Feeds water content

Feed water content < lOppmw NOx emissions < 50kg/yr Production rate < 400,000 metric tons per year... 

Figure 9.7. C02 permeability versus water content on the sweep side (feed water content = 41 mol%...

Feed Water Rate (cc/min) Feed Water Content (mol%) Pcol (Barrer) a (C02/H2)... 

The water content on the feed side also had significant effects on C02 permeability and C02/H2 selectivity. As shown in Table 9.2 for 120°C, both C02 permeability and C02/H2 selectivity increased as the feed water content increased. This might be caused by the higher water retention in the membrane with the higher water content on the feed side. Consequently, the C02 transport was enhanced by the increased mobility of both mobile and fixed carriers and the C02-carrier reaction rates, while the transport of H2 was not affected significantly. 

Table 9.14 shows the values of the main operating variables in keeping the top and bottom product purity at their specifications under various feed composition conditions. In this table, the operating conditions are not unique for feed water contents from 10% to 60%. For these feed composition cases, there are three degrees of freedom (extra one is the aqueous reflux) for the system with only two product purity specifications. The ones included in the table are the operating conditions that minimize reboiler heat duty by varying aqueous reflux flowrate. 

Pervaporation was next carried out to test the selectivity of polyaniline membranes toward acetic acid-water mixtures. Different feed ratios of acetic acid and water were pervaporated through both undoped and doped polyaniline, as shown in Fig. 33.18, where the feed water content is plotted versus the permeant water content. For comparison the vapor-liquid equilibrium curve for acetic acid-water [78] is plotted just above the line of no separation. From Fig. 33.18 it is clear that undoped polyaniline has a small preference for permeating water over acetic acid at essentially any composition. However, this small preference at an average water permeability of about 0.5 g mm/(m--h) is too low to have any utility. More interesting is fully HCl-doped polyaniline, which permeates water over acetic acid in a much more selective fashion. In fact, even with a mixture of 859f acetic acid-15% water, at least 93 wt % of the permeant was water. It should be pointed out that when undoped membranes are used in the presence of acids, they will partially dope the polyaniline, the extent depending on the pH of the acid used. However, when a... 

The permeability of the fully HCl-doped polyaniline membrane of Fig. 33.18 is shown in Fig. 33.19. Here the feed water content is plotted versus the permeability in gram-millimeters per square meter per hour fg mm/ (m h)]. The lower curve indicates the permeability of acetic acid, the middle curve represents the permeability of water, and the upper curve is the overall combined permeability. Clearly the acetic acid permeability of doped polyaniline is exceedingly low except when pure acetic acid is used. Water permeability increases from 0.23 g mm/(m h) at 15 wt % water content in the feed to >1 g mm/(m h) when pure water is the feed. The total permeability essentially parallels the water permeability. 

Low feed water content of less than 10 wt.% to minimize water in the liquid product ... 

Permeating Gas Water content in feed Water content in permeate ... 

All process Hcensors also feature wastewater treatment systems. Stamicarbon guarantees the lowest NH —urea content and has plants in operation confirming the low NH —urea (1 ppm NH —1 ppm urea). This water is very satisfactory to use as boiler feed water. See Figures 16 and 17 for this system. 

Shell process. Universal Oil Pro-ducts sulfolane sulfolane selectivity and capacity insensitive to water content caused by steam-stripping during solvent recov-ery heavy paraffinic countersolvent use 120 rotating-disk contactor, up to 4 m in diameter the high selectivity and capacity of sulfolane leads to low solvent-feed ratios, and thus smaller equip-ment... 

Particular drawbacks of using alkylsiHcon and alkyltin haHdes with AlCl for the cationic polymerization of terpenes are low yields and the fact that they require rigorously dried feeds (<50 ppm H2O) to be effective. Increased water content results in lower yields and lower softening points (85). Catalyst systems comprised of AlCl with antimony haHdes in the presence or absence of a lower alkyl, alkenyl, or aralkyl haHde are particularly effective in systems containing up to 300 ppm H2O (89,90). Use of 2—12 wt % of a system composed of 2—3 parts AlCl, 0.7—0.9 parts SbCl, and 0—0.2 parts of an organic... 

This reaction is first conducted on a chromium-promoted iron oxide catalyst in the high temperature shift (HTS) reactor at about 370°C at the inlet. This catalyst is usually in the form of 6 x 6-mm or 9.5 x 9.5-mm tablets, SV about 4000 h . Converted gases are cooled outside of the HTS by producing steam or heating boiler feed water and are sent to the low temperature shift (LTS) converter at about 200—215°C to complete the water gas shift reaction. The LTS catalyst is a copper—zinc oxide catalyst supported on alumina. CO content of the effluent gas is usually 0.1—0.25% on a dry gas basis and has a 14°C approach to equihbrium, ie, an equihbrium temperature 14°C higher than actual, and SV about 4000 h . Operating at as low a temperature as possible is advantageous because of the more favorable equihbrium constants. The product gas from this section contains about 77% H2, 18% CO2, 0.30% CO, and 4.7% CH. ... 

