Methods of Operation

Although simple and rectified batch distUlation are the methods most used in the laboratory, they are not the only ones. Procedures employed mainly in industry have also been added to the laboratory repertoire. In order to increase output, semi-continuous and continuous processes have been adopted, whilst in certain cases partial condensation also presents advantages. 

Consider the following single-stage cocurrenr contacting process  

To reduce the degree of curvature of foe operating line, foe use of mote or mass ratios often is preferred to mole or mass fractions. This conversion is accomplished by taking foe ratio of foe number of moles or mass of a transferring spectea to the number of motes or mass of those components that do not transfer  

A similar expression can be written for stream B. A component balance can be used to derive an operating line expression in terms of mole or mass ratios  

FIGURE 4.1-1 Operating diagram single-stage device. 

To maximize driving foross thraaghout a particular system, countercurrent contacting is frequently used. In this coniecling mode, the inlet slrcum for one phase is mixed with the outlet stream of the other phase. For the two-stage countercurrent contacting system, 

A steady-state material balance can be used to track the separation takmg place in the process. As a simplification, only the transfer of a smgle componem will be considered. Taking into account only the bulk-averaged compositions of the flows mto and out of the stage, we can make the foilowmg balances  

Consider the followijig angle-stage cocurrent contacting process  

The cqierating line is theiefoie a straight line passii thnw points (Xi , Kq) and (X,. K ) with a slope of —BJA All points in die angle-stage device must satisfy the material balance and lie on the operating line, although their position on the operadng line is a fum ion of the conditions and related phenomena of the separation process of interest. 

---

The carbide route is the preferred method of operation for most industrial gas operations. It is well suited to small-scale consumers. The high cost of acetylene in industrial gas appHcations reflects these scale, handling, and shipping factors. 

The use of fixed bed catalysts is described in several patents (33—37). Methods of operation include upflow, trickle bed, and even vapor phase. Typically, a large volume of solvent is used to moderate the temperature rise associated with the high heat of reaction for nitro group reduction. 

Improvements to the methanol reductant processes may be found in the patent Hterature. These include methods of operation to reduce acidity in the crystallisation 2one of the generator to promote crystallisation of sodium sulfate and to reduce sulfuric acid consumption (48). Other improvements sought are the elimination of formic acid and chlorine impurities from the chlorine dioxide, as weU as methods of recovering acid and sodium hydroxide, or acid and neutral sodium sulfate from the soHd sodium sesquisulfate salt waste stream (48—52). 

The Idea/Expression Dichotomy. Copyright protects the expression of ideas, but not ideas themselves. Thus copyright will not protect any procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied (7). 

Whatever the mechanism and the method of operation, it is clear that the leaching process will be favored by increased surface per unit volume of sohds to be leached and by decreased radial distances that must be traversed within the solids, both of which are favored by decreased particle size. Fine solids, on the other hand, cause slow percolation rate, difficult solids separation, and possible poor quahty of sohd product. The basis for an optimum particle size is estabhshed by these characteristics. 

Solenoid magnetic separators are designed for batch-type, cyclic, and continuous operation. Devices which can use matrices of expanded metal, grooved plates, steel balls, or filamentaiy metals have been designed. Continuous separators with capacities to 600 t/h for iron ores (similar to the Brazilian hematite) are commercially available (Sala International Inc.). Selection of the method of operation is apphcation-dependent, being based on variables such as temperature, pressure, volume of magnetics in the feed, etc. 

Solid-wa.ste-filling plan. The specific method of filling will depend on the characteristics of the site, such as the amount of available cover material, the topography, and local hydrology and geology. To assess future development plans, it will be necessary to prepare a detailed plan for the layout of the individual solid-waste cells. On the basis of the characteristics of the site or the method of operation (e.g., gas recovery), it may be necessaiy to incorporate special features for the control of the movement of gases and leachate from the landfill. 

The standard requires quality planning to be documented in a format to suit the supplier s method of operation. 

As seen in Chapter 7, the operation of bateh erystallizers is inherently unsteady-state. Transient values oeeur of the major operating variables sueh as slurry density, supersaturation, temperature and mean partiele size. Methods of operational eontrol sueh as by use of seeding and temperature programming were also eonsidered in detail. 

