CA1080376A - Process for regeneration of mixed anion and cation exchanged resins - Google Patents
Process for regeneration of mixed anion and cation exchanged resinsInfo
- Publication number
- CA1080376A CA1080376A CA294,172A CA294172A CA1080376A CA 1080376 A CA1080376 A CA 1080376A CA 294172 A CA294172 A CA 294172A CA 1080376 A CA1080376 A CA 1080376A
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- resin
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- separated
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Abstract
ABSTRACT OF THE DISCLOSURE
A regeneration of mixed anion and cation exchange resins is carried out by back-washing the mixed anion and cation exchange resins to separate them as an upper layer, a middle layer and a lower layer, regenerating respectively the upper layer and the lower layer and mixing the separated middle layer of the mixed resins in a step before the back-washing step in the next or following regeneration process.
A regeneration of mixed anion and cation exchange resins is carried out by back-washing the mixed anion and cation exchange resins to separate them as an upper layer, a middle layer and a lower layer, regenerating respectively the upper layer and the lower layer and mixing the separated middle layer of the mixed resins in a step before the back-washing step in the next or following regeneration process.
Description
V~'7~;
The present invention relates to a process for the regeneration of anion and cation exchange resins which are used in a mixed condition, It is known to employ a mixed bed deionizing process using a mixture of an anion exchange resin and a cation exchange resin for producing a deionized water. The mixed bed deionizing process comprises a back-washing separation step for separating the anion exchange resin from the cation exchange resin using a water flow from the bottom of the resin column; a regeneration step for regenerating respectively the separated anion exchange resin and the cation exchange resin with an acid and a base; a washing step for washing out the regenerant with wash water and a mixing step for mixing the ~, regenerated resins.
In the back-washing separation step, the resins are ~ --separated based upon the difference of specific gravities of the resins and the difference of the particle diameters of the resins. However, at the boundary of the separated resins, small amounts of both of the resins are mixed and the complete separation can not be easily attained. The incomplete separ-ation of both of the resins causes a decrease in the regener-ative efficiency of the regenerant in the next regeneration step, a decrease of the exchange capacity of the ion exchange resins and a decrease of the quality of the deionized water after the regeneration. ~ -Recently, the condensed water in a high pressure ' boiler of a fossile fuel power station or an atomic power station has been purified by deionizing with a mixed bed comprising a hydroxyl type (OH type) strong basic anion exchange resin and an ammonium type (NH4 type) strong acidic cation exchange resin. However, in the regenerations of the ion exchange resins, complete separation of the ion exchange .
. . - . .- - ............ - -.. , .. . . - -V3'~6~
resins could not be attained and for example, the ion exchange resins are separated with mixing a small amount of the cation exchange resin in the layer of the anion exchange resin near the lower boundary. When the anion exchange resin containing the small amount of the cation exchange resin is regenerated with sodium hydroxide by the conventional process, a small amount of sodium type cation exchange resin is included in the I OH type anion exchange resin.
In the ammonium type mixed bed process, ammonia is added to adjust the pH of the condensed water which is recycled, whereby sodium ions adsorbed on the contaminated cation ex-change resin are eluted by ammonium ions. For example, when 1% of the sodium type cation exchange resin is incorporated, about several tens ppb (parts per billion) of sodium ions are eluted. The presence of sodium ions in the condensed water causes corrosion of the boiler because of the alkaline corrosion. Accordingly, it is preferable to prevent the ; contamination of sodium ions as far as possible.
The present invention provides a process for a regeneration of mixed anion and cation exchange resins by a simple operation without a decrease of the regenerative efficiency of the regenerant, a decrease of the exchange capacity of the ion exchange resins and a decrease of the ~- quality of the deionized water.
According to the present invention there is provided a process for regenerations of an anion exchange resin and a cation exchange resin used for deionizing water in the form of a mixed resins, the improvement which comprises separating the anion exchange resin and the cation exchange resin as the upper and lower layers by back-washing the mixed resins with water and discharging a middle layer containing non-separated i resins at the boundary between the upper and lower layers, and , ., - ~ ' ' . . ~ .
~080376 charging the discharged middle layer in a step before the back-washing step in a subsequent regeneration process.
