Using what appeared to be the most reliable data available, we investigated the propriety of fitting with 2, 4, and 5-parameter forms of Equation (2) as well as the effect of different uncertainty factors a. The two-parameter form is useful only when the data are sparse and scattered. The differences between the four-parameter form and five-parameter form are not large but, in general, the five-parameter form appears to give superior fits and superior values of the derivative, thus giving better agreement with experimental enthalpies for those cases where good data were available.  [c.141]

F Rachford-Rice objective function for liquid-liquid separa-  [c.335]

Spray dryers are shown in Fig. 3.15d. Here, a liquid or slurry  [c.89]

Another important class of dryer is the fluidized-bed dryers. Some designs combine spray and fluidized-bed dryers. Choice between dryers is usually based on practicalities such as the materials handling characteristics, product decomposition, product physical form (e.g., if a porous granular material is required), etc. Also, dryer efficiency can be used to compare the performance of different dryer designs. This is usually defined as follows -.  [c.91]

Flammable liquids are potentially much more dangerous than flammable gas mixtures because of the greater mass which may be present. This is especially true if the liquids are processed or stored under pressure at a temperature above their atmospheric boiling point. Gases leak at a lower mass flow rate than liquids through an opening of a given size. Flashing liquids leak at about the same rate as a subcooled liquid but then turn into a mixture of vapor and spray. The spray, if fine, is just as hazardous as the vapor and can be spread as easily by the wind. Thus the leak of a flashing liquid through a  [c.256]

When synthesizing a flowsheet, it is more important to avoid the occurrence of flammable gas mixtures than to rely on elimination of sources of ignition. This may be achieved in the first instance by changing the process conditions such that mixtures are outside the flammable range. If this is not possible, inert material such as nitrogen, carbon dioxide, or steam should be introduced. The use of flammable liquids held under pressure above their atmospheric boiling points should be avoided. Adopting atmospheric subcooled conditions or vapor conditions in the process will be much safer. In addition, sources of ignition such as flames, electrical equipment, static electricity, etc. also should be eliminated wherever possible.  [c.257]

Reaction rates often may be improved by using more extreme operating conditions. More extreme conditions may reduce inventory appreciably. However, more extreme conditions bring their own problems, as we shall discuss later. A very small reactor operating at a high temperature and pressure may be inherently safer than one operating at less extreme conditions because it contains a much lower inventory. A large reactor operating close to atmospheric temperature and pressure may be safe for different reasons. Leaks are less likely, and if they do happen, the leak will be small because of the low pressure. Also, little vapor is produced from the leaking liquid because of the low temperature. A compromise solution employing moderate pressure and temperature and medium inventory may combine the worst features of the extremes. The compromise solution may be such that the inventory is large enough for a serious explosion or serious toxic release if a leak occurs, the pressure will ensure that the leak is large, and the high temperature results in the evaporation of a large proportion of the leaking liquid.  [c.263]

Distillation. There is a large inventory of boiling liquid, sometimes under pressure, in a distillation column, both in the base and held up in the column. If a sequence of columns is involved, then, as discussed in Chap. 5, the sequence can be chosen to minimize the inventory of hazardous material. If all materials are equally hazardous, then choosing the sequence that tends to minimize the flow rate of nonkey components also will tend to minimize the inventory. Use of the dividing-wall column shown in Fig. 5.17c will reduce considerably the inventory relative to two simple columns. Dividing-wall columns are inherently safer than conventional arrangements because they lower not only the inventory but also the number of items of equipment and hence lower the potential for leaks.  [c.263]

Large quantities of toxic gases such as chlorine and ammonia and flammable gases such as propane and ethylene oxide can be stored either under pressure or at atmospheric pressure under refrigerated conditions. If there is a leak from atmospheric refrigerated storage, the quantity of hazardous material that is discharged will be less than that from a corresponding pressurized storage at atmospheric temperature. For large storage tanks, refrigeration is safer. However, this might not be the case with small-scale storage, since the refrigeration equipment provides sources for leaks. Thus, in small-scale storage, pressurization may be safer.  [c.265]

Similarly, instead of installing vacuum relief valves the vessels can be made strong enough to withstand vacuum. In addition, if the vessel contains flammable gas or vapor, vacuum relief valves will often need to admit nitrogen to avoid flammable mixtures. A stronger vessel often may be safer and cheaper.  [c.266]

Intensification of hazardous materials results in a safer process. In  [c.266]

It is easy to say that operation of a reactor at higher temperature might lead to a safer plant if the inventory can be reduced as a result, but how do we assess such changes quantitatively Lowering the inventory makes the plant safer, but raising the temperature makes it less safe. Which effect is more significant  [c.268]

In fact, the true fire load will be greater than the energy release calculated in Example 9.1. In practice, such a release of superheated liquid generates large amounts of fine spray in addition to the vapor. This can double the energy release based purely on vaporization.  [c.270]

