Boiler Output Research Articles

Analysis of Exhaust Gas Heat Utilization in Waste Heat Recovery Power Generator at Indarung V Factory PT Semen Padang

Increasing energy efficiency in the cement production process at PT Semen Padang is carried out by reusing exhaust gas to produce electricity using Waste heat recovery power generation (WHRPG) with a capacity of 8.5 MW. WHRPG is a technology for utilizing exhaust gas heat as a source of heat energy to heat feed water into steam by using a suspension preheater (SP) boiler and air quenching cooler (AQC) boiler. This study aims to calculate the power potential of the steam heat influenced by the steam temperature and the mass flow rate of the steam produced by the boiler, to calculate the efficiency of the boiler using the direct method by comparing the boiler output heat against the boiler input heat, to calculate the turbine efficiency based on the difference between the steam enthalpy enter the turbine against the steam enthalpy out of the turbine and the isotropic enthalpy of the steam out of the turbine and to calculate the power generated by WHRPG at PT Semen Padang. The results obtained in this study are the total potential power of steam heat is 19.778 MW, the boiler AQC efficiency is 70.30%, the boiler SP efficiency is 94.04% and the turbine efficiency is 78.64%. The electricity generated by PT Semen Padang's WHRPG is 3.70 MW.

Four approaches for the year-round operation of wood-fired heating plants with low pollutant emissions

Fluctuations in heat demand and low heat demand in summer make it difficult to operate wood boilers all year round at high efficiency and low pollutant emissions. Therefore, today's wood-fired heating plants are often equipped with an auxiliary fossil fuel boiler. This paper investigates technical approaches to operate wood heating plants without additional fossil heat while avoiding unfavorable operation with high pollutant emissions. To evaluate these concepts, the dynamic behavior of wood-fired heating plants is modelled. The model includes one to four wood boilers, an auxiliary fossil fuel boiler, the heat demand, a stratified heat storage tank and the control system. The simulation reveals that the fossil share can be eliminated by large boiler output ranges and the use of several wood boilers in cascade. High storage capacities and large boiler output ranges enable low pollutant emissions and low cool down losses of the wood boilers. By doubling the storage capacity from 30 to 60 min of the nominal boiler output, reductions of the annual emissions of carbon monoxide and particulate matter of 17% and 8% are observed. Mitigating heat demand peaks can reduce pollutant emissions of heating plants with small storage capacity.

Performance Analysis of a 300 MW Coal-Fired Power Unit during the Transient Processes for Peak Shaving

A simulation model based on Dymola modelling was developed to investigate the dynamic characteristics of automatic generation control (AGC) for variable-load thermal power units in this study. Specifically, a 300 MW unit from a power plant in northern China was used to verify the model’s validity in steady-state processes and to analyze the behavior of the main thermal parameters under different rates of load changes. The economic performance of the unit under different rates of load changes is also analyzed by combining the economic indexes of “two regulations” in the power grid. Results indicate that as the rate of load changes increases, boiler output, main steam temperature, reheat steam temperature, main steam pressure, and working temperatures of various equipment fluctuate more intensely. Specifically, at a rate of load reduction of 2.0% Pe MW/min, the maximum deviation of the main steam temperature can reach 7.6 °C, with the screen-type superheater experiencing the largest heat exchange. To achieve a balance between safety and economics for the unit, the rate of load raising should not exceed 1.2% Pe MW/min, and the rate of load reduction should not exceed 0.8% Pe MW/min. This paper applies the covariance index and AGC assessment index of the thermal power unit load control system to the established dynamic simulation model to supplement the AGC assessment index in the “two regulations”, and to provide a flexible and reasonable system evaluation result for field operators to refer to, so as to improve the economics of the system on the basis of safety.

