Single Boiler Research Articles

Steam Boilers in Ready-Made Garments Industry in Bangladesh: Existing Scenario and Scope for Development

Bangladesh's Ready-Made Garments (RMG) industry, historically prone to hazards including boiler explosions with numerous fatalities, has prompted the RMG Sustainability Council (RSC) to initiate boiler safety inspections. This study addresses the lack of empirical data on boiler operations in RMG factories, focusing on operational scenarios, risk factors, and remediation strategies. Conducted from March 2021 to March 2023, structured visual inspections across 1386 RMG factories assessed 2204 boilers. Key findings reveal that 34.99% of factories predominantly use a single boiler, 91.24% of boilers are government-registered, and the majority are imported (63.29%) with a steam generation capacity below 1,000 kg/hr (59.75%). Additionally, 63.11% were manufactured between 2010 and 2019, 79.63% burn fossil fuels, 54.60% are vertically oriented, and 82% use softened feedwater. The study also identifies 32 external risk factors across 11 categories, providing insights for decision-makers to enhance boiler operation safety and sustainability. By leveraging this inspection data, the research aims to bridge the empirical gap and offer a comprehensive understanding of the existing challenges in RMG boiler operations. Journal of Engineering Science 14(2), 2023, 89-105

Integrated thermal modeling, analysis, and sequential design of heat exchanger surfaces of a natural circulation RDF boiler including evaporator tubes

Although the design methodology of individual heat transfer surfaces in a natural circulation boiler such as evaporator tubes, convective and radiative superheaters are available in the literature, the multiple feasible design solutions of boiler heat exchanger surfaces coupled with drift flux based model of evaporator tube and cost-based optimal solution of the surfaces is not common. The present study proposes a sequential iterative design methodology for all heat transfer surfaces (from the evaporator to air preheater) in a single boiler to bridge the gap between industrial needs and academia. The salient temperature points in different locations are used in the design, alternate solutions are considered, and the overall cost is minimized. The evaporator tubes are designed based on a two-phase flow drift flux model and fixed volume constraint. The radiant and radiative-convective superheaters are modeled using weighted average flue gas temperature. The models of evaporator section and other heat exchangers are validated extensively with data of natural circulation loop and components integrated into real plants, respectively. The feasible and optimal design solutions of all heat transfer surfaces are proposed for a medium-scale (35 MW) Refused-Derived Fuel-fired Boiler (RDFB). The variation of mass flux through the evaporator tubes with the fuel feed rate is observed to be gravity-driven initially followed by friction-dominated. It is observed that for lowering the exit flue gas temperature of 14.93% below 150 °C, the required area of air preheater is 21.83% higher, while for a reduction of temperature of 21.42%, the area increment is 55.8%, which increases the investment cost rapidly. Results also indicate that the radiative heat exchangers require less heat transfer surface for a higher pitch to diameter ratio while the opposite characteristic is observed for the convective heat exchangers.

Economic analysis and cost modeling of supercritical CO2 coal-fired boiler based on global optimization

Boiler is one of the critical equipment to realize supercritical carbon dioxide coal-fired (SCDC) power, but there is a lack of cost evaluation method. In this study, an improved global optimization model which is composed of genetic algorithm, thermal calculation and levelized cost of electricity (LCOE), was designed to obtain the optimal design of SCDC boilers. The cost curve of boilers with different capacity (350–1000 MW), temperature (600–650 °C) and pressure (300–330 bar) was analyzed and a new correlation of boiler cost was given. Due to the influence of heat transfer and material, the boiler cost firstly decreases and then increases with the increase of thermal power. For a single boiler, thermal power of 1000-2000 MWth is a suitable choice. Temperature affects boiler cost through thermal power and material strength, which are reflected by “r2t” and “r7t+r8“. Furthermore, double/multiple boiler design and positive matching principle were proposed to ensure the cost was in optimal range. These two schemes can provide the basis for selecting boiler parameters. The SCDC boiler cost increases by 32 % compared with the traditional steam boiler. SCDC units that meet the positive matching principle can achieve lower LCOE. This study can provide reference for the design of SCDC system.

Analysis of heat losses during heat supply of an urban-type settlement using a heat pump

Centralized heat supply systems include a network of pipelines connecting buildings and structures in such a way that entire districts and quarters are supplied with a heat carrier from a single boiler plant. District heating is a well-studied part of the energy system. Despite this, low temperature district heating is still underdeveloped, although it is one of the key technologies for energy efficient urban heating. Low-temperature heat supply systems are the basis of 4th generation district heating systems, since they can significantly reduce heat losses during transportation of the heat carrier to the heat energy consumer and allow the use of heat from renewable sources, for example, heat pumps. The study focuses on analyzing the heat loss of a district heating system by comparing simulation results at a standard flow temperature and at a temperature typical of the 4th generation heat supply schedule. On the basis of the created model, the calculation of heat and hydraulic losses of the low-temperature district heating system was carried out, as well as a comparative analysis in comparison with the standard heat supply system.