Operating parameters of this German plant, on the basis of one cubic meter of raw gas, iaclude 0.139 m O2, 0.9 kg briquettes, 1.15 kg steam, 1.10 kg feed water, 0.016 kWh, and 1.30 kg gas Hquor produced. Gasifier output is 1850 m /h and gas yield is 1465 m /t dry, ash-free coal. The coal briquettes have a 19% moisture content, 7.8% ash content (dry basis), and ash melting poiat of 1270°C. Thermal efficiency of the gas production process is about 60%, limited by the quaHty and ash melting characteristics of the coal. Overall efficiency from raw coal to finished products is less than 50%. 

Solid-Bed Caustic Treatment. SoHd-bed caustic units utilizing methanol [67-56-1] injection into the LPG feed stream can be used for carbonyl sulfide removal. The methanol—caustic solution must be drained periodically from the beds and discarded. When the soHd bed is exhausted, the spent caustic must be discarded and replaced. The LPG from the treater has a low enough water content to meet the propane specification. 

Concentration. Evaporation procedures depend on the concentration of the solution produced during neutralization and the water content required for the subsequent production of soHd product. Neutralizer solutions can contain as Httle as 2% and as much as 25% water feeds to drum granulators can contain 5% water, prill towers 0.3 to 0.5% water. 

The principal reactions are reversible and a mixture of products and reactants is found in the cmde sulfate. High propylene pressure, high sulfuric acid concentration, and low temperature shift the reaction toward diisopropyl sulfate. However, the reaction rate slows as products are formed, and practical reactors operate by using excess sulfuric acid. As the water content in the sulfuric acid feed is increased, more of the hydrolysis reaction (Step 2) occurs in the main reactor. At water concentrations near 20%, diisopropyl sulfate is not found in the reaction mixture. However, efforts to separate the isopropyl alcohol from the sulfuric acid suggest that it may be partially present in an ionic form (56,57). 

Probably more relevant to the chemical industry is the scale-up of thickeners. Thickeners are basically gravity settling tanks that, apart from producing a clear overflow, are designed to have a thick underflow with as Htfle water content as possible. The feed into a thickener is generally more concentrated than the feed into a clarifier, and quite often exhibits zone-settling behavior because of the appHcation of flocculants. 

Oxygen Control. To meet industrial standards for both oxygen content and the allowable metal oxide levels in feed water, nearly complete oxygen removal is required. This can be accompHshed only by efficient mechanical deaeration supplemented by an effective and properly controlled chemical oxygen scavenger. 

In this process the addition of water vapor to the sweep stream can be controlled so that the water activity of the gas phase equals that of the beverage. When this occurs, there is no transport of water across the membrane. The water content of both the beverage feed and the sweep stream is kept constant. These conditions must be maintained for optimum alcohol reduction. The pervaporation system controls the feed, membrane, airstream moisture level, and ethanol recovery functions. An operational system has been developed (13). 

The required desiccant weight is a function of several factors the water removal requirements (mass/time), the cycle time, the equiUbrium loading of water on the desiccant at the feed conditions, the residual water loading on the desiccant after regeneration, and the size of the mass-transfer zone of the desiccant bed. These factors, in turn, depend on the flow rate, temperature, pressure, and water content of both the fluid being dried and the regeneration fluid (see Adsorption, gas separation). 

In the feed preparation section, those materials are removed from the reactor feed which would either poison the catalyst or which would give rise to compounds detrimental to product quality. Hydrogen sulfide is removed in the DBA tower, and mercaptans are taken out in the caustic wash. The water wash removes traces of caustic and DBA, both of which are serious catalyst poisons. Also, the water wash is used to control the water content of the reactor feed (which has to be kept at a predetermined level to keep the polymerization catalyst properly hydrated) and remove NH3, which would poison the catalyst. Diolefins and oxygen should also be kept out of poly feed for good operation. 

Data regarding relief valves, feed and expansion cisterns, etc. are given in Tables 27.11 and 27.12. Cistern sizes shown in Table 27.12 are based on typical system designs and are approximate only. An estimate of the water content of the particular system should always be made where there is any doubt regarding these typical data, to ensure that the cistern capacity is adequate to contain the expansion volume. 

Studies of the incineration of liquid and solid wastes must determine the rates at which hazardous compounds are released into the vapor phase or are transformed in the condensed phase, particularly when the hazardous materials make up a small fraction of the liquid burned. We must be particularly concerned with understanding the effects of the major composition and property variations that might be encountered in waste incinerator operations—for example, fluctuations in heating value and water content, as well as phase separations. Evidence of the importance of variations in waste properties on incinerator performance has been demonstrated by the observation of major smges in emissions from rotary-kiln incinerators as a consequence of the rapid release of volatiles during the feeding of unstable materials into the incinerator. 

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