Holding tanks

The emulsion process can be modified for the continuous production of latex. One such process (68) uses two stirred-tank reactors in series, followed by insulated hold-tanks. During continuous operation, 60% of the monomers are continuously charged to the first reactor with the remainder going into the second reactor. Surfactant is added only to the first reactor. The residence time is 2.5 h for the first reactor where the temperature is maintained at 65°C for 92% conversion. The second reactor is held at 68°C for a residence time of 2 h and conversion of 95%. 

Single-pass conversions of acetone cyanohydrin are 90—95% depending on the residence times and temperatures in the generator and hold tank. Overall yields of product from acetone and hydrogen cyanide can be >97%. There are no significant by-products of the reaction other than the sodium salts produced by neutralization of the catalyst. 

It is unusual to find a hazardous-waste-transfer facility at which wastes are simply transferred to larger transport vehicles. Some processing and storage facihties are often part of the materials-handliug sequence at a transfer sec tion. For example, neutralization of corrosive wastes will resiilt in the use of lower-cost holding tanks on transport vehicles. 

Solvent reeovery systems would also neeessitate the speeifieation of eondenser duties, distillation tower sizes, holding tanks, piping, and valves. It is important to note that the engineering design of an adsorption system should be based on pilot data for the partieular system. Information ean usually be obtained direetly from the adsorbent manufaeturer. The overall size of the unit is determined primarily by eeonomie eonsiderations, balaneing the operating eosts against the eapital eosts. 

When solution must be pumped, consideration should be given to use of holding tanks between the dry feed system and feed pumps, and the solution water supply should be controlled to prevent excessive dilution. The dry feeders may be started and stopped by tank level probes. Variable-control metering pumps can then transfer the alum stock solution to the point of application without further dilution. Means should be provided for calibration of the chemical feeders. Volumetric feeders may be mounted on platform scales. Belt feeders should include a sample chute and box to catch samples for checking actual delivery with set delivery. Gravimetric feeders are usually furnished with totalizers only. Remote instrumentation is frequently used with gravimetric equipment, but seldom used with volumetric equipment. 

Septic Tank Untreated liquid household wastes (sewage) will quickly clog your absorption field if not properly treated. The septic tank is a holding tank in which this treatment can take place. When sewage enters the septic tank, the heavy solids settle to the bottom of the tank the lighter solids, fats and greases partially decompose and rise to the surface and form a layer of scum. The solids that have settled to the bottom are attacked by bacteria and form sludge. 

Liquid nitrogen should always be analyzed before it is off-loaded. The same applies in other cases where delivery of the wrong material could have serious unwanted results, such as a fire or runaway reaction, as in the two incidents that follow. If analysis causes too much delay, the new load should be put in a holding tank. 

Some accidents can be attributed to structural failures. On October 20, 1944, one of the four liquid gas tanks at tlie East Ohio Gas Company in Cleveland began to leak. The plant converted natural gas to tlie liquid form, which was stored for emergency use in holding tanks. If needed, tlie liquefied product could be reconverted to its gaseous state tuid fed into the city distribution lines. The tanks were constructed in 1941 and luid a capacity of more tlian 400,000 cubic feet of liquid. 

Figure 12-5. The Lummus Crest Inc. process for producing polystyrene " (1) reactor, (2) holding tank (Polystyrene beads and water), (3) centrifuge, (4) pneumatic drier, (5) conditioning tank, (6) screening of beads, (7,8) lubrication and blending, (9) shipping product.

The water authority may limit the quantity of final treated effluent, and monitoring of the final out-fall may have to be considered in conjunction with a holding tank. 

Suitable pumps may be required to pump from holding tanks into licensed contractor vehicles. 

Cold Solvents Solvents, for example, white spirit or paraffin, used either by immersion or by manual application are not to be recommended as effective, or particularly safe methods, of degreasing. When used by immersion, the holding tank can became heavily contaminated with soil, which will remain on the work after the solvent has evaporated. The use of solvent-soaked rags, although a time-honoured procedure, is now being frowned upon on the grounds of operator safety aqueous based pre-wipes are available. 

The need for good chemical resistance is no longer as great as it used to be. Under current waste water rules, most powerful chemicals may no longer be disposed of in a sink. Grood resistance, however, will be needed in cases where sinks do not drain to the sewer but to a waste holding tank which is pumped out by a waste disposal service. 

Proton transfer occurs as well as solid formation.) (c) How many kilograms of lime are required to remove all the phosphoms from a 1.00 X 10 L holding tank filled with contaminated water that is... 

Radioactive tracers can show flow pathways that cannot be detected using other methods of detection. Tritiated water added to a holding tank results in radioactivity in the water from wells that draw from the ground water supply into which the holding tank drains. 

To start the recycling system assay, 1200 L of water and 600 mL of the technical enzyme (0.5 mL enzyme/L of water) were added to the 2500 L holding tank. A periodical addition of water and enzyme at the same concentration was necessary to compensate for losses caused by the peel residues and centrifugation. The open system assay was performed in the normal way as reference, without recycling or enzyme addition. 

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