Steady State Heat Conduction Structural Thermal Analysis of Boiler Tubes and its Design Attributed Failure

One of the important parts of the thermal power plants are tubes carrying steam generally called as boiler tubes. Any leakages in these tubes cannot be identified easily with human senses and also boiler operating condition it is impossible to investigate these tubes or leak. In order to do inspection it require shut down of the plant involving production losses. Though we do inspection with human abilities there is possibility of occurrence of error. Frequent shut downs for inspection leads to huge production loss. In recent days boiler explosions and its impact have become regular news. The intent of this paper is to identify design related failure of the boiler tubes under the thermal loading conditions. A single boiler tube is designed and its behaviour under thermal load operating conditions has been studied with the help of Ansys R15 student release simulation software. This paper gives the detailed study of the more vulnerable regions of boiler tube in design aspect.

Appropriate technology application of traditional clove oil production, effort to up-grade quality

In East Java, the production of clove leaf oil refinement is developed by businesses owned by rural people. The processing operation is simple and start-up investment is low. The clove leaf oil manufacturing procedure uses old leaves that fall naturally in the dry season, these are found to be better preserved, mature and environmentally friendly. East Java rural distillers use a single boiler for steam, water and raw materials in order for the investment costs to remain low. This study aimed to research the use of appropriate technology for the clove leaf distillation process and how to increase clove oil both in yield and quality. Two different tests were conducted; introducing a leaf crusher as a raw material and replace the old chamber material with stainless steel. There are three grades of raw materials; rough leaves, smooth leaves, and non-crushed leaves. After the clove leaves were crushed, they are distilled in the new stainless steel boiler with an aim to compare the oil yield and quality. The result from the crushed leaves treatment indicates there are different volume condensates produced from the same volume of raw materials, 128.2 litres from smooth grade and 117.2 litres from rough grade leaves. The highest percentage of clove oil (15.07%) results from rough grade crushed leaves. By replacing the chamber material with stainless steel positively affects the brightness of the clove oil. In conclusion, these two tests, to improve appropriate technology for clove oil production, can increase both yield and oil brightness, and subsequently improve the competitive advantage and future aspiration of the product.

Heating plant input–output efficiency in two cold-climate institutional buildings with condensing hot water boilers

Seasonal input–output efficiencies of two heating plants with condensing boilers in cold climate institutional buildings (3300 m2 school and 12,000 m2 university building) were evaluated. Plant efficiency remained about the same or declined with load, contrary to typical lab boiler ratings, which show efficiency increasing at lower loads. These results occurred when the boilers were operated with return water temperatures largely in the condensing range. Heating plant load was often 25% or less of the rated load of a single boiler, resulting in heating plant input–output efficiencies well below rated boiler efficiencies. Practical application: In-situ boiler plant input–output efficiencies can differ widely from manufacturer's boiler efficiency curves. For applications such as simulation for energy-efficient design, effective decision-making depends on accurately estimating real-world performance.

Prospects for using the technology of circulating fluidized bed for technically refitting Russian thermal power stations

The present state and development of circulating fluidized bed (CFB) technology around the world are briefly reviewed. Questions of increasing the capacity of single boiler units and raising the parameters of steam are discussed. CFB boilers for 225- and 330-MW power units are described and their parameters are estimated as applied to the conditions of firing different Russian fuels. Indicators characterizing CFB boilers and pulverized-coal boilers are given. Capital outlays and operational costs for new coal-fired units are compared, and the results from this comparison are used to show the field of the most promising use of the CFB technology during technical refitting of Russian thermal power stations.

The Greve in Chianti project

The power station at Greve was designed to gasify RDF pellets, and to use the resulting LEG to raise steam to drive a turbine to generate electricity. The existing plant comprises two CFBGs which operate alternately to supply LEG to a single boiler. The steam turbine operates at about 30 to 40 per cent of its nominal rating of 6.7 MW c. Although the plant has, since 1993, operated with some success, unexpected fouling of the boiler has occurred. This has caused a significant reduction in the operational availability of the power station and the resultant loss of electricity production has had a negative effect on the economics of the plant. It is proposed to install a second line, incorporating a new boiler, between one of the two existing gasifiers and the steam turbine, which will incorporate a novel combination of technologies to clean the gas produced. Fouling should therefore be reduced, increasing the operational availability of the power plant and restoring its economic viability. The implementation of the new gas clean-up system, supported by the European Commission's THERMIE Programme, will demonstrate the economic and technical viability of the production of electricity via the gasification of RDF.

