type, a Ca type or an org. amines are effective.

Description

Detailed Description of the Invention: Geothermal energy is utilized by ejecting high-temperature hot water from underground together with steam, separating the steam and hot water, using the steam for power generation, and flashing the hot water as needed. It is well known that after generating LD secondary steam and lowering the pressure, the heat is used for heating etc., and furthermore, it is used as a hot spring or returned to the ground, and it is actually practiced in 6 places.・In this geothermal utilization, the erupting hot water dissolves the silica in the rock depending on the temperature underground, and coexists with more than several hundred ppm of soluble silica. As the temperature decreases, it becomes supersaturated and deposits in equipment such as water pipes, heat exchangers, and even reinjection wells. This precipitated scale leads to serious troubles such as a decline in the performance of each device and even the inability to use it, and the economic loss is immeasurable. This trouble L occurs based on regional differences (related to changes in other dissolved components).

Many studies have been conducted in the past to solve this problem, but no satisfactory solution has been found. To provide a means of removal.

In the past, research to solve scale problems was carried out in the magazine "Se5dtx J No. 51! No. 2] 810
03[~104N[)rGeothermal power generation and hot water utilization], Magazine “Takashi Hyoron Vol. 28 No. 2 Reprint ax O7Jl[~12
oJ [(@1 Report J, fiiQmlzx Buy ~ 1.2 Buy 1 2nd Report Reaisha Nihon Kagaku Miscellaneous - 1 [R91 Volume #! 1
x! )@s Pages 9-4 Reported in sX Misaki. C
These reports revealed that there is a mutual relationship between the colloidalization process of supersaturated silica in hot water and the adhesion of silica, and it was found that under conditions where the insect removal rate of silica colloid is high, silica does not adhere to the pipe wall. They say that the adhesion is quite noticeable. It has been made clear that lowering the temperature to 50 tons, stirring, a-filtration, and filtration after mixing with river water all have the effect of suppressing colloid formation.

Furthermore, the size of the 9 silica colloid particles was measured using a light scattering method to be approximately 0.03 μm, and it is stated that under conditions that are effective in suppressing colloids, there is little adhesion.

However, although there is an effect of suppressing the adhesion of dirt as mentioned above, it has been reduced and the problem of adhesion of dirt has not been solved (although it still remains a major problem).

The present invention alleviates the problem of silica adhesion and, if necessary, also takes into account the recovery of silica from hot water after particle growth of dissolved silica.

The idea is to separate silica from hot water using an ultramembrane.

Soluble supersaturated silica in hot water forms colloids or aggregates to grow particles to a size of 5 mμ or more. Next, particles that have grown to a size of 5 mμ or more are separated through an ultramembrane. The silica content on the F liquid side depends on the silica particle size and the pH of the liquid.
+Value depending on temperature? The amount of silica scale precipitated changes depending on the properties and amount of silica on the F liquid side.

The solution in which silica particles are grown using simulated hot water is obtained by immersing an iron piece in the filtrate obtained through an ultramembrane to remove the precipitation of silica scale. It was found that the amount of pessilica scale precipitated in the p-liquid that passed through the ultramembrane was small. The measurement conditions for scale precipitation were 40° C. for one week. The following procedure can be used to grow colloids of IJ force from geothermal hot water containing dissolved silica, or to cause particles to grow to a size of 5 mμ or more by coagulation.

By mixing and contacting the already generated silica colloid core with geothermal hot water containing dissolved silica, dissolved silica 1 can be precipitated around the core and grown as a colloid.

Precursor hot water that has essentially already undergone colloidal growth can be used as a nucleus for colloidal growth. The desirable conditions for colloid growth are temperatures between 40°C and 100°C; the higher the temperature, the larger the particle size of the colloid becomes.In addition, the material that should form the nucleus is not only silica, but also precipitates around the nucleus. Any substance that does this can be used. To collect pure silica, it is preferable to use silica colloid cores in hot water as a precursor.

Moreover, even if a coagulant is added, silica forms secondary agglomerated particles and grows. Effective flocculants for silica include A) type, Fe type, Ca type, and organic sludge. By adding a flocculant, f1'f of soluble silica can be reduced. When the concentration of silica is as low as several hundred ppm, even if it is called agglomeration, it does not grow to a size large enough to settle, and it is difficult to separate it using a normal p filter.

It is large enough to be separated by an ultramembrane.

The particle size referred to here is that the secondary particle size is measured by the colloid measurement method, and the aggregate particle size is actually measured by the light scattering method. After the particle size is set to 5 mμ or more, the particles are grown in an ultramembrane and then the silica colloid is separated, and the ultramembrane is shaped like a glue roll.

There are fibrous and plate shapes, but any membrane type can be used. Although there is also a difference in the molecular weight cutoff, as far as practical use is concerned, there is no significant difference in the degree of silica 'a' leaking to the F liquid side.

There is some soluble silica on the F liquid side, but the adhesion of soluble silica to the iron piece varies greatly depending on the temperature, but at 40℃
The results showed that the number of particles that grew and passed through the ultrafilter was smaller.

Examples and comparative examples will be shown below to clarify the effects of the present invention.

Preparation method for hot water simulator: Dissolve 425yvt sodium silicate with a 24% silica concentration in 100kg of pure water and add 11.1wt4 silica! I
100.4 kg of diluted sodium silicate of If was made.

1 diameter row filled with pre-regenerated cation exchange resin <8-IB). Sv in a column of length 200t1n
Pass the lysate through at a speed of 5.

100 ml of silicic acid liquid of 0.1 pt was prepared.