Comparison of Principal-Component-Analysis-Based Extreme Learning Machine Models for Boiler Output Forecasting

In this paper, a combined approach of Principal Component Analysis (PCA)-based Extreme Learning Machine (ELM) for boiler output forecasting in a thermal power plant is presented. The input used for this prediction model is taken from the boiler unit of the Yermarus Thermal Power Station (YTPS), India. Calculation of the accurate electrical output of a boiler in an operating system requires the knowledge of hundreds of operating parameters. The dimensionality of the input dataset is reduced by applying principal component analysis using IBM@SPSS Software. In the process of principal component analysis, a dataset of 232 parameters is standardized into 16 principal components. The total dataset collected is divided into training and testing datasets. The extreme learning machine is designed for various activation functions and the number of neurons. Sigmoid and hyperbolic tangent activation functions are studied here. Its generalization performance is examined in terms of the Mean Square Error (MSE), Mean Absolute Error (MAE), Root Mean Square (RMSE), and Mean Absolute Percentage Error (MAPE). ELM and PCA–ELM are compared. In both the ELM and PCA–ELM models, when the extreme learning machine was designed with a sigmoid activation function with 100 nodes in the hidden layer, RMSE was 5.026 and 4.730, respectively. Therefore, the developed combined approach of PCA–ELM proved as a promising technique in forecasting with reduced errors and reduced time.

Drying biomass using waste heat from biomass ash by means of heat carrier

Agricultural and forestry biomass direct-fired power generation represents an important technology to promote low-carbon energy transition and sustainable development. To solve the problems of boiler output fluctuation caused by unstable combustion of high moisture content biomass and insufficient recovery of ash waste heat after combustion, steel heat carriers (HC) were used to absorb high-temperature ash (HTA) waste heat, and then HC was directly mixed with high moisture biomass for dewatering and drying. The thermal efficiency of waste heat recovery decreased with the increase of ash temperature, and the highest thermal efficiency of waste heat recovery was 77.4% at a heat-carrying spheres temperature (THC) of 600 °C and a mixing mass ratio of 3. Through the optimization of waste heat recovery and mixed drying process, at a biomass ash temperature of 800°C, 1 kg of ash was able to dry 0.75 kg of high moisture content biomass, resulting in a reduction in fuel moisture by about 10%.

Technical and Economic Evaluation on the Integrated Heating System With Coupled Heat Pump and Backpressure Turbine

Abstract The increasing depletion of fossil energy and the gradual aggravation of environmental pollution have increased the necessity of renewable energy applications. However, the intermittent characteristics of renewable energy power generation need to increase the flexibility of the original coal-fired power unit for balancing the supply and demand of the power system. In this work, two 350 MWe condensing units (CUs) were taken as examples and the thermodynamic simulation models were built by the ebsilon software to evaluate their technical and economic characteristics. At the same time, the system is coupled with heat pump (HP) and backpressure turbine (BT) for heating. Among them, the rated steam intake of HP is 194.9 t/h, and the rated steam intake of BT is 214.5 t/h. Results show that under the same requirements, the energy consumption with the backpressure turbine priority principle (BTtlp principle) is smaller than that with the heat pump priority principle (HPtlp principle). However, under the same thermal load conditions, the electrical load with the HPtlp principle can drop lower than that with the BTtlp principle. Meanwhile, there is an optimization interval for the output distribution of HP and BT. From the energy current diagram, it can be found that under the design main steam and given thermal load condition, the power generation efficiency of coupled mode is 0.74% more than that of HP mode and is 1.93% more than that of direct mode, while under the given thermal and electrical load condition, the system’s boiler output with direct mode is 3.37% more than that with HP mode and is 5.34% more than that with coupled mode. This provides a theoretical basis for the subsequent comprehensive evaluation of heating reformation.

