My radiant padlet by https://padlet.com/20006270_2/anmyjrxqgxlaa0sj Made with big dreams en-us 2021-12-06 04:20:07 UTC 2026-01-27 19:49:44 UTC hello@padlet.com What is gasification and how does it produce syngas from biomass? (D) 20015272_4 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930345576 Gasification is a process that converts biomass- or fossil fuel  into gases (Carbon monoxide, carbon dioxide, hydrogen, methane, carbon dioxide)

in the gasifier - a high temperature/pressure vessel where oxygen and steam directly contact with coal or other feed material causing a series of chemical reactions to occur that convert feed into syngas and ash/slag.
Gas stream cleanup/component separation (Products)
  • syngas further converted to hydrogen and carbon dioxide by adding steam and reacting over a catalyst in a water-gas shift reactor. when hydrogen is burned, it only created heat and water, resulting in the ability to create electricity with no carbon dioxide in the exhaust gases
  • Hydrogen made from coal or other solid fuels can be used to refine oil, or make products such as ammonia and fertiliser. 
  • hydrogen enriched syngas can be used to make gasoline and diesel fuel (transportation fuels)
  • carbon dioxide can be captured from the syngas, preventing the emission of GHGs to atmosphere and enabling utilization (enhanced oil recovery) or safe storage
]]> 2021-12-06 04:20:58 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930345576 Since gasifications helps to converting organic waste (biomass) to energy, what are some of the diffferent methods and what pros and cons do they have depending on the context of their uses. How should we evaluate the different methods? 20015272_4 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930350472 2021-12-06 04:25:35 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930350472 Exothermic and Endothermic Processes of Gasification (C) 200071622 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930351767 Exothermic: Process that gives off heat
Endothermic: Process that takes in heat

drying - endothermic
pyrolysis - endothermic
combustion - exothermic
cracking - endothermic
reduction - endothermic

  • CO + H2O ↔ CO2 + H2 (water gas shift reaction)
  • C + CO2 ↔ 2CO (reverse boudouard reaction)
  • C + 2H2 ↔ CH4  (methanation reaction)
  • CH4 + H2O ↔ CO + 3H2 (steam methane reforming reaction)
]]> 2021-12-06 04:26:44 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930351767 What are the type of gasifiers? (K) 20006270_2 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930352035
  • Fixed-bed up-draft
  • Fixed-bed down-draft
  • fixed-bed cross-draft
  • circulation fluidised bed 
    • ]]>     2021-12-06 04:27:00 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930352035     What are their similarities and difference (K) 20006270_2 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930353343 Similarities :
    • all the feed, which is the biomass, is being introduced into the gasifier through the top.
    • all of the gasifiers produce ash/char (all of them have an ash pit to collect ash or char)
    • They all require the introduction of air for combustion to take place.
    • They all have a cylindrical shape which promotes the flow of gases.
    Difference :
    • The flow of air entering 
      • The airflow upwards, downwards and the side of the reactor. 
    • The flow of the producer air 
      • Producer gas is extracted from the top for updraft gasifier
      • Producer gas is extracted from the bottom for downdraft gasifier
      • Producer gas is extracted from opposite the air nozzle at the grate
    ]]>     2021-12-06 04:28:23 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930353343     Energy storage in gasification process (C) 200071622 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930355688 Energy stored in CH4, CO, and H2, which are all unstable, means that energy can be stored in these compounds and elements.  CO2 does not store any energy as it is a stable compound, and does not go through combustion.

    During the process of Gasification, the exothermic reactions give off heat, which is taken in by endothermic reactions where the energy stored can be burned off to give out energy.


