260 tpd end fired furnace at Vetropack, Croatia with many technological improvements

In Straža the company is not only a supplier to the Croatian domestic market, but also a key exporter to neighboring markets in Slovenia, Italy, Hungary, Bosnia, Serbia and other countries in south-eastern Europe.  In March 2004 HORN built already the container glass furnace 62 which was now due 11 years later.At beginning of 2015 the furnace for container glass was repaired by HORN. The furnace produces three different glass colors: olive, green and amber.

Together with Vetropack HORN made many technological improvements to control the melting process.

Picture 1: Cold repair of furnace 62 at Vetropack Straža, Croatia

Combustion system

The complete combustion system has been changed to the latest technology. Therefore HORN supplied the individual burner control combustion system with the latest DUALFLAME AC burners. In addition all the gas stations and burners at distributor and forehearth are changed to a modern combustion system using independent left and right control of the temperature in each cooling section of the forehearths.

Natural gas chromatograph

As a special figure the furnace got a Natural gas chromatograph, type SIEMENS Sitrans CV, to analyze the gas composition. Moreover the Sitrans CV can calculate the upper and lower heat value, gas density, Wobbe Index and specific gravity.

Picture 2: Natural gas chromatograph, type SIEMENS Sitrans CV

Continuous monitoring of the redox potential

For the continuous measurement of the glass redox potential a new sensor at the forehearth had been installed. The water cooled sensor contains a thermocouple and an oxygen cell. Both provide a mV-signal to an IOSI-01 oxygen interface, which converts these two mV-signals to three, programmable, loop powered 4..20 mA analog outputs. In the standard configuration the three 4-20 mA output channels represent glass melt temperature, Oxygen cell emf and Oxygen partial pressure. This information allow Vetropack to observe the glass melt and to modify preventive the glass composition in order to avoid glass quality problems.

Lambda control of the combustion system at forehearths

To adjust the mixture ratio of Air and Natural gas automatically at the forehearth combustion systems HORN installed an extractive and heated oxygen sensor MPLS from the daughter company EUROX at each forehearth. With this unit the oxygen content of the premixed Natural Gas / air and thus the atmosphere of the combustion space of the forehearth can be controlled to a constant level.

The MPLS contains a zirconia measuring cell which is heated to an exceptionally high temperature of 900°C. A slight portion of the gas-air-mixture is fed to the heated sensor where a complete catalytic transformation takes place. The unique design of the measuring cell and its heating facility determines the real residual oxygen content according an “ideal, complemented combustion”. Along with a control equipment the ratio of the gas-air-mixture can be fine-tuned in order to keep a constant oxygen value in the forehearth atmospheres either for oxidizing or for reducing atmospheres as well.

The very short reaction time of the sensor allows switch-over times of only 2 minutes and thus the multiple collecting of up to 10 sampling points by each measuring unit. For this purpose the unit is equipped with a solenoid valve block to collect the samples of the different forehearth control sections.

Picture 3: extractive and heated oxygen sensor MPLS from EUROX

Beside the above mentioned, HORN supplied the complete refractory and steel drawings, forehearth superstructure cooling, steel parts, tank and throat cooling, reversal system, waste gas ducting, electrical control system, computer supervisory system PCS7 V8, electric boosting equipment, cooling water, TV camera and stirrers for all 3 lines.

As a well-known supplier, HORN carried out the complete project with all services for steel, refractory, heating-up and successful commissioning.