Sumps

Sand production from loosely consolidated formations may lead to erosion of tubulars and valves and sand-fill in of both the sump of the A/ell and surface separators. In addition, sand may bridge off in the tubing, severely restricting flow. The presence of sand production may be monitored by in-line detectors. If the quantities of sand produced become unacceptable then downhole sand exclusion should be considered (Section 9.7). 

A static leaf filter is used for cleaning machine tool coolants. These are used on the suction side of a pump circulating system, with the same pump employed for withdrawal of the filtrate as for backdushing the filter elements. SoHds in this case are removed from the sump by a scraper conveyor. 

Polyol ester turbine oils currendy achieve greater than 10,000 hours of no-drain service in commercial jet aircraft with sump temperatures ranging to over 185°C. Polyol esters are made by reacting a polyhydric alcohol such as neopentyl glycol, trimethylol propane, or pentaerythritol with a monobasic acid. The prominent esters for automotive appfications are diesters of adipic and a2elaic acids, and polyol esters of trimethylolpropane and pentaerythritol (34). 

Fig. 2. The Dow magnesium cell. The steel container. A, is equipped with a ceramic cover, B, through which graphite anodes, C, pass. The magnesium is deposited on the cathode, D, and is diverted as it rises into the collection sump, E. The chlorine is withdrawn through a vent, F.

N2, and traces of PH, CO2, E, and S large furnaces generate off-gas at a rate of about 120—180 m /min. In most installations the off-gas is passed through a series of Cottrell electrostatic precipitators which remove 80—95% of the dust particles. The precipitators ate operated at temperatures above the 180°C dew point of the phosphoms. The collected dust is either handled as a water slurry or treated dry. Einal disposal is to a landfill or the dust is partially recycled back to the process. The phosphoms is typically condensed in closed spray towers that maintain spray water temperatures between 20 and 60°C. The condensed product along with the accompanying spray water is processed in sumps where the water is separated and recycled to the spray condenser, and the phosphoms and impurities ate settled for subsequent purification. 

The layout specialist should be aware of any special space requirements for a pump. Otherwise, pumps are usually fitted into a small area normally considered adequate for a general pump service. Sump pumps and other special types of appHcations need to be called out. 

Waste facihties should be designed to prevent explosions in sewer systems and typically are comprised of suitable traps, vents, clean-outs, collecting chambers, etc. Flammable gas detectors are installed in sewers to warn of ha2ardous concentrations, and inert gas blanketing of closed process sumps generally is advisable. 

Inks for continuous ink-jet printers typically comprise dyes dissolved in water or solvent having salts added to make the ink conductive for electrostatic charging. Whenever waterproof printing is required, low boiling solvent inks ate used. For printers that ate used in office environments, water is used as the ink solvent. Using water-based inks, humectants may be added to inhibit drying of ink in the sump and surfactants ate added to wet the printing surface. 

The vessel design features a Chinese hat-like conical core stopper above the underflow sump, which is there to prevent the vortex from reaching the latter and reentraining the settled soHds. The core stopper is also beheved to stabilize and locate the vortex flow in the vessel. Overflow from the vessel is through a wide cylindrical insert through the Hd, similar to a vortex finder in a hydrocyclone (16), and an optional provision can be made for collecting any floatables in a float trap. 

Fig. 7. Tank bottom designs (a) flat bottom (b) cone-up bottom (c) cone-down bottom (d) cone-down bottom with sump and (e) single slope. In (c), buried lines are not used frequently because of the difficulty of inspection and possibiHty of accelerated corrosion.

Cleaners. Cleaner formulations can be classified with respect to the abiUty to emulsify oils, keep them in solution or to reject oils, spHt them out of solution. The latter type loosens the oil, and the separated oil does not dissolve but is rejected, and usually floats to the top of the cleaner solution. For the cleaner that rejects oil, the tank needs to be skimmed constantly. This is most easily accompHshed usiag the overflow weir, sump, and recirculating pump arrangement. OH-rejecting cleaners last longer. 

Sump Pumps These are small single-stage vertical pumps used to drain shahowpits or sumps. They are of the same general construction as vertical process pumps but are not designed for severe operating conditions. 

The simple ejector or siphon is widely used, in spite of its low efficiency, for transferring liquids from one tank to another, for lifting acids, alkahes, or solid-containing liquids of an abrasive nature, and for emptying sumps. 

Review causes of vortexiug. Consider iustaUatiou of a vortex breaker such as a bell mouth umbrella or changes to sump design. 

Discharge piping leaking under liquid level in sump-type design. 

At the bottom of the column, a liquid sump of constant and perfectly mixed molar liquid holdup Mg is provided. A portion of the hq-uid flowing from this sump passes to a thermosiphon reboiler, with the... 

The perforated pipe distributor comprises a central feed sump and pipes that branch out from the sump to provide the liquid discharge. The level in the sump varies with liquid total flow rate, and the size of the lateral pipes and their perforations must be determined carefully to ensure that the ends of the pipes are not starved for hquid. The orifices are typically 4 to 6 mm diameter, and can be subject to phigging if foreign matter is present. The pipes must be leveled carefully, especially for large diameter columns. 

Clarmer-Thickener Clarifiers can serve as thickeners, achieving additional densification in a deep sludge sump adjacent to the center that extends a shoi t distance radi ly and provides adequate retention time and pulp depth to compact the solids to a high density. Drive mechanisms on this type of clarifier usually must have higher torque capability than would be supplied on a standard clarifier. 

If individual controllers are used instead of optimal computer control, several strategies are possible. In one strategy (Lynch and Fiber, 3rd IFAC Symposium on Automation of Mining, Mineral and Metal Proce.ssing, 25-32, 1980) the sluri y-pump rate is controlled to maintain sump-level constant, which results in smooth cyclone operation. The water-feed rate is ratioed to the ore-feed rate, which keeps the circiilating load from oscillating. The ore-feed rate is then controlled to maintain product-particle size. 

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