    ]]>     2021-12-06 04:30:34 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930355688     Gasification vs direct combustion (D) 20006270_2 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930358485 gasification 
    advantages:
    • cost of energy generated through biomass is reduced through the gasification route
    • it provides a significant life cycle cost advantage over hydrocarbon and ultimately leads to the development of a sustainable energy system
    • gasification is much cheaper than other energy production methods such as solar energy (gasification is 15-20 times cheaper)
    • cleaner than direct combustion
    • better efficiency at small scale
    • little GHG emissions compared to direct combustion
    disadvantages:
    • rural areas have a lack of access to electricity. causing them to rely on primitive forms of energy like dung and fuel wood.
    • it has lesser efficiency due to low heating value from lack of internal heat exchange

    direct combustion:
    advantages:
    • Low running cost
    • the biomass treatment is simple
    • it has a closed carbon cycle, contributing less to global warming and are sustainable in nature
    disadvantages:
    • Low efficiency 
    • Large specific size
    • production of carbon monoxide from this combustion if in excess can be fatal to people
    ]]>     2021-12-06 04:33:18 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930358485     What are some of their disadvantages and advantages? 200293042 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930361403 ++ of fixed bed up draft:
    - Simple
    - High charcoal burn-out and internal heat exchange, which can lead to low
    gas exit temperatures   
    - High equipment efficiency
    - Possibility of operating with many types of feed stock

    Disadvantages:
    - Channelling in the equipment  can lead to oxygen break-through
    - Dangerous and explosive situation
    - Necessity to install automatic moving grates
    - Problems associated with disposal of tar-containing condensates

    ++ of fixed-bed down draft:
    - It is possible to produce tar-free gas suitable for engine application.
    - Suffer less from environmental objections due to lower level of organic components

    Disadvantages:
    - Unable to operate on many unprocessed fuels
    - Suffer from high ash content fuels (slagging)
    - Lower efficiency resulting from the lack of internal heat exchange as well as the lower heating value of the gas.

    ++ of fixed-bed cross draft: (C)
    - Economically feasible due to low shaft power of 10kW
    - Very simple gas-cleaning train can be employed when using this type of gasifier in conjunction with small engines.

    Disadvantages:
    - Minimal tar-converting capabilities 
    - Consequent need for high quality charcoal (Low volatile content)

    ++ of circulation fluidised bed: (C)
    - Easy control of temperature which can be kept below the melting/fusion point of the ash
    - Able to deal with fluffy and fine grained materials w/o the need of pre-processing 


    Disadvantages:
    - Erosion can occur on the tubes inside the boiler.
    - The uneven temperature distribution could be caused by clogging of the air inlet of the bed.  
    - Long starting time up to 48 hours.
    - High tar content of the product gas
    ]]>     2021-12-06 04:36:02 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930361403     Syngas (T) 200071622 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930374316 Consists of: Hydrogen, carbon monoxide, and carbon dioxide

    Biomass | A | B | C
    H2 | 7 – 9% | 15 – 17% | 14.9%
    CO | 9 – 13% | 21 – 22% | 46.5%
    CO2 | 12 – 14% | 10 – 11% | 14.6%
    H2O | 10 – 14% | Dry | Dry
    CH4 | 6 – 9% | 5 – 6% | 17.8%
    C2+ | 0% | 0% | 6.2%
    N2 | 47 – 52% | 46 – 47% | 0
    Heating value (MJ/m3) | 4.5 – 5.5 | 7.5 | 18

    C is the better syngas: Why? How are these components important to syngas composition?

    - Most carbon monoxide as compared to the rest which goes through combustion to form carbon dioxide
    - It has higher methane which contributes to its high heating value
    - 0 nitrogen (%),it uses pure oxygen thus nitrogen does not take up space in the composition of syngas.
    - It has relatively high hydrogen which can also go through combustion to form water.]]>     2021-12-06 04:47:51 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930374316     Since syngas is a product of gasification, what is syngas? 200293042 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930395168 2021-12-06 05:06:19 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930395168 Syngas compared to other gases (T) 200293042 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930404129 Syngas comparison vs natural gas vs biogas:
    Syngas: Syngas has 50% of the energy density of Natural gas
    Biogas: 20 - 26 MJ/m^3
    Natural gas: Around 38.3 MJ/m^3
    Conclusion:
    Both biogas and natural gas have higher energy density as compared to syngas which means they are more energy-dense and more useful. 


    ]]>     2021-12-06 05:14:34 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930404129     How is energy stored in the gasification process 200293042 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930422675 2021-12-06 05:32:57 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930422675 200293042 https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930434014 Start - Yellow  End- green]]> 2021-12-06 05:44:53 UTC https://padlet.com/20006270_2/anmyjrxqgxlaa0sj/wish/1930434014