Energy Efficiency Of Boilers Research Articles

Energy efficient modernization of KVG and TGV boilers

At present, the district heating systems of Ukrainian cities are in a critical state. They need significant modernization. This especially applies to very important components of district heating systems – heating water boilers. Unsatisfactory condition of boilers is mainly due to the obsolescence of basic equipment, including boilers. The operating time of them exceeds the passport lifetime. There ia a lack of modern automation, especially in terms of controlling operating modes. Nominal power of them exceeds the real heat loads. The range of hot water boilers used is not large. These are low-power boilers of the series NDIST, "Universal", "Energiia", "Fakel" and others, medium-power boilers of the series TVG and KVG and high-power boilers of series PTVM and KVGM. According to their prevalence, special attention should be paid to boilers of the series TVG and KVG. The series are installed on quarter boiler houses. The boilers of these series have an efficient design of the furnace volume and an optimized design of the convective part. Nevertheless, in terms of automation, gas supply and air supply systems, they no longer meet today's requirements. They are outdated comparing to the achieved level of technical solutions. The article discusses the main shortcomings of the design of boilers: insufficient durability of the gas collector in the hearth burner, small diameter of the pipes of the convective part and the use of fireclay materials in the setting of the burners. The first two shortcomings were overcome by the developers by the increase in the diameter of the pipes of convective packages and the modernization of MPIG-3 hearth burners. The third shortcoming should be overcomed by replacing the setting with a modern one during off-season repairs. Reserves for improving the energy efficiency of boilers of these series are found. To do this, it is necessary to install additional convective heating surfaces (economizers or air-heaters), replace the setting and equip the boilers with a modern automation system with cascading the burners. It allows improving efficiency up to 94...95 % and environmental performance according to the modern requirements.

Investigations on the energy efficiency limits for industrial boiler operation and technical requirements—taking China’s Hunan province as an example

Specially tailored energy efficiency standards are critical for the energy-saving of local industrial systems. We take the Hunan province as a concrete example, and select its industrial boiler as the study subject based on the survey results of Hunan’s leading industrial structure. Effective energy and exergy quantitative analysis methods were applied to obtain the efficiency of the target industrial boilers. Combining the corresponding reference standards with the exergy & thermal efficiency, the analytic hierarchy process, and uncertainty analysis results, we propose a reasonable regional industrial boiler energy efficiency standard. Additionally, the main factors affecting the industrial boiler system were distilled and ranked: 1-exhaust gas temperature, 2-fuel volatile matter, 3-air coefficient, 4-boiler capacity, 5-cold air temperature, 6-slag carbon content, 7-slag temperature. These results could provide a theoretical foundation for designing further energy-saving renovation projects of the industrial boiler system.

Performance Investigation of Steam Boiler of PLTU Tello Makassar Using Energy – Exergy and Entropy Balance Approach

The aim of this work is to investigate the performance of boiler of power plant in Tello Makassar. The boiler generated an electricity power of 50MW to fulfil the electricity needed of people in Makassar city. Performance investigation of the steam generator is very important due to the operation of the boiler is a long time since 1971. The methodology in this study using energy and exergy analysis as well as entropy generation approach. The methodology will be applied in all boiler components namely; Combustion Chamber, evaporator, superheater IA, superheater IB, superheater II, air heater I, economizer and air heater II. The result shows a significant decrease in efficiency of energy and exergy for superheater II of 28.98% and 21.28% respectively. The performance of superheater I and air heater II shows energy efficiency above 90%, while the exergy efficiency are less than 50% for both of components. The economizer were in the middle performance by placed the efficiency of energy and exergy in 64.48% and 48.35% respectively. In general, boiler components are working very well by reach energy efficiency of 90% in average. However, by applications the exergy analysis the performances of the components does not touch of 50%. The result of the study also shows the energy and exergy efficiency of boiler are 41.96% and 29.36% respectively. Meanwhile, the heat that is inducted to the steam turbine are 35.98MW and 15.12MW by energy and exergy analysis when the plant was working on 10.3MW of a load.

