Search results

The purpose of this paper is to deal with the performance modeling and assessment of maintenance priorities for steam generation unit of a sugar plant.

The unit comprises of four subsystems, i.e., Bagasse elevator, Bagasse carrier, boiler and feed pump. The Chapman–Kolmogorov equations are generated on the basis of transition diagram and further solved recursively to obtain the performance modeling with the help of normalizing condition using the Markov approach.

Decision matrices are formed with the help of different combinations of failure and repair rates of all subsystems. The performance of steam generation unit is evaluated in terms of availability levels depicted in decision matrices and plots of failure rates and repair rates of various subsystems. The maintenance priorities of various subsystems of steam generation unit are decided on the basis of effect of failure and repair rates of subsystems on the availability of steam generation unit. The key finding is that the boiler subsystem is the most critical subsystem and hence should be kept on top maintenance priority for performance enhancement of the steam generation unit.

The acceptance of both performance modeling and maintenance priorities decision by the management of sugar plant will result in the enhancement of unit availability and reduction of maintenance cost.

The purpose of this paper is to present a method for monitoring transient thermal stresses. This paper also presents the analysis of thermal stresses of boiler pressure element heating during the start-up in real conditions. The inverse methods are used to determine the wall temperature, whereas the commercial software ANSYS is used to determine the thermal stresses in the pressure component.

The method is based on the solution of the inverse heat conduction problem. Thermal stresses are determined indirectly taking into account the measured temperature values at selected points on the outer wall of a pressure component. First, the transient temperature distribution in the entire pressure element is calculated, and then, thermal stresses are determined by the finite element method. Measured pressure changes are used to determine the stresses resultant from the internal pressure.

The obtained stresses and temperature in the thick-walled pipe are illustrated and compared with experimental data. Satisfactory agreement was found between computational and experimental results.

The method can be used in the monitoring of thermal and mechanical stresses during the boiler’s start-up and shut-down. Because the temperature distribution at each time level is determined, it can be applied as a thermal load during the structural analysis.

An effective chemical conditioning technique was successfully tested and investigated to control and minimize the chemistry-related damages within mixed metallurgy steam and water cycle of Heller dry cooled combined cycle power plants (CCPPs), in which cooling water and condensate are completely mixed in direct contact condenser. This study aims to perform a comprehensive experimental research in four mixed metallurgy steam and water cycle.

A comprehensive experimental study was carried out in four mixed metallurgy steam and water cycle fabricated with ferrous- and aluminum-based alloys which have various corrosion resistance capabilities in contact with water. Chemical conditioning was conducted using both volatile and non-volatile alkalizing agents, and, to perform chemical conditioning effectively, quality parameters (pH, conductivity, dissolved oxygen, sodium, silica, iron, aluminum and phosphate) were monitored by analyzing grab and online samples taken at eight key sampling points.

Results indicated that pH was the most critical parameter which was not mainly within the recommended ranges of widely used standards and guidelines at all key sampling points that generally increases the occurrence of chemistry-related damages. The other quality parameters were mostly satisfactory.

In this research, the development of a suitable chemical conditioning technique in mixed metallurgy steam and water cycle, fabricated with ferrous and aluminum-based alloys, was studied. The obtained results in this thorough research work was evaluated by comparison with the chemistry limits of the widely used standards and guidelines, and combined use of volatile and solid alkalizing agents was considered as a promising chemical conditioning technique for utilization in mixed metallurgy units of Heller dry cooled CCPPs.

Steam contamination (solid particles in the superheated steam) comes from the boiler water largely in the carry‐over of water droplets. The need for extreme purity of steam for use in high pressure turbines has prompted the development of highly satisfactory devices for separating steam and water in a boiler drum. Consequently, steam contamination has been steadily reduced. Troublesome turbine blade deposits may occur with surprisingly low (0.6 ppm) total solids contamination in steam. In the 3.5–6 MPa range, however these deposits are usually water soluble and can be removed by periodic washing. In the 4 to 10 MPa range, however, silica deposits predominate and these deposits are not easily removed by water washing. With operating pressure of 13 MPa and above insoluble deposits do occur which may be controlled by residual water washing. Before the unit is returned to service, the deposits should be removed by air or water‐driven turbine cleaners or by chemical cleaning.

This paper aims to reveal how different types of events and top management teams' (TMTs’) cognitive frames affect the generation of breakthrough innovations.

Drawing on the event system theory and upper echelon theory, this study chose a Chinese manufacturing enterprise as the case firm and conducted an exploratory single-case study to unpack how breakthrough innovation generates over time.

By conducting the in-depth case analysis, the study revealed that firms do not produce breakthrough innovation in the catch-up stage and parallel-running stage but achieve it in the leading stage. It also indicated that when facing proactive events in the catch-up stage, TMTs often adopt a contracted lens, being manifested as consistency orientation, less elastic organizational identity and narrower competitive boundaries. In addition, they tend to adopt a contracted lens when facing reactive and proactive events in the parallel-running stage. In the face of reactive and proactive events in the leading stage, they are more inclined to adopt an expanded lens, being manifested as a coexistence orientation, more elastic organizational identity and wider competitive boundaries.

