Monitoring and Improving Coal-Fired Power Plants Using the Input/Loss Method: Part IV

Author(s):  
Fred D. Lang

The Input/Loss Method is a unique process which allows for complete thermal understanding of a power plant through explicit determinations of fuel chemistry including fuel water and mineral matter, fuel heating (calorific) value, As-Fired fuel flow, effluent flow, boiler efficiency and system heat rate. Input consists of routine plant data and any parameter which effects system stoichiometrics, including: Stack CO2, Boiler or Stack O2, and, generally, Stack H2O. It is intended for on-line monitoring of coal-fired systems; effluent flow is not measured, plant indicated fuel flow is typically used only for comparison to the computed. The base technology of the Input/Loss Method was documented in companion ASME papers: Parts I, II and III (IJPGC 1998-Pwr-33, IJPGC 1999-Pwr-34 and IJPGC 2000-15079/CD). The Input/Loss Method is protected by US and foreign patents (1994–2004). This Part IV presents details of the Method’s ability to correct any data which effects system stoichiometrics, data obtained either by direct measurements or by assumptions, using multi-dimensional minimization techniques. This is termed the Error Analysis feature of the Input/Loss Method. Addressing errors in combustion effluent measurements is of critical importance for any practical on-line monitoring of a coal-fired unit in which fuel chemistry is being computed. It is based, in part, on an “L Factor” which has been proven to be remarkably constant for a given source of coal; and, indeed, even constant for entire Ranks. The Error Analysis feature assures that every computed fuel chemistry is the most applicable for a given set of system stoichiometrics and effluents. In addition, this paper presents comparisons of computed heating values to grab samples obtained from train deliveries. Such comparisons would not be possible without the Error Analysis.

Author(s):  
Fred D. Lang

This paper presents generic methods for verifying online monitoring systems associated with coal-fired power plants. It is applicable to any on-line system. The methods fundamentally recognize that if coal-fired unite are to be understood, that system stoichiometrics must be understood in real-time, this implies that fuel chemistry must be understood in real-time. No accurate boiler efficiency can be determined without fuel chemistry, heating value and boundary conditions. From such fundamentals, four specific techniques are described, all based on an understanding (or not) of real-time system stoichiometrics. The specific techniques include: 1) comparing a computed ambient relative humidity which satisfies system stoichiometrics, to a directly measured value; 2) comparing a computed water/steam soot blowing flow which satisfies system stoichiometrics, to a directly measured value; 3) comparing computed Energy or Flow Compensators (based on computed boiler efficiency, heating value, etc.), to the unit’s DCS values; and 4) comparing a computed fuel flow rate, based on boiler efficiency, to the plant’s indication of fuel flow. Although developed using the Input/Loss Method, the presented methods can be applied to any online monitoring system such that verification of computed results can be had in real-time. If results agree with measured values, within defined error bands, the system is said to be understood and verified; from this, heat rate improvement will follow. This work has demonstrated that use of ambient relative humidity is a viable verification tool. Given its influence on system stoichiometrics, use of relative humidity immediately suggests that effluent (Stack) flow can be verified against an independently measured parameter which has nothing to do with coal-fired combustion per se. Whether an understanding of coal-fired combustion is believed to be in-hand, or not, use of relative humidity (and, indeed, soot blowing flow) provides the means for verifying the actual and absolute carbon and sulfur emission mass flow rates. Such knowledge should prove useful given emission taxes or an imposed cap and trade system. Of the four methods examined, success was not universal; notably any use of plant indicated fuel flow (as would be expected) must be employed with caution. Although applicable to any system, the Input/Loss Method was used for development of these methods. Input/Loss is a unique process which allows for complete understanding of a coal-fired power plant through explicit determinations of fuel chemistry including fuel water and mineral matter, fuel heating (calorific) value, As-Fired fuel flow, effluent flow, boiler efficiency and system heat rate. Input consists of routine plant data and any parameter which effects stoichiometrics, typically: effluent CO2, O2 and, generally, effluent H2O. The base technology of the Input/Loss Method has been documented in companion ASME papers, Parts I thru IV, which addressed topics of base formulations, benchmarking fuel chemistry calculations, high accuracy boiler efficiency methods and correcting instrumentation errors in those terms affecting system stoichiometric (e.g., CEMS and other data).


