A Survey on Intelligent Optimization Approaches to Boiler Combustion Optimization

This paper reviews the researches on boiler combustion optimization, which is an important direction in the field of energy saving and emission reduction. Many methods have been used to deal with boiler combustion optimization, among which evolutionary computing (EC) techniques have recently gained much attention. However, the existing researches are not sufficiently focused and have not been summarized systematically. This has led to slow progress of research on boiler combustion optimization and has obstacles in the application. This paper introduces a comprehensive survey of the works of intelligent optimization algorithms in boiler combustion optimization and summarizes the contributions of different optimization algorithms. Finally, this paper discusses new research challenges and outlines future research directions, which can guide boiler combustion optimization to improve energy efficiency and reduce pollutant emission concentrations

Environmental Analysis, Monitoring, and Process Control Strategy for Reduction of Greenhouse Gaseous Emissions in Thermochemical Reactions

This review paper illustrates the recommended monitoring technologies for the detection of various greenhouse gaseous emissions for solid waste thermochemical reactions, including incineration, pyrolysis, and gasification. The illustrated gas analyzers are based on the absorption principle, which continuously measures the physicochemical properties of gaseous mixtures, including oxygen, carbon dioxide, carbon monoxide, hydrogen, and methane, during thermochemical reactions. This paper illustrates the recommended gas analyzers and process control tools for different thermochemical reactions and aims to recommend equipment to increase the sensitivity, linearity, and dynamics of various thermochemical reactions. The equipment achieves new levels of on-location, real-time analytical capability using FTIR analysis. The environmental assessment study includes inventory analysis, impact analysis, and sensitivity analysis to compare the mentioned solid waste chemical recycling methods in terms of greenhouse gaseous emissions, thermal efficiency, electrical efficiency, and sensitivity analysis. The environmental impact assessment compares each technology in terms of greenhouse gaseous emissions, including CO2, NOx, NH3, N2O, CO, CH4, heat, and electricity generation. The conducted environmental assessment compares the mentioned technologies through 15 different emission-related impact categories, including climate change impact, ecosystem quality, and resource depletion. The continuously monitored process streams assure the online monitoring of gaseous products of thermochemical processes that enhance the quality of the end products and reduce undesired products, such as tar and char. This state-of-the-art monitoring and process control framework provides recommended analytical equipment and monitoring tools for different thermochemical reactions to optimize process parameters and reduce greenhouse gaseous emissions and undesired products

Parametric study of prospective early commercial MHD power plants (PSPEC). General Electric Company, task 1: Parametric analysis

The performance and cost of moderate technology coal-fired open cycle MHD/steam power plant designs which can be expected to require a shorter development time and have a lower development cost than previously considered mature OCMHD/steam plants were determined. Three base cases were considered: an indirectly-fired high temperature air heater (HTAH) subsystem delivering air at 2700 F, fired by a state of the art atmospheric pressure gasifier, and the HTAH subsystem was deleted and oxygen enrichment was used to obtain requisite MHD combustion temperature. Coal pile to bus bar efficiencies in ease case 1 ranged from 41.4% to 42.9%, and cost of electricity (COE) was highest of the three base cases. For base case 2 the efficiency range was 42.0% to 45.6%, and COE was lowest. For base case 3 the efficiency range was 42.9% to 44.4%, and COE was intermediate. The best parametric cases in bases cases 2 and 3 are recommended for conceptual design. Eventual choice between these approaches is dependent on further evaluation of the tradeoffs among HTAH development risk, O2 plant integration, and further refinements of comparative costs

ECOS 2012

The 8-volume set contains the Proceedings of the 25th ECOS 2012 International Conference, Perugia, Italy, June 26th to June 29th, 2012. ECOS is an acronym for Efficiency, Cost, Optimization and Simulation (of energy conversion systems and processes), summarizing the topics covered in ECOS: Thermodynamics, Heat and Mass Transfer, Exergy and Second Law Analysis, Process Integration and Heat Exchanger Networks, Fluid Dynamics and Power Plant Components, Fuel Cells, Simulation of Energy Conversion Systems, Renewable Energies, Thermo-Economic Analysis and Optimisation, Combustion, Chemical Reactors, Carbon Capture and Sequestration, Building/Urban/Complex Energy Systems, Water Desalination and Use of Water Resources, Energy Systems- Environmental and Sustainability Issues, System Operation/ Control/Diagnosis and Prognosis, Industrial Ecology

Investigation into fly ash production during co-firing of biomass with pulverized coal

