Plant size, control

Favorable operational economics and good management practices require high levels of control of the ozonation system. Depending on the specific process of ozone applications, plant size, and design philosophy, the control system may be simple or complex. The trend in Europe is toward highly sophisticated and centralized control. 

Whether the boiler is fired on oil, gas or solid fuel, it may be expected that it will operate automatically. When boiler plant is not run continuously initial start-up may be manual, time clock or through an energy-management system. Manual attendance may be limited to maintenance functions dictated by the type and size of plant. Automatic controls will cover three areas ... 

In the polymer industry, post-reaction product treatment processes such as liquid-solid separation, drying, precipitation, particle size control, and polymer purification are very complex and costly. Future polymer plants should be designed such that process equipment can be easily and quickly converted to making new products at minimal cost and with... 

Our Chemical Engineering colleagues had developed an elegant impinging jet crystallization which provided excellent particle size control for the finasteride process [13]. In the final pilot plant campaign just before the factory start-up, the crystallization suddenly started producing a different particle size distribution and lower recovery. The problem was traced to a new finasteride solvate which reduced the solubility in the crystallization solvent system. Fortunately, only relatively... 

One of the classical problems in scaling-up a jacketed reactor is the decrease in the ratio of heat-transfer area to reactor volume as size is increased. This has a profound effect on the controllability of the system. Table 11.1 gives some results that quantify the effects for reactors varying from 5 gallons (typical pilot-plant size) to 5CKX) gallons. Table 11.2 gives parameter values that are held constant as the reactor is scaled up. 

Modularity. Economic competitiveness requires that the construction time be shortened dramatically. Modular construction techniques arc a key contiibntoi to achieving this goal and are a proven approach to cost control in major construction projects. Modularization provides for a larger percentage of factory construction, rather than field construction. New innovative concepts will rely heavily on modularization and will be centered around lower unit power outputs, factory assembly, and transportation of modules to the plant site. The overall plant size target is 600 MWe net electrical output. 

Particle size control The plant pictured produces a multimodal size distribution, consisting... 

In designing pulse combustor/atomizer drying systems, the pulse intensity as well as the temperature and velocity of the gas at the point of atomization are optimized for each product. A particular advantage of the technology is, that the plant s control system can modify the process conditions such that a variety of dry powder characteristics are met without physically changing the equipment. These characteristics primarily include particle size, flowability, texture, temperature history, residual moisture content, flavor, and ease of reconstitution. 

What happens quantitatively on a larger scale is answered in experiments which tend to produce solutions for the physical problems. Usually they involve the trial of one catalyst recipe and a few reactor types giving the optimum space-time yields of desired product together with auxiliary heat transfer and pressure-drop data. The catalyst abrogate is preferably of the probable plant size, produced under conditions of quality control in the laboratory or the plant. 

Diffusion coefficients are typically higher in SCFs than in liquids. This is partly because the substances used as the solvent, such as carbon dioxide, have typically lighter and smaller molecules than organic liquid solvents and partly because the density of an SCF is typically less than a liquid. Consequently, reactions controlled by diffusion may be faster than in a liquid, giving the advantage of smaller process plant size. However, in the region of the critical point, diffusion coefficients can show an anomalous lowering, which can effect reaction rates. The behavior of diffusion coefficients is therefore discussed in Section 1.3.1 and its effect on reactions in Section 1.3.2. 

Most of the literature of pyrotechnics available in English is unenlightening on the subject of charcoal. Most of the commercial producers of charcoals in the United States have no appreciation for the needs of pyrotechnists. The commercial producers seem to feel that if it is black and about the proper mesh size then it is suitable for pyrotechnics. In the author s experience no two species of wood or other plants produce charcoal with identical properties. Many pyrotechnists seem to think that particle size controls the reactivity of the charcoal. They have only to examine a fast burning composition from the Orient to realize this is not always the case. Gross particle size does have a marked effect on the reactivity, but not to the same degree that species factors and charring conditions do. 

Regarding the module development, the module size continues to become larger along with the increase of the plant size, and currently, there seems no limit for this trend. As the module size increases, so also do the sizes of pumps, pipes, etc., and more precise system control will be required. 

TSCA provides specific guidance and requirements for data gathering and reporting. This includes information such as production volume, plant size, amount lost to the environment during production or import, quantity of releases, and worker exposure information pertaining to controlled or uncontrolled releases. Companies are also required to maintain records of allegations of signifieant health or environmental effects (Section 8). 

Hoffmeister, G. H. 1982. Particle Size Require-merits for Bulk Blend Materials, TVA Circular Z-146, Paper presented at the 36th annual meeting of the Association of American Plant Food Control Officials, August 3-4, Columbus, OH, U.S.A. 

---