用于电力行业的离子交换树脂

Thanks to its high specific heat capacity, water is an excellent heat exchanger. Steam is an effective energy carrier. These properties are utilized in water-steam circuits in numerous industrial processes. Depending on the quality of the feed water used in such cycles, this may require desalination or softening beforehand. 

Steam boiler manufacturers provide detailed specifications for feed water based on VGB guidelines (e.g. max. electrical conductivity; silicic acid, sodium and organic compound content) in order to ensure optimal operation. For example, forced-circulation boilers that work under high pressures of up to 290 bar and at hot steam temperatures of 600 °C require very pure, desalinated water. This is the only way to prevent turbines, for example, from becoming corroded, contaminated, or damaged or to avoid deposits forming there. 
 
The usual sources for feed water are well or surface water, reused waste water, and seawater. This variety makes clear that the treatment steps also need to be configured individually. Our LewaPlus^® design software is suitable for this.

In the course of producing make-up water, it is also important to reduce dissolved organic carbon (total organic carbon, TOC) with the aid of ion exchangers. This is necessary in order to counteract the formation of carbon dioxide or organic acids and thereby a lowering of the pH value in the condensate circuit, for example, which would otherwise promote corrosion. Depending on the type of the organic impurities in the untreated water, various procedures are suitable for this. The same applies to treating the ion exchangers used. Specially optimized resins are characterized by very low TOC emissions, and therefore only make a minimal contribution to the occurrence of TOCs themselves.

In most cases, the make-up water is conditioned with ammonia in the water-steam circuit in order to create an alkaline environment, which aids corrosion protection. Nonetheless, impurities are created during operation in a water-steam circuit, which for the most part find their way into the condensate in the form of ions.

Moreover, even very small cooling water leaks can allow the ingress of inorganic salts and organic compounds that then increase the risk of corrosion or lead to foaming under the extreme pressure and temperature conditions in the boiler. Therefore, treatment with ion exchangers is sensible or necessary in many cases in order to ensure reuse of the condensate as make-up water.

The ion exchange resins from the Lewatit^® KR series stand out thanks to their particularly high degree of regeneration and boast particularly good mechanical, chemical and osmotic stability.

Their monodispersity with a very low fines content creates the conditions for very low pressure losses compared with heterodisperse standard ion exchangers. When used in radioactive water circuits, they perform a variety of tasks and produce a water quality that can meet all the requirements of the nuclear power industry. Thanks to their outstanding hydraulic properties, these resins allow particularly high flow rates.

In nuclear power plants, ion exchangers are important components in the chemical and volume control system (CVCS). CVCS controls aspects including the boric acid content in the water of the primary circuit. Since ¹⁰B is a highly effective neutron absorber, its concentration has a direct effect on reactor performance. 

High-purity ion exchanger mixed beds containing cation exchangers partially preloaded with ⁷Li serve as purification filters. Together with initially Li-free depletion filters that are connected in parallel and absorb the ⁷Li that was also produced from boron in the reactor process as a result of neutron capture (coordinated B-Li mode of operation), they ensure a largely constant concentration of lithium hydroxide that acts as an alkalization agent.