This 0.10 pt silicic acid solution has a concentration of 99.8 and potassium chloride asP of 99.5.
Sodium chloride 244p95.0 Calcium chloride 2.3F99J'l Sodium sulfate 14.8F99.5 Boric acid
10.0 was added to prepare a simulated solution @:.

Hereinafter, it will be referred to as liquid A.

Example 1 99.5% potassium chloride 1.14jl+, 99.5% sodium chloride 7.335F, 95.0% calcium chloride 0.07jl+, 99.5% potassium chloride 0.07jl+ Iy sodium sulfate 0.441!
Weigh out 2.73 liters of 99.5% boric acid, 0.30F of 98% sodium hydroxide, weigh them in advance into container B, and then add these to 2.9% of pure water. The mixture was stirred for 1 hour. This solution contains silica with a particle size of 11.0 mμ and a concentration of 30
Add 10.0 jl of colloidal silica having a high purity, and add pure water while stirring to bring the total volume to 3.0 jl.

Thereafter, the mixture was thoroughly mixed for 10 minutes. This solution is used as a seed solution. Add 3 parts of this seed solution to a refluxing vessel,
04 Pour into a reaction container and heat until it reaches 80℃.

After reaching 80°C, hold for 30 minutes. Thereafter, 40 g of human fluid was added to the seed liquid at a rate of 333.3 ml/i. After adding 407ml of liquid A, 48Jl of this solution was poured into a 150ml reaction vessel equipped with 2 refluxers and a stirrer, and the remaining 60ml of liquid A was added to 333.3m/m.
was added at an addition rate of . After adding the entire amount of solution A, separate the filtrate 102 from the colloid-generated solution 103 using an ultramembrane. After collecting a certain amount of this tear fluid, dip an iron piece into it and measure it using a silica scale.
(Example 2 The temperature of the seed solution and the temperature at the time of adding liquid A were 50°C, and everything was the same as in Example 1 except for the following (Silica scale ILt
- Measured.

Example 3 The amount of silica scale was measured in the same manner as in Example 1 except that the rate of addition of liquid A was tl-666,6rrtl/m. Example 4 f) 9.59g potassium chloride 1.14g, 99.5% Calcium Chloride) lJr'7mu 7.13p, 95.0% Calcium Chloride 0.075! , 99.5% sodium sulfate, 0.449°99, 51 hours! 0.30j
E, 54.2 'i6 5 nium chloride o, zori, 9
Weighed 8 tons of sodium hydroxide and 2.83 liters of sodium hydroxide, and added these to 2.9 tons of pure water that had been weighed in advance in a 5-liter container.
Stirring was performed for hours. Particle size 11.0 mμ in the solution of keratin
, colloidal silica with a silica concentration of 30% 10.
Opt was added, and while stirring, pure water was added so that the total amount was 3.0N. Then mix thoroughly for 10 minutes. This solution is used as a seed solution. Three volumes of this seed solution were poured into a 50 volume reaction vessel equipped with a refluxer and a stirrer, and heated to 80°C.

After reaching 80°C, the temperature was maintained for 30 minutes. Thereafter, after adding 40 nof of human liquid: 333.3 m#/-, 43 no of solution C was poured into a 150 no reaction vessel equipped with a refluxer and a stirrer, and the remaining 60 nof of solution A was added. t-333
Added at an addition rate of 1 penalty/lII#I. After the entire amount of AM had been added, 103 pieces of this colloid product liquid were separated into 102 pieces of filtrate using an ultramembrane. After collecting a certain amount of this filtrate, a piece of iron was immersed in it to measure the silica scale.Comparative Example: In the same manner as in Example 1, 100 parts of liquid A were separated from 99 parts of liquid F using an ultramembrane. k・After taking a certain amount of this F solution, an iron piece was immersed to measure the amount of silica scale □ Comparative Example 2 In the same manner as in Example 1, 100 pieces of A solution were heated to 80°C, and then the temperature was increased to 2 A circle that keeps time. Then p
Separate liquid 991 and form a circle. After collecting a certain amount of this R liquid, the iron piece was immersed and the amount of silica scale was measured.
The amount of silica scale in each P solution was determined.

The results are shown in the following table along with the processing conditions.

(The following is a blank space.) The silica concentration of the p liquid separated from the J-loid production liquid was determined by the following method.

Silica deposition method (according to industrial water test method JI8KO101) A sample is taken in advance in a platinum colander so that the amount of S is approximately o, o sp. This sample is carbonated)
17um 5Pt--Asahi is placed in a boiling water bath and heated to evaporate to shrink to about 40 MItKm.

After cooling, dilute to 50 ml with distilled water and adjust to p) 11.0 with ZN-He. Transfer to a 250-volume flask and dilute to approximately 230 auK. Furthermore, 101 ILl of ammonium molybdate solution (10φ) is added and the mixture is made up to 250 ILl with distilled water and mixed. 420 after leaving for 20 minutes
Measure the absorbance at a wavelength of mμ.

The amount of silica was determined using a calibration curve prepared in advance from the absorbance of the sample.

Moreover, the amount of silica in the silica scale was determined by the following method. An iron piece with 18 cd was immersed in the P solution and left at 40°C for 7 days, after which the iron piece 11 was taken out and thoroughly washed with distilled water.The iron piece was placed in a platinum colander and distilled water was added to about 15 oz.
After adding J, the same procedure as for the silicazene formation of solution F was carried out for 1 degree.

Patent applicant Catalysts Chemical Industry Co., Ltd.

Claims (1)

[Claims] 1. Geothermal hot water containing supersaturated dissolved silica is colloidally grown or coagulated to grow the particle size to 5 m# or more, and then separated using an ultraviolet membrane, and the dissolved silica in the F solution is deposited on the equipment. Geothermal hot water treatment method that reduces