Parallel turbine-driven feedwater pumps are needed when ships travel at high speed. In order to study marine steam generator feedwater control systems which use parallel turbine-driven feed pumps, a mathematical model...Parallel turbine-driven feedwater pumps are needed when ships travel at high speed. In order to study marine steam generator feedwater control systems which use parallel turbine-driven feed pumps, a mathematical model of marine steam generator feedwater control system was developed which includes mathematical models of two steam generators and parallel turbine-driven feed pumps as well as mathematical models of feedwater pipes and feed regulating valves. The operating condition points of the parallel ttu-bine-driven feed pumps were calculated by the Chebyshev curve fit method. A water level controller for the steam generator and a rotary speed controller for the turbine-driven feed pumps were also included in the model. The accuracy of the mathematical models and their controllers was verified by comparing their results with those from a simulator.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
Interfacial solar-steam generation is a promising and cost-effective technology for both desalination and wastewater treatment.This process uses a photothermal evaporator to absorb sunlight and convert it into heat fo...Interfacial solar-steam generation is a promising and cost-effective technology for both desalination and wastewater treatment.This process uses a photothermal evaporator to absorb sunlight and convert it into heat for water evaporation.However solar-steam generation can be somewhat inefficient due to energy losses via conduction,convection and radiation.Thus,efficient energy management is crucial for optimizing the performance of solar-steam generation.Here,via elaborate design of the configuration of photothermal materials,as well as warm and cold evaporation surfaces,performance in solar evaporation was significantly enhanced.This was achieved via a simultaneous reduction in energy loss with a net increase in energy gain from the environment,and recycling of the latent heat released from vapor condensation,diffusive reflectance,thermal radiation and convection from the evaporation surface.Overall,by using the new strategy,an evaporation rate of 2.94 kg m^-2 h^-1,with a corresponding energy efficiency of solar-steam generation beyond theoretical limit was achieved.展开更多
文摘Parallel turbine-driven feedwater pumps are needed when ships travel at high speed. In order to study marine steam generator feedwater control systems which use parallel turbine-driven feed pumps, a mathematical model of marine steam generator feedwater control system was developed which includes mathematical models of two steam generators and parallel turbine-driven feed pumps as well as mathematical models of feedwater pipes and feed regulating valves. The operating condition points of the parallel ttu-bine-driven feed pumps were calculated by the Chebyshev curve fit method. A water level controller for the steam generator and a rotary speed controller for the turbine-driven feed pumps were also included in the model. The accuracy of the mathematical models and their controllers was verified by comparing their results with those from a simulator.
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
基金financial support from Australian Research Council(ARC Future Fellowship FT190100485)University of South Australia(Foundation Fellow)China Scholarship Council and Huasheng Graphite Co.,Ltd。
文摘Interfacial solar-steam generation is a promising and cost-effective technology for both desalination and wastewater treatment.This process uses a photothermal evaporator to absorb sunlight and convert it into heat for water evaporation.However solar-steam generation can be somewhat inefficient due to energy losses via conduction,convection and radiation.Thus,efficient energy management is crucial for optimizing the performance of solar-steam generation.Here,via elaborate design of the configuration of photothermal materials,as well as warm and cold evaporation surfaces,performance in solar evaporation was significantly enhanced.This was achieved via a simultaneous reduction in energy loss with a net increase in energy gain from the environment,and recycling of the latent heat released from vapor condensation,diffusive reflectance,thermal radiation and convection from the evaporation surface.Overall,by using the new strategy,an evaporation rate of 2.94 kg m^-2 h^-1,with a corresponding energy efficiency of solar-steam generation beyond theoretical limit was achieved.