First, by untangling how TMT's cognitive frame functions in breakthrough innovations, this paper provides a micro-foundation for producing breakthrough innovations and deepens the understanding of upper echelon theory by considering the cognitive dimension of TMTs. Second, by teasing out several typical events experienced by the firm, this paper is the first attempt to reveal how events affect the generation of breakthrough innovation. Third, the work extends the application of the event system theory in technological innovation. It also provides insightful implications for promoting breakthrough innovations by considering the role of proactive and reactive events a firm experiences and TMT's perceptions.

Improved nuclear reactor configurations that address major concerns of environmentalists and safety analysts are discussed. In addition to social acceptance, these new modes of power generation have economic potential to become the dominant producers of energy in the twenty‐first century. The class of power generation with this promise is the high temperature gas reactor (HTGR); the variant we focus on is the pebble‐bed modular reactor (PBMR). We also focus on using nuclear power as an energy source for desalinating seawater. Finally, the case is made that HTGR reactors are ideal for supplying the high‐temperature heat needed for manufacturing molecular hydrogen, a leading candidate for clean fuel consumption. These three themes are developed in a broad context with the objective of recommending policy actions dealing with global warming, public health, and economic opportunity.

This paper aims to broaden the conversation regarding STEAM by investigating the new form of education. The novelty of science, technology, engineering, art and mathematics (STEAM) instruction in K-12 classrooms means few cases of STEAM teaching are documented in depth.

As part of a larger multi-year study researching STEAM teaching practices in 14 middle school classrooms in the southeastern USA, the article first summarizes prior research findings and then presents ideas for higher education and K-12 researchers to consider when incorporating STEAM teaching in pre-service education, professional development and in classrooms. Then, the authors use a second-order narrative approach to describe three cases of teachers enacting STEAM practices in classrooms.

Drawing on the notion of “remixing” education in the context of STEAM, the authors show how each teacher alters existing practices, instead of offering entirely new instruction, as they implement STEAM teaching.

With few cases of STEAM teaching detailed in the depth, this paper advances the understanding of STEAM teaching practices in K-12 classrooms.

THE TOTAL ENERGY PLANT located by Trans World Airline at their overhaul base at Kansas City International Airport is unique in that the prime movers for power generation are Pratt & Whitney JT4 flight engines. The plant serves the 1,200,000 sq ft airframe and engine overhaul facility, the new 500,000 sq ft superhangar for servicing 747's and L1011's, the new 500,000 sq ft administrative office building, and the new flight training centre, as well as several other smaller buildings. This is TWA's main overhaul and administrative centre for the airline.

The purpose of this paper is to assess the carbon dioxide emissions associated with electric, HVAC, and hot water use from a US university.

First, the total on‐campus electrical, natural gas and oil consumption for an entire year was assessed. For each category of energy use, the carbon associated with consumption of a single unit was calculated. Using this, the total carbon dioxide emissions for the entire university were estimated.

It was found that the university's activities resulted in approximately 4 tons of carbon dioxide emissions per student per year. In total, the university emitted nearly 38,000 tons of carbon dioxide during the 2007 fiscal year. In addition, it was found that emissions from on‐campus steam production, which account for roughly 57 per cent of total CO₂ emissions, would be improved with the addition of two proposed cogeneration facilities.

The originality and value of this paper is attributed to: the recent international concern over CO₂ emissions and their global warming impact; the increasing adoption of the American College & University Presidents' Climate Commitment which in part calls for an inventory of campus emissions; and the underdeveloped research area relating to total university campus carbon footprint estimation.

The paper aims to design and prove the concept of micro-industry using trigeneration fuelled by biomass, for sustainable development in rural NW India.

This is being tested at village Malunga, near Jodhpur in Rajasthan. The system components comprise burning of waste biomass for steam generation and its use for power generation, cooling system for fruit ripening and the use of steam for producing distilled water. Site was selected taking into account the local economic and social needs, biomass resources available from agricultural activities, and the presence of a NGO which is competent to facilitate running of the enterprise. The trigeneration system was designed to integrate off-the-shelf equipment for power generation using boilers of approximate total capacity 1 tonne of fuel per hour, and a back-pressure steam turbo-generator (200 kW). Cooling is provided by a vapour absorption machine (VAM).

The financial analysis indicates a payback time of less than two years. Nevertheless, this is sensitive to market fluctuations and availabilities of raw materials.

Although comparable trigeneration systems already exist in large food processing industries and in space heating and cooling applications, they have not previously been used for rural micro-industry. The small-scale (1-2 m3/h output) multiple effect distillation (3 effect plus condenser) unit has not previously been deployed at field level.