Feed quality

Nearly every chemical manufacturiag operation requites the use of separation processes to recover and purify the desired product. In most circumstances, the efficiency of the separation process has a significant impact on both the quality and the cost of the product (1). Liquid-phase adsorption has long been used for the removal of contaminants present at low concentrations in process streams. In most cases, the objective is to remove a specific feed component alternatively, the contaminants are not well defined, and the objective is the improvement of feed quality defined by color, taste, odor, and storage stability (2-5) (see Wastes, industrial Water, industrial watertreati nt). 

The thermal quality of the solvent feed has no effect on the value of (S/F)mjn, but does affect the minimum reflux to some extent, especially as the (S/F) ratio increases. R nax occurs at higher values of the reflux ratio as the upper-feed quality decreases a subcooled upper feed provides additional refluxing capacity and less external reflux is required for the same separation. It is also sometimes advantageous to introduce the primary feed to the extractive distillation column as a vapor to help maintain a higher solvent concentration on the feed tray and the trays immediately below... 

Improve feed quality by using selected scrap to reduce the release of pollutants to the environment. 

Because some hydrocracking occurs, Powerforming also produces saturated C to Q light hydrocarbons. The methane and ethane formed normally are consumed as refinery fuel. Propane and butane products are frequently marketed as LPG. The relative quantities of each of these products vary considerably with feed quality, operating conditions and octane severity. 

The extent to which each of the above reactions occur is strongly influenced by feed quality and the levels selected for the major process variables pressure, temperature, recycle rate, and frequency of regeneration. From a process viewpoint, these variables affect catalyst requirement, gasoline yield, and coke make. 

There are several versions of the two-step process. One involves the use of 5A molecular sieves in conjunction with Powerforming. In this combination process, the 5A sieves may be used to remove n-paraffms from the feed to improve feed quality. Alternatively, the Powerformate may be sieved to remove the low octane n-paraffm components. Extraction of aromatics from Powerformate is another interesting two-step process. 

The choice of partial versus full combustion is dictated by FCC feed quality. With clean feed, full combustion is the choice. With low quality feed or resid, partial combustion, possibly with heat removal, is the choice. 

Feed characterization relates product yields and qualities to feed quality. Knowing the effects of a feedstock on unit yields, a refiner can purchase the feedstock that maximizes profitability. It is not uncommon for refiners to purchase raw crude oils or FCC feedstocks without knowing their impact on unit operations. This lack of knowledge can be expensive. 

The two primary factors that affect feed quality are ... 

Sulfur Content of Coke vs. Hydrotreated FCC Feed Quality... 

When using ZSM-5, there is almost an even trade-off between FCC gasoline volume and LPG yield. For a one-number increase in the research octane of FCC gasoline, there is a 1 vol% to 1.5 vol% decrease in the gasoline and almost a corresponding increase in the LPG. This again depends on feed quality, operating parameters, and base octane. 

The regenerator dense phase temperature (see Figure 8-7) can be adversely affected by the feed quality, the condition of the catalyst, the operating variables, and the mechanical conditions of the unit ... 

The performance of the unit is a function of feed quality, catalyst properties, operating variables, and the mechanical condition of the unit. The indicators used to measure the unit s performance are ... 

True conversion is affected by feed quality, catalyst, operating variables, and mechanical conditions (Figure 8-11 A). 

Optimization refers to maximizing feed rate and/or conversion with the existing equipment while reaching as many constraints as possible. It can be the response to changes in the feed quality, ambient conditions, or the market demands. Although it is not discussed separately here, it is the incentive for most debottlenecking projects. 

Evaluation of the interaction among feed quality, catalyst properties, and operating conditions... 

CH4 emitted from manure depends primarily on (i) the management system such as solid disposal system, liquid disposal systems, e.g., ponds, lagoons, and tanks, which can emit up to 80% of manure-based CH4 emissions, while solid manure emits little or no CH4. (ii) Environmental conditions are also important. The higher the temperature and moisture, the more CH4 produced, (iii) CH4 emissions also depend on the quantity of the manure produced, which depends on the number of animals housed, the amount of feed the consumed, and the digestibility of the feed, (iv) Manure characteristics depend on the animal type, feed quality, and rumen microbes present in the rumen and digestive tracks. Manure handled in liquid form tends to release more amount of CH4 when compared to solid or manures thrown into the pasture, which do not decompose anaerobically. High temperatures with neutral pH and high moisture content enhance CH4 production [45],... 

