Coal%20Gasification%20Technology%20and%20Syngas%20Production

1
Coal Gasification Technology and Syngas Production

• Ruben Reyes
• ChE379

2
Purpose/Outline

• Gasification technology
• Different types of gasifiers
• Products from gasification
• Syngas production, Gasifiers used for IGCC power
  plants
• Conclusion

3
Coal Gasification Technologies

• Basic Overview of gasification
• Coal or other fuels
• Oxidation carefully controlled
• H2, CO2, CH4, other products
• H2 can be purified
• Ash/slag leftovers
• 3 types of gasifiers
• Moving bed
• Fluid Bed
• Entrained Flow
• Underground Coal Gasification
• Vertical wells and pathway creation
• Controlled retraction injection point

4
Above ground gasification
BGL gasifier (fixed bed, slagging)

• Moving bed reactor (Lurgi dry ash and BGL -
  slagging)
• Counter-current flow of coal and oxidizing blast
• Blast composed of air and hot syngas, so low
  oxygen consumption
• Operates on reactive carbon sources
• Good heat transfer heats the carbon source
  creating methane and tar
• Post production cleaning and scrubbing requires
  greater energy use

Figure 1 BGL Gasifier
5
Above Ground Gasification
Winkler Gasifier (Fluid bed, dry ash)

• Fluid-bed reactor (Winkler, HTW, CFB dry ash
  KRW, U-Gas Agglomerating)
• Air fluidizes a bed and carbon containing
  particles added
• Proper mixing of fuel and oxidant provide good
  mass transfer and heat transfer
• Fine particle will escape with syngas and needs
  to be cleaned
• Very good heat/mass transfer so partially reacted
  carbon may settle with ash
• Slagging will reduce fluidization, so temp
  remains below softening point for ash

Figure 2 Winkler Gasifier
6
Above Ground Gasification
Texaco Gasifier (entrained flow, slagging)

• Entrained flow reactors (Shell, Texaco, E-gas,
  Noell, KT - Slagging)
• Carbon source is made of very fine particles in a
  liquid or slurry for very good mass transfer
• Very little residence time
• Co-current flow with oxygen where high
  temperatures can be reached
• Low heat transfer means hot exiting gas with no
  methane or tar, but more oxygen required.
• High temperature and very small carbon sources
  make it an ideal process for coal gasification.
• High temperatures without charring
• No agglomeration because of fine particle size
  preparation

Figure 1 Texaco Gasifier
7
Underground Coal Gasification

• Vertical wells, soviet technology
• H2 and O2 are injected and ignited to create
  syngas, CO2 and methane
• Coal deposits do not allow for transport of the
  gases from the injection well to recovery well
  very easily
• Closely spaced wells and reverse combustion
  methods are employed to create a cavity between
  wells
• This process works, but requires many wells to be
  constructed

Figure 5 Current UGC
8
Underground Coal Gasification

• Controlled retraction injection point from oil
  technology (CRIP)
• The oil industrys horizontal drilling for
  production and injection wells to deliver and
  absorb syngas continuously
• Only one injection well, the ignition continues
  through the inseam as the injection wells are
  retreated.
• The product is collected in a product well
• Concerns about ground water inhibit the use of
  UCG.

Figure 6 CRIP UGC
9
Syngas production and energy industry

• CO2 removal
• Used for oil reclamation
• Can be injected back in ground
• Combined cycle
• Combustion turbine
• Heat used for generating steam
• Fuel cell uses

10
Conclusions

• There are many ways that carbon containing
  compounds may be gasified
• Coal gasification occurs best in entrained flow
  reactors such as the Texaco gasifier
• The coal will not heat up as much and will not
  create methane and tar.
• The requirement for fine particles into the
  gasifier prevents agglomeration
• Underground coal gasification technology is
  present and used today but with certain
  challenges
• Water contamination
• Impact on environment and land
• Potential benefits are many
• Syngas used in combined cycle energy production
• Hydrogen fuel cell use for energy production and
  transportation purposes
• Methane and hydrogen have applications in the
  chemical industry where they can be used.
• Not mentioned, gasification is first step in coal
  liquefaction process.
• Coal gasification could reduce dependence on
  foreign oil
• CO2 sequestration

11
References

• Gasification reference shelf - images and photos.
  (n.d.). National Energy Technology
  Laboratory.     Retrieved November 20, 2007, from
  http//www.netl.doe.gov/technologies/coalpower/gas
  ification/pubs/photo.html
• Gasification Technology and RD. (n.d.). U.S.
  Department of energy. Retrieved November 20,
  2007, from http//www.fossil.energy.gov/programs/p
  owersystems/gasification/index.htm
• l Higman, C., Van Der Burgt, M. (n.d.).
  Gasification. Elsevier. Retrieved November 20,
  2007, from     Google Book Search database
  http//books.google.com.ezproxy.lib.utexas.edu/   
    books?idZUlRaUrX8IUCprintsecfrontcoverdqgas
  ificationsigSxb9s5qmKK03xe9INbsiuoJwwX8PPP1,M1
  
• Underground Coal Gasification. (n.d.). World Coal
  Institute. Retrieved November 20, 2007, from
  World     Coal Institute Web site
  http//www.worldcoal.org/pages/content/index