Thus in accordance with the present invention regeneration has been effected by back-washing the mixed anion and cation exchange resins to separte them as an upper layer, a middle layer and a lower layer and regenerating respectively the upper layer and the lower layer and mixing the separated middle layer of the mixed resins in a step before the back-washing step in a subsequent regeneration process.
When the mixed anion and cation exchange resins are separated by the back-washing separation, the anion exchange resin and the cation exchange resin are respectively in the pure condition depending upon the distance from the boundary between both of the resins whereby the mixed anion and cation exchange resins are separated into three layers of the pure anion exchange resin layer, the mixed resin layer and the pure cation exchange resin ~ayer. When the three layers are treat~d by the specific process, the deionization and the regeneration can be smoothly attained.
In the present invention, when the anion exchange resin and the cation exchange resin used for the deionization in the form of the mixed resins, are regenerated, the anion and cat~on exchange resins are separated by the back-washing and the middle layer of the mixed resins adjacent the boundary between both of the resins is discharged out of the system, and it is added to a step before the back-wa~hing step in a subsequent regeneration process.
Thus when the mixed anion and cation exchange resins used in the deiDnization are separated by the back-washing separation, the anion exchange resin is separateddas the upper -~
layer and the cation exchange resin is separated as the lower layer and the mixed resins remain as the middle ~ayer. When :, : . .
. ~
~0~3376 the resins are treated by feeding the back-washing water at constant flow velocity, the resin layers are separated in the form of the suspension with stable layers of the resins under back-washing to discharge them with the upward flow.
In the process of the present invention, after the resins are separated under said conditions, the anion exchange resin layer is discharged through an upper layer resin trans-ferring pipe disposed at the upper position in the column with upward flow water or downward flow water after settling the resins. Then, the middle layer of the mixed resins is dis-charged through a mixed resin transferring pipe disposed adjacent the boundary between both of the resin layers with water. The lower layer of the cation exchange resin is regenerated in the column or discharged from the bottom the column to separate the three layers.
The three layers in the condition of the suspension due to ~he back-washin~ sepLaration can be also separated by ~.
sequentially discha~ging the lower layer of the cation exchange resin layer, the middle layer of the mixed resins and the upper layer of the anion exchange resin through a resin transferring pipe disposed at the bottom of the column.
It is also possible to treat them as follows.
The resins separated into three layers by the back-washing are sedimented in three separated condition after finishing the back-washing. The upper layer of the anion exchange resin is `~ discharged together with the downward flow from the upper part of the column, through a resin transferring pipe disposed at suitable position in the upper part of the column. The middle layer of the mixed resin is discharged together with the downward flow fed from the upper part of the column~ through a mixed resin transferring pipe. The lower layer of the cation exchange resin can remain in the column or be discharged :
,.......... I '.'~' ', ~ . ' ' ~ ' ' i3'76 from the bottom thereof, The amount of the middle layer of the mixed resins discharged depends upon the condition of the resin particles and the back-washing method, and it is usually in a range of 3 to 50 wt. % preferably 5 to 20 wt. % to total resins. The middle layer of the mixed resins discharged before the first regeneration is added to the mixed resins before the back-; washing separation in the next or following regeneration process.
The pure anion exchange resin and the pure cation exchange resin which are respectively separated from the middle layer of the mixed resins, are respectively regenerated with a base or an acid, and then, the regenerants (base or -acid) are respectively removed by washing with water and the -resins are mixed and used for the deionization of water. In such a case, the amount of the resins is decreased for the amount of the discharged middle layer of the mixed resins.
: Accordingly, new resins corresponding to the discharged middle layer of the mixed resins are added.
The mixed resins obtained by the deionization are separated by the back-washing separation with water before the second regeneration process. The back-washing separation is carried out after adding the separated middle layer of the mixed resins discharged before the first regeneration process.
As the same manner, in the third or following re-generation processes, the middle layer of the mixed resins separated by the back-washing separation in the previous regeneration process is added in a step before the back-washing separation in the following regeneration process.
The ion exchange resins are slightly broken by repeating the regeneration process whereby the pulverized particles are accumulated in the middle layers. Accordingly, 108~376 the pulverized particles can be removed by a classification of the particles such as a sieving operation for the middle layer of the mixed resins.
