Boiler Unit Research Articles

Energy Efficiency Improvement Strategies for Boilers: A Case Study in Pharmacy Industry

Energy resources are gradually scarce and expensive. Raised a gap between increasing demand and energy supply. Bridging gap of demand together with energy supply by increase energy supplies is a very costly decision. Moreover, in the industrial sector with the high cost of energy, the longer the competitiveness decreases. Energy costs in total production costs reduce the number of profits each year. The strategy to prevent these problems is by increasing the efficiency of industrial operations and equipment. Several stages of the efficiency process begin with identifying balance, energy-saving opportunities, and energy utilization. This stage is better known as an energy audit. The advanced stage of the energy audit helps identify potential energy conservation and encourages the industry to focus on efficiency and conservation and is supported by adequate financing. In the research strategy, the opportunity to save energy costs in oil boiler units is practical, sustainable and economically feasible. On the results of measurements and calculations obtained boiler efficiency of 53.67% where the factors that cause the low efficiency of this boiler are the high excess water by 17.32% and heat loss from dry exhaust gas by 42.03%. The solution is done by controlling excess air by regulating the air entering the combustion chamber. In this way, energy savings can be increased by 15%.

Влияние балласта на эффективность теплообмена в зоне интенсивного горения котельных агрегатов

The paper reviews the process of preparing and feeding the combustibles in the context of how combustion occurs in the furnaces of boiler units; the review helps define the requirements to the fuel flow and composition. At various steps, the fuel flow is mixed with excess air and ballast water, which affects heat transfer and combustion processes occurring in the boiler. The role of ballast is analyzed in two steps: first the paper finds how excess air affects the flow and the radiation properties of the products resultant from the combustion of fuels of three different compositions. Then the paper calculates the combined effects of excess air and ballast water on the eigen-radiation flux in the combustion of coal, sulfuric fuel oil, natural and industrial gases. Estimates use the fundamental coefficients of conservation laws as well as the reference data on the properties of the considered fuels. Analysis has found the complex reduction in gas temperature which we herein refer to as the coefficient of thermal depression. Given that coefficient, the paper presents the eigen-radiation fluxes for four model fuels and discusses the applicability of research results.

Evaluation of soil contamination by heavy metals in the zone of TPP influence

Abstract. Thermal power engineering takes one of the first places by the scale of the impact on the environment. Thermal power plant emissions are mainly deposited on the ground. Soil compounds, binding heavy metal ions (НM) for a long time, prevent their migration. The buffer capacity of the soil for metals depends on many factors: soil composition, acidity, complexity, oxidation–reduction,sorption–desorption, etc. Examination of the HM content in the soils is necessary for monitoring the environment, its protection from pollution. One of the largest pollutants in Kharkiv region is Zmiiv TPP. The goal of the work is to find out peculiarities of heavy metal contamination of the soil near the Zmiiv TTP and develop recommendations on improving the situation. In order to reach the goal, the following tasks have been solved: features of accumulation of various heavy metals in the soils have been specified, dependence between the soils pH and presence of certain chemical elements in them has been defined, dependance between the content of contamination and development of slow soluble compounds in the soil has been studied. Research methodology. The main principle of control for soil contamination is checking of concentration compliance with the established maximum permissible concentration (MPC) and approximate permissible concentration (APC). HM concentrations in the aqueous extract from the soil were determined by the atomic-emission spectral analysis, atomic absorption analysis and by the method of capillary electrophoresis. To determine the composition of the solid inorganic part of soils X-ray phase analysis was performed. Results of research. It is established that the most polluted areas are located within 10 km from TPP. The most disseminated pollutants in the area are Cu, Br, Co, V, Cr. The soils of the Siverskyi Donets Basin retain Cu, Zn and Pb ions to a large extent. Scientific novelty. Metals V, Cr are anionogenics, acid residues are formed in slightly alkaline soils and together with HM they form insoluble or slightly soluble compounds leading to their accumulation. Compounds SrCrO4, SrCr2O7, Sr(VO3)2, Zn2V2О7, Zn3(VО4)2, Zn(VО3)2 were found in the soils. Based on the determination of the coefficients of poly-elemental contamination, it is shown that maximum concentrations of HM are higher and variations of concentrations are wider except Pd, Zn and Cd in the soils with high humus, buffering and ability to form complexes with metal ions. The correlation relationships between pH, macro- and і microelements in various soils are determined. The highest correlation coefficient is between Al concentration and pH (0.6-0.9). Practical significance. Recommendations have been developed to reduce the level of soil contamination near Zmiiv TPP: reconstruction of the boiler unit, installation of an electrostatic precipitator to collect ash, using ash and slag waste in the production of Portland cement, liming soil for discrimination of HM.

