scholarly journals Next-generation, affordable SO2 abatement for coal-fired power generation - A comparison of limestone-based wet flue gas desulphurization and Sulfacid® technologies for Medupi power station

2020 ◽  
Vol 120 (10) ◽  
Author(s):  
A. Strickroth ◽  
M. Schumacher ◽  
G.W. Hasse ◽  
I. Kgomo
Keyword(s):  
Power Generation ◽  
Sulphuric Acid ◽  
Flue Gas ◽  
Coal Ash ◽  
Poor Quality ◽  
Steam Generation ◽  
So2 Emissions ◽  
Process Technology ◽  
Power Station ◽  
Flue Gas Desulphurization

SYNOPSIS Coal is used to generate more than three-quarters of South Africa's electricity, while numerous coal-fired boilers are employed for steam generation in industrial processes. However, coal-fired power generation is responsible for the release of the largest quantities of SO2 emissions to the atmosphere and leads to detrimental health and welfare effects in communities in the proximity of coal-fired plants. The classical industrial SO2 abatement solution for the coal-fired power generation industry is wet flue gas desulphurization, which uses a limestone adsorbent and produces a gypsum by-product (WFGD L/G). In South Africa, due to the poor quality of the limestone the gypsum product is unsaleable and is co-disposed with coal ash. In comparison, the Sulfacid® process technology converts SO2 contained in industrial flue gas into saleable sulphuric acid using a catalytic process requiring only water and air. This process does not require limestone. The scale of the latest commercial applications of the Sulfacid® SO2 abatement technology in the chemical, fertilizer, and copper mining industries demonstrates the potential and readiness of this technology to be employed in the coal-fired electricity and steam production sectors. This paper provides a first-order direct comparison between the techno-economic aspects of the WFGD (L/G) and Sulfacid® technologies using the requirements specified for the 6 x 800 MWe Eskom coal-fired Medupi power station. The results indicate that affordable flue gas desulphurization technology exists that could be adopted by the South African industry to reduce SO2 emissions to legislative limits and beyond. Keywords: SO2 abatement, coal-fired power, and heat generation, sulphuric acid, wet fluidized gas desulphurization, Sulfacid®, waste-to-chemicals.

Reassessment of the environmental impacts of sulphur oxide emissions from power stations

2013 ◽  
Vol 24 (2) ◽  
pp. 28-36 ◽  
Author(s):  
Philip Lloyd
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Reliable Data ◽  
External Costs ◽  
Power Station ◽  
Sulphur Compounds ◽  
Sulphur Oxide ◽  
Power Stations ◽  
Sulphur Emissions ◽  
Negative Impacts

It is a deeply entrenched belief that emissions of sulphur dioxide into the atmosphere are harmful to the environment, and that sulphur compounds should be removed from the gaseous wastes before discharge. The difficulties with this view are summarised. Extensive work in both North America and Europe has failed to demonstrate any of the early claims for impacts such as forest death. The claims for health effects seem unduly conservative and not supported by reliable data. There are even negative impacts from reducing sulphur emissions. Claims for high external costs associated with coal-fired power generation in South Africa are the result of arithmetic errors. The installation of flue-gas desulphurisation on the latest Eskom power station, Kusile, is shown to be completely unsustainable in the light of the minimal benefits that the considerable costs will bring.

Could biomass-fueled boilers be operated at higher steam temperatures? Part 3: Initial analysis of costs and benefits

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 65-78 ◽  
Author(s):  
W.B.A. (SANDY) SHARP ◽  
W.J. JIM FREDERICK ◽  
JAMES R. KEISER ◽  
DOUGLAS L. SINGBEIL
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Superheated Steam ◽  
Black Liquor ◽  
Simulation Software ◽  
Operating Conditions ◽  
Costs And Benefits ◽  
Steam Generation ◽  
Fireside Corrosion ◽  
Corrosion Resistant

The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented, and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100°C above current operating conditions ranges between US$2,410,000 and US$11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys; redesigning biomassfueled boilers to remove the superheater from the flue gas path; or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.

