of CC, loop-seals and EHEs is higher than ambient pressure. For this reason air ingress is neglected for these components. The construction of the CHE path should be gas-tight, so no air ingress is considered here as well. The only air ingress assumed for CFBC is set at the ESP. Depending on manufacturer's data low air ingress can be guaranteed for such an ESP. In this case air ingress of about 0.5 %, related to the volume flow under standard conditions, is considered at the ESP representing air ingress for the whole fluegas train operated below ambient pressure. In contrast to PC-fired steam generators, where an additional air ingress has to be considered for the gap between burner and furnace or for burner cooling , the lower potential for air ingress seems to be an advantage for an Oxyfuel process with CFBC. All chosen assumptions are in agreement with data from manufacturing and supplying companies. The most important assumptions for the considered Oxyfuel process with CFBC are summarised in Table 1.
boiler exergy efficiency. A. Babu et al.  in a research project identified the sulphuric acid corrrosion as the root cause of failure of utility boiler economiser tubes. They also determined the exergy efficiency of economiser, superheater, combustor and entire boiler as well. Ankit Patel  in an energy and exergy of a boiler with different grades of coal found that major inefficiencies are due to the heat transfer and combustion processes. Mukesh Gupta and Raj Kumar  analyze the effect of hot air temperature on the thermoeconomic performance of a boiler used in a coalfired thermal powerplant and optimize the boiler as a trade off between the unit product cost of hot air and unit product cost of the boiler system. M. Bakhshes and A. Vosough  in a study found that the decrease in stack gas temperature and excess air quantity improves the performance of a powerplant with a gasfired steam generator. L. Pattanayak  in a steady state energy and exergy analysis of pulverized coalfired boiler using Ebsilon software for component wise modeling and simulation found that maximum exergy destruction occurs at combustor followed by heat exchanger. T. Ashok Kumar et al.  carried out the exergy analysis of a coal based 63MW circulating fluidized bed boiler and found that the boiler system utilises 88.41% of the total energy supplied to the plant and nearly 6.7% of heat supplied is carried away by the exhaust gas. Ameet P. Koringa and N. S. Mehta  in a mathematical analysis of boiler by using first and second law of thermodynamics determined the boiler energy and exergy efficiencies as 71.6% and 25% respectively. M. Siddharth Bhatt and S. Jothibasu  in a syudy for performance enhancement in coalfired thermal power plants with specific reference to the boilers evaluated the efficiencies and performance indices of the equipment. They investigated the generic problems associated with design, operation and fuel inputs and suggested some appropriate solutions. Jun-Ta WU  in a research work on the optimization of boiler efficiency based on Artificial Bee Colony (ABC) algorithm found that the optimal value of parameters for optimization of boiler efficiency can quickly be obtained by the algorithm. S. S. L. Patel and G. K. Agrawal  in an assessment of boiler losses and investigation of influencing parameters found the dry flue gases as the biggest source followed by the loss due to hydrogen in fuel.
None of the above-mentioned literature has reported the impact of biomass on power plants integrated with a carbon capture technology. A techno-economic assessment of a standalone biomass firedpowerplant with two different kinds of CCS technologies, including PCC and oxy-fuel system, have compared the cost and emissions incentives to that of a coalfiredpowerplant using IECM (Al-Qayim et al., 2015). IEA (2009) reported different case studies for the co-firing of biomass with coal for different technologies, including pulverised fuel firing, circulatingfluidisedbed firing and bubbling fluidisedbed firing. Similarly, the same results as that of the IEA (2009) have been reported in (Domenichini et al., 2011). Benchmarking comparison of NGCC, coal and biomass firedpower plants integrated with a MEA-based CO 2
There are five major parameters that influence collected ash composition in coal-firedpowerplant waste products. Ruud Meij and Henk te Winkel (2007) identified the five primary parameters and secondary parameters of influencing factors. For the first primary parameter of fuel, the secondary parameters are type and origin of coal, ash content of coal, the stages of peat, industrial and domestic waste, etc. The secondary parameters of the combustion technique are grate boilers, pulverized coal boilers with dry ash removal, pulverized coal boilers with wet ash removal, cyclone boilers, gasification, fluidized bedcombustion, fluidized bed gasification, etc. The third primary parameter is temperature and period of residence, with the secondary parameters being during combustion and in the fluegas. The fourth is the type of particle filter, with the secondary parameters of ESPs (high-temperature, low temperature, dry and wet systems), cyclones, baghouses, wet systems, and filter efficiency. The last primary parameter is other fluegas clean-up systems with secondary parameters of deNOx, carbon injection, etc. Among the above parameters, the parameters that have the greater impact on the heavy metal concentration in coal-firedpowerplant products is the type and origin of coal and the stage of peat, while the other parameters have supplementary effects. Thus, there is a direct relationship between the concentration of heavy metals in atmospheric powerplant ash emissions and heavy metal content in raw coal.