New Theoretical and Methodological Approaches to the Study of Heat Transfer in Coal Dust Combustion

The existing theories of heat transfer in combustion chambers of boiler units fail to take into account a number of important factors that affect the reliability of results, and the methodological approaches to optimizing combustion processes can be revised in view of the spatial and temporal parameters of flame. Hence, the research aimed to improve the fundamental theoretical and methodological principles of studying heat transfer in coal dust combustion in the combustion chambers of industrial steam generators. The authors proposed to extend the theory of heat transfer with the mathematical description of particle size distribution of coal dust. In addition, the authors used the developed mathematical model of coal dust combustion based on a continuous curve of the particle size distribution in the ensemble. The mathematical model is consistent with the aeromechanical and thermal characteristics of flame. This work introduced a concept of flame continuum as a continuous medium, where the processes of combustion and heat transfer are studied. To achieve the research aim, in this paper, the methods of combustion chamber zoning, the equations of stationary and non-stationary heat conduction, radiation, and convective heat transfer, were used. These methods were tested on a number of high-temperature units.

ESTIMATION OF REDUCTION OF NITROGEN OXIDES IN COMBINED STEAM AND GAS POWER PLANTS

The characteristic of the united power system of Ukraine, based on thermal, nuclear and hydro power plants, as well as on alternative and renewable sources, is carried out. The structure of power system potential indicates a lack of maneuver capacity, some plants are of low mobility. Thermal power is in critical condition due to expired service time of the main technological equipment, additionally, it is a huge source of emissions of harmful substances into the environment. An attempt to use them to cover peak loads only worsens their critical state.It is suggested to restore thermal power on the basis of combined steam and gas power plants. Moreover, for operation of gas section it is necessary to use working substance, which is formed in an additional furnace by heating the compressed air with heat from combustion of some part of coal flow, which subsequently enters the main furnace. The steam and gas generation branches are parallel connected, which extends the range of power change (increasing its maneuverability.) Gas generation increases mobility (rate of power change). For combustion of organic fuel, oxygen enriched atmospheric air is fed, and a nitrogen-based fraction can form a working substance for gas generation. With such an organization of combustion the coefficient of excess air can be ignored, which enables to reduce the volume of flue gases. The membrane separation of atmospheric air into fractions - one en-riched with oxygen, and another with nitrogen, improves the environmentalperformance of a power plant, while increasing its power and economic indices. On the example of the boiler unit TP-92 the basic parameters of a power plant are checked by a calculation method. It is confirmed that the proposed technical solutions point to the correctness and validity of the assumptions. Analysis of the existing technical level of scientific research increases confidence in perspective of the selected direction.

Optimal robust operation of combined heat and power systems with demand response programs

Efficiency improvement of generation units with different scales in energy systems has always been considered as an important issue. In conventional power systems, a big share of energy portfolio (40−60%) could be wasted since generation systems are not capable to efficiently use input energy. One solution to this problem is to incorporate combined heat and power (CHP) systems to form a multi-carrier energy hub and increase energy efficiency. In this paper, an optimization framework is developed for optimal operation of a CHP system in an uncertain environment considering demand response actions. The examined CHP-based energy system is composed of a gas turbine, heat pump, storage systems and boiler units to generate heat for space heating (SH) and domestic hot water (DHW) demands. Robust optimization framework is also employed to determine the true operating mode of CHP system (namely risk-averse, risk-neutral, or risk-taker) in the examined uncertain environment. Furthermore, a time-of-use (TOU) price-based demand response program (DRP) is used to enhance system’s economic operation by changing the energy consumption pattern of end-users during the study period. Simulation results demonstrate that without DRPs, robust operation of CHP-based microgrid is obtained against 30% of more electrical load by experiencing 10.048% more operation cost while the same degree of robustness is obtained by experiencing 10.019% more operation cost considering DRPs.

Planning Method of Regional Integrated Energy System considering Demand Side Uncertainty

Abstract In this paper, a robust planning method of regional integrated energy system (IES) considering the uncertainty of cooling, heat and electrical loads on the demand side is submitted. First, the energy hub (EH) model of regional IES with Combined Cooling Heating and Power (CCHP), electric air-conditioning unit (EC) and gas boiler (GB) is established. Second, the uncertainty of load is described by the method of adjustable interval, and the robust planning model of regional IES is formed. Third, the robust programming model can be transformed into a convex mixed integer planning model, and then solved. Finally, the case study is carried out with a comprehensive area of Tianjin in China, the results are analyzed to verify the effectiveness of the proposed planning method.

