scholarly journals Investigations of operation problems at a 200 MWe PF boiler

2015 ◽  
Vol 36 (3) ◽  
pp. 305-320 ◽  
Author(s):  
Sandile Peta ◽  
Chris du Toit ◽  
Reshendren Naidoo ◽  
Walter Schmitz ◽  
Louis Jestin
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Integrated Approach ◽  
Combustion Efficiency ◽  
Air Distribution ◽  
Oxides Of Nitrogen ◽  
Fuel Flow ◽  
Pulverized Fuel ◽  
Air Flows ◽  
Secondary Air

Abstract To minimize oxides of nitrogen (NOx) emission, maximize boiler combustion efficiency, achieve safe and reliable burner combustion, it is crucial to master global boiler and at-the-burner control of fuel and air flows. Non-uniform pulverized fuel (PF) and air flows to burners reduce flame stability and pose risk to boiler safety by risk of reverse flue gas and fuel flow into burners. This paper presents integrated techniques implemented at pilot ESKOM power plants for the determination of global boiler air/flue gas distribution, wind-box air distribution and measures for making uniform the flow being delivered to burners within a wind-box system. This is achieved by Process Flow Modelling, at-the-burner static pressure measurements and CFD characterization. Global boiler mass and energy balances combined with validated site measurements are used in an integrated approach to calculate the total (stoichiometric + excess) air mass flow rate required to burn the coal quality being fired, determine the actual quantity of air that flows through the burners and the furnace ingress air. CFD analysis and use of at-the-burner static, total pressure and temperature measurements are utilized in a 2-pronged approach to determine root-causes for burner fires and to evaluate secondary air distribution between burners.

Thermo-Economic Analysis of Microalgae Co-Firing Process for Fossil Fuel-Fired Power Plants

2010 ◽  
Author(s):  
Jian Ma ◽  
Oliver Hemmers
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Power Plants ◽  
Fossil Fuel ◽  
Construction Materials ◽  
Ghg Emissions ◽  
Combustion Efficiency ◽  
Pure Oxygen ◽  
Firing Process ◽  
Microalgal Biomass

A thermoeconomic analysis of microalgae co-firing process for fossil fuel-fired power plants is studied. A process with closed photobioreactor and artificial illumination is evaluated for microalgae cultivation, due to its simplicity with less influence from climate variations. The results from this process would contribute to further estimation of process performance and investment. The concept of co-firing (coal-microalgae or natural gas-microalgae) includes the utilization of CO2 from power plant for microalgal biomass culture and oxy-combustion of using oxygen generated by biomass to enhance the combustion efficiency. As it reduces CO2 emission by recycling it and uses less fossil fuel, there are concomitant benefits of reduced GHG emissions. The by-products (oxygen) of microalgal biomass can be mixed with air or recycled flue gas prior to combustion, which will have the benefits of lower nitrogen oxide concentration in flue gas, higher efficiency of combustion, and not too high temperature (avoided by available construction materials) resulting from coal combustion in pure oxygen. Two case studies show that there are average savings about $0.386 million/MW/yr and $0.323 million/MW/yr for coal-fired and natural gas-fired power plants, respectively. These costs saving are economically attractive and demonstrate the promise of microalgae technology for reducing greenhouse gas (GHG) emission.

Research on Energy-Saving Control Technology of Boiler

2011 ◽  
Vol 383-390 ◽  
pp. 2603-2607
Author(s):  
Yao Yi ◽  
Guang Jian Chen ◽  
Jin Ling Jia
Keyword(s):  
Energy Saving ◽  
Intelligent Control ◽  
Flue Gas ◽  
Combustion Efficiency ◽  
Wind Pressure ◽  
Boiler Furnace ◽  
Door Opening ◽  
Boiler Efficiency ◽  
Secondary Air ◽  
Energy Saving Control

Focusing on energy-saving issues of boiler, this paper finds out the combustion conditions inside boiler furnace by monitoring and analysis on oxygen content of flue gas, carbon content of fly ash, CO and CO2 contents. The intelligent control of boiler combustion was achieved and combustion efficiency was rosen. Using neural network controlling model, automatic optimization of oxygen delivery volume,coal delivery volume, the total wind pressure of primary air, the secondary air-door opening degree and furnace negative pressure were achieved, and the boiler efficiency increasing by 5 ~ 7%.

