Production of tissue requires industrial energy gas
In tissue production, the energy use for drying is considerable. Modern tissue drying processes utilize direct fired, high temperature, drying hoods where the flue gases from LPG or natural gas combustion are blown towards the wet tissue paper.
The quality demands on tissue paper are high; visual imperfections or odors caused by particles originating from the flue gases are unacceptable.
Combustion of fossil gases used to generate the process heat is the main source of greenhouse gas emissions within the paper industry. Alternatives to the fossil gas has not been available due to the combination of demand on costs and quality over time. Tissue production is generally on 24/7 operations and cannot risk any production hick-ups due to variety in heat quality.
The tissue making process
The common tissue making process starts with dissolved pulp that is distributed (sprayed) onto a felt and formed into a sheet. Due to capillary forces the fibers sticks to the felt and gets transported to the first part of the drying where water is pressed out, the pulp is transferred to the Yankee cylinder and the felt returns to pick up new pulp. The Yankee cylinder is a big cylinder which is heated from the inside, most commonly by hot steam. The pulp is passing through the drying hoods, where hot air, generated from combustion of fossil gas, dries the tissue. Next step is the creping section where the tissue is scraped from the yankee cylinder and creped, i.e. generating the thickness and fluffy characteristic for tissue. Last step is the reel up of the jumbo rolls. In a tissue converting process the jumbo reels are then cut and packed (e.g. to napkins, toilet paper, household paper etc.) before being sent to the tissue consumers.
The emissions of one single tissue mill
Changing to renewable gas for one tissue mill (80 000 MWh LPG)
– How much CO2-emissions are spared?
The trend is clear - gas is the future for tissue drying
Tissue producers and machine suppliers are united:
– Combustion of gas is the tissue drying method for the foreseen future.
Other solutions, like electrical dryers cannot meet the requirements of high process temperatures and quality in combination with low cost.
In fact, several machine suppliers look into new solutions which increase in gas consumption. For instance, circulate heat generated in the drying hood into the yankee cylinder – eliminating the need of steam, or upgraded Through-Air-Drying solutions etc.
The need of renewable alternatives is therefore acute and increasing.
According to a recent market study conducted by consultancy firm BCNP, the total consumption of gas within the paper industry is today 84 000 GWh. That is a market value of about EUR 3 bn