How to improve forming and save energy

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«Depending on local conditions, almost 50% of the glass cost is energy».
This basic principle is the key to understanding why it is so important to reduce the use of energy during glass container production.

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How to improve forming and save energy

  1. 1. How to Improve Formingand Save Energy Mauro FerreroArticle published in GLASS WORLDWIDE, 2011
  2. 2. How to Improve Formingand Save Energy « Depending on local conditions, almost 50% of the glass cost is energy».This basic principle is the key to understanding why it is so important to reduce the use of energyduring glass container production. Reducing energy costs allows us to work on the largestcomponent of finished product cost. Energy is an essential component in glass manufacturingand it comes in many forms. In this article, we examine the electrical power, used to generatethe huge flow of compressed air necessary to operate the IS machines of every manufacturer. The generation of compressed air, in and to shut down part of the air Chinese restaurants all over Europe andboth high and low pressure lines, is achieved compressors? other countries. Tsingtao is the fifth largestusing air compressors and it is common to The answer is yes and the purpose of this brewery in the world with a total volume offind utility rooms with 600-800 kW of paper is to analyze the use of vacuum not as a 50 Million hectoliters in 2009.installed power in glass factories. The total replacement of compressed air but as a The bottle on the right is the proprietarycompressed air consumption depends on combined force able to reduce the bottle of “Birra Peroni”, a common Italianthe specific settings of the IS lines thus consumption of air and, at the same time, to beer, found in every super market.making every single glass factory a unique help the forming process of the containers.case.However one element is common to all glassworks: the generation of compressed airtakes a big bite out of the power bill of the What do these bottlesfactory. have in common?Lets make a simple calculation:Cost of power: approx 0,12 Euro/kWh (inItaly).Assuming 8.700 working hours in one year,hence every single kW costs 1.050Euro/year. Picture 2 - 522 grams vs 283 gramsIf we go back to the total consumption of theair compressors and we assume that we have The weight difference is astonishingan installed power of 800 kW with a real (-45.7% of glass) and there is a lot ofpower consumption of approx 700 kW “technology” and development to go from(depending on the loading/unloading cycles the green bottle weighing 522 grams for 66and assuming approx 90% on loading cl. to the amber bottle that uses only 283condition), than the pure cost of the energy grams of glass for the very same capacity.used by air compressors is 730.000 This “technology” covers every single aspectEuro/year. of container making and starts from the rightOf course, energy cost varies significantly mix all the way to the lehr. However in the ISfrom one country to another and it can be lines one essential player in light weightvery different. Unfortunately, energy in Italy containers manufacturing is the use ofis one of the most expensive in Europe and vacuum assisted forming.there are no signs of improvement on this Picture 1 - 66cl capacity beer bottles, Chinese andissue. However, even adapting the energy Italian productioncost to what is typical in France, one of the Vacuum on the blowbest cases in Europe, and considering a Very little if we exclude that they are bothvalue of 0,07 Euro/kWh, the same made of glass and they have the same sidecalculation would produce a total cost of capacity of 66 cl.approximately 426.000 Euro/year. Still a The bottle on the left is made for Tsingtao, The use of vacuum on the blow side isserious amount of money. probably the most popular Chinese beer, one of the most common applications. It hasThus the question: is it possible to use less air available almost everywhere including been in use for years, it requires moulds with
  3. 3. Cost of vacuum and cost of air It is extremely difficult to evaluate the cost differences comparing flows. However it is possible to compare the cost of a specific operation when it is made with vacuum or when it is made with air. In short and without entering in too many details, we can state that, if and when a specific operation can be done using vacuum instead of air, than the cost to produce that energy is about one fourth of the cost to produce compressed air. Producing vacuum efficientlyPicture 3 - IS machine in operation producing different containers (courtesy of Bottero S.p.A.) Contrary to compressed air, vacuum is difficult “to be seen”, often misunderstoodvacuum vents and channels and the IS of the blow head of the IS machine. In this and even more often regarded as amachine must be arranged for the use of it. case only vacuum is used to form the “secondary utility”. Furthermore, whileToday, all IS manufacturers propose vacuum container. The effect of a good vacuum on compressed air is always produced byon the blow side as a standard feature. the blow side is so strong that it is possible to centralized systems, vacuum is oftenVacuum is achieved through a series of tiny complete the forming of the container using produced “on board” with small pumps thusventing holes connected to channels in the only vacuum. Unfortunately it is not possible not taking advantage of the