Liquefaction partial conversion

N. Berkowitz (Alberta Research Council) provided a stimulating account of the potential of coal in Canada s energy future. Coal can be used directly as an industrial fuel or be converted to other combustible hydrocarbons. Berkowitz described the three different conversion techniques gasification, liquefaction, and partial conversion techniques to produce gases, oils, and solid fuels. 

The chemistry of a third group of conversion techniques -i.e., partial conversion methods which skim hydrocarbon gases and/or liquids from the coal and leave a char suitable for use as a boiler fuel or gasification feedstock - is. If anything, even more speculative than the chemistry of liquefaction. 

This paper touches on the chemistry of coal gasification and liquefaction comments on the current status of conversion processes and the influence of coal properties on coal performance in such processes and examines the contributions which coal conversion could make towards attainment of Canadian energy self-sufficiency. Particular attention is directed to a possible role for the medium-btu gas in long-term supply of fuel gas to residential and industrial consumers to linkages between partial conversion and thermal generation of electric energy and to coproduction of certain petrochemicals, fuel gas and liquid hydrocarbons by carbon monoxide hydrogenation. 

It is well known that during liquefaction there is always some amount of material which appears as insoluble, residual solids (65,71). These materials are composed of mixtures of coal-related minerals, unreacted (or partially reacted) macerals and a diverse range of solids that are formed during processing. Practical experience obtained in liquefaction pilot plant operations has frequently shown that these materials are not completely eluted out of reaction vessels. Thus, there is a net accumulation of solids within vessels and fluid transfer lines in the form of agglomerated masses and wall deposits. These materials are often referred to as reactor solids. It is important to understand the phenomena involved in reactor solids retention for several reasons. Firstly, they can be detrimental to the successful operation of a plant because extensive accumulation can lead to reduced conversion, enhanced abrasion rates, poor heat transfer and, in severe cases, reactor plugging. Secondly, some retention of minerals, especially pyrrhotites, may be desirable because of their potential catalytic activity. 

The claims of exclusive formation of rac-stilbene dichloride upon gas-solid addition of chlorine to frans-stilbene (103) [71] and of meso-stilbene dibromide in the gas-solid addition of bromine to trans- or czs-stilbene [54] could not be verified. Scheme 12 shows the results of more detailed studies indicating the mesolrac ratios on the solid-state chlorination and bromination of trflns-stilbene (103) and some variations when the crystal size was changed [58, 60-61]. There is a risk of partial transient liquefaction if the chlorine is added too rapidly, due to initially heavy reaction. But even at the start with a stoichiometric amount of chlorine at 0.1 bar and 0 °C, a persistent product layer forms on the unground crystal powder of 103 that cannot be disintegrated by the ultrasound of a cleaning bath at 20 °C for 60 h (only 7% conversion with mesolrac ratio of 11 89 under these conditions) [22]. It is therefore unavoidable to mill the crystals of 103 to sizes <1 pm in order to overcome these rare diffi-... 

Balachandran, U., Si. Morissette, J.T. Dusek, Ri. Mieville, R.B. Poeppel, M.S. Kleefisch, S. Pei, TP. Kobylinski and C.A. Udovich, 1993, Development of ceramic membranes for partial oxygenation of hydrocarbon fuels to high-value-added products, in Proc. Coal Liquefaction and Gas Conversion Contractors Review Conf., Pittsburgh, 1993 (U.S. Dept of Energy). 

As a case study the starch converting plant was used. Summer wheat mills and starch converts into sugars after liquefaction, fermentation and conversion using corresponding enzymes. Partial starch hydrolysis is performed with a-amylase. The second phase deep hydrolysis is occurs at the present sweet enzymes. 

Mineral matter has been known to enhance the conversion of coal to liquid products (1,2,3). Addition of pyrite, pyrrhotite, and liquefaction residues ( ) to coal has been shown to affect the coal conversion yields and the viscosity of the products (5.). Of all the minerals present in coal, pyrite (and marcasite) are the most important for coal utilization, especially in direct coal liquefaction (1,5). However, one has to remember that under coal liquefaction conditions pyrite rapidly transforms to a nonstoichiometric iron sulfide Fe S(0 x 0.125). It is noted that the sulfur formed as a result of the decomposition of pyrite is able to extract hydrogen from poor donor solvents. The stoichiometry of the pyrrhotite formed from FeSp depends strongly on the partial pressure of H S. 

Thermochemical liquefaction of biomass is basically a simple process whereby it is heated with alkali under pressure at temperatures up to 400 C. This simple procedure converts the biomass to a mixture of gas (2-10%), char (5-40%), and oil (up to 40%), on a weight basis. It is one of several methods available for conversion of biomass to potential liquid fuels, the others being direct heating of dry matter (destructive distillation, pyrolysis) (1), fermentation (or anaerobic digestion) ( ), and gasification (partial oxidation) ( ) followed by liquefaction to methanol. There are variants on all of thesb processes. 

The liquefaction of hydrogen produces 25% P-H2 + 75% 0-H2, and the slow conversion of 0-H2 to P-H2 adds an additional heat source to the storage system. Hence, it is desirable to cmivert the 0-H2 to P-H2 either completely in the liquid state (by adding charcoal) or preferably partially in the precooled gas phase (at 77°K, liquid N2, the equilibrium mixture of H2 vapor, is 60% P-H2) followed by complete conversion in the liquid state. This reduces the losses on storage from 25%/day for 25% P-H2 to 0.02%/day for 98% P-H2. 

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