Cost Reduction

The production costs of glass are mainly affected by labour, batch and furnace. Almost 40% of the glass production costs are related to raw materials and melting. While the labour cost reduction requires a detailed workflow analysis, which is not conducted many times in practice, the energy and batch costs can be reduced by technical calculations on a daily basis.

Table: Typical production costs of glass production

Our software package YIELD provides calculation tools to reduce the energy consumption and the raw material costs. The concept of YIELD allows an optimisation on a daily basis.

Energy Consumption Reduction

Energy consumption was widely and intensively discussed in the past. In YIELD, the most important and most commonly used approaches were included. Additionally, a unique solution finder guides the operator through the calculation. Thus, there are no requirements for a technical expertise of the operator. Of course, also input masks for sophisticated calculations of glass experts are included.

YIELD offers subroutines to calculate the effect of

• Varying excess oxygen concentrations
• Recuperative and regenerative preheating
• Oxy-Fuel conversion
• Oxy-Fuel boosting
• Leakage air reduction
• Glass temperature reduction
• Combustion temperature reduction
• Fuel change
• E-boosting

Every calculation provides the operator with both financial and technical evaluations and comparisons. The table shows the results for a standard regenerative end-port furnace were summarised.

Table: Technical and Financial results of YIELD calculations

O2 reduction in flue gas

A reduction of the oxygen concentration in flue gas by reducing the total quantity of combustion air results in a decreased energy consumption, because there is less useless nitrogen that has to be heated up uselessly. Additionally, the flame temperature rises and the heat transfer to the glass bath is increased. Depending on the furnace, values down to 1% O2 in the flue gas can be reached without producing noteworthy CO concentrations. Thus, energy savings in the range of several percent are possible and can result in profit increases by several hundred thousand Euros per year. Normally, the cost for the optimisation is almost zero and the effect is only limited by the furnace condition.

YIELD allows the calculation of the profit increase by excess oxygen reduction and provides the operator with all technical data to evaluate the applicability.

Switching from recuperative to regenerative preheating

Preheating the combustion air regeneratively instead of recuperatively increases the preheating efficiency dramatically. The preheat temperature increases from around 500°C up to 1,350°C, and the energy cost savings exceed the increased investment cost by far.

YIELD allows the calculation of these values and compares both kinds of preheating from the technical as well as from the financial point of view.

Oxy-Conversion

Oxy-Fuel conversion means converting the furnace from air-firing to complete oxy-fuel firing. The increased combustion temperatures and efficiency finally result in profit increases. As the financial and technical consideration is quite complex, YIELD includes all required background information to calculate the financial and technical effects. The calculation includes factors like oxygen price, reduced wall losses, increased heat transfer, reduced flue gas volume and allows to compare liquid versus VPSA oxygen supply.

Oxy-boosting

The installation of additional oxy-fuel burners can decrease the fuel consumption, especially near the end of the furnace life time. YIELD allows to calculate the technical and financial aspects of oxy-fuel boosting and contains all required technical and financial background information. The calculation considers factors like oxygen price, reduced wall losses, increased heat transfer, reduced flue gas volume and allows to compare liquid versus VPSA oxygen supply.

Leakage air reduction

Reducing the leakage air will result in a controlled combustion and will reduce the energy consumption. Especially large leakage air volumes increase the required excess oxygen concentration at negligible CO concentrations. YIELD provides all required subroutines to calculate the profit increase by reducing the leakage air.

Glass temperature reduction (Quality issues)

The glass temperature is one of the key parameters in glass melting and is considered as critical. But nevertheless, in some cases it is worth to reduce the glass exit temperature. A temperature decrease of 1% results in a reduction of the energy consumption of up to 1.6%. The actual energy reduction depends on many parameters. YIELD is able to calculate the potential energy reduction based on a specified glass temperature reduction.

Changes of glass temperatures always require a detailed analysis in advance to consider the effects on glass quality.

Fuel change

Changing the fuel can reduce the energy costs. Important to consider are the calorific values of the fuels and of course the fuel cost. Changing the fuel can require a change of the burners and the related fuel supply equipment. The costs and profits can be calculated with YIELD.

E-boosting

Equipping furnaces with electrical boosting can result in profit increases, especially if payments for carbon credit were done. With YIELD, the operator is able to calculate the maximum possible profit realisable with e-boosting considering CDM.

CFD/Consulting

The financial and technical effects of the presented energy cost reduction approaches can be calculated by YIELD. YIELD is a powerful tool to get evaluations of different technologies. The installation of energy reduction tools requires a more sophisticated analysis of limiting boundary conditions. We suggest to contact our engineering team at consulting@glassglobal.com, before starting the installation.

We can help you by initiating CFD-Studies, contacting suppliers and providing sophisticated studies.

Batch and Raw material costs reduction

The raw materials required for glass production are weighed out in certain quantities in accordance with the glass composition and mixed with each other. A batch is therefore understood to be the weighed out ratio of the raw material quantities in the mixed state that is necessary for the production of a glass with a particular composition.

The term batch formula is understood to mean the defined weight of a particular quantity of glass containing the individual components calculated for a previously defined total quantity.

Due to different raw material costs, transport cost, specific melting costs and melting losses the total cost of a batch depends on the batch formula.

Thus cost reduction of batch materials can be realised by substitution of raw materials by cheaper ones or by optimisation of the batch formula.

Optimization of batch formula

A first approach for batch formula optimisation is a mathematical subroutine, which optimises the costs. YIELD considers costs of transport and purchase as well. The integrated glass property calculation tools ensure comparable properties of glasses produced from the new batch formula. The result is a cost driven optimised batch formula at specified glass properties.

Substitution of raw materials

Considering just the batch formula costs is only acceptable as a first approach. It should be understood that a batch formula is imaginable, which gives minimum purchase and transport costs, but results in increased melting costs. Thus, the batch formula must also be optimized by melting costs and raw material costs. YIELD provides integrated iteration subroutines to choose the kind of optimisation:

• Energetic
• Financial
• Both energetic and financial

The integrated glass property calculation tool ensures comparable properties of glasses produced from the new optimised batch formula.

Optimization of transport costs

The batch section of YIELD is able to include transportation costs in the batch cost calculation and all optimisation subroutines.

Consulting

The financial and technical effects of the presented cost reduction approaches can be calculated by YIELD. YIELD is a powerful tool to get evaluations of different technologies. The installation of the approaches requires a more sophisticated analysis of limiting boundary conditions. We suggest to contact our engineering team at consulting@glassglobal.com, before starting the installation.

We can help you by initiating CFD-Studies, contacting suppliers and providing sophisticated studies.

Emission cost reduction

Today, most glass producers have issues with their CO2 and NOx emissions. While exceeding the CO2 concentrations results in buying carbon credits, NOx emissions have to be kept under the environmental limits. For more information please look at chapter 4 Emission Reduction.

The financial and technical effect of the presented cost reduction approaches can be calculated by YIELD. YIELD is a powerful tool to get evaluations of different technologies. The installation of the approaches requires a more sophisticated analysis of limiting boundary conditions. We suggest to contact our engineering team at consulting@glassglobal.com , before starting the installation.

We can help you by initiating CFD-Studies, contacting suppliers and providing sophisticated studies.

For further information please contact our engineering team at consulting@glassglobal.com.