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VD/VOD TREATMENT

The vacuum treatment (VD) is one of the most commonly used commercial degassing process. Therefore a ladle is placed inside a vacuum tank and closed with a vacuum cover for operation under vacuum conditions. The ladle is equipped with a porous plug for inert gas stirring. Vacuum is created by steam ejector system or by dry mechanical vacuum pumps. The main purpose of the vacuum treatment is to reduce to the required limit values, carbon, oxygen, nitrogen and hydrogen. The VD system can also be equipped with vacuum alloy hoppers so that an analysis correction and final adjustments can be made. Further advantages of the process are excellent homogenization and high alloy yields. During VOD treatment very low carbon contents and high chromium yield can be achieved by oxygen blowing under vacuum operation. Most production programs nowadays require a combination of VD and VOD operation. For that purpose, the equipment can be designed for both types of operations.

Overall, VD/VOD treatment offers the following process advantages:

  • Utilisation of cheaper materials with high carbon content
  • Reduction of production costs
  • Improvement of quality thanks to low gas content
  • Ability to produce ELC qualities with minimum chromium loss
  • Achievability of strict analysis tolerances
  • High chromium yield
  • Single or twin operation stand
  • Heat sizes up to 350t
  • Steam ejector vacuum pumps and dry mechanical vacuum pumps
  • Alloying under vacuum conditions

The right auxiliary equipment is crucial for efficient, high-quality and safe production. Precise temperature measurements, automatic sampling and robust and high-temperature resistant components such as the gas coupler not only increase quality, but also improve operator safety. In addition, INTECO’s “zero-leakage” design helps to keep pump down and treatment times short and thus reduces operating costs. Sophisticated concepts for vacuum tank transfer cars and ladle covers complete the package.

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Vacuum pumps
Today, mechanical vacuum pumps are usually used in vacuum degassing systems. Thanks to filters and gas coolers, with mechanical pumps both VD and VOD operation is possible. Of course, INTECO plants can also be supplied with conventional steam ejector vacuum pumps (also in combination with water ring pumps).
Wire feeding machine
Wire feeding is known as the most precise process to add small quantities of deoxidants and alloys into the melt. INTECO supplies wire feeding machines along with the entire wire guiding systems and coil storage.
Oxygen lance
The water-cooled oxygen lance is designed for the required blowing rate and is used for chemical heating or decarburization. The patented stuffing box enables smooth operation. As an alternative, consumable oxygen lances can be used.
Manipulators and robots for measurements
Temperature measurements, hydrogen content measurements and sampling performed by robots or manipulators ensure consistent and reproducible results. In addition, automatic sample manipulation systems reduce the need for manual work.
Vacuum lock system
The vacuum vacuum lock system allows the addition of alloys under vacuum.
Ladle cover
A heat shield and a ladle cover protect the vacuum cover from radiant heat as well as steel and slag splashes. The water-cooled design eliminates the need for refractory material. The ladle cover serves as a free-board extension and enables high stirring rates, which ensure very effective degassing.
Fixed vacuum tank or vacuum tank transfer car
INTECO offers the tailor-made solutions for every customer. Depending on capacity requirements and available space, single or double-stand systems can be realized. Vacuum tank transfer cars with fixed stationary covers or vacuum cover cars with fixed tanks are used.
Gas Coupling System
INTECO’s gas couplers are resistant to high temperatures and specially designed for use in vacuum tanks. They enable a fully automatic connection to the purge gas control system and drastically increase operator safety.

Central Socket

A unique feature of the INTECO VD/VOD system is the consistent “zero-leakage design”. All operations, such as wire feeding, temperature measurement and sampling, are carried out through the central socket. As only one single opening is required in the vacuum cover, there is less risk of leakage. This results in very short pump-down and treatment times and low operating costs.

Digitalisierung und Smart Production sind die treibenden Kräfte für Entwicklung und Veränderung in der Stahlbranche. Bei INTECO bieten wir Ihnen nicht nur erstklassiges Engineering im Anlagenbau, sondern auch maßgeschneiderte digitale Lösungen, die den anspruchsvollen Anforderungen unserer Kunden gerecht werden. Überwachen Sie Ihre Produktion effizienter und nutzen Sie die gesammelten Informationen für Anpassungen und Fortschritt.

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Oxygen and decarburization model

The oxygen model calculates the required amount of oxygen to achieve target decarburization, considering initial steel samples and current temperature that lead to a physically based oxygen quantity. It uses the basics of the thermochemical and thermodynamic approach and once the vacuum and/or oxygen blowing has started, the decarburization model tracks the oxidation of the elements involved. The chemical composition is updated through close interaction with the thermochemical model. The decarburization model reacts to the oxygen injection rate and oxidizes the steel according to the thermodynamic evaluations. The decarburization model constantly checks stoichiometric oxidation against kinetic reactions and the temperature gain is back-looped to the temperature model. The degassing model calculates the removal of hydrogen and nitrogen.