Integrated mathematical modelling of a 105 t/h biomass fired industrial watertube boiler system with varying fuel moisture content

In this paper, a steady-state 1D computer model of a complete sugarcane bagasse-fired boiler system is presented, which pays special attention to the different heat transfer phenomena encountered in the boiler heat exchangers. The model solves the mass, momentum and energy balance equations for water, flue gas and air streams in an integrated manner which utilizes fundamental equations and empirical correlations for pressure drop, radiative heat transfer and convection. The integrated model is successfully applied to model a 105 t/h industrial watertube boiler at three different load cases namely 100 t/h, 65 t/h and 35 t/h. The model results are validated using typical plant measurements. The mean relative predicted gas temperature errors are 1.47%, 0.58% and 4.84% respectively for the different load cases simulated, and for the water circuit temperature predictions the mean errors are 1.48%, 0.85% and 5.31% respectively. Additionally, a sensitivity analysis is performed on the integrated model, which investigates the influence of selected modelling parameters such as flame height on key boiler output variables such as the furnace exit gas temperature.

Influence of boiler output and type on gaseous and particulate emissions from the combustion of coal for residential heating

The study describes gaseous and particulate emissions from the combustion of two types of coal (hard and brown) in three types of boilers (one modern-type and two old-type boilers) used for residential heating. The importance of the heat outputs (nominal and two reduced outputs) for the emission of pollutants was also studied. Three outputs (95–108%, 58–73% and 26–50%) covered the expected operation of these boilers in real households under different outdoor air temperatures in the winter. Gaseous components (NOx, SO2, CO, CO2, OGC) and particulate organic compounds (n-alkanes, polycyclic aromatic hydrocarbons, hopanes) were determined in the emissions. In general, the emission factors (EFs) of the products of incomplete combustion were higher from the combustion of coal in old-type boilers than from that in the modern-type boilers. The EFs of particulate matter varied between 11.6 and 17.0 g kg−1 (hard coal, the oldest-type boiler), and 0.290 and 0.544 g kg−1 (brown coal, the modern-type boiler). The trends between the EFs of particulate organic compounds and the outputs of boilers were observed only with the automatic boiler (modern-type boiler). Similar trends for old-type boilers were not observed, probably due to the high instability of the combustion process as a result of the old construction of these boilers. Diagnostic ratios of the PAHs and the homohopane index, used for source apportionment of particulate matter in ambient air, were calculated. While the calculated homohopane indexes were similar to those reported in the literature, the calculated diagnostic ratios for PAHs related to coal combustion were different.

Обґрунтування рішень технічного переоснащення котлоагрегату Трипільської теплоелектростанції

Здійснено аналіз варіантів, зокрема з урахуванням досвіду технічного переоснащення енергоблоку ст. № 4, виконано передпроектні розрахунки технологічних схем для системи приготування пилу, подачі пилу в котел та спалювання в котлі ТПП-210А блоку ст. № 3 Трипільської ТЕС вугілля марок Г та ДГ з максимальним збереженням компоновки наявного обладнання за різних навантажень, пусків і зупинів, оцінено досяжний діапазон потужності блоку під час роботи на вугіллі марок Г та ДГ та обґрунтовано сукупність технічних рішень для переведення котла ст. № 3 на газове вугілля. Виконано позонний тепловий розрахунок топки за визначеними варіантами за різних навантажень. Проведено розрахункову оцінку діапазону навантаження для забезпечення умов РШВ, запобігання шлакуванню ширм та збереження наявних температурних умов експлуатації стінок НРЧ під час спалювання газового вугілля різної якості. Виконано повіркові теплові розрахунки котла ТПП-210А ст. № 3 згідно з Нормативним методом з використанням довідкових даних для визначення можливості несення котлом номінального та часткових навантажень. Загалом було виконано 9 варіантів розрахунків (на антрациті з калорійністю 5500 ккал/кг на номінальному навантаженні – для верифікації застосованого методу та вихідних даних щодо котла; на двох розрахункових паливах на навантаженнях 100, 90, 80 та 70 % від номінального). Для розрахунку використовували фактичні значення присмоктів у топку, елементи конвективної шахти та РПП. Підтверджено можливість та доцільність реалізації схеми зі скиданням відпрацьованого сушильного агенту до скидних пальників як витратно-швидкісними розрахунками пилосистем і пальників, так і повірковими позонними розрахунками топки для обох видів розрахункового вугілля на навантаженнях від 100 до 70 % від номінального. Показано, що температура газів та питоме теплове навантаження променесприймальної поверхні у всіх зонах топки під час спалювання газового вугілля не перевищують ті, що реалізуються під час спалювання антрациту, що свідчить про непогіршення наявних (як під час спалювання антрациту) температурних умов експлуатації стінок НРЧ під час спалювання газового вугілля у всіх зонах топки.

