REVISED CONTROL-SYSTEM FOR A SEMICONTINUOUS FLOWING-SOLVENT LIQUEFACTION REACTOR

An integrated control and measurement system based on a single host computer (PC) has been constructed for running a semi-continuous flowing-solvent coal liquefaction reactor. The system, composed of a mix of special circuits and commercially available units, provides accurate temperature and flow control, data acquisition, real time display, and safety interlock. The real-time job-conflict problems are solved by using the interrupt concept: the background basic feedback control loop working in external interrupt mode took priority, with a foreground service routine executing more time-consuming tasks, including data recording to disk, and real-time result display on screen. Improved computer reliability, ease of maintenance, increased flexibility in the design of individual experiments, suppression of temperature overshoots and closer control of the solvent flow rate, have all served to improve the quality of data required for evaluating kinetic parameters. The design is readily adaptable to experiments requiring temperature and flow (or other variable) control, data acquisition, real-time results display, and safety interlock (fail-safe) functions. (C) 1995 American Institute of Physics.