LMFBR Steam Generator Materials Development at Westinghouse

The impact of Materials and Processes (M and P) development activities at the Nuclear Components Division - Breeder Reactor Components Project of Westinghouse are described. Nine specific M and P programs have been performed over the past five years and the conclusions drawn from each are summarized herein. These engineering activities could be classified as component design, fabrication, and testing results. However, the discussion presented is from a materials engineer’s viewpoint as to how the previously proposed development tasks have answered existing questions about either design, manufacturing, or plant operation. The nine areas which are discussed include (i) double-wall tubing, (ii) tube-to-tubesheet welding, (iii) few tube model fabrication and testing, (iv) tube support plates, (v) shell welding, (vi) convoluted shell expansion joint, (vii) water chemistry and corrosion behavior, (viii) chemical cleaning, and (ix) surface contamination protection.

Steam-Cooled Gas Turbine Casings, Struts, and Disks in a Reheat Gas Turbine Combined Cycle: Part I—Compressor and Combustor

High-cycle pressure-ratio (38–42) gas turbines being developed for future aircraft and, in turn, industrial applications impose more critical disk and casing cooling and thermal-expansion problems. Additional attention, therefore, is being focused on cooling and the proper selection of materials. Associated blade-tip clearance control of the high-pressure compressor and high-temperature turbine is critical for high performance. This paper relates to the use of extracted steam from a steam turbine as a coolant in a combined cycle to enhance material selection and to control expansion in such a manner that the cooling process increases combined-cycle efficiency, gas turbine output, and steam turbine output.

Conversion of a Heavy-Duty Industrial Gas Turbine to Combined Cycle

This paper discusses the evaluation, design, and operation of a combined-cycle plant for Bahamas Electricity Corporation in Nassau, Bahamas. The plant was designed to provide maximum fuel efficiency, satisfactorily operate to 40 percent load, and includes provisions for heavy oil firing in the gas turbine. The system was started up July, 1982 and has been in successful operation since then.

Gas Turbine Compressor Interstage Cooling Using Methanol

An earlier study demonstrated the theoretical potential of the concept of injecting methanol into a gas turbine compressor inlet as a means of increasing cycle thermal efficiency. To attain the full potential of such a system, continuous shifting vapour/liquid equilibrium is required which would pose formidable difficulties in practice due to the presence of liquid in the compressor blading. This study evaluates a more practicable configuration in which the alcohol is injected between stages of a multistage machine so that, due to the higher air temperatures, evaporation is complete before the mixture enters subsequent stages. Through a computer analysis, it is shown that this arrangement would retain most of the potential of the concept while greatly reducing the design and operating problems.

Erosion Pattern of Twisted Blades by Particle Laden Flows

This paper presents the results of a study to predict turbomachine blade erosion by particle laden flows. Using statistical methods, this work combines particle trajectory calculations with experimental erosion data to determine the erosion of blades. The results of the calculations are presented to show the different patterns of blade material removal distribution over the surface of twisted stator blades for different particle sizes.

The Effect of Flat Bar Supports on the Crossflow Induced Response of Heat Exchanger U-Tubes

A wind tunnel study was conducted to determine the effect of flat bar supports on the crossflow induced response of heat exchanger U-tubes. The 13-mm-dia tubes formed a triangular array with a pitch ratio of 1.57 and a mean U-bend diameter of about 1.5 m. A 0.3-m-long section of the array was exposed to a flow parallel to the plane of the U-bends. Experiments were conducted with no supports, with one set of flat bars at the apex, and with two sets of flat bar supports at the apex and 45 deg points. In each case, the tube response was monitored to a flow velocity beyond that required for fluid elastic instability. Limited experiments were also conducted to examine the effect of tube support clearance on tube response. Conclusions are drawn regarding the effectiveness of flat bars as U-bend antivibration supports.

An Advanced Radial-Component Industrial Turbine Engine

The first engine of a new family of high performance, industrial radial turbines is presented. The new single-shaft, 1500-kW site rated KG3 is built upon extensive experience from the field proven KG2 of the same nominal power. The KG3 is being developed both as a simple cycle and recuperated engine providing specific fuel consumptions in the range of 0.29–0.19 kg/kW-hr (0.47–0.32 lbs/hp-hr). This engine makes use of a high specific speed, high pressure ratio centrifugal compressor combined with a very high tip speed uncooled radial turbine to obtain optimized aerodynamic matching. Several novel design features are described.

Development of the Transpiration Air-Cooled Turbine for High-Temperature Dirty Gas Streams

Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.

Experimental Investigation on Denting in PWR Steam Generators: Causes and Corrective Actions

Denting studies have been undertaken in order to assess the influence of the most important parameters which could initiate corrosion of the carbon steel occurring in the tube-tube support plate crevices of some PWR steam generators. Tests have been carried out in model boilers where feedwater was polluted with sea or river water. Specific effects of chloride or sulfate and influence of oxygen content, magnetite addition and pH value were investigated. In magnetite prepacked crevices, denting is obtained within 1000 hrs for seawater pollution of 0.3 ppm chloride at the blowdown. In neutral chloride or in river water, denting is observed only with oxygen addition. Denting prevention is effective in the case of an on-line addition of phosphate, boric acid, or calcium hydroxide. For denting stopping, boric acid or calcium hydroxide is efficient even with a high seawater pollution. Soaks cannot stop denting if they are not followed by an on-line treatment (boric acid, calcium hydroxide). With quadrifoil holes, denting doesn’t occur. In very severe test conditions, 13 percent Cr steel can be corroded, but the corrosion rate is low and oxide morphology is different from that growing on carbon steel.

On the Transient Interaction of Centrifugal Compressors and Their Piping Systems

The problems of surge and other low-frequency pulsation phenomena in centrifugal compressors are described in terms of both machine (head curve) characteristics and the flow impedance characteristics of its attached piping. Flow stability criteria are presented in terms of net modal damping, as the combination of piping acoustic damping and equivalent negative damping of the compressor in the surge region of its performance curve. Surge and instability frequencies are related to acoustic reactance of the piping system. Finally, theoretical concepts are verified both by electrical analog models and by field and laboratory data on real compressors. This paper provides some new and significant findings on the dynamic interaction of centrifugal compressors with piping systems and describes the basic phenomena underlying these interactions. Good agreement is shown between predicted and measured surge frequencies, and for those termed “piping resonance surge” produced by high flow offsets or flat spots in the head curve.