March 14, 2006
Kurita Water Industries Develops the "OXYNON™MF series", which Restrains
Corrosion Thinning of Feedwater and Condensate System Pipes in Boilers
Kurita Water Industries Ltd. (HQ: Shinjuku-ku, Tokyo, President: Hiroshi Fujino) has developed the "OXYNON™MF series" water treatment agents designed to decrease wall thinning caused by corrosion in pipes and equipment for feedwater and condensate systems in deionized feedwater boilers.
1. Development background
Recently, we have received reports citing numerous cases in which pipes in feedwater and condensate systems had to be replaced due to the thinning of the inner walls. Also these reports have shown problems in boiler feedwater system pipes in middle/high pressure power boilers, which are fed with mixed water comprising of deionized makeup water and steam condensate, as well as in low pressure systems for multiple pressure steam generators for gas turbine combined cycle power plants that are used extensively in newly constructed power generating units. Damage in feedwater pipes or feedwater heaters caused by thinning may cause boilers to shutdown, which could result in serious accidents, injuries or factory shutdown.
There are two major causes for thinning: physical factors such as water turbulent and fast waterflow within pipes and chemical factors (corrosion) related to existing dissolved oxygen in the water and incorrect pH control. Even if oxygen is successfully removed from the feedwater to prevent heavy corrosion, which can be severe enough to create pitting in pipes in a short period of time, stable corrosion prevention iron oxide films are less likely to form since pure water with a neutral pH level would increase the solubility of iron oxides on the inner wall surfaces that have direct contact with water. Water turbulent and fast waterflow conditions result in circumstances where iron oxides, together with underlying metals, dissolve in water instigating thinning to progress further.
Furthermore, recently, there has been close attention paid to water "temperature" as a factor for thinning due to corrosion. New research has shown that thinning is more likely to develop when feedwater is within the temperature range of 90 to 180 degrees C, in particular 130 to 150 degrees C. It is believed that this is because the aforementioned iron oxides might reach the highest point of solubility in this range. In power generating boilers, feedwater is usually heated and the temperature crosses this range. Additionally, in the case of exhaust gas heat recovery multi-pressure steam generators (*) used in gas turbine combined cycle power plants, operation temperatures of low pressure boilers in plants are often set at approximately 130 to 150 degrees C, which will likely result in thinning. Moreover, due to structural limitations, there are several circumstances in which usage of solid alkalis like sodium phosphate is avoided and only volatile alkalis such as ammonia and neutralizing amines are used to increase pH levels in the feedwater and boiler water. Ammonia and some neutralizing amines do not maintain proper pH levels and tend to produce favorable environments to the development of thinning.
- (*)A single unit features boilers with multiple operation pressure levels (high/middle/low) and operation temperatures. It generates steam to drive steam turbines by recovering residual heat from high temperature exhaust gases generated by gas turbines, and improves the heat efficiency of entire power plants.
2. "OXYNON™MF series"
Kurita has been marketing the "OXYNON™M series" as water treatment agents that decrease corrosion in boiler feedwater and condensate systems. The "OXYNON™M series" is a corrosion inhibitor for feedwater and condensate systems and are mainly comprised of some neutralizing amines to prevent the pH decrease of feedwater and condensate water. By improving the performance in pH decrease prevention of the "OXYNOM™M series", we have developed the new "OXYNON™MF series". From among neutralizing amines to prevent the pH decrease of feedwater and condensate water, Kurita has selected those neutralizing amines that can produce the highest increase in pH level within the temperature range where thinning is most likely to occur, then blend it as a base compound.
<OXYNON™MF series features>
- 1)Set to produce the highest increase in pH level within the temperature range where thinning is most likely to occur.
- 2)Improves corrosion prevention performance by stabilizing iron oxide films on pipes' inner walls where water makes direct contact.
- 3)High thermal stability under high temperature conditions minimizes influence on the quality of feedwater, condensate and boiler water.
3. Our target market
Kurita has estimated that the market for water treatment agents that decrease the corrosion of feedwater and condensate system pipes in boilers will be approximately five billion yen and the market in which the "OXYNON™MF series" is applicable to, will be approximately one billion yen. Annual sales of the series in FY2006 are expected to reach 100 million yen.
4. Our future business
Kurita has helped our customers to realize stable operations and productivity improvement by providing various product lines of water treatment agents and equipment to prevent problems such as corrosion and scale in entire boiler facilities including: boilers, steam pipes, etc. Today, steam production cost has increased in response to the rise in fuel oil prices. The framework of designated energy management factories has changed, and stricter regulations such as the revision of the "Law concerning the Rational Use of Energy (Energy Conservation Law)" have been introduced. Accordingly, our customers are taking various measures to cut fuel costs, conserve energy, and reduce CO2 emissions. As a result, water treatment and water quality control in boilers have become more and more demanding.
We are determined to continuously help our customers to solve future problems by providing technologies and services to optimize boiler facilities along with developing new products like the "OXYNON™MF series".