Author(s):  
Fred D. Lang ◽  
David A. T. Rodgers ◽  
Loren E. Mayer

This paper presents an on-line method which detects steam generator tube leaks and the heat exchanger in which the leak occurs. This method (the Tube Failure Model) has been demonstrated by direct testing experience. It is based on the Input/Loss Method, a patented method (1994–2004) which computes fuel chemistry, heating value and fuel flow by integrating effluent measurements (CEMS data) with thermodynamics. This paper explains the technology supporting the detection of tube failures, the method of identifying the location of the failure, and cites direct experience of detecting tube failures at two power plants. Most importantly, this paper presents the results of direct testing at the Boardman Coal Plant in which high energy steam/water lines were routed from the drain headers of all major heat exchangers into the combustion space. When allowed flow, these lines were used to emulate tube leaks from any of the major heat exchangers. Their flow rates and locations were then compared to Tube Failure Model predications. This testing is considered significant as for the first time Δheat rate effects of tube failures will be directly determined; and, further, this testing will provide the Tube Failure Model its on-line proof-of-process.


Author(s):  
J. Kubiak S. ◽  
G. Urquiza B. ◽  
A. Garci´a-Gutierrez

This paper describes the development of an Expert System for identification of generating equipment faults caused by wearing out of their components, which decrease the efficiency and thus the heat rate of a generating plant. In a sister paper [1], the formulation was presented and the algorithms for the principal equipment were developed. The Expert Systems are based on the above algorithms. Also, in some case a vibration analysis is used jointly with thermodynamic analysis to locate precisely a fault, for example in a case of rubbing which damaged the seals of the turbine and/or compressors. The system is used off-line, however it can be installed on-line with a monitoring system. The Expert Systems identify the faults of the gas turbine, the compressor and the steam turbine. Auxiliary equipment faults are presented in the form of tables also, listing the symptoms and their causes [1]. The knowledge levels and the separate bases are built into the systems.


Author(s):  
David A. T. Rodgers ◽  
Fred D. Lang

This paper presents methods and practices of improving heat rate through testing and, most importantly, through heat rate monitoring. This work was preformed at Portland General Electric’s 585 MWe Boardman Coal Plant, which used two very different Powder River Basin and Utah coals ranging from 8,100 to over 12,500 Btu/lbm. Such fuel variability, common now among coal-fired units was successfully addressed by Boardman’s on-line monitoring techniques. Monitoring has evolved over the past ten years from a Controllable Parameters approach (offering disconnected guidance), to a systems approach in which fuel chemistry and heating value are determined on-line, their results serving as a bases for Second Law analysis. At Boardman on-line monitoring was implemented through Exergetic System’s Input/Loss Method. Boardman was one of the first half-dozen plants to fully implement Input/Loss. This paper teaches through discussion of eight in-plant examples. These examples discuss heat rate improvements involving both operational configurations and plant components: from determining changes in coal chemistry and composite heating value on-line; to recognizing the impact of individual rows of burners and pulverizer configurations; to air leakage identifications; to examples of hour-by-hour heat rate improvements; comparison to effluent flows; etc. All of these cases have applicability to any coal-fired unit.


2021 ◽  
Vol 882 (1) ◽  
pp. 012033
Author(s):  
Eko Supriyanto ◽  
Nur Cahyo ◽  
Ruly Sitanggang ◽  
Rasgianti ◽  
Meiri Triani ◽  
...  

Abstract In a coal steam power plant, changes in coal quality significantly affect plant performance, especially in its boiler. A coal-fired power plant with a capacity of 400 MWe had been commissioned using coal with a calorific value of 5,242 kCal/kg. This study aims to determine the effect on unit performance and boiler efficiency due to changes in fuel use with the typical calorific value of 3,520 kCal/kg, 34,17% lower than the initial design. The performance tests were conducted using the heat loss method at loads: 50%, 65%, 75%, and 100%. The test result showed that using low-grade coal reduces boiler efficiency by 6.26%. There were four dominant boiler losses: heat loss due to moisture in dry flue gas, heat loss due to combustible in refuse, heat loss due to moisture in fuel, and heat loss due to hydrogen burning. Furthermore, the gross plant heat rate using low-grade coal was increased from 2,120 kCal/kWh to 2,718 kCal/kWh; however, the electric price becomes cheaper from 1.99 cent-USD/kWh becomes 1.31 cent-USD/kWh.


Author(s):  
Fred D. Lang

This paper presents an method for heat rate monitoring of power plants which employs a true “systems approach”. As an ultimate monitoring parameter, derived from Second Law concepts, it quantifies system losses in terms of fuel consumption by individual components and processes. If electricity is to be produced with the least un-productive fuel consumption, then thermodynamic losses must be understood and minimized. Such understanding cuts across vendor curves, plant design, fuels, Controllable Parameters, etc. This paper demonstrates that thermal losses in a nuclear unit and a trash burner are comparable at a prime facia level. The Second Law offers the only foundation for the study of such losses, and affords the bases for a true and ultimate indicator of system performance. From such foundations, a Fuel Consumption Index (FCI) was developed to indicate specifically what components or processes are thermodynamically responsible for fuel consumption. FCIs tell the performance engineer why fuel is being consumed, quantifying that a portion of fuel which must be consumed to overcome frictional dissipation in the turbine cycle (FCITCycle), the combustion process (FCIComb), and so forth; and, indeed, how much fuel is required for the direct generation of electricity (FCIPower). FCIs have been particularly applicable for monitoring power plants using the Input/Loss Method. FCIs, Δheat rates based on FCIs, and an “applicability indicator” for justifying the use of Reference Bogey Data are all defined. This paper also presents the concept of “dynamic heat rate”, based on FCIs, as a parameter by which the power plant operator can gain immediate feedback as to which direction his actions are thermally headed: towards a lower or higher heat rate.