Integrated study of flue gas flow and superheating process in a recovery boiler using computational fluid dynamics and 1D-process modeling

Superheaters are the last heat exchangers on the steam side in recovery boilers. They are typically made of expensive materials due to the high steam temperature and risks associated with ash-induced corrosion. Therefore, detailed knowledge about the steam properties and material temperature distribution is essential for improving the energy efficiency, cost efficiency, and safety of recovery boilers. In this work, for the first time, a comprehensive one-dimensional (1D) process model (1D-PM) for a superheated steam cycle is developed and linked with a full-scale three-dimensional (3D) computational fluid dynamics (CFD) model of the superheater region flue gas flow. The results indicate that: (1) the geometries of headers and superheater platens affect platen-wise steam mass flow rate distribution (3%–7%); and (2) the CFD solution of the 3D flue gas flow field and platen heat flux distribution coupled with the 1D-PM affect the platen-wise steam superheating temperature (45%–122%) and material temperature distribution (1%–6%). Moreover, it is also found that the commonly-used uniform heat flux distribution approach for the superheating process is not accurate, as it does not consider the effect of flue gas flow field in the superheater region. These new observations clearly demonstrate the value of the present integrated CFD/1D-PM modeling approach.

Generalized Energy and Ecological Characteristics of the Process of Co-Firing Coal with Biomass in a Steam Boiler

One of the ways used to reduce the emission of carbon dioxide and other harmful substances is the implementation of biomass co-firing processes with coals. Such processes have been implemented for many years throughout many countries of the world, and have included using existing high-power coal boilers. Despite numerous experiments, there are still no analyses in the literature allowing for their generalization. The purpose of this paper is to determine the generalized energy and ecological characteristics of dust steam boilers co-firing hard coal with biomass. The energy characteristics determined in the paper are the dependence of the gross energy efficiency of boilers on such decision parameters as their efficiency and the share of biomass chemical energy in fuel. However, the ecological characteristics are the dependence of emission streams: CO, NOx, SO2, and dust on the same decision parameters. From a mathematical point of view, the characteristics are approximation functions between the efficiency values obtained from the measurements and the emission streams of the analysed harmful substances and the corresponding values of the decision parameters. Second-degree polynomials are assumed in this paper as approximation functions. Therefore, determining the characteristics came down to determining the constant coefficients occurring in these polynomials, the so-called structural parameters. The fit of the determined characteristics was assessed based on the coefficients of random variation and the test of estimated significance of structural parameters. Boiler characteristics can be used when forecasting the impact of changes in operating conditions on the effects achieved in existing, modernized, and designed boilers. The generalization of the characteristics was obtained from the measurement results presented in 10 independent sources used to determine them.

Thermal Analysis of Steam Power Plant of High Capacity

Steam power plants are widely utilized throughout the world for electricity generation, and coal is often used to fuel these plants. To utilize coal more effectively and competently in electricity generation processes the energy optimization is required. Thus the thermal analyses of different components are performed to improve efficiency and performance. Present work deals with the thermal analysis of 600 MW steam power plant. The energy efficiency of boiler, turbine and condenser are found to be 63.05, 48.25 and 92.67 respectively. Similarly the respective exergy efficiencies are 52.69, 88.25 and 18.5 for boiler, turbine and condenser. The results indicate the exergy reduction of steam is high in condenser showing low efficiency. The energy loss of steam in the condenser can be compensated by adopting binary power generation cycles.

DESIGN AND IMPLEMENTATION OF AN AUTOMATIC CONTROL SYSTEM TO AVOID FOULING IN PIPES WITH BLOW DOWN HEAT RECOVERY IN STEAM BOILERS

The aim of the present work is to solve the problem of fouling in boiler pipes and improve energy efficiency of steam boilers in the south refineries company, Al-Basrah province, Iraq. An automatic control system with a novel electronic circuit has been proposed to achieve this aim. This system consists of an on-line conductivity sensor and a conductivity monitor connected to an additional resistance to measure the concentrations of dissolved solids in boiler water. A square wave feedback has been employed to determine the levels of solid concentrations and controls the surface blow down process through electronic circuit. This circuit consists of a D.C power supply, an amplifier, a rectifier, comparators and a driver sub-circuits for solenoid valve. The driver sub-circuit consists of two transistors and three relays. The solenoid valve is used with throttle valve to control the flow rate of boiler blow down water. Two flow meters are used to measure blow down and feed water flow rates. The design and implementation of a heat recovery unit is also included. It consists of a heat exchanger (shell and coiled tube) type used to recover heat energy from blow down water. To measure the inlet and outlet temperatures of feed water and blow down water, four (k-type) thermocouples were used. A pump was used to pump feed water from the storage tank in to the boiler. To automatically control water level inside the boiler two electrodes (water level sensor) were used integrated with the float less level switch circuit. The experimental results proved the effectiveness of the innovative control system in improving boiler efficiency and in fouling control through enhancing the blow down process and reducing indirect losses. The blow down quantity reduced from 2244.897 kg/h to 1111.111 kg/h. Which provided 27210.864 kg/day of blow down water. Hence, saved 158450201.2 ID/year or 83.16% of the energy lost with blow-down water can be recovered using heat-recovery unit with an energy saving of 103411.8 MJ/day. Which will save a mass of fuel equals to 482.46 ton/year. The automatic control system proved to be a good solution for saving energy and reducing harmful emissions to the environment and it contributes to the maintenance of sewage pipes from damage caused by the heat of discharged water.

