C02 emissions

When used to separate solid-solid mixtures, the material is ground to a particle size small enough to liberate particles of the chemical species to be recovered. The mixture of solid particles is then dispersed in the flotation medium, which is usually water. Gas bubbles become attached to the solid particles, thereby allowing them to float to the surface of the liquid. The solid partices are collected from the surface by an overflow weir or mechanical scraper. The separation of the solid particles depends on the different species having different surface properties such that one species is preferentially attached to the bubbles. A number of chemicals are added to the flotation medium to meet the various requirements of the flotation process  [c.70]

All that can be done is to make a reasonable initial assessment of the number of stages. Having made a decision for the number of stages, the heat flow through the system is temporarily fixed so that the design can proceed. Generally, the maximum temperature in evaporators is set by product decomposition and fouling. Therefore, the highest-pressure stage is operated at a pressure low enough to be below this maximum temperature. The pressure of the lowest-pressure stage is normally chosen to allow heat rejection to cooling water or air cooling. If decomposition and fouling are not a problem, then the stage pressures should be chosen such that the highest-pressure stage is below steam temperature and the lowest-pressure stage above cooling water or air cooling temperature.  [c.87]

Now cascade any surplus heat down the temperature scale from interval to interval. This is possible because any excess heat available from the hot streams in an interval is hot enough to supply a deficit in the cold streams in the next interval down. Figure 6.18 shows the cascade for the problem. First, assume that no heat is supplied to the first interval from a hot utility (Fig. 6.18a). The first interval has a surplus of 1.5 MW, which is cascaded to the next interval. This second interval has a deficit of 6 MW, which reduces the heat cascaded from this interval to -4.5 MW. In the third interval the process has a surplus of 1 MW, which leaves -3.5 MW to be cascaded to the next interval, and so on.  [c.178]

Overall, the accuracy of the capital cost targets is more than good enough for the purposes for which they are used  [c.233]

Flash point. The flash point of a liquid is the lowest temperature at which it gives off enough vapor to form an ignitable mixture with air. The flash point generally increases with increasing pressure.  [c.256]

Reactors. Perhaps the worst safety problem that can occur with reactors occurs when an exothermic reaction generates heat at a faster rate than the cooling can remove it. Such runaway reactions are usually caused by coolant failure, perhaps for a temporary period, or reduced cooling capacity due to perhaps a pump failure in the cooling water circuit. The runaway happens because the rate of reaction, and hence the rate of heat generation, increases exponentially with temperature, whereas the rate of cooling increases only linearly with temperature. Once heat generation exceeds available cooling capacity, the rate of temperature rise becomes progressively faster." If the energy release is large enough, liquids will vaporize, and overpressurization of the reactor follows.  [c.262]

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]

In this accident, the steam was isolated from the reactor containing the unfinished batch and the agitator was switched ofiF. The steam used to heat the reactor was the exhaust from a steam turbine at 190 C but which rose to about 300°C when the plant was shutdown. The reactor walls below the liquid level fell to the same temperature as the liquid, around 160°C. The reactor walls above the liquid level remained hotter because of the high-temperature steam at shutdown (but now isolated). Heat then passed by conduction and radiation from the walls to the top layer of the stagnant liquid, which became hot enough for a runaway reaction to start (see Fig. 9.3). Once started in the upper layer, the reaction then propagated throughout the reactor. If the steam had been cooler, say, 180 C, the runaway could not have occurred.  [c.264]

Relief systems are expensive and introduce considerable environmental problems. Sometimes it is possibly to dispense with relief valves and all that comes after them by using stronger vessels, strong enough to withstand the highest pressures that can be reached. For example, if the vessel can withstand the pump delivery pressure, then a relief valve for overpressurization by the pump may not be needed. However, there may still be a need for a small relief device to guard against overpressurization in the event of a fire. It may be possible to avoid the need for a relief valve on a distillation column  [c.265]

At first sight, it might seem that making vessels strong enough to withstand the possible overpressurization would be an expensive option. However, we must not lose sight of the fact that we are not simply comparing one vessel with a thick wall versus one vessel with a thin wall protected by a relief valve. Material discharged through the relief valve might need to be partially contained, in which case the comparison might be between Fig. 9.4a and ft.  [c.266]

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]

Install enough intermediate storage to allow reworking of off-specification material.  [c.290]

Knowing where waste is going is the key to reducing it. When reducing waste from process operations, a steady-state mass balance is not usually comprehensive enough. A balance that takes into account start-up, shutdown, and product changeovers is required.  [c.296]

Allowing enough intermediate storage to rework ofT-specification material.  [c.297]

Evaporation processes usually separate a single component (typically water) from a nonvolatile material. As such, it is good enough in most cases to assume that the vaporization and condensation processes take place at constant temperatures.  [c.355]

Very high temperature and pressure on graphite in the presence of a metal catalyst gives synthetic diamonds big enough for many industrial uses.  [c.132]

It is common that a mixture of hydrocarbons whose boiling points are far enough apart petroleum cut) is characterized by a distillation curve and an average standard specific gravity. It is then necessary to calculate the standard specific gravity of each fraction composing the cut by using the relation below [4.8]  [c.94]

Holland, C. D., Gallun, S. E. and Lockett, M. J., Modeling Azeotropic and Extractive Distillations, Chem. Engg., 88 185, March 23, 1981.  [c.93]

Porter, K. E., and Momoh, S. O., Finding the Optimum Sequence of Distillation Columns—An Equation to Replace the Rules of Thumb (Heuristics), Chem. Engg. J., 46 97, 1991.  [c.157]