Greenhouse gas credits from integrated waste-to-energy plant

In Europe, most of the district heat is produced from fossil energy sources such as coal or natural gas. Together with the intention to divert municipal waste from landfill, which is still the main way of treatment in approximately half of the EU countries, there is a potential for the construction of waste-to-energy plants (WtEP) that can partially replace fossil fuels. An important factor in planning the construction of new WtE plants is the assessment of the project’s economy. However, the ecological aspect of the project, namely the greenhouse-gas (GHG) savings, is becoming a topic of discussion nowadays. In terms of GHG savings, WtE plant integration into an existing district heating system (DHS) has a positive impact, but its level is often only roughly estimated. The paper presents a comprehensive mathematical optimization tool working on a daily time interval that is able to evaluate the impact of changing current technology or WtE plant construction on global warming potential. The technical parameters such as boiler output range, energy efficiency, etc. are considered. The tool also allows to put in the context the GHG savings and economic benefits of the project. These two factors are very difficult to compare. The study answers the question of how to deal with this issue and presents the possibility of comparison, which is generally transferable to any two parameters. Due to two poorly comparable criteria, the result does not include a single optimal solution, but clearly illustrates the view of the overall issue and gives a good basis for the final decision. The method used are illustrated in real-world DHS with various parameters where the relationship between GHG savings and the economic benefits of the integration of a WtE plant is evaluated. The whole problem is the task of linear integer programming and is implemented in the GAMS programming environment.

Measurement and calculation of calorific value of raw coal based on artificial neural network analysis method

The calorific value of coal is the basic technical basis for calculating parameters such as boiler heat balance, thermal efficiency, and boiler output. The calorific value of coal has different meanings, such as the calorific value of the cartridge, the high calorific value of coal, and the low calorific value of coal to generate heat at a high level of constant humidity and no ash. This paper focuses on the analysis of the structure and algorithm characteristics of artificial neural network and RBF neural network. On this basis, the predictive modelling of the received low-level calorific value is carried out. Through the test summary, the predictiveness of the neural network is better than the empirical formula. For the prediction problem with small sample size, the RBF network has better prediction performance. In addition, the quality of the sample, including its quantity and comprehensiveness, has an important impact on the predictive performance and generalization ability of the model.

ANALISIS KINERJA BOILER DI PT. PLN (PERSERO) WILAYAH KALIMANTAN SELATAN KALIMANTAN TENGAH SEKTOR PLTU ASAM - ASAM

Boiler is a tool that serves to convert water into pressurized steam. In the heat causes heat boiler heat transfer through the water into pressurized steam that is heated from the fuel in the furnace.And often a problem of burning in the boiler is less than the maximum. Because the incoming energy is energy derived from the fuel, there is some energy lost during the combustion process it happens because the fuel has a low heat so that the combustion is not maximal cause the boiler performance is reduced. To avoid this, it is necessary to maintenance for the boiler component in order to improve performance. Direct method is "input - output method" because this method uses only the heat in the fuel and steam coming from the boiler output. Boiler efficiency of research results from the date of March 27, 2017 until the date of 10 April 2017 with a total average - average efficiency were analyzed, namely 74.4%. On April 3, 2017 the calculated efficiency of 76.57% indicates that the boiler performance is still feasible to operate but on April 4, 2017 the boiler efficiency becomes 71.59%. Boiler efficiency at commissioning, with boiler efficiency of 85.13% and in 2017 done the boiler efficiency calculation theoretically on 27 March until 10 April 2017 with total average 74.4% where the efficiency decrease equal to 10.73%. Factors affecting the efficiency ratio are in the coal content used. Keywords:Boiler, Performance, Direct Method

