JPS62106889A - Double-layered bed type dealkalization softening tower - Google Patents

Abstract

PURPOSE:To remove an alkalinity component and to reduce installation cost, by passing raw water through a dealkalization softening tower, in which a double-layered bed consisting of a weak acidic cation exchange resin and a weak acidic cation exchange resin is formed to treat the same. CONSTITUTION:A raw water inflow pipe 5 is communicated with the upper part of an ion exchange tower 1 through a distributor 4 and one end of a treated water outflow pipe 6 is communicated with the lower part of the ion exchange tower 1. An acid regenerating solution inflow pipe 8 is communicated with the upper part of an H-type weak acidic cation exchange resin bed 2 through a regenerating solution distributor 7 and a collector 9 is provided to the intermediate part of both ion exchange resin beds 2, 3 and a waste regenerating solution outflow pipe 10 is communicated with the collector 9. Then, raw water flows in the tower 1 from the raw water inflow pipe 5 to be consistently passed through both ion exchange resin beds while treated water flows out from the treated water outflow pipe 6 and is subsequently treated by a decarbonator 15.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a dealkalization softening tower in which a weakly acidic cation exchange resin and a strongly acidic cation exchange resin are formed in a multilayer bed.

<Prior art> In order to prevent the formation of scale and caustic embrittlement of metals in boiler feed water, etc., dehydration is used to remove hardness components such as calcium ions and magnesium ions and alkalinity components such as hydrogen carbonate ions in raw water. An alkali softener is used.

Conventional dealkalization softening equipment is a combination of an H tower filled with an H-swelling acidic cation exchange resin, an Na tower filled with an Na form-forming acidic cation exchange resin, and a decarboxylation tower.
A typical flow is shown in FIG.

That is, a portion of the raw water is passed through an H tower (b) filled with an H-swelled acidic cation exchange resin (a), and all cations in the raw water are replaced with hydrogen ions by the following reaction.

R-(SO3H) z+ca (HCOz) z-R
(-So 3) zca+2cOz+2HzO"-(1
)R-(S(hll) z0Mg(HCOs) t→R
(-SO3) zMg+ZcO□+2HzO...(2
)R-(SOJ) z+cac It z=R(-3O
s) zca+2Hc l -(3)R-(SOJ)
z+Mgc l t-R(-So:l) Jg+28C
l...(4) R-SO3H+NaHCO3→R-5O
Ja+COz+HzO-(5)R-So, lI+Na
Cl-hR-5OJa+HCI! =-(6) On the other hand, the other part of the raw water is passed through the Na tower (d) filled with Na form-forming acidic cation exchange resin c), and the C in the raw water is removed by the following reaction.
a. Replace Mg ions with Na ions.

R-(SOJa) z+Ca (HCOa) z=
R(-5Ot) zca+2NaHcO:+ ++ (
7) R-(SOJa) z+Mg (I(co:l)
z →R(-3Ot) Jg+2NaHCOz -(8
)R-(SOzNa)z+cac Rz-=R(-3
Os) gca+2Na(: l-(9)R-(SOJ
a) z+Mgc l z-R(-3Oz) zMg+
2NaCl ・= (10) Next, the treated water of the H tower (b) and the treated water of the Na tower (d) are mixed, and the reaction formula (3) is expressed.
, (4) and (6), the hydrogen carbonate ions contained in the treated water of the Na tower (d) are neutralized by the following reaction with the mineral acid contained in the H tower treated water.

NaHCOi+HC1-NaCj! +COz+HzO
・” (11) Next, the mixed water is treated in a decarbonation tower (e) to remove carbon dioxide gas from the mixed water and used as treated water.

Note that the mixed water also contains carbon dioxide gas resulting from reaction formulas (1), (2), and (5).

<Problems to be Solved by the Invention> The conventional dealkalization softening apparatus has the following problems.

In other words, H tower (b) and Na tower (
In addition to requiring two units (d), when mixing the treated water of the H tower (b) and the treated water of the Na tower (d), the H tower (b)
If the treated water in (2) is in excess, the pH of the dealkalized softened water becomes mineral acidic, and conversely, if the treated water in the Na tower (d) is in excess, the amount of bicarbonate ions in the dealkalized water increases, causing the dealkalized softened water to become acidic. cannot achieve its purpose. Therefore, conventional dealkalization softening equipment includes an H tower (b) and an Na tower (
d) A flow rate proportional control mechanism for controlling the flow rate ratio, and measuring the pH of the mixed water to either the H tower (b) or the Na tower (d)? This requires an instrumental control device such as a pH control mechanism to control the Affi, increasing the installation cost of the device.

