Poultry Litter Gasification Research Articles

Hydrogen prediction in poultry litter gasification process based on hybrid data-driven deep learning with multilevel factorial design and process simulation: A surrogate model

Gasification is one of the recommended processes for poultry litter valorization, and its success is largely dependent on process input parameters for syngas production. The quality of syngas, characterized by a higher heating value (HHV) and lower heating value (LHV), is significantly influenced by hydrogen. In this research, integration of Aspen Plus simulation and Convolutional Neural Network (CNN) have been done to estimate the hydrogen content in syngas. The gasification process has been optimized using the response surface method, and the results have been supported by the particle swarm optimization (PSO) technique. The statistical analysis of the response surface model revealed that the optimal process parameters are around 408 °C, 2.0 (biomass to air ratio) BMR, and 2.0 bars. Interestingly, PSO led to nearly identical optimum values (400 °C, 2.0 BMR, and 2.0 bars), resulting in high-quality syngas. Furthermore, CNN exhibited a good predicting performance with a coefficient of determination (R2) exceeding 0.96, coupled with mean square error (MSE) and mean absolute error (MAE) of 0.01 and 0.05, respectively. This solidifies the integration of Aspen Plus simulations and CNN as an accurate surrogate model for predicting hydrogen levels during poultry litter gasification, enabling effective process optimization. Therefore, the proposed model serves as a reliable tool for predicting and optimizing the syngas produced during the gasification process of poultry litter, with potential applications in enhancing energy production and waste management practices.

Transformation of inorganic matter in poultry litter during fluidised bed gasification

This work investigates the transformation, release and fate of inorganic matter during fluidised bed gasification of poultry litter and also poultry litter mixed with limestone as an additive. The poultry litter, the cyclone and bed ash were characterised by means of chemical fractionation analysis, as well as X-ray diffraction. Concurrently, the release of inorganic species during gasification of the feedstock was measured in separate laboratory experiments using molecular beam mass spectrometry. In addition, FactSage was used to predict the formation of gaseous species and the composition of solid residues from gasification under equilibrium conditions. On average, the cyclone ash accounts for 4.6 wt% and the bed ash 12.4 wt% of the total poultry litter fed into the reactor. All phosphorous (P) was present in the cyclone ash as stable phosphates, while potassium (K) in both cyclone and bed ash was mainly present as H2O leachable KCl, organically associated and stable phosphates and silicates. Furthermore, an assessment was made against the appropriate criteria, whether the ashes from gasification can be categorised as component materials for EU fertiliser products.

Experimental investigation of poultry litter gasification and co-gasification with beech wood in a bubbling fluidised bed reactor – Effect of equivalence ratio on process performance and tar evolution

The effect of equivalence ratio on gasification of poultry litter, blend of poultry litter with beech wood and beech wood alone, was experimentally studied in a lab-scale fluidised bed reactor. Lower calorific value decreased with equivalence ratio whereas carbon conversion efficiency revealed the opposite trend. Beech wood showed both the highest lower calorific value and carbon conversion efficiency, 4.96 MJ/m3 and 91.6% respectively. Total gas chromatography-detectable tar decreased with an increase in equivalence ratio. The reduction in total gas chromatography-detectable tar was more profound in the case of poultry litter (22%). Beech wood illustrated the highest amount of total gas chromatography-detectable tar, 7.52gtar/kgfeedstock-daf at the lowest equivalence ratio, due to the higher lignin content responsible for generation of polycyclic aromatic hydrocarbons. Agglomeration occurred while gasifying poultry litter at 750 °C and at the highest equivalence ratio (0.25), whereas in the case of blend and beech wood alone all the test runs were conducted successfully.

