Towers tower instruments

Acceptance Testing Test procedures to determine the water cooling capacity of towers. Instrumentation used and measurement procedures should be those recommended by the Cooling Tower Institute (CTI) in its "Acceptant Text Procedures. "... 

Loss of utilities including electrical power, steam, cooling tower water, instrument air, and nitrogen. 

Eddy correlation measurements require fast-response instrumentation to resolve the turbulent fluctuations that contribute primarily to the vertical flux. These requirements are particularly severe under stable conditions where response times on the order of 0.2 s or less may be required. In practice, it is often possible to use somewhat slower instruments and apply various corrections to the computed fluxes as compensation. The eddy correlation technique has been used in aircraft (Pearson and Steadman 1980 Lenschow et al. 1982) as well as with tower-mounted instruments. 

Critical temperatures throughout the tower are controlled by automatic instruments and products are withdrawn under various combinations of flow and level control. A pipe still is capable of mnning for days on end with only minor adjustment by the operators except, of course, when a change in crude type or in product distribution is required. 

The notch or weir, in which the fluid flows over the weir so that its kinetic energy is measured by determining the head of the fluid flowing above the weir. This instrument is used in open-channel flow and extensively in tray towers 3 where the height of the weir is adjusted to provide the necessary liquid depth for a given flow. 

The pressure of the atmosphere can be measured with a barometer, an instrument invented in the seventeenth century by Evangelista Torricelli, a student of Galileo. Torricelli (whose name coincidentally means little tower in Italian) formed a little tower of liquid mercury. He sealed a long glass tube at one end, filled it with mercury, and inverted it into a beaker (Fig. 4.4). The column of mercury fell until the pressure that it exerted at its base matched the pressure exerted by the atmosphere. To interpret measurements with a barometer, we need to find how the height of the column of mercury depends on the atmospheric pressure. 

Cooling water (cooling towers) Chilled water Demineralised water Steam (from direct fired boilers) Compressed air (9 bar) Instrument air (9 bar) (dry) Refrigeration Nitrogen... 

Packed columns, 10 769-772, 773 band broadening, 6 412 for distillzation, 5 768-776 gas chromatography, 6 377, 379 instrumentation, 6 423-424 Packed column supercritical fluid chromatography (pSFC), 19 567 Packed fiber-bed mist eliminators, 23 781 Packed towers, 25 810, 811 Packing(s)... 

Implementing this level of automation intelligence has been the most difficult to realize within manufacturing industries. That is, while automation controls integration of simple univariate instruments (e.g., a hlter photometer) is seamless, it is much more problematic for multivariate or spectral instruments. This is due to the tower of babble problem with various process spectroscopic instraments across process instrument manufactures. That is, the communications protocols, wavelength units and hie formats are far from standardized across spectral instruments, even within a particular class of techniques such as vibrational spectroscopy. Several information technology (IT) and automation companies have recently attempted to develop commercialized solutions to address this complex problem, but the effectiveness of these solutions has yet to be determined and reported. 

Improved control devices now frequently installed on conventional coal-utility boilers drastically affect the quantity, chemical composition, and physical characteristics of fine-particles emitted to the atmosphere from these sources. We recently sampled fly-ash aerosols upstream and downstream from a modern lime-slurry, spray-tower system installed on a 430-Mw(e) coal utility boiler. Particulate samples were collected in situ on membrane filters and in University of Washington MKIII and MKV cascade impactors. The MKV impactor, operated at reduced pressure and with a cyclone preseparator, provided 13 discrete particle-size fractions with median diameters ranging from 0,07 to 20 pm with up to 6 of the fractions in the highly respirable submicron particle range. The concentrations of up to 35 elements and estimates of the size distributions of particles in each of the fly-ash fractions were determined by instrumental neutron activation analysis and by electron microscopy, respectively. Mechanisms of fine-particle formation and chemical enrichment in the flue-gas desulfurization system are discussed. 

This vessel can remove 100% of all particles larger than about 2 microns and 99% of those down to about 0.5 micron. Filter separators are commonly used on compressor inlets in field compressor stations, as final scrubbers upstream of gylcol contact towers and in instrument. fuel gas applications. Design is proprietary and dependent upon type of filter element employed. 

A fast chemical sensor that operates at a reduced pressure of 50 torr (6700 Pa) and with a flow of 1 standard liter per minute must be maintained in an instrument shelter. Considerations of flow distortion require that 10 m separate the sensor from its intake on the tower near the sonic anemometer. Three ducting arrangements can be considered. The first would involve drawing air along 10 m of 1/4-inch tubing (0.2 cm internal radius) and controlling the flow and pressure at the sensor itself. The second option would place the pressure-flow controller at the inlet and allow the inlet intake to flow at the reduced pressure. The third course would be to use a... 

Figure 2. Three possible options for ducting atmospheric air from the inlet on the tower to the sensor in the instrument shelter.

The instruments usually provided for cooling towers and circulating pumps include ... 

Float valves are required on all cooling tower systems. Their purpose is to supply makeup water to replace that lost by evaporation, blowdown, drift and system leakage. They are usually installed in the cold water basin and function to maintain a preestablished water level. A typical flowsheet showing the recommended arrangements for instrumentation and valves is given in Figure 7.4. 

The specifier must have a good understanding of instrumentation and support machinery. Any process instrumentation book will acquaint the newcomer to this area with the criteria for proper instrumentation selection. To illustrate the process involved in specifying the entire cooling tower system package, the following example has been prepared. 

The cooling tower manufacturer shall conduct the acceptance performance test and shall supply the necessary instruments to conduct the test in accordance with the requirements of the CTI Test Procedure ATP-105, latest revision. 

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