Furthermore, when regenerating the H tower (b), an acid such as hydrochloric acid is used as a regenerating agent, but strongly acidic cation exchange resins have poor regeneration efficiency and inevitably require more than a chemical equivalent of acid during regeneration, resulting in running costs. It also has disadvantages, such as the fact that it requires an extra alkali to neutralize the acid in the recycled waste liquid.

An object of the present invention is to provide a dealkalization softening device that can solve the above-mentioned drawbacks of conventional dealkalization softening devices and reduce the installation cost and running cost of the device.

<Means for solving the problems> The present invention uses an H-type weakly acidic cation exchange resin as an upper layer, and a Na
A multilayer bed filled with strongly acidic cation exchange resin in the lower layer is formed in the ion exchange tower, and a raw water inflow pipe is connected to the upper part of the ion exchange tower, and a treated water outflow pipe is connected to the lower part of the ion exchange tower. The present invention relates to a multi-layer bed type dealkalization softening tower, characterized in that raw water flows in from the raw water inflow pipe and is passed through the multi-layer bed consistently, thereby obtaining treated water from the treated water outflow pipe. be.

The present invention will be explained in detail below.

Weakly acidic cation exchange resins in the H form are neutral salts in the raw water, namely CaC1, M g S O4, NaCl2, Na1
It does not have the ability to decompose s04, etc., and it does not have the ability to decompose alkaline salts such as Ca (HC03)2, Mg (HCO3
) Z, N a HCO:I, etc. only. In addition, weakly acidic cation exchange resins and strongly acidic cation exchange resins have different sedimentation rates, so they can be easily separated by backwashing. In addition, the weakly acidic cation exchange resin has good regeneration efficiency and can be regenerated with a chemical equivalent of the regenerant, and the throughflow capacity of the weakly acidic cation exchange resin in the H form for the decomposition of alkaline salts is The smaller the Na form is, the larger it is; in other words, it is larger when decomposing Ca salt or Mg salt than Na salt.

The present invention skillfully utilizes the properties of weakly acidic cation exchange resins as described below. Raw water is first passed through an H-type weakly acidic cation exchange resin to remove Ca(HCC)+)z, M in the raw water.
Decompose alkaline salts such as (HC03)z, N a HCO: 1, perform some dealkalization and softening, and then remove neutral salts that could not be decomposed with H-type weakly acidic cation exchange resin. The hardness present in the form i.e. (, aCJ
z, MgS Oa, etc., with a Na-type strongly acidic cation exchange resin, and the above reaction is carried out in a complex of a weakly acidic cation exchange resin and a strongly acidic cation exchange resin formed in a single ion exchange column. This is done on a layered bed.

The present invention will be explained below based on the drawings.

FIG. 1 is an explanatory diagram showing a flow of an example of an embodiment of the present invention, in which an H-type weakly acidic cation exchange resin layer 2 is provided as an upper layer, and a Na-type strongly acidic cation exchange resin layer 3 is provided in an ion exchange column 1. A multilayer bed is formed by filling the lower layer with

A raw water inflow pipe 5 is connected to the upper part of the ion exchange tower 1 via a distributor 4, and one end of a treated water outflow pipe 6 is connected to the lower part of the ion exchange tower. In addition, an acid regenerating liquid inflow pipe 8 is connected to the upper part of the weakly acidic cation exchange resin layer 2 of the form (■) via a regenerating liquid distributor 7, and a collector 9 is connected to the intermediate part of both the ion exchange resin layers 2 and 3. A recycled waste liquid outflow pipe 10 is connected to the collector 9.

Furthermore, a backwash water outflow pipe 11 is communicated with the raw water inflow pipe 5, and a backwash water flow pipe 12, a wash water outflow pipe 13, and a salt regenerating liquid inflow pipe 14 are communicated with the treated water outflow pipe 6, respectively. A known decarboxylation tower 15 is connected to the other end of the treated water outflow pipe 6,
16 to 23 each indicate a valve.

<Function> In the present invention, when raw water is passed through and treated, the valves 16 and 23 are opened, the other valves are closed, and the raw water is allowed to flow in from the raw water inflow pipe 5, and the water is passed through both ion exchange resin layers consistently. death,
The treated water flows out from the treated water outflow pipe 6, and then is treated in the decarbonation tower 15.

Through such treatment, the alkaline salts in the raw water are decomposed by the H-type weakly acidic cation exchange resin layer 2 through the following reaction, dealkalization is achieved, and Ca and Mg, which are the alkaline salts in the raw water, are decomposed by the following reaction. Hardness components such as

R-(COOH) z+Ca ()ICOx) z-
R(-COOH) zca+2cOz+2Hzo-'
(12) R-(COOH) z+Mg (HCO3)
z→R(-COOH) zMg+2cOz+2Hz・
...(13) R-C0011+NaHCO3=R-CO
ONa + COz + HzO- (14) In the H-type weakly acidic cation exchange resin layer 2, Ca and Mg are neutral salts.
Although the hardness components cannot be removed, when they pass through the Na-type strongly acidic cation exchange resin layer 3, they are replaced by Na ions according to the above-mentioned reaction formulas (9) and (10).
The treated water flowing out from the treated water pipe 6 becomes so-called dealkalized softened water. Further, carbon dioxide gas generated according to equations (12) to 14) is removed in a decarboxylation tower 15.

