Back-pressure Steam Turbine Research Articles

C205 背圧蒸気タービンとチェンサイクルを組合せた熱サイクルについての研究

C205 背圧蒸気タービンとチェンサイクルを組合せた熱サイクルについての研究

The Taweelah A2 independent water and power project

Taweelah A2 is the first independent water and power project in Abu Dhabi under the government privatization policy. In response to the Abu Dhabi Water and Electricity Authority (ADWEA) request for proposals, CMS Energy prepared and submitted their offer in April 1998. Following clarifications, the Power and Water Purchase Agreement was signed on 3 October 1998. CMS appointed Mott MacDonald as their technical advisers for the tender and project phases. The Taweelah A2 plant will comprise a 720 MW combined cycle power plant and 50 migd MSF desalination plant. Three Siemens type V94.3a gas turbine generators with exhaust heat recovery boilers will supply steam to two back pressure steam turbine generators. Exhaust steam will be taken to four Hanjung 12.5 migd single deck cross tube MSF distillers, equal in capacity to the largest units ever built. Carbon dioxide gas recovered from the distiller air ejectors will be used for remineralizing the distillate. Seawater will be drawn from an existing intake channel serving the complete complex. The boilers are designed for a high level of supplementary firing to meet the wide variations in electrical load on the Abu Dhabi grid, with full water output. Construction of the US $750 million project, located between the existing Taweelah A1 and B stations, began in April 1999. First power production is scheduled in May 2000, first water production in May 2001 and completion in August 2001. The plant will be owned and operated by Emirates CMS Power, jointly owned by CMS and ADWEA. This paper describes the desalination and power plant and outlines the power and water purchase aspects of the project. The high thermal efficiency of the combined cycle and MSF plant minimizes fuel consumption, heat rejection and atmospheric emissions, making this one of the best plants in the region from an environmental standpoint.

A Coal-Fueled Combustion Turbine Cogeneration System With Topping Combustion

Cogeneration systems fired with coal or other solid fuels and containing conventional extracting-condensing or back pressure steam turbines can be found throughout the world. A potentially more economical plant of higher output per unit thermal energy is presented that employs a pressurized fluidized bed (PFB) and coal carbonizer. The carbonizer produces a char that is fed to the PFB and a low heating value fuel gas that is utilized in a topping combustion system. The topping combustor provides the means for achieving state-of-the-art turbine inlet temperatures and is the main contributor to enhancing the plant performance. An alternative to this fully coal-fired system is the partially coal, partially natural gas-fired air heater topping combustion cycle. In this cycle compressed air is preheated in an atmospheric pressure coal-fired boiler and its temperature raised further by burning natural gas in a topping gas turbine combustor. The coal fired boiler also generates steam for use in a cogeneration combined cycle. The conceptual design of the combustion turbine is presented with special emphasis on the low-emissions multiannular swirl burner topping combustion system and its special requirements and features.

Thermal power rational management using backpressure steam turbines

The paper shows the advantages of using backpressure steam turbines to cogenerate thermal power as steam and electric power in thermal electric power plants. The Romanian industry achievements within the backpressure steam turbines field are also mentioned.

Criteria for integration of combined cycle cogeneration systems in the process industries

Cogeneration systems often provide a very effective means of integrating power generation with the provision of thermal energy to an industrial process. Various types of power generating machines can be used, but combined cycle cogeneration systems can offer significant advantages over other technologies in many medium and large scale applications. The systems that are used consist of fired prime movers (usually gas turbines), discharging their exhaust heat into heat recovery steam generators. The steam raised in this way is passed through back-pressure steam turbines to extract additional power before finally delivering its residual heat content to process heating duties. This paper presents an overview of the economic trade-offs in the design of single cycle and combined cycle systems. Generalizations are derived from this investigation, leading to the identification of three distinct classes of problem for which different types of cogeneration systems (combined cycle or single cycle) are appropriate. Case study results are presented to illustrate the principles employed.

