Simulating continuous furnace conditions in a batch furnace was a new furnace concept undertaken by Harper International Corp. (Lancaster, N.Y.) in a pilot project that also involved BCS/Sanwal (Tonawanda, N.Y.) and Eurotherm Process Automation. The actual process is proprietary, but the end user wanted to simulate different furnace conditions to establish the aspects of a continuous furnace. Harper built and automated a batch furnace for the customer that simulated a continuous multizone, multisection production furnace. The furnace is capable of achieving very high temperatures in a very short time. The process had to have the capability of changing various physical components and tuning parameters, together with temperature, gas flow and atmosphere composition as needed, which required a versatile, flexible control system. The customer wanted the furnace system controller to have a programmable setpoint with the ability to hold, or "freeze," at any given time, or to hold and then go to a predefined level when certain atmospheric circumstances occurred. The customer also wanted to be able to log data from the batch to a local floppy disc with the ability to incrementally change the file of each batch automatically.
The complexity of control was facilitated using the high-level programming tools and the high level of integration provided by Eurotherm's T800 Visual Supervisor and 2500 I/O. The powerful videographic control system has the capability of a multiloop process controller, data logger, setpoint programmer and has its control algorithms embedded in an HMI touch screen.