Process Simulation of Oxy-Fuel Combustion for A 120 MW Coal-Fired Power Plant Using Aspen Plus

Oxy-fuel Combustion is a technology with the potential of drastically reducing the amount of CO2 emission, it relies on the use of oxygen and recycled CO2 instead of air as the oxidant. This helps to reduce the amount of the CO2 and NOx emissions. This study focuses on the components of flue gas produced and their amounts for oxy-fuel combustion in a coal-fired power plant (CFPP) and also the boiler efficiency using the direct (input-output) method. The combustion process of pulverized coal in a 120MW power plant is studied using Aspen Plus 11. The amount of each component in flue gas in coal-fired processes with air or O2/ CO2 (using recycle of 20%, 40%, 60% and 80% of CO2) as oxidizer was obtained. From the process simulation, as the recycle % of CO2 was increased, the flame temperature, CO and NOx emissions were reduced. The simulation results of air combustion were compared with that of oxy-fuel combustion with 80% recycle and it was seen that the flame temperature dropped from 1894oC when air was used as oxidizer to 1679oC for oxy-fuel combustion with 80% recycle. Also, there was a reduction in the amount of NOx produced, but the SOx levels were constant for both combustion processes. The Gross Calorific Value (GCV) of the coal was calculated from its Proximate Analysis using Dulong’s formula and it was used to estimate the Boiler Efficiency using the Direct (Input-Output) method and a value of 83.6% was obtained.

Dryer design parameters and parts specifications for an industrial scale bagasse drying system

The sugar industry is an ideal sector for electricity cogeneration due to a large amount of burnable bagasse produce as a by-product. Bagasse produced in the sugar industry always consists of moisture affecting the efficiency of a boiler in the cogeneration plant. In our case study, a cogeneration plant run by bagasse burning found with bagasse moisture problem and suffocating with low power generation for the last few years. The boiler efficiency per tonne of bagasse is currently lower than optimal due to the substantial percentage of water present in the bagasse. A bagasse dryer design for this industry can improve the efficiency of a boiler as well as the cogeneration plant. In this paper, a pneumatic bagasse drying system is proposed to reduce the moisture content of bagasse from 48% to 30%. This work provides a full analysis of bagasse dryer design parameters, including specifications for dryer system components, such as feeders, fan, drying tube, and cyclone. The total bagasse drying system proposed is expected to be fitted within a 6 × 6 × 25 m space to dry 60 tph of bagasse, reducing the moisture content from 48% to 30%, in full compliance with all relevant Australian and company standards.

Performance and boiler efficiency using low-grade coal on 400 MWe coal-fired power plant: case study of Suralaya Power Plant Unit 2

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.

A review of the different boiler efficiency calculation and modeling methodologies

A review of the different mathematical methodologies for calculating energy efficiency in boilers was carried out in this work, considering both the methods included in standards and the proposals and applications published in research works. The classification was delimited in analytical methods, mechanistic modeling, and empirical modeling; moreover, the main equations for each of the methodologies are presented, which allows building a compilation that is expected to be useful for a first approach to the subject. It is displayed that those mechanistic models are used to evaluate subsystems or specific cases that require a high level of detail, while analytical models are used to make a first approximation to the systems described, and empirical models stand out in terms of their use at the industrial level if there is access to a starting database to adjust them.

THERMAL LOSSES EVALUATION IN 660 MW COAL-FIRED POWER PLANT USING INDIRECT EFFICIENCY METHOD

Boilers are one of the main equipment in the PLTU apart from turbines and generators. Each year there must be a difference in the actual boiler efficiency value with the conditions during commissioning. Periodically, boiler performance evaluations are carried out in order to identify losses from several factors. In this study, the method used for evaluation is the energy balance method. During the experiment, the standard test guide (ASME PTC - 4) was used. The boiler under test has a capacity of 660 MW. Evaluation is done by comparing the boiler efficiency value at the time of commissioning with the latest performance tests. From the results of performance testing, it is known that the decrease in boiler efficiency when compared with the commissioning results from 86.92% to 82.625%. The reduction in boiler efficiency is due to an increase in heat loss due to dry gas, hydrogen content in coal, and incomplete combustion.Keywords: boiler, efficiency, evaluation, reduction, performance

Fuzzy modelling of combustion efficiency and control of excess air flow case study: 320-MW steam unit/Isfahan Power Plant/Iran