Modeling the valorization of poultry litter via thermochemical processing

AbstractWaste management via thermochemical processing is gaining increasing importance as larger volumes of solid waste are generated yearly. The poultry industry generates a variety of wastes, of which the largest stream in terms of volume is the litter. In this study, three thermodynamic models were developed on ASPEN Plus v8.8 for pyrolysis, in‐line steam reforming, and gasification of poultry litter. At optimal pyrolysis of 450 °C, the product yield was 43.74 wt% bio‐oil, 6.71 wt% gas, and 49.55 wt% char. The optimal conditions for the in‐line steam reforming of poultry litter were observed to be 400 °C temperature and 12 kg kg−1 steam‐to‐feed ratio (STFR), yielding a syngas composition of 70.2 mol% H2, 29.4 mol% CO2, 0.22 mol% CH4, and a trace amount of CO. The optimal conditions for the gasification of poultry litter were 700 °C temperature and 0.2 kg kg−1, yielding a syngas composition of 52.6 mol% H2, 10.3 mol% CO2, 2.77 mol% CH4 and 34.3 mol% CO. Gasification gave a higher syngas yield but with less quality. Steam reforming gave better quality but a lower yield. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd

Gasification of poultry litter in a lab-scale bubbling fluidised bed reactor: Impact of process parameters on gasifier performance and special focus on tar evolution

Poultry litter (PL) gasification was experimentally investigated using a lab-scale bubbling fluidised bed reactor. Characterisation of the gasification process was performed in terms of yields and compositions of both gas and tar, lower calorific value (LCV) of the product gas, cold gas efficiency (CGE) and carbon conversion efficiency (CCE). Experiments were carried out at different temperatures (700–750 °C) and equivalence ratios (ERs). The effect of gasifier temperature at a constant ER of 0.21 shows that an increase in temperature improved the gasification process performance whilst the total tar content decreased, implying that higher temperature enhances the conversion of biomass to product gas. The total gas yield increased from 0.93 to 1.24 N2-free m3/kgfeedstock-daf, LCV increased from 3.38 MJ/m3 to 4.2 MJ/m3, while the tar content was reduced by 24% (5.6–4.25 gtar/kgfeedstock-daf). The detailed analyses of tar compositions reveal that styrene and xylenes were the most abundant compounds in the secondary tar group. Moreover, naphthalene and 1, 2-methyl naphthalene were the dominant compounds found in tertiary polycyclic aromatic hydrocarbons (PAH) and alkyl tertiary groups, respectively. Furthermore, at the highest tested temperature of 750 °C and ER of 0.25, bed agglomeration took place causing the shutdown of the gasifier. The defluidisation of the bed occurred due to the high ash content of PL comprising of low melting temperature alkali compounds. The results obtained from this study showed the performance and potential challenges associated with gasifying PL in a fluidised bed reactor for the combined heat and power production at farm level.

Environmental and economic sustainability of poultry litter gasification for electricity and heat generation

This work aims to assess the environmental and economic sustainability of poultry litter gasification for heat and electricity generation. The results are compared with gasification of two other biomass feedstocks (Miscanthus and waste wood) and energy from fossil fuels. The findings suggest that poultry litter gasification can lead to significant reductions in 14 out of 16 impacts considered in the study in comparison with fossil-fuel alternatives. Compared to combined heat and power (CHP) from natural gas, most impacts from gasification of the litter are lower by more than 90%, including global warming potential. However, human toxicity and depletion of minerals are 25% and three times higher, respectively. Energy from poultry litter also has lower impacts than from waste woodchips and Miscanthus across all the categories, except for acidification. Owing to high capital costs, the unsubsidised cost of generating heat and electricity from poultry litter is similar to that of natural gas CHP but significantly cheaper than from other fossil-fuel alternatives. However, with the current subsidies in the UK, the payback time for poultry litter gasification is 13.5 years. It is estimated that 4.55 Mt of poultry litter is currently available in the UK, 2.73 Mt of which is suitable for conversion to energy. If this waste is utilised in gasification plants, it could potentially provide 0.6% of electricity and heat in the UK and save 1.7 Mt of GHG per year, equivalent to around 0.4% of UK’s GHG emissions. However, the successful uptake of this technology will depend on a future reduction in capital costs.

