Claims:WE CLAIM:
1. A method of cleaning of EDI system comprising steps of:
A permeate header valve (13) connected to a DM Water storage Tank (14) is kept closed;
An EDI Skid (A), operating in good condition is started;
An EDI Feed Pump (3) is started and Valve (9) & Valve (12) are opened;
Valve (8) and Valve (13) remains closed;
DM Water from said DM water storage tank (14) is generated and diverted to EDI skid (B) having high fouling;
The DM water is introduced from the permeate side of said EDI skid (B) through valve (11);
An outlet valve (6) is opened and valve (7) remains closed;and
The outlet effluent from said EDI skid (B) is discharged out through said outlet valve (6) & is finally drained out through valve (1);

2. The method of cleaning EDI system as claimed in claim 1 wherein said circulation/backwash is carried out for thirty minutes and the parameters for the inlet DM water and backwashed water are monitored at an interval of 10 minutes.

3. The method of cleaning EDI system as claimed in claim 1 whereinno additional arrangement in the form of piping for carrying the cleaning procedure is required.
, Description:FIELD OF THE INVENTION
[001] The present invention relates to troubleshooting of EDI (Electro Deionization) System. The present invention particularly relates to a method for carrying out cleaning of the EDI Skids which are used for generation of DM water for Boiler Requirements.

[002] More particularly, the present Invention relates to a method involving cleaning of EDI system without utilizing Cleaning Chemicals.
BACKGROUND OF THE INVENTION
[003] High purity water production has traditionally used a combination of membrane separation and ion exchange processes. EDI is a process which combines semi-impermeable membrane technology with ion-exchange media to provide a high efficiency demineralization process.

[004] Electro dialysis employ electrical current and specially-prepared membranes which are semi permeable to ions based on their charge, electrical current, and ability to reduce the ions based to their charge. Through electro dialysis an electrical potential transports and segregates charged aqueous species. The electrical current is used to continuously regenerate the resin, eliminating the need for periodical regeneration.
[005] The EDI process produces industrial process water of very high purity, using less than 95% of the chemical products used in the conventional ion exchange processes. With EDI system membranes and electricity replace chemicals that the old processes required daily.

[006] Normally with continuous operation of EDI system over the period of time, the EDI skids in the EDI system gets fouled leading to decrease in permeate generation / high Feed pressure.

[007] Normally chemical cleaning process is involved in case the EDI system gets fouled or the above mentioned issues happen. However for the invented process normal DM water will be used to clean the EDI system.
[008] The major advantages of the invented process will be as follows:
1) No chemicals will be required as in conventional process.
2) The outlet effluent will be easily disposed of without any addition of chemicals.
OBJECTS OF THE INVENTION
[009] It is therefore, an object of the present invention to propose a method for cleaning of the EDI system without involvement of chemicals.

[0010] A further object of the Invention is to propose a method which is easy to carry out maintenance of the EDI system without any additional arrangement in the form of piping etc.
SUMMARY OF THE INVENTION
[0011] Accordingly, there is provided a method for carrying out cleaning of the EDI system without utilizing cleaning chemicals. Normally high pH, Low pH chemicals are used for cleaning the EDI system in case of High fouling etc.

[0012] The EDI systems are now being used in the power plants for generation of DM water which as an essential requirement for boiler.

[0013] Whenever EDI system gets fouled, high pH / Low pH chemicals are used for cleaning the EDI system. In the present invention, a novel methodology to clean the EDI system without usage of cleaning chemicals & any other additional arrangement is proposed.
BRIEF DESCRIPTIONS OF THE ACCOMPANYING DRAWINGS
[0014] Figure 1 - Shows a schematic representation of the method and device for carrying out the present invention.
DETAIL DESCRIPTION OF THE INVENTION
[0015] The present invention will be described in detail below with reference to an embodiment as shown in the drawing.

[0016] Referring to Fig. 1, the common EDI skids (A, B & C), permeate header valve (13) are connected to DM Water storage Tank (14) will be kept closed.
[0017] The EDI Skid (A) which is operating in good condition is started and the discharge valve (2) along with one of the EDI Feed Pumps (3) is opened & simultaneously Valve (9) & Valve (12) are opened & Valves (8) and (13) remain closed. The DM Water is generated from DM water storage tank (14) and diverted to EDI skid (B) having high fouling. The DM water is introduced from the permeate side of the EDI skid (B) having high fouling through valve (11) & valve (6) is opened & valve (7) remains closed. The outlet effluent from the EDI skid (B) is discharged out through the outlet valve (6) & finally drained out through valve (1).

[0018] The above circulation/backwash is carried out for thirty minutes and the parameters for the inlet DM water and backwashed water to be monitored at an interval of 10 minutes. The DM water has a conductivity of less than 0.1 micro Siemens/cm and the effluent water quality has conductivity of nearly (6-8) micro Siemens/cm during starting of cleaning. After completion of the cycle, the quality of feed DM water becomes equivalent to effluent outlet water, implying complete cleaning of the EDI skid and removal of fouling elements. During cleaning the Feed Inlet Valve(5), the permeate outlet valve (10) and the Valve(4) of the EID Skid(C) remains closed till the cleaning process gets completed.

[0019] Thereafter the skid can be taken into operation.