1. Quality requirements of boiler feeding water
It is necessary to use qualified feeding water for safety, economic, reliable and stable operation of boiler and production of acceptable steam and hot water.
Substandard boiler feeding water will result in boiler scale. Additionally, metal on heating surface will be damaged due to high temperature, which reduces the thermal efficiency, increase the frequency of chemical cleaning and metal corrosion on the boiler. Besides, azeotropy of steam and water caused by high salt content in boiler water will result in deterioration of steam quality.
2. Water treatment proposals for boiler feeding water:
2.1 Proposals for softening water or softening dealkalization water
2.1.1 Softening by sodium ion exchange
Pretreatment → highly acid sodium positive ion exchange → deoxidization by heating power
It can ensure the residual hardness of water to be 0.03mmol/L, but will not reduce water alkalinity. It is applicable for low pressure boiler feeding water.
2.1.2 Softening dealkalization by sodium ion exchange
Pretreatment → hydrogen positive ion exchange → highly acid sodium positive ion exchange → deoxidization by heating power
Advantage: it can not only reduce water hardness but also reduce its alkalinity.
2.2 Proposals for saltwater treatment
2.2.1 Desalinization by composite ion exchange
Pretreatment → highly acid positive ion exchanger → carbon dioxide remover → highly acid sodium negative ion exchange → deoxidization by heating power.
Electric conductivity of produced water is generally less than 10μs/cm, applicable for medium and low pressure boiler feeding water.
Advantage: lower nonrecurring investment cost.
Disadvantage: a great amount of acid and alkalis reclaiming agents are required during operation, which causes increased costs and is inclined to bring pollution to the environment.
2.2.2 Desalinization by reverse osmosis
Raw water → multi-media mechanical filter → active carbon filter → fine filter → reverse osmosis device → deoxidization by heating power
The ratio of desalinization can reach more than 98%, applicable for medium pressure boiler.
Advantage: it can remove various sundries in water. No acid or alkalis reclaiming agent is used during operation. It needs low operating cost, and has no environmental pollution, easy for automatic control and reducing labor intensity.
Disadvantage: higher nonrecurring investment cost.
2.2.3 Desalinization by composite bed (or reverse osmosis) + mixed bed
Raw water → multi-media mechanical filter → active carbon filter → fine filter → reverse osmosis or composite bed → mixed bed → deoxidization by heating power
Salt in water is almost removed completely, applicable for medium and high pressure boiler.
Pre-desalinization by reverse osmosis prior to the mixed bed enhances the operation cycle of the mixed bed greatly in particular. Besides, the reverse osmosis device has removed the various sundries in water, which protects the mixed bed resin and prolongs its service life.
3. Product specification: 0.5m3/h～250m3/h
Water quality standard
It conforms to national or industrial boiler feeding water standard. （GB1576－79、DL/T561-95）