INTECO’s Material Handling System Automation

INTECO’s Material Handling System Automation offers precise and time-critical alloying for all secondary metallurgy plants. Its recipe-based approach serves various technologies such as positive and negative weighing, shuttles, weighing bands, or hoppers and integrates micro-dosing systems and wire feeding machines. Moreover, it provides fallback modes for redundant feeding lines as well as sequential dosing of materials or material groups to add slag builders and alloys in the correct order.

Smart process camera

The smart process camera is a retractable and therefore well protected optical system that directly streams a high-resolution video to the control room to ensure safe low-manpower operation. The optional thermal imaging variant provides a clear view through smoke and dust and serves for automatic stirring adjustment. Additional generated process information such as slag height and stirring eye detection enhances metallurgical model accuracy and safety.

Temperature and thermochemical model

The thermochemical model calculates oxide and element activities based on current process conditions and events, current heat state and energy losses and gains. In this context, IMAS modeling includes a thermophysical property library, reaction enthalpies, coefficients for interactions providing the necessary parameters, and coefficients to determine and calculate the activities.

The temperature model accounts for the temperature losses due to radiation and convection as well as the changes in temperature due to purging, material addition and heating. Temperature changes due to reactions are also taken into account and are therefore coupled with the basic thermochemical model. Both are not only used to calculate the actual heat state but also to predict take-over time and temperature.

Degassing model

The degassing model calculates the reduction of hydrogen and nitrogen in the VD system.

IPAS off-gas measuring system

The IPAS off-gas measuring system/device for VOD applications includes a gas extraction system, an off-gas analyzer and a flow measurement device. The off-gas analyzer measures CO and CO2 using an infrared photometer, H2 using thermal conductivity and O2 using electromagnetic force measurement. The flow meter works based on ultrasound measurements or hot-wire anemometer and is supplied with temperature and pressure data for normalization to standard cubic meters per hour. The IPAS system is self-calibrating and works with online process models for hybrid decarburization and degassing modelling.

IMAS process automation

IMAS-PA-VD/VOD provides advanced top-down process guidance through dynamic or static treatment planning and integrated optimization tools. Process supervision is massively improved by the cockpit view and integrated real-time process models. IMAS provides instant real-time information and alerts, based on which the operators can control and steer the process just-in-time. The heat-based data recording stores sensor data, including complex information such as video streams, allowing observation of real-time data for quality assurance and process improvement.

PROJECTS

Nucor Darlington

Mechanical vacuum pump system Single-tank unit with moveable cover, alloy lock system and all complementary auxiliaries
Type: 110t VD

Taewoong Special Steel

Steam ejector pump system, Twin- tank unit with moveable cover, O2 blowing lance, alloy lock system and all complementary auxiliaries
Type: 150t VD/VOD

Grupo FRISA

Mechanical vacuum pump system Twin- tank unit with moveable cover, O2 blowing lance, alloy lock system and all complementary auxiliaries
Type: 50t VD

Deutsche Edelstahlwerke
Specialty Steel

Steam ejector pump system Moveable vacuum tank unit with fix cover, O2 blowing lance, alloy lock system and all complementary auxiliaries
Type: 130t VD/VOD

Taigang Stainless Steel

Steam ejector pump system Twin VD-plant with moveable vacuum tanks,fix cover, O2 blowing lance, alloy lock system and all complementary auxiliaries
Type: 45t VD/VOD

Inteco Group Headquarters

INTECO melting and casting technologies GmbH
Wienerstrasse 25
A-8600 Bruck a.d. Mur

+43 (0)3862 53110 0
+43 (0)3862 53844
inteco.austria@inteco.at

INTECO melting and casting technologies GmbH

1) Vacuum pumps

Today, mechanical vacuum pumps are usually used in vacuum degassing systems. Thanks to filters and gas coolers, with mechanical pumps both VD and VOD operation is possible. Of course, INTECO plants can also be supplied with conventional steam ejector vacuum pumps (also in combination with water ring pumps).

2) Wire feeding machine

Wire feeding is known as the most precise process to add small quantities of deoxidants and alloys into the melt. INTECO supplies wire feeding machines along with the entire wire guiding systems and coil storage.

learn more
3) Oxygen lance

The water-cooled oxygen lance is designed for the required blowing rate and is used for chemical heating or decarburization. The patented stuffing box enables smooth operation. As an alternative, consumable oxygen lances can be used.