Calculation methods of steam boiler operation factors under varying operating conditions with the use of computational thermodynamic modeling

Paper presents the results of pulverized coal-fired steam boiler analysis under varying operating conditions. To investigate the efficiency of the analyzed steam boiler, the energy and exergy analysis was conducted, as well as the basic operating conditions of the flue gases-air and water-steam circuit were determined. To calculate boiler energy efficiency, the indirect method and individual boiler losses computation was applied. The thermodynamic model was developed to simulate boiler operation under partial boiler loads. The accuracy of the model results was verified at three different partial loads. The thermodynamic model was created using Ebsilon Professional software and a 0-dimensional thermodynamic modeling approach. The results in the form and steam temperature distributions at the outlet of all heating surfaces have been verified with available boiler measurement data. The relative error of steam temperature calculation doesn’t exceed 4.5%. The developed model allows performing calculations for variable input conditions in order to determine the basic parameters of the boiler operation and total boiler efficiency. The presented calculation methods were applied to identify the changing of boiler efficiency and basic boiler parameters during operation with under different partial loads and during the burning of different coal types. The various operating conditions have a great impact on boiler performances. Energetic and exergetic analysis carried out for boiler operating parameters were used to evaluate total boiler efficiencies. The results were presented in the form of total boiler efficiency and boiler losses as in the function of boiler load and calorific fuel value.

Investigation of Methods for Increasing of Energy Efficiency of Hot Water Boilers of Small and Average Capacity at the Expense of Reduction of Heat Losses with Exit Gases

Boiler units, being a considerable time in use, lose their effectiveness and even the high-quality performed commissioning works, are not always able to increase the efficiency (coefficient of efficiency) of such unit up to the declared values of parameter chart. Both domestic and foreign boiler equipment have this problem. This issues is reflected in increase of exit gases temperature and, consequently, increase of value of heat losses with exit gases and decrease in efficiency of boiler unit. The purpose of the investigation is to select the most effective way to solve this problem and at the same time the least expensive in terms of investment and modernization of the used equipment. Analytical and experimental studies of q 2, the value of heat losses with exit gases, domestic and foreign boiler units of small and average capacity were carried out. The obtained results allow us to formulate recommendations for improving the energy efficiency of boiler equipment for operating organizations and for organizations on the balance of which such equipment is located.

Techno‐economic analysis of a novel hybrid heat pump system to recover waste heat and condensate from the low‐temperature boiler exhaust gas

This paper is based on the proposal of a new waste heat recovery (WHR) system, which can be utilized to heat the boiler return water, boiler supply air, and building heating air. The system is the combination of an indirect contact condensing unit (IDCCU), a mechanical compression heat pump, and two air preheaters. The system is modeled on the basis of mass and energy balance and then thermodynamically analyzed. Improved performance results were obtained in the form of an increase in the boiler's energy efficiency of about 10.47%, with 4.87% increase in exergy efficiency. The coefficient of performance (COP) of the heat pump was increased from 1.23 to 1.45 by the addition of an air heater in the conventional heat pump. The exergy destruction in each component is calculated. Sensitivity analysis was performed to check the influence of different operating parameters on the performance of the WHR system and boiler. It can be observed from the results that for a specific refrigerant temperature and a calculated amount of mass, flow rate can maximize the condensation efficiency of IDCCU by decreasing the flue gas temperature, while the use of the air heater can further reduce the flue gas temperature, and a stream of hot air can be utilized for space heating. A comparison is made with the other system on a performance basis. The results shows a clear difference in efficiencies and profit earned.

