Dry Ice Expanded Tobacco In Demand

Source from:  Tobacco Asia 05/12/2010

Airco DIET is experiencing a massive interest in new DIET facilities worldwide as the demand for Dry Ice Expanded Tobacco skyrockets. Airco DIET has supplied close to 55 DIET plants worldwide and is a household name for high expansion within the tobacco industry. The DIET process itself was invented and patented as a joint venture between Airco DIET and Philip Morris and today all major players in the cigarette industry own DIET plants. Dry Ice Expanded Tobacco (DIET) is a key element to meet today's challenge to produce superior tasting and performing products in a cost-sensitive environment. Furthermore DIET provides great control over critical finished cigarette parameters and provides taste benefits that cannot be achieved with the use of any other expansion processes. The DIET process is an effective tool for tar and nicotine reduction in cigarettes using tobacco laminar; it also reduces the bulk density of the cigarette blend which significantly reduces the cost of manufacturing with utility production costs of less than €1/kg (US$1.38/kg) of produced DIET tobacco. Today's inclusion rate of DIET in premium cigarettes is therefore also 20% to 30%. DIET provides product designers and developers a true tool with which to achieve desired cigarette taste, quality and delivery properties. How does it work? After the green tobacco is harvested it is cured and during the curing process the cellular structure in the tobacco leaf collapses and the volume of the tobacco is greatly reduced. The DIET process uses the unique thermal and physical properties of carbon dioxide to expand tobacco and a net volume increase of about 110% to 140% at target moisture is realized. The volume increase is achieved by bringing the cellular structure in the tobacco leaf back to the original stage. The process can shortly be explained as follows: cut tobacco is submerged in liquid carbon dioxide under high pressure conditions in a pressure vessel known as an impregnator. CO2 is an excellent solvent and the liquid CO2 penetrates the tobacco cells instantly. After a brief soak period, the liquid carbon dioxide is drained to the process tank and reused. Carbon dioxide gas remaining in the impregnation vessel is recovered by compression and condensation and returned to the process tank to be used again. The only CO2 consumed is the about 8% bound in the tobacco. When the pressure in the impregnator is reduced to atmospheric, the residual liquid carbon dioxide in the tobacco cells turns to dry ice. The frozen tobacco is fed to a declumper to produce a flowing constituent that is metered into the re-circulating hot gases of the sublimator tower. When heated, the frozen carbon dioxide in the tobacco cells sublimes and increases in volume more than 100,000 times. The resulting internal pressures inflate the tobacco cells to provide a volume increase, typically around 110%-140%. The expanded tobacco is removed from the sublimator by a tangential separator and reordered to restore the moisture to target, normally about 12%. DIET plants of 570, 1140 and 2,280kg/hr have been available for the last 25 years. However, due to strong demand, particularly from smaller manufactures, Airco DIET developed a small 300kg/hr DIET plant last year which is now also available in a low-cost solution. A couple of 300kg/hr DIET plants are already sold and the demand appears to be solid for the next several years. The 300kg/hr DIET will produce more than 2 million kg of DIET tobacco a year so the cigarette manufacture would still have to be of a considerable size to sustain even this small DIET plant. The availability of a mini DIET plant provides a whole new second tier of manufactures the opportunity of investing in a DIET facility which was previously reserved for a few very large manufactures. An added benefit for the smaller plants is a significant improvement in delivery time: where a normal size DIET plant requires 12 months from ordering to delivery, a small DIET plant can be delivered in only nine months. The installation time is also shorter, so a small plant can be up and running in seven to eight months, faster than a regular large DIET plant. Independent DIET tolling facilities are a part of this second tier of new DIET plants and they are able to provide a superior DIET product to even the smallest manufacture; such tolling facilities are being installed in Bangladesh for Dhaka Tobacco and in Indonesia for RMI. Significant changes The first DIET plants were built by Airco DIET 30 years ago in 1987 but these first plants where significantly different in design even though the basic process remains the same. The DIET plants have evolved radically over the years and there have been significant improvements introduced. A modern DIET plant has an uptime above 95% with a DIET dry weight yield above 98.5%. The utility requirements have at the same time been significantly lowered making the DIET plant even more profitable for the manufacture. The constant increase in the cost of tobacco leaf together with a customer demand for white and lighter cigarettes spreading to the developing markets continue to insure a strong demand for Dry Ice Expanded Tobacco throughout the industry and Airco DIET is standing strong to fulfill the market demand with its many years of product development together with an unmatched track record of DIET plants throughout the world, meeting both customer demands as well as local rules and regulations.

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