Wash Distribution

Cold ketone wash is applied to the filters through either sprays or drip pipes or both. There are advantages and disadvantages to both designs and both are in practice today. Cold wash is essential to reduee the Oil in wax, increase dewaxed oil yield and increase the wax product value. 

ExxonMobil patented Drip Pipes provide excellent coverage and are capable of good turndown. Wash falls by gravity onto die wax cake 

Poor Distribution from Conventