Increasing Water Flow

Your cooling tower basin is likely served by a number of circulation supply pumps. You may have observed that putting an additional pump on line does very httle in increasing the combined pump discharge pressure. This means that the total water flow has not increased. For example  

The AP for the three-pump case is 38 psig. The AP for the four-pump case is 40 p sig. That means the pressure drop through the exchangers and piping system has increased by 2 psi, or 5 percent. Since pressure drop varies with flow squared  

The water flow has only increased by 2.5 percent by starting the fourth pump. This does not usually indicate a pump malfunction. More likely, it is an indication that all four pumps are operating on the flat portion of their pump curve, (see Chap. 34, Centrifugal Pumps Fundamentals of Operation. ) To get more water flow, you will need to reduce restrictions in the circulating system. 

I monitored progress by looking at both the process and water effluent temperatures on the hydrotreater cooler. 

I throttled back on the cooling water flow to dozens of exchangers. Several of these water coolers had not been used for years, but no one had bothered to block-in the water flow. Liz and I spent most of an afternoon on this activity. Based on the combined water temperature returning to the cooling tower (see Fig. 32.3), 1 had reduced the total circulating water flow by 20 percent. But the water flow to the hydrotreater effluent cooler had not increased at all. 

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Several technical solutions were considered to Increase the cooling level to the feed section of the screw. Including Increased water flow and the use of chilled water. The best technical solution and quickest to Implement was to Increase the... 

High water flow rates or excessive turbulence are factors that can limit the success of microbial mats. In a field-scale experiment, a 50-cm snowfall flow dramatically increased water flow rates in the mat pond, causing severe damage to the mat. As a result, the pond had to be drained and reinoculated. Snails and other invertebrate herbivores have also been known to damage the mats. 

A further type of PM-located GC is gastrointestinal (GI) C-type GC that is activated by the paracrine peptide hormone guanylin. Guanylin is secreted by GI cells and resultant GC activation and cGMP elevation results in increased Cl transport via the cystic fibrosis transmembrane conductance regulator (CFTR) into the intestinal lumen with resultant increased water flow. The Escherkhia coli heat-stable enterotoxin mimics guanylin in activating this intestinal C-type GC and consequently causes diarrhoea. 

Garwin and Smith (G13) undertook an extensive study of a spray column with benzene dispersed in water, and determined overall heat-transfer coefficients as a function of holdup and phase velocity. Drop size was found to be independent of the water flow rate, and predictable by means of Hayworth and Treybal s equation (H12). However, this may not be true near the flooding point, where relatively few runs were made. The volumetric heat-transfer coefficient increased moderately with increasing water flow rate (except at the high benzene flow rates, where the observed increase was very high) and with benzene flow ratio and holdup. Statistical treatment of their results (T2) yields... 

For the adsorption of micro-organics (p-nitrophenol, benzoic acid) in fixed-bed columns, the half breakthrough time increases proportionally with increasing bed depth but decreases inversely proportionally with increasing water flow rate [54,55]. By studying the adsorption of chloroethylenes on activated carhon fibers, Sakoda et al. [56] determined a linear relationship between the overall mass transfer coefficient (Kfu) and the flow rate Uo. The influence of temperature on file dynamic adsorption of phenol on fibrous activated carbon has also been demonstrated [57]. 

Flow rate—Increased water flow increases oxygen access to the surface and removes protective surface films, so it usually increases corrosion but can sometimes improve access for corrosion-inhibiting reactants. 

Similar results for both inlets were also found in the Tefzel channel and are presented in Fig. 4.6 for the T-junction. Pressure drop increases with increasing water flow rate, similar to the FEP microchannel. This increase is more profound at ionic liquid flow rates higher than 5.65 cm h. ... 

Similarly, a ship with a drift angle to the channel centerline experiences increased water flow past the hull due to the increased blockage factor and a smaller gap... 

The first most commonly encountered problem is swell. The water in the steam drum contains vapour bubbles which expand if the pressure in the drum is reduced, thus increasing the liquid level. So, if there is an increase in steam demand which causes a transient drop in drum pressure, the level controller will reduce the flow of water in order to correct for the apparent increase in level. Of course, on increasing steam demand we need an increased water flow. The pressure in the drum will ultimately be restored, for example by a pressure controller on the steam header increasing the boiler duty, and the level controller will ultimately increase the water flow. However, for the controller to be stable, its initial behaviour means that it will have to act far more slowly than the tight controller defined in Equation (4.14). 

Fig. B.6 Effect of high molecular weight polyethylene oxide) in increasing water flow through fire hoses. Hoses had been adjusted to throw water the same distance and then 30 ppm of polyethylene oxide) were injected into the hose on the left...

Detachment of Particles as a Function of Flow Velocity. A study was also made of the relation between 7p (the adhesion number) and the average water-flow velocity (Fig. VII.4). Naturally, with increasing water-flow velocity the mass of the adhering particles will fall more sharply than the number of particles, since it is easier to remove the larger particles, which carry relative greater masses. 

A round lake of diameter d is fed by a river and drained by seepage. The flow rate of the river is equal to the rate of seepage and thus the water level in the lake is constant. Coincidentally, the level in the lake matches the height of a wide spillway at the north end. Should the water level increase, water flows over the spillway into a flood plain. 

To operate at close to the optimum water flow rate, the operator slowly increases the amount of water just to the point where visible dust emissions abate. Due to the initial sharp increase of dust control effectiveness, the visible dust abatement point is easy to identify. Increasing water flow beyond this point does not yield any significant improvements in dust control, but will most likely cause increased bit degradation and possible seizing of the drill stem. 

The greater driving force then increases water flow through the aquarium s filter. 

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