Performance Testing of Combined Cycle Power Plant in Phased Construction

Author(s):  
Hugh Jin ◽  
Terrence B. Sullivan ◽  
Jeffrey R. Friedman

Gas turbines in combined cycle (CC) power plants, in phased construction situations, usually operate for several months in the simple cycle (SC) mode while the steam portion of the plant is being constructed. At the time of commissioning the combined cycle phase, the gas turbines typically have accumulated a considerable number of operating hours and have possibly experienced some degradation, especially on turbines that have run on dual fuels. To determine the combined cycle new and clean performance, it is necessary to employ a phased testing approach. The phased testing approach involves testing the gas turbines when they are in new and clean condition and combining those results with the measured new and clean steam turbine cycle performance. The method of the phased testing has been introduced in ASME PTC 46 (1996) “Performance Test Code on Overall Plant Performance”. This paper will discuss in detail the test protocol, fundamental equations, corrections, and uncertainty analysis of phased testing. This paper will also discuss performance degradation and engine setting changes between the phases.

Author(s):  
Shane E. Powers ◽  
William C. Wood

With the renewed interest in the construction of coal-fired power plants in the United States, there has also been an increased interest in the methodology used to calculate/determine the overall performance of a coal fired power plant. This methodology is detailed in the ASME PTC 46 (1996) Code, which provides an excellent framework for determining the power output and heat rate of coal fired power plants. Unfortunately, the power industry has been slow to adopt this methodology, in part because of the lack of some details in the Code regarding the planning needed to design a performance test program for the determination of coal fired power plant performance. This paper will expand on the ASME PTC 46 (1996) Code by discussing key concepts that need to be addressed when planning an overall plant performance test of a coal fired power plant. The most difficult aspect of calculating coal fired power plant performance is integrating the calculation of boiler performance with the calculation of turbine cycle performance and other balance of plant aspects. If proper planning of the performance test is not performed, the integration of boiler and turbine data will result in a test result that does not accurately reflect the true performance of the overall plant. This planning must start very early in the development of the test program, and be implemented in all stages of the test program design. This paper will address the necessary planning of the test program, including: • Determination of Actual Plant Performance. • Selection of a Test Goal. • Development of the Basic Correction Algorithm. • Designing a Plant Model. • Development of Correction Curves. • Operation of the Power Plant during the Test. All nomenclature in this paper utilizes the ASME PTC 46 definitions for the calculation and correction of plant performance.


Author(s):  
Helmer Andersen

Fuel is by far the largest expenditure for energy production for most power plants. New tools for on-line performance monitoring have been developed for reducing fuel consumption while at the same time optimizing operational performance. This paper highlights a case study where an online performance-monitoring tool was employed to continually evaluate plant performance at the Kalaeloa Combined Cycle Power Plant. Justification for investment in performance monitoring tools is presented. Additionally the influence of various loss parameters on the cycle performance is analyzed with examples. Thus, demonstrating the potential savings achieved by identifying and correcting the losses typically occurring from deficiencies in high impact component performance.


Author(s):  
Justin Zachary ◽  
Alex Khochafian

Based on the present revival of coal as the fossil fuel of choice for power generation, there is a high probability that several IGCC projects will materialize in the near future. One of the challenges facing the Owners, EPC Contractors and OEM’s will be to define the performance commercial guarantees and the practical means to determine them. In addition following the current huge upturn in conventional supercritical coal fired power plants, a large number of facilities will conduct thermal performance tests. The proper conductance of the test, data collection and correction to reference conditions, have many technical implications and could affect drastically the commercial outcome of a project both for the Contractor and the Owner. For IGCC plants, in anticipation of this probability, ASME Performance Test Committee had developed a Performance Test Code for such type of plant — PTC 47, which was published in January 2007. In the first part, the paper will provide details about the specific challenges facing the implementation of the Code, in particular the proposed use of the input/output method (mass and energy balance). The presentation will cover other highlights of the code recommendations. The methodology is fully applicable to conventional power plants, since they use same type of fuel. The determination of the heat input based on actual continuous measurement of the mass flow and composition of the coal will be discussed in details. The practicality and the measurement uncertainty associated with fuel composition will also be analyzed. A comparison with the indirect method for determination of the heat input will also be presented. The article will evaluate how the code requirements are reflected in the definition of the power plant design, configuration and instrumentation. The implications of test tolerance as a commercial issue and measurement uncertainty as a technical issue will also be presented and evaluated Other unique aspects of the entire IGCC plant performance testing will be discussed: (1) stability criteria related to the gasification and integration processes, (2) corrections from test to guarantees conditions due to complex chemical, mechanical processes. Finally, the article will indicate the progress on the development of performance evaluation methodologies for other main IGCC components: gasifier, air separation unit, gas cleaning systems and Power Island.


