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APCS OF SECTION-TYPE FURNACES

Automatic process control system of pipes tempering in section-type furnaces No.1, 2 in furnace zone Tube Rolling Shop 4 at NTRP OJSC.

Production facility description

The furnace is divided into four zones and 20 sections, 5 sections for zone. Pipes move on roller track inside of furnace with a preset speed. The furnace is heated with natural gas. After 20-th section, pipes tempering is performed with service water in sprayer.

Purpose and functions of ACS
Automatic process control system (APCS) of solid-rolled pipes tempering in section-type furnaces in furnace zone of Tube Rolling Shop 4 is intended for selection and maintenance of optimal pipes heating and tempering mode depending on pipes range and chemical composition of steel, and for quick notification of operating personnel of process modes and archivation of technological and energy consumption data.

Automatic control system of section-type furnaces in tube rolling shop is represented by two hardware and software complexes for automation of the whole production process of pipes heating, each of which consists of:

• field control equipment (flow, pressure sensors, pyrometers SIEMENS),
• master controller - SIMATIC S7-300 programmable controller,
• standby controller - IM CPU on basis of ET 200S (hot standby),
• main PC-based automated working station (at customer's option IL – 70 is possible),
• small emergency operator's panel ОР-3,
• central operator's panel, one for two furnaces.

The system has the following capabilities:

• pipes temperature measurement on exit from the furnace;
• pipes temperature measurement after 8 and 14 sections;
• entry and processing of group properties, such as batch number, cast number, range showings;
• on-line computation and generation of optimal temperature settings (by criterion of power consumption minimization at preset output temperature parameters of blank parts) in furnace zones based on thermophysical process model;
• on-line control of temperature in furnace zones, air-gas ratio with compensation by oxygen content in combustion gas, furnace pressure;
• general air pressure (by method of frequency regulation of pressure fans drives);
• on-line temperature control in furnace zones in non-steady processes, arising in case of change of furnaces operating mode;
• process visualization, execution of report forms and flow and temperature register;
• recording of gas flow by shifts, days, months, quarters;
• emergency mode protection, autodiagnostics and testing;
• possibility of maximum - minimum gas flow limitation by zones with preset values, entered in screen forms, which obtains special relevance in connection with rising prices of energy resources;
• regulator setting in screen forms by competent personnel (password protected option);
• events history in the form of diagrams, enables to observe quickly whatever took place in the furnace during two days;
• calculation of specific energy consumption per ton of products by ranges and casts – enables to analyze cost-efficiency of production in terms of energy consumption;
• recipes and operating modes system - “run”, “standby”, “empty furnace” - enable to select the required furnace operating mode in one-touch.

The system is certified by State Dnepropetrovsk verification center.

ACS functional layout

Results and adaptation effect
Due to using modern automation equipment and new technical solutions we succeeded to achieve stability of process modes - temperature differential in zones max 2°С.
Gas saving after adaptation made from 10%.