Dow uses jet engines for power "We're witnessing a new dimension in industrial power production." That's how Dow Chemical's Leland A. Doan views the three jet-powered electricityand steam-generating units now coming into full operation at the company's Pittsburg, Calif., complex. It's the first time that jet engines have been used by a major U.S. chemical producer to generate its base-load power, says Mr. Doan, general manager of Dow's western division. The $5.2 million installation will supply the Pittsburg plant with up to 75% of its annual electricity requirements. And Mr. Doan intimates that additional units are on the way as power requirements at the plant grow. However, Dow will continue to buy some of its electricity and steam from Pacific Gas & Electric Co. A Pratt & Whitney Aircraft FT4 turbojet engine is at the heart of each
Dow's P&WA FT4 New dimension in industrial power
generating unit. Basically similar to the company's JT4 engine used to power jet aircraft, the FT4 operates on natural gas. It can deliver up to 30,000 hp. An expander turbine at the rear of the engine converts the hot exhaust gases—which normally push an aircraft forward—into shaft power directly coupled to an electric generator. While still at 750° F., the exhaust gases pass through coils in a boiler to produce steam. Each engine operating at full power generates 21,000 k w ( e ) . and 150,000 pounds of steam (at 150 p.s.i.g.) hourly. The first industrial application of an aircraft jet engine was in Columbia Gulf Transmission Co.'s natural gas pipeline compression station near 14 C&EN AUG. 8, 1966
Clements ville, Ky., that started up in 1960. The Columbia Gulf unit is based on a P&WA J57 engine that supplies power to a Cooper-Bessemer gas turbine compressor. Since then, 38 jet-powered units have gone into service in gas pipeline compressor stations. To date, these engines have accumulated more than 30,000 hours of operation. Phillips Petroleum uses a similar jet-power package in its helium plant at Dumas, Tex. A number of public utilities throughout the country have installed aircraft jet engines as auxiliary power sources for their heavy peak-load periods. P&WA points out that the Pittsburg installation is the first industrial use of a jet engine to produce on-site electricity and steam. From Dow's experience to date, the economics of the Pittsburg system are impressive. The aircraft gas turbine generates electricity at a heat rate of approximately 14,000 B.t.u. per kwh. But by taking credit for the 6000 B.t.u. per kwh. steam generation using the jet turbine's exhaust heat, the equivalent heat rate for generating electricity compares favorably with that of the largest and most efficient public utilities' steam turbine electricity plants in the country. These generate electricity at a heat rate of between 8000 and 8500 B.t.u. per kwh. Dow estimates that the jet-powered units cut its electricity cost by 25% and its steam cost by 10%. The company has the added advantage of taking natural gas from its Brazos Oil & Gas division gas wells at Brentwood, some 25 miles from Pittsburg. There are other advantages to the jet-engine route to power generation. The engines have chalked up a remarkable record for trouble-free performance in powering aircraft. When the JT4 engine was first used by commercial airlines in the late 50's, for example, the Federal Aviation Agency ruled that each engine must be overhauled after about 1200 hours of inservice operation. The rules have since changed. Today, some airlines operate the engine for 7000 hours and more between overhauls. Still another advantage is that a jet engine in a power plant can be removed and replaced in less than six hours. And it calls for only normal aircraft-type maintenance. Dow's move at Pittsburg is in line with the company's overall policy of expanding its own electricity- and steam-generating capabilities. At Freeport, the company's Texas division has installed two Westinghouse Electric W-301G supercharged gas turbines that can produce more than 64,000 k w ( e ) . under normal conditions. Dow Texas has ordered additional gas turbines.
Phosphate purge dooms algae Purely operational changes in several sewage plants have eliminated 90% of former pollution-feeding effluent phosphates, according to the Department of Interior. Secretary Stewart L. Udall hails the development as one that could lead to a major, early breakthrough in water algae control. The algae, called algal blooms, have grown increasingly fat on phosphates passing unchecked into rivers and lakes from large-scale waste-treatment plants. Interior cites conditions in the Potomac River below Washington, D.C., Lake Erie, and Lake Tahoe as examples of the tiny organism's work, which can result in a fish-killing condition. Efforts have been under way for years to stop the nourishing phosphate outflow (C&EN, March 28, page 43). Interior acknowledges that industry devotes considerable research and development energy to the algae problem. Nevertheless, Interior points out that phosphates, unlike most waste impurities, are still not removed by present treatment stations. Interior's method, which uses no added chemicals, is fast and relatively inexpensive, the department says. Its effect is to starve the algae by cutting off the phosphate supply. The actual means of control came to light during a data survey made last fall on three San Antonio, Tex., sewage plants by Interior's Water Pollution Control Administration. The review started as a routine progress check but sparked a special investigation when it turned up a remarkably low level of phosphates from one of the three plants. After four months of hunting by a team from WPCA's Robert S. Kerr Research Center in Ada, Okla. (under Dr. Leon Weinberger), suspected cause of the difference narrowed to several factors. Although all three of the secondary waste treatment plants used an activated sludge process, one operated differently from the others. (The activated sludge process involves settling, aeration, and bacteriological breakdown and assimilation of biological impurities.) Based on the odd plant, five features in one of the remaining plant's operation were changed. Specifically, the investigators boosted aeration and bacteria concentration, reduced settling time, shortened the duration of settled materials in the settling tank, and increased the ratio of bacteria to organic materials. With this adopted pattern, phosphate screening efficiency in the second plant shot up more than 90 Vc The Kerr team does not know what exactly brought about the improvement—
