Simulating Pressure Transient Events in the Fuel Gas Supply to a Multi-Block Combined Cycle Plant

Author(s):  
Robert Schroeder ◽  
Matthew Zitkus ◽  
Michael Czyszczewski ◽  
Beniamino Rovagnati

As power plant combustion turbines (CTs) are pushed towards higher thermal efficiencies, increased attention is being given to operating requirements for their fuel gas supply such as the maximum allowable rate-of-change in pressure. It is important to perform detailed analyses for multi-unit plants to ascertain whether pressure transient events, such as those caused by initial trip of one or two combustion turbines, will cause additional combustion turbines to trip off. In this paper, single and dual CT trips were postulated in a near-realistic combined cycle power plant. Predictions of the gas flow behavior, along with propagation and superposition of pressure waves, was carried out using the method of characteristics (MOC) for compressible flows. Specifically, the rate of change in fuel gas supply pressure to each CT was monitored and compared against a typical manufacturer limit of 0.8 bar/s. Instances where simulations showed this threshold exceeded were noted, since such events correspond to automatic valve closure that would shut down one more CT and thereby further reduce plant electrical output. The overall goal of fuel gas transient analyses is to improve pipeline designs, iteratively when necessary, such that those additional trips are avoided. To that end, this paper presents several simulation cases to illustrate pressure transient phenomena and to show the impact of various pipeline design alterations, some of which caused 40% reductions in the worst pressure rate-of-change during simulations.

2020 ◽  
Vol 6 ◽  
pp. 929-933
Author(s):  
Teerawat Thepmanee ◽  
Chakri Nachasingha ◽  
Sart Kummool

2022 ◽  
Vol 8 ◽  
pp. 684-690
Author(s):  
Teerawat Thepmanee ◽  
Amphawan Julsereewong ◽  
Sawai Pongswatd

2021 ◽  
Author(s):  
Pugalenthi Nanadagopal ◽  
Animesh Pandey ◽  
Manjunath More ◽  
Pertik Kamboj

Abstract In Gas turbine-based combined cycle power plant market, the customer conducts an economic evaluation of competitive products to decide their buying option. There are different methods to calculate the economics of a power plant like Levelized cost of electricity (LCOE), Net present value (NPV) and payback period. LCOE methodology is commonly used for lifecycle cost analyses for combine cycle power plant that covers cost details of the plant and plant performance over the complete lifetime of a power plant from construction to retiring. Typically, it includes a combine cycle power plant ownership costs (Total plant cost and operating & maintenance cost) and combine cycle power output and efficiency. This LCOE method is helpful to compare power generation system that use similar technologies. This paper encompasses the LCOE calculation method, assumptions & approach to analyze the impact of key parameters of the electrical generation cost. They key parameters includes combine cycle output, combine cycle efficiency, fuel cost, annual operating hours, capital charge factor, annual operating hours, power plant life, discount rate, nominal escalation rate, operating & maintenance cost. This paper analyses result will provide insights to the customer & Gas turbine-based OEM (Own Equipment Manufacturing) companies to focus on different area/parameters to reduce the unit cost of generating electricity.


Author(s):  
Thormod Andersen ◽  
Hanne M. Kvamsdal ◽  
Olav Bolland

A concept for capturing and sequestering CO2 from a natural gas fired combined cycle power plant is presented. The present approach is to decarbonise the fuel prior to combustion by reforming natural gas, producing a hydrogen-rich fuel. The reforming process consists of an air-blown pressurised auto-thermal reformer that produces a gas containing H2, CO and a small fraction of CH4 as combustible components. The gas is then led through a water gas shift reactor, where the equilibrium of CO and H2O is shifted towards CO2 and H2. The CO2 is then captured from the resulting gas by chemical absorption. The gas turbine of this system is then fed with a fuel gas containing approximately 50% H2. In order to achieve acceptable level of fuel-to-electricity conversion efficiency, this kind of process is attractive because of the possibility of process integration between the combined cycle and the reforming process. A comparison is made between a “standard” combined cycle and the current process with CO2-removal. This study also comprise an investigation of using a lower pressure level in the reforming section than in the gas turbine combustor and the impact of reduced steam/carbon ratio in the main reformer. The impact on gas turbine operation because of massive air bleed and the use of a hydrogen rich fuel is discussed.


Author(s):  
Weimar Mantilla ◽  
José García ◽  
Rafael Guédez ◽  
Alessandro Sorce

Abstract Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study. To establish the hourly dispatch of the power plant and the operation mode of the inlet conditioning unit to either cool down or heat up the gas turbine inlet air, a mixed-integer linear optimization (MILP) was formulated using MATLAB, aiming to maximize the operational profit of the plant within a 24-hours horizon. To assess the impact of the proposed unit operating under this dispatch strategy, historical data of electricity and natural gas prices, as well as meteorological data and CO2 emission allowances price, have been used to perform annual simulations of a reference power plant located in Turin, Italy. Furthermore, different equipment capacities and parameters have been investigated to identify trends of the power plant performance. Lastly, a sensitivity analysis on market conditions to test the control strategy response was also considered. Results indicate that the inlet conditioning unit, together with the dispatch optimization, increases the power plant’s operational profit by achieving a wider operational range, particularly important during peak and off-peak periods. For the specific case study, it is estimated that the net present value of the CCGT integrated with the ICU is 0.5% higher than the power plant without the unit. In terms of technical performance, results show that the unit reduces the minimum environmental load by approximately 1.34% and can increase the net power output by 0.17% annually.


