GB1562147A

GB1562147A - Method of regenerating of ion exchange material

Info

Publication number: GB1562147A
Application number: GB21406/77A
Authority: GB
Original assignee: Northern Engineering Industries PLC
Current assignee: Rolls Royce Power Engineering PLC
Priority date: 1978-03-23
Filing date: 1978-03-23
Publication date: 1980-03-05

Description

(54) METHOD OF REGENERATING OF ION EXCHANGE MATERIAL (71) We, NORTHERN ENGINEER ING INDUSTRIES LIMITED, a British Company of Nei House, Regent Centre, Newcastle-upon-Tyne, NE3 3SB do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to methods of regenerating ion exchange materials.

A method of regenerating mixed bed ion exchange materials according to the invention comprises separating the materials into an upper main anion layer and a lower main cation layer and transferring the anion material with entrained contaminant cation material to an anion regeneration vessel, separating the entrained cation material into a minor layer at the bottom of the anion regeneration vessel by a flow of water, removing the contaminant cation material together with some anion material by means of a flow of water, regenerating the anion material in the anion regeneration vessel and regenerating the main cation material layer, transferring the regenerated anion material from the anion regeneration vessel back to the main cation layer and mixing the regenerated materials.

The contaminant cation material is preferably passed to a small hold vessel and held there until it can be added to the next charge of mixed materials before they are separated into main layers.

Alternatively, the contaminant cation material may be directly returned to main layer of cation material before the main layer is regenerated.

The method is preferably performed using apparatus which comprises a first vessel in which separation of the materials into main layers occurs and in which regeneration of the main cation layer occurs, and a second vessel, the anion regeneration vessel, in which regeneration of anion material occurs and in which the contaminant cation material is separated out as a minor layer.

Preferably, both vessels have cone-shaped bases to assist removal of material from the vessels at their bases.

The apparatus may comprise a holding vessel smaller than the first and second vessels to which contaminant cation material can be transferred.

The first and second vessels each have a screen in the lower part of the vessel to retain material thereon but to permit liquid to pass therethrough.

One form of method and apparatus will now be described by way of example to illustrate the invention with reference to the drawing accompanying the provisional specification which is a schematic diagram showing the apparatus.

The drawing shows a regeneration station comprising a separation and cation regeneration vessel 1 and an anion regeneration vessel 2. In addition a small holding vessel 3 is provided. When the resin materials in a service unit (not shown) require regeneration they are transferred to the separator and cation regeneration vessel 1 via the conduit 10 and backwash water is admitted via the conduit 11. This classifies the materials and the anion resin forms an upper layer. The materials have different densities so that they are classified by backwashing with water.

Sluicing water is admitted via the conduit 12 with a downward flow of transfer water via the conduit and its valve at 13. The anion resin is conveyed via the pipe 14 into the anion regeneration vessel 2. This operation is imperfect and some contaminant cation resin is transferred with the anion resin. The next operation is to backwash the anion resin by admitting water at 15, which leaves the anion regeneration vessel at 16. This separates the entrained contaminant cation resin into the cone-shaped base of the anion regeneration vessel 2. When the contaminant cation resin has collected at the bottom of the cone it is removed by hydraulic conveyance using water prior to the introduction of the anion resin regenerant. There are several methods of removing the contaminant cation resin from the base of the unit. Firstly, an upward flow of water can be introduced into the ves sel 2 @@@ the conduit 15 and this conveys the resin at the base of the vessel out of the conduit 17. Alternatively, water can be introduced via the conduit 18 to displace the cation resin from the bottom of the cone. The third alternative is to introduce water at 15 and 18. A fourth alternative is to introduce water at 15 the majority of which conveys resin out of 17 and the remainder flows upward through the anion resin keeping it slightly fluidised and leaves the vessel via the backwash outlet 16. The contaminant cation resin removed from the base of the vessel 2 along with some anion resin can be conveyed directly to the vessel 1, in which case the contaminant cation material is regenerated along with the main cation layer, alternatively the contaminant cation material can be discharged into the holding vessel 3. The cation material is held in the vessel 3 until it can be mixed with the next charge of mixed resin materials to be regenerated before they are separated into layers in the vessel 1. This avoids wastage of regenerant acid in converting the anion material (mixed with the contaminant cation material) into sulphate form, which occurs if the first mentioned option is adopted.

