In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial l...In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial losses, or in the pharmaceutical industry, it can result in an unusable batch. In these industries, batch reactors are commonly used, the control of which is essentially a problem of temperature control. In the industry, an increasing number of heating-cooling systems utilising three different temperature levels can be found, which are advantageous from an economic point of view. However, it makes the control more complicated. This paper presents a split-range designing technique using the model of the controlled system with the aim to design a split-range algorithm more specific to the actual sys- tem. The algorithm described provides high control performance when using it with classical PID-based cascade temperature control of jacketed batch reactors;however, it can be used with or as part of other types of controllers, for ex- ample, model-based temperature controllers. The algorithm can be used in the case of systems where only two as well as where three temperature levels are used for temperature control. Besides the switching between the modes of opera- tion and calculating the value of the manipulated variable, one of the most important functions of the split-range algo- rithm is to keep the sign of the gain of the controlled system unchanged. However, with a more system-specific split-range solution, not only can the sign of the gain be kept unchanged, but the gain can also be constant or less de- pendent on the state of the system. Using this solution, the design of the PID controller becomes simpler and can be implemented in existing systems without serious changes.展开更多
Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce ene...Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter.In this paper,first principle-based model of variable volume microbial fuel cell is simulated.Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses.Classical PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo problem.Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set point.These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells.The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel cell.Also,there is no increase in the working volume of the constant volume microbial fuel cell.Hence,operating range of the microbial fuel cell is enhanced using split range controller.展开更多
文摘In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial losses, or in the pharmaceutical industry, it can result in an unusable batch. In these industries, batch reactors are commonly used, the control of which is essentially a problem of temperature control. In the industry, an increasing number of heating-cooling systems utilising three different temperature levels can be found, which are advantageous from an economic point of view. However, it makes the control more complicated. This paper presents a split-range designing technique using the model of the controlled system with the aim to design a split-range algorithm more specific to the actual sys- tem. The algorithm described provides high control performance when using it with classical PID-based cascade temperature control of jacketed batch reactors;however, it can be used with or as part of other types of controllers, for ex- ample, model-based temperature controllers. The algorithm can be used in the case of systems where only two as well as where three temperature levels are used for temperature control. Besides the switching between the modes of opera- tion and calculating the value of the manipulated variable, one of the most important functions of the split-range algo- rithm is to keep the sign of the gain of the controlled system unchanged. However, with a more system-specific split-range solution, not only can the sign of the gain be kept unchanged, but the gain can also be constant or less de- pendent on the state of the system. Using this solution, the design of the PID controller becomes simpler and can be implemented in existing systems without serious changes.
文摘Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter.In this paper,first principle-based model of variable volume microbial fuel cell is simulated.Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses.Classical PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo problem.Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set point.These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells.The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel cell.Also,there is no increase in the working volume of the constant volume microbial fuel cell.Hence,operating range of the microbial fuel cell is enhanced using split range controller.