Author(s):  
Michael McClintock ◽  
Kenneth L. Cramblitt

Monitoring thermal performance in the current generation of combined cycle power plants is frequently a challenge. The “lean” plant staff and organizational structure of the companies that own and operate these plants frequently does not allow the engineering resources to develop and maintain an effective program to monitor thermal performance. Additionally, in many combined cycle plants the highest priority is responding to market demands rather than maintaining peak efficiency. Finally, in many cases the plants are not designed with performance monitoring in mind, thus making it difficult to accurately measure commonly used indices of performance. This paper describes the performance monitoring program being established at a new combined cycle plant that is typical of many combined cycle plants built in the last five years. The plant is equipped with GE 7FA gas turbines and a GE reheat steam turbine. The program was implemented using a set of easy-to-use spreadsheets for the major plant components. The data for the calculation of indices of performance for the various components comes from the plant DCS system and the PI system (supplied by OSIsoft). In addition to the development of spreadsheets, testing procedures were developed to ensure consistent test results and plant personnel were trained to understand, use and maintain the spreadsheets and the information they produce.


Author(s):  
Sang Ip ◽  
Mehdi Soltani

In a gas turbine combined cycle, the performance guarantees are based on a specific set of base reference conditions. The actual plant performance is measured during a performance test, which usually occurs under conditions different from the base reference conditions. ASME Performance Test Code (PTC) 46, “Performance Test Code on Overall Plant Performance,” [1] addresses various cycle configurations and the fundamental equations used to correct results at the test condition back to base reference conditions. When the test requires duct firing of the heat recovery steam generator(s), then developing the correction curves poses unique challenges to the cycle engineer. This paper will review the issues and techniques used to develop the appropriate correction curves for the duct-fired combined cycle.


Author(s):  
Thomas P. Schmitt ◽  
Christopher R. Banares ◽  
Benjamin D. Morlang ◽  
Matthew C. Michael

Many modern power plants feature gas turbines with advanced control systems that allow a greater level of performance enhancements, over a broader range of the combined-cycle plant’s operating environment, compared to conventional systems. Control system advancements tend to outpace a plant’s construction and commissioning timescale. Often, the control algorithms and settings in place at the final guarantee performance test will differ significantly from those envisioned during the contract agreement phase. As such, the gas turbine’s actual performance response to changes in boundary conditions, such as air temperature and air humidity, will be considerably different than the response illustrated on the initial correction curves. For the sake of technical accuracy, the performance correction curves should be updated to reflect the as-built, as-left behavior of the plant. By providing the most technically accurate curves, the needs of the new plant performance test are satisfied. Also, plant operators receive an accurate means to trend performance over time. The performance correction curves are intended to provide the most technically accurate assurance that the corrected test results are independent of boundary conditions that persist during the performance test. Therefore, after the gas turbine control algorithms and/or settings have been adjusted, the performance correction curves — whether specific to gas turbines or overall combined-cycle plants — should be updated to reflect any change in turbine response. This best practice maintains the highest level of technical accuracy. Failure to employ the available advanced gas turbine control system upgrades can limit the plant performance over the ambient operating regime. Failure to make a corresponding update to the correction curves can cause additional inaccuracy in the performance test’s corrected results. This paper presents a high-level discussion of GE’s recent gas turbine control system advancements, and emphasizes the need to update performance correction curves based on their impact.


Author(s):  
W. Peter Sarnacki ◽  
Richard Kimball ◽  
Barbara Fleck

The integration of micro turbine engines into the engineering programs offered at Maine Maritime Academy (MMA) has created a dynamic, hands-on approach to learning the theoretical and operational characteristics of a turbojet engine. Maine Maritime Academy is a fully accredited college of Engineering, Science and International Business located on the coast of Maine and has over 850 undergraduate students. The majority of the students are enrolled in one of five majors offered at the college in the Engineering Department. MMA already utilizes gas turbines and steam plants as part of the core engineering training with fully operational turbines and steam plant laboratories. As background, this paper will overview the unique hands-on nature of the engineering programs offered at the institution with a focus of implementation of a micro gas turbine trainer into all engineering majors taught at the college. The training demonstrates the effectiveness of a working gas turbine to translate theory into practical applications and real world conditions found in the operation of a combustion turbine. This paper presents the efforts of developing a combined cycle power plant for training engineers in the operation and performance of such a plant. Combined cycle power plants are common in the power industry due to their high thermal efficiencies. As gas turbines/electric power plants become implemented into marine applications, it is expected that combined cycle plants will follow. Maine Maritime Academy has a focus on training engineers for the marine and stationary power industry. The trainer described in this paper is intended to prepare engineers in the design and operation of this type of plant, as well as serve as a research platform for operational and technical study in plant performance. This work describes efforts to combine these laboratory resources into an operating combined cycle plant. Specifically, we present efforts to integrate a commercially available, 65 kW gas turbine generator system with our existing steam plant. The paper reviews the design and analysis of the system to produce a 78 kW power plant that approaches 35% thermal efficiency. The functional operation of the plant as a trainer is presented as the plant is designed to operate with the same basic functionality and control as a larger commercial plant.


