Digital Computer Programmes for Steam Cycle Analysis

This paper presents a coupled heat transfer model for coal-fired boilers that integrates boiler’s fire side computational fluid dynamics (CFD) solution with the boiler’s steam cycle, and thus, can predict the boiler steam temperatures subject to different boiler design and operation conditions. In this coupled model, the heat transfer submodels describing the gas-steam heat exchange for each part of boiler heating surfaces are integrated by exchanging the steam temperatures iteratively. This coupled heat transfer model is self-consistent since it ensures the fire side heat transfer solution to always coincide with the steam temperature changes across each boiler heating surface. This model is specifically designed to provide efficient computational solutions to engineering boiler problems in which the changes of boiler steam temperatures subject to different boiler design and operation conditions are of the major concerns. This model is applied to a 320 MW subcritical boiler to evaluate the impacts of coal switching and boiler operation adjustment on boiler’s heat transfer distributions and steam temperatures. The simulation results demonstrate that this model can effectively capture the complex coupled heat transfer behavior between the fire and steam sides of boiler and serve as an efficient predictive tool for engineering boiler problems.

The author in expressing his opinion about the development of nuclear power says that the basic reason for anti-nuclear campaigning is ignorance. He finds that the concern of man for preservation of his environment is misdirected. The development of nuclear technology has proceeded with much greater attention on the problems of safety techniques and preservation of the environment than the development of such branches of technology as metallurgy, coke chemistry, mining, chemical industry, coal power stations, modern transportation, chemicalization of agriculture, etc. Therefore, the present situation in nuclear power is relatively good from the point of view of safety and possible effects on the environment. It is difficult to explain to a non-specialist (though it is actually true) that the nuclear reactor of a nuclear power station is nothing like an atomic bomb that the power station burning coal or oil offers much greater danger and harm to the environment as well as a biological threat to people than does a nuclear station or breeder reactor of the same capacity rating. The author also sees nuclear energy as the only economically feasible method available in the next few decades as an alternative to oil. This applies to countries--developed and developing--whomore » do not have oil. What is involved is not just comfort, or preservation of quality of life, but the much more fundamental problem of economic and political independence, Mr. Sakharov concludes. (MCW)« less

CCS on Offshore Oil and Gas Installation - Design of Post-Combustion Capture System and Steam Cycle

This paper covers briefly the progress that has been made in the generation of power in industrial plants. The author points out that industries and utilities are cooperating in the generation and interchange of electric energy in order to reduce waste in many manufacturing processes. Higher steam pressures and temperatures are widely used, along with superposition of new turbines on old equipment. Only a few installations have pressures and temperatures which exceed 900 lb per sq in. and 850 F, respectively. A number of prominent industrial plants are described to indicate the application of all types of steam turbines to the three steam cycles most commonly employed. Steam-pressure-reducing and desuperheating equipment, as developed for topping units in central stations, is finding new applications in industry. Where large quantities of process steam are needed, many interesting arrangements of modern equipment can be used to reduce the cost of power generation. The trend in design of boilers is toward larger units, higher steaming rates, and more complicated automatic controls to permit utilization of several different kinds of fuel in the same furnace. This presupposes the proper treatment of boiler feedwater, the importance of which is emphasized. Operating data from two outstanding installations are included. Among smaller plants there is a tendency toward the use of a self-contained boiler; also, there has been a revival of semi-outdoor constructions. Progress is being made toward better utilization of unusual fuels, such as pulverized anthracite culm, lignite, acid sludges, and black liquor, the latter of which is obtained in the process of manufacturing kraft paper. Improvements in electrical equipment for industrial plants include metal-clad switchgear, which may be located in any available space; also, air circuit breakers for voltages up to 5000 may soon be available in order to eliminate the fire hazard from using oil. Modern insulation on wire and cable offers greater resistance to high temperatures and the effects of moisture and other harmful substances.

