Lifting condensation level

FIGURE 17.11 Lifting condensation level as a function of initial temperature and relative humidity of the air parcel assuming that the air parcel starts initially at the ground at p = 1 atm. 

The temperature at the lifting condensation level can be calculated by solving (17.48) numerically for Tl. Once TL is determined, the height at the LCL, /iLcl can be found simply by... 

Indices have been developed to express the instability of the environment in quantitative terms. An example is the lifted index, the computation of which is illustrated in Fig. 5 for an environment typical of that in which tomadic thunderstorms form. Surface air is lifted dry adiabatically (dashed curve) until it becomes saturated (at the lifted condensation level). Then it is lifted moist adiabatically to the 500-millibar (mbar) pressure level, passing, in this example, the level of free convection, above which the... 

This cycling can be eliminated by mounting the control valve in the condensate pipe, but this creates new problems, because when the load decreases, the process is slow steam has to condense before the condensate level is affected, and when the load increases, the process is fast, because blowing out liquid condensate is fast. With such "nonsymmetrical" process dynamics, control is bound to be poor. A better option is to use lifting traps to prevent condensate accumulation. These pumping traps will make temperature control possible even when the heater is under vacuum, but will not improve the problem of low rangeability, and the possible use of two control valves in parallel can still be necessary. 

It follows that condensate at the outlet side of the steam trap can only be at atmospheric pressure, and if it is to be lifted to a high-level return line, or into a return line... 

To the funnel is added 1 ml of 6.5 M sulfuric acid from a pipet. The acid is allowed to flow into the flask by carefully lifting the stopper the funnel is rinsed with 2 to 3 ml of water (Note 2). The stopper is reinserted and water (Note 2) is added to the funnel up to the 7-ml mark. After adding a few boiling chips, the reaction mixture is distilled at a rate of 5 to 6ml/5min. The distillate is collected in a 75-ml Erlenmeyer flask. When the volume of the residue in the flask approaches 2 to 3 ml, without interrupting the distillation, the stopper of the funnel is lifted to allow the water to flow into the flask until the water level reaches the 2-ml mark on the funnel. The addition of 5 ml of water is repeated until the distillation is complete. When 20 ml of the first distillate is collected (Note 5), any distillate adhering to the condenser is removed by contacting the condenser tip with the Erlenmeyer flask. At the same time, another 50-mi Erlenmeyer flask is placed under the end of the condenser. 

Liquid level in the reflux accumulator is normally far less troublesome than bottom liquid level. With an all-liquid top product, an overflowing accumulator will usually back up liquid into the condenser, flooding some tubes. This will reduce condensation and prevent further rise in liquid level. Often, column pressure will rise and the relief valve may possibly lift. With a vapor product, excessive accumulator... 

On one occasion, the computer received a signal indicating a low oil level in a gearbox. The computer reacted as the requirements specified It sounded an alarm and left everything as it was. By coincidence, a catalyst had just been added to the reactor, but the computer had only started to increase the cooling-water flow to the reflux condenser the flow was therefore kept at a low rate. The reactor overheated, the relief valve lifted, and the content of the reactor was discharged into the atmosphere. 

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