Coal-fired Power Generation Plant Research Articles

Selection of an Appropriate Particulate Matter (PM) Separation Device for a Proposed Waste Incineration Plant

Purpose: Waste incineration facilities are the most widely used Waste to Energy (WtE) technology employed in developed economies in the disposal and management of Municipal Solid Waste (MSW). A major drawback of waste incineration facilities is the enormous volume of toxic emissions emitted from these facilities. Particulate Matter (PM) is a complex combination of either solid or liquid particulates produced from the combustion of MSW that are suspended in the air. These particles which are carcinogenic are therefore required to be separated from the emissions from the waste incineration plants prior to its emission into the atmosphere. Materials and Methods: The cyclone, fabric filter, and Electrostatic Precipitators are typical PM separation devices that are employed in conventional coal-fired power generation plants. The adoption of these devices in waste incineration plants therefore require studies to select an appropriate one for use. In this study various models of the waste incineration plants were simulated using the Aspen Plus software aim at selecting an appropriate PM separation device for use in a proposed waste incineration plant in Ghana. Findings: The study concluded that the fabric filter and the ESP are the optimum PM separation devices, achieving an overall separation efficiency of 99.54% and 99.45 % respectively for all particle sizes. The fabric filter was therefore, adopted for use in the proposed waste incineration plant. Implications to Theory, Practice and Policy: It is recommended, however, that a techno-economic analysis is performed on the use of the fabric filter and ESP in the proposed waste incineration facility.

Ultrasonic measurement of temperature distributions in extreme environments: Electrical power plants testing in utility-scale steam generators

Ultrasonic measurement of temperature distributions in extreme environments: Electrical power plants testing in utility-scale steam generators

Technical-economic-environmental analysis of biomass direct and indirect co-firing in pulverized coal boiler in China

Technical-economic-environmental analysis of biomass direct and indirect co-firing in pulverized coal boiler in China

Sustainability assessment of the oxy-combustion coal-fired power plant using low-grade fuel

Sustainability assessment of the oxy-combustion coal-fired power plant using low-grade fuel

NO2 emissions from oil refineries in the Mississippi Delta

NO2 emissions from oil refineries in the Mississippi Delta

A baseline characterization of fine particulate matter (PM2.5) concentration and releases in Nova Scotia, Canada

A baseline characterization of fine particulate matter (PM2.5) concentration and releases in Nova Scotia, Canada

Mechanochemical Characterisation of Calcined Impure Kaolinitic Clay as a Composite Binder in Cementitious Mortars

The availability of some supplementary cementitious materials, especially fly ash, is of imminent concern in Europe due to the projected closure of several coal-fired power generation plants. Pure kaolinitic clays, which arguably have the potential to replace fly ash, are also scarce and expensive due to their use in other industrial applications. This paper examines the potential utilisation of low-grade kaolinitic clays for construction purposes. The clay sample was heat-treated at a temperature of 800 °C and evenly blended with Portland cement in substitutions of 10–30% by weight. The physical, chemical, mineralogical and mechanical characteristics of the blended calcined clay cement were determined. The Frattini test proved the pozzolanic potential of the calcined impure clay, as a plot of its CaO and OH− was found below the lime solubility curve. The 28 days compressive strengths trailed the reference cement by 5.1%, 12.3% and 21.7%, respectively, at all replacement levels. The optimum replacement level between the three blends was found to be 20 wt.%.

Modelling of dew point operating conditions in a rotary regenerative air heater

Dew point related fouling of regenerative rotary air heaters contributes to efficiency reduction of coal-fired boilers. This fouling commonly causes high pressure differences over the air heater steel matrix, along with elevated leakage rates, resulting in increased loading of draught group fans. These increases also conduce to excessive erosion rates, introducing premature failure of element packs and draught group components. The research problem aimed to develop, and validate, a modelling tool to predict the onset of dew point related fouling for regenerative rotary air heaters (VBA RAH model). A modelling tool equip system engineers with the knowledge to enhance operating conditions and maintenance strategies, to prevent the onset of dew point related fouling. The results yielded that the cold end of the air heater packs experience sulphuric acid dew point related fouling for at 670MW(90% MCR), at 544MW(80% MCR) and at 468MW(68% MCR) of the exposure time to the flue gas stream. Different operating and design change configurations were simulated to find potential solutions to minimize dew point related fouling and improving boiler efficiency. The tool provides a platform for identifying methods to reduce maintenance costs and production losses, which will contribute to improved and sustainable operating of coal fired power generation plants.

