Danfoss iSave 21, Руководство пользователя

Страница: 40 / 106

Instruction Membrane cleaning of the RO-system with iSave unit
2
180R9214 / 521B1165 / DKCFN.PI.003.G2.02 / 03.2011
Membrane cleaning
Below procedures are general guidelines for the membrane cleaning of SWRO-systems with the
Danfoss iSave. Procedure details may differ depending on the system design.
The numbers marked in () refer to the diagram’s below.
The purpose of membrane cleaning is to reduce scaling and fouling in the membranes. For optimal
performance specific chemicals are required, depending on the cause of the contamination.
After chemical treatment the system must be flushed with fresh water. The flushing water, coming out
of the membranes, may consist of a large amount of suspended inorganic particles. It is important to
assure that these particles are not fed into the iSave.
NB! It is recommended to disconnect the piping from the “HP in” of the iSave and flush the con-
taminated water from the membranes directly to drain. By disconnecting the pipes there will be
no accumulation of contaminations in the HP-piping and HP-valves. See P&ID no 2.
The procedures below are based on Dow’s Cleaning and Sanitization: Cleaning steps described in
Dow’s Form No. 609-02090-1005. Other procedure may be used depending on the membranes used.
Below procedure is according P&ID no 1.
1. Stop the high-pressure pump (4), and stop the iSave (11).
2. Stop the seawater supply pump (1).
3. Close valve (9) and open valve (16).
4. Pump mixed cleaning solutions to the vessel at conditions of low flow rate and low pressure to
displace the process water. Use only enough pressure to compensate for the pressure drop from
feed to concentrate. The pressure should be low enough that essentially no or little permeate is
produced. A low pressure minimizes re-deposition of dirt on the membrane.
Dump the brine/concentrate to prevent dilution of the cleaning solution.
5. Recycle: After the process water is displaced, cleaning solution will be present in the concentrate/
brine stream. Recycle the cleaning solution from the piping to the cleaning solution tank.
6. Turn of the pump and allow the elements to soak.