Improving the Efficiency of Using Plywood Production By-Products

To use plywood production waste to generate energy ensuring the operation of the non-public limited liability company “SVEZA Ust-Izhora” a mini-heat-and-power plant with 2 Е-40-2.25-305ОP boilers and a turbine has been installed. A 2-stage ash clearing of combustion products has been provided. The 1st stage ensures the removal and return of coarse fractions to the vibrating grid. At the 2nd stage, the products pass through bag filters. An energy inspection of the boiler units has revealed that the gas cleaning system is the cause of their frequent shutdowns and starts, additional heat losses and a reduction in the equipment life cycle. In this regard, instead of bag filters, a dust and ash collection complex (KPZU-10×6×2) has been installed. However, the degree of solid particle capture by the complex has been no more than 80 %, ash has been observed sticking to the impeller of the smoke exhauster, which has caused and imbalance and a reduction in the life cycle of the smoke exhauster and the need to stop the boiler at least once a week. The aim of this article has been to establish the reasons for the increased emissions of solid particles and carbon monoxide, the limited period of operation of the boiler unit between cleanings, as well as the lack of the possibility of prompt removal of ash and slag to the landfill. A comprehensive analysis of the boiler unit operation has been carried out on the basis of the operational and environmental performance indicators of the boiler, thermal engineering and granulometric characteristics of samples of the combusted biofuel and the resulting focal residues, as well as their elemental composition and thermogravimetric characteristics for plywood chips. The modernization of the gas cleaning complex has ensured the functioning of the boiler with a nominal steam capacity and has reduced the number of its stops between cleanings by 7–21 times. However, the use of a boiler with a higher capacity has lead to an increase in the polydispersity of fly ash and the content of combustible substances in it, which has become one of the reasons for its smoldering in the collection container. Periodic switching on of the vibrating grid has resulted in significant instability of environmental indicators. A study of the polluting potential of plywood scrap ash has found it to be the most powerful polluting component in the combusted mixture. The study of thermal processes in plywood chips in air and inert environments has shown a noticeable influence of the presence of glue based on phenol-formaldehyde resin.