Co-Combustion of Tire Pyrolysis Products and Wood Pellets

Thermal power plants remain one of the main sources of environmental pollution. The deterioration of the quality of traditional carbon-containing energy resources leads to the need to develop technologies for co-combustion of biofuel and coal at small and large power plants. The paper proposes the concept of using solid waste from tire recycling by adding to the composition of the mixed fuel “coal – wood waste” as a substitute for coal slag, which is formed during the utilization of worn-out tires by pyrolysis. The aim of the work was to determine the possibility of increasing the calorific value of wood pellets by co-firing with pyrolysis slag instead of coal without increasing the burden on the environment. At the same time, the following tasks have been set: to determine the lowest combustion heat of mixed fuels and assess its change when replacing coal with slag; to determine moisture content, total sulfur content, volatile matter yield, ash content of mixed fuels according to standard methods; to assess the change in these parameters when replacing coal with slag at the same component ratios; to determine the optimal ratios of components in mixed fuels, which will not increase the burden on the environment when replacing coal with pyrolysis slag. It has been determined that replacing coal with slag results in an increase in calorific value by 37–45 %, a decrease in ash content by 37–42 %, and an increase in the yield of volatile substances. At the same time, the sulfur content increases by 5.6–18 %. The use of traditional cleaning equipment is recommended in order to reduce the emission of sulfur dioxide. The research results make it possible to substantiate the possibility of replacing coal with slag in mixed fuels at certain ratios of components. A new direction of using solid products from recycling of rubber products, i.e. worn-out tires, has been proposed by the pyrolysis method in mixed fuels “slag-wood pellets” for small and medium-sized power plants.

Preparation of hydrogen-rich gas by catalytic pyrolysis of straw-plastic mixture with nickel-based honeycomb cinder

Nickel catalyst supported on honeycomb cinder (Ni/HC) was prepared by a homogeneous precipitation method. The catalyst was applied to produce hydrogen-rich combustible gas by catalytic pyrolysis of soybean straw and plastic (PE) mixture. The straw and plastic materials were analyzed by elemental analysis and industrial analysis. The support and catalyst were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherm (BET). The analysis showed that NiO was well loaded on the surface of honeycomb coal slag carrier. The effects of Ni loading, pyrolysis temperature, holding time, and calcination temperature on the experimental results were studied. The results showed that the preparation of the catalyst was feasible and that it had a good catalytic effect. When Ni loading was 15 wt.%, catalytic pyrolysis temperature was 700 °C, holding time was 20 min, and calcination temperature of catalyst was 400 °C, H2 concentration increased from 20.6 to 52.8 vol.%, and while H2 yield was 302 mL/g, CH4 concentration decreased from 51.1 to 22.6 vol.% and CO concentration increased from 10.8 to 17.8 vol.%. After the catalyst was regenerated 6 times, the H2 concentration still reached 40 vol.% and the combustible gas concentration was still above 80 vol.%. The catalyst still had good catalytic activity.

Influence of Type of Secondary Raw Material on Consistency of Fresh Mixture for AAC Production

Autoclaved aerated concrete (AAC) is, mainly in Europe, widely used construction material. It has an optimal combination of bulk density, strength and thermal conductivity coefficient for load-bearing and non-load-bearing structures of civil facilities. The production technology is based on a mixture of ground silica sand, lime, cement, gypsum, aluminium powder and additives. The grinding of sand is most often carried out in a wet way, and the sand sludge is consequently used in production technology. The aim of the experiment was verification of the effect of partial replacement of sand with the alternative raw materials in sand sludge on the rheology of the mixture. This parameter determinates how the modified mixtures affect the sludge pumpability. As a reference the consistency of the sand sludge of the normal production density of 1.65 g/cm3 was compared to the sand sludges of different density (1.60, 1.70 and 1.75 g/cm3) and with a fresh aerated concrete (FAC) mixture of 1.60 g/cm3. Then the sludges were modified by 30 % of alternative raw materials (recycled glass, coal slag, FBC ash, FBC bottom ash) as the partial weight replacement for sand. This partial replacement resulted in water/solids ratio adjustment which recommended value is 0.47 for recycled glass and coal slag, 0.59 for fluidized bed combustion (FBC) bottom ash and for FBC fly ash it is 0.70.