Intelligent WCF regulation

The demand for ultra-pure water for production and cleaning purposes is not always constant. For this reason, the output from the production unit is normally sent to a storage tank. When this tank is full, the production plant is generally switched to circulation mode in order to prevent the possible growth of bacteria.

To improve the flow of water, while reducing the operating costs, there are three types of water production plants available from Christ, a member of the Christ Water Technology Group. The options are:

• regulation of the output;

• regulation of the WCF- (Water Conversion Factor);

• regulation of the level in the storage tank

With the first option the plant is designed so that its operation is individually matched to the user's requirements, which also permits the amount of waste water to be reduced by up to 33%. A prerequisite for this is that the plant runs continuously or in recirculation mode. The regulation of the output also permits energy savings, since the pump runs only at low speed.

The second option, the WCF regulation, offers the greatest savings for the user. By keeping the water conversion factor constant with reference to the raw water, it is possible to compensate for variations in the operating parameters and to ensure that the plant runs uniformly.

Combined with recirculation of the ultra-pure water, this option results in a maximum overall water conversion factor of up to 95%, depending on the inlet parameters.

An important factor here is the potential savings in the operating costs: compared with the original amount of waste water, a further 50% can be saved and the energy consumption is reduced to less than 50% of the normal operating power.

This option also reduces maintenance costs, since the lifetime of parts subject to wear is longer and the consumption of regenerating salt is reduced.

In addition, water flows continuously through the pipes between the treatment system and the storage tank and this is more likely to prevent microbiological contamination.

The third option for the regulation of Christ plants is the level at which the company decides to regulate, where the generation of pure water is controlled as a function of the level in the storage tank.

For this purpose, a sensor in the storage tank sends information to the central PLC controller, causing it to reduce automatically the system output to 70% of the maximum value. This permits uniform operation of the treatment system even in the case of extended production phases.