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 industry’s 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
Gasification Technology and R&D. (n.d.). U.S. Department of energy. Retrieved November 20, 2007, from
l Higman, C., & Van Der Burgt, M. (n.d.). Gasification. Elsevier. Retrieved November 20, 2007, from     Google Book Search database:
Underground Coal Gasification. (n.d.). World Coal Institute. Retrieved November 20, 2007, from World     Coal Institute Web site: