Industrial Water Filtration applications in a Power Generation facility



In a non-renewable Electric Power Generation facility there are many different water streams each demanding its own specific level of water purity. The presence, flows and purity of each of these streams is driven by the plant design, e.g. coal fired, combined cycle, gas-turbine, geo-thermal or nuclear.

These can include:

– Pre-treatment of well, surface or city water

– Boiler water make-up

– Cooling tower

– Service water

– Flue gas desulfurization

– Ash handling

– Coal pile run-off

– Gas turbine inlet air cooling/fogging

– Waste water disposal.

Regardless of the application, there is a good chance that some type of water filtration will be required in order for the power generation application to operate at its peak efficiency.

Defining the Types of Water Filtration

Water filtration options in the Power Generation industry can be divided into two major categories, based upon the filtering media used

– granular and

– membrane.

Granular water filtration has been used for many decades in the Power Generation industry, and will be familiar to most. Examples of granular media filtration include sand filters; activated carbon filters for taste, odor, and chlorine removal; anthracite filters; and fine garnet filters.

These types of filters can remove suspended particles down to about 10 microns in diameter. With the use of certain coagulant or flocculant polymers fed prior to these filters (fed as filter aids), some success has been seen in the removal of particles down to almost 1 micron.

The spacing between the discrete filtering media particles serves as the pores. Suspended solids trapped out by these filters will be collected on top of the filtration media bed, or within the pores.

Membrane water filtration uses membranes to remove suspended particles. Unlike granular filters, the membranes are designed with pores and are capable of removing much smaller particles. The ultimate membrane filtration is reverse osmosis (RO), where dissolved solids (metal ions) can be removed. This is not really a filtration mechanism in the truest sense of the words, as the semi-permeable membranes used in RO do not have pores. It is more properly thought of as a demineralization mechanism.

Membrane water filtration is best characterized by the size range of the filterable particles, as follows:

1. Microfiltration (MF) - can include woven or wound depth-type cartridge filters, or true membrane filters. Can remove particles from about 0.1 micron to over 1 micron.

2. Ultrafiltration (UF) – can remove particles from below 0.01 microns to over 0.1 microns. Can remove some large molecular weight organic dissolved material.

3. Nanofiltration (NF) – can remove particles from below 0.001 microns to 0.01 microns. Can remove smaller molecular weight organics.

4. RO – can remove particles from 0.0001 microns to 0.001 microns. Can also remove DISSOLVED IONIC SOLIDS.

As a leader in the development of water resources, Layne Christensen Company is also committed to developing high purity water solutions for the Power Generation industry.

The Research & Development team of our Water Treatment Division focuses on refining and expanding the water treatment methods we currently employ.

The science of water treatment is dynamic, and optimum solutions are unique to each situation. Layne Christensen Company engineers have the experience, innovation and commitment to evaluate and deliver effective, efficient water treatment solutions for your situation.