Fly Ash From Poultry Litter Gasification – Can it be Utilised in Agriculture Systems as a Fertiliser?

Fly ash from a poultry litter gasification process and the potential of application of the fly ash as a fertiliser in line with the poultry litter protocol is investigated. The fines collected in the cyclone are mainly formed by ash which comprises between 70-83 wt.% of the fines on a dry basis, and to a lesser extent of carbon (elutriated char). The effect of the gasification operating conditions on the concentration of ash forming elements (inorganic compounds) in the fly ash, are discussed. In addition, the enrichment factor which defines the volatility, has been used and fly ash elements were categorised as Class I (non-volatile), Class II (semi-volatile with the possible occurrence of condensation) and Class III (highly volatile elements). Inorganic elements in fly ashes from poultry litter gasification experiments are categorised as Class I: Ca, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Class II: Cd, Cr, Mo and Class III: Pb and Se. It has been found that the fly ash from the poultry litter gasification exceeds the upper acceptable limit set by Poultry Litter Protocol to be used as a fertiliser in agriculture systems.

Environmental impacts of poultry litter gasification for power generation

The poultry industry generates a large quantity of litter, which consists of a mixture of manure, waste bedding and feathers, and can be used for recovery of energy. Recent studies suggest that gasification is a promising technology for an effective conversion of poultry litter to energy. This paper aims to assess the environmental impacts of generating electricity from the gasification of poultry litter in a small-scale integrated gasification combined cycle (IGCC) plant. Gasification of poultry litter has been simulated with ASPEN Plus® software and life cycle assessment has been used to determine the carbon footprint and primary energy demand of the system. The following life cycle stages have been considered: collection and storage of poultry litter, its gasification, syngas cleaning, production of electricity and co-production of ash as a fertiliser. The carbon footprint and primary energy demand of generating 1 kWh of energy by poultry litter gasification plant are estimated at 42 g CO2 eq./kWh and 0.14 MJ/kWh, respectively. Compared to electricity from fossil fuels, this system has 91%-96% smaller carbon footprint and 98%-99% lower primary energy demand. The energy payback period is estimated at 1.5 years.

Low temperature gasification of poultry litter in a lab-scale fluidized reactor

Low temperature gasification of poultry litter (PL) was experimentally studied in a lab scale fluidized bed reactor. The experiments were carried out at three different equivalence ratios (ER) of 0.17; 0.21; 0.25 and temperature 700 °C, to investigate its impact on cold gas efficiency (CGE), carbon conversion efficiency (CCE), gas yield, lower calorific value (LCV), and tar evolution. Maximum CGE and LCV of the produced gas was 43.4% and 3.34 MJ/m3 respectively at an ER of 0.25. The maximum CCE of 72% was attained at the highest value of ER (0.25). The gas yield showed an increasing trend with ER reaching its highest value of ~1 m3/kgdaf N2 free. Highest amount of total tar was 2.41 g/Nm3 in the dry gas at the lowest tested ER. Styrene- xylene, phenol, and naphthalene, were the components with the highest concentrations of up to 30%, whilst the tar compounds detected but couldn’t be identified ranged between 25-30% with respect to the total tar yield. The average compositions of the main components in permanent gases (vol %, dry basis) at the indicative value of the lowest ER were as follows: H2:7.87%, CH4:2.04%, CO: 6.37%, CO2:11.47%, C2H4:1%, and C2H6:0.22.

Tar yield and composition from poultry litter gasification in a fluidised bed reactor: effects of equivalence ratio, temperature and limestone addition.