This dissertation considers the behaviour of particulate fly ash produced during cocombustion experiments of biomass materials with pulverized coal in a 1 MWth pilotscale combustion test facility (PSCTF). Particular attention is generally given to fly ash particles of diameters less than 10 and 2.5 microns (namely PM10 and PM2.5). These small particles have the potential for affecting human health and forcing climate change because of their ability to scatter and absorb light and also to act as cloud condensation nuclei. South African coal has high ash content that consequently affects the ash burden and the efficiency of ash removal system. Previous research work reports increase of the concentration of fine particles during the co-firing of biomass with coal, thus limiting the amount of biomass co-fired. Coal and two types of biomass, grass and sawdust, were used in this study. The coal chosen was representative on the basis of the annual average calorific value of coals burned at ESKOM’S coal-fired power stations. For each biomass, the ratios of biomass to coal used on an energy basis were 10%:90%, 15%:85% and 20%:80%, resulting in a total of seven different tests including coal alone. Seven tests with similar fuels were also carried out using a drop tube furnace (DTF) to determine their reaction kinetics for the combustion simulation. The experimental results revealed that the grass and sawdust blends showed decreases of PM10, and PM2.5 particles percentages compared to the coal baseline. The grass because of its high content of alumina-silicate showed considerable agglomeration whereas sawdust blends gave minor increase of PM10 under high pressure condition inside the combustion chamber. The pulverised-coal fineness, flue gas temperature and excess air were found to affect the particulate matter behaviour. The fly ash samples collected were also analysed by scanning electron microscope and spectrometry; alkali metals released were observed to react with the alumino-silicate phase. The fine sulphate enriched particles formation during combustion process was 4 modelled based on the Glarborg-Marshall mechanism using CFD tool. The simulation results were validated by the experimental data from the pilot-scale combustion test facility

Reaction mechanism of N0x destruction by non-thermal plasma discharge, 1999

Nitrogen oxides (NOx) contribute to the formation of acid rain and ground-level ozone. Cost-effective technologies that destroy NOx from gas stReams are needed. Of particular interest are Non-thermal plasma technologies that offer an innovative approach to the solution of NOx emission control. This study investigates the use of a particular electrical discharge technique, the barrier discharge. Experiments were conducted in double dielectric barrier discharge (DDBD) reactors to elucidate the effects of physical and chemical variables on the NOx removal efficiencies. Analysis instruments included a FT-IR with a length adjustable gas cell, a GC-ms, several gas analyzers and an emission spectrometer. The variables investigated include input power, chemical composition, residence time, and gap spacing. Through this investigation, an overall optimization of DDBD performance was obtained. Of these, we primarily investigated the effect of discharge gap spacing on the electrical and chemical processes that occur in non-thermal plasma discharge (NTPD). A numerical model was developed to simulate the physical and chemical processes during the oxidation and reduction of NOx. Experiments and 1 calculations were performed to investigate the effects of the above-mentioned variables on breakdown electric field, free electron energy distribution, electron impact kinetic rates, and chemical reactions. Results from the calculations and experiments demonstrated the complex relations between NOx removal efficiency and the tested variables. A mechanism of NOx destruction in a NTPD was proposed. This study revealed that the characteristics of microdischarges are the key to understanding the NTPD process. Optical measurements, by means of a high speed intensified imager, provided important information on the microdischarge. This information helped to develop the numerical model, which established the relation between surface charge and charge density within a microdischarge. Results of this study should provide a basis for developing a potential solution for the reduction of NOx emission from off-gas sources, such as diesel-powered aerospace ground equipment used on the Air Force

Online Laser Diagnostics for High-Temperature Chemistry in Biomass Combustion

Increasing concern over environment and new energy policies are driving the thermal heat and power industry towards new CO2 neutral fuels, such as biomass, and novel combustion schemes. Therefore new operational control and monitoring concepts are required to provide information of the combustion processes. Alkali elements and compounds have been identified to be one of the greatest challenges associated with thermal conversion of biomass as they cause severe operational problems in power plant boilers. In this Thesis, a new method to monitor temperature and O2 concentration during thermal conversion of biomass is developed. Collinear Photofragmentation and Atomic Absorption Spectroscopy (CPFAAS) is utilized to measure potassium reaction kinetics in lean combustion conditions, which provides valuable information for high temperature reaction models and simulations. The new information on potassium reaction kinetics with O2 enables online monitoring of temperature and O2 concentration utilizing the CPFAAS signal.Microwave-Assisted Laser-Induced Breakdown Spectroscopy (MW-LIBS) is demonstrated for the first time at ambient atmospheric conditions with impressive 93fold enhancement in limit of detection (LOD). MW-LIBS is further applied for online elemental monitoring during thermal conversion of biomass fuels as it improves detection of trace elements and reduces adverse self-absorption effects in high-concentration conditions. To enable the benefits of MW-LIBS, a novel burner for flame calibration is introduced. The burner allows calibration of LIBS for extended concentration range enabling quantitative elemental release monitoring during thermal conversion of different biomass fuels with varying elemental content. The elemental release behavior of biomass fuels is paramount for thermal conversion models and simulations that provide boiler operators and manufacturers crucial information on how to optimize the thermal processes and mitigate the alkali associated problems. Furthermore, as the novel MW-LIBS approach requires no or minimal sample preparation, it has great application potential for online elemental monitoring in different fields of science where low LOD or high sensitivity is required.The novel CPFAAS and MW-LIBS approaches provide simple and versatile methods for online high-temperature chemistry monitoring from laboratory-scale systems up to full-scale power plant boilers. Laser diagnostics will play a significant role in optimization and in process control of future thermal power generation as it enables development of online sensor networks to monitor and forecast the plant behavior

Energy: A continuing bibliography with indexes, issue 13

This bibliography lists 1036 reports, articles, and other documents introduced into the NASA scientific and technical information system from January 1, 1977 through March 31, 1977