Sulfur feed

Because hydrocarbon feeds for steam reforming should be free of sulfur, feed desulfurization is required ahead of the steam reformer (see Sulfur REMOVAL AND RECOVERY). As seen in Figure 1, the first desulfurization step usually consists of passing the sulfur-containing hydrocarbon feed at about 300—400°C over a Co—Mo catalyst in the presence of 2—5% H2 to convert organic sulfur compounds to H2S. As much as 25% H2 may be used if olefins... 

Requirements for desulfurizing the feed are much the same as in the semi-regenerative process. While the continuous regeneration facilities would permit operation with higher sulfur feeds, extensive HjS corrosion results, making feed... 

Our studies show that sulfur feeding in the form of meat also induced greater acid and calcium excretion in the urine than soy. 

Many commercial units 6,14,15 in operation on sulfur feed, or smelter gases containing S02. Process not yet commercially demonstrated for 52 H2S feed... 

For many refineries, switching to a low sulfur feed is both expensive and unrealistic. Feed hydrotreating is the most capital intensive of the available solutions. 

Low sulfur feeds are generally high in cost and hmited in availabihty Very high capital and operating costs... 

Efforts to develop modified Claus processes that will operate with low concentrations of sulfur in the feed gas have been previously mentioned. A similar system is being laboratory tested at IGT which does not require precise, instantaneous control of the oxygen/sulfur feed ratio. 

SO2 components of the process gas stream. None, however, directly attack the problem of removal of other sulfur values in the gas such as CS2, COS and entrained sulfur mist. These sulfur components can easily exceed 1% of the total sulfur feed and failure to remove them from the process stream can frustrate any attempt to achieve 99%+ recovery even when the Claus reactants, H2S and SO2, have been reduced to low ppm levels. 

Plants to process alternate sources of energy will make low-sulfur fuels from high-sulfur feeds such as coal, oil shale, tar sands, or heavy oil. Elemental sulfur will be a normal byproduct. Nearly all processing schemes first produce H2S from the sulfur compounds in the raw material, and then convert H2S to elemental sulfur. Usually this conversion step is labelled "Claus Process". 

Various Methods of Incorporating Sulfur. The generally poorer results for LPG from the sulfur-free system indicated that sulfur should be incorporated at least somewhere in the processing system. To determine whether best results are obtained with sulfiding only, sulfur feed addition only, or both, a series... 

A corollary of the fact that synthetic silica-alumina becomes susceptible to sulfur poisoning when contaminated by metals is that poisoning by metals may be expected to be more serious when processing high-sulfur feeds than with low-sulfur stocks. 

The properties of the feedstocks used for the GSR study are given in Table 1. A low- and mid-sulfur feed was used, besides the different sulfur levels the feeds also showed different crackabilities which was expected from the different K factors. 

The effect of the GSR technology on the sulfur content of the LCO is illustrated in Figure 12. This shows a decrease of approximately 10% sulfur content over the whole conversion range. For this experiment the USY/Matrix system was used on the low sulfur feed. Unlike the gasoline, the LCO shows an increase in the sulfur level with conversion, which is most likely due to a concentration of stable aromatic sulfur compounds in the LCO. 

Sulfur Distribution in Thermal Cracking of High Sulfur Feed Stocks. 

The catalyst is activated through sulfiding, either by high>sulfur feed or treatment. During this process the MoOj layer breaks up into microcrys tal of Mo 2, into which small amounts of cobalt ions are incorporated. 

TEMPERATURE CONDITIONS FOR PROCESS WITH A HYDRAULIC SULFUR FEED SYSTEM ARE SHOWN IN PARENTHESIS... 

Rare earths in SOx and NOx abatement additives for FCC. Sulfur oxides can be formed in the regenerator due to the oxidation of the sulfur compounds contained in the coke. There are four options to abate SOx emissions in FCC units Processing low-sulfur feeds (S < 0.3%), hydrodesulfurization of the feed, flue gas scrubbing, and the use of SOx additives. 

Two centrifugal pumps are generally provided for filtering the raw snlfur. Metering pumps are provided to ensure steady sulfur feed to the burner. This helps in maintaining steady process conditions, very essential for efficient plant operations. 

Indication of sulfur feed rate and air flow rate. 

Cartridge type These were simple on—line strainers having stainless steel screens positioned in a vessel provided in the sulfur feed line to the burner. A bypass line or a parallel standby unit was also arranged. These could become quickly filled up due to their small capacity to hold the sludge, and frequent changeover was necessary. 

These sanbbers are found to be very useful during plant start-up after any long stoppage (during project comnussioning, after annual overhaul, or after any long maintenance breakdown) or when the process is upset—due to excess sulfur feed, disturbed converter temperatures, or a steam leak in the gas stream... 

Oil/gas firing arrangement for initial heating of plant units prior to starting sulfur feeding/commencing production. 

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