Promotion of drop-by-drop condensation of steam from seawater on a vertical copper tube
✍ Scribed by L. A. Bromley; J. W. Porter; S. M. Read
- Publisher
- American Institute of Chemical Engineers
- Year
- 1968
- Tongue
- English
- Weight
- 668 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0001-1541
No coin nor oath required. For personal study only.
✦ Synopsis
A limited number of tests were made of promoters, their method of application, corrosion resistance, etc.
The best promoter found to date is tetrakis octadecyl thio silane ( C I ~H ~~S ) & which differs only in parafinic chain length from (Ci2H25S)4Si which was found to be one of the best promoters for drop-by-drop condensation by Blackman and Dewar ( I , 2), Hampson (2, 3), and Osment (4, 5). These compounds are nontoxic.
The cis compound appears to be superior to the Ciz compound in that it is less volatile, lower melting (-34"C), and appears to impart superior oxidation resistance to copper when adsorbed on clean oxide-free metal.
Copper tubes can be rapidly cleaned in place by sulfur dioxide or hydrochloric acid in steam, or, i f previously promoted by a thio silane, by treatment first with chlorine gas in steam.
The thio silanes may be rapidly applied as a 1% solution in octanoic acid injected into the sea-water feed. The ocid octs as cleaner and poor promoter, allowing the good promoter molecules to contact the metal tube.
The amounts of the best promoters required are in the parts per billion range.
* This value i F at a reduced hut more nearly typical flux of -14.000 B.t u./(hr.) (hq. ft.). The film type coefficient is c 900.
O * The procedure involving cleaning with sulfur dioxide with short bur& of chlorine and direct addition of about 1 ml. of 1% thio silane in octanoic acid was repeated many times with the same resolt. Oxygen must be kept a vay from the tube after cleaning and before promotion or the promoter will deposit on the oxide, resulting mainly in poor promoter life and decreased widation resistance. Traces of chlorine must not be allowed to contact the promoted tube or the promoter will be patially removed and oxidation will proceed.