As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introd...As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.展开更多
A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal powe...A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal power plants. The P1-P2 method is used in the present study, together with the thermoeconomic analyses of feed water heaters.展开更多
The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time de...The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.展开更多
This study assessed the fish production, culture facilities, operations, water resource management and profitability of fish farming in Katsina State, Nigeria, with a view of understanding the status of aquaculture de...This study assessed the fish production, culture facilities, operations, water resource management and profitability of fish farming in Katsina State, Nigeria, with a view of understanding the status of aquaculture development in Katsina State. Data were collected using structured questionnaire administered to 35 out of the active 42 farms in Katsina State at the period and the data obtained were analyzed using descriptive statistics and linear regression. Among the respondents, 37.1% used concrete tank alone and another 37.2% used concrete tank with other types of culture facilities, 57.1% practised mono-culture techniques and 77.1% used stagnant renewal system as culture system. Management of water quality was done by majority(82.9%) with mere visual evaluation, while 68.6% did not use any forms of water treatment. Most of the farms(80%) depended on imported feed for feeding their fish and gross profits of ■7.29±1.81 and ■157.83±118.08 were obtained on fingerlings and adult fish, respectively. The tested explanatory variables were responsible for 45.4% change in profitability and profitability was found to be dependent on feeding cost(t=–3.38 and p=0.002) and size of fish at harvest(t=2.70 and p=0.011). The research findings established that fish farming in Katsina State was under developed.展开更多
An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then direct...An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the cham- ber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recog- nized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi- phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.展开更多
目前社会电力资源的需求量不断提升,对于火力发电厂提出了更高的要求.现阶段,分散控制系统(Distributed Control System,DCS)已经成为一种至关重要的自动化远程控制系统,将其有效应用在火力发电厂的给水控制过程中,能够稳步提升整体系...目前社会电力资源的需求量不断提升,对于火力发电厂提出了更高的要求.现阶段,分散控制系统(Distributed Control System,DCS)已经成为一种至关重要的自动化远程控制系统,将其有效应用在火力发电厂的给水控制过程中,能够稳步提升整体系统的安全性与稳定性,满足火力发电厂的基本工作需求.论述了DCS分散控制系统概念的,分析DCS分散控制系统在火力发电厂给水控制中的应用.展开更多
文摘As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.
文摘A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal power plants. The P1-P2 method is used in the present study, together with the thermoeconomic analyses of feed water heaters.
文摘The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.
文摘This study assessed the fish production, culture facilities, operations, water resource management and profitability of fish farming in Katsina State, Nigeria, with a view of understanding the status of aquaculture development in Katsina State. Data were collected using structured questionnaire administered to 35 out of the active 42 farms in Katsina State at the period and the data obtained were analyzed using descriptive statistics and linear regression. Among the respondents, 37.1% used concrete tank alone and another 37.2% used concrete tank with other types of culture facilities, 57.1% practised mono-culture techniques and 77.1% used stagnant renewal system as culture system. Management of water quality was done by majority(82.9%) with mere visual evaluation, while 68.6% did not use any forms of water treatment. Most of the farms(80%) depended on imported feed for feeding their fish and gross profits of ■7.29±1.81 and ■157.83±118.08 were obtained on fingerlings and adult fish, respectively. The tested explanatory variables were responsible for 45.4% change in profitability and profitability was found to be dependent on feeding cost(t=–3.38 and p=0.002) and size of fish at harvest(t=2.70 and p=0.011). The research findings established that fish farming in Katsina State was under developed.
基金supported by the National Innovate Research Groups Foundation of China (50621403)National Basic Research Program of China (2009CB724600).
文摘An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the cham- ber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recog- nized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi- phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.
文摘目前社会电力资源的需求量不断提升,对于火力发电厂提出了更高的要求.现阶段,分散控制系统(Distributed Control System,DCS)已经成为一种至关重要的自动化远程控制系统,将其有效应用在火力发电厂的给水控制过程中,能够稳步提升整体系统的安全性与稳定性,满足火力发电厂的基本工作需求.论述了DCS分散控制系统概念的,分析DCS分散控制系统在火力发电厂给水控制中的应用.