scholarly journals OPTIMALIZATION OF AFTERBURNER CHANNEL IN BIOMASS BOILER USING CFD ANALYSIS

2016 ◽  
Vol 56 (5) ◽  
pp. 379-387 ◽  
Author(s):  
Jiří Pospíšil ◽  
Martin Lisý ◽  
Michal Špiláček
Keyword(s):  
Cross Sections ◽  
Flue Gas ◽  
Air Distribution ◽  
Cfd Analysis ◽  
Mixing Process ◽  
Rectangular Duct ◽  
Biomass Boiler ◽  
Cross Section Area ◽  
Section Area ◽  
Secondary Air

This contribution presents the results of parametrical studies focused on the mixing process in a small rectangular duct within a biomass boiler. The first study investigates the influence of a local narrowing located in the central part of the duct. This narrowing works as an orifice with very simple rectangular geometry. Four different free cross sections of the orifice were considered in the center of the duct, namely 100%, 70%, 50%, 30% of free cross section area in the duct. The second study is focused on the investigation of the influence of secondary air distribution pipe diameter on the mixing process in a flue gas duct without a narrowing.

scholarly journals Feasibility Study of Co-Firing of Torrefied Empty Fruit Bunch and Coal through Boiler Simulation

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3051
Author(s):  
Yu Jiang ◽  
Kyeong-Hoon Park ◽  
Chung-Hwan Jeon
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Power Plants ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Unburned Carbon ◽  
Empty Fruit Bunch ◽  
Oxides Of Nitrogen ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Torrefied empty fruit bunch (EFB) co-firing is a promising technology to reduce emissions from coal-fired power plants. However, co-firing can influence the combustion and heat transfer characteristics in a coal boiler. In order to study the feasibility of co-firing application of torrefied EFB (T-EFB) in boilers, the combustion characteristics, gas emissions and heat flux distribution were analyzed, respectively. First, the kinetic parameters of T-EFB devolatilization and char oxidation were obtained by experimental analysis. Second, the computational fluid dynamics (CFD) analysis was applied to the actual 500 MWe boiler simulation to further evaluate the differences in the co-firing performance parameters (combustion characteristics and emissions) of the T-EFB and the heat transfer characteristics within the boiler. Numerical results show that T-EFB co-firing can improve the ignition characteristics of pulverized coal, reduce the formation of unburned particles. When the blending ratio was increased from 10% to 50%, significantly NOx (oxides of nitrogen) reduction (levels from 170 to 98 ppm at 6% O2) was achieved. At a blending ratio above 40%, boiler combustion efficiency decreases as the total heat flux of the boiler decreases due to an increase in the amount of unburned carbon. In addition, T-EFB co-firing can affect the heat transfer characteristics of the boiler.

scholarly journals Quality Function Deployment (QFD) and TRIZ in Briquette Cookstove Design and Simulation

2021 ◽  
Vol 12 (2) ◽  
pp. 349-359
Author(s):  
Niswatun Faria ◽  
◽  
Kuntum Khoiro Ummatin ◽  
Mochammad Annas Junianto ◽  
Tedy Eko Budiharso
Keyword(s):  
Flue Gas ◽  
Quality Function Deployment ◽  
Computational Simulation ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Concept Design ◽  
Complete Combustion ◽  
Air Inlet ◽  
Secondary Air ◽  
Chamber Capacity

Poor cookstove design can harm the user's health and environment. This research aims to obtain an efficient cookstove design, environmentally friendly and operated easily. The cookstove design process using a combination of QFD and TRIZ. QFD able to capture customer needs through a questionnaire and interview. The data collected then processed to build a House of Quality (HoQ), one of the tools in QFD. QFD results in the design parameter of the briquette cookstove, which is incorporated in the concept design. The TRIZ method is utilized to understand the problem that might occur in the concept design and focus on solving the root causes. The next step is a detailed design where the dimensions, combustion chamber capacity, and supporting features are explained. The combination of QFD and TRIZ result in a briquette cookstove concept design which is easy to clean and operate. The combustion system is Top-lit Up-Draft (TLUD). The burning chamber has two air inlets, namely primary and secondary. The primary air inlet supplies the air from the bottom of the burning chamber, partially burns the briquette, and produces flue gas. The secondary air inlet is in the shape of an oval to supply air in the burning chamber's upper part to burn the flue gas completely. A complete combustion process will increase combustion efficiency and reduce emissions. A computational simulation shows the velocity distribution inside the burning chamber.

