Computer control success

Memfield successfully automated all the steps m solid phase peptide synthesis and computer controlled equipment is now commercially available to perform this synthesis Using an early version of his peptide synthesizer m collaboration with coworker Bemd Gutte Memfield reported the synthesis of the enzyme ribonuclease m 1969 It took them only SIX weeks to perform the 369 reactions and 11 391 steps necessary to assemble the sequence of 124 ammo acids of ribonuclease... 

The Aromax process was developed in the early 1970s by Toray Industries, Inc. in Japan (95—98). The adsorption column consists of a horizontal series of independent chambers containing fixed beds of adsorbent. Instead of a rotary valve, a sequence of specially designed on—off valves under computer control is used to move inlet and withdrawal ports around the bed. Adsorption is carried out in the Hquid phase at 140°C, 785—980 kPA, and 5—13 L/h. PX yields per pass is reported to exceed 90% with a typical purity of 99.5%. The first Aromax unit was installed at Toray s Kawasaki plant in March 1973. In 1994, IFP introduced the Eluxyl adsorption process (59,99). The proprietary adsorbent used is designated SPX 3000. Individual on-off valves controlled by a microprocessor are used. Raman spectroscopy to used to measure concentration profiles in the column. A 10,000 t/yr demonstration plant was started and successfully operated at Chevron s Pascagoula plant from 1995—96. IFP has Hcensed two hybrid units. 

Computer Control. The use of computer systems to control the operation of submerged arc furnaces, including calcium carbide, has been successfully demonstrated in the United States (see Expert systems Process control). Operations direcdy under control are mix batching, electrode position and sHp control, carbide gas yield, power control, and cooling water systems. Improvements in energy usage, operating time, and product quaHty are obtained. 

Considerable success has been achieved in controlling the MWD of the products of polymerization where the life-times of propagating centres are long. These studies and others using computer controlled reactors will be reported elsewhere. 

Hollow-cathode lamps are currently available for over sixty elements. Several multi-element lamps have been constructed and are useful for routine determinations, but they have proved to be of doubtful performance up to now. More successful with regard to multi-element analysis have been computer controlled automated systems, which enable a programme of sequential measurements to be made with instrumental parameters being adjusted to the optimum for each element to be measured. 

Two types of nonlinear optimizers—the sectionalized linear program and the gradient search—have been successfully implemented in advanced computer control schemes. 

The above features make the Smith-Brinkley method valuable for on-line optimization (e.g., using microprocessor or computer control). It can be beneficial for assessing the effects of perturbations on column performance and driving the control point toward an optimum. It is also valuable for off-line optimization and for revamp studies. Rice (58a) extended the Smith-Brinkley method to yield individual stage temperatures and compositions and successfully applied it for control. 

Labour, Maintenance and Administrative Costs. As a general rule, labour and maintenance were each charged at the rate 3% of the capital per annum. For labour, this included both direct and indirect labour costs. For maintenance, this included both materials and labour. Over the past decades, many companies have made attempts to reduce the operating labour and maintenance charges. Labour can be reduced by extensive computer control. However, the success or otherwise, in reducing the maintenance charge is difficult to quantify, several operations have suffered major problems claimed to be due to the cutbacks in maintenance costs. Administrative costs are basically insurance and local land taxes. A value of 1.5% of the fixed capital as an annual charge was used. 

The second method for catalyzing the membranes is to cast the same type of ink (TBA" " form of the ionomer) directly onto the membrane [44]. This process may have an advantage over the decal process in the formation of a more intimate membrane/ electrode interface. It may also be more amenable to scale-up. Indeed, initial attempts at laboratory-scale automated application of thin-film Pt/C//ionomer catalyst layers to ionomeric membranes have been quite successful. In this work, a computer-controlled mechanism of an X-Y recorder was applied to paint catalyst ink by the controlled repetitive motion of the pen of the recorder onto each of the membrane major surfaces. In this way, 100 cm areas of catalyzed membranes were re-producibly generated, yielding performances per cm of a similar level to that achieved previously with catalyzed membrane of 5 cm active area [44]. The laboratory-scale automation equipment is shown in Fig. 22. 

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