Biomass

Biomass: defined as plant materials and/or animal waste used primarily as a source of fuel. Today, with energy costs a worldwide concern, biomass is being viewed as an increasingly interesting alternative fuel for use in industry. New legislation with regard to land-fill, as well as increased costs for transportation could lead to innovative waste management solutions for the future.

Biomass can be derived from such sources as:

• Sludge from municipal and industrial waste water treatment, bark or wood waste can be processed for more efficient use as fuel to produce heat and power.
• Fibrous sludge from the forest industry (from de-inking recycled paper and sewage sludge), which contain biomass along with fibres.

However, the high water content in biomass presents a challenge, for even after advanced mechanical de-watering, the sludge still contains 60 - 80% water. To incinerate a fuel with such high amount of water reduces the net heat generated by a boiler, and at approximately 80% water content, the net heat is reduced to nil since all of the heat value is consumed in the furnace to evaporate the water. Another drawback is design of boiler and flue gas treatment. These have to be oversized to cope with large volumes of water vapor.

GEA Barr-Rosin, with over 25 years of expertise in drying technologies, and a division of the GEA Group, whose head offices are situated in Germany, is proud to present an energy efficient drying solution in its exclusive Superheated Steam Dryer (SSD™). The SSD™ is an indirect heated pneumatic dryer where water in the product produces steam at 0.5 to 4 barg pressure. As there is no air or flue gas in contact with the product, no emissions to the atmosphere are produced. As indirect heating media, boiler steam, flue gas, thermal oil or even hot water can be used.

In comparison to open type dryers the SSD™ consumes less gross energy (about 1,280 BTU/lb of evaporated water). By recovering the heat in the evaporated water (steam), about 1,025 BTU/lb can be recovered.

Sludge, bark and wood waste as referred to above, can be dried to 90-95% dryness before use as fuel. This results in a maximum and stable production of heat from the boiler, which can be used for heating as well as power production in a steam turbine. Only part of the steam will be used for heating the SSD™, of which about 80% will be recovered by using the generated steam from the dryer in the pulp and paper process.

GEA Barr-Rosin presents a number of feasible solutions for process integration of the Superheated Steam Drying system and economics for some case studies.

GEA Barr-Rosin could help you to optimize the overall efficiency of your plant (pulp and paper, sawmill/wood pellet/co-generation) by drying biomass prior to burning it in a boiler, or pelletizing it to produce hog fuel.

Superheated Steam Drying (SSD™)

The SSD™ technology can easily dry all types of biomass, i.e. wood chips, sawdust, bark, primary, secondary and deinked sludge with the highest efficiency drying process.

The heating source for the dryer could be either high pressure steam (ideally between 11 and 25 barg) or high temperature flue gas (1,100 - 1,600 °F). High temperature flue gas could be produced by a biomass burner or gasifier.

A further option would be to use a portion (25 - 35%) of the dried biomass coming out of the dryer and burn it in a biomass burner to generate high temperature flue gas.

Key features of SSD™ dryers are:

• Superheated Steam
• Pressurized atmosphere
• Closed Loop
• Low energy consumption
• Indirect heating

Foremost benefits of SSD™ dryers are:

• No emissions
• No air treatment equipment needed (RTO or TO, ESP or Scrubber)
• High exact dryness
• No risk of fire / explosion
• Small footprint
• Cooking / sterilization

In addition to the described Superheated Steam Dryer (SSD™) GEA Barr-Rosin can also provide ring dryers, rotary dryers, fluid bed dryers, and flash dryers to dry any type of biomass.