Processes process improvement

Rules of Thumb about the Thinking Process Process Improvement... 

Liquid products must undergo hydrogen processing before joining equivalent crude oil fractions and continuing the normal process property improvement steps. 

Successive PCA and Wavelet analysis processes improve small flaw detection (figure 14), because small size involves linear physical processes, where PCA is efficient. 

For the sake of illustration, a TOF analyzer could be likened to a camera taking snapshots of the m/z values of an assembly (beam) of ions the faster the repetition rate at which the camera shutter is clicked, the greater is the number of mass spectra that can be taken in a very short time. For TOF analyzers, it is not uncommon to measure several thousand mass spectra in one second All such spectra can be added to each other digitally, a process that improves the signal-to-noise ratio in the final accumulated total. 

With the maturing of the propylene oxidation catalyst area, attention in the 1980s was more focused on reaction process related improvements. 

The catalytic vapor-phase oxidation of propylene is generally carried out in a fixed-bed multitube reactor at near atmospheric pressures and elevated temperatures (ca 350°C) molten salt is used for temperature control. Air is commonly used as the oxygen source and steam is added to suppress the formation of flammable gas mixtures. Operation can be single pass or a recycle stream may be employed. Recent interest has focused on improving process efficiency and minimizing process wastes by defining process improvements that use recycle of process gas streams and/or use of new reaction diluents (20-24). 

Recent patents and pubHcations describe process improvements. Conversions can be followed by on-line hplc (93). The enzyme amidase can be used to reduce residual monomers (94—96). A hydrogenation process for reduction of acrylamide in emulsions containing more that 5% residual monomer has been patented (95). Biodegradable oils have been developed (97). 

Elimination of unreacted monomers can be accompHshed by two methods dual initiators to enhance conversion of monomers to product (73—75) and steam stripping (70,76). Several process improvements have been claimed for dewatering beads (77), to reduce ha2e (78—81), improve color (82—86), remove monomer (87,88), and maintain homogeneous copolymer compositions (71,72,89). 

High Tena.city Sta.ple Fibers. When stronger staple fibers became marketable, the tire yam processes were adapted to suit the high productivity staple fiber processes. Improved staple fibers use a variant of the mixed modifier approach to reach 0.26 N /tex (3 gf/den). The full 0.4 N /tex (4.5 gf/den) potential of the chemistry is uimecessary for the target end uses and difficult to achieve on the regular staple production systems. 

An analytical model of the process has been developed to expedite process improvements and to aid in scaling the reactor to larger capacities. The theoretical results compare favorably with the experimental data, thereby lending vahdity to the appHcation of the model to predicting directions for process improvement. The model can predict temperature and compositional changes within the reactor as functions of time, power, coal feed, gas flows, and reaction kinetics. It therefore can be used to project optimum residence time, reactor si2e, power level, gas and soHd flow rates, and the nature, composition, and position of the reactor quench stream. 

The economics of the arc-coal process is sensitive to the electric power consumed to produce a kilogram of acetylene. Early plant economic assessments indicated that the arc power consumption (SER = kwh/kgC2H2) must be below 13.2. The coal feedcoal quench experiments yielded a 9.0 SER with data that indicated a further reduction to below 6.0 with certain process improvements. In the propane quench experiment, ethylene as well as acetylene is produced. The combined process SER was 6.2 with a C2H2/C2H4 production ratio of 3 to 2. Economic analysis was completed uti1i2ing the achieved acetylene yields, and an acetylene price approximately 35% lower than the price of ethylene was projected. 

Uses. A soluble form of magnesium nitrate is used as a fertilizer ia states such as Florida where drainage through the porous, sandy soil depletes the magnesium (see Fertilizers). Magnesium nitrate is also used as a prilling aid in the manufacture of ammonium nitrate. A 0.25—0.50% addition of magnesium nitrate to the process improves the stabHity of the prills and also improves durabHity and abrasion resistance. 

Zinc. The electrowinning of zinc on a commercial scale started in 1915. Most newer faciUties are electrolytic plants. The success of the process results from the abiUty to handle complex ores and to produce, after purification of the electrolyte, high purity zinc cathodes at an acceptable cost. Over the years, there have been only minor changes in the chemistry of the process to improve zinc recovery and solution purification. Improvements have been made in the areas of process instmmentation and control, automation, and prevention of water pollution. 

Metal Treatment. After rolling, the oxide scale on sheet steel is removed by acid treatment (pickling) (see Metal surface treatments). Phosphoric acid, a good pickling agent, leaves the steel coated with a thin film of iron phosphates. This process improves mst resistance but presents a problem if the steel is to be electroplated. 

Chemical Sensitization. After the photographic microcrystals are precipitated but before they are coated on a support, the crystals are treated to enhance their sensitivity to light. Chemical sensitization is a process which improves that abiUty of the emulsion grains to use the absorbed photons, independent of the wavelength. Various methods of post-precipitation chemical sensitization have been developed to reduce the number of photons required to produce a developable latent-image center. 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

The polymer is exposed to an extensive heat history in this process. Early work on transesterification technology was troubled by thermal—oxidative limitations of the polymer, especially in the presence of the catalyst. More recent work on catalyst systems, more reactive carbonates, and modified processes have improved the process to the point where color and decomposition can be suppressed. One of the key requirements for the transesterification process is the use of clean starting materials. Methods for purification of both BPA and diphenyl carbonate have been developed. 

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