Pulp Paper & Logistics
ANDRITZ 17
to pay a small premium for the ‘premium quality’ produced. In many regions, there is a strong reluctance to accept this requirement and, as such, it becomes difficult to justify the levels of investment and historically, ROI calculations have thus been unattractive.
Stefano Marenco: “focusing our research on technical solutions that can increase the overall efficiency of the TAD machine with a more compact design”
A number of the technologies
have been specifically developed for the TAD product. These include the 3-layer headbox, the TAD drums and their air-systems, the active foils and the centre-wind reel. Additionally, the C-wrap had to be modified to allow the use of vacuum assisted dewatering in the former.
When we first started down
this route, we typically offered a single large diameter TAD drum but have since developed our standard machine to the two- drum arrangement to optimise the energy efficiency of the process for our customers.
What challenges do customers face when producing premium quality tissue? Joe Guadagno: The biggest challenges for most newcomers to the TAD business are the levels of complexity of the process, compared to conventional tissue making. That of course, plus the fact that the machine is more than twice as long as, and therefore more expensive than, a standard light dry crepe (LDC) tissue machine. The level of papermaking competence required is high and the personnel with experience are not as readily available on the employment
market as for, say, LDC production. Moreover, the TAD side of the tissue industry is particularly secretive, with all manufacturers carefully guarding their know- how. This means movement of personnel from one manufacturer to another often will have contractual obstacles or barriers to making a new start. A second issue for TAD is the
overall bulk of the machine. This is the biggest advantage for TAD but means that transportation is a potential cost problem. TAD needs to be produced close to the market to avoid transporting high bulk, low weight materials, when shipping costs can start to seriously influence overall production costs. The other big issue for TAD producers is the overall energy demand. Through- air-drying uses a large amount of thermal energy, which is typically generated using gas burners. In many regions of the world, the infrastructure cannot support such demands and so alternatives would be needed. In theory, just about anybody
could produce TAD if they already have some papermaking experience: it is more a question of having a suitable market for the final product. To be attractive, the customer needs to be willing
Who would be the ideal customers that would benefit from this technology? Joe Guadagno: The ideal customer needs to already have a good basis for operation. It must not necessarily be in tissue, although this helps to ensure there is a trained workforce available. The process is bigger than conventional LDC and needs more personnel to work the machine from pulping to reel. Although the product is not very heavy for the roll size, the frequency with which the parent rolls leave the machine require an investment in roll handling to ensure rolls are swiftly processed and fed to converting. Such customers also need a sound awareness and experience of the converting of tissue. It makes no sense economically to ship paper to a converting plant and have it converted off-site. Key personnel with operational capabilities, especially in the area of controls and automation, together with dedicated
maintenance resources with proper levels of materials (spare and wear parts) will ensure the process is kept running at the highest efficiency. Given the foregoing, the ideal
customers are those that already have such operations, but everybody has to start somewhere and Andritz – based on its long-term expertise with TAD technology – can support through this complete development phase (when the machine and process are brought into commercial operation) with know-how, equipment, training, assistance, and services.
What are the details of the technology (the hood and air system) and what sets the PrimeLine TAD concept apart from competitors? Joe Guadagno: The TAD Hood and Hot Air System consist of important equipment that defines the TAD system’s thermal drying process. All components must be carefully selected and optimised to allow the TAD drying process to operate efficiently through the range of parameters needed for tissue and towel grades. The process air system is used
to transport hot air through the paper sheet with a uniform temperature and pressure profile. There are different ways to
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Paul Richards: “One of the key areas of interest in this technology is clearly a reduction of the drying energy”
July/August 2021
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