Helium Turbine Research Articles

Evaluation of High-Temperature Alloys for Helium Gas Turbines

Because of the high thermal and mechanical stresses in components of a helium turbine coupled directly to a high-temperature reactor and the stringent nuclear safety requirements, an extensive materials development program has been undertaken. The candidate alloys for turbine blades and hot ducts (nickel- and molybdenum-base alloys) and for rotors (1% CrMoV and 12% chromium steels) have been tested under the expected service conditions.The results of creep/rupture, fatigue, and fracture mechanics tests on turbine blade and rotor materials are presented. The gas/metal reactions that occur in the simulated reactor coolant gas and the decontamination behavior of components are also discussed. In addition the development of a molybdenum-base alloy for turbine blading is reported.

The Relationship of Power and Heat Production with Closed Cycle Gas Turbines

As is well known, a part of the waste heat of closed cycle gas turbines can be used without any reduction in power production. However, if the plant is designed for optimal power conversion, the outlet temperatures of the repeatedly intercooled compressors are so low, that only a small part of the removed heat is useful. The closed cycle gas turbine compressor behaves analogous to a heat pump, and therefore an increase of useful heat can be realized without an undue reduction in power production. A moderate increase of the cycle pressure ratio above its optimum, a temperature increase at the compressor inlet and a reduction of the number of intercoolers are good methods for this. Measures, however, which bypass heat from the heater to the precooler, such as recuperator bypass, are not of interest. As far as closed gas turbines are considered, a further degree of freedom is given by the possibility of cycle gas inventory control, as demonstrated in combined power and heat production characteristics. These explanations are not only relevant for fossil fired plants, but also for nuclear high temperature reactors with helium turbines proposed in future.

Conceptual Design of an 80,000-shp Fossil-Fired Closed-Cycle Helium Turbine Propulsion System for Naval Ship Applications

A conceptual design was made of an 80,000-shp fossil-fired closed-cycle helium turbine system for naval propulsion applications. Various oil-fired heater and power conversion system configurations were investigated, and a reference system was selected based on a trade-off between the system performance and the component size and weight characteristics which would yield the maximum pay load capability for the ship type considered. The conceptual design of major components was made based on the parametric design results identified from a comprehensive computer program incorporating extensive past design experiences. The conceptual design drawing for the propulsion engine is presented, and a preliminary propulsion system layout applicable to a conceptual high-speed destroyer is shown. The analysis indicates that no severe integration problem is anticipated for this type propulsion engine for lightweight ship propulsion applications.

Forty years of experience on closed-cycle gas turbines

In this paper the 40 years of experience on closed-cycle gas turbines (CCGT) is emphasized to substantiate the claim that this prime-mover technology is well established. European fossil-fired plants with air as the working fluid have been individually operated over 100,000 hours, have demonstrated very high availability and reliability, and have made money for their operator owners. Following the initial success of the small air closed cycle gas turbine plants, the next step was the exploitation of helium as the working fluid for plants above 50 MWe. The first fossil fired combined power and heat plant at Oberhausen, using a helium turbine, plays an important role for future nuclear systems and this is briefly discussed. The combining of a modern reactor (HTGR) and an advanced proven power conversion system (CCGT) represents the most interesting and challenging project to engineers in the closed cycle gas turbine field. The benefits of the nuclear gas turbine power plant are such that the worldwide efforts to bring it into use should increase rapidly since the role it can play in meeting energy goals is significant. The key to acceptance of the CCGT in the near term is the introduction of a small nuclear cogeneration plant (100–300 MWe) that utilizes the waste heat, and thus demonstrates a very high fuel utilization efficiency; aspects of such a plant are outlined in this paper.

Binary cycles for a high temperature gas cooled reactor with helium turbine

The heat rejection of power plants to the environment can be reduced by using a binary (bottoming) power cycle which receives its energy input from the primary cycle cooler. High temperature gas cooled reactors with helium turbines are particularly favourable for binary cycle application due to their relatively high heat rejection temperatures and wide temperature range. The feasibility of such cycles was investigated for several working fluids. Their thermodynamic characteristics and estimated efficiency were compared. The results indicate that overall plant efficiencies of 49 per cent are attainable with hydrocarbons and 47 per cent with fluorocarbons (Freons) as working media. The incremental specific costs of the binary system would be substantially less than the cost of current nuclear plants.

Highlights and Future Development of Closed-Cycle Gas Turbines

At the moment the closed-cycle gas turbine attracts considerable attention due to: 1 The possibility of directly coupling the closed-cycle gas turbine with a gas-cooled high temperature reactor; 2 the economical use of dry coolers to reduce the thermal charge of the environment; and 3 the reduction of pollution and energy consumption, by replacing the domestic hearth by a central heating and power station. The experience gained in the development, design, construction and operation of the closed-cycle gas turbines at present in service is to be used for these new applications. In this paper, four closed-cycle gas turbine plants in operation in Europe are described and the experience obtained is summarized. The incorporation of the experience gained with these plants in the design and construction of future closed-cycle gas turbines using helium as a working medium is shown with the example of a 50 MW helium turbine. The combined application of experience and a new design philosophy results in a rather unconventional gas turbine.

Comparison of Nuclear Power Plants With Closed-Cycle Helium Turbine and With Steam Turbine Cycle for Combined Power and Steam Generation

The heat of a helium-cooled reactor can be used for combined power and steam generation either in a closed-cycle helium turbine system, the so-called single-cycle system, or in a two-cycle system which consists of a helium cycle and a secondary steam turbine cycle. The optimum data for the two systems are determined within the same range of general parameters—electric power output and quantity and quality of the steam produced—as functions of the special parameters of each particular cycle system. A method of comparing different power plant systems is shown. With this method it is possible to determine those ranges in which the efficiencies achieved with one system are higher than those obtained with the other. It is described in which way the dividing line between such ranges depends on the special parameters of the cycles. The comparison shows that the single-cycle system offers advantages.

Nuclear Power Plants With Closed-Cycle Helium Turbine for Industrial Energy Supply

All the possible arrangements of closed-cycle helium turbines for combined power and steam generation can be reduced to three variations of one single arrangement. A method for the optimum layout of this arrangement is described. Optimum data are determined for the expansion ratio and the regenerative heat exchange as functions of general parameters—electric power output and quantity and quality of the steam produced—and as functions of special parameters of the gas turbine cycle—number of intercoolers, cooling and feedwater temperatures, turbine inlet temperature and pressure drop—to obtain the best possible efficiencies.

Closure to “Discussions of ‘Nuclear Power Plants With Closed-Cycle Helium Turbine for Industrial Energy Supply’” (1971, ASME J. Eng. Power, 93, p. 162)

Closure to “Discussions of ‘Nuclear Power Plants With Closed-Cycle Helium Turbine for Industrial Energy Supply’” (1971, ASME J. Eng. Power, 93, p. 162)