Computer program for determining optimal running conditions of a steam turbine cogeneration system

Cogeneration is an efficient way of using energy and at a national level permits an important saving in primary energy. Different systems include those with a back-pressure steam turbine and those with a pass-out condensing steam turbine. This paper deals with the basis and structure of a software pack that enables the user to determine the optimal running conditions in either case. The program is interactive, written in FORTRAN 77 and composed of six program blocks. Each block is responsible for one basic aspect of the analysis process. Because the objective function is non-linear and only point values are available, instead of algebraic expressions, the complex optimization algorithm is used. The object of the function is to minimize the hourly fuel and electricity costs during operation. Finally, the program has been applied to a cogeneration installation with a 970 kW back-pressure turbine. The results indicate that the system sometimes produces more steam per hour than required, the excess being due to the fact that the profit from the sale of electricity is greater than the cost of steam production.

Desalination and water reuse comparison of MSF and RO in dual purpose power and water plants

Recent studies of MSF and RO desalination combined with power generation have shown that selection of the desalination process is strongly influenced by both the choice of power plant cycle and the fuel cost. This Paper examines the economics of MSF coupled to gas turbine or back pressure steam turbine power plant and compares the costs with those of sea-water RO, for typical operating conditions. Energy consumption and power production from dual purpose MSF plant are compared with the power consumption of RO plant fitted with energy recovery turbines. A method for determining the cost of power and water production is presented, taking account of interaction between the systems and the effects of the power generating cycle efficiency, fuel costs and load factors. The Paper also discusses the concept of hybrid plants in which the power produced by dual purpose MSF plant can be partly used to support a reverse osmosis plant.

The triple cycle for electricity/steam supply for industry

The idea of the triple cycle is that, for those industries that require both electricity and steam (paper, textiles, tyres etc.,) electrical energy could be generated from a gas turbine. The heat of the gas turbine flue gases could be used for medium pressure steam generation. The medium pressure steam could be expanded through a back pressure steam turbine to produce more electrical energy and low pressure steam, suitable for industrial processes. In case that the amount of the low pressure steam is more than that required for the industry then the balance could be utilized again for electricity generation by using it as a heat source in a Rankine cycle. Exhausted vapour from the Rankine cycle turbine could be cooled by the make-up water necessary for the waste heat boiler. As there is no condenser and consequently, no heat rejection, except that amount of heat that will be transferred to the atmosphere by radiation and that which will remain in the flue gases after passing through the waste heat boiler, the efficiency of the triple cycle could reach 75–80%.

Conceptual design and economical evaluation of a combined MSF-RO seawater desalination plant

A combined RO-MSF-desalination plant forms together either with a back pressure steam turbine power station, or with a combined cycle power station a dual purpose plant. Its technical and economical features are discussed. Such a plant offers compared to reference concepts minimum water production costs in a 2 to 4 US $/GJ fuel cost range for the steam turbine concept and over the whole fuel cost range for the combined cycle concept.

Optimal selection of major equipment in dual purpose plants

Simulation of different operational conditions with the aid of a computer program is one of the best ways of assisting decision-makers in the selection of the most economic mix of equipment for a dual purpose plant. Using this approach this paper deals with the economic comparison of plants consisting of MSF desalinators and combustion gas or back pressure steam turbines coupled to low capacity electric power generators. The comparison is performed on the basis of the data made available by the OPTDIS computer program and the results are given in terms of yearly cost of production as the sum of capital, manpower, maintenance, fuel and chemical costs.

A new look at dual purpose, water and power, plants - economy and design features

In light of rapidly rising equipment and fuel costs, recent studies have shown some important results in the economy and optimum designs for dual purpose power/desalting complexes. The desalination cycle chosen for- detailed comparisons in this study is the well known multistage flash (MSF) evaporator, which uses brine recirculation and polyphosphate scale prevention. The multi- stage flash evaporator has found wide spread application in large plants throughout the world. Single units of up to 1400 m3/hr (9.5 MGD), acid dosing, have been built and are now in operation. In general due to corrosion problems, polyphosphate plants are now preferred over the acid one. A number of schemes for the combined production of power and. water were chosen, mainly a combination of MSF Unit with each of the following power cycle: 1. 1- Automatic extraction steam turbine 2. 2- Simple gas turbine with waste heat boiler 3. 3- Back pressure steam turbine This paper presents a study of the economic aspects, thermodynamic features and optimization analysis of each of these combined power and water production plants. The optimum value of the performance ratio and its effect on reducing the cost of water in each of the above mentioned schemes would be discussed in this paper.