Real-time price-based demand response model for combined heat and power systems

Real-time electricity pricing could promote the adaptation of demand response programs in the presence of price volatility in smart grids. This paper proposes a real-time price-based demand response management model for heat and power consumers. In the proposed demand response program (DRP) the responsive electrical load can vary in different time intervals. In addition, total power and heat demands of the consumer are met, without any curtailment. The price uncertainty is envisaged through robust optimization for minimizing the worst-case electricity and heat demand procurement cost while flexibly adjusting the solution robustness. The proposed model can be easily embedded in the energy management system of the customer equipped with combined heat and power systems (CHPs), a power-only unit, a boiler unit and a heat buffer tank (HBT) and makes it possible to achieve a minimum cost. In this paper, the dual dependency characteristic of the heat and power in different types of CHPs has been taken into account. Furthermore, technical constraints, i.e. minimizing number of start-ups and shut-downs, ramp rate limits and minimum up/down-time limits of generation facilities are satisfied. Numerical simulations confirming the applicability and effectiveness of the proposed model are provided. According to the simulation results, there is a significant increase in the daily cost of the consumer without smart grid technology in comparison with the consumer employing the proposed real-time model.

On a certain method of power boiler blast air pre-heating

The method for preliminary heating of boiler blast air has been developed; as per this method, the air before being blown to boiler air heater is pre-heated with exhaust natural gas combus-tion products in surface heat exchanger with combustion products cooled below dew point temperature. It is suggested to use water vapor condensate produced by this process as heat system make-up water. Thermal calculation for condensing heat exchanger installed down-stream of BKZ-420-140 NGM power boiler is made, as a result of the calculation, the following parameters were obtained for different values of ambient air: heating power of heat exchanger; consumption of exhaust gases for pre-heating of boiler blast air provided that they are cooled below dew point temperature; proportion of exhaust gases transferred to heat ex-changer; consumption of water vapor condensate produced from gas fuel combustion prod-ucts; temperature, moisture content and dew point of exhaust gases on exit of boiler unit; in-crease in boiler fuel consumption coefficient due to operation of condensing heat exchanger; heat transfer coefficient. Cost effectiveness due to pre-heating of BKZ-420-140 NGM boiler blast air in condensing surface heat exchanger at Samara Power Station has been determined.

A novel operation cost optimization system for mix-burning coal slime circulating fluidized bed boiler unit

At present, mix-burning of coal slime in a circulating fluidized bed boiler is an effective method to cleanly utilize low-price coal slime. This study proposed a data-based operation cost optimization system for mix-burning coal slime CFB boiler unit that instructs operators to more scientifically adjust the operation parameters. Based on actual operating data from a 300 MW CFB unit, least squares support vector machine was used to build the steady-state operation cost model, and partial mutual information variable selection method was applied to choose the input variables and lower the model complexity. Based on the pre-built operation cost model, the genetic algorithm was used to establish an offline expert knowledge database within the safety threshold range. The utility cost was introduced into association rule measurement standards to improve the traditional fuzzy association rules mining. The improved fuzzy association rule mining was used to extract the associations between the unit load and the optimal operation parameters from the off-line expert knowledge database after receiving the load instruction, so as to achieve fast instruct on online operation optimization. Results showed that the proposed economic optimization system performances were better than traditional methods and can improve operation of the unit being studied.

Экспериментальное исследование пульсационных характеристик закрученного потока в модели четырехвихревой топки

Актуальность исследования обусловлена необходимостью вовлечения в топливно-сырьевую базу низкосортных высокозольных углей в связи с ограниченностью запасов высококачественного топлива. Для их эффективного и экологически безопасного использования требуется разработка новых и модернизация имеющихся котельных агрегатов с предварительным физическим и численным моделированием. Целью работы является экспериментальное исследование пульсационных характеристик турбулентного закрученного потока в модели перспективного топочного устройства, использующего четырёхвихревую схему сжигания пылеугольного топлива. Объектом исследования является изотермическая лабораторная модель четырёхвихревой топки, выполненная из оптически прозрачного оргстекла для проведения измерений в рамках современных бесконтактных методов диагностики потоков. Методы: физическое лабораторное моделирование аэродинамики и процессов переноса в четырехвихревой топке; бесконтактное исследование осредненных и пульсационных характеристик в объеме модели топки при различных режимных параметрах; исследование пульсаций давления с использованием конденсаторного микрофона. Результаты. С использованием метода цифровой трассерной визуализации получены распределения осредненных и пульсационных характеристик скорости потока в ряде сечений модели в широком диапазоне режимных параметров. Определено положение зон с высоким значением турбулентных пульсаций и застойных зон, установлены особенности их расположения в зависимости от режимов. С использованием конденсаторного микрофона получены данные о пульсациях давления в локальных областях объема модели. Анализ спектральных характеристик с применением к полученным данным преобразования Фурье показал, что в изучаемой модели отсутствуют нестационарные периодические колебания, связанные с прецессией вихревого ядра потока. Измеренные пульсации давления вызваны акустикой, пульсации скорости носят случайный характер и не связаны с динамикой когерентных структур.