The Biocide By-Products in Aquatic Environments Program is composed of analytical chemistry and biological phases with freshwater and marine biological subdivisions. The objectives of the analytical studies are: to identify those chloroorganic chemical compounds that result from the addition of chlorine to fresh or saltwater; to develop methods for detecting chlorinated organics in the effluents discharged to receiving water bodies from nuclear stations; and to verify laboratory findings through analysis for chlorination by-products in water and biota samples from cooling water bodies of nuclear power stations. The objectives of the biological studies are: to investigate the immediate toxicity of specific chlorination by-products (chloroform in freshwater and bromoform in marine waters); to evaluate the chronic toxicity of chlorination by-products; to follow their pathways of action; and to analyze for bioaccumulation or biomagnification of halogenated hydrocarbons on selected aquatic or marine biota.

The application of a gas turbine generally allows to increase the number of possible configurations of cogenerated heat and electrical power systems, which became a significant substitute for classic, coal-fired power plants. They are characterized by better thermodynamical, economical, ecological and operating indexes. Gas turbine units are also the best option for the moderinization of existing power plants. This paper discusses the effectiveness of various technological configurations with gas turbines, which are to be applied during modernization projects of already existing conventional combined heat and power plants. In the analysis and entropy methods were applied. Algorithms of the entropy method allow to determine the entropy generation in each section of a combined heat and power (CHP) plant. Several criteria were taken into consideration while analyzing the effectiveness of technological cycle configurations with gas turbines. These include the energy effectiveness, the efficiency of the HRSG and the steam cycle, the efficiency of the whole thermal electric power station, the exergetic efficiency of the HRSG and the steam cycle, and the fuel efficiency index. It was assumed that gas turbines operate under their nominal conditions. The composite curves were also taken into consideration while choosing the type of the turbine. The modernization project tends not to eliminate those exiqsting power plant sections (machines and equipment), which are able to operate further. The project suggests that those units should remain in the system, which satisfy the applied durability criterion. The last phase of the optimization project focuses on the sensibility verification of several steam-gas CHP plant parameters and their influence on the whole system.

In order to improve the efficiency and power output of combined cycle gas turbine (CCGT) power plants, a new design of combined cycle with reheat gas turbine (RGT) matched with supercritical Rankine cycle is proposed. Steam cycle is composed of supercritical single pressure level once-through with reheat Heat Recover Steam Generator (SCHRSG). Aspen plus software has been used to calculate the process and to study the performances at different design conditions. The optimization of combined cycle parameters is based on maximizing combined cycle efficiency and has been done using a genetic algorithm (GA). The results are compared with those combined cycles where the gas turbine are not reheated and the HRSG has subcriticai three pressure levels with reheat (3HRSG); dramatically advantages in efficiency are highlighted.

A general superstructure for the optimal synthesis and design of power and inverse Rankine cycles

Multi-objective optimization and exergo-economic assessment of a solar-biomass multi-generation system based on externally-fired gas turbine, steam and organic Rankine cycle, absorption chiller and multi-effect desalination

Riley Stoker Corporation is leading an R&D program for the expedited development of a new generation of pulverized coal-fired boiler systems. The overall objective is to develop relatively near term technologies to produce Low-Emission coal-fired Boiler Systems (LEBS) ready for full scale commercial generating plants by the end of the decade. The specific goal is to develop a LEBS incorporating an advanced slagging system for improved ash management in addition to meeting the emission and performance goals. This Concept Selection Report documents an evaluation of subsystems and LEBS concepts. Priority was given to the evaluation of the boiler system, steam cycle, and advanced slagging combustor. Some findings are as follows: An ultra supercritical steam cycle is required to meet project efficiency goals. The cost of electricity (COE) for this cycle, at today`s fuel prices, and without externality costs, is slightly higher than a conventional subcritical cycle. The supercritical cycle includes a substantial contingency. Reduction of contingency, escalation of fuel cost, or inclusion of externalities all lead to a lower COE for the supercritical cycle compared to the subcritical cycle. The advanced cycle is selected for inclusion in the LEBS. The advanced slagging combustor (TVC), should it meet the projected performance goals, yields a lower COE than either a dry firing system or a more conventional slagger fitted with post combustion NO{sub x} controls. Verification and development of the advanced slagger performance is the primary focus of this project. A commercial slagging configuration know as U-firing is selected for parallel development and as a platform for adaptation to the TVC.

