Increase in oxygen blast pressure of smelting is among the main ways to achieve higher productivity of blast furnaces, reduce use of coke and enhance quality of metal. High pressure results in higher speed of blast inside the furnace; thus leading to the
BLESSED BLAST FURNACE
BLESSED BLAST FURNACE
New technologies as a priority development for
Ukraine’s mining & metal
Increase in oxygen blast pressure of smelting is among the
main ways to achieve higher productivity of blast furnaces, reduce use of coke and enhance
quality of metal. High pressure results in higher speed of blast inside the furnace; thus
leading to the ascending oxygen causing greater resistance to the descending materials
smelted.
Soviet and US metallurgists have been working on the issue
of pressure ever since 1940s-1950s. The USSR chose a way of manufacturing more powerful
turbo-compressor units (TCU) and steam turbine or electric drives for them. Parallel and
series connection of TCUs was also made use of widely. Owing to that, blowers consumed
much more energy. Additionally, this set yet another optimisation task, namely, accurate
sustenance of pressure underneath the fire bar under condition of alternating interaction
of counter currents in the blast furnace stack and minimal use of energy to power the TCU.
However, the methods applied today consume much energy, are
obsolete, fail to provide appropriate accuracy and place high reliance on personnel
skills. The existing TCU automatic control systems are also out-of-date; thus hampering
effective and efficient blowing processes. Above all, they fail to provide accurate,
effective and efficient prevention of TCU surge that results in malfunctions of TCU mode
and blast furnace processes and might cause accidents.
Krivorozhstal State Mining and Iron & Steel Works is
the first in Ukraine and CIS to introduce a modern microprocessor-based TCU Automatic
Control System 5500. Vladimir Sheremet, technical director of the integrated mill, and
Oleg Dubina, director general of Krivorozhstal, supported the idea proposed by chief
engineer Anatoly Shvets in 1999. Out of all available proposals of domestic and foreign
companies, Krivorozhstal has selected US Compressor Controls Corporation (CCC) that
submitted the most acceptable proposal in terms of cost, efficiency and adaptability to
worn-out metalmaking equipment. The CCC System is a modern microprocessor-based
electro-hydraulic control system that enhances effectiveness, efficiency and reliability
of TCUs and blast furnaces. The system comprises a programming & technical module and
digital-control electromechanical transducers.
Application of the CCC System has already yielded
favourable result, notably:
accurate sustenance of a particular rotation frequency of the compressor
rotor (with error of about 1 revolution per minute);
TCU’s functioning with sealed CHOPT valves and blow-off valve;
lower loss of oxygen blast;
sustenance of pressure to the accuracy of 0.01 bar;
effective protection of compressor against surge and, consequently,
compressor’s operation in direct proximity to the surging line;
build-up of pressure underneath the fire bar of the blast furnace;
smoothing of pressure gaps;
user-friendly and easy control over the unit;
more accurate measurement of technological parameters;
periodic backup of parameters measured and automatic records of all
parameters at critical situations.
In compliance with the Technical Terms of Reference and
Technical and Economic Feasibility Report, implementation of the project has boosted the
pressure under fire bar by 0.3 bar and over, significantly lowered energy consumption and
increased productivity of the blast furnace because each extra 0.1 bar of pressure leads
to:
1% increase in furnace’s productivity;
0.5% coke saving;
20 to 40% reductions in ejection of blast furnace dust.
The CCC System has a payback period of around 6 months.
High accuracy and quick response of the CCC System boost reliability and efficiency of
metalmaking machinery. In addition, highly effective patented control algorithms and
limitations are applied to ensure accurate sustenance of particular parameters in
statistics and transient states. The hydraulic portion of the current control system has
been upgraded. Moreover, high effectiveness of the anti-surge controls makes it possible
to increase the discharge pressure and, consequently, the furnace’s productivity owing
to a substantial reduction in the distance of operating compressor from the surging line.
The main advantages of the CCC System are the algorithm
software, contingency plans in case of sensors’ failure and rather simple configuration.
At the moment, almost all metallurgical mills of the USA, as well as European, Canadian,
Chinese and South American mills, make use of the CCC Systems. CCC firm is the global
leader in turbine and compressor controls. Throughout 25 years CCC has sold and installed
over 6,000 CCC Systems. In 1995 the company was awarded an Honorary Diploma of the US
Department of Energy for meritorious achievements in energy saving.
Krivorozhstal is the first among Ukraine’s and CIS
integrated mills to introduce such a control system. Former director general Oleg Dubina,
who is currently the Vice Prime Minister of Ukraine, made a decision to install the CCC
System in Blast Furnace No.9, the biggest of its kind in Europe. Other metallurgical mills
of Ukraine have also presented similar projects, e.g. Zaporozhstal, Dzerzhinsky Iron &
Steel Works, Ilyich Iron & Steel Works, Azovstal, Alchevsk Iron & Steel Works,
Yenakievo and Donetsk Metallurgical Works. Besides, Zaporozhye Iron Ore Works has started
executing a similar system at three electric compressors. Owing to assistance rendered by
Metallurgprom Association (director general Kharakhulakh), the Energy Saving Program of
Dnepropetrovsk Region and draft Development Program for Ukraine’s Mining and
Metallurgical Complex Until 2005 provide for implementation of such projects in the
country.