Coal gasification demonstrated

October 23, 2012 by Linda Morton
Coal gasification demonstrated
Molten catalytic reactor design. Steam and coal react in a bed of molten alkali salts. Isometric and cutaway views. (Furnace not shown.)

DOE's National Energy Technology Laboratory (NETL) has developed a molten catalytic process for converting coal into a synthesis gas consisting of roughly 20% methane and 80% hydrogen using alkali hydroxides as both gasification catalysts and in situ CO2 and hydrogen sulfide (H2S) capture agents.  This hydrogen- and methane-rich output from the gasifier could be sent to gas turbines or solid oxide fuel cells in order to generate electricity with CO2 emissions significantly less than 1.0 lbs of CO2 per kWh of electricity. 

A patent application on this topic has been submitted and a paper entitled "Molten Catalytic Coal Gasification With In Situ Carbon and Sulphur Capture" was published by the Royal Society of Chemistry's journal Energy & Environment Science. 

Baseline studies were conducted using no catalyst, weak capture agents (calcium silicate), and a strong in situ capture agent for acid gases (calcium oxide-CaO). Parametric studies were conducted to understand the effects of temperature, pressure, catalyst composition, steam flow rate and the ratio of coal to hydroxide on the performance of the molten catalytic gasifier in terms of kinetics and syngas composition. 

To measure the amount and the rate of coal conversion, the researchers developed a method for quantifying the coal conversion related to the chemical oxygen demand remaining in the coal. This method was necessary because the capture reactions and the water condenser before the mass spectrometer make a real-time elemental balance impossible. 

For many different reforming, gasification, and combustion experiments, measuring the change in the chemical oxygen demand of coal/fuel can be a more useful definition of coal/fuel utilization than measuring the change in the weight of the coal/fuel or measuring the change in carbon content of the coal/fuel.

Explore further: Coal gasification -- myths, challenges and opportunities

More information: pubs.rsc.org/en/content/articl … e21989a#!divAbstract

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6 comments

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Husky
not rated yet Oct 23, 2012
How does it comapre in terms of efficiency and environmental impact with coalplants that have post burning carbon scrubbers?
Howhot
not rated yet Oct 24, 2012
You have to wonder where all of the other nasty materials go, like the mercury, chromium, and sulfur that's typically found in coal?
Job001
1 / 5 (1) Oct 24, 2012
You have to wonder where all of the other nasty materials go, like the mercury, chromium, and sulfur that's typically found in coal?

In Situ means most nasty materials including the excess carbon remain in the coal bed. A cost comparison to cheap natural gas would be helpful. Not having to mine and ship coal is an advantage but cheap natural gas may make this a useful future potential process.
nappy
1 / 5 (1) Oct 24, 2012
Going back to 19th century technology may not be real smart. There aer thousands of manufactured gas plants lying about that need cleaned up.
deatopmg
1 / 5 (1) Oct 25, 2012
Interesting, as far as it goes, BUT where do the alkali hydroxides come from? They have to be generated electrolytically from the chhlorides, producing chlorine.

Where does all that chlorine get used? Primarily, in the production of chlorinated plastics. The balance between alkali hydroxide production/usage and chlorine usage is somewhat in balance today.

What happens if something like this scheme is used widely to produce H2/CH4 for electricity production? Where does all that excess chlorine go (as opposed to the CO2 if the coal was burned to generate electricity conventionally)? Which is worse for the environment all natural and essential CO2 or chlorine?

There is no free lunch!

Just another example of your government wasting your money.
holoman
not rated yet Oct 25, 2012
Should be able to process several ounces a month.

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