Zpracování odpadů z výroby papíru a celulózy

Processing of wastes from pulp and paper plant

report

Czech

Tato výzkumná práce se zabývá problematikou zpracování kalů vnikajících při výrobě papíru a celulózy. Jedná se zejména o jejich využití v zemědělství, skládkování a nebo jejich termické zneškodnění. Na základě rozboru způsobu využití kalů v zemědělství a předpokládaných trendů, které jsou naznačeny v publikaci, je hlavní pozornost směřována na oblast termického zneškodňování kalů, které bude v budoucnosti hrát výraznou roli v tomto oboru.

Production of sludge as waste in pulp and paper plants can be considered as one of serious environmental problems which have to be solved. Landfilling is not a suitable way from the environmental point of view. A thermal treatment process proved itself to be the most appropriate solution. This paper shows an efficient way how to process the sludge including waste to energy aspects. A thermal treatment unit with a capacity more than 100 tons of wet sludge per day had been built in one large pulp and paper plant some years ago. This pulp and paper plant is located in mining area. When built, this unit was quite modern. However, because of more and more sweeping environmental laws affecting the process industry, the unit needed a complete retrofit. The retrofit has been realized in three stages. A brief description of the unit for the thermal treatment of sludge is as follows: The waste sludge (after a transport from a sludge storage system) is burnt in a multiple hearth incinerator with a fluidized-bed chamber. Then the flue gas enters a secondary combustion chamber (afterburner chamber). During the first stage of retrofit only a part of heat from flue gas was utilized for heat recovery (pre-heating air for combustion and fluidization) and a contact cooler was involved into the unit. The second stage of retrofit can be characterized as a waste-to-energy one. The contact cooler was replaced by a system for preheating water for steam generation. Off-gas cleaning system consists of a filter for particulate removal and a three stages scrubber system. (Several alternatives of retrofit were considered and simulated and the most promising one was selected.) The third stage of retrofit consists in substituting the currently used fuel by mining gas containing approximately 50 to 60% of CH4. Utilizing this waste gas represents an important contribution from both environmental and economic points of view. Last but not least removing the gas from mines decreases risk of creating an explosive mixture with air and thus it is also important from safely reasons. The unit for thermal treatment of sludge after retrofit can be considered as one of the most up-to-date incinerators with waste-to-energy system at present. A comparison with landfilling has been performed including economic and environmental evaluation.

pulp, sludge, paper plant,

ORAL, J.; ŠIKULA, J.; PUCHÝŘ, R.; HAJNÝ, Z.; TRUNDA, P.; STEHLÍK, P.; BÉBAR, L.; MARTINÁK, P.

1. 11. 2002

VUT Brno

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