Lignite pyrolysis

Pyrolysis. All of the Texas lignite pyrolysis data reported in the literature have been based on slow pyrolysis rates (e.g., 3-10 C/min). Goodman et al. (20) performed an early study (1958> on the effect of final carbonization temperature on the yields from several lignites, one of which was a Wilcox lignite. More recently Edgar et al. (21) reported a series of atmospheric pressure studies to evaluate the effects of other carbonization parameters (heating rate, particle size) on carbonization yield and decomposition rate. 

MORGAN AND JENKINS Exchangeable Cations in Lignite Pyrolysis... 

Cationic Effects During Lignite Pyrolysis and Combustion... 

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. 

Most of these phases are much more distinct for the lignite, which exhibits almost a step-like behavior believed to reflect formation of individual volatiles by one, two, or possibly three specific primary decomposition reactions or reaction pathways. In fact, the volatiles product spectrum for the lignite pyrolysis is dominated by just three compounds (C02, CO, and H20), allowing the essential features of the decomposition to be described quite well by a small number of product formation steps. Also, these compounds are relatively stable to further (secondary) reaction at the residence times and temperatures prevailing in this work. Thus these three products are far from water gas shift equilibrium (except at temperatures above 1000°C), and from equilibrium with solid carbon unless a total pressure of 1000 atm is postulated to occur inside the decomposing lignite particles (8). 

A semiempirical model of lignite pyrolysis has been developed in which the rate of formation of each of the key components (e.g., H20,... 

The research effort pursued several objectives (1) studies of the lignite pyrolysis, (2) research on catalyst improvement for cracking and upgrading of the volatile tars (sulfur, oxygen and nitrogen removal), (3) catalyst regeneration studies including how to handle the substantial heat developed. 

---