The anion resin freed from contaminant cation resin can now be regenerated with a downward flow of sodium hydroxide after which it is rinsed free of excess regenerant.

The cation resin in the vessel 1 is regenerated with a downward flow of regenerant acid after which it is rinsed. The anion resin is then transferred from the vessel 2 into the vessel 1 where the two resins are thoroughly mixed by air blowing. A final rinse is given to the mixed resins after which they are ready for transfer back to the service unit through the outlet 26 transfer water being admitted at 35.

The fact that cation resin was not allowed to be present in the anion resin during the time of the passage of the sodium hydroxide regenerant ensures that the regenerated cation resin is free from beads of resin which are substantially in the sodium form. The quality of the water produced in the subse quent treatment cycle is thereby improved.

An additional feature of the present inven- tion is the addition of a quantity of inert material with a particle size and density which makes it form an intermediate layer between the main cation and the anion resin layers. The advantages of the use of an inert material of correct particle size and density is that it reduces the amount of anion resin which has to be taken out of the vessel 2 to ensure complete removal of the cation resin.

In the drawing the vessel 1 has an air outlet and valve at 20, a regenerant and rinse water inlet and valve at 22 leading to a distribution system 24 in the vessel; a resin outlet and valve at 26; a screen at 28; an air inlet and valve at 30; an outlet and valve for spent regenerant and rinse water at 32; a backwash outlet and valve at 34; and a backwash and resin transfer water inlet and valve at 35 connected to the conduit 11.

The vessel 2 has an air outlet and valve at 36; a regenerant and rinse water inlet and valve at 38; and anion resin inlet and valve at 40 connected to the conduit 14; a screen 42 in the vessel; an air inlet and valve 44; a spent regenerant and rinse water outlet and valve at 46; a backwash and -transfer water inlet and valve 48 connected to the conduit 15; and a resin outlet and valve 50 connected to the conduit 17.

The conduit 17 is connected to an inlet and valve 52 at the vessel 3. A by-pass and valve 54 is provided too. The vessel 3 has a transfer water inlet and valve 56; and an outlet with valve 58.

Attention is drawn to our co-pending application No. 52990/76 (Ser. No.

1535443) which describes a method of treat ing water in which the ion exchange materials are regenerated after separation and in which an inert material is used.

Claims

WHAT WE CLAIM IS:

1. A method of regenerating mixed bed ion exchange materials comprising separat ing the materials into an upper main anion layer and a lower main cation layer and trans- ferring the anion material with entrained contaminant cation material to an anion regeneration vessel, separating the entrained cation material into a minor layer at the bot tom of the anion regeneration vessel by a flow of water, removing the contaminant cation material together with some anion material by means of a flow of water, regenerating the anion material in the anion regeneration vessel and regenerating the main cation material layer, transferring the regenerating anion material from the anion regeneration vessel back to the main cation layer and mixing the regenerated materials.

2. A method according to claim 1, in which the contaminant cation material is pas- sed to a hold vessel and held there until it can be added to the next charge of mixed materi als before they are separated into main layers.

3. A method according to claim 1, in which the contaminant cation material is pas sed directly to the main cation layer before the main cation layer is regenerated.

4. A method according to any preceding claim, in which the materials include a quan tity of inert material having a particle size and density such that it forms an intermediate layer between the main cation and anion layers.

5. The method according to claim 1 when performed using apparatus comprising a first vessel in which separation of the materials into main layers occurs and in which regeneration of the main cation layer occurs, and a second vessel, the anion regeneration vessel, in which regeneration of anion material occurs and in which the contaminant cation material is separated out as a minor layer, each vessel having a screen in the lower part of the vessel to retain material therein but to permit liquid to pass therethrough.

6. The method according to claim 5, in which both vessels have cone-shaped bases.

7. The method according to claim 5 or claim 6, comprising a holding vessel to which contaminant cation material can be transfereed.

8. A method of regenerating ion exchange materials substantially as hereinbefore described with reference to the drawing accompanying the provisional specification.