Department of Microbiology, University of Hawaii at Manoa, Honolulu, Hawaii 96822.
Appl Environ Microbiol. 1986 Jun;51(6):1186-98. doi: 10.1128/aem.51.6.1186-1198.1986.
Countermeasures to biofouling in simulated ocean thermal energy conversion heat exchangers have been studied in single-pass flow systems, using cold deep and warm surface ocean waters off the island of Hawaii. Manual brushing of the loops after free fouling periods removed most of the biofouling material. However, over a 2-year period a tenacious film formed. Daily free passage of sponge rubber balls through the tubing only removed the loose surface biofouling layer and was inadequate as a countermeasure in both titanium and aluminum alloy tubes. Chlorination at 0.05, 0.07, and 0.10 mg liter for 1 h day lowered biofouling rates. Only at 0.10 mg liter was chlorine adequate over a 1-year period to keep film formation and heat transfer resistance from rising above the maximum tolerated values. Lower chlorination regimens led to the buildup of uneven or patchy films which produced increased flow turbulence. The result was lower heat transfer resistance values which did not correlate with the amount of biofouling. Surfaces which were let foul and then treated with intermittent or continuous chlorination at 0.10 mg of chlorine or less per liter were only partially or unevenly cleaned, although heat transfer measurements did not indicate that fact. It took continuous chlorination at 0.25 mg liter to bring the heat transfer resistance to zero and eliminate the fouling layer. Biofouling in deep cold seawater was much slower than in the warm surface waters. Tubing in one stainless-steel loop had a barely detectable fouling layer after 1 year in flow. With aluminum alloys sufficient corrosion and biofouling material accumulated to require that some fouling coutermeasure be used in long-term operation of an ocean thermal energy conversion plant.
在夏威夷岛附近的单一流经系统中，使用冷深海水和暖表面海水，对模拟海洋热能转换热交换器中的生物污垢对策进行了研究。在自由结垢期后，手动刷洗回路可去除大部分生物污垢物质。然而，在 2 年的时间里，形成了一层顽固的薄膜。海绵橡胶球每天通过管道自由通过只能去除松散的表面生物污垢层，并且在钛和铝合金管中都不足以作为对策。每天用 0.05、0.07 和 0.10 mg 升的氯处理 1 小时可降低生物污垢率。只有在 0.10 mg 升的氯处理 1 年以上，才能防止薄膜形成和传热阻力升高到不可接受的水平。较低的氯化处理方案导致形成不均匀或块状的薄膜，从而产生更大的流动湍流。结果是传热阻力值降低，与生物污垢量无关。让污垢形成，然后用 0.10 毫克/升或更低的氯进行间歇性或连续氯化处理的表面仅得到部分或不均匀的清洁，尽管传热测量没有表明这一点。需要连续氯化处理，用 0.25 mg 升的氯才能将传热阻力降至零并消除污垢层。深海冷水中的生物污垢比暖表面水中慢得多。在流动中 1 年后，不锈钢管道中的一个回路几乎没有检测到污垢层。对于铝合金，由于腐蚀和生物污垢物质的积累足以在海洋热能转换装置的长期运行中使用某种污垢对策。
