Tower Testing

Knowledgeable cooling tower users specify the cold water temperature necessary and then thermally test their towers. Cooling towers can be tested accurately at a cost of 1,450 to 2,100 per test. This is a nominal expense compared to the cost of accepting a cooling tower that might be 1°F off in the approach to the wet bulb. Table 3-5 shows that the difference between a tower specified for 87° F as compared to 88° F cold water, is 41,600. 

There are two recognized codes for thermal testing of cooling towers Atmospheric Water- 

Cooling Equipment Power Test Code PTC 23-1958 from The American Society of Mechanical Engineers and Acceptance Test Procedures for Industrial Water-Cooling Tower ATP-105 from The Cooling Tower Institute. 

The two codes are in close agreement except for one important point — wet bulb measurement. The ASME code calls for an ambient wet bulb measurement as follows  

The average wet bulb and dry bulb temperatures shall be determined as an arithmetic average of measurements taken at not less than three locations approximately 5 feet above the basin curb elevation, not less than 50 feet or more than 100 feet to windward of the equipment, and equally spread along a line substantially bracketing the flow of the air to the equipment. 

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Equation 6.8 was obtained from mechanical-draft tower testing. The equation is shown to correlate the data in Figure 6.11. 

Factorial Test Results. Full or partial factorial tests have been conducted at Shawnee, primarily to investigate the effects of adipic acid concentration and pH on SO2 removal. These tests usually lasted 12 hours or longer, including at least 5 to 7 hours of steady-state operation. Scrubber configurations used were venturi alone, spray tower alone, combined venturi and spray tower, and TCA. Limestone was used in all scrubber configurations. Lime was used only with the venturi alone. Only the typical results from the TCA and spray tower tests are presented below to show the degree of effect of pH and adipic acid concentration on SO2 removal. 

Straub, F.K. Kennedy, D.K. Stemple, A.D. Anand, V.R. Birchette, T.S. Development and Whirl Tower Test of the SMART Active Flap Rotor. Smart Structures and Materials 2004 Industrial and Commercial Applications of Smart Structures Technologies, Eric H. Anderson (Ed.), Proc. SPIE Vol. 5388... 

The HILL-SCAN 30XX boards can be used in different PCs. Desktop- and tower-PCs as well suited for laboratory uses. For in-field inspections rugged notebooks and portable PCs are advantageous. A typical portable system is shown in Fig. 2 (USPC 3010), used in MUSE (Mobile Ultrasonic Equipment). This portable PC not only contains the boards for ultrasonic testing but also a controller with power supply for stepper motors, so that a manipulator can be connected directly. The MUSE system is enlarged with a water circulation system which enables a local immersion technique" for in-field inspections. A typical result is shown in Fig. 3, which presents a D-scan of a CFRP- component in RTM-techniques. The defect area caused by an impact is clearly indicated. The manipulator is described in [3]. 

Investigators of tower packings normally report kcCi values measured at very low inlet-gas concentrations, so that yBM = 1, and at total pressures close to 100 kPa (1 atm). Thus, the correct rate coefficient For use in packed-tower designs involving the use of the driving force y — y /yBM is obtained by multiplying the reported k co values oy the value of pf employed in the actual test unit (e.g., 100 kPa) and not the total pressure of the system to be designed. 

The best procedure for making plate-efficiency corrections (which obviously can be quite large) is to use experimental-test data from a prototype system that is large enough to be representative of an acliial commercial tower. 

Aside from the lack of an explicitly defined liquid-phase-resistance term, the limitations on the use of Eq. (14-66) are related to the fact that its derivation implicitly assumes that the system is dilute iysM = 1) and that the operating and equilibrium curves are straight lines over the range of tower operation. Also, Eq. (14-66) is strictly vahd only for the temperature and pressure at which the original test was run even though the total pressure pf appears in the denominator. 

Many operating data for carbonate plants are cited by Kohl and Riesenfeld (Gn.s Purification, Gulf, 1985) but not including tower heights. Pilot plant tests, however, are reported on 0.10- and 0.15-m (4- and 6-in) columns packed to depths of 9.14 m (30 ft) of Raschig rings hy Benson et al. (Chem. Eng. Prog., 50, 356 [1954]). 

The example spreadsheet covers a three-day test. Tests over a period of days provide an opportunity to ensure that the tower operated at steady state for a period of time. Three sets of compositions were measured, recorded, normalized, and averaged. The daily compositions can be compared graphically to the averages to show drift. Scatter-diagram graphs, such as those in the reconciliation section, are developed for this analysis. If no drift is identified, the scatter in the measurements with time can give an estimate of the random error (measurement and fluc tuations) in the measurements. 

The above results are based on data obtained for optimized designs and under ideal test conditions. To translate our findings to the real world, one must factor in liquid and vapor maldistribution, which is far more detrimental to the efficiency of packings than trays. In addition. one also must account for poor optimization or restrictive internals, which are far more detrimental to the capacity of trays than packings. We also have cited several other factors that need to be considered when translating the findings of our analysis to real-world towers. ... 

Tests conducted while the tower is upset can be relied upon only as a general indication of a problem. The data should be suspect and care should be used in its use. If at all possible, reduce rates in an attempt to eliminate the problem, then work up to higher rates. 

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. "... 

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