Optimization of Secondary Air Distribution in Biomass Boiler by CFD Analysis

2016 ◽  
Vol 832 ◽  
pp. 231-237 ◽  
Author(s):  
Martin Lisý ◽  
Jiří Pospíšil ◽  
Otakar Štelcl ◽  
Michal Špilaček
Keyword(s):  
Combustion Chamber ◽  
Flue Gas ◽  
Gas Flow ◽  
Air Distribution ◽  
Cfd Modelling ◽  
Biomass Boiler ◽  
Air Supply ◽  
Secondary Air ◽  
Emission Limits ◽  
The Impact

This paper deals with a use of CFD modelling for optimization of supply of secondary combustion air in the two-chamber biomass boiler combusting very wet biomass (capacity ca. 200 kW). Objective of the analyse is to observe the impact of diameter of a secondary air supply pipe and air flow velocity on mixing of the secondary air with flue gas in the combustion chamber. The numerical model of the experimental boiler was build up for subsequent utilizing of CFD computation based on finite element method. The commercial code STAR-CD was used for carried out parametrical studies. Series of calculations were carried out for four different diameters of air distribution pipes and for 3 different air velocities in distribution orifice. Quality of air dispersion in flue gas flow was assessed in the vertical cross section lead in the end of the combustion chamber. The results of calculation were verified on the experimental installation of the boiler. Influence of secondary air mixing on emission production was measured and analysed. Emissions of pollutants for recommended air distribution comply with emission limits stipulated in the most stringent class 5 according to ČSN-EN 303-5 as well as with emission limits under Regulation No. 405/2012 Sb.

Combustion Research Related to Utilization of Coal as a Gas Turbine Fuel

1984 ◽  
Vol 106 (4) ◽  
pp. 801-805
Author(s):  
D. M. Davis-Waltermire ◽  
R. J. Anderson
Keyword(s):  
Flue Gas ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Combustion Efficiency ◽  
Air Distribution ◽  
Preheat Temperature ◽  
Dependent Variables ◽  
Slurry Viscosity

A nominal 293 kw (1 MBtu/hr) atmospheric pressure, refractory-lined combustor has been used to investigate the effects of a number of combustor and fuel dependent variables on combustion efficiency and flue gas characteristics for minimally cleaned, coal-derived gas (MCG) and coal water mixtures. The variables which have been evaluted include: percent excess air, air distribution, combustion air preheat temperature, swirl number, fuel feedrate, coal particle size, coal loading in slurry, and slurry viscosity. Characterization of the flue gas included major/minor gas species, alkali levels, and particulate loading, size, and composition. These atmospheric pressure combustion studies accompanied by data from planned pressurized studies on coal-water slurries and hot, minimally cleaned, coal-derived gas will aid in the determination of the potential of these fuels for use in gas turbines.

Oxygen Enriched and Oxyfuel Combustion - Promising Trends for Low Carbon Future

2011 ◽  
Vol 145 ◽  
pp. 11-15
Author(s):  
M. Tayyeb Javed ◽  
Bill Nimmo
Keyword(s):  
Flue Gas ◽  
Line Emission ◽  
Combustion Efficiency ◽  
Base Line ◽  
Exhaust Gas ◽  
Low Carbon ◽  
No Emission ◽  
Oxyfuel Combustion ◽  
Test Conditions ◽  
Secondary Air

The escalation of ambient CO2 concentration due excessive use of coal in power generation has put impetus on the development of technologies for utilization of vast and cheap resources available through out the world. Eco-scrub, Oxygen enriched and oxyfuel combustion are among the promising technologies guaranteeing the low carbon future. In our recent investigations, pulverized coal (Russian) was fired in a 20 kW down fired combustion rig under simulated exhaust gas recirculation. The effect of CO2 at burner inlet on the combustion efficiency, flue gas CO2 and NO emission was studied. The test conditions were essentially achieved by replacing the secondary air with a mixture of O2 and CO2 in different proportion. The test conditions do imitate the four key conditions for eco-scrub project. The basic theme under eco-scrub project is to use limited oxygen addition to reduce the volume of flue gas for processing, increase the efficiency of post combustion scrubbing due to higher CO2 levels and reduced the size and cost of post combustion capture. The exhaust gas CO2 was observed to increase linearly with increasing the CO2 at burner inlet. The flue gas concentration for 35% and 45% flue gas recycle was recorded to be 24% and 30% respectively. The NO emission was most of the time under the base line emission of 818 ppm. A maximum of 66% reduction was observed when the burner inlet CO2 was 45% and 21% O2. How ever an increase of 37% was seen when 80% of the secondary air was replaced with a 50%O2-50%CO2 mixture.

