The use of a lining made of ceramic-fiber refractories and low-inertia heat-insulating materials is effective in terms
of both cost and reliability under the existing production conditions. Here, temperatures in the furnace might reach 900°C but
the temperature of the outside surfaces climbs no higher than 45°C. There is also a sharp reduction in construction costs, a
reduction in the costs associated with furnace ignition and startup by a factor of 3–5, and a several-fold decrease in the costs
connected with the accumulation of heat. The furnace has been operating for more than two years and no problems have
developed with the lining.
The automatic control system (ACS) that regulates pulsed heating in the furnace was certified for use and later
improved significantly [5–7]. The ACS is based on programmable logic controller (PLC) S7-3142DP made by Siemens. The
system used to monitor the process is based on the WinCC SCADA-system, and GSM technology is used to adjust and control
the heating process, including remotely.
The PLC acts as a PID regulator for each furnace zone and pulse converter. In addition to performing its main control
functions, the PLC executes auxiliary tasks – monitoring the velocity of the gases leaving the furnace, acting as an interlock
for safety purposes, etc. The thermal load is regulated by changing the duration of the pulses when the period is constant
(PLD-modulation). In this case, the system employs a unique algorithm to convert the set points of the regulator into a train of
pulses. This makes it possible to minimize the number of sudden changes in temperature and pressure inside the furnace.
In addition to providing a system that directly automates the heating of the furnace, designers developed a monitoring
and control system based on the Siemens WinCC v4.02 SCADA-system for microcomputers (MC, Fig. 3). The MC
receives data from the controller in real time and stores them on a hard drive for subsequent analysis. The use of such a
scheme makes it possible to avoid direct human intervention in the data collection process and makes it unnecessary for the
process engineer to constantly be in the shop building near the furnace while it is operating. The installation of the MC in a
building that is apart from the shop’s main building makes working conditions more comfortable for the engineer.
As noted above, the designers developed a system that allows for remote adjustment and control of the heating process.
Remote control is an important and defining element of modern automated systems used to control production processes
and is the largely result of the growth of corporate networks at production facilities. These networks make it possible to transmit
large volumes of data within an acceptable period of time. Also, given the wide range of furnace technologies currently
in use, remote control makes it possible to develop and refine control algorithms working in the office. The servicing of specialized
equipment such as the Siemens PLC requires the use of highly qualified specialists who have completed a course targeted
specifically for such a job. However, remote control of the process solves the problem of having to quickly locate faults
in equipment, and it even makes it possible to have the system rebooted by personnel who are not fully trained.