Air gasification of poultry litter was experimentally investigated in a laboratory scale bubbling fluidised bed gasifier. Gasification tests were conducted at atmospheric pressure using silica sand as the bed material. This paper examines the effect of the equivalence ratio (ER) in the range of 0.18–0.41, temperature between 700 and 800 °C, and the addition of limestone blended with the poultry litter on the yield and composition of tar. An off-line solid phase adsorption method was employed in order to quantify tar compounds heavier than styrene, whereas lighter species such as benzene and toluene were measured by means of on-line micro gas chromatography. Total tar yields were in the range from 15.7 to 30.7 gtotal tar kgpoultry litter (dry and ash free basis)−1. These values are considered low with respect to the feedstocks with a higher organic fraction. It also needs to be noted that the yields of benzene and toluene were measured by on-line micro gas chromatography, a technique which inherently delivers higher tar values compared to commonly employed off-line techniques. By varying the ER, poultry litter blended with limestone showed a reduction in total tar yield whereas poultry litter on its own showed an increasing tar yield over the ER range tested. In the presence of limestone, polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, toluene and benzene showed a tendency to reduce over the ER range tested. Since the ER also plays a crucial role in tar reduction, the reduction in tar cannot be unambiguously attributed to calcined limestone/lime (CaCO3/CaO). Increasing the temperature was shown to be effective for reducing the total tar yield but the amounts of polycyclic aromatic hydrocarbons increased. However, no definitive correlation could be established between limestone/lime catalytic activity for tar reduction and elevated gasification temperature, because there was no possibility to study their effects separately. The chemical composition of the tar arising from poultry litter is distinctive compared with conventional lignocellulosic fuels linked to the fact that poultry litter has a higher nitrogen content (≈6.5% w/w (dry and ash free basis)). Nitrogen-containing hydrocarbons such as pyridine, 2-methylpyridine, 2-methyl-1H-pyrrole and benzonitrile were identified in significant amounts. This study has demonstrated that poultry litter gasified in a bubbling fluidised bed yielded a product gas with relatively low tar content while its composition reflects the chemical nature of the feedstock.

Poultry Litter Gasification in a Fluidized Bed Reactor: Effects of Gasifying Agent and Limestone Addition

Air and air-steam gasification of poultry litter was experimentally studied in a laboratory scale bubbling fluidized bed gasifier at atmospheric pressure using silica sand as the bed material. The effects of equivalence ratio (ER), gasifier temperature, steam-to-biomass ratio (SBR), and addition of limestone blended with the poultry litter, on product gas species yields and process efficiency, are discussed. The optimum conditions (maximum carbon conversion, gas yield, heating value, and cold gas efficiency) were achieved at an ER 0.25 and 800 °C, using air (SBR = 0) and poultry litter blended with 8% w/w limestone, yielding a product gas with a lower heating value (LHV) of 4.52 MJ/Nm3 and an average product gas composition (dry basis) of H2: 10.78%, CO: 9.38%, CH4: 2.61, and CO2: 13.13. Under these optimum processing conditions, the cold gas efficiency, carbon conversion efficiency, and hydrogen conversion efficiency were 89, 73, and 43% respectively. The reported NH3 measurement at an ER of 0.28 and 750...

Updraft gasification of poultry litter at farm-scale – A case study

Farm and animal wastes are increasingly being investigated for thermochemical conversion, such as gasification, due to the urgent necessity of finding new waste treatment options. We report on an investigation of the use of a farm-scale, auto-thermal gasification system for the production of a heating gas using poultry litter (PL) as a feedstock. The gasification process was robust and reliable. The PL’s ash melting temperature was 639°C, therefore the reactor temperature was kept around this value. As a result of the low reactor temperature the process performance parameters were low, with a cold gas efficiency (CGE) of 0.26 and a carbon conversion efficiency (CCE) of 0.44. The calorific value of the clean product gas was 3.39MJm−3N (LHV). The tar was collected as an emulsion containing 87wt.% water and the extracted organic compounds were identified. The residual char exceeds thresholds for Zn and Cu to obtain European biochar certification; however, has potential to be classified as a pyrogenic carbonaceous material (PCM), which resembles a high nutrient biochar.