Failure analysis in a steam turbine stop valve of a thermal power plant

In the current study, the problem of cracking on the stop valve body in a steam turbine related to a thermal power plant is assessed. The problem usually occurs consecutively and almost in identical locations for the power plant's stop valves. To do so, the steam flow path from the developed area at the boiler output to the turbine input is divided into three separate computational domains and numerically simulated. The obtained results of the simulation have been successfully verified using the actual data of the thermal power plant. The common factors affecting the formation of crack consist of contacting shell with cooled steam, expansion and contraction movement of a turbine, insufficient insulation, stop valve spring force, internal pressure, and fluid flow momentum are assessed. The von Mises stresses caused by each factor have been determined. It has been attempted to identify the main cause of cracking by comparing the obtained stress concentration points with the real coordinates of the crack. The results of the simulation revealed that the expansion and contraction movements of the turbine were the main cause of fatigue and crack in the stop valve body. Given the key role of the stop valve in generating power of turbines, the findings of this simulation can help to design sensitive equipment more accurately.

The effect of circulating fluidized bed boiler load on the emission of mercury

The paper deals with the determination of mercury balance for a hard coal-fired circulating fluidized bed boiler operated at various loads (i.e. 100%, 75% and 50% of the Maximum continuous rating, MCR). The research was focused on the determination of the mercury balance by providing data on Hg content in fuel, limestone sorbent, and in the combustion by-products (fly ash and bottom ash). Furthermore, the concentration of mercury in the flue gas in two zones i.e. upstream and downstream the electrostatic precipitator (ESP) were also determined in order to assess the effectiveness of the ESP in mercury reduction. For the calculation of the Hg balance both gaseous mercury species, Hg0, and oxidized mercury, Hg2+, were taken into consideration.The results indicated that over 95% of the mercury was fed into the boiler system with coal and just less than 5% with limestone used for ‘dry’ desulfurization of the flue gas. As for the boiler output, very high mercury content was determined in the fly ashes, while just a minor part (a few percent of the total mercury input) was found in the bottom ashes. The shares of Hg0 and Hg2+ mercury were affected by boiler load.

Thermal energy storage tank sizing for biomass boiler heating systems using process dynamic simulation

A novel methodology for optimizing thermal storage for biomass boiler heating systems is presented in this paper. Biomass boiler heating systems have gradually gained popularity in residential, commercial, and large-scale district heating plants due to the lower carbon footprint of biomass energy. One unanswered question in this field was the size of the thermal energy storage (TES) tank with respect to different boiler capacities and different types of heat demand profiles. Different standards and recommendations (based only on boiler capacities) have been proposed by various organizations around the world with large deviations on the sizing of the TES tank, but without a clear technical basis for these recommendations. These inconsistencies impede the effective design and deployment of biomass boiler heating systems. This study used a dynamic process simulation system based on field data from a 25-kW wood pellet boiler with radiant floor heating. By running the simulation for different boiler capacities (N) and different types of heat demand profiles (i.e. low, medium, high, intermittent, and variable), the optimum TES tank volume can be estimated by evaluating the TES tank discharge efficiency, boiler on-time, boiler off-time, and maximum boiler output temperature. Linear correlations between optimum TES tank volume and boiler nominal capacity for different types of heat demand profiles were obtained. The results showed that the medium building heat demand (45% N) required the smallest TES tank volume while intermittent building demand requires the largest. High building demand (60% N) generates the highest TES tank discharge efficiency (up to 99%) but also requires large storage volume. From the economic point of view, it is recommended to size the thermal energy storage system such that the average building heat demand is around 45% of boiler nominal capacity.