In accordance with the process of the present invention~ the anion exchange resin and the cation exchange resin can be regenerated after the complete separation in the back-washing separation after the deionization whereby the regenerants can be effectively used and the ion exchange capacity of the ion exchange resins is not deteriorated and the quality of the deionized water is not deteriorated to obtain the deionized water having high purity. When they are used for the deionization of the condensed water in the high pressure boiler for a power station, the deionized water having high purity can be obtained because of no contamination of the sodium type anion exchange resin. :
, When hydrazine or the other compound is used instead ~. ~
of ammonia for adjusting pH of the condensed water, the -~
desired result as that of the use of ammonia can be attained.
. ~ .
The present invention will be further illustrated ~ 20 by way of the following Examples.
I Example 1 In a column having a diameter of 8 cm and a height of 150 cm, 2 liters of strong acidic cation exchange resin -(supplied under the Trademark Diaion SKlBL by Mitsubishi Chem.
- Industries Ltd.) (hereinafter referred to as SKlBL) and 1 liter of strong basic anion exchange resin (supplied under the Trademark Diaion SA 10 AL by Mitsubishi Chemical Industries Ltd,) (hereinafter referred to as SAlOAL) were charged and thoroughly mixed.
The particle size distributiolls of these resins ~' are shown in Table 1.
~ ..
~ 6 . -- :
- . ~
.- . . .
,' 1 :
10~ 76 Table 1 Particle diameter SKlBL SAlOAL
more than 840,c~ 27. 9 % 4 . 7 %
840 to 590~ 57.1 % 55.4 %
590 to 420,~ ' 14. 8 % 39. 7 %
les s than 42 0~ O . 2 % O . 2 %
: -Three resin transfer pipes having a diameter of 8 mm were disposed at the positions of 48 cm, 53 cm and 58 cm from the bottom of the column.
Deionized water was fed to flow in an upward current at a linear velocity (L~ of 10 m/hr. at 20 + 1C from the bottom of the column for 45 minutes to back-wash the resin.
The resin SA 10 AL separated as the upper layer was discharged through a resin transfer pipe disposed at the position of 58 cm from the bottom during the back-wash. Then, the mixed resin as the middle layer was discharged throush a resin transfer pipe disposed at the position of 4 8 cm from the bottom. The amounts and components in the upper layer, the middle layer and the lower layer of the separated resins in the column were as shown in Table 2.
Table 2 . -.'' ' , .. ' .
_ Volume of Components of resins resin (Volume %) (llter) SK lBL I SA loAL
upper layer O. 88 less than ~ more than 99. 9 ___ .
middle layer O . 31 61. 3 3 8. 7 .... _ , lower layer ~11 ~ 7 .
.
Reference l In accordance with the process of Example l, the mixed resins having the same components were washed by the back-wash and the separated upper layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom of the column as the conventional process. The results are shown in Table 3.
Table 3 . j -Volume of resin Components of resin . (liter) (Volume %) ! SK 1 l~L S~ 1 Ol~L
_ upper layer O . 97 1. 3 98. 7 lower layer 2 . 03 97. 9 1 2.1 . ~-Ex~mple 2 In accordance with the process of Example l using the same resins and the same column, deionized water was fed to flow in an upward current at a linear velocity of 7 m/hr. at 20 + 1C from the bottom of the column for 30 minutes to back-wash the resin. The resin SAlOAL separated as the upper layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom under the back-wash. Then, the back-wash was continued at the linear velocity of 13-m/hr.
for lO minutes and the resin of the middle layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom.
The amounts and components in the upper layer~ the middle layer and the lower layer of the separated resins in the column were as shown in Table 4.
.- 8 -Table4 ._ _ _ .
