Sulfur free fuels, solid

Products of Combustion For lean mixtures, the products of combustion (POC) of a sulfur-free fuel consist of carbon dioxide, water vapor, nitrogen, oxygen, and possible small amounts of carbon monoxide and unburned hydrocarbon species. Figure 27-12 shows the effect of fuel-air ratio on the flue gas composition resulting from the combustion of natural gas. In the case of solid and liquid fuels, the... 

Sulfur-free fuel, since solid acid catalysts do not leach into the biodiesel product. 

Solvent-Refined Coal. The solvent-refined coal (SRC 1) process (40) produces a low-sulfur, low-ash solid fuel from coal. Through the courtesy of L. Taylor, samples of SRC produced from five different feed coals were made available to us for ESR studies. Each of the five samples gave a strong ESR resonance near g=2 g values and spectral line widths are summarized in Table II. The g value and line width data, viewed collectively, suggest the presence of organic free radicals, with only minor interaction (except possibly for the Monterey sample) between the unpaired electrons and heteroatoms in the samples. 

In order to handle this group of solid fuels, they ignore the bond availability of sulfur in the fuel that is, they treat sulfur as a free species. Next they calculate the difference between sulfur s chemical availability and its lower heating value, given by... 

Liquors from Neutral Semichemical Pulping and from Kraft Pulping. In making neutral sulfite semichemical pulp, the black liquors may have about 10 parts of water to 1 part of total solids, of which about one-third is sodium acetate and sodium formate. After evaporation to about 1 part solids to 1 part water, sulfuric acid is added to the concentrate to free the acetic and formic acids. When the concentrate is extracted with acetone, the mixed acids are obtained, the acetone is separated for recycle, and the acids are concentrated and refined. The raffinate is stripped and is passed to the usual furnace to be burned for recovery of the inorganic salt values. This process gives a smelt of sodium sulfate, which may be used in the kraft process as chemical makeup. The loss of the fuel value of the acetic and formic acids is practically negligible. 

The reaction products from the fuel must be gaseous so that they can be directly vented to the air. This eliminates the requirement for hardware to collect, store and return the spent solid or liquid reaction products. The product of the reaction of hydrogen with oxygen, from the air, is water. There is no carbon so no un-bumed hydrocarbons or toxic carbon monoxide is produced. All fossil fuels contain some amount of sulfur compounds. These are converted to sulfur dioxide when the fuel is burned. Most processes under consideration for the production of hydrogen are free from sulfur or any other harmful contaminants. Thus, unlike fossil fuel hydrocarbons, hydrogen combustion products will not be contaminated with sulfur compounds. 

Feedstocks. Feedstocks for the oil-fumace process are heavy fuel oils. Preferred oils have high aromaticity, are free of suspended solids, and have a minimum of asphaltenes. Suitable oils are catalytic cracker residue (once residual catalyst has been removed), ethylene cracker residues, and distilled heavy coal tar fractions. Other specifications of importance are freedom from solid materials, moderate to low sulfur, and low alkali metals. The ability to handle such oils in tanks, pumps, transfer lines, and spray nozzles is also a primary requirement. 

The condensate from the dual condensers is collected into storage tanks and is free from solid particles and water (H2O). Sometimes, based on the input, a product similar to fuel oil may be obtained but with lower quality. Generally, these fuels have a lower sulfur content compared with distillate fuels. 

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