possible savingssides of the mould and are evenly distributed to use only vacuum in the standard of a centralized system.on the upper part of the container beginning production because the containers would be Vacuum can be produced in several waysat the height of the shoulder of the bottle and still too hot at the end of the forming. and our experience has shown that verygoing up towards the neck. They are often Nevertheless it clearly shows how and to often it is produced with poorly engineeredhidden in the engraving, when this is present, what extent vacuum can influence the equipment or with obsolete technologiesand in this case vacuum also helps the forming process. loosing, in this way, the advantage of anmovement of the glass inside the small groves alternative and cheaper force to compressedthat will give the bottle its proprietary look. air. A vacuum pump is a piece of technologyThe diameter of the vacuum venting holes Vacuum on the blank and it deserves the engineering and know-varies from a minimum of 0,4 mm to a how of a high technology equipment. First ofmaximum of 0,7 mm. The diameter is an sideoption of the mould maker and it depends on Vacuum can be used on the Picture 4 - Glass mould with vacuum venting holes in the upperthe container shape and use. blank side with very interesting part (courtesy of Busellato Glass Moulds Srl)Vacuum works as an additional force, advantages in compressed airtogether with the blow of compressed air and savings as well as in the quality ofthe combination of push & pull of the two the container and in theactions helps the forming process by production speed.increasing its speed, contributes to an even The idea is to “pull down” thedistribution of the glass on the side of the gob with vacuum instead ofcontainer and allows to reduce the gob “pushing down” the gob with theweight. settle blow. In this case vacuumRemoving the air that remains entrapped can almost replace the use of thebetween the side of the container and the side settle blow and experiencesof the mould also helps to remove the heat gathered with Quantumfrom the mould keeping its temperature Engineered Products haveunder control.An additional benefit of the use demonstrated that the use ofof vacuum is that it allows to slightly reduce vacuum on the blank side maythe use of compressed air that is, at least dramatically reduce the settlepartially, replaced by vacuum. Reducing the blow angles from usual 35/40°,blow of air reduces the use of compressed air down to 4 to 5°. That is aboutthus saving energy. saving 85 - 90% of compressedOne of the systems used to show the “vacuum air and time dedicated to thisat work” in glass forming is to stop the action operation.
  4. 4. As the glass fills the finish, the vacuum also helps to cool and set the finish. With this process, the finish can be made and set with reduced settleblow. By using the vacuum to help load deeper and set the finish, the gob will flow better and easier into the finish. Picture on the left: Blank mould with vacuum loading (courtesy of Quantum Engineered Prod.) Picture on the right: Loading gobs entering the blank moulds (courtesy of Emhart)all, a vacuum pump must be a vacuum pump vane pumps, result of 85 years offrom the very beginning of the project. The experience in vacuum and hundreds ofuse of reversed compressors or “any” pump installations with thousands of pumps incan bring unpleasant surprises in terms of operation all over the world. From polarefficiency or Life Cycle Cost of the equipment. climates to tropical locations air cooledThe rotary vane technology used in rotary vane vacuum pumps keep deliveringPneumofore pumps is, by far, the most the same solid performance year after yearefficient way to produce vacuum in industrial of operation offering the lowest Life Cycleapplications. A rotary vane pump is designed Cost available in this market.to be a vacuum pump, while rotary screwpumps are generally compressors Picture 5 - Mould with stipped finishing and vacuum venting on all the surface (courtesy of Strada Srl)“transformed” into pumps. The efficiencyand the consistency of performance of arotary vane pump is just an impossible targeteven for the best liquid ring pumps, eitherwith water or oil sealing liquid. Mauro Ferrero is Director ofThe rotary vane technology is based on the Sales at Pneumofore sincesliding movement of vanes inside the slots of 2007. His technicalthe rotor. The total contact surface between education and intensethe edge of the vanes and cylinder is much commercial experiencesmaller than the total contact surface make him a successfulbetween the two screws between them and manager and member of thethe inner surface of the cylinder. When the Pneumofore Council. Therotary screws come to the end of their life they hollow glass industry is one ofmust be replaced bringing a significant repair his strong application fields,cost. A rotary vane pump can be also due to his continuousdisassembled and, after re-polishing the presence at relatedcylinder, will deliver again the original worldwide conferences andperformance. fairs. Direct contactPneumofore offers a wide range of rotary ferrero@pneumofore.comVia N. Bruno, 34 - 10098 Rivoli (TO) - ItalyTel. +39.011.950.40.30 - Fax +39.011.950.40.40info@pneumofore.com - www.pneumofore.com Trademark and logo Pneumofore® are registered worldwide. It is7/20en sep11 strictly forbidden to make unauthorised copies of this document. © Pneumofore S.p.A. - all rights reserved

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