Spare parts inventory of a powerplant typically accounts for more than 5% of the operating cost. An excess of spare parts will leads to a high holding cost and it slow down the cash flows, whereas insufficient spare parts result in costly production delays and causing a negative impact on the plant performance. Different companies will need a different type and number of spare parts. Spare parts inventories are different from other types of inventories in companies, Cohen et al (1990). Rego et al (2006) have pointed out several important factors on the spare management for the inventories:
In AFBC, coal is meshed to a size of 1 – 10 mm depends upon the recycled quality of coal, type of fuel feed and fed into the combustion chamber. In this atmospheric air use as fluidization air and combustion air which delivered at a pressure which preheated by the discharge flue gases and pass through the bed. The velocity of fluidising air is in the range of 1.2 to 3.7 m /sec. The velocity of air which is blown through the bed decides the quantity of fuel that can be reached. Almost all AFBC/ bubbling bed boilers use evaporator tubes in the bed of sand, limestone and fuel for removing the heat from the bed to maintain the bed temperature. The depth of bed is generally 0.9 m to 1.5 m deep and the pressure fall averages around 1 inch of water per inch of bed depth. Around 2 to 4 kg of solids of material leaving bubbling bed is reused per ton of fuel burned. The main advantage of atmospheric fluidisedbedcombustion is working of within the relatively narrow temperature range. With coal, there is risk of clinker development in the bed if the temperature exceeds 950°C and loss of combustion efficiency if the temperature falls below 800°C. For efficient sulphur retention, the temperature should be in the range of 800°C to 850°C .
23 In big utility plant such as the one illustrated in Figure 3.3, detailed observation on each of its operational parameters is crucial. According to , it is important to acquire real data from an actual working boiler unit in order to be able to identify possible scenario for the simulated fault detection system to be trained and provide feedback accordingly. Identifying faults and trip condition of a boiler in its most effective operating condition requires in depth understanding and knowledge of its faulty parameters and factors causing the malfunctions. Since there are a large number of data obtained from the industry, irrelevant values and outliers need to be identified and removed. The parameter selection is based on plant operator’s experience on identifying the essential variables that contributed to the boiler trips of the particular unit. The boiler operational parameters identified for this study are listed in Table 3.1. The design of the steam cycle and its operating condition involving the steam supply and discharge condition; dictates the pressure, temperature and flow rate of the steam required to generate the specified power output . In order to achieve this requirement, steam is directed through a piping system to the turbine as the point of use. Throughout the steam circulating system, the steam pressure is regulated using valves and checked with steam pressure gauges . Parameters monitored for ideal condition of the steam cycle are listed in Table 3.2.
