Surface condensers turbine drives

There are three potential types of OTEC power plants opcii-cyclc, closed-cycle, and hybrid systems. Open-cycle OTEC systems exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface water into steam in a partial vacuum, and then use this steam to drive a large turbine connected to an electrical generator. Cold water piped up from deep below the oceans surface condenses the steam. Unlike the initial ocean water, the condensed steam is desalinated (free of salt) and may be collected and used for drinking or irrigation. 

A surface condenser condensing the steam from a process turbine drive operates at 1.0 in. Hg abs. The condensing load is 85,000 Ibs/hr steam. WTat is the capacity of the ejector ... 

A design of turbine whereby the driving force is provided by exhaust steam condensing in a surface condenser. 

Steam used to drive a turbine can be extracted at an intermediate pressure, for further use of the low-pressure steam. Rarely is the steam vented to the atmosphere, as this wastes steam, and the condensate is also lost. Many turbines exhaust steam, under vacuum, to a surface condenser. The lower the pressure in the surface condenser, the greater the amount of work that can be extracted from each pound of steam (see Chap. 17). 

Untreated water from the Columbia River was supplied as coolant to the dump condensers, as well as to the reactor coolant pump drive turbine surface condensers and the local turbine generator condenser. This condenser cooling water was then returned to the river. Untreated water was also supplied to the water treatment facility for the filtered water, sanitary water, and demineralized water systems (see Figure 3-16). The entire untreated water system was supplied by four pumps each with a capacity of 400,000 L/mln (105,000 gal/min). Water was supplied from the 181-N river pumphouse to points of process use through two separate headers (WHC 1989a). 

Surface condensers are used in conjunction with condensing steam turbines that drive large centrifugal compressors. As depicted in Exhibit 4-25 the exhaust steam enters the top of the condenser and passes through the shell, which is filled with tubes. Cold water is pumped through the tubes while hot exhaust steam passes around the outside. Hot water, called condensate, results and collects in the hot well at the bottom of die condenser. 

There are two basic types closed-cycle and open-cycle. In a closed-cycle system, warm surface seawater and cold deep seawater are used to vaporize and condense the working fluid such as ammonia, which then drives the turbine generator in a closed loop. In an open-cycle system, surface seawater is flash-evaporated in a vacuum chamber, and the resulting low-pressure steam drives a turbine-generator. Cold seawater is then used to condense the steam after it has passed through the turbine. The open cycle, therefore, can be configured to produce fresh water as well as electricity. 

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