Effect of poultry litter biochar diet inclusion on feed manufacture and 4- to 21-d broiler performance

Decreasing diet cost and minimizing environmental impact are current issues that can affect the success of poultry production. In the eastern United States, much concern has been generated surrounding eutrophication of the Chesapeake Bay due to nitrogen and phosphorus leaching from land application of litter. Gasification of poultry litter and feeding the resultant poultry litter biochar (PLB) may be an alternative to traditional land application of litter. In addition, PLB may provide a cost-effective source of essential nutrients for poultry by the partial or complete replacement of rock phosphorus in poultry diets, and may also provide a mechanism for improving feed manufacture variables. The objectives of this study were to assess effects of diet incorporation of PLB on feed manufacture and pellet quality (Study 1) and subsequent feeding effects on broiler performance and tibia ash (Study 2). Seven diets were formulated to compare the replacement of rock phosphorus with PLB. Inclusion of PLB was high, 6.2 or 6.9%, in order to maximize rock phosphorus replacement but also to assess potential detriments. Four diets were chosen to generate replicated feed manufacture and pellet quality data. The addition of PLB to diets was shown to improve pellet quality (P < 0.05). Diets containing PLB decreased live weight gain and FCR; however, a positive yet modest contribution to bone mineralization was demonstrated (P < 0.0001). Therefore, PLB contains available phosphorus and calcium; however, the bioavailability of these minerals relative to rock phosphorus was not equivalent. Furthermore, the particular PLB tested decreased broiler performance.

Inorganic constituents formed during small-scale gasification of poultry litter: A model based study

Europe's vast poultry industry requires a proper waste management in order to comply with environmental regulations. As a result, poultry litter represents a potential fuel candidate for thermal conversion technologies since it is an available source. Therefore, a process simulation for the gasification of poultry litter is examined in this study. This process integrates a fluidised bed gasifier with a gas turbine with the aim of generating combustibles gases for energy production. The system allows the treatment of waste with the additional benefit of energy generation. A small-scale system (200 kWe) installed on-site the biomass source shows to be suitable for a poultry farm to avoid the litter transportation to centralised plants. Among the by-products generated during gasification, such as NOx, SO2, and tar, ash represents a potential risk since bed agglomerates can lead to loss of fluidisation and alkali vapours in the product gases can increase rates of hot corrosion on turbine surfaces. This work presents the partition of the most problematic inorganic species in order to assess the feasibility of the system and identify the optimum parameters to minimise the vaporisation of inorganics. It was found that low ER values produced low HCl emissions and good process efficiencies but released very high SO2 emissions.

Characterisation, kinetics and modelling of gasification of poultry manure and litter: An overview

Environmental implications of the disposal of waste from the poultry industry have created the need for proper waste management. As a result, poultry litter has been proposed as a potential fuel candidate for thermal conversion technologies since it is an available source. This review discusses the recent advances in the physical and chemical characterisation of poultry litter. The focus of this review is on gasification for energy generation and current commercial combustion facilities. Significant advances have been made in the pyrolysis, gasification and combustion investigations with the aim to determine their kinetics. These results are important for modelling work and critical issues for the simulation of poultry litter gasification are discussed.

Gasification of Wood Chips, Agricultural Residues, and Waste in a Commercial Downdraft Gasifier

In this study, gasification of different biomass feedstocks, including pine wood chips, sawdust, peanut hulls, and poultry litter (the latter three in pelletized form), was conducted in a 25 kWe commercially available, mobile downdraft gasifier. Ultimate and proximate analyses were carried out to characterize the biomass feedstocks used for gasification. The synthesis gas obtained from different feedstocks and different operating conditions (biomass flow rate and moisture content) was analyzed using an on-site gas analyzer. Gasification of peanut hull pellets showed the highest heating value (6.1 MJ per normal cubic meter, Nm-3) of synthesis gas, whereas poultry litter gasification gave the lowest heating value (4.8 MJ Nm-3).