The removal of PhCs by NF membranes occurs via a combination of three mechanisms adsorption, sieving and electrostatic repulsion. Removal efficiency can vary widely from compound to compound, as it is strictly correlated to (a) the physicochemical properties of the micro-pollutant in question, (b) the properties of the membrane itself (permeability, pore size, hydrophobicity and surface charge) and (c) the operating conditions, such as flux, transmembrane pressure, rejections/recovery and water feed quality. 

The selection of steam cracker feedstock is mainly driven by market demand as different feedstock qualities produce different olefins yields. One of the commonly used feed quality assessment methods in practice is the Bureau of Mines Correlation Index (BMCI) (Gonzalo et al., 2004). This index is a function of average boiling point and specific gravity of a particular feedstock. The steam cracker feed quality improves with a decrease in the BMCI value. For instance, vacuum gas oil (VGO) has a high value of BMCI and, therefore, is not an attractive steam cracker feed. The commonly used feedstocks in industry are naphtha and gas oil. 

Tables 2.1 and 2.4 show the VGO-C feed quality properties and the test conditions of the Riser Simulator experiments. The three catalysts tested were the same ones used in the FFB reactor experiments. Temperature for the LZM catalyst was lower than for the other catalysts to reproduce typical conditions used for mid-distillate maximization in commercial units.

The additional coke related with feed quality is a function of their Conradson carbon content. According to the literature, our results show that this coke is the most refractory and consequently is located in the highest temperatures range ( 700°C-716°C). Furthermore, it shifts to higher temperatures as the content of CCR of feedstock increases. 

Total unit heat dnty will typically be in the range of 500-1000 BTU per pound of feed to the unit. This set of process heat requirements establishes the amount of heat that must be supplied by combustion of coke. Because of the process control schemes that are normally employed in FCCUs, the unit operation will automatically adjust itself so that the energy produced via coke combustion equals the heat requirements of the process. If the balance is shifted by changes to the feed quality or operating conditions, shifts in catalyst circulation rate and regenerator temperature will occur until a new equilibrinm set of conditions is established. 

Feed quality is the most significant factor affecting SO, emissions from an FCCU. The sulfur content and the particular sulfur species present in the feed strongly determine the extent of potential SO, emissions [2], Typically, about 10% of the sulfur in feed goes to SO, but it can vary from 5 to 30 wt% (Figure 16.1). 

With the currently available systems for PCR-based detection and identification, however, qualitative information about the presence or absence of a certain fimgus can be obtained and this should be used to advantage in food and feed quality control because the technology has the power to provide insights into the mycotoxigenic potential of analyzed samples. This information can then be used in order to decide whether samples should proceed down the process of production or should be retained for further analysis of mycotoxins. PCR-based multiplex systems... 

For commercial simulations, KINPTR s selectivity kinetics determine the reformate composition and overall yield at a target reformate octane. Reformer yield-octane behavior from pilot and commercial units are shown in Fig. 29a. The large variation in the reformate yields at a given octane, as much as 25%, results from the wide range of process conditions and naphtha feed quality used in Mobil reformers. As demonstrated in Fig. 29b, KINPTR accurately normalizes these reformate yields over a wide range of octanes, including those required for gasoline lead phaseout. 

Hydrogen produced, standard cu. ft./bbl. feed Quality, 100% C hydroformate Benzene, vol. %... 

Thus, some load variables can be eliminated by the application of guideline (i) to Fig. 7.9, e.g. it is relatively easy to maintain the feed quality by installing a preheater with the outlet temperature controlled as shown, and the feed flow can be fixed by using a simple flow control loop (as long as intermediate storage is provided between the distillation plant and any plant upstream which supplies the feed to the column). 

Equation 7.32 takes into account the variations in feed, vapour and liquid rates on the column vapour and liquid flows. The feed quality qF is assumed to remain constant (qF is the fraction of the feed which flows down the column as liquid). 

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