Author(s):  
Rattan Tawney ◽  
Cheryl Pearson ◽  
Mona Brown

Deregulation and growth in the power industry are causing dramatic changes in power production and distribution. The demand for peak power and potentially high revenues due to premium electricity rates has attracted independent developers to the concept of Merchant Power Plants (MPPs). Over 100,000 MW of greenfield capacity is currently being developed through approximately 200 merchant plants in North America. These MPPs will have no captive customers or long-term power purchase agreements, but will rely on selling electricity into a volatile electricity spot market. Because of this, MPPs need the capability to export as much power as possible on demand. MPPs must also have the capability to produce significant assets in order to compete in the marketplace, based on both technical and commercial operation factors such as value engineering, life-cycle cost management, and information technology. It is no surprise then, that almost all merchant project developers have specified combined cycle (CC) technology. The CC power plant offers the highest thermal efficiency of all electric generating systems commercially available today. It also exhibits low capital costs, low emissions, fuel and operating flexibility, low operation and maintenance costs, short installation schedule, and high reliability/availability. However, since gas turbines (GTs) are the basis for CC power plants, these plants experience power output reductions in the range of 10 to 15 percent during summer months, the period most associated with peak power demand. In order to regain this loss of output as well as to provide additional power to meet peak demands, the most common options are GT inlet fogging, GT steam injection, and heat recovery steam generator (HRSG) supplemental firing. This paper focuses on plant design, cycle performance, and the economics of plant configuration associated with these options. Guidelines are presented in this paper to assist the owner in selecting power enhancement options for the MPP that will maximize their Return on Equity (ROE).


Author(s):  
Iacopo Rossi ◽  
Luca Piantelli ◽  
Alberto Traverso

Abstract The flexibility of power plants is a critical feature in energy production environments nowadays, due to the high share of non-dispatchable renewables. This fact dramatically increases the number of daily startups and load variations of power plants, pushing the current technologies to operate out of their optimal range. Furthermore, ambient conditions significantly influence the actual plant performance, creating deviations against the energy sold during the day-ahead and reducing the profit margins for the operators. A solution to reduce the impact of unpredicted ambient conditions, and to increase the flexibility margins of existing combined cycles, is represented by the possibility of dynamically controlling the temperature at compressor intake. At present, cooling down the compressor intake is a common practice to govern combined cycle performance in hot regions such as the Middle East and Africa, while heating up the compressor intake is commonly adopted to reduce the Minimum Environmental Load (MEL). However, such applications involve relatively slow regulation of air intake, mainly coping with extreme operating conditions. The use of continuously varying, at a relatively quick pace, the air temperature at compressor intake, to mitigate ambient condition fluctuations and to cope with electrical market requirements, involves proper modeling of the combined cycle dynamic behavior, including the short-term and long-term impacts of intake air temperature variations. This work presents a dynamic modeling framework for the whole combined cycle applied to one of IREN Energia’s Combined Cycle Units. The paper encloses the model validation against field data of the target power plant. The validated model is then used to show the potential in flexibility augmentation of properly adjusting the compressor intake temperature during operation.


Author(s):  
Kerri L. Spencer ◽  
Jeffrey R. Friedman ◽  
Terry B. Sullivan

This paper focuses on the calculation of the test uncertainty of an ASME PTC 46 [1], overall plant performance test of a combined cycle by two separate methods. It compares the combined cycle corrected plant output and heat rate systematic uncertainty results that are generated using monovariate perturbation analysis with the Monte Carlo method. The Monte Carlo method has not been used widely in power plant performance testing applications. It offers insights into the results of the Monte Carlo analysis method, which is less intuitive than the conventional method. This study shows that utilizing two distinctly different methods of calculation of test uncertainty serves to corroborate assumptions, or to isolate flaws in one or both methods. In developing the method for calculation of test uncertainty, the authors conclude that it is prudent to validate the calculation method of choice of test uncertainty, and to consider the correlations in measurement uncertainties. Also discussed in detail are the impact of correlated uncertainty assumptions, and recommendations on their application. Correlated uncertainty has not been extensively discussed in the literature concerning specific applications in performance testing, although it should be a critical consideration in any uncertainty analysis. Details of determination of instrumentation uncertainty, measurement uncertainty of a parameter, and calculation of sensitivity factors are included in this paper.


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