Power Generation and Condensate Polishing

In many areas around the world, where water resources are scarce or require reuse, it's advocated that technology be used to treat industrial process water. For example, in the arid regions of China, the National Development and Reform Commission (NDRC) advocates all newly built coal-fired power plants adopt "pollution" control technology. As a result, use of powdered-resin condensate polishing systems has become widely prevalent in recovery and recycling of the return condensate stream on the steam condensate loop in industrial power generation systems. Careful purification of this stream to remove contaminants greatly reduces operating costs and can prevent damage to the system that's typically manifested via corrosion or steam leaks.

Features of powdered-resin filtration systems include:
large operating capacity;
effective removal of organic matter and colloid silicate;
effective removal of corrosion products from the thermodynamic system;
ferric oxide removal rates of 95% or higher.

These systems utilize powdered resins capable of achieving high regeneration rates. They're typically precoated onto the surface of fiber filter elements and also have the ability to act as both ultrafiltration and ion exchange systems.

Advantages powdered-resin condensate polishing filtration systems have over high-speed, mixed-bed filtration systems, for example, include:
minimal space requirement;
reduced capital investment;
reduced operating cost;
and simple system operation for ease of use and maintenance.

Condensate polishing normally applies to the treatment of condensed steam from turbines operating in the power industry. It can also be applied to condensed steam from any steam system being returned to the boiler. The ultimate goal of condensate polishing is to remove all soluble impurites and protect the high pressure boilers.

These contaminents can come from many sources:
1. Cooling water from condenser in-leakage and this can be a particularly severe problem where seawater cooling is employed.
2. Make-up water, this can arise from maloperation such that regeneration chemicals enter the system, plant over-run during the service cycle or complete removal of certain substances such as organic matter may not occur.
3. The conditioning chemicals used to protect the circuit e.g. ammonia, morpholine and hydrazine can be regarded as sources of contamination if they are to be removed by the condensate purification plant.
4. Insoluble impurities will usually be the corrosion products from the materials in the system with copper and iron are the predominant species.