Store in a safer form (less extreme pressure or temperature or in a difierent chemical form).  [c.272]

When synthesizing a flowsheet, the designer should consider carefully the problems associated with operation under extreme conditions. Attenuation will result in a safer plant, providing the attenuation does not increase the inventory of hazardous materials.  [c.272]

What you don t have, can t leak. If we could design our plants so that they use safer raw materials and intermediates, or not so much of the hazardous ones, or use the hazardous ones at lower temperatures and pressures or diluted with inert materials, then many problems later in the design could be avoided.  [c.272]

Kletz, T. A., Cheaper, Safer Plants, IChemE Hazard Workshop, 2d., IChemE, Rugby, U.K., 1984.  [c.272]

Radial water spray  [c.303]

Unfortunately, the overall design problem is even more complex in practice. Spare driving forces in the process could be exploited equally well to allow the use of moderate utilities or the integration of heat engines, heat pumps, etc. in preference to distillation integration.  [c.353]

Thus steam systems typified by the one in Fig. A.l exhibit many complex interactions. It is extremely difiicult to say exactly what the cost of any of the steam levels is. The only truly reliable way to determine the economic benefit of saving, say, low-pressure steam is to simulate the effect of that saving on the steam system and cost the change. Although this low-pressure steam saving will bring a fuel saving and water treatment saving (and hence cost saving), it will lead to lower power generation, and any shortfall in power will need to be generated by the condensing turbine (if there is one and it has spare capacity) or imported from centralized power generation (giving a cost penalty). Thus these various changes can be costed to evaluate the true economic benefit from the low-pressure saving.  [c.413]

Aerosol sprays consist of a material dissolved or suspended in a liquid which when pressure is released volatilizes to produce a fine spray. The spray carries the active material. Used in hair lacquers, paints, etc. the propellant should be inert and non-inflammable. Chlorofluorocarbons have been used extensively but are now being replaced.  [c.17]

Fischer-Speier esterification method The  [c.175]

Predictions for the other isobaric systems (experimental data of Sinor, Steinhauser, and Nagata) show good agreement. Excellent agreement is obtained for the system carbon tetrachlor-ide-methanol-benzene, where the binary data are of superior quality.  [c.55]

Equation (7-8). However, for liquid-liquid equilibria, the equilibrium ratios are strong functions of both phase compositions. The system is thus far more difficult to solve than the superficially similar system of equations for the isothermal vapor-liquid flash. In fact, some of the arguments leading to the selection of the Rachford-Rice form for Equation (7-17) do not apply strictly in the case of two liquid phases. Nevertheless, this form does avoid spurious roots at a = 0 or 1 and has been shown, by extensive experience, to be marltedly superior to alternatives.  [c.115]

When synthesizing a fiowsheet, the designer should consider carefully the problems associated with operation under extreme conditions. Attenuation will result in a safer plant, providing the attenuation does not increase the inventory of hazardous materials. If the inventory does not increase, then attenuation not only will make the process safer but also will make it cheaper, since cheaper materials of construction and thinner vessel walls can be used and it is not necessary to add on so much protective equipment.  [c.268]

In addition, the decrease in driving forces in Fig. 12.1 caused by the process changes also affects the potential for using multiple utilities. For example, as the driving forces above the pinch become smaller, the potential to switch duty from high-pressure to low-pressure steam, as discussed in Sec. 6.6, decreases. Process changes are competing with better choices of utility levels, heat engines, and heat pumps for available spare driving forces. Each time either a process change or a different choice of utilities is suggested, the capital/energy tradeoff should be readjusted. If multiple utilities are used, the optimization of the capital/energy tradeoff is not straightforward, since each pinch (process and utility) can have its own value of ATnim- The optimization thus becomes multidimensional.  [c.323]

SbBr (Br2 plus Sb) m.p. 97"C, b.p. 280"C, similar to SbC. Higher bromides are not known although complexes, M2SbBre, (contains Sb(rri) and Sb(V)) and MShBr are known.  [c.38]

Antimonypentafluoride, SbFj, m.p. 7 C, b.p. 150 C is an associated liquid (Sb plus F2 or SbClj plus HF). Forms many complexes and complex ions including [ShF ]", [Sb2Fu]" and is a very powerful fluoride ion acceptor. Greatly enhances the dissociation of, e.g. HF and HSO3F by forming anionic species (magic acid, super acid). Used as a fluorinating agent (sometimes in the form of its graphite intercalation compound).  [c.39]

See pages that mention the term Sprues : [c.296]    [c.90]    [c.91]    [c.311]    [c.396]    [c.52]    [c.52]    [c.75]    [c.76]    [c.95]    [c.147]    [c.163]    [c.167]    [c.179]    [c.201]    [c.217]    [c.263]    [c.275]    [c.291]    [c.297]    [c.322]    [c.355]   
Plastics engineering Изд.3 (2002) -- [ c.288 ]