A new proposal of a centralized configuration for a multilevel pressure network: A real time controller in closed loop

A compressed air system feeds several end-users, each of them requiring air at a proper pressure; from an energy saving point of view, the network should work at the lowest functional pressure that meets production requirements. When different working pressures occur in the same plant, a rank of the final end-user, based on their operating pressure, is necessary; for each of the identified end-user macro-group, a decentralized set of compressors could be designed, thus involving higher installation and maintenance costs. This paper introduces to a new configuration in the compressed air production, when several operative pressures exist. The new network layout deals with a single compressor, fixed speed-electrically driven, and a centralized type of production, alternative to and more efficient of a decentralized one. A closed loop control method for a radial multilevel pressure air network is presented. Using a multilevel pressure compressor, instead of n independent smaller compressors, it is possible to provide air to different networks, by properly operated valves on the compressor. A set of suitably controlled valves intercepts air at the desired pressure level and feeds the networks while their operation guarantees that each pressure level is kept inside safe ranges. The centralized compressed air production is made possible by inheriting the real time scheduling theory: the idea is to state how to design a valves opening and closing sequence, delivering the required air amount to end-users, guaranteeing, at the same time, a proper pressure level inside each of the systems. In this way, higher efficiencies of bigger machines can be better exploited for the sake of energy saving. A theoretical case study with three different networks, operating in the range of 0.75, 1.0 and 1.3 MPa_g is proposed. The following proposal integrates a previous work, besides, future developments are also anticipated.