Volume ofresin Components ofresins (liter) (Volum~ %) _._ __ _ SKlBL SA1OAL
upperlayer ~.89 lessthan morethan . middlelayer 0.24 54.2 45.8 lowerlayer 1.87 1 morethan O 1 ~:
Example 3 -.-- -In an acrylic resin column having a diameter of 8 cm and a length of 150 cm equipped with three resin transfer pipes,
The present invention relates to a process for the regeneration of anion and cation exchange resins which are used in a mixed condition, It is known to employ a mixed bed deionizing process using a mixture of an anion exchange resin and a cation exchange resin for producing a deionized water. The mixed bed deionizing process comprises a back-washing separation step for separating the anion exchange resin from the cation exchange resin using a water flow from the bottom of the resin column; a regeneration step for regenerating respectively the separated anion exchange resin and the cation exchange resin with an acid and a base; a washing step for washing out the regenerant with wash water and a mixing step for mixing the ~, regenerated resins.
In the back-washing separation step, the resins are ~ --separated based upon the difference of specific gravities of the resins and the difference of the particle diameters of the resins. However, at the boundary of the separated resins, small amounts of both of the resins are mixed and the complete separation can not be easily attained. The incomplete separ-ation of both of the resins causes a decrease in the regener-ative efficiency of the regenerant in the next regeneration step, a decrease of the exchange capacity of the ion exchange resins and a decrease of the quality of the deionized water after the regeneration. ~ -Recently, the condensed water in a high pressure ' boiler of a fossile fuel power station or an atomic power station has been purified by deionizing with a mixed bed comprising a hydroxyl type (OH type) strong basic anion exchange resin and an ammonium type (NH4 type) strong acidic cation exchange resin. However, in the regenerations of the ion exchange resins, complete separation of the ion exchange .
. . - . .- - ............ - -.. , .. . . - -V3'~6~
resins could not be attained and for example, the ion exchange resins are separated with mixing a small amount of the cation exchange resin in the layer of the anion exchange resin near the lower boundary. When the anion exchange resin containing the small amount of the cation exchange resin is regenerated with sodium hydroxide by the conventional process, a small amount of sodium type cation exchange resin is included in the I OH type anion exchange resin.
In the ammonium type mixed bed process, ammonia is added to adjust the pH of the condensed water which is recycled, whereby sodium ions adsorbed on the contaminated cation ex-change resin are eluted by ammonium ions. For example, when 1% of the sodium type cation exchange resin is incorporated, about several tens ppb (parts per billion) of sodium ions are eluted. The presence of sodium ions in the condensed water causes corrosion of the boiler because of the alkaline corrosion. Accordingly, it is preferable to prevent the ; contamination of sodium ions as far as possible.
The present invention provides a process for a regeneration of mixed anion and cation exchange resins by a simple operation without a decrease of the regenerative efficiency of the regenerant, a decrease of the exchange capacity of the ion exchange resins and a decrease of the ~- quality of the deionized water.
According to the present invention there is provided a process for regenerations of an anion exchange resin and a cation exchange resin used for deionizing water in the form of a mixed resins, the improvement which comprises separating the anion exchange resin and the cation exchange resin as the upper and lower layers by back-washing the mixed resins with water and discharging a middle layer containing non-separated i resins at the boundary between the upper and lower layers, and , ., - ~ ' ' . . ~ .
~080376 charging the discharged middle layer in a step before the back-washing step in a subsequent regeneration process.
Thus in accordance with the present invention regeneration has been effected by back-washing the mixed anion and cation exchange resins to separte them as an upper layer, a middle layer and a lower layer and regenerating respectively the upper layer and the lower layer and mixing the separated middle layer of the mixed resins in a step before the back-washing step in a subsequent regeneration process.
When the mixed anion and cation exchange resins are separated by the back-washing separation, the anion exchange resin and the cation exchange resin are respectively in the pure condition depending upon the distance from the boundary between both of the resins whereby the mixed anion and cation exchange resins are separated into three layers of the pure anion exchange resin layer, the mixed resin layer and the pure cation exchange resin ~ayer. When the three layers are treat~d by the specific process, the deionization and the regeneration can be smoothly attained.
In the present invention, when the anion exchange resin and the cation exchange resin used for the deionization in the form of the mixed resins, are regenerated, the anion and cat~on exchange resins are separated by the back-washing and the middle layer of the mixed resins adjacent the boundary between both of the resins is discharged out of the system, and it is added to a step before the back-wa~hing step in a subsequent regeneration process.
