Quality of feedstock

These applications avoid the major obstacles for using biomass for electricity generation fluctuation in the supply, and the type of biomass available. Seasonal variations and differing quality of feedstock are the biggest barriers to more widespread use. This is especially true for biomass wastes. 

Fresh catalyst makeup rate should be reduced appreciably, depending upon the quality of feedstock. 

The quality of feedstocks processed in FCC units continues to decline. Therefore more units will reach operating constraints due to larger amounts of coke precursors and metal contaminants. While special process and unit design modifications are developed to handle the processing of these heavier feedstocks highly metal tolerant catalysts are required. 

The choice of which system to use depends on the quality of feedstock being processed and the value of lost production time. 

There are many factors affecting enzymatic transesterification (Fjerbaek et al, 2009 Robles-Medina et al, 2009). Among the key factors are type, stability and reusability of hpase, type of the acceptor alcohol, substrate ratios, quality of feedstocks, reaction temperature, water activity and/or water content. 

The requirement for information on chemical composition extends into most sectors of industry. The chemical measurement analytical market is extremely diverse. Chemical analysis is a key process in drug discovery, in assessing the quality of feedstock materials and end products, in monitoring chemical processes, in demonstrating regulatory compliance, in disease diagnostics, and in environmental conservation. 

Simple conventional refining is based essentially on atmospheric distillation. The residue from the distillation constitutes heavy fuel, the quantity and qualities of which are mainly determined by the crude feedstock available without many ways to improve it. Manufacture of products like asphalt and lubricant bases requires supplementary operations, in particular separation operations and is possible only with a relatively narrow selection of crudes (crudes for lube oils, crudes for asphalts). The distillates are not normally directly usable processing must be done to improve them, either mild treatment such as hydrodesulfurization of middle distillates at low pressure, or deep treatment usually with partial conversion such as catalytic reforming. The conventional refinery thereby has rather limited flexibility and makes products the quality of which is closely linked to the nature of the crude oil used. 

The main difference between gas works and coke oven practice is that, in a gas works, maximum gas yield is a primary consideration whereas in the coke works the quality of the coke is the first consideration. These effects are obtained by choice of a coal feedstock that is suitable to the task. For example, use of lower volatile coals in coke ovens, compared to coals used in gas works, produces lower yields of gas when operating at the same temperatures. In addition, the choice of heating (carbonizing) conditions and the type of retort also play a principal role (10,35). 

Shell Gas B.V. has constructed a 1987 mVd (12,500 bbhd) Fischer-Tropsch plant in Malaysia, start-up occurring in 1994. The Shell Middle Distillate Synthesis (SMDS) process, as it is called, uses natural gas as the feedstock to fixed-bed reactors containing cobalt-based cat- yst. The heavy hydrocarbons from the Fischer-Tropsch reactors are converted to distillate fuels by hydrocracking and hydroisomerization. The quality of the products is very high, the diesel fuel having a cetane number in excess of 75. 

The regenerator has two main functions It restores catalyst activity and supplies heat to crack the feed. The spent catalyst entering the regenerator contains between 0.8-2.5 wt% coke, depending on the quality of the feedstocks. Components of coke are carbon, hydrogen, and trace amounts of sulfur and nitrogen, which burn according to the reactions shown in Table 4-3. 

In conventional alkylation operations, 98 wt. %, sulfuric acid is used as the catalyst, although some processes use HF.The spent alkylation acid, withdrawn as 88-92% acid, is not consumed in the chemical sense, but is diluted by carbonaceous material and small amounts of water. Acid reconditioning is usually completed in a separate plant. The range in makeup acid requirement and in octane quality varies with plant design, with type of feedstock, and with alkylate product rate. A wide variety of feedstocks can be processed through alkylation plants, as both low and high boiling olefins can be alkylated. 

DO is the lowest priced product and the goal is to reduce its yield. The DO s yield largely depends on the quality of the feedstock and the conversion level. Naphthenic and aromatic feedstocks tend to yield more bottoms than paraffinic feedstocks. If the conversion is m the low- to mid-70 s, increasing catalyst-to-oil ratio or using a catalyst with an active matrix can reduce slurry yield. Raising conversion reduces bottoms yield. If the conversion is in the 80 s, little more can be done to reduce bottoms yields. 

Many factors influence delta coke, including quality of the FCC feedstock, design of the feed/catalyst injection system, riser design, operating conditions, and catalyst type. The following is a brief discussion of these factors ... 

Feedstock quality. The quality of the FCC feedstock impacts the concentration of coke on the catalyst entering the regenerator. A heavier feed containing a higher concentration of coker gas oil will directionally increase the delta coke as compared with a lighter, resid-free feedstock. 

As with troubleshooting, a proper debottlenecking exercise must consider the effects of feedstock, catalyst, operating conditions, mechanical hardware, environmental issues, and the ability of the rest of the refinery to handle the additional feed/product rates and quality. 

An RFCC is distinguished from a conventional vacuum gas oil FCC in the quality of the feedstock. The residue feed has a high coking tendency and an elevated concentration of contaminants. 

During the sulfation of alcohol ethoxylates the undesired byproduct 1,4-di-oxane may be formed. Although the formation of 1,4-dioxane is predominantly governed by the sulfation and neutralization conditions and by the chemical composition of the organic feedstock, other factors, such as the quality of the raw material, also contribute. This prompted a reappraisal of the required quality standards for this feedstock. In Table 11 guideline specifications are presented. 

Apart from a few reports" on solid acid catalyzed esterification of model compounds, to our knowledge utilization of solid catalysts for biodiesel production from low quality real feedstocks have been explored only recently. 12-Tungstophosphoric acid (TPA) impregnated on hydrous zirconia was evaluated as a solid acid catalyst for biodiesel production from canola oil containing up to 20 wt % free fatty acids and was found to give ester yield of 90% at 200°C. Propylsulfonic acid-functionalized mesoporous silica catalyst for esterification of FFA in flotation beef tallow showed a superior initial catalytic activity (90% yield) relative to a... 

Typical applications at Polysar included the quantification of residual solvents and monomers in finished rubber products (e.g. styrene in SBR), quality control of feedstocks such as benzene or ethyl benzene as impurities in styrene monomer, and the analysis of samples collected from environmental monitoring programs. 

Resids HDT is carried out at temperatures between 360°C and 450°C, pressures from about 1500 to 3000psig, and 0.2 to lh-1 of space velocity. Graded catalyst beds combining CoMo and NiMo catalysts can be adapted to the quality of the feedstock and depending on whether atmospheric or vacuum residues are going to be treated. HDT of resids is seen as a feedstock pretreatment for preparing feedstock for either mixed with ordinary FCC feeds or for HCK (mixed with VGO or to a resid HCK). The advantages... 

The asphaltenes are selectively converted with a low hydrogen consumption decreasing significantly the metal content in the product. Catalyst was tested during a six-month period, processing various heavy feedstocks and showing a stable performance. The yields and product quality reported indicated almost complete conversion of the feed and total metal removal. The net effect of the ABC pretreatment was found to be an increase in catalyst life, higher metal quality of the product oil, and increase distillate yields. 

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