Continuous mode examples

Consider two hazardous events release of hazardous material to the atmosphere and reactor rupture. The temperature control is the only layer of protection preventing the release of hazardous material, it operates in a continuous mode, and its dangerous failure results in the release. An adequately sized mpture disk does provide a layer of protection for reactor rupture, and in this case the temperature control still operates in continuous mode, and its dangerous failure results in a demand on the rupture disk. The rupture disk operates in low-demand mode. 

No reproduction or networking permitted without iicense from iHS 

---

The third category, cake filters, although well developed in many wastewater treatment applications, are the least developed of the filtration equipment use by the Biotech Industry. In the organic synthesis laboratory sometimes very simple equipment like a funnel and filter paper is used to accomplish this operation. Some other operations used for this filtration step in the lab are more sophisticated, but many are very labor intensive and limit the capacity of the overall production process itself. As a result, there is a need for optimization of the cake filtration equipment used in biotechnology. Cake filtration equipment is available in batch and continuous modes. Following are several examples of cake filtration units ... 

In the field of PI, the transposition of the chemical reaction operation from batch to continuous mode represents a critical point. In this chapter, some examples of HEX reactors, allowing this transposition, have been presented. 

In some cases we may benefit from adopting a semi-continuous mode of operation, e.g. to a batch of one reactant we continuously feed the other reactant, while removing a volatile product continuously. An example where this is advantageous is the production of ethyl-4-pentenoate, CH2=(CH2)3(CO)OEt from allyl alcohol and triethyl orthoacetate, CHs-CfOEt). Continuous addition of allyl alcohol to a batch of triethyl orthoacetate and continuous removal of the produced ethylalcohol (and. some allyl alcohol) by distillation resulted in high yields of the dersired ester ethyl-4-pentenoate. By contrast, if allyl alcohol and triethyl orthoacetate were reacted in a batch-wise manner the product consisted of a 1 1 mixture of the desired ester and the undesired ester (Anderson, 2000, p 279 Bollyn and Wright, 1998). 

For homogeneous base catalyzed processes, reaction conditions are generally at ambient or slightly higher pressure, and a temperature of 65 °C-70 °C, in the presence of approximately 0.5% catalyst, with a 6 1 molar ratio of methanol to oil (Freedman et al, 1986). The process can be operated continuously (Noureddini et al, 1998) or in batch mode. Examples of continuous industrial processes include Ballestra, Connemann CD, and the Lurgi PSI process. 

An example of glucose coupled ketone reduction is the continuous mode reduction using whole (dead) cells of Lactobacillus kefir for the enantioselective reduction of 2,5-hexanedione to (2R,5R)-hexanediol - a popular chiral ligand for... 

Ultrasonic nebulizers have also been employed in continuous flow systems as interfaces between sample preparation steps in the analytical process and detection by virtue of their suitability for operating in a continuous mode. Thus, preconcentration devices have commonly been coupled to atomic spectrometers in order to increase the sensitivity of some analytical methods. An enhancement factor of 100 (10 due to USNn and 10 due to preconcentration) was obtained in the determination of platinum in water using a column packed with polyurethane foam loaded with thiocyanate to form a platinum-thiocyanate complex [51]. An enhancement factor of 216 (12 with USNn and 18 with preconcentration) was obtained in the determination of low cadmium concentrations in wine by sorption of metallic complexes with pyridylazo reagents on the inner walls of a PTFE knotted reactor [52]. One special example is the sequential determination of As(lll) and As(V) in water by coupling a preconcentration system to an ICP-AES instrument equipped with a USN. For this purpose, two columns packed with two different resins selective for each arsenic species were connected via a 16-port valve in order to concentrate them for their subsequent sequential elution to the spectrometer [53]. 

While the droplets are falling down in the continuous dense gas phase, which is moving in countercurrent mode from the bottom to the top, some components are dissolved and carried out as extract into the separator whereas the insoluble part is collected and withdrawn from the bottom of the column as raffinate. This is illustrated in Fig. 2.28 as trickle flow mode. Examples are the deterpenation of citrus oils, the deacidification of vegetable oils, the separation of alcohol and water and the enrichment of carotenes or of EPA- and DHA-fatty acid esters from fish oils. 

Various types of filtration equipment are available commercially and can be operated in batch, semicon-tinuous, or continuous modes. Among the commonly used types are the plate and frame filter, rotary drum filter, leaf filter, plate filter, and tray filter. Apart from the plate and tray filters, all other are enclosed and therefore are easy to work with when sterility of the solids is an important issue. Moreover, all these filters are examples of dead-end filters. Cross-flow filtration is mostly used in the purification stage through membranes with very low pore sizes and is discussed later. 

The use of supercritical fluids to extract the cyclic ethers from the polymerizate is described. In one example it is related that a charge of THF-ethylene oxide polymerizate containing 8% cyclic ethers is contacted in batch continuous mode with propylene at 100 °C and 83 atm. The residual polymerizate contains 2% cyclic ether content. No gas volume is given in this example or in the three other examples with other polymers and copolymers extracted using supercritical ethylene and propylene. Thus, no distribution coefficients can be calculated to determine the potential industrial value of this patent. 

One way of process simplification is to make molecular complex compounds out of much simpler building blocks (e.g., by multi-component one-pot syntheses like the Ugi reaction), at best directly out of the elements. Especially in the latter case, this is often quoted as a dream reaction [14]. Typically, such routes have been realized so far with hazardous elements, easily undergoing reaction, but lacking selectivity. One example is direct fluorination starting with elemental fluorine, which has been performed both with aromatics and aliphatics. Since the heat release cannot be controlled with conventional reactors, the process is deliberately slowed down. While, for this reason, direct fluorination needs hours in a laboratory bubble column it is completed within seconds or even milliseconds when using a miniature bubble column operating close to the kinetic limit. Also, conversions with the volatile and explosive diazomethane, commonly used for methylation, have been conducted safely with microreactors in a continuous mode [14]. 

Mode of operation. There is a vast difference between a set-up that will be used continuously (for example, for high-pressure synthesis) and one which will be used intermittently for a small number of cycles. High-pressure... 

---