The Properties of Flue Gas Desulphurization (FGD) Gypsum

2011 ◽  
Vol 105-107 ◽  
pp. 2204-2208 ◽  
Author(s):  
Run Xia Hao ◽  
Xiao Yan Guo
Keyword(s):  
Mechanical Properties ◽  
Flue Gas ◽  
Steel Slag ◽  
Optical Microscope ◽  
Cementitious Material ◽  
Fgd Gypsum ◽  
Technical Performance ◽  
Slag Powder ◽  
Steel Slag Powder ◽  
Flue Gas Desulphurization

The properties of flue gas desulphurization (FGD) gypsum were analysized by Thermo-gravimetry/differential scanning calorimetry (TG/DSC), technical performance analysis, optical microscope and Scanning electron microscope (SEM). Mechanical properties of FGD gypsum-steel slag powder cementitious material were researched. The results revealed that FGD gypsum have similar moisture content, major component CaSO4·2H2O with natural gypsum, and has better technical performance than natural gypsum. The results of optical microscope and SEM of the FGD gypsum hydration support this further. When the dosage of steel slag powder is 15%, containing activator ,better mechanical properties can be obtained. Key words: FGD gypsum, Property, Cementitious material

NOx process inhibition and energy efficiency improvement in new swirl modification device for steel slag based on coal combustion

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Junxiang Guo ◽  
Lingling Zhang ◽  
Daqiang Cang ◽  
Liying Qi ◽  
Wenbin Dai ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Flue Gas ◽  
Coal Combustion ◽  
Steel Slag ◽  
Coal Ash ◽  
Combustion Efficiency ◽  
Gas Temperature ◽  
Staged Combustion ◽  
Energy Efficiency Improvement ◽  
Swirl Combustion

Abstract In this study, a novel swirl combustion modified device for steel slag was designed and enhanced with the objective of achieving highly efficient and clean coal combustion and also for achieving the whole elements utilization of coal. Coal ash and steel slag were melted in the combustion chamber and subsequently entered the slag chamber. The detrimental substances solidified and formed crystals, which allowed for the comprehensive utilization of the ash and slag. Our experiments mainly aimed to mitigate the formation of NOx, while using the heat and slag simultaneously during the coal combustion without a combustion efficiency penalty. The increase in the device’s energy efficiency and reduction in the NOx emissions are important requirements for industrialization. The experiments were carried out in an optimized swirling combustion device, which had a different structure and various coal feeding conditions in comparison to previously reported devices. The fuel-staged and non-staged combustion experiments were compared under different coal ratios (bitumite:anthracite). For the fuel-staged combustion experiments, the NOx concentration in the flue gas was observed to decrease significantly when the coal ratio of 1:1, an excess air coefficient of 1.2, and a fuel-staged ratio of 15:85 were used. Under these conditions, the flue gas temperature was as high as 1,620°C, while the NOx concentration was as low as 320 mg/m3 at 6 % O2. The air-surrounding-fuel structure that formed in the furnace was very beneficial in reducing the formation of NOx. In comparison to other types of coal burners, the experimental combustion device designed in this study achieved a significant reduction of NOx emissions (approximately 80 %).

Seawater Scrubbing for the Removal of Sulfur Dioxide in a Steam Turbine Power Plant

2005 ◽  
Author(s):  
Akili D. Khawaji ◽  
Jong-Mihn Wie
Keyword(s):  
Power Plant ◽  
Sulfur Dioxide ◽  
Steam Turbine ◽  
Flue Gas ◽  
Operating Cost ◽  
Cooling Water ◽  
Cost Savings ◽  
Fuel Oil ◽  
So2 Emissions ◽  
Heavy Fuel Oil

The most popular method of controlling sulfur dioxide (SO2) emissions in a steam turbine power plant is a flue gas desulfurization (FGD) process that uses lime/limestone scrubbing. Another relatively newer FGD technology is to use seawater as a scrubbing medium to absorb SO2 by utilizing the alkalinity present in seawater. This seawater scrubbing FGD process is viable and attractive when a sufficient quantity of seawater is available as a spent cooling water within reasonable proximity to the FGD scrubber. In this process the SO2 gas in the flue gas is absorbed by seawater in an absorber and subsequently oxidized to sulfate by additional seawater. The benefits of the seawater FGD process over the lime/limestone process and other processes are; 1) The process does not require reagents for scrubbing as only seawater and air are needed, thereby reducing the plant operating cost significantly, and 2) No solid waste and sludge are generated, eliminating waste disposal, resulting in substantial cost savings and increasing plant operating reliability. This paper reviews the thermodynamic aspects of the SO2 and seawater system, basic process principles and chemistry, major unit operations consisting of absorption, oxidation and neutralization, plant operation and performance, cost estimates for a typical seawater FGD plant, and pertinent environmental issues and impacts. In addition, the paper presents the major design features of a seawater FGD scrubber for the 130 MW oil fired steam turbine power plant that is under construction in Madinat Yanbu Al-Sinaiyah, Saudi Arabia. The scrubber with the power plant designed for burning heavy fuel oil containing 4% sulfur by weight, is designed to reduce the SO2 level in flue gas to 425 ng/J from 1,957 ng/J.

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