Section 3.2 discusses similar incidents. Rather than blame workers who make mistakes or disobey instructions, we should try to remove the opportunities for error by changing the work situation, that is, the design or method of operation. 

It is no use telling the operator to be more careful. We have to recognize that the possibility of an error—forgetting to open the valve—is inherent in the work situation. If we want to prevent an error, we must change the work situation. That is, change the design and/or the method of operation—the hardware and/or the software. 

If so, can we prevent no flow (or protect against the consequences) by changing the design or method of operation ... 

Under certain situations, for specific equipment configurations, it may be possible to safely operate above the NFPA limit of 60% of the LFL. If this method of operation is to be considered, system-specific test data should be generated which demonstrates dial the combusdble concentradon can be controlled in a safe manner, and only then in consultadon with appropriate company and (where required) regulatory authorities. 

It is common practice that procedures and job-aids are often developed either by plant manufacturing companies or process designers with minimal participation by the end-users, usually plant workers. This has led to situations where the indicated sequence of actions was incompatible with the way the job is done in practice. This presents great problems for the workers who will have to reconcile a potential violation of procedures with a well established method of operation. 

Operating mode The method of operating equipment. See alternating mode, standby mode, rutming mode. 

In all cases it is important to describe the system, its requirements, control and method of operation in the specifications. The manufacturer needs complete data concerning the motive steam (air or water) and the condensable and non-condensable vapors. 

For speed ranges of 3 to 1 or greater, adjustable-voltage operation is recommended. The adjustable-voltage drive usually includes a motor-generator set to supply an adjustable voltage supply to the armature of the drive motor. With this method of operation, a speed range of 10 to 1 readily obtained. 

No alarm system, however well planned and installed, can be completely reliable or tamperproof. The successful operation of a security system requires the active cooperation of those involved in carrying out the necessary procedures carefully and thoroughly. The usefulness of the whole system can be jeopardized by lack of care or inadequate attention to routine procedures in maintenance and servicing. This care has to be extended to the security of keys and of information regarding the system, its installation and method of operation. 

The durability of a building (i.e. its life expectancy and its resistance to deterioration) is determined by deliberate design decisions relating to stmcture and choice of materials as much as to the natural or precipitate process of ageing. Within certain limits, the design of an industrial building can and should take into account the predicted use or lifespan of the process or method of operation which it is to accommodate. To aim at durability beyond that has ascertainable cost implications. These may be acceptable if the building is to serve future known or even unpredictable purposes. 

One method of operating a non-chlorinated supply safely is to ensure that the line runs constantly to waste, as do very old drinking fountains. This avoids biological growth that can accumulate in stagnant water. Dead legs in the piping system are always undesirable, especially in such cases. 

Directional control valves may be operated by differences in pressure acting on opposite sides of the valve elements or may be positioned manually, mechanically, or electrically. Often two or more methods of operating the same valve will be used in different phases of its action. 

The guidance notes can be produced either as a composite handbook containing task instmctions for all types of plant and equipment for each trade group, or as specific task/advice notes for each asset of the service requirements of the plant equipment. When used, the handbook method provides the necessary work instructions for all similar types of plant and equipment throughout the location. This method of operation reduces the number of task/advice notes issued and therefore the system s workload, as well as the demands placed on the administration of the system. Either method eliminates the requirement of entering work instmctions, etc. on the work docket/advice notes before they are issued. 

The principal use of gold is as a very thin coating about 0-05 /xm thick for electrical and electronic applications. Because of the thinness of gold electrodeposits, porosity must be very carefully controlled since seepage of corrosion products from substrate or undercoat exposed at these pores can have serious adverse effects on both appearance and electrical properties of the composite. The porosity can vary with the thickness of the deposit (Fig. 13.1), and with the type of plating bath and with its method of operation (Fig. 13.2), and the phenomenon has been extensively studied by Clarke and many other workers. 

Thomas L. Saaty, Mathematical Methods of Operation Research, McGraw-Hill Book Co, New York, 1959. 

---