Cost analysis of environmental protection price of coal-fired plants in China.

In the paper, the achievements obtained from carrying out the policy of environmental protection price for promoting air pollution control in coal-fired power plants in China during more than a decade were summarized. Based on the situation of current electricity market reform, the role and effectiveness of environmental protection price for controlling the normal air pollutants, such as sulfur dioxide, nitrogen oxides, and dust in China's coal-fired power generation plants, were investigated, including the price structure of electricity environmental protection for coal-fired power generation enterprises in different regions, generating units, and power demands. The policy suggestions were proposed, namely, the reform of electricity environmental protection price would be carried out gradually, the relationship between electricity environmental protection price policy and other environmental protection policies would be matched under the relative overcapacity condition, and the environmental protection price regulation would be integrated into other environmental policies.

Sustainable cultivation of Nannochloropsis gaditana microalgae in outdoor raceways using flue gases for a complete 2-year cycle: a Circular Economy challenge

This research was undertaken in the framework of the Circular Economy. Its aim is to assess the technical feasibility and sustainability of a semi-industrial process for the outdoor cultivation of Nannochloropsis gaditana, using flue gases, on demand, from a coal-fired power generation plant. Within this main aim, three secondary objectives were defined: (i) to produce an accurate forecast of the annual average biomass production; (ii) to assess how the production rate and the biochemical composition of the biomass vary with the weather conditions over the course of a year; and (iii) to identify suitable markets for the biomass produced, in accordance with Spanish legislation. The study was carried out over 2 years, and an extra year was taken to analyze the results. The importance of this research is that it covers the lack of current knowledge, based on the available literature, regarding experimentation with microalgae culture outdoors, on a semi-industrial scale of 10,000 L, for a period of two full years. Our results show that, firstly, productivity changes from 0.025 ± 0.010 g (dry weight) L−1 day−1 (g d.wt L−1 day−1) to 0.160 ± 0.030 g d.wt L−1 day−1, as irradiation increases, and secondly, that the content of polyunsaturated fatty acids decreases, from 4.770 ± 0.770% dry weight (% d.wt) to 3.220 ± 0.535% d.wt, as irradiation increases. The maintenance of the culture during a complete cycle of 2 years, under the stated conditions, demonstrates the technical feasibility and sustainability of the process. In accordance with current Spanish regulations, the results of biochemical analysis of the harvested biomass confirm that it is suitable for use as animal feed.

Integrated life cycle assessment of improving saline-sodic soil with flue gas desulfurization gypsum

Integrated life cycle assessment of improving saline-sodic soil with flue gas desulfurization gypsum

Life cycle carbon emission modelling of coal-fired power: Chinese case

Life cycle carbon emission modelling of coal-fired power: Chinese case

Optimization of solar aided coal-fired power plant layouts using multi-criteria assessment

Optimization of solar aided coal-fired power plant layouts using multi-criteria assessment

Water use and demand forecasting model for coal-fired power generation plant in China

China is planning to expand its coal power generation to meet its energy demand and support the economic development. The current level of water use for thermal power generation is 8% of total water use, China is a water-stressed country which is facing many new challenges including climate change and population growth. China’s future coal power industry will add further pressures on already stressed water resources. This raised the key question on how the limited water resources can be managed to meet the demand of planned coal power expansion. A great level of understanding on the present status of water use and forecasting future demand in coal power plant is very important to answer this question. However, knowledge gap, data availability and accessibility are the major challenge in this regard. This paper attempts to improve the knowledge of the water demand in the coal power generation plant in China by using a simple water use model. Furthermore, a method is proposed to forecast future water demand in coal power plant. The proposed method is applied for forecasting water demand in Shaanxi coal power bases in Northern China under four scenarios. The results showed that the future water demand for Shaanxi coal power base will increase by 102–161% compared to current use under different scenarios in order to increase the production capacity by 206%. Adopting the optimum level of current status of water use, it is possible to limit the increase in water demand by 102% or 47.119 million-m3. It is expected that the finding of the study would help decision-making processes in water resources management in Chinese coal power generation.