Designing for Productivity: A Standardized Coal-Fired Propulsion Plant

A design for a 26 000-shp standardized coal-fired steam turbine propulsion plant using product work breakdown structure (PWBS) or group technology techniques was developed for the Maritime Administration. The purpose of the design was to provide a design package for a production approach which could reduce machinery outfitting cost and time by one third. Emphasis was placed on piping within the main machinery space. In the concept and preliminary design phases, the machinery box was developed to fit within the hull lines of an 80 000, 144 000, and 180 000-dwt collier. Propeller size, shaft line, and rpm were defined; the steam cycle was selected; and initial machinery arrangements were developed for both a dual boiler and a single boiler plant. During contract design, machinery specifications, schematic diagrams, arrangements, and procurement specifications were developed. In production design, standards were developed, schematic diagrams were revised, and piping diagrammatic arrangements, composites, material lists, and purchase orders for components were prepared. A production philosophy and build strategy also were developed. This effort made use of the PWBS approach presented in the MarAd National Shipbuilding Research Program reports[1–5]3

Design and Operation of the Ponce de Leon

A unique ship, and to some extent the transportation system of which it is a part, is described. The ship was designed to carry 250 40-ft highway trailers and about 300 automobiles in the New York to Puerto Rico trade on a weekly schedule. The ship is 700 ft long and 105 ft wide over the main deck. It displaces 24,000 tons at the design draft of 27 ft. A single boiler, steam turbine propulsion plant generates 32,000 shp driving the ship with a single screw. A controlled passive stabilization system based on the U tube tank principle is installed. Terminal facilities at both ends of the run include vehicle marshalling yards, yard tractors, scales, and loading ramps.

Engineering the Eddystone Plant for 5000-Lb 1200-Deg Steam

Abstract This paper presents a report on the problems encountered and the solutions developed in engineering a power plant with a single boiler supplying a turbogenerator set of 325,000 kw rating with throttle steam conditions of 5000 psi and 1200 F. A brief discussion is given of the co-operative method used, a short history of the supercritical pressure idea, and an abbreviated review of the significance of supercritical conditions. The paper is concerned with the problems of water conditioning and quality control, of piping materials and design requirements, of heat-cycle development, of pumping feedwater to the very high levels required, and of other miscellaneous plant-design situations. Companion papers discuss in great detail the boiler and turbine-design considerations.

Design Features, Operating Experience, and Performance of 100,000-KW Reheat Installation at Potomac River Station

Abstract It is the purpose of this paper to discuss the outstanding features, operating experience, manpower requirements, and performance record of a generating unit with a design capability of 100,000 kw and with steam conditions of 1800 psig pressure, 1050 F primary steam temperature, and 1000 F reheat steam temperature. This design capability of 100,000 kw is somewhat less than the national average of 124,000 kw for all reheat machines purchased in the last 6 years. The initial steam pressure and temperature have been surpassed by other installations, and condenser circulating-water temperature is relatively high, with maximum temperatures of 88 F and a 4-month average of 81 F for June to September, inclusive. Notwithstanding these basic limitations, the over-all thermal efficiency is averaging 37 per cent which is near optimum for conditions below the supercritical. The unit under discussion is the No. 3 unit in a station housing also two 90,000-kw non-reheat machines placed in operation in October, 1949, and June, 1950. The new No. 3 unit was placed in preliminary operation June 30, 1954, and became firm commercial capacity 2 weeks later on July 14, 1954. Unit No. 4, which is a duplicate of No. 3, is under construction and is scheduled for service early in 1956. There is a single boiler per turbine, and fuel used is pulverized coal. Light fuel oil is used for ignition.

Basic Study for a Generating Station

Abstract This paper gives the results of cost studies made to determine the most economical size and type of boiler and turbogenerator unit to be used in a new generating station for the Consolidated Edison Company of New York, Incorporated. Some of the factors considered include the economical capacity of the unit; single boiler versus two boilers per turbine; unit-type design versus a common steam-header system and reheat versus nonreheat units. Related factors were the number and type of feedwater heaters and alternate arrangements of boiler feed pumps.

Some Engineering Features of the Weymouth Station of The Edison Electric Illuminating Co. of Boston

The new power station of The Edison Electric Illuminating Company of Boston, now under construction on the Weymouth Fore River is expected to have an ultimate capacity of about 300,000 kw. The present construction covers the installation of two 32,000 kw. generating units with three 1974-h. p. boilers, operating at 375 lb. steam pressure and 700 deg. fahr. In addition, a single boiler to carry steam at pressures up to 1200 lb. is to be installed. This boiler will have about the same heating surface as the normal pressure boilers. The steam generated by it will pass through a pressure reducing turbine developing about 2000 kw., and will be exhausted at 375 lb. pressure. After being reheated to the original temperature of 700 deg. the steam will be piped to the main header and used in the large turbines. If satisfactory results are obtained from the higher-pressure boilerturbine units more of them will be installed. Three will be required to furnish sufficient steam to operate one of the 32,000-kw. units. The maximum steam temperature was fixed at 700 deg. in consideration of the properties of materials at the higher temperatures. While the theoretical gain from higher pressure increases up to the maximum for which any data are available, the full benefit of the thermodynamic possibilities are not at present obtainable in practise without reheating the steam at some point intermediate between the throttle and the condenser.

Some Factors in Fuel Economy in Boiler Plants

Abstract According to the author’s estimates, it should be easily possible to increase the combined boiler and furnace efficiency of stationary plants burning bituminous coal from 12 to 15 per cent above that ordinarily obtained. Conditions regarding character of fuel, design of furnace and grates, facilities for introducing air, draft, etc., are accordingly stated, compliance with which should substantially effect the savings mentioned in the case of a single boiler. The case of several boilers combined for service is also considered, and the author outlines a novel scheme of operation and points out the advantages it possesses over the ordinary method of running.