Entrained liquor

There are two serious problems associated with continuous tar distillation. Coal tar contains two types of components highly corrosive to ferrous metals. The ammonium salts, mainly ammonium chloride, associated with the entrained liquor remain in the tar after dehydration, tend to dissociate with the production of hydrochloric acid and cause rapid deterioration of any part of the plant in which these vapors and steam are present above 240°C. Condensers on the dehydration column and fractionation columns are also attacked. This form of corrosion is controlled by the addition of alkali (10% sodium carbonate solution or 40% caustic soda) to the cmde tar in an amount equivalent to the fixed ammonia content. 

The oxidation experienced by the system amounted to an equivalent of 10% of the SO2 removed. Approximately 7% of the oxidized sulfur left the system in the form of CaSOi and the remaining 3% in the form of Na2S0it with the entrained liquor in the cake. 

IB. Hydrogen. Low-pressurehydrogeniseasily handled, but designers and operators should be aware that there is always liquid in a hydrogen header. At its most iimocuous, this is simply water that condenses as the gas cools. Entrained liquor from the cells can make the liquid in the pipe conductive. In a mercury-cell plant, there is the added complication of liquid mercury condensing in the lines. 

There is always a cratain amount of entrained liquor in the gas leaving the cells. This is in the form of a mist that has been known to survive beyond the gas coolers and into the drying system, and deposits can form in the chlorine piping and processing equipment. Also, the sulfuric acid used in the drying system is notorious as a source of mist that can interfere with the performance of downstream equipment. Mist eliminators installed both before the coolers and after the drying towers alleviate these problems. Section 9.1.5 covers this subject... 

Air flow entrains a lot of the discharged centrate. This entrained liquor has a propensity to migrate around baffles. Thus the bottom of the casing is generally slightly sloped to drain any spilled liquor back to the centrate. In thickening applications, the slope will be in the opposite direction, as a little extra dirty liquor in a fluid cake is preferable to dirty liquor in a clean centrate. 

Municipal Garbage Incinerator Flue Gas — 170 77 — E E E from secondary chamber after passing through scrubber marble bed plus entrained liquor at pH 3-4, extensive aeration... 

Their area s evaporation rate was 1270-1780 mm (50-70 in.)/yr, and the rainfall very little most years (10-30 mm), but on rare occasions there were heavy storms. The solar radiation in the area was 6.3 X 10 cal/m /day, the relative humidity as low as 5%, and moderately intense winds arose in the afternoons. Brine was initially pumped at 1000 gpm from three wells that were 30 m (100 ft) deep to fill the ponds to an average 38 cm depth (Anon., 1984a). After the halite ponds the brine was mixed with calcium chloride and end-liquor from the processing plant to precipitate gypsum and some of the boron, with the precipitate being washed to recover some of the entrained liquor s lithium content. The salt was harvested from the halite ponds once per year and placed in stockpiles, while... 

Disk or cascade evaporators are used in the pulp and paper industry to recover heat and entrained chemicals from boiler stack gases and to effect a final concentration of the black liquor before it is... 

F — 50)° (Standiford, Chemical Engineers Handbook, 4th ed., McGraw-Hill, New York, 1963, p. 11-35). Higher values of/c (to about 0.15) can be tolerated in the falhng-film evaporator, where most of the entrainment separation occurs in the tubes, the vapor is scrubbed by liquor leaving the tubes, and the vapor must reverse direction to reach the outlet. 

Knitted wire mesh serves as an effective entrainment separator when it cannot easily be foiiled by sohds in the liquor. The mesh is available in woven metal wire of most alloys and is installed as a blanket across the top of the evaporator (Fig. ll-122d) or in a monitor of reduced diameter atop the vapor head. These separators have low-pressure drops, usually on the order of 13 mm [ M in) of water, and collection efficiency is above 99.8 percent in the range of vapor velocities from 2.5 to 6 iti/s (8 to 20 ft/s) [Carpenter and Othmer, Am. nsi. Chem. 

The tube proportions in the basket evaporator are about the same as in the standard vertieal. One important feature of the basket-type evaporator is the ease with which a deflector may be added in order to reduce entrainment from spouting. The boiling in the vertical-tube evaporator is quite violent, and this tends to cause entrainment losses. This condition is accentuated if the liquor level in the evaporator is low. A baffle such as shown in Figure 9 largely prevents these losses and is much more easily added to the basket type than to the standard type. Other differences between the standard and the basket type are largely details of construction. 

Fluidized-bed process incinerators have been used mostly in the petroleum and paper industries, and for processing nuclear wastes, spent cook liquor, wood chips, and sewage sludge disposal. Wastes in any physical state can be applied to a fluidized-bed process incinerator. Au.xiliary equipment includes a fuel burner system, an air supply system, and feed systems for liquid and solid wastes. The two basic bed design modes, bubbling bed and circulating bed, are distinguished by the e.xtent to which solids are entrained from the bed into the gas stream. 

D,L-Menthol is separated from the mixture by distillation, then converted into the benzoate which is resolved by crystallization with entrainment (see Section 2.1.). The mother liquor and the unnatural diastereomers are recycled by dehydrogenation3. 

A suspension of 33 (10.1 g, 55 mmol) in acetone (1L) was refluxed for 4h, and the acrylonitrile was entrained when formed by distillation of the solvent while fresh acetone was added in order to maintain the initial volume. /V-Hydroxy-L-proline 34 crystallized upon cooling yield 3.6 g (50%) mp 157-160 °C (dec) [a]D28 —79.6 (c 2.18, H20). Unreacted 33 recovered in the mother liquor could be recycled. 

The effectiveness of the separation can be quantified by an efficiency, q, which is defined as the actual increase in raffinate concentration divided by the increase expected from the altered solution volume. For example, if half of the feed solution is absorbed by the gel and the raffinate has twice the feed concentration, then the efficiency would be 100%. The efficiency is primarily a measure of how well the solute is excluded from the polymer network of the geL The efficiency can be reduced, however, by physical entrainment of raffinate solution around the gel particles. The entrained solute can be recovered by washing the swollen gel and adding the wash liquor to new feed. 

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