When both ion exchange resins are saturated with each ion by such water flow, the following regeneration is performed.

First, the valve 20 is used to remove suspended matter clogging the ion exchange resin layer by water flow treatment and to loosen the ion exchange resin layer.
and 17 are opened to allow backwash water to flow in from the backwash water flow pipe 12 to expand both ion exchange resin layers, and backwash wastewater containing suspended matter flows out from the backwash water outflow pipe 11.

After performing such backwashing, valves 20 and 17 are closed to settle the ion exchange resin layer. Even if such backwashing is performed, as mentioned above, the strongly acidic cation exchange resin has a faster sedimentation rate, so the upper layer is the weakly acidic cation exchange resin N2.
The multilayer bed with the lower layer of strongly acidic cation exchange resin N3 is maintained.

Next, the valves 18, 19, and 20 are opened to allow an acid regenerating liquid such as hydrochloric acid to flow in from the acid regenerating liquid inflow pipe 8 through the regeneration distributor 7, and at the same time, support water flows in from the backwash water flow pipe 12. The regenerated liquid is brought into contact with the weakly acidic cation exchange resin layer 2 to be regenerated into H-type, and the regenerated waste liquid and support water are discharged from the regenerated waste liquid outflow pipe 10 via the collector 9, and then extruded by a conventional method. conduct.

Next, close the valve 18.20, leave the valve 19 open, and open the valve 16.22 to allow a regenerating liquid such as sodium chloride to flow in from the salt regenerating liquid inflow pipe 14, and at the same time from the raw water inflow pipe 5. Support water flows in, and the regenerated liquid is brought into contact with the strongly acidic cation exchange resin layer 3 to be regenerated into Na form, and the regenerated waste liquid and support water flow out from the regenerated waste liquid outflow pipe 10 via the collector 9, and then The extrusion operation is performed in a conventional manner.

Next, valves 19 and 22 are closed, valve 16 is left open, and valve 21 is opened, raw water as cleaning water flows in from the raw water inflow pipe 5, and cleaning waste water flows out from the cleaning water outflow pipe 13, and both ions are removed. Clean the replacement resin.

After the regeneration operation as described above is completed, the above-mentioned water flow treatment is performed again.

In addition to the above-mentioned method, the regeneration operation was carried out by injecting an acid regenerating solution from above the multilayer bed and passing it consistently through both ion exchange resin layers to regenerate the weakly acidic cation exchange resin into H-form. After that, a salt regenerating solution is introduced in a downward flow from the middle part of both ion exchange resin layers to regenerate the strongly acidic cation exchange resin in the lower layer into Na form, or an acid regenerating solution is introduced from above the multilayer bed. After the weakly acidic cation exchange resin was regenerated into H-form by consistently passing the liquid through both ion exchange resin layers, a salt regenerating solution was similarly flowed from above the multilayer bed to consistently flow through both the ion exchange resin layers. There is a method in which the strongly acidic cation exchange resin in the lower layer is regenerated into the Na form by passing the water through the water, and there is no significant difference in the quality or yield of the treated water with either regeneration method.

In addition, in the regeneration method explained last, the H-type weakly acidic cation exchange resin layer is contacted with a sodium chloride solution as a salt regenerating solution, but the weakly acidic cation exchange resin has almost no ability to decompose neutral salts. Therefore, it will never become Na form.

Next, the filling ratio between the weakly acidic cation exchange resin layer 2 and the strongly acidic cation exchange resin layer 3 will be explained. Specifically, cations such as Ca, Mg, and Na in the form of alkaline salts contained in the raw water are removed by the weakly acidic cation exchange resin layer 2. In addition, the resin amount ratio is such that hard components such as Ca and Mg in the form of neutral salts contained in the raw water can be removed by the strongly acidic cation exchange resin layer 3.

<Effects> As explained above, the present invention decomposes alkaline salts in raw water and removes hardness components in the form of alkaline salts with an H-type weakly acidic cation exchange resin layer in the form of neutral salts. The Na-type strongly acidic cation exchange resin layer from which hardness components should be removed is packed in one ion exchange tower, so there is no need for two towers, an H tower and an Na tower, as in the past. In addition, by mixing the treated water from the H tower and the Na tower as in conventional equipment, the hydrogen carbonate ions in the raw water are removed without neutralizing the hydrogen carbonate ions in the Na tower treated water with the mineral acids in the H tower treated water. The weakly acidic cation exchange resin layer does not decompose neutral salts, so there is no generation of mineral acids. This eliminates the need for additional instrumentation and control equipment, significantly reducing the installation cost of the equipment.