Design-Based Thermal Efficiency Correction Method for Hot Water Boiler

In the boiler design process, the thermal efficiency of the boiler operating under specified parameters is given in accordance with the design specifications. However, under the actual operating conditions, the specified parameters in the design book cannot be met at the same time. Especially for the hot water boiler, the coal quality component and the deviation of low calorific power, the feed water temperature and the ambient temperature will directly affect the operating efficiency of the boiler. In the current boiler energy efficiency test standards, the test conditions are very demanding. It is required to be the design coal type and it also gives fluctuation ranges for several parameters that affect the boiler operation efficiency. For non-design conditions, the boiler operation condition test method can only be executed referring to the standard. However, the measured efficiency is highly variable. This paper aims to analyze and study several parameters affecting boiler efficiency based on the perspective of boiler design, and give corresponding efficiency correction method to provide reference for the correction of energy efficiency test results under non-design conditions.

Promising designs of water-heating boilers is great power for centralized heat supply systems.

The article is devoted to the actual theme - an increase of energy efficiency of powerful heating boilers and heat supply stations of centralized heat supply systems of Ukrainian cities, in particular replacing their operational term and physically worn water heat boilers of high capacity.In fact, in high-power boiler-houses of district heating systems of the cities of Ukraine, water-heating boilers of two series - PTVM and KVGM are used. Both types of boilers today do not meet the needs of the market - the requirements of normative documents on the environment and on energy efficiency. In the post-Soviet countries of the Baltic and Eastern Europe, there has been a great deal of experience in modernizing these boilers in order to increase their environmental and thermal performance. In particular, due to the replacement of burners by more than one hour, reduction of their number for boilers of the PTV series, the arrangement of gas-density screen surfaces in boiler furnaces, on-the-spot molding on light fibrous materials, deep automation of boilers operation and equipment with frequency regulators of load-bearing machines. However, if it is necessary to increase the capacity of large boiler-houses, it is inappropriate to use boilers of the types of PTVM and KVGM.In the article reviewed in the technical literature, a large amount of information was analyzed with the results of studies on optimization of the design of powerful steam boilers, in particular, to optimize the design of burners in furnaces. The analysis of this information has shown that it can be used for the design of high-power water heat boilers (from 30 MW to 200 MW).On the basis of information analysis, selected directions of optimization of structures of water-heating boilers of high capacity of the location of burners in the vault or in the subsoil, the use of gas-density screen surfaces, part of which is carried out by two-colored, the use of as few modulated low-NOx burners of high power, deep automation of boilers and boiler-houses in general.The article gives an example of a conceptual design of a 120 MW water boiler using the above principles in comparison with a boiler of the same capacity, which is an upgraded variant of the boiler PTVM-100 capacity of 116 MW. The equation shows that the proposed conceptual design of a water-heating boiler has almost 2.5 times less metal capacity, almost 2 times less than height, which has much more flexibility and wide regulation, which leads to lower cost of the boiler itself and, accordingly, the cost of installation work.

Problems of calculation the energy efficiency of a dual-fuel steam boiler fired with industrial waste gases

The article presents the problems of calculation the energy efficiency of a dual-fuel steam boiler OPG-430 type operated in an industrial CHP plant fired with blast-furnace and coke-oven gases. The available special measurements were used to calculate the energy efficiency of the boiler. These measurements have been made for varying thermal loads of the boiler and different proportions of individual gases in the fuel feeding the boiler. The energy efficiency of the boiler was calculated using the direct method and the indirect method in accordance with the algorithm included in the EN 12952-15 standard. Due to the occurring measurement redundancy, advanced data validation and reconciliation of measurements in steam boiler energy balancing in accordance with the methodology included in VDI 2048 guidelines was used. Discussion of the results of the energy efficiency of the boiler calculations obtained in different variants of the use of measurement data was carried out. In addition, the energy characteristic of the boiler was developed using the stepwise regression method. Obtained results of the energy efficiency of the boiler calculations clearly showed the necessity of using balance methods with the use of advanced data validation and reconciliation method of measurements in the case of measurements redundancy.

