Reactor hydropyrolysis

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... 

In this paper we have looked firstly at the effect that the catalyst concentration, secondly at the effect that the reactor temperature and finally at the effect that the residence time at temperature have on the chemical structure of the oils (hexane soluble product) produced on hydropyrolysis (dry hydrogenation) of a high volatile bituminous coal. Generally, the hydropyrolysis conditions used in this study resulted in oil yields that were considerably higher than the asphaltene yields and this study has been limited to the effects that the three reaction conditions have on the chemical nature of the oils produced. 

W. -C. Xu, K. Matsuoka, H. Akiho, M. Kumagai and A. Tomita, High pressure hydropyrolysis of coals using a continuous free-fall reactor. Fuel, 82, 677-685 (2003). 

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. 

Figure 14. Flow diagram of bench-scale hydropyrolysis unit 1. drier, 2. pressure regulator, 3. air inlet, 4. rotameter, 5. c/iecfc valve, 6, 9. thermocouples, 7. preheater, 8. reactor, 10. condenser, II, 12, collectors, 13, 14. /too control valves, 15. CdCl2 scrubber, 16. tesf meter, 17. piston pump, 18, 19. rupture discs, 20. reciporating pump, 21. oil reservoir, heated.

Hydropyrolysis Process. Two hydropyrolysis reactors were used in this study. The Sunnyside and Asphalt Ridge bitumen were processed in a reactor consisting of a coiled stainless steel tube 3/16" i.d. x 236" long. This reactor has been previously described by Ramakrishnan (1). The TS-IIC oil was processed in a reactor originally developed for short residence time coal liquefaction. This reactor also consists of coiled stainless steel tubes 3/16" i.d. The length of this tube system can be varied from 20 to 120 feet, and has been previously described by Wood, et al. (10). The length of the reactor for runs reported in this paper was 100 feet. Average residence times were calculated from the volumetric flow rates and the reactor volume at process conditions. The reaction mixture, which is predominantly H, was assumed for purposes of this calculation to behave as an ideal gas. The reactors were pre-sulfided with H S to inhibit catalytic reactions from wall surfaces. 

The reactions taking place during hydropyrolysis are probably dominated by free radical chemistry. Catalytic effects from reactor components or trace minerals found in the feedstocks cannot, however, be discounted. Cracking reactions are probably initiated through thermally induced unimolecular bond scission. 

The pyrolysis and hydropyrolysis process produces liquid product and char Either fluidized beds or entrained beds are used for this process The reaction kinetics and reactor modelling of solid-gas systems have already been discussed earlier ... 

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