Bench-scale device

It is important to keep in mind that an MFC has never been used at any scale larger than the bench-scale devices used in laboratory tests, and so at this time we have no specific data on system performance in the manner needed to specify unit processes and system... 

Following the arguments given above, micro mixers are valuable tools for bench-scale continuous processing to fill the recycle loop. For first tests on feasibility, the total volume of the recycle loop has to be kept small, demanding also for small-scale processing units. Conventional devices would probably suffer here from too large internal volumes. 

Aqueous, alkaline fuel cells, as used by NASA for supplemental power in spacecraft, are intolerant to C02 in the oxidant. The strongly alkaline electrolyte acts as an efficient scrubber for any C02, even down to the ppm level, but the resultant carbonate alters the performance unacceptably. This behavior was recognized as early as the mid 1960 s as a way to control space cabin C02 levels and recover and recycle the chemically bound oxygen. While these devices had been built and operated at bench scale before 1970, the first comprehensive analysis of their electrochemistry was put forth in a series of papers in 1974 [27]. The system comprises a bipolar array of fuel cells through whose cathode chamber COz-containing air is passed. The electrolyte, aqueous Cs2C03, is immobilized in a thin (0.25 0.75 mm) membrane. The electrodes are nickel-based fuel cell electrodes, designed to be hydrophobic with PTFE. 

A bench-scale settler was used in an experimental study to assess continuous biodesulfurization operation to separate oil and water + biocatalyst [260], The design was based on a viton tubing settler surface placed at an angle to allow separation of the multi phase mixture. The device was reported to operate with over 95% efficiency for first 24 hours after which the performance reduced drastically. 

BENCH-SCALE APPARATUS. Laboratory combustion devices include flame-plate, pot-burner, and Institute of Petroleum Technology (IPT) wick-lamp apparatus. Small-scale combustors could be considered laboratory equipment, but results obtained... 

The UL 94 standard specihes bench-scale test methods to determine the acceptability of plastic materials for use in appliances or other devices with respect to flammability under controlled laboratory conditions. The test method that is used depends on the intended end-use of the material and its orientation in the device. The standard outlines two horizontal burning tests, three vertical burning tests, and a radiant panel flame spread test. The most commonly used test method described in the UL 94 standard is the 20-mm Vertical Burning Test V-0, V-l, or V-2. The method is also described in ASTM D 3801. A schematic of the test setup is shown in Figure 14.3. 

Adsorbers are one type of several control devices available for treating gaseous wastes/pollutants. A gas mask can be viewed as a bench-scale version of an industrial adsorber. 

Lab-on-a-chip systems have been previously demonstrated to have significant utility in the field of analytical chemistry.1 Lab-on-a-chip systems miniaturize standard bench-scale operations that are normally carried out in containers of the order of millilitres or litres to chip-scale operations in channels and droplets on the order of nanolitres to microlitres. The majority of lab-on-a-chip devices proposed thus far utilize micrometer-scale sealed channels. These sealed channels can then be used to separate, combine and mix chemical reagents in such a way as to recreate traditional wet chemistry protocols on a much smaller scale. When used in such a manner, these sealed channels are referred to as continuous flow microfluidic channels.2 4... 

Some solvent-extraction techniques are relatively difficult to effect using conventional laboratory apparatus. For example, the classical penicillin G extraction in which acidified broth is contacted with a water-immiscible solvent can only be operated effectively using continuous-flow methods because of the poor stability of the product at low pH values. This extraction can be reproduced on the bench scale using the AKUFVE apparatus, which was designed for extraction studies in the nuclear industry (12,13). Selective extraction may involve the use of a solvent in which the product has a poor partition coefficient. Countercurrent extractors are mostly process scale devices but the smallest four-stage extractor produced by Robatel could be considered a bench scale. It has a throughput of 50-100 mL/min. 

Modem reaction calorimetry is the method of choice for the experimental characterization of normal operating conditions. Today, such measuring devices are available commercially as well as self-made in many different designs and their description can be found in the literature [e.g. 60,61,62,63]. The key input to this development was given by Regenass 1979, when he developed the first so-called bench-scale calorimeter [64]. 

As mentioned above, the dosage of sodium hydrosulfite is governed by the concentration of selenium. This operating condition was established as a result of the bench-scale and pilot-scale test work. For each batch, the operator is required to collect a sample at the outlet of the first stage reactor and to obtain a laboratory determination of the selenium concentration. Alternative instrumentation and control techniques are being investigated, which would allow, in the near future, the replacement of the current manual estimation of the selenium level with an automated device. 

As mentioned in Section 3.7, CE and CEC are not used on a routine basis when ultimate performance (accuracy and precision etc.) is required for tme trace level quantitative analysis of small molecules using mass spectrometry. Direct coupling of bench scale CEC (and CE to some extent) to MS is not straightforward. However, both CE and CEC are key technologies for development of integrated lab-on-a-chip devices (Section 4.4.7) and this is the reason for the following discussion. 

In general the synthesis of colloidal and monodispersable nanomaterial with refined functional properties was undertaken to fabricate a cost-effective devices by retaining the functional properties during the synthesis at the bench scale and then scale up to the production level gives a new push to basic and applied research for better understanding the surface functionality. 

In the present day a different scale-up procedure is usually followed. Various aspects of the chemical reaction are studied extensively in very small but often continuously operating bench scale reactors and in "mini-plants , equipped with very accurate measuring devices. Specific physical effects are studi in the absence of chemical reaction on larger scales. Mathematical models are developed that will describe the process accurately as a function of scale, so that they can be extrapolated with confidence to predict the behaviour of larger equipment. 

Machado, M.B. and Kresta, S.M. (2013) The confined impeller stirred tank (CIST) a bench scale testing device for specification of local mixing conditions required in large scale vessels. Chem. Eng. Res. Des., 91 (11), 2209 -2224. 

Typical Example of a Flammability Test. The UL 94 standard provides procedures for bench-scale tests to determine the acceptability of plastic materials for use in appliances or other devices with respect to flammability under controlled laboratory conditions. The standard includes several test methods that are employed depending upon the intended end use of the material and its... 

Over the past decade, there has been a broad effort in the scientific community to miniaturize chemical systems via microfluidic platforms. The concept is to construct compact devices with integrated modular functionalities [42]. These micrometer-sized modules can perform functions that are analogous to bench-scale laboratory processes, hence the name, lab-on-a-chip. For making droplets, a lab-on-a-chip microfluidic device could be envisioned to have the following modules ... 

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