Increasing efficiency of boiler unit by installation of gas-piston micro central heat power plant

The article is devoted to ways of increasing the efficiency of boiler houses producing heat in the form of hot water. The problems of the shortage and uninterrupted power supply are also touched upon. One of the methods for solving the problems is using gas piston engines and reconstructing the boiler house into a micro gas-piston power plant. Installations of this type can be used for production of various types, including at enterprises of the energy sector and the mineral-raw complex. Ways to improve the existing equipment are considered. The possibilities of using economic analysis for determining the installation location and the choice of the number and power of the gas piston unit are shown. The properties of the intermediate heat carriers of the gas piston engine are different depending on the required temperature of the heat carrier - hot water.

Features of Using the Regulatory Method "Thermal Calculation of Boiler Units" for Firetube Boilers

Features of Using the Regulatory Method "Thermal Calculation of Boiler Units" for Firetube Boilers

Development of a Neural Network for a Boiler Unit Generating Water Vapour Control

This article raises the question of neural networks application to control a boiler unit as a multidimensional system. The use of neural networks for managing technological processes helps to solve the problems of the operation of a complex control system, it improves its fail safety. The article proposes to apply a neural network to solve these problems. Technological process as a multidimensional system has been studied and described, the algorithm of the boiler has been described, neural network for controlling a boiler designed to produce water vapour under pressure has been developed, trained and tested. Development, training and testing of the neural network was carried out in Matlab program.

DEVELOPMENT EXPERIENCE OF MODERN MADE IN RUSSIA BOILER INSTALLATIONS

Based on the results of adjustment, testing and industrial development of the main models of boiler units commissioned by Russian thermal power stations in recent years, the level of the domestic boiler plant is shown. The ways of improving these head samples are outlined. Prospective directions of development of domestic boiler plants are given, to which special attention should be paid to scientific research organizations and boiler plants.

Analysis of the Efficiency of Using the Heat of Natural Gas Combustion Products to Preheat Forced Air Supplied to the Boiler

Preheating of forced air in a surface-type heat exchanger prior to supplying it to the air heater of the boiler by using flue gases while cooling them below the dew point is proposed. Athermal calculation of the condensing heat exchanger installed downstream of the boiler (model BKZ-420-140 NGM) was performed to determine the thermal capacity of the heat exchanger, flow rate of flue gases required to preheat forced air supplied to the boiler while cooling them below the dew point, flow rate of the water vapor condensate obtained from the gaseous fuel combustion products, temperature of flue gases at the outlet of the boiler unit, and fuel utilization factor of the boiler resulting from the use of the condensing heat exchanger. The water vapor condensate obtained from flue gases in the surface heat exchanger can be used as make-up water for the heat network. It was established that depending on the ambient air temperature, the percentage of flue gases directed to the heat exchanger for preheating forced air of the BKZ-420-140 NGM boiler assuming their cooldown below the dew point constitutes 3.9 to 20.7 and 7.6 to 24.4% of their total amount, when heating air to 20 and 30°C, respectively. The economic effect in the monetary terms due to installation of the condensing heat exchanger downstream of the BKZ-420-140 NGM boiler amounts to 12, 691.7 and 17,242.2 thousand RUB/year, when heating forced air to 20 and 30°C, respectively. Considering five power-plant boilers installed at the Samara CHP operated by “Samarsky” branch of the PJSC “T Plus,” the amount of savings should reach 63.5 and 86.2 million RUB/year, respectively.

Effect of fine ash particles on formation mechanism of fouling covering heat exchangers in coal-fired power plants

The 1-D model of thermodynamic iterative calculation is put forward for the prediction of acid condensation considering the complexity of flue gas. The radius of fine ash particles is dominant for condensation rate around fine ash particles at ADP; flue gas components for ADP, critical radius, and condensation rates, especially acid vapor content of flue gas. X-ray fluorescence (XRF) and scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) are used to analyze the ash samples collected during the field experiment of a 300 MW sub-critical coal fired boiler unit, i.e. fly ash deposits (>130 °C), dry loose ash deposits (85 °C) and viscous ash deposits (65 °C). The results show that S distribution is connected with the distributions of superfine particles and fine particles, especially superfine particles, which are dissolved in viscous ash samples. According to the experimental results and acid condensation analyses, the presence of fine ash particles (dash < d0) is the primary factor for the acid condensation at ADP and the coupling mechanism of the sticky ash particles. In the waste heat utilization system, the on-line monitoring of the sub-micron ash particles can be added to reflect the low temperature corrosion.