the sweep gas. Secondly, the solid residence time in practical adsor- ber and desorber reactors is much shorter than the time taken to reach the equilibrium condition. Therefore breakthrough capacity should be used as the working capacity. Finally, the circulating solid adsorbent particles are most likely partially degraded after many cycles even with a constant replacement rate. Based on the above considerations, the working capacities in this study are adopted as 6 wt% for the PC case and 5 wt% for the NGCC case, which are both substantially lower than the equilibrium capacities demonstrated on previous TGA and cyclic batch-type ﬂuidized bed tests (Zhang et al., 2014b). The moisture adsorption of 2wt% was experimentally determined for the PEI/silica adsorbent in a modiﬁed TGA system which can generate a certain level of moisture with the carrier gas. The adsorption capacity of the moisture was obtained in the pre- saturation test of moisture followed by the co-adsorption of both CO 2 and moisture at the adsorption temperature of 70 ◦ C. Details
Initially, the fundamental concepts of the boiler and its auxiliaries were studied to lay the foundations of the coal, air and fluegas systems in a coal-fired boiler plant. From literature survey emerged that coal consumption is defined as a critical indicator of plant performance in terms of cost and efficiency. The different methods used for flow measurements (coal, air and fluegas) in a coal-fired boiler plant, MEB and CFD were further reviewed. The MEB method was used to determine coal, air, and fluegas mass flow rates and the plant’s heat rate. Furthermore, CFD was used for air flow visualization and optimization in the secondary air system. The air flow in the secondary ducting system (extracted from the 3D plant layout) was simulated with CFD, using ANSYS Fluent. This was done in order to visualize the velocity of the air flow in each section of the ducting system and at burners’ exits. As part of the simulation process, the type of mesh used was tetrahedral, and the simulation calculation was done using a continuity, momentum and energy equations solver. The simulation process was done gradually using coarse, medium and fine mesh sizes with respect to the boundaries of the secondary air duct, which has an inlet located at the air heater’s exit and 18 outlets, each supplying 18 burners.
Thus, to recover the surplus pressure of the extracted steam, a new letdown steam turbine generator (LSTG) is installed to recover the surplus energy of the extracted steam in the new decarburized system, as shown in Fig- ure 4. Such improvement is really simple and easy to implement while it is very effective to retrieve the sur- plus pressure and temperature, which can also make the output power greatly increase to a certain degree.
biomass combustion but with further tightening emission limits it will increase its market share. The biggest advantage with FF is the very high removal efficiency almost independently of the particle size and distribution. Thus, it is normally possible to design a fabric filter for a dust emission of less than 10 mg/m³. A fabric filter must operate with rather dry dust otherwise it cannot be removed from the fabric. On the other hand, it can tolerate a certain amount of droplets but the ratio of droplets to dry dust must be controlled. A fabric filter shall normally be designed so that a dust cake can be formed on the fabric. This dust cake will then work as a filter media and in this dust cake droplets can be removed. Droplets and sticky dust must be prevented from penetrating into the fabric.
reaction stage speed of carbonation process, but it has little effect on the final conversion rate; water vapor can increase the final conversion rate of carbonation; the cycle times will reduce the activity of carbonation. The presence of car- bonation turns the traditional boiler fluegas indirect desulfurization model into indirect desulfurization mechanism which does not have a negative impact on SO 2 removal efficiency.
With regards to solid waste, ash dumps have been found to contribute to air pollution, particular- ly in the form a particulate matter (PM) when fly ash from ash dumps is carried into the atmosphere by the wind. Sludge and slurry pools have also been linked to ground water contamination, which has a variety of health and environmental consequences (Epstein et al., 2011). With this in mind, coal-firedpower plants are a major contributor to atmospher- ic pollution levels. Multiple local and international studies have sought to quantify the socio-economic and environmental damages associated with pollu- tants from coal-fired electricity generation. We add to this literature, through the examination of the potential health effects that could arise from one new coal-firedpower generation plant – Kusile, specifically, the localised health impacts and costs associated with these impacts. The analysis is based upon the Impact Pathway Approach (IPA).
Technological approach as a mitigation alternative is an approach which employs a method or technology in the form of program / project to manage large and important impact. The scope of the technology being considered is the technology that is available, either already known and used, as well as those brought in from the outside and ready to use so it does not have to affect the operational schedule or implementation of powerplant construction.
