Impact of Thermal Asymmetry on Efficiency of the Heat Recovery and Ways of Restoring Symmetry in the Flow Reversal Reactors

Abstract

Abstract The problem discussed in the paper was revealed during experimental and simulation study of the waste fuel utilization (low concentrated CH4) which in coal mines is emitted to the atmosphere as the so-called ventilation air methane (abbreviation: VAM). When an intense heat recovery would be applied to the Reverse-Flow Reactor (RFR) then the reactor becomes susceptible to creation of temperature profiles asymmetry. This may adversely affects the heat recovery efficiency. When a strong asymmetry arises, it can significantly reduce the heat recovery and the system needs immediate counteraction. Commonly used control systems do not always cope with this problem. The paper discusses various RFRs control algorithms from the point of view of the ability to reduce symmetry to the acceptable range. The impact of the loss of reactor symmetry on possible heat recovery efficiency is also briefly discussed. The work is focused on RFRs which operate with significant heat recovery in a heat exchange unit in which heat is retrieved not at the rector outlet, but by cooling the hot gas from the center part of the reactor. Issues discussed in the paper are derived from being carried out in ICE-PAS through many years of simulation research, patent examinations, but primarily from the own experiences on the research & demonstration thermal flow reversal reactor (TFRR) for VAM combustion. Computer control & data recording system process data records of the experiments enabled effectively analyze the problem of creating and preventing thermal asymmetry.