Process optimization

Computational Fluid Dynamics

GTM-X is a Computational Fluid Dynamics (CFD) tool for detailed modelling of physical and chemical processes in complex shapes. Running on different platforms, this multi-physics model permits a wide variety of materials to be simulated and many different physical equations to be addressed, including turbulence and combustion processes and their influence on glass melts. CelSian’s highly valued support team assists our customers for addressing specific requirements.

Please watch the movie below to get an idea of the possibilities of GTM-X.

Many years of experience confirm the abilities of CelSian modeling expertise, where validation data is created for new and existing glass melting furnaces and project results can be presented in a variety of different ways. A large portfolio of simulations is maintained in the CelSian database, helping to validate the accuracy of the latest models created on behalf of customers.

Today, before starting up a new furnace installation, it is hard to meet all requirements without proper modeling upfront. The main advantage of our modeling software is that accurate predictions in relative process changes can be created. This is often followed by optimization studies via the completion of case studies on process variations on the base case. Via regular communication with the customer and based on the modeling results generated, recommendations for helpful improvements can be provided. Project results can be provided in a variety of different ways, ranging from interactive presentations to the provision of software tools where customers can use the results themselves. At CelSian, modeling results are combined with expertise.

Lab experiments and glass quality

We are proud to work in what once was Philips Glass Research labs, our high tech equipment and services are available for our customers.


Evolved Gas Analysis (EGA)

With our HTMOS-EGA equipment we analyze glass forming raw material batches during heating process up to 1600 °C and observe foaming & bubble formation. We report on

• Identification gas evolving reactions in batch

• On-set of fining (fining onset temperature)

• Bubble growth & ascension in melt

• Foam evolution

• Foam decay

• Effect of furnace atmosphere on fining

• Effect of furnace atmosphere on redox

• Effect of furnace atmosphere on foaming


Batch pretreatment tests

• Pelletizing

• Briquetting

• Milling & Sieving

• Activation of batch materials by mechanical pretreatment of batch


Batch melting tests 10-10000 grams

• To develop new glass types

• For glass samples e.g. glass bars, ingots

• In different furnace atmospheres


Batch heat diffusion (l/r·cp) measurements

• Simulation of batch blanket: 5-10 cm

• Measuring temperatures at different levels from heated plate as function of time


Fining tests

• Movies of bubbles in molten glass

• Fining onset temperature

• Monitoring bubble size and ascension

• Effect of furnace atmosphere of bubble removal

• Effect of batch composition and fining agents on bubble behavior


Helium Extraction

• Helium extraction of dissolved gases from glass melts

• Determination dissolved gases (N2, SO2, CO2) in production glasses

• Determination of dissolved gases in saturated melt (solubility measurements: N2, CO2, SO2, O2)


Refractory exposure tests

for regenerator simulations with simulated glass furnace flue gases (1400-500 °C)

• Flue gases with water vapor, O2 or CO, N2, CO2, salt vapors (Na or K vapors), SO2

• Different refractory qualities (based on MgO, Al2O3, ZrO2, Cr2O3, SiO2 or combinations of these refractory oxides) and binding phases in refractory

• Chemical attack of these refractory materials depending on flue gas composition, reducing/oxidizing conditions and temperature


Refractory exposure test in molten glass

• Rotating refractory finger in melt (comparative tests

• Standard refractory tests for glass melt contact


Batch-Free-Time (BFT) tests for batches

• Determination of time for complete melting of batch (no crystalline inclusions in melt) at isothermal conditions

• Typical temperatures 1350, 1400, 1500 °C

• Effect of batch composition on BFTEffect of grain sizes on BFT

• Effect of batch pretreatment (pelletizing, humidification) on BFT

• Effect of melting flux additions on BFT


Glass melt gas saturation tests

• Determination dissolved gases (N2, SO2, CO2) in production glasses

• Determination of dissolved gases in saturated melt (solubility measurements: N2, CO2, SO2, O2)


Evaporation (transpiration) experiments

• Determination chemical activity of volatile glass species in melt

• Evaporation rates and detection of volatile species, depending on:

• Glass composition

• Impurities in glass

• Furnace atmosphere

• Gas velocity above melt

• Temperature

• Time


Glass analysis: Glass composition after dissolution (ICP-ES and Ion Chromatography)

• Surface tension and glass melt density by sessile drop (up to 1250 °C)

• Surface tension by capillary bubbling, up to 1550 °C

• Leaching tests: Composition of leaching solution, leaching tests of glass or glass cullet

• Water / Hot water

• Acideous solutions or Alkaline solution

• Alcohol containing solutions


Applying Rapidox glass melt pO2 measurements

• Effect of type of cullet on pO2 (redox state)

• Effect of fining agents

• Effect of oxidants or reducing agents on melt


CelSian re-uses the information from its GTM-X Computational Fluid Dynamic (CFD) modelling in the design of Advanced Process Control for melters and forehearths.

Our control system can include variables that are nearly impossible to model by observation. Cullet percentage variations, pull or colour changes and variations of ambient temperature are all included in our system. There is no need to re-execute plant tests in the case of changes in geometry, process conditions or glass composition.

Customers using rMPC have confirmed multiple benefits for control in parallel, such as:


  • Combined control of glass/bottom temperatures.
  • Reduced effect of variations in batch quality, pull and calorific value of the fuel.
  • Reduced operator interventions.
  • Have one control strategy for all shifts.
  • Reduced time to recover from disturbances.
  • Push to maximal furnace load.
  • Reduced energy consumption and optimised emissions.


Glass manufacturers do their utmost to run their melters as stable as possible. GTM-X CFD modelling together with our rMPC control unit support our customers in maintaining stable glass conditions.