Comprehensive technologies for increase of reliability and energy efficiency of medium capacity PTVM and KVGM hot-water boilers

This article is dedicated to the problems of reliability, long-term thermal capacity and operational efficiency rate of PTVM and KGVM hot-water boilers. Based on the analysis of statistic data, tests, and certain works on increase of efficiency and reliability of PTVM-100 tower hot-water boilers, which were performed in Kazakhstan, it may be said that the reconstruction of PTVM-100 boilers accomplished on CHP was mainly aimed at the increase of reliability while saving the operational efficiency of boilers almost without changes. If the boiler is operating on fuel oil and without periodical washes, then it is possible to achieve consistent operation only under 75% of the nominal operational load. Structural changes of the PTVM-100 boiler unit offered by authors, along with the increase of operational reliability on fuel oil and it’s thermal capacity, allow increasing boiler’s efficiency rate up to 91-92% if it is operated under nominal load and using fuel oil. Structure the new KV-GM 55 hot-water boiler with horizontal design includes the two-row bi-radiated screen wrapping around the furnace and the new arrangement of convective packs, which are now located next to each other, allowed to increase heating characteristics of the boiler significantly due to the intensification of heat exchange and decrease of temperature of gases released from behind of the boiler unit, as well as to increase boiler’s efficiency rate up to 92,5% under nominal load.

Comparative Analysis of Boiler Energy Efficiency Regulation System

Industrial boilers are increasingly used with the rapid economic development of our country, with both energy consumption and pollutant emissions ranking second in national industry sector, second only to utility boilers; their coal consumption is far higher than high energy-consuming steel, petrochemical and building material industry sectors, and their pollutant emissions caused to national key cities have exceeded that of utility boilers. In this paper, we focused on the merits and demerits of China’s industrial boiler energy efficiency indicator standards and make suggestions for improvement, specially, China industry boilers energy efficiency standards and regulation. We really think it will great promote China industry boilers energy efficiency progress.

Simulation of Velocity Field in a Pulverized Coal Fired Boiler

This paper selects a 58MW pulverized coal boiler as the research object, three dimensional physical modelling and mathematical modelling are established for the boiler furnace, according to the set of reasonable hypothesis and boundary conditions, the Fluent software is used to simulate the velocity field in the furnace under six operating conditions. Through the numerical simulation results, the optimal operating conditions of this kind of boiler are discussed, which can provide data reference for improving the energy efficiency of small and medium-sized coalfired boilers.

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%.

Fire-tube boiler optimization criteria and efficiency indicators rational values defining

Technical and economic calculations problems solving with the aim of identifying the opportunity to recommend the project for industrial implementation are represented in the paper. One of the main determining factors impacting boiler energy efficiency is the exhaust gases temperature, as well as the furnace volume thermal stress. Fire-tube boilers with different types of furnaces are considered in the study. The fullest analysis of the boiler performance thermal and technical indicators for the following engineering problem: Q=idem, M=idem and evaluation according to η, B is presented. The furnace with the finned ellipse profile application results in the fuel consumption decrease due to a more efficient heat exchange surface of the furnace compared to other examined ones.

Study on System Frame of China Industry Boilers Energy Efficiency Standards

Energy consumption is always concerned by China government, from 11th five years plan, central government and departments are trying to deduce the energy consumption and CO2 emission. Massive energy were consumed by industry boiler that pointed out by investigation of energy in China industry, standards for boilers, specially energy efficiency standards are always considered to be a key approach to reduce energy consumption and promote high energy efficiency technology. From the results of survey, industry boiler energy efficiency standards are indeed useful to reduce energy consume. In this paper, we try to research on China industry boilers energy efficiency standards, based on that we concluded the system of China industry boiler energy efficiency standards, and listed all the index of those energy efficiency standards which force to comply. It is very useful to make everyone to understand China industry boiler, and industry boiler energy efficiency standards.

Study on Laws, Regulations and Standards on Energy Efficiency, Energy Conserving and Emission Reduction of Industrial Boilers in EU

Industrial boilers are widely applied in such fields as factory power, building heating, and people’s lives; China is the world’s largest producer and user of industrial boilers, with very high annual energy consumption; clear requirements have been put forward by China on the energy efficiency since the “11th Five-year Plan” with the hope to save energy and reduce emission by means of energy efficiency standards and regulations on the supervision and control of various special equipment. So far, the energy efficiency of industrial boilers in China has been improved significantly but there is still a gap with the EU states. This paper analyzes the policies of energy efficiency, implementation models and methods of supervision and implementation at the EU level from laws, regulations, directives as well as standards; the paper also puts forward suggestions of energy conserving and emission reduction on the improvement of energy conserving capacity of industrial boilers in China through studying the legislations and measures of the developed countries in energy conserving of boilers.