Thus when the mixed anion and cation exchange resins used in the deiDnization are separated by the back-washing separation, the anion exchange resin is separateddas the upper -~
layer and the cation exchange resin is separated as the lower layer and the mixed resins remain as the middle ~ayer. When :, : . .
. ~
~0~3376 the resins are treated by feeding the back-washing water at constant flow velocity, the resin layers are separated in the form of the suspension with stable layers of the resins under back-washing to discharge them with the upward flow.
In the process of the present invention, after the resins are separated under said conditions, the anion exchange resin layer is discharged through an upper layer resin trans-ferring pipe disposed at the upper position in the column with upward flow water or downward flow water after settling the resins. Then, the middle layer of the mixed resins is dis-charged through a mixed resin transferring pipe disposed adjacent the boundary between both of the resin layers with water. The lower layer of the cation exchange resin is regenerated in the column or discharged from the bottom the column to separate the three layers.
The three layers in the condition of the suspension due to ~he back-washin~ sepLaration can be also separated by ~.
sequentially discha~ging the lower layer of the cation exchange resin layer, the middle layer of the mixed resins and the upper layer of the anion exchange resin through a resin transferring pipe disposed at the bottom of the column.
It is also possible to treat them as follows.
The resins separated into three layers by the back-washing are sedimented in three separated condition after finishing the back-washing. The upper layer of the anion exchange resin is `~ discharged together with the downward flow from the upper part of the column, through a resin transferring pipe disposed at suitable position in the upper part of the column. The middle layer of the mixed resin is discharged together with the downward flow fed from the upper part of the column~ through a mixed resin transferring pipe. The lower layer of the cation exchange resin can remain in the column or be discharged :
,.......... I '.'~' ', ~ . ' ' ~ ' ' i3'76 from the bottom thereof, The amount of the middle layer of the mixed resins discharged depends upon the condition of the resin particles and the back-washing method, and it is usually in a range of 3 to 50 wt. % preferably 5 to 20 wt. % to total resins. The middle layer of the mixed resins discharged before the first regeneration is added to the mixed resins before the back-; washing separation in the next or following regeneration process.
The pure anion exchange resin and the pure cation exchange resin which are respectively separated from the middle layer of the mixed resins, are respectively regenerated with a base or an acid, and then, the regenerants (base or -acid) are respectively removed by washing with water and the -resins are mixed and used for the deionization of water. In such a case, the amount of the resins is decreased for the amount of the discharged middle layer of the mixed resins.
: Accordingly, new resins corresponding to the discharged middle layer of the mixed resins are added.
The mixed resins obtained by the deionization are separated by the back-washing separation with water before the second regeneration process. The back-washing separation is carried out after adding the separated middle layer of the mixed resins discharged before the first regeneration process.
As the same manner, in the third or following re-generation processes, the middle layer of the mixed resins separated by the back-washing separation in the previous regeneration process is added in a step before the back-washing separation in the following regeneration process.
The ion exchange resins are slightly broken by repeating the regeneration process whereby the pulverized particles are accumulated in the middle layers. Accordingly, 108~376 the pulverized particles can be removed by a classification of the particles such as a sieving operation for the middle layer of the mixed resins.
In accordance with the process of the present invention~ the anion exchange resin and the cation exchange resin can be regenerated after the complete separation in the back-washing separation after the deionization whereby the regenerants can be effectively used and the ion exchange capacity of the ion exchange resins is not deteriorated and the quality of the deionized water is not deteriorated to obtain the deionized water having high purity. When they are used for the deionization of the condensed water in the high pressure boiler for a power station, the deionized water having high purity can be obtained because of no contamination of the sodium type anion exchange resin. :
, When hydrazine or the other compound is used instead ~. ~
of ammonia for adjusting pH of the condensed water, the -~
desired result as that of the use of ammonia can be attained.
. ~ .
The present invention will be further illustrated ~ 20 by way of the following Examples.
I Example 1 In a column having a diameter of 8 cm and a height of 150 cm, 2 liters of strong acidic cation exchange resin -(supplied under the Trademark Diaion SKlBL by Mitsubishi Chem.