Furthermore, weakly acidic cation exchange resins have good regeneration efficiency, so
When regenerating into H-form using acid regenerating liquid, the amount of regenerating agent used is almost stoichiometric, reducing the running cost of regeneration, and also regenerating so that the regenerated waste liquid does not contain any acid at all. This also makes it possible to completely omit the neutralization treatment of the regenerated waste liquid.

In addition, by first passing the raw water through the H-type weakly acidic cation exchange resin layer, the flow capacity of the weakly acidic cation exchange resin can be increased, and the alkaline salts present in the raw water are Since the hardness component contained in the ion exchange resin can be removed first with the weakly acidic cation exchange resin, the amount of both ion exchange resin used can be reduced.

The present invention will be explained in detail below.

[Example] In an ion exchange column with an inner diameter of 150 tm and a linear length of 2000 mm, 101 pieces of strong acidic cation exchange resin Amberlite (registered trademark, hereinafter the same) IR-12QB were filled, and the weakly acidic cation exchange resin Amberlite was placed above it. IRC-
Filled with 10β of 84, the upper layer is a weakly acidic cation exchange resin,
Forms a multilayer bed with the lower layer made of strongly acidic cation exchange resin,
Raw water was treated under the following conditions.

1. Regenerant usage amount: 35% HC (! 1.6 kg/C (regeneration level 1)
60g/e R) 95% Na C11,Okg/C(
Regeneration level 100g/e R) 2, Water flow condition Water flow LV 28.3m/H (5001/h) Water flow temperature 15℃ 3, Raw water composition Ca"+Mg" 97ppm as CaC0
゜Na” +K“ 43 〃All cations
140 〃 HCO3-63 〃 Mineral acid anion 77 〃 Salt constituent anion 140 1 A 5-cycle water flow test was conducted under the above conditions, and the alkalinity (HCO, ions) was 3 ppm as Ca
co:+, treated water with hardness lppm as CaCO3 or less is 9007! /C was obtained, and the quality and yield of the treated water were the same in each cycle.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the flow of an example of an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the flow of a conventional dealkalization softening apparatus. 1... Ion exchange column 2... Weakly acidic cation exchange resin layer 3... Strongly acidic cation exchange resin layer 4... Distributor 5... Raw water inflow pipe 6... Treated water outflow pipe 7
...Regenerating liquid distributor 8...Acid regenerating liquid inflow pipe 9...Collector 10.
...Recycled waste liquid outflow pipe 11...Backwash water outflow pipe 12.
... Backwash water flow pipe 13 ... Wash water outflow pipe 14.
...Salt regeneration liquid inflow pipe 15...Decarbonation tower 16-23
...Valve (a)...H-swelled acidic cation exchange resin (b)...
H tower (c)... Na form forming acidic cation exchange resin 2)...
・Na tower (e)...Decarboxylation tower layer! Figure 2 Procedural amendment (voluntary) January 1988 73B Commissioner of the Patent Office Black 1) Akira M. 1, Indication of the case 1985 Patent Application No. 246943 2, Name of the invention Multi-layer bed type dealkalization softening Tower 3: Relationship with the case of the person making the amendment Patent applicant address: 5-5-16 Motosa, Bunkyo-ku, Tokyo Name:
(440) Organo Co., Ltd. Representative Nagai
Kunio Ii 4, Agent Address: 113, 812-5151 5. Go to the Detailed Description of the Invention column in the specification subject to amendment) 6. Contents of the amendment Please correct the following matters in the specification. 1. On page 6, lines 3 and 4, the phrase "weakly salty cation exchange resin layer" has been corrected to "weakly acidic cation exchange resin layer." 2. On page 10, line 12, "sodium chloride, etc." is corrected to "sodium chloride liquid, etc." 3. On page 15, line 13, replace r9001/CJ with r.
9000 It/C”. that's all

Claims (1)

[Claims] A multilayer bed filled with an H-type weakly acidic cation exchange resin in the upper layer and a Na-type strongly acidic cation exchange resin in the lower layer is formed in the ion exchange tower, and a raw water inflow pipe is installed in the upper part of the ion exchange tower. A treated water outflow pipe is connected to the lower part of the ion exchange tower, and raw water is flowed in from the raw water inflow pipe and water is consistently passed through the multilayer bed, thereby obtaining treated water from the treated water outflow pipe. A multi-layered dealkalization softening tower.