Kinetics of Auto-Gasification of Poultry Litter

Thermochemical conversion of poultry litter is the efficient route for its disposal, as well as energy recovery from it. The ultimate analysis of poultry litter indicates that it has sufficient oxygen in itself to convert all the carbon to gaseous products. In order to verify the role of biomass oxygen in the gasification of poultry litter, thermo gravimetric analysis (TGA) of poultry litter was carried out with a nitrogen and air environment with particle size ranging from 100 microns to 3 mm and at a heating rate of 5 to 50°C/min. Heating of poultry litter at a rate less than 15°C/min in static air or nitrogen environment has resulted in complete gasification yielding ash at less than 600°C. This establishes the auto gasification of poultry litter by the oxygen present in the litter itself. Poultry litter is highly porous and a continuous reaction model seems to apply. Using the TGA data, the kinetics of auto gasification of poultry litter was elucidated at a heating rate of 5°C/min with static air and nitrogen separately. There are four zones. The first zone represents moisture removal between 30°C and 120°C, the second zone of thermal degradation between 200°C and 310°C, the third zone between 310°C and 440°C and the forth zone between 440°C and 600°C. The first order rate equation was used to evaluate the rate constant. The effect of temperature on rate constant was explained using the Arrhenius equation. The values of Arrhenius frequency factors (A) and activation energies (E) for static air and nitrogen environments coincide with each other in magnitude, proving the feasibility of auto gasification once again. The calculated weight loss using kinetic parameters was found to match the experimental weight loss satisfactorily.

Investigation of Nitrogen-Bearing Species in Catalytic Steam Gasification of Poultry Litter

The production of broiler chickens has become one of the largest sectors in U.S. agriculture, and the growing demand for poultry has led to an annual production growth rate of 5%. With increased demand for poultry, litter management has become a major challenge in the agriculture industry. Although the catalytic steam gasification has been accepted as a possible and feasible method for litter management, concern has been expressed about the presence of nitrogen and phosphorus containing species in the fuel gas and/or in the final solid residue. The possible release of phosphorus as phosphine gas in the fuel gas can have an adverse impact on the environment. Similarly, possible release of ammonia from the nitrogen containing species is also not acceptable. Hence, under partial U.S. Department of Agriculture support, a study was conducted to examine the fate and the environmental impact of the nitrogen- and phosphorus-containing species released during catalytic steam gasification of poultry litter. From various preliminary tests, it was concluded that most (∼100%) of the phosphorus would remain in the residue, and some (20–70%) of the nitrogen would end up as ammonia in the fuel gas. The effects of temperature, catalyst loading, and type of catalyst on ammonia liberation were studied in a muffled furnace setup at atmospheric pressure. The fraction of nitrogen released as ammonia was found to decrease with an increase in temperature during pyrolysis and steam gasification. It also decreased with an increase in catalyst loading.

Preliminary Economic Analysis of Poultry Litter Gasification Option with a Simple Transportation Model

Several environmental issues are related to the disposal of poultry litter. In an effort to provide a more environmentally friendly alternative than landfill disposal or spreading as a soil amendment, work has been carried out previously at the University of Tennessee Space Institute (UTSI). This past UTSI work was concentrated on developing a catalytic steam gasification concept to produce energy from poultry litter. In the past UTSI studies, preliminary design and economics for a stationary, centralized gasification plant capable of processing ∼100 ton/day of poultry litter were developed. However, in this preliminary design the economic impact of transporting litter to a centralized gasification plant location was not addressed. To determine the preliminary impact of transporting the poultry litter on the overall economics of this energy conversion plant design, a simple transportation model was developed. This model was used in conjunction with the earlier plant design prepared at UTSI to determine the economic feasibility of a centralized, stationary poultry litter gasification plant. To do so, major variables such as traveling distance, plant feed rate (or capacity), fluctuations in the sales price of the product gas (that means value of the energy), population density of poultry farms, impact of tipping fees, and cost of litter were varied. The study showed that for plant with a capacity of 1000 ton/day to be able to withstand several changes in economic conditions and sustain itself, the poultry farm density would need to be ∼0.3 houses/mi2. Smaller plants would need either a higher energy price or some kind of subsidy to be economically feasible.