ABSTRACT

The details of' the power plant considered include the heat transfer system utilizing falling film direct contact evaporation and condensation, design of the large steam turbine and flow passages, water pumping systems and overall plant layout including the supporting platform. Cost estimates are made for a complete system having a 100 MW net power output.

INTRODUCTION

The basic idea of the open cycle thermal difference sea power plant was introduced by D?Arsonval in 1881, and in 1928 Claude actually built an operating system and proved its feasibility; however, the technology at that period of time was not sufficiently advanced and the cost of coal and oil was low, so that no economic benefit would be realized from the further development of such systems. That is, the capital costs of the construction, maintenance and power transmission of the system were so high that they far outweighted the savings accrued by not having to supply fuel. At the present, however, with fuel prices soaring, there is justifiably renewed interest in the sea based power plants. Claude's open cycle system uses the sea surface water as its heat source, the cool deep sea water for heat rejection, and the sea water vapor itself as the working medium. Because of the very low density of the water vapor at available temperatures, the steam turbine and steam passages become extremely large by usual standards and the entire system must be maintained at a soft vacuum. To avoid these consequences of the open cycle system Boucherot, a colleague and constructive critic of Claude, proposed a closed cycle using as working medium a fluid such as ammonia which would have a substantial gas density at the available sea surface temperatures. In this way, the size of the power turbine and gas passages would be reduced and the entire system would operate at pressures above atmospheric. There are, nevertheless, important differences in the heat exchange systems of the boiler and condenser. In the open cycle system, it is possible to utilize direct contact heat transfer which is highly efficient and does not utilize expensive metal heat transfer surfaces. The closed cycle system requires a substantially larger heat transfer surface and materials with good conductivity, high corrosion resistance, and excellent anti-fouling characteristics, i.e., expensive. Each system therefore has its expensive parts and in the final analysis the total cost of the system determines the cost of the power generated. Recent studies have devoted major emphasis to the closed cycle system without conclusive evidence that it is indeed the least-cost system. In the present report an analysis is made of the open cycle system, in which the heat-transfer-system is sized, the vapor turbine is designed, and a complete layout including the supporting platform is-presented. From the design developed some preliminary cost estimates are obtained.

GENERAL CONSIDERATIONS OF OPEN AND CLOSED CYCLE SYSTEMS

The thermodynamic efficiency of the solar sea power plants is governed by the temperature differences available, the energy losses associated with pumping of huge quantities of sea water, and the inherent losses of real machinery.

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