One of the most critical factors affecting boiler efficiency and hazardous-gas-emission reduction is the volume of excess air mixed with fuel. A knowledge-based approach is proposed to model the efficiency of a 320-MW natural-gas-fired steam power plant in Isfahan, Iran by applying fuzzy-modelling techniques to control the boiler efficiency. This model is based on fuel and air entering the boiler. First, the fuzzy-model structure is identified by applying the fuzzy rules obtained from an experienced human operator. The proposed method is then optimized using a genetic algorithm to increase the fuzzy-model accuracy. The results indicate that, by applying a genetic algorithm, the precision of the proposed fuzzy model increases. The error between the actual efficiency of the plant and the output efficiency of the proposed model is low. This model is developed by applying the fuzzy rules and modelling-related calculations. Finally, to optimize the efficiency of the boiler, a fuzzy proportional-integral controller is designed. The closed-loop control simulations are run by applying both the proposed controller and the manual controller to demonstrate the influence of the suggested method. The simulation outcomes indicate that the recommended controller adjusts the excess-air percentage correctly and increases the unit efficiency by 0.70%, significantly reducing fuel consumption.

Co-Combustion of Biomass with Coal in Grate Water Boilers at Low Load Boiler Operation

Environmental protection, and in particular air protection against pollution, is an extremely important element of the global policy of many countries. The problem of air pollution is particularly important in Poland, where the heating market is one of the largest in Europe and is based in 74% on the use of fossil fuels, in particular hard coal. One of the technological solutions for the implementation of cleaner fuels is the co-combustion of coal and biomass. This process enables the reduction of harmful pollutants such as CO2, SO2, and can be implemented in existing boilers. Heating boilers achieve the highest design efficiency during optimal load at the level of 85–95% of nominal power. Under such conditions, heat production is most efficient. During operation, boilers are often started, extinguished or run below rated output, resulting in increased emissions. This publication presents the results of measurements of efficiency and concentrations of pollutants in the WR water boiler during operation below the technical minimum. Hard coal was cofired in the boiler with biomass of wood origin. It was noted that the amount of biomass had a significant impact on the boiler efficiency and pollutant emission. Based on the research, it was also noted that it was possible to make a qualitative prediction of these parameters. The obtained results are an introduction to a deeper analysis and further research on the correlation between the amount of biomass and boiler power and the efficiency and concentration of pollutants.

PERFORMANCE ANALYSIS AND EFFICIENCY IMPROVEMENT OF BOILERA REVIEW

The main objective of this paper is to find out the boiler efficiency calculation and method to improvement. The thermal industry is known as a major source of conventional energy in India. In the thermal power plant where chemical energy of the coal is converted into electricity. It is most demanding industry now days because of high energy demand. Boiler is the most important part for plant. Running the plant with maximum result we need high boiler efficiency. Calculating boiler efficiency as one of the most important types of performance measurement in any power plant. For calculation of Boiler efficiency basically we use Direct and Indirect method. It is a measure of how effectively chemical energy in fuel is converted into heat energy in steam going to the turbine. Finding boiler efficiency from this method from this method use for boiler efficiency, the data is collected from different department in plant like, Boiler Efficiency Department. Many researchers are find out the boiler efficiency of different plant and carried out their research for improvement of boiler efficiency. This review paper helpful to calculate the boiler efficiency and find out the different types of losses occurs in boiler. We also find that boiler efficiency is always somehow increase by implementing this method and useful for further research.

Fuel Used Analysis on Boiler Efficiency Variations and Water Intake Temperature Affected by Palm Oil Varieties

Several factors that affect the use of fuel in boilers are combustion efficiency, quality of feed water management, calorific value, and the potential for available fuel from oil palm varieties. The purpose of this research is to identify the use of fuel and its potential savings based on variations in boiler efficiency and water temperature that entered the boiler. The materials used in this research are FFB mass balance data and boiler fuel composition. Based on the analysis results, the lowest used fuel mass and the highest fuel savings are found in the DxPLangkat variety with an intake water temperature of 105o C and 80% boiler efficiency. The use of fuel is 4,231 kg/hour with shell savings of 967 kg/hour with a value of IDR 725,701. Fiber savings was 487 kg/hour with a value of IDR 121,751.The highest used fuel mass and the lowest fuel savings were found in the Yangambi derivative variety with an intake water temperature of 85o C and 60% boiler efficiency.The fuel consumption is 5,830 kg/hour with shell savings totalling -380 kg/hour. There is no fiber analysis because it is used up hence additional fuel is needed. Additional fuel can be done by asking for other palm oil mill units or buying. If they buy a shell with a requirement of 380 kg/hour, the funds required are IDR 284,939.