Coal pyrolysis and hydropyrolysis

Howard, J. B., Fundamentals of Coal Pyrolysis and Hydropyrolysis, in Chemistry of Coal Utilization, M. A. Elliott (Ed.), Second Supplementary Volume, pp. 665-784, John Wiley Sons, New York, 1981. 

Suuberg, E.M. Rapid pyrolysis and hydropyrolysis of coal. ScD Thesis, MIT, 1977. 

Suuberg, F. M. "Rapid Pyrolysis and Hydropyrolysis of Coal", Ph.D. Dissertation, Massachusetts institute of Technology, Cambridge, Mass., 1977. 

Hydropyrolysis occupies a position midway between coal pyrolysis and coal liquefaction. This process, which is currently being developed to complement coal liquefaction, operates at pressures up to 100 bar and temperatures up to 900 °C the residence time of the coal in the pyrolysis zone is around 4 to 5 sec. 

The effect of hydrogen on coal pyrolysis can further be illustrated by Figure 4, where we compared derivative thermograms of Wyoming coal pyrolyzed at 200 psig of N2 and 200 psig of H2 at the same heating rates (20 C/min). The secondary hydropyrolysis peak... 

Chapters 10-12 cover important aspects of coke formation in metal tubular reactors during pyrolysis of hydrocarbons. Chapters 13 and 14 are concerned with coal and lignite pyrolysis. Chapters 15 and 16 deal with pitch formation from, respectively, heavy petroleum fraction and tar sand bitumen. Chapters 17 and 18 cover studies on the mechanisms of thermal alkylation and hydropyrolysis. Chapters 19 and 20 on oil shale deal with the properties of oil shale and shale oil as developed by techniques of microwave heating and thermal analysis. 

TIjffective use of the vast coal reserves of the United States requires quantitative information on their conversion behavior in commercially important reactions. Studies using small-scale equipment and aimed at determining the effects of temperature, pressure, particle size, and heating rate on the rapid thermal decomposition of coal in atmospheres of both helium (pyrolysis) and hydrogen (hydropyrolysis) have been in... 

Thus, while flash pyrolysis and flash hydropyrolysis have not advanced too far beyond the bench-scale studies, there are several potential commercial ventures that employ the pyrolysis of coal as a means of producing liquid products that are becoming more and more viable with the ever-increasing price of petroleum and the more conventional liquid fuels (Chapters 18,19, and 26). 

TABLE 17.5 Representative Operating Conditions and Yields for Contemporary Coal Pyrolysis, Hydropyrolysis, and Extraction Processes... 

Process development of the use of hydrogen as a radical quenching agent for the primary pyrolysis was conducted (37). This process was carried out in a fluidized-bed reactor at pressures from 3.7 to 6.9 MPa (540—1000 psi), and a temperature of 566°C. The pyrolysis reactor was designed to minimize vapor residence time in order to prevent cracking of coal volatiles, thus maximizing yield of tars. Average residence times for gas and soHds were quoted as 25 seconds and 5—10 rninutes. A typical yield stmcture for hydropyrolysis of a subbiturninous coal at 6.9 MPa (1000 psi) total pressure was char 38.4, oil... 

Hydropyrolysis A catalytic process for converting coal into a mixture of liquid and gaseous products. It is operated at high temperatures and pressures, with a residence time in the pyrolysis zone of only a few seconds. 

Coal hydropyrolysis is defined as pyrolysis under hydrogen pressure and involves the thermal decomposition of coal macerals followed by evolution and cracking of volatiles in the hydrogen. It is generally agreed that the presence of hydrogen during the pyrolysis increases overall coal conversion. (, )... 

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