According to the European Parliament and Council, chicken manure can be used as fuel in situ as a promising energy source. This study shows the characteristics of the combustion process, which uses a mixture of chicken manure with straw or wood (sawdust) in terms of thermal self-sufficiency in poultry farms.
1 . introduce
For many years, various types of biomass have been used as additives or alternatives to coal or oil for heat and power generation. Combustion tests have been carried out on different types of biomass, including wood, straw, sunflower shells, bamboo, refuse-derived fuel (RDF), and other wastes. Considering the growing poultry production, the use of chicken manure as a fuel for heating and power generation, especially for the poultry farms themselves, is becoming more cost-effective.
The largest poultry producers in Europe are Poland, the United Kingdom, France, Spain, Germany and Italy, with Poland leading the way, with total poultry production reaching 192.1 million in 2017. According to the literature, the amount of poultry manure per 1000 chickens can reach 65 kg/day for broilers, 160 kg/day for turkeys, and about 200 kg/day for geese and ducks. Such a large amount of chicken manure can lead to problems with its control disposal, especially its storage. Long-term application as soil fertilizer or contact with soil during storage can lead to phosphate and nitrate contamination of surface water bodies. In addition, storing chicken manure near a chicken farm poses a risk of contamination for new batches of chickens.
According to the literature, the utilization of chicken manure can be successfully carried out by anaerobic digestion, pyrolysis, or co-digestion processes. Biomass gasification. However, it is worth noting that according to the regulations of the European Parliament and of the Council (EU 2017/1262), chicken manure could be another promising energy source that could be used as fuel for the combustion process on the farm site. For this reason, the combustion process of poultry manure has become a research topic.
Adamczyk et al. performed an analysis of the combustion process in a fluidized bed reactor, including the characterization of ash content. Studies have shown that poultry manure granulation improves the efficiency of the combustion process and the chemical properties of the ash. Chowdhury et al. The characteristics of the poultry bedding combustion process in a fluidized bed reactor are also presented, and a life cycle assessment is provided to characterize the efficacy and sustainability of the combustion process in terms of heat and power generation. Polesek-Karczewska et al. also analyzed the burning of poultry manure. He reported on an experimental study of mixed poultry litter with straw burning. In turn, Junga et al. have proposed research using thermogravimetric analysis techniques. The combustion behavior of layer manure was analyzed, and Atimtay and Yurdakul were analyzed for mixed combustion of baked poultry litter with lignite. The results showed that the roasting process had an important influence on the decomposition temperature, and the decomposition temperature increased with the increase of the roasting temperature.
The main litter used for laying hens is straw. Wood chips, shredded paper, and pellets are used less frequently. Sawdust bedding is an increasingly popular solution on farms. The amount of straw or wood chips is usually 2 to 5 kg/m2. After a 6-7 week cycle, the final poultry litter contains about 62% manure, 31% litter, 3% waste feed, 2% feathers, and 2% foreign matter. As the chickens rummage on the ground, the coop is filled with garbage that can show their natural behavior.
According to the literature and data obtained at the Kczewo poultry farm in northern Poland, the mixture obtained after one poultry farming cycle consists of 90% chicken manure and 10% biomass waste (in terms of dry matter). thing). In the normal operating cycle, an area of 3000m2
of chicken farms (enough to raise about 50 000 chickens) produce about 100 tonnes of wet manure mixed with litter. An important step in the use of manure as fuel to meet the farm's own needs is to characterize the combustion process based on the base material (straw, sawdust) and its content in the manure.
This work describes the possibility of using chicken manure in the on-site combustion process, leading to waste management in a circular economy, in this case thermal self-sufficiency of poultry farms. The presented results provide important guidance for the characterization of combustion pellets consisting of a mixture of chicken manure, straw and wood, as well as for the caloric analysis of waste streams generated in typical poultry farms. The experimental results show the effect of the mixture composition on the average and maximum combustion temperature and the flue gas composition. In this work, the characteristic parameters of thermal degradation, the treatment of chicken manure in air, and the analysis of the content of inorganic compounds in the ash of chicken manure combustion were also proposed
2 . Materials and methods
2.1 . material
Chicken manure samples were taken from one of the largest chicken farms in Kčewo, Poland. In order to carry out experiments on the combustion process, a representative mixture is first dried, and in order to determine the effect of chicken manure content on the combustion process, experiments are carried out on a fuel mixture of wood or straw and chicken manure. The mass levels of stool in the samples were 50%, 70%, 80%, and 90%, respectively.
2.2 . Industrial analysis and final analysis
The results of industrial analysis and elemental analysis of the materials used in the experiment are shown in Table 1. For analysis, the provided sample is first dried and then ground in a centrifuge with a 0.2 mm perforated plate. The moisture content was determined using a moisture analyzer (RADWAG). The calorific value is determined using a calorimeter (KL-11). Elemental composition was determined using an elemental analyzer (CHNS-O Flash 2000, Thermo Scientific) and an X-ray spectrometer (WDXRF Bruker Scientific Instruments).
3 . Results & Discussion
3.1 . Thermogravimetric analysis of chicken manure
Figure 2. The rate of mass loss during thermogravimetric analysis of waste from samples in air
3.2 . Temperature characteristics
The samples used contained 50%, 70%, 80% and 90% manure by mass and were found to have a decrease in bulk density from 435.4 kg/m3 for chicken manure alone to 318.10 kg/m3 for a 50/50 manure and wood mixture and 391.86 kg/m3 for a 50/50 manure and straw mixture.
The average maximum temperature (T MAX) obtained when the mixture of chicken manure with straw or wood is burned has a similar value of about 1000°C.
Figure 3. Characteristic temperature of straw and chicken manure pellet combustion
Figure 4. Characteristic temperature at which wood and chicken manure pellets burn
Figure 5. The rate of mass loss of the fuel mixture during combustion
3.2.1 . Flue gas analysis
Figure 6. NOx emissions during the combustion of different samples
Figure 7. Sinter is formed on the reactor grate, forming a mixture of manure and straw pellets 50/50.
4 . conclusion
The properties of chicken manure and experimental results show that this fuel is difficult to burn alone. The experimental results show that adding only 10% straw or wood can improve the combustion process, and the output power (65 kW) can meet the heat demand of the farm (40 kW) and enable the farm to carry out waste management in a circular economy.
However, the use of large amounts of straw in the mixture can increase NOx emissions, reduce power density (Pρ), lower temperatures, and operational problems of incinerators and heat exchangers associated with ash sintering. This effect was not observed when sawdust was added.
Detailed combustion analysis shows that the hemispherical temperature (1040 °C) and spherical temperature (1120 °C) of straw ash are significantly lower than those of pine ash (1200 °C and 1220 °C).
Although the maximum temperature is similar for all mixtures (about 1000 °C), the flame temperature increases with the proportion of additives in the mixture, from 600 °C to 800 °C (straw), 900 (wood). The increase in the temperature of the flame is due to an increase in the content of volatiles in the fuel, which leads to a more developed flame. A small amount of additives in the mixture reduces NOx emissions, but the reduction is even more pronounced for wood (up to 280 mg/m3).