Analysis of heat source selection for residential buildings in rural areas

The research aiming to check whether the output of currently installed boilers matches the use requirements together with estimation of their energy efficiency was carried out on a group of 84 single-family residential buildings located in rural areas. Heating and hot water energy needs were calculated for each building in order to determine the use requirements. This enabled verification whether the currently installed boilers match the actual use requirements in the buildings. Based on the calculations it was determined that the designed average boiler output in the group of buildings subject to analysis is 15.7 kW, whereas the mean rated output capacity of boilers installed therein is 25.4 kW. On average, the output capacity of the installed boilers exceeds the use requirements for the buildings by 60%. To calculate the energy efficiency of boilers, the mean annual boiler output capacity use coefficient was determined. For boilers selected on the basis of standard calculations, the mean coefficient is 0.47. For boilers currently in use it is 0.31, less than the above figure. The above calculations show that if boilers were correctly selected in compliance to the building needs, then the average estimated seasonal efficiency of 65% would be feasible. However, in the current state the achievable efficiency is approx. 55%.

Performance Evaluation of Two 25 kW Residential Wood Pellet Boiler Heating Systems

A significant increase in the use of wood pellets for residential space heating has occurred over the past decade. The performance of two modern residential wood pellet boilers [designated Parishville boiler (PB) and West Potsdam boiler (WPB)] were evaluated, including boiler thermal efficiency, thermal energy storage (TES) tank discharge efficiency, and system efficiency. A correlation applicable to both systems between the boiler thermal efficiency (ηth, %) and the boiler output load (χ, %) was found in the form of ηth = 52.69 ln χ – 137.7, with r2 = 0.79 (for 25 < χ < 75). This equation provides an easy, accurate estimation of the boiler thermal efficiency in field operations. The boiler thermal efficiency decreased with time, and this decline was determined using a Mann–Kendall trend analysis with Sen’s slope. This decrease was primarily the result of fouling in the heat exchanger, and thus, this analysis identifies the need for manual cleaning of the heat exchanger tubes to restore maximal system per...

Levelized cost of energy analysis of co-firing solid, liquid and gaseous fuel

One of the main obstacles to transfer to carbon neutral energy management is technological transition. An important task is to change fuel used in the boiler furnace from natural gas (fossil fuel) to biomass. The easiest but most expensive solution is the installation of a biomass boiler. Other solutions include burner replacement or additional installation, but these options are more complex from an engineering and technical point of view.By replacing natural gas with wood particles, boiler output is reduced, because the value of combustion heat, furnace load and specific combustion parameters are lower, as well as the temperature and pollution with nitrogen oxides NOx decrease. If energy end user improves energy efficiency and reduces energy consumption the possible reduction in boiler output as a result there can actually be excess installed capacity in the boiler house. The feasibility of co-firing is calculated with levelized cost of energy analysis.

Towards Carbon Neutral Combustion. LCOE Analysis of Co-firing Solid Particles and Gaseous Fuel in Latvia

One of the main obstacles to transfer to carbon neutral energy management is technological transition. An important task is to change fuel used in the boiler furnace from natural gas (fossil fuel) to biomass. The easiest but most expensive solution is the installation of a biomass boiler. Other solutions include burner replacement or additional installation, but these options are more complex from an engineering and technical point of view.By replacing natural gas with wood particles, boiler output is reduced, because the value of combustion heat, furnace load and specific combustion parameters are lower, as well as the temperature and pollution with nitrogen oxides NOx decrease. It is especially important when energy end user improves energy efficiency and reduces energy consumption. As a result there is excess installed capacity in the boiler house.The feasibility of co-firing is calculated with Levelised Cost of Energy analysis.

Performance and Operation Analysis of a Quadra Sectors Rotary Airheater Adopted by CFB Boiler

Based on the aspects of thermal properties, resistance properties, air Leakage Control and boiler output adaptability, the operation modes and their impact of a quad-sector rotary airheater adopted by a 330MWe circulating fluidized bed boiler are analyzed by tests. And the operation methods of Leakage Control System are concluded. In order to improve the reliability of rotary airheater with main and auxiliary motors, recommendations for improvement are extended.