Author(s):  
Rodney R. Gay

Traditionally optimization has been thought of as a technology to set power plant controllable parameters (i.e. gas turbine power levels, duct burner fuel flows, auxiliary boiler fuel flows or bypass/letdown flows) so as to maximize plant operations. However, there are additional applications of optimizer technology that may be even more beneficial than simply finding the best control settings for current operation. Most smaller, simpler power plants (such as a single gas turbine in combined cycle operation) perceive little need for on-line optimization, but in fact could benefit significantly from the application of optimizer technology. An optimizer must contain a mathematical model of the power plant performance and of the economic revenue and cost streams associated with the plant. This model can be exercised in the “what-if” mode to supply valuable on-line information to the plant operators. The following quantities can be calculated: Target Heat Rate Correction of Current Plant Operation to Guarantee Conditions Current Power Generation Capacity (Availability) Average Cost of a Megawatt Produced Cost of Last Megawatt Cost of Process Steam Produced Cost of Last Pound of Process Steam Heat Rate Increment Due to Load Change Prediction of Future Power Generation Capability (24 Hour Prediction) Prediction of Future Fuel Consumption (24 Hour Prediction) Impact of Equipment Operational Constraints Impact of Maintenance Actions Plant Budget Analysis Comparison of Various Operational Strategies Over Time Evaluation of Plant Upgrades The paper describes examples of optimizer applications other than the on-line computation of control setting that have provided benefit to plant operators. Actual plant data will be used to illustrate the examples.


Author(s):  
Fred D. Lang ◽  
Tom Canning

This paper asserts a new method of analyzing fossil fuels, useful for sorting coals into well defined categories and for the identification of outlying ultimate analysis data. It describes a series of techniques starting with a new multi-variant approach for describing the lower Ranks of coal, progressing to a classical, but modified, single-variant approach for the volatile and high energy Ranks. In addition, for a few special cases, multiple low and high Ranks are also well described by the multi-variant approach. As useful as these techniques are for analyzing fuel chemistry in the laboratory arena, this work was initiated in support of Exergetic Systems’ Input/Loss Method. At commercial coal-fired power plants, Input/Loss allows the determination of fuel chemistry based on combustion effluents. The methods presented allow equations to be developed independent of combustion stoichiometrics, which improve Input/Loss accuracy in determining fuel chemistry on-line and in real time.


Author(s):  
O. M. Salamov ◽  
F. F. Aliyev

The paper discusses the possibility of obtaining liquid and gaseous fuels from different types of biomass (BM) and combustible solid waste (CSW) of various origins. The available world reserves of traditional types of fuel are analyzed and a number of environmental shortcomings that created during their use are indicated. The tables present the data on the conditional calorific value (CCV) of the main traditional and alternative types of solid, liquid and gaseous fuels which compared with CCV of various types of BM and CSW. Possible methods for utilization of BM and CSW are analyzed, as well as the methods for converting them into alternative types of fuel, especially into combustible gases.Reliable information is given on the available oil and gas reserves in Azerbaijan. As a result of the research, it was revealed that the currently available oil reserves of Azerbaijan can completely dry out after 33.5 years, and gas reserves–after 117 years, without taking into account the growth rates of the exported part of these fuels to European countries. In order to fix this situation, first of all it is necessary to use as much as possible alternative and renewable energy sources, especially wind power plants (WPP) and solar photovoltaic energy sources (SFES) in the energy sector of the republic. Azerbaijan has large reserves of solar and wind energy. In addition, all regions of the country have large reserves of BM, and in the big cities, especially in industrial ones, there are CSW from which through pyrolysis and gasification is possible to obtain a high-quality combustible gas mixture, comprising: H2 + CO + CH4, with the least amount of harmful waste. The remains of the reaction of thermochemical decomposition of BM and CSW to combustible gases can also be used as mineral fertilizers in agriculture. The available and projected resources of Azerbaijan for the BM and the CSW are given, as well as their assumed energy intensity in the energy sector of the republic.Given the high energy intensity of the pyrolysis and gasification of the BM and CSW, at the present time for carrying out these reactions, the high-temperature solar installations with limited power are used as energy sources, and further preference is given to the use of WPP and SFES on industrial scale.


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