Author(s):  
M. Gambini ◽  
M. Vellini

In this paper the overall performance of a new advanced mixed cycle (AMC), fed by hydrogen-rich fuel gas, has been evaluated. Obviously, hydrogen must be produced and here we have chosen the coal gasification for its production, quantifying all the thermal and electric requirements. At first, a simple combination between hydrogen production section and power section is performed. In fact, the heat loads of the first section can be satisfied by using the various raw syngas cooling, without using some material streams taken from the power section, but also without using part of heat, available in the production section and rejected into the environment, in the power section. The final result is very poor: over 34%. Then, by using the Pinch Technology, a more efficient, even if more complex, solution can be conceived: in this case the overall efficiency is very interesting: 39%. These results are very similar to those of a combined cycle power plant, equipped with the same systems and analyzed under the same hypotheses. The final result is very important because the “clean” use of coal in new power plant types must be properly investigated: in fact coal is the most abundant and the cheapest fossil fuel available on earth; moreover, hydrogen production, by using coal, is an interesting outlook because hydrogen has the potential to become the main energy carrier in a future sustainable energy economy.


1999 ◽  
Vol 122 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Richard A. Newby ◽  
Wen-Ching Yang ◽  
Ronald L. Bannister

Fuel gas cleanup processing significantly influences overall performance and cost of IGCC power generation. The raw fuel gas properties (heating value, sulfur content, alkali content, ammonia content, “tar” content, particulate content) and the fuel gas cleanup requirements (environmental and turbine protection) are key process parameters. Several IGCC power plant configurations and fuel gas cleanup technologies are being demonstrated or are under development. In this evaluation, air-blown, fluidized-bed gasification combined-cycle power plant thermal performance is estimated as a function of fuel type (coal and biomass fuels), extent of sulfur removal required, and the sulfur removal technique. Desulfurization in the fluid bed gasifier is combined with external hot fuel gas desulfurization, or, alternatively with conventional cold fuel gas desulfurization. The power plant simulations are built around the Siemens Westinghouse 501F combustion turbine in this evaluation. [S0742-4795(00)00502-0]


Author(s):  
W. C. Yang ◽  
R. A. Newby ◽  
R. L. Bannister

Air-blown coal gasification for combined-cycle power generation is a technology soon to be demonstrated. A process evaluation of air-blown IGCC performed to estimate the plant heat rate, electrical output and potential emissions are described in this paper. A process model of an air-blown IGCC power system based on the Westinghouse 501F combustion turbine was developed to conduct the performance evaluation. Parametric studies were performed to develop an understanding of the power plant sensitivity to the major operating parameters and process options. Advanced hot fuel gas cleaning and conventional cold fuel gas cleaning options were both considered.


Author(s):  
John S. Brushwood ◽  
Ken Campbell ◽  
C. V. Hanson ◽  
Andras Horvath ◽  
Thomas Vivenzio

The Minnesota Valley Alfalfa Producers (MnVAP), a farmer owned cooperative, is developing a 75 MW combined cycle power plant integrated with alfalfa processiag facilities in southwestern Minnesota. The Minnesota Agri-Power (MAP) project is supported by the U. S. Department of Energy and a project development team that includes Stone & Webster, the University of Minnesota, United Power Association, Carbona Corporation/Kvaerner Pulping Inc. and Westinghouse. Alfalfa processing facilities separate the fibrous stem material from the protein-rich leaf fraction. The resulting alfalfa leaf meal (ALM) is further processed into a variety of valuable livestock feed products. Alfalfa stem material is gasified using air-blown fluidized bed technology to produce a hot, clean, fuel gas. The fuel gas is fired in a combustion turbine and the exhaust heat is used to produce steam to power a steam turbine. At base load, the electric power plant will consume 1000 tons per day of biomass fuel. This paper briefly describes the project development activities of the alfalfa feed trials and the combined cycle power plant. This commercial scale demonstration represents an important milestone on a continuing pathway towards environmentally and economically sustainable energy systems.


Author(s):  
P. Pillai ◽  
C. Meher-Homji ◽  
F. Meher-Homji

High thermal efficiency of LNG liquefaction plants is of importance in order to minimize feed usage and to reduce CO2 emissions. The need for high efficiency becomes important in gas constrained situations where savings in fuel auto consumption of the plant for liquefaction chilling and power generation can be converted into LNG production and also from the standpoint of CO2 reduction. This paper will provide a comprehensive overview of waste heat recovery approaches in LNG Liquefaction facilities as a measure to boost thermal efficiency and reduce fuel auto-consumption. The paper will cover types of heating media, the need and use of heat for process applications, the use of hot oil, steam and water for process applications and direct recovery of waste heat. Cogeneration and combined cycle approaches for LNG liquefaction will also be presented along with thermal designs. Parametric studies and cycle studies relating to waste heat recovery from gas turbines used in LNG liquefaction plants will be provided. The economic viability of waste heat recovery and the extent to which heat integration is deployed will depend on the magnitude of the accrual of operating cost savings, and their ability to counteract the initial capital outlay. Savings can be in the form of reduced fuel gas costs and reduced carbon dioxide taxes. Ultimately the impact of these savings will depend on the owner’s measurement of the value of fuel gas; whether fuel usage is accounted for as lost feed or lost product. The negative impacts include the reduction in nitrogen rejection that occurs with reduced fuel gas usage and the power restrictions imposed on gas turbine drivers due to the increased exhaust system back-pressure caused by the presence of the WHRU. When steam systems are acceptable, a cogeneration type liquefaction facility can be attractive. In addition to steam generation and hot oil heating, newer concepts such as the use of ORCs or supercritical CO2 cycles will also be addressed.


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