Scale commercial units

The most widespread biological application of three-phase fluidization at a commercial scale is in wastewater treatment. Several large scale applications exist for fermentation processes, as well, and, recently, applications in cell culture have been developed. Each of these areas have particular features that make three-phase fluidization particularly well-suited for them Wastewater Treatment. As can be seen in Tables 14a to 14d, numerous examples of the application of three-phase fluidization to waste-water treatment exist. Laboratory studies in the 1970 s were followed by large scale commercial units in the early 1980 s, with aerobic applications preceding anaerobic systems (Heijnen et al., 1989). The technique is well accepted as a viable tool for wastewater treatment for municipal sewage, food process waste streams, and other industrial effluents. Though pure cultures known to degrade a particular waste component are occasionally used (Sreekrishnan et al., 1991 Austermann-Haun et al., 1994 Lazarova et al., 1994), most applications use a mixed culture enriched from a similar waste stream or treatment facility or no inoculation at all (Sanz and Fdez-Polanco, 1990). 

Encouraged by the operating success so far of a pilot plant in Lyons, PCUK is building a small-scale commercial unit there due on stream in 1975- A full scale plant is planned for 1977... 

Recently it has been shown that anhydrous hydrogen fluoride exerts a selective solvent action on sulfur compounds and can be used satisfactorily for the desulfurization of kerosenes. In some respects it behaves similarly to sulfuric acid. Points of difference, however, are that it does not oxidize mercaptans to disulfides and that it can be used over a wide temperature range, 30° to 150° F., without affecting results. Hydrogen fluoride does not yet seem to have been used in full scale commercial units. 

The objective of scale-up in reactor design is to determine a criterion or criteria on which to base the transfer of the laboratory scale into a full-scale commercial unit. Before proceeding from a laboratory to an industrial scale, additional investigations are required. However, it is difficult to define these additional steps to gather all the information as promptly as possibe and at minimum cost. The methodology of process development leading to scale-up becomes the principal factor for the success of the operation. In achieving this purpose, experiments are classified into three main types laboratory, pilot plant, and demonstration units. 

Key advances in this area will continue to be in the development of specialized microscopes utilizing real-time image/data processing and combinations of the optical techniques discussed here. Increasing the reliability and reproducibility of such systems is important. Once developed, engineering systems for widespread use as (a) lab scale commercial units and (b) microscale for portable lab-on-a-chip units will need to occur. 

The Ebex process for ethylbenzene recovery was developed more recently and, although pilot scale operation has been demonstrated, no full-scale commercial unit has yet been built. ... 

The DEZ process was developed by the Library of Congress in Washington over more than 15 years, progressing from simple laboratory experiments to an operating small-scale commercial unit Much of the latter work was in cooperation with Texas Alkyls, one of three major producers of compounds such as diethyl zinc (DEZ). Akzo secured an exclusive Hcense for the DEZ Process and tried to commercialize the technology. 

Although bulk polymerization of acrylonitrile seems adaptable, it is rarely used commercially because the autocatalytic nature of the reaction makes it difficult to control. This, combined with the fact that the rate of heat generated per unit volume is very high, makes large-scale commercial operations difficult to engineer. Lastiy, the viscosity of the medium becomes very high at conversion levels above 40 to 50%. Therefore commercial operation at low conversion requires an extensive monomer recovery operation. 

Most by-product acetylene from ethylene production is hydrogenated to ethylene in the course of separation and purification of ethylene. In this process, however, acetylene can be recovered economically by solvent absorption instead of hydrogenation. Commercial recovery processes based on acetone, dimetbylform amide, or /V-metby1pyrro1idinone have a long history of successfiil operation. The difficulty in using this relatively low cost acetylene is that each 450, 000 t/yr world-scale ethylene plant only produces from 7000 9000 t/yr of acetylene. This is a small volume for an economically scaled derivatives unit. 

Commercially, the burner chamber and the absorber cooler sections are combined as a single unit for small-scale production. However, in large capacity plants, these units are separated. A typical commercial unit is schematically described in Figure 5 (32). 

Phosphoms(V) sulfide, an important commodity in the United States since about 1920, is the dominant commercial material. Phosphoms sesquisulfide, P4S2, has been made commercially since about 1900. Phosphoms heptasulfide was introduced as a small-scale commercial product in 1940. 

Production, Shipment, and Specifications. Carbonyl sulfide is available ia 97% min purity ia cylinders up to 31.8 kg contained weight. It is shipped as a flammable gas. There appears to be no full-scale commercial production of carbonyl sulfide ia the United States. 

Deviations from the ideal frequentiy occur in order to avoid system complexity, but differences between an experimental system and the commercial unit should always be considered carefully to avoid surprises on scale-up. In the event that fundamental kinetic data are desired, it is usually necessary to choose a reactor design in which reactant and product concentration gradients are minimized (36), such as in the recycle (37) or spinning basket reactor designs (38,39). 

Often, a pilot plant will operate in the viscous region while the commercial unit will operate in the transition region, or alternatively, the pilot plant may be in the transition region and the commercial unit in the turbulent region. Some experience is required to estimate the difference in performance to be expected upon scale-up. 

In order to make the pilot unit more like a commercial unit in macro-scale characteristics, the pilot unit impeller must be designed... 

Scale-Up on Rate Filtration rates calculated from bench-scale data shouldbe multiplied by a factor of 0.8 for all types of commercial units which do not employ continuous washing of the filter medium and on which there is a possibility of filter-medium bhnding. For those units which employ continuous filter-medium washing, belt-type drum and horizontal units, the scale-up fac tor maybe increased to 0.9. The use of this scale-up fac tor assumes the following ... 

As far as industrial applications are concerned, the easy scale-up of two-phase catalysis can be illustrated by the first oxo aqeous biphasic commercial unit with an initial annual capacity of 100,000 tons extrapolated by a factor of 1 24,000 (batch-wise laboratory development production reactor) after a development period of 2 years [4]. 

The height of the transfer unit has not been satisfactorily correlated for application to a wide variety of systems. If pilot plant or other acceptable data are available to represent the system, then the height of packing can be safely scaled-up to commercial units. If such data are not available, rough approximations may be made by determining Hg and Hl as for absorption and combining to obtain an Hqg (Ref. 74, pg. 330). This is only very approximate. In fact it is because of the lack of any volume of data on commercial units that many potential applications of packed towers are designed as tray towers. 

The voltage output of the more common types of thermocouple is of the order of 50V/C and the output is either read on a sensitive moving-coil meter or on a digital voltmeter. The reading is converted to temperature using a calibration chart supplied with the thermocouple. Some commercial units are available in which the thermocouple and instrument is supplied as an integral unit with the scale directly calibrated in temperature. If a separate instrument is to be used then it should be noted that the thermocouple resistance is only of the order of 10 and... 

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