- Industries Ltd.) (hereinafter referred to as SKlBL) and 1 liter of strong basic anion exchange resin (supplied under the Trademark Diaion SA 10 AL by Mitsubishi Chemical Industries Ltd,) (hereinafter referred to as SAlOAL) were charged and thoroughly mixed.
The particle size distributiolls of these resins ~' are shown in Table 1.
~ ..
~ 6 . -- :
- . ~
.- . . .
,' 1 :
10~ 76 Table 1 Particle diameter SKlBL SAlOAL
more than 840,c~ 27. 9 % 4 . 7 %
840 to 590~ 57.1 % 55.4 %
590 to 420,~ ' 14. 8 % 39. 7 %
les s than 42 0~ O . 2 % O . 2 %
: -Three resin transfer pipes having a diameter of 8 mm were disposed at the positions of 48 cm, 53 cm and 58 cm from the bottom of the column.
Deionized water was fed to flow in an upward current at a linear velocity (L~ of 10 m/hr. at 20 + 1C from the bottom of the column for 45 minutes to back-wash the resin.
The resin SA 10 AL separated as the upper layer was discharged through a resin transfer pipe disposed at the position of 58 cm from the bottom during the back-wash. Then, the mixed resin as the middle layer was discharged throush a resin transfer pipe disposed at the position of 4 8 cm from the bottom. The amounts and components in the upper layer, the middle layer and the lower layer of the separated resins in the column were as shown in Table 2.
Table 2 . -.'' ' , .. ' .
_ Volume of Components of resins resin (Volume %) (llter) SK lBL I SA loAL
upper layer O. 88 less than ~ more than 99. 9 ___ .
middle layer O . 31 61. 3 3 8. 7 .... _ , lower layer ~11 ~ 7 .
.
Reference l In accordance with the process of Example l, the mixed resins having the same components were washed by the back-wash and the separated upper layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom of the column as the conventional process. The results are shown in Table 3.
Table 3 . j -Volume of resin Components of resin . (liter) (Volume %) ! SK 1 l~L S~ 1 Ol~L
_ upper layer O . 97 1. 3 98. 7 lower layer 2 . 03 97. 9 1 2.1 . ~-Ex~mple 2 In accordance with the process of Example l using the same resins and the same column, deionized water was fed to flow in an upward current at a linear velocity of 7 m/hr. at 20 + 1C from the bottom of the column for 30 minutes to back-wash the resin. The resin SAlOAL separated as the upper layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom under the back-wash. Then, the back-wash was continued at the linear velocity of 13-m/hr.
for lO minutes and the resin of the middle layer was discharged through the resin transfer pipe disposed at the position of 53 cm from the bottom.
The amounts and components in the upper layer~ the middle layer and the lower layer of the separated resins in the column were as shown in Table 4.
.- 8 -Table4 ._ _ _ .
Volume ofresin Components ofresins (liter) (Volum~ %) _._ __ _ SKlBL SA1OAL
upperlayer ~.89 lessthan morethan . middlelayer 0.24 54.2 45.8 lowerlayer 1.87 1 morethan O 1 ~:
Example 3 -.-- -In an acrylic resin column having a diameter of 8 cm and a length of 150 cm equipped with three resin transfer pipes,
2.0 liters of strong acidic cation exchange resin (Diaion SKlBL) and 1.0 liter of strong basic anion exchange resin (Diaion SAlOAL~ were charged and mixed and used in the follow-: ing first to seventh steps. ~ -. ~irst step: Deionized water was fed to flow in an -upward current at a linear velocity of 10 m/hr. at 20 - l~C
from the bottom of the column for 20 minutes to back-wash and the separated upper layer of the resin SAlOAL was discharged . 20 through the upper resin transfer pipe at the position of 58 cm from the bottom and transferred to an anion regeneration.column. .
Second step: The mixed resins as the middle layer was discharged through the lower resin transfer pipe at the position of 48 cm from the bottom, Third step: The mixed resins as the middle layer discharged in the second step were sieved in the wet condition with a sieve at 297 ~ (3apanese Industrial Standard).
~ourth step: The resin transferred to the anion regeneration column and the residual resin the column were respectively regenerated with 4 liters of 4% aqueous solution of sodium hydroxide and 8 liters of 4% aqueous solution of sulfuric acid during 1 hour. Then, a deionized water was ~ 9 ,.
