Optimization for Biogas Power Plants using Automatic Control of Gas Pressures
In many cases, gas storages on biogas power plants are not used optimally to store gas as much as their capacity. The digester is sometimes overload to store gas and the controller cannot deliver gas to other storage. Consequently, gas is often released from digester to avoid over pressure. At the end, biogas power plant has less efficiency. Hence, a mechanism to control gas pressure to make different pressure between its storages is required. Fans were used to manipulate the most majority system pressures on a biogas power plant using frequency converters. Measurements, simulations, and experiments were conducted to create a new system on a biogas power plant. A controller, Programmable Logic Controller was used to control the entire system pressure using Proportional-Integral-Derivative algorithm. When the gas pressures are not in the allowable range of pressure, then the controller changes the fans’ frequency to the desired conditions. As a result, gas moves to another storage and system pressures are in the allowable range.
Design of PLC-based Smith Predictor for Controlling Processes with Long Dead Time
process model and a pure dead time element. The process model represents a first order plus dead time – FOPDT approximation of the actual process dynamics. Many technological processes can be approximated reasonably accurately with a FOPDT dynamic model. Even if the process to be controlled is not first order in its nature a FOPDT Smith predictor still can be used to provide better loop response. Advanced control structures are seldom used in processes controlled by a single PLC. Significant improvements can be made in the quality of the final products in manufacturing by reducing process performance variability.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.