Abstract: A method for inhibiting the formation of clathrate hydrates in a fluid having hydrate-forming constituents involves treating the fluid with an inhibitor comprising a substantially water soluble polymer having a polymer backbone .with a pendant C.sub.1 --C.sub.3 alkyl group; the polymer having an average molecular weight between about 1,000 and about 6,000,000. Preferably, the pendant alkyl group is a methyl group. The rate of nucleation, growth, and/or agglomeration of gas hydrate crystals in a petroleum fluid stream Is reduced using the alkylated polymer backbone inhibitor, thereby inhibiting the formation of a hydrate blockage in the pipe conveying the petroleum fluid stream. Test results are disclosed which unexpectedly show that alkylating the polymer backbone with a methyl group will produce a subcooling for the alkylated polymer that is at least about 2.degree. F. (about 1.1.degree. C.) greater than its nonalkylated counterpart.

Abstract: A method for inhibiting the formation and/or agglomeration of clathrate hydrates in a petroleum fluid stream containing water is disclosed. The disclosed method uses predetermined inhibitors having a guest group, a polymer backbone, and an anchor group positioned between the guest group and the polymer backbone. The inhibitor predetermination method comprises selection of the polymer backbone, anchor group and guest group using several types of criteria. The polymer backbone should produce a substantially water soluble polymer in combination with the anchor group and the guest group. The anchor group should be a hydrophilic moiety with between one and four hydrogen bonding atoms. The guest group should be either a hydrophobic or amphiphilic moiety with a carbon atom to heteroatom ratio greater than or equal to about two to one and an average van der Waals diameter between about 3.8 angstroms and about 8.6 angstroms.

Abstract: A coal or similar carbonaceous fuel is selectively freed of sodium by water washing it and ion exchanging the washed coal with a strong aqueous electrolyte solution which is substantially free of sodium ions and contains a kind and concentration of ions which are correlated with the composition of the coal to cause a selective removal of ion-exchangeable sodium from the coal, with at least a significant proportion of the ion-exchanging being conducted within a pipeline.

Abstract: Coal can be freed of ion-exchangeable sodium by contacting it with aqueous solutions of CO.sub.2 or formic or acetic acids at a mine mouth or contacting it with aqueous CO.sub.2 while transporting it in a pipeline.