scholarly journals NOx Emission Reduction in Flue Gas of Coal Fired Thermal Power Station and its Control Measures by Secondary Measures

2019 ◽  
Vol 9 (2S4) ◽  
pp. 83-88
Keyword(s):  
Flue Gas ◽  
Emission Reduction ◽  
Power Plants ◽  
Thermal Power ◽  
Carbonaceous Material ◽  
Control Measures ◽  
Nox Emission ◽  
Total Power ◽  
Oxides Of Nitrogen ◽  
Permissible Limits

The ever increasing demand for power is mostly met out by electricity produced with the available resources. One such source where generation of power is by making use of the fossil fuel such as coal. Thermal generation using coal accounts for 69% of the total power produced in India. Flue Gases emitted from coal fired thermal stations consists of CO2,(Carbon-di-oxide),SOx (Oxides of Sulphur), NOx (Oxides of Nitrogen), PM (Particulate matter) along with carbonaceous material, soot and Fly ash. These gaseous pollutants are considered as environmental burden which ultimately results in smog formation, formation of acid rain, eutrophication and global warming which has to be controlled and regulated within the permissible limits as stipulated by MOEF &CC (Ministry of Environmental Forest and Climate Change). This project describes about the analysis of reduction of NOx Emission in Flue Gas of Coal fired thermal stations and the measures to control the NOx emission within the permissible limits for the new thermal power plants by treating the flue gas emitted from the stack. The secondary measure to reduce the NOx emission is achieved by treating the flue gas with urea or ammonia which bring about 90% NOx emission reduction. The application of Low Nox Burner with Over Fire Air Technology along with Selective Catalytic Reduction in the new thermal power plant reduce the emission of NOx to a considerable extent and to meet the norms

scholarly journals Development of Flue Gas Desulphurization Reactor for Reducing SOX Emission from Flue Gases Emitted in Thermal Power Plants

2019 ◽  
Vol 9 (2S4) ◽  
pp. 89-95
Keyword(s):  
Power Plant ◽  
Flue Gas ◽  
Power Plants ◽  
Thermal Power ◽  
Electrical Energy ◽  
Oxides Of Nitrogen ◽  
Power Station ◽  
Contamination Control ◽  
Power Stations ◽  
Oil Gas

Electrical energy produced in any country is one of the development measures takes place in that country. The energy produced is mainly based on the available resources such as flowing water, coal, oil, gas, nuclear fuels, wind, solar etc. The accessibility of bounty coal in India had provoked the power plant organizers to introduce coal based warm power stations. During the pre-autonomy and post-freedom period in mid fifties, the need was to create control and subsequently much consideration was not paid to the contamination angle and this proceeded up to late seventies. The awareness made by contamination impact on the general public and the colossal measure of disintegration exposed to the gear constrained the specialists to make contamination standards increasingly stringent. These convincing standards which appeared in eighties required the power plant faculty to change the contamination control gear in the current power plants introduced during early days. Most of intensity plants in India going from not many MW to 500 MW or more are of pounded fuel terminated boilers using low calorific, low coal sulfur, high debris content sub-bituminous coal. Due to burning of the coal, emissions such as Particulate Matter (PM), Oxides of Sulphur (SOx) and Oxides of Nitrogen (NOx) apart from CO2, CO are carried away to the atmosphere through the flue gas. In this paper, the methodology to reduce SOx from flue gas in a coastal power station in is discussed and the optimum methodology adopted is Seawater Flue Gas Desulphurisation (SWFGD) using the alkalinity of the seawater to scrub SO2 from the flue gas. The seawater used in the FGD system is from the once through Condenser outlet of the Turbine system and since there is no by-product to be disposed, the seawater FGD is the optimum SOx reducing mechanism for a coastal thermal power station.

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