Technical polygeneration potential in palm oil mills in Colombia: A case study

This, the fourth Finniston Lecture, recalls some of the key events which culminated in the construction of the first commercial pressurised water reactor (PWR) power station in the UK. It will highlight those areas which illustrate the wide ranging contribution which Monty made in the field of materials for nuclear power plant, to steelmaking, and to excellence in engineering, and his ability to bring together scientific understanding and successful management. Safety, the Pressure boundary, Incredibility of failure, Reliability, Inspection, and Testing are some of the topics to be discussed. At the time that the Central Electricity Generating Board (CEGB) sought permission to build Sizewell B, the public was becoming increasingly sceptical about both the safety and the economics of nuclear power. By the early 1980s neither the gas cooled reactor stations in the UK nor the PWR stations in the USA were delivering on their promises of cheap electricity. Safety and operational problems were emerging, most notably in the Three Mile Island incident. While UK safety standards withstood severe scrutiny, a much higher level of proof that these standards could be met was required. The CEGB and the UK nuclear industry had to deliver a station which incorporated many new safety related features and which would achieve very much higher reliability and availability than had been so far achieved by any other nuclear station. The industry had been stung by accusations of secrecy and was determined to justify and fully account for its expenditure on Sizewell B to the public. Sizewell B achieved this objective as a result of close coordination and the enlightened approach taken by the scientific and nuclear safety community, US, French, and UK nuclear design and manufacturing industry, and the station construction, commissioning, and operating teams.

In this paper, Poly-crystalline silicon carbide (poly-sic) Micro-electromechanical systems (MEMS) capacitive pressure sensor operating in harsh environment in touch mode is proposed, The principle of the paper is to design, obtain analytical solution and compare the results with the simulation for a circular diaphragm deflection before and after touch point. The sensor demonstrated a high temperature sensing capability up to 400°C, the device achieves a linear characteristic response and consists of a circular clamped-edges poly-sic diaphragm suspended over sealed cavity on a silicon carbide substrate. The sensor is operating in touch mode capacitive pressure sensor, The advantages of a touch mode are the robust structure that make the sensor to withstand harsh environment, near linear output, and large over-range protection, operating in wide range of pressure, higher sensitivity than the near linear operation in normal mode, The material is considered to be used for harsh environment is SiC (Silicon Carbide), Because of SiC owing excellent electrical stability, mechanical robustness, and chemical inertness properties and the application of pressure sensors in harsh environments are, such as automotive industries, aerospace, oil/logging equipments, nuclear station, and power station. We are simulating MEMS capacitive pressure sensor to optimize the design, improve the performance and reduce the time of fabricating process of the device. The proposed touch mode MEMS capacitive pressure sensor demonstrated diaphragm ranging from 150 μm to 360 μm in diameter, with the gap depth from 0.5 μm to 7.5 μm and the sensor exhibit a linear response with pressure from 0.05 Mpa to 10 Mpa.

Since in the use of coal the direct recourse to combined cycles is impractical, binary alkali metal steam cycles are recognized as an interesting and feasible option. Past attempts to employ metal vapour conversion cycles for power generation are surveyed. After selecting potassium and cesium as possible candidate fluids, the binary cycle is optimized taking as variables the top temperature, the number of condensation levels of the metal vapour cycle, and the characteristics of the bottoming steam cycle. At vaporization temperatures in the range of 750—850 °C, metal vapour cycle efficiencies of about 20—24 per cent and binary cycle efficiencies of 57—61 per cent seem achievable. A survey of available building materials in the steel and in the super-alloy class showed that top temperatures of 800–850 °C could be reached with state-of-the-art alloys. Metal vapour turbines are recognized as a key issue of binary plant design in that exhaust volume flows are very large even for a moderate turbine capacity. For a double flow solution, limiting turbine dimensions to those of existing 1500 r/min steam low pressure stages leads to metal vapour turbine capacity of 120 MW for potassium and 170 MW for cesium. Assuming that in the future, better materials will be available allowing alkali metal vaporization temperatures in the range of 1400–1500 °C, a ternary solution is proposed which employs lithium, potassium, and steam as working fluids. At 1450 °C top temperature, a cycle efficiency in excess of 70 per cent is attained.

Combining waste-to-energy steam cycle with gas turbine units