ABSTRACT: Main essence for the thermal power plants that may be either coal or natural gaspower plants to be in command of the temperature and pressure controllers (PI.PD, PID) is generally employed. The raw material, coal is nosh in to the boiler using conveyer system and it is a time shifting one. This coordinated boiler turbine system, multivariable complex process, nonlinear and also slowly time variant plant with hefty settling time. This is due to the unpredictable demand in the load side Also it makes the PI.PD, PID controllers to have very a reduced amount of efficiency. To make it as a high efficient one, the FUZZY LOGIC is used to control and it is a self and auto tuning process. The control of boiler temperature and pressure is done by FUZZY logic controller without the human intervension. Sensor materials like Temperature sensor (LM235) and pressure sensor (POTENTIOMETRIC TYPE) are used to sense the temperature and pressure. When the normal level of temperature and pressure value exceeds, it will give the signal to FUZZY controller. Then fuzzy logic controller that is used to control is worn the boiler system by given value to it by using its membership functions values. Since FUZZY logic controller is used, controlling sped is possible at any time Multivariable, nonlinearity and time varying and time varying of the unadventurous coal conveyor system can be easily eliminated. Unremitting controlling is applied by relay unit. Effectiveness is high compare with existing technology. Low temperature and pressure values can be set up in this strategy of FUZZY logic controller comparing with the conventional controller approach.
The power sector needs to be decarbonised by 2050 to meet the global target for greenhouse gas emission reduction and prevent climate change. With fossil fuels expected to play a vital role in the future energy portfolio and high efficiency penalties related to mature CO 2 capture technologies, this research aimed at evaluating the efficiency improvements and alternate operating modes of the coal-firedpower plants (CFPP) retrofitted with post-combustion CO 2 capture. To meet this aim, process models of the CFPPs, chilled ammonia process (CAP) and calcium looping (CaL) were developed in Aspen Plus ® and benchmarked against data available in the literature. Also, the process model of chemical solvent scrubbing using monoethanolamine (MEA) was adapted from previous studies. Base-load analysis of the 580 MW el CFPP retrofits revealed that if novel CAP retrofit configurations were employed, in which a new auxiliary steam turbine was coupled with the boiler feedwater pump for extracted steam pressure control, the net efficiency penalty was 8.7–8.8% points. This was close to the 9.5% points in the MEA retrofit scenario. Conversely, CaL retrofit resulted in a net efficiency penalty of 6.7–7.9% points, depending on the fuel used in the calciner. Importantly, when the optimised supercritical CO 2 cycle was used instead of the steam cycle for heat recovery, this figure was reduced to 5.8% points. Considering part-load operation of the 660 MW el CFPP and uncertainty in the process model inputs, the most probable net efficiency penalties of the CaL and MEA retrofits were 9.5% and 11.5% points, respectively. Importantly, in the CaL retrofit scenarios, the net power output was found to be around 40% higher than that of the CFPP without CO 2 capture and double than that for the MEA retrofit scenario. Such performance of the CaL retrofit scenario led to higher profit than that of the 660 MW el CFPP without CO 2 capture, especially if its inherent energy storage capability was utilised. Hence, this study revealed that CaL has the potential to significantly reduce the efficiency and economic penalties associated with mature CO 2 capture technologies.
As a step toward addressing these questions, Congress may consider chartering a rigorous study of the potential for displacing coal with power from existing gas-firedpower plants. Such a study would require sophisticated computer modeling to simulate the operation of the power system, to determine whether there is sufficient excess gasfired capacity and the supporting transmission and other infrastructure to displace a significant volume of coal over the near term. This kind of study might also estimate the direct costs of a gas for coal policy, such as the impact on electric rates. Because of the large number of uncertainties, such as the future price of natural gas, the study would have to consider several scenarios. Such a study could help Congress judge whether there is sufficient potential to further explore a policy of replacing coal generation with increased output from existing gas-fired plants.