Preliminary Design of A10 MWE OTEC Power Plant and 50 MWE OTEC Power Modules

ABSTRACT Preliminary designs for a 10 MWe Modular Application OTEC Power System and 50 MWe OTEC Power System Modules are discussed. The power systems are based on optimized closed ammonia cycles. Features of major plant components and working fluid, warm and cold water, and pl ant control systems are presented. Heat exchanger design allows manufacture of sub-elements in efficient shops equipped with modern automated drilling and tube assembly machinery. Elements can be rail-shipped to the platform outfitting site. All are within the lift capabilities of several candidate shipbuilding facilities. Both 10 MWe and 50 MWe power modules can be arranged so as to be compatible with any of the platform configurations under consideration for experimental and prototype OTEC plants up to 400 MWe capacity. INTRODUCTION The 10 MWe modular application OTEC power system and 50 MWe OTEC power system module preliminary designs discussed in this paper were developed by the Power Generation Division of the Westinghouse Electric Corporation under contract to the Division of Solar Technology, Department of Energy. Westinghouse was supported in its work by Carnegie-Mellon University in the areas of advanced heat exchanger technology and control system dynamic modeling; by Union Carbide Corporation also in the area of heat exchanger technology and with tube enhancement techniques; by Middle South Services. Inc., in the areas of electric utility practices and operating procedures; by Dr. A. E. Bergles with tube enhancement techniques; and by Gibbs and Hill, Inc. with total power plant integration. The 50 Mwe power system module preliminary design is a development of conceptual designs made by Westing house of a 100 MWe demonstration OTEC power plant in a ship-type platform. Cost studies of the conceptual designs showed that minimum total system (power plant plus platform) cost would be achieved with 50 MWe power system modules. Each module is an independent system consisting of one evaporator. one turbine and generator, one condenser and associated piping and auxiliaries. The 10 MWe modular application OTEC power system is sized in accordance with terms of the DOE contract. Heat exchangers for the 10 MWe power system exactly model those of 50 MWe power system modules because the tube banks or modules are thermodynamically and structurally equivalent to those of the 1arger plant. The turbine and generator for the 10 MWe system are one-half size, double speed versions of 40 MWe units. A modest extrapolation from that size leads to units for 50 MWe power system modules. SYSTEM DESIGN The OTEC power cycle schematic arrangement shown in Figure 1 has been basic to the study of system configurations since early in the conceptual design phase, with the exception of choice of control valves. The valve arrangement shown was selected for the preliminary design after detailed study of system control dynamics as discussed later in this paper. The evaporator tube bundles, moisture separators and liquid storage are all integrally contained in the evaporator shell; and the condenser tube bundles and hotwell storage are contained in the condenser shell as discussed later.