Effect of carbonization temperature on composition of carbonized woody biomass

Co-firing coal and carbonized woody biomass is an effective method for reducing $$\hbox {CO}_\mathrm{2}$$ emission from coal-fired power generation plants because biomass absorbs $$\hbox {CO}_\mathrm{2}$$ when growing. In this study, we used thermogravimetry along with mass spectrometry and with gas chromatography–mass spectrometry to analyze the effects of carbonization temperature on the composition of carbonized woody biomass prepared from Douglas fir, spruce and pine feedstocks. The obtained carbonized biomass contained both holocellulose and lignin when the feedstocks were carbonized below $$400\,^\circ \hbox {C}$$ and contained mainly lignin when the feedstocks were carbonized above $$400\,^\circ \hbox {C}$$ , because almost all the holocellulose in the biomass feedstocks decomposed at around $$400\,^\circ \hbox {C}$$ .

Internal curing effect of high volume furnace bottom ash (FBA) incorporation on lightweight aggregate concrete

Furnace Bottom Ash (FBA) is a by-product of coal-fired power generation plants. Few studies have focused on assessing the impact of using high volumes of FBA on lightweight aggregate concrete, especially on its dimensional stability and thermal insulation properties. In this study, normal weight coarse aggregate concrete (NAC) and lightweight coarse aggregate concrete (LWC) have been prepared. High volumes of FBA were used to replace natural fine aggregates to prepare the concrete mixes. Silica fume was used to mitigate the high permeability of concrete induced by porous aggregates incorporation. The compressive strength test results show that high strength LWC can be prepared with high volume FBA incorporation. The dimensional stability evaluation shows the linear relationship between FBA replacement ratio and autogenous shrinkage reduction. The internal curing effect of FBA aggregate has been investigated. The increased use of FBA in both NAC and LWC resulted in improved thermal insulation properties. The results indicate the potential of producing high performance lightweight aggregate concrete with high volume industrial by-products.

Performance analysis of a solar-aided power generation (SAPG) plant using specific consumption theory

In contrast to a traditional coal-fired power generation plant where steam extracted from a turbine is used to preheat the feedwater in all preheating stages, a solar-aided power generation (SAPG) plant uses solar heat to replace a part or all of the extracted steam in one or more preheating stages. The performance of an SAPG plant with different replacements is investigated in this study by using specific consumption theory (SCT). Fuel-specific and cost-specific consumption models for SAPG plants are built based on the SCT. A typical 330 MW coal-fired power plant is used as the study case. The performance of the SAPG plant in terms of specific consumption, with steam obtained from the first through the eighth (except for the fourth) stages of extraction replaced by solar heat, is compared with that of the reference coal-fired power plant. The fuel-specific consumption of the SAPG plant is determined to be lower than that of the reference coal-fired power plant. The fuel-specific consumption accrual distribution in SAPG plants is used to assess the effect of each individual replacement. Effective strategies to reduce the specific costs of the SAPG and coal-fired power plants are proposed based on the results of this study.

Environmental and economic assessment of municipal sewage sludge management – a case study in Beijing, China

A case study was conducted in Beijing to identify municipal sewage sludge (SS) management systems appropriate for a sound material-cycle society. The environmental and economic impacts of four realistic SS-handling scenarios were investigated: stabilization by thermal drying, increased inclusion of SS in cement manufacture, and using either dried or carbonized SS as substitute fuel for coal-fired power generation plants. The results showed that the current sludge management system had the lowest operating cost but higher greenhouse gas (GHG) emissions and a low recycling rate. The case with the use of carbonized SS reused in coal-fired power plants had higher energy consumption and almost the same GHG emissions as the current system. On the other hand, the case including more SS in cement manufacture had the same level of energy consumption with much lower GHG emissions. The case with the use of dried SS in coal-fired power plants also resulted in lower energy consumption and lower GHG emissions than at present. Furthermore, sensitivity analysis showed that drying SS with surplus heat from cement plants used less energy and emitted less GHG compared to the other two drying methods.

