Low temperature gasification of poultry litter in a lab-scale - - PowerPoint PPT Presentation

2nd International Conference on Sustainable Energy and Resource Use in Food Chains

RCUK Centre for Sustainable Energy Use in Food Chains

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

Giannis Katsaros, Daya Shankar Pandey, Alen Horvat, Savvas Tassou

Brunel University London Paphos, Cyprus, 17.10.2018

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Background

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Key drivers for the growth of poultry production Shorter production cycles, cheaper prices and better nutritional image.

• Meat production increases continuously

throughout the years reaching annual global production of 315 million tons in 2015.

• Among the different meat segments poultry

is expected to have the highest development.

• In UK, 32% increase of slaughtered poultry

between 1995-2015.

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Background

• In 2014, 1.4 billion tons of manure were generated in EU member states.
• Intensive livestock farming, causes large accumulation of waste

in concentrated areas.

• Manure land applications as an organic fertiliser is the first management
• ption if possible.
• Over application of manure leads to excessive fertilization of agricultural land.

Associated problems are eutrophication, nitrate leaching, crop toxicity, odours and emissions of greenhouse gases.

What are the alternatives??

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On-farm combustion Anaerobic digester Solid/Liquid separation Phosphorus removal pond Liquids for irrigation Drying Gasification IGCC systems Raw manure, urine, bedding etc.

Path 1: Biological treatment Path 2: Gasification Path 3: Re-burning Path 4: Co-firing Path 5: Combustion

Grinding Re-burning coal with biomass Co-firing coal and biomass Ash Fertilizer Heat & power generation

Solids Liquids Solids Effluent Liquids

Heat & power generation

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Gasification technology

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Gasification is a thermochemical process during which a carbon based feedstock is dissociated in a high temperature environment and is converted into a combustible gas by the supply of a gasification agent in a reduced environment. Pyrolysis ER=0 Gasification ER=0.1-0.4 Combustion ER>1

𝐹𝑆 =

ൗ

𝐵𝑗𝑠 𝑔𝑚𝑝𝑥 𝑠𝑏𝑢𝑓 𝐶𝑗𝑝𝑛𝑏𝑡𝑡 𝑔𝑚𝑝𝑥 𝑠𝑏𝑢𝑓 𝑏𝑑𝑢𝑣𝑏𝑚

ൗ

𝐵𝑗𝑠 𝑔𝑚𝑝𝑥 𝑠𝑏𝑢𝑓 𝐶𝑗𝑝𝑛𝑏𝑡𝑡 𝑔𝑚𝑝𝑥 𝑠𝑏𝑢𝑓 𝑡𝑢𝑝𝑗𝑑ℎ𝑗o𝑛𝑓𝑢𝑠𝑗𝑑

Increase of oxygen content

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Different applications of gasification

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Challenges of gasification (TAR)

• Syngas contains different kind of impurities, such as tar, particles, sulphur

compounds and alkali metals.

• Tar is a mixture of complex hydrocarbons which cause fouling and clogging
• f the equipment located downstream when temperature falls below

tar dew point.

• Different tar concentration limits apply depending on the final application, e.g.

in internal combustion engines the maximum limits are 50-100 mgtotal tar/Nm3.

• Presence of tar and the subsequent cleaning required increase the complexity

and the total costs of the plant.

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Challenges of gasification (Agglomeration)

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• Agglomeration is caused by melting of the inorganic components
• f the fuel.
• Bed agglomeration can result in de-fluidization and consequently

complete shut down of the gasifier.

• Most well known inorganic compound that can cause agglomeration is

Potassium (K). When silica sand is applied as bedding material, it can potentially form a low melting potassium silicate.

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Challenges of gasification (Agglomeration)

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Characterisation of poultry litter

Ultimate Analysis

Component

• wt. (%) – dry basis

Carbon 42.72 Hydrogen 5.51 Nitrogen 3.93 Sulphur 0.64 Chlorine 0.29 Oxygen 32.59 LHV (MJ/kg, dry) 16.78 10

Proximate Analysis (%)

14.3 20.7 69.6 9.71

Ash FC VM Moisture

Oxides

Al Ca Fe Mg Na P K Si

mg/kg 1200

15500 1600 8200 4200 10200 27700 7300

Ash composition (dry basis)

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Experimental facility

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where, (1) biomass hopper (2) feeding screws (3) air preheater (4) gasifier reactor (5) cyclone (6) valve (7) hot filter (8) cold filter (9) flare

• Feedstock: Poultry litter
• Silica sand used as a bed material
• Feeding rate 0.5 kg/h (as received basis)
• Air and nitrogen as fluidisation mediums
• Gasification set-point temperature 700°C
• Minimum fluidisation velocity 0.036 m/s
• Equivalence ratio 0.17/0.21/0.25

Operating conditions

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Effect of ER on gas composition, gas yield, and LCV

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• CO2, H2 and CO increase with ER

while CH4 and C2H4 show a stable trend

• Both gas yield and LCV increase with ER

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Effect of ER on carbon conversion efficiency and cold gas efficiency

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𝐷𝐷𝐹 = 𝐷𝑒𝑠𝑧_𝑕𝑏𝑡 𝐷𝑒𝑠𝑧_𝑗𝑜𝑞𝑣𝑢 𝐷𝐻𝐹 = 𝑀𝐷𝑊 ∗ ሶ 𝑛𝑒𝑠𝑧_𝑕𝑏𝑡 𝑀𝐷𝑊 ∗ ሶ 𝑛𝑒𝑠𝑧_𝑔𝑣𝑓𝑚

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Effect of ER on tar evolution

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(a) (b)

• Decline of total tar concentration

as ER increases

• Styrene xylene, phenol and naphthalene

the most abundant tar compounds

• Tar dew point 100 °C at ER 0.17

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Mass balance of gasification test (ER 0.25)

15 Carbon Product gas : 72% Cyclone fines: 2.4% Bed : 8% Gasifier Product gas : 84% Cyclone fines: 0.4% Gasifier Bed : 0.05% Hydrogen Sulphur Bed : 23% Gasifier Cyclone fines: 48% Product gas: 17% Nitrogen Gasifier Product gas: 102%

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Conclusions

• No sign of agglomeration was detected at 700 °C and all the experiments were

conducted successfully.

• Gasification of poultry litter resulted in the production of low calorific value

syngas.

• Carbon Conversion Efficiency increased with ER acquiring the highest value
• f 72% at ER 0.25 and T 700 °C.
• Amount of total detectable tar was low, showing a decreasing trend with ER.

However the impact of tar on the performance of downstream processes is mostly related to tar composition and concentration.

• Higher temperatures of gasification and the use of additives should be tested

in order to investigate the operational feasibility and their impact on process performance parameters.

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Acknowledgements

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