Gas turbine integration. Figure 6.34 shows a simple gas turbine matched against a process. The machine is essentially a rotary compressor mounted on the same shaft as a turbine. Air enters the compressor, where it is compressed before entering a combustion chamber. Here the combustion of fuel increases its temperature. The mixture of air and combustion gases is expanded in the turbine. The input of energy to the combustion chamber allows enough shaftwork to be developed in the turbine to both drive the compressor and provide useful work. The expanded gas may be discharged to the atmosphere directly or may first be used to preheat the air to the  [c.196]

FIgura 7.1 Two alternative graphs. (Reprinted from Linnhoff, Mason, and Wardle, Understanding Heat Exchan r Networks Computers Ckem. Engg., 3 295, 1979 with permission from Elsevier Science, Ltd.)  [c.214]

FIgur 7.4 If film transfer coefficients difier significantly, then nonvertical h t transfer is necessary to achieve the minimum area. (Reprinted from Linnhoff and Ahmad, Cost Optimum Heat Exchanger Networks I. Minimum Energy and Capital Using Simple Models for Capital Cost," Computers Chem. Engg., 7 729, 1990 with permission from Elsevier Science, Ltd.)  [c.218]

Figure 7.9 The Xp parameter avoids steep slopes on the Fp curves, whereas minimum Fp does not. (Reprinted from Ahmad, Linnhoff, and Smith, Cost Optimum Heat Exchanger Networks II. Targets and Design for Detailed Capital Cost Models, Computers Chem, Engg., 7 751, 1990 with permission from Elsevier Science, Ltd.) Figure 7.9 The Xp parameter avoids steep slopes on the Fp curves, whereas minimum Fp does not. (Reprinted from Ahmad, Linnhoff, and Smith, Cost Optimum Heat Exchanger Networks II. Targets and Design for Detailed Capital Cost Models, Computers Chem, Engg., 7 751, 1990 with permission from Elsevier Science, Ltd.)
Figure 10.5 The direct chlorination step of the vinyl chloride process using a liquid phase reactor. (From McNaughton, Chem. Engg., December 12, 1983, pp. 54-58 reproduced by permission.) Figure 10.5 The direct chlorination step of the vinyl chloride process using a liquid phase reactor. (From McNaughton, Chem. Engg., December 12, 1983, pp. 54-58 reproduced by permission.)
Rgure 10.6 The direct chlorination step of the vinyl chloride process using a boiling reactor eliminates the washing and neutralization steps and the resulting effluents. (From McNaughton, Chem. Engg., December 12, 1983, pp. 54-58 reproduced by permission.)  [c.286]

McNaughton, K. J., Ethylene Dichloride Process, Chem. Engg., 12 54, 1983.  [c.298]

It is not only the stream number that creates the need to split streams at the pinch. Sometimes the CP inequality criteria [Eqs. (16.1) and (16.2)] CEmnot be met at the pinch without a stream split. Consider the above-pinch part of a problem in Fig. 16.13a. The number of hot streams is less than the number of cold, and hence Eq. (16.3) is satisfied. However, the CP inequality also must be satisfied, i.e., Eq. (16.1). Neither of the two cold streams has a large enough CP. The hot stream can be made smaller by splitting it into two parallel branches (Fig. 16.136).  [c.376]

Lang, H. J., Cost Relationships in Preliminary Cost Estimation, Chem. Engg., 54 117, 1947.  [c.426]

Guthrie, K. M., Data and Techniques for Preliminary Capital Cost Estimating, Chem. Engg., 76 114, 1969.  [c.426]

Hall, R. S., Matley, J., and McNaughton, K. J., Current Costs of Process Equipment, Chem. Engg., 89 80, 1982.  [c.426]

HaU, R. S., Vatavuk, W. M., and Matley, J., Estimating Process Equipment Costs, Chem. Engg., 95 66, 1988.  [c.426]

Remer, D. S., and Chai, L. H., Design Cost Factors for Scaling-up Engineering Equipment, Chem. Engg. Progr., 86 Aug. 77, 1990.  [c.426]

Bauman, H. C., Estimating Cost of Process Auxiliaries, Chem. Engg. Progr., 51 45, 1955.  [c.426]

MarkownikofT s rule The rule states that in the addition of hydrogen halides to an ethyl-enic double bond, the halogen attaches itself to the carbon atom united to the smaller number of hydrogen atoms. The rule may generally be relied on to predict the major product of such an addition and may be easily understood by considering the relative stabilities of the alternative carbenium ions produced by protonation of the alkene in some cases some of the alternative compound is formed. The rule usually breaks down for hydrogen bromide addition reactions if traces of peroxides are present (anti-MarkownikofT addition).  [c.251]

The need for this detector arose when gasolines containing oxygenates such as alcohols, and especially ethers, were introduced for which composition and content were subject to regulations. Following separation in a chromatographic column, the molecules pass through a dracker where the hydrocarbons are retained and where the molecules containing oxygen give CO. This gas is then sent to a methanizer where it is converted to CH and detected thence by an FID. When well adjusted, the type of detector is very selective and sensitive enough to measure oxygen contents as low as a few dozen ppm.  [c.79]

See pages that mention the term C02 emissions : [c.69]    [c.88]    [c.93]    [c.157]    [c.266]    [c.298]    [c.377]    [c.383]    [c.82]    [c.140]    [c.163]    [c.221]    [c.247]    [c.306]    [c.310]    [c.351]   
Chemical process design (2000) -- [ c.305 ]