Direct Nyquist array design of PID controllers for boiler-turbine units based on gain and phase margins

In this paper, a direct Nyquist array (DNA) method for the design of PID controllers for multivariable boiler-turbine units with specifications of gain and phase margins is proposed. The essential objective is to propose a method for the design and auto-tuning of both straightforward and robust PID controllers that can be more easily implemented for the boiler-turbine units in coal-fired power generation plants in the same framework. For this purpose, the model of the original multi-input multi-output (MIMO) system is first converted into a diagonal/diagonal dominance matrix after the system is appropriately compensated. Then, various PID controller design methods for single-input single-output (SISO) systems can be easily extended to decoupled or quasi-decoupled MIMO systems. In particular, the proposed method allows the user to specify the robustness and other key performances of the system through the gain and phase margins specifications. Illustrative example is given to show the design procedure and to compare our method with other existing tuning rules.

Numerical Prediction of Unsteady Flows through Whole Nozzle-Rotor Cascade Channels with Partial Admission

Abstract This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted. Keywords: Numerical Study, Steam Turbine, Unsteady Flow, Partial Admission, Nozzle-rotor Cascade Channels 1. Introduction Steam turbines are used in most of the thermal power plants and the nuclear power plants. The improvement of the steam-turbine performance certainly results in the reduction of the greenhouse gas. Large-scale steam turbines with a nozzle governing system have separated nozzle-blade groups (usually four groups with inlet control valves respectively) for the high pressure first stage (admission stage). For the design condition, valves of the three groups are almost fully opened and one valve of the remaining nozzle group is nearly closed to control the mass flow rate of the turbine system. Also super-critical pressure steam turbines, which were introduced into a number of current coal-fired power generation plants, require a high stiffness design for their admission stage nozzles (nozzle box structure). In these nozzles, some nozzle-blade spacings especially near the horizontal joint flanges are blocked to reinforce their structural stiffness against high pressure and high temperature steam conditions. In these admission stages, since the nozzle-blade spacings are partially opened, the flows into the rotor cascade channels are fluctuated in the circumstantial direction. Generally, internal flows through this kind of partially-opened admission stages cause the loss of the performance. It is also known that this structure causes unsteady and disturbed flows affecting the following rotor blades. The rotor cascade channels occasionally lose flows due to the blocking of the flow at the flange and it results in a relatively lower performance at the admission stage. This loss is called the partial admission loss. Although the prediction of the loss is important, the experimental studies are hard to conduct because of the difficulty of the measurement in actual steam conditions. Therefore, the numerical prediction is quite valuable. But it is suggested that the whole flow fields including nozzles, rotors, and the blocks of the flange and the closed nozzle group should be calculated simultaneously to predict the actual performance. Only a few numerical studies for this flow problem have been reported, because they also require a large-scale computation. A performance prediction for a partial admission has been presented by Cho[1]. He [2] and Sakai [3] have reported the numerical studies solving the quasi three-dimensional Navier-Stokes equations and compared with the experimental r esults. However, no massive computations such assuming whole noz zle-rotor cascade channels have been reported yet. Recently our research group has developed computational codes for unsteady flows of wet-steam through 2-D and 3-D multi-stage cascade channels in a steam turbine using the high-order high-resolution finite-difference method [4][5]. In this paper, the 2-D code is applied to unsteady flows in whole nozzle-rotor cascade channels of a partial admission stage. As numerical examples, the unsteady 2-D flows with a partial admission stage in a middle class coal-fired steam turbine are calculated assuming 108 nozzle passages with two blockages and 60 rotor passages. The effect of the blockage to the unsteady force of rotors is numerically predicted. The performance affected by the change of the number of blockages and the number of nozzles is also parametrically predicted.