ТЕХНИКО-ЭКОНОМИЧЕСКИЕ АСПЕКТЫ КОГЕНЕРАЦИИ УГЛЕВОДОРОДНЫХ ГАЗОВ

&#x0D; &#x0D; &#x0D; The subject of researches are the regularities of the effective operation of information, resource and energy saving technology for the gases utilization from coal mines and metallurgical industries. The aim of the work is to present the technical and economic aspects of the information resource and energy saving process for the gases utilization from coal deposits and mines. As the result, the information about a new method for increasing the accuracy of automated commercial metering of coal gas, supplied to the Ukrainian gas-transport system, was provided, the regularities, governing the energy efficiency of controlling of the air/gas ratio from the oxygen concentration in the flue gases of the boiler unit, and the criterion of energy-efficient management were established. The calculation of the expected annual economic effect from the implementation of the control station “DIYA”, using the presented developments, was given.&#x0D; &#x0D; &#x0D;

Operational control of an integrated drum boiler of a coal fired thermal power plant

Boiler in thermal-power-plant plays important role in generation of power. Conventional subcritical-boilers use single-loop controls which are less efficient. An effective control of temperature and pressure of boiler is necessary to enable safe power generation. This article discusses application of three different multivariable-control strategies, namely, PID (Proportional-Integral- Derivative), MPC (Model Predictive Controller) and Inverse-decoupling-control to the individual units of boiler (economizer, drum, super-heater) as well as to the integrated boiler unit of the coal-fired thermal-power-plant separately. The mathematical-model derived based on mass-balance and energy-balance equations of economizer, drum and superheater units are used for the synthesis of controller. The non-square nature of mathematical-model carries complexity in the design of controllers. The performances, based on minimization of objective-function containing closed-loop error along with the control-effort of individual and integrated units, of the boiler using IMC (Internal-Model-Control) based PID, Inverse-decouple and MPC in the presence of disturbances are analyzed and compared. The results show that multi-loop control of integrated units ensures asymptotic-stability compared to unstable single-loop control and the controller needs to take less effort in the case of the integrated unit compared to the individual units. The results suggest for implementation of integrated multi-loop control instead of controlling individual boiler units.

Synergetic effects of firing gases/coal blends and adopting deep air staging on combustion characteristics

The synergetic effects of firing gases/coal blends and simultaneously adopting deep air staging on combustion characteristic parameters, such as furnace temperature, burnout of coal and NOx emissions, were firstly experimentally studied and numerically simulated in a 300 MWe unit boiler. The improved multiple surface reaction model, which included pore diffusion resistance of gas phase in ash, was proposed in this paper to simulate actual char combustion. The simulated results quantitatively showed that the proposed model solved the problem of seriously inaccurate calculation of unburned carbon in fly ash for the numerical simulation of multifuel combustion. Under the conditions of firing coal/gases blends and adopting air staging, the models of pulverized coal pyrolysis, coke gasification and gas combustion were established because the reduction atmosphere is formed in the primary combustion zone of the furnace. The reduction of NOx by reductive gases produced from co-firing gases, pulverized coal pyrolysis and coke gasification was considered in numerical simulation. All the numerical models adopted in this study were reasonably validated on the basis of comparing the simulation and experimental results. The temperature field, velocity field, flue gas components, coke burnout, NOx formation and reduction characteristics of three conditions (coal-fired condition, adopting deep air staging condition and firing coal/gases blend and simultaneously adopting deep air staging condition) were studied numerically. After firing coal/gases blend and adopting deep air staging, the furnace temperature field was fairly well-distributed; the average velocity of flue gas decreased lower; the reducing atmosphere zone was found to be lengthened by comparing the concentration of oxygen and carbon monoxide; and it could be concluded that there was more time for the combustible matter burning-out and NOx reduction. The temperature field and reducing gases distribution profile along the furnace height are disadvantageous for generating NOx and beneficial to reducing NOx. The results clarified the complex synergistic effect of firing coal/gases blend and adopting deep air staging on combustion characteristics, which could be applied to increase the boiler performance and optimize the co-firing technology.