.... : . .: . ~ . . . . .......... . . .
108~)376 passed at a rate of 30 liter/hr. and 60 liter/hr, for 1 hour to wash the resins, Fifth step: The resin in the anion regeneration column obtained by regenerating and washing with water was fed into the main column and a compressed air was fed from the bottom of the column for 10 minutes to mix the regenerated anion and cation exchange resins.
Sixthstep: Water was filled to cover the resin and an aqueous solution containing 7.1 ppm of NaCQ (as CaCO3) and 1.52 ppm of ammonia (as CaCO3) at pH of 9.2 was passed at a rate of 300 liters/hr. for 4 hours. -Seventh step: The resins in the middle layer from which fine particles of the resins were removed in the third step were mixed with the resins in the column treated in the -, sixth step.
The first to seventh steps were repeated for five times. The total amount of the resins removed in the third step was 9.7 mQ.
Example 4 The anion and cation exchange resins of Example 3 were , used and water (pH of 9.2) prepared by adding 1.52 ppm (as CaCO3) of ammonia to a deionized water containing 0.02 ppm of sodium ions and an electric conductivity of less than 0.1 ~/cm, was fed at a rate of 300 liters/hr. After 150 hours, the deionized water treated had an electric conductivity of 0.14 ~v/cm and a concentraton of sodium ions of 2.3 ppb.
Reference 2 The first to seventh steps of Example 3 were modified as follows, In accordance with the conventional process, the anion exchange resin as the upper layer was discharged through the resin transfer pipe at the position of 53 cm from the bottom and the anion and cation exchange resins were regenerated -' ' ' : '' ' ~"': ~.. '''"' ' '' . ' '` :
-, ..
10~(~376 and mixed. Then, as the process of Example 3, the water containing ammonia was passed. After 150 hours, the deionized water treated had an electric conductivity of 0.21 ~v/cm and a concentration of sodium ions of 12 ppb.
First step: A deionized water was fed to flow in an upward current at a linear velocity of 10 m/hr. at 20 - 1C
for 20 minutes to back-wash and then, the resin in the upper layer was discharged through the resin transfer pipe at the ~; position of 53 cm from the bottom and transferred to the anion regeneration column.
Second and third steps: None.
Fourth, fifth and sixth steps: The treatments being the same with those of Example 3.
Seventh step: None.
, The deionized water obtained by the process of Example 4 had an electric conductivity of 0.14 ~/cm and a concentration of sodium ions of 2.3 ppb whereas in Reference 2 as the . conventional process, a deionized water had an electric conductivity of 0.21 ~/cm and a concentration of sodium ions of 12 ppb. In accordance with the present invention, the deionized water having a content of sodium ions 1/5,2 to that r of the conventional process could be obtained, .~ - .
- , -~ - 11 -
from the bottom of the column for 20 minutes to back-wash and the separated upper layer of the resin SAlOAL was discharged . 20 through the upper resin transfer pipe at the position of 58 cm from the bottom and transferred to an anion regeneration.column. .
Second step: The mixed resins as the middle layer was discharged through the lower resin transfer pipe at the position of 48 cm from the bottom, Third step: The mixed resins as the middle layer discharged in the second step were sieved in the wet condition with a sieve at 297 ~ (3apanese Industrial Standard).
~ourth step: The resin transferred to the anion regeneration column and the residual resin the column were respectively regenerated with 4 liters of 4% aqueous solution of sodium hydroxide and 8 liters of 4% aqueous solution of sulfuric acid during 1 hour. Then, a deionized water was ~ 9 ,.
.... : . .: . ~ . . . . .......... . . .
108~)376 passed at a rate of 30 liter/hr. and 60 liter/hr, for 1 hour to wash the resins, Fifth step: The resin in the anion regeneration column obtained by regenerating and washing with water was fed into the main column and a compressed air was fed from the bottom of the column for 10 minutes to mix the regenerated anion and cation exchange resins.
