It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a ...It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.展开更多
This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant litera...This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows： 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are： the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as： impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three展开更多
The transient heat transfer between working fluid and inner wall of 600 MW supercritical pressureboiler's water separator model during start-up was experimentally explored. The test conditions forwater steam two-p...The transient heat transfer between working fluid and inner wall of 600 MW supercritical pressureboiler's water separator model during start-up was experimentally explored. The test conditions forwater steam two-phase were as follows: pressure P = 3 ~ 11 MPa, mass now M = 0.2 ~ 0.35 kg/s,and mass quality x = O.2 ~ 0.8; for subcooled water P = 3 ~ 11 MPa, M = 0.2 ~ 0.35 kg/s, andsubcooled degree △θ = 10℃. By using an accurate and tractable inverse heat conduction solution,the correlations of single phase and twouphase transient heat transfer coefficients were obtained. Theexperimental results demonstrated the heat transfer enhanced for subcooled water and water steammixture compared with fully developed turbulent flow in tube. The increasing heat transfer effect maybe attributed to the deformation or destruction f the boundary layer.展开更多
文摘It is presented that a feasibility assessment of solar preheating of steam boiler feed water for opened vapor systems. Data from a medium sized dairy industry near Rio de Janeiro city, in Brazil, is used to compose a case study. Forty eight solar heating system computer simulations were carried out in TRNSYS （transient system simulation software）, for a range of design parameters corresponding to the 5% best economic results of a series of 2,700 simpler simulations （φ,f-chart method）, programmed on Matlab. It has been used TMY （typical meteorological year） hourly weather data from Rio de Janeiro. Investment cost was composed from both commercial and literature values, while revenue was based on the avoided consumption of fuel for LPG （liquefied petroleum gas）, natural gas and fuel oil, with only the first showing economically feasible. The results, however, made it possible to address environmentally sound public policies to encourage industrial solar energy use.
文摘This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows： 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are： the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as： impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three
文摘The transient heat transfer between working fluid and inner wall of 600 MW supercritical pressureboiler's water separator model during start-up was experimentally explored. The test conditions forwater steam two-phase were as follows: pressure P = 3 ~ 11 MPa, mass now M = 0.2 ~ 0.35 kg/s,and mass quality x = O.2 ~ 0.8; for subcooled water P = 3 ~ 11 MPa, M = 0.2 ~ 0.35 kg/s, andsubcooled degree △θ = 10℃. By using an accurate and tractable inverse heat conduction solution,the correlations of single phase and twouphase transient heat transfer coefficients were obtained. Theexperimental results demonstrated the heat transfer enhanced for subcooled water and water steammixture compared with fully developed turbulent flow in tube. The increasing heat transfer effect maybe attributed to the deformation or destruction f the boundary layer.