4) Manipulators and robots for measurements

Temperature measurements, hydrogen content measurements and sampling performed by robots or manipulators ensure consistent and reproducible results. In addition, automatic sample manipulation systems reduce the need for manual work.

5) Vacuum lock system

The vacuum vacuum lock system allows the addition of alloys under vacuum.

6) Ladle cover

A heat shield and a ladle cover protect the vacuum cover from radiant heat as well as steel and slag splashes. The water-cooled design eliminates the need for refractory material. The ladle cover serves as a free-board extension and enables high stirring rates, which ensure very effective degassing.

7) Fixed vacuum tank or vacuum tank transfer car

INTECO offers the tailor-made solutions for every customer. Depending on capacity requirements and available space, single or double-stand systems can be realized. Vacuum tank transfer cars with fixed stationary covers or vacuum cover cars with fixed tanks are used.

8) Gas Coupling System

INTECO’s gas couplers are resistant to high temperatures and specially designed for use in vacuum tanks. They enable a fully automatic connection to the purge gas control system and drastically increase operator safety.

learn more
9) Central socket

A unique feature of the INTECO VD/VOD system is the consistent “zero-leakage design”.  All operations, such as wire feeding, temperature measurement and sampling, are carried out through the central socket. As only one single opening is required in the vacuum cover, there is less risk of leakage. This results in very short pump-down and treatment times and low operating costs.

1) Oxygen and decarburization model
to achieve and maintain the target element composition

The oxygen model calculates the required amount of oxygen to achieve target decarburization, considering initial steel samples and current temperature that lead to a physically based oxygen quantity. It uses the basics of the thermochemical and thermodynamic approach and once the vacuum and/or oxygen blowing has started, the decarburization model tracks the oxidation of the elements involved. The chemical composition is updated through close interaction with the thermochemical model. 

The decarburization model reacts to the oxygen injection rate and oxidizes the steel according to the thermodynamic evaluations. The decarburization model constantly checks stoichiometric oxidation against kinetic reactions and the temperature gain is back-looped to the temperature model. The degassing model calculates the removal of hydrogen and nitrogen.

2) INTECO’s Material Handling System
for precise and fast alloying

INTECO’s Material Handling System Automation offers precise and time-critical alloying for all secondary metallurgy plants. Its recipe-based approach serves various technologies such as positive and negative weighing, shuttles, weighing bands, or hoppers and integrates micro-dosing systems and wire feeding machines. Moreover, it provides fallback modes for redundant feeding lines as well as sequential dosing of materials or material groups to add slag builders and alloys in the correct order.

3) INTECO's smart process camera
to safely monitor operation

The smart process camera is a retractable and therefore well protected optical system that directly streams a high-resolution video to the control room to ensure safe low-manpower operation. The optional thermal imaging variant provides a clear view through smoke and dust and serves for automatic stirring adjustment. Additional generated process information such as slag height and stirring eye detection enhances metallurgical model accuracy and safety.

4) Temperature and thermochemical model
for real-time temperature, steel and slag analysis

The temperature model accounts for the temperature losses due to radiation and convection as well as the changes in temperature due to purging, material addition and heating. Temperature changes due to reactions are also taken into account and are therefore coupled with the basic thermochemical model. Both are not only used to calculate the actual heat state but also to predict take-over time and temperature.

The thermochemical model calculates oxide and element activities based on current process conditions and events, current heat state and energy losses and gains. In this context, IMAS modeling includes a thermophysical property library, reaction enthalpies, coefficients for interactions providing the necessary parameters, and coefficients to determine and calculate the activities.

5) Degassing model
to calculate the reduction of hydrogen and nitrogen

The degassing model calculates the reduction of hydrogen and nitrogen in the VD system.

6) IPAS off-gas measuring system
for measuring the gas composition

The IPAS off-gas measuring system/device for VOD applications includes a gas extraction system, an off-gas analyzer and a flow measurement device. The off-gas analyzer measures CO and CO2 using an infrared photometer, H2 using thermal conductivity and O2 using electromagnetic force measurement. The flow meter works based on ultrasound measurements or hot-wire anemometer and is supplied with temperature and pressure data for normalization to standard cubic meters per hour. The IPAS system is self-calibrating and works with online process models for hybrid decarburization and degassing modelling.

7) IMAS process automation

IMAS-PA-VD/VOD provides advanced top-down process guidance through dynamic or static treatment planning and integrated optimization tools. Process supervision is massively improved by the cockpit view and integrated real-time process models. IMAS provides instant real-time information and alerts, based on which the operators can control and steer the process just-in-time. The heat-based data recording stores sensor data, including complex information such as video streams, allowing observation of real-time data for quality assurance and process improvement.