Sixthstep: Water was filled to cover the resin and an aqueous solution containing 7.1 ppm of NaCQ (as CaCO3) and 1.52 ppm of ammonia (as CaCO3) at pH of 9.2 was passed at a rate of 300 liters/hr. for 4 hours. -Seventh step: The resins in the middle layer from which fine particles of the resins were removed in the third step were mixed with the resins in the column treated in the -, sixth step.
The first to seventh steps were repeated for five times. The total amount of the resins removed in the third step was 9.7 mQ.
Example 4 The anion and cation exchange resins of Example 3 were , used and water (pH of 9.2) prepared by adding 1.52 ppm (as CaCO3) of ammonia to a deionized water containing 0.02 ppm of sodium ions and an electric conductivity of less than 0.1 ~/cm, was fed at a rate of 300 liters/hr. After 150 hours, the deionized water treated had an electric conductivity of 0.14 ~v/cm and a concentraton of sodium ions of 2.3 ppb.
Reference 2 The first to seventh steps of Example 3 were modified as follows, In accordance with the conventional process, the anion exchange resin as the upper layer was discharged through the resin transfer pipe at the position of 53 cm from the bottom and the anion and cation exchange resins were regenerated -' ' ' : '' ' ~"': ~.. '''"' ' '' . ' '` :
-, ..
10~(~376 and mixed. Then, as the process of Example 3, the water containing ammonia was passed. After 150 hours, the deionized water treated had an electric conductivity of 0.21 ~v/cm and a concentration of sodium ions of 12 ppb.
First step: A deionized water was fed to flow in an upward current at a linear velocity of 10 m/hr. at 20 - 1C
for 20 minutes to back-wash and then, the resin in the upper layer was discharged through the resin transfer pipe at the ~; position of 53 cm from the bottom and transferred to the anion regeneration column.
Second and third steps: None.
Fourth, fifth and sixth steps: The treatments being the same with those of Example 3.
Seventh step: None.
, The deionized water obtained by the process of Example 4 had an electric conductivity of 0.14 ~/cm and a concentration of sodium ions of 2.3 ppb whereas in Reference 2 as the . conventional process, a deionized water had an electric conductivity of 0.21 ~/cm and a concentration of sodium ions of 12 ppb. In accordance with the present invention, the deionized water having a content of sodium ions 1/5,2 to that r of the conventional process could be obtained, .~ - .
- , -~ - 11 -
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for regenerations of an anion exchange resin and a cation exchange resin used for deionizing water in the form of a mixed resins, the improvement which comprises separating the anion exchange resin and the cation exchange resin as the upper and lower layers by back-washing the mixed resins with water and discharging a middle layer containing non-separated resins at the boundary between the upper and lower layers, and charging the discharged middle layer in a step before the back-washing step in a subsequent regeneration process.
2. A process according to Claim 1 wherein the mixed resins are separated in the back-washing step, the upper layer is discharged for the regeneration, the middle layer of the mixed resin is discharged and fed back in a step before the back-washing step in a following regeneration process, and the lower layer is regenerated.
3. A process according to Claim 1 wherein the mixed resin are separated in the back-washing step, the lower layer is discharged for the regeneration, the middle layer of the mixed resin is discharged and fed back in a step before the back-washing step in the next regeneration process and the upper layer is regenerated.
4. A process according to Claim 1, 2 or 3, wherein fine particles in the middle layer of the mixed resins are separated.
5. A process according to Claim 2, wherein the upper layer separated by the back-washing is discharged together with the upward flow in the back-washing step.
6. A process according to Claim 2, wherein the upper layer separated by the back-washing is sedimented and then, the upper layer is discharged through a pipe together with a downward flow.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA294,172A CA1080376A (en) | 1977-12-30 | 1977-12-30 | Process for regeneration of mixed anion and cation exchanged resins |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA294,172A CA1080376A (en) | 1977-12-30 | 1977-12-30 | Process for regeneration of mixed anion and cation exchanged resins |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1080376A true CA1080376A (en) | 1980-06-24 |
Family
ID=4110417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,172A Expired CA1080376A (en) | 1977-12-30 | 1977-12-30 | Process for regeneration of mixed anion and cation exchanged resins |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1080376A (en) |
-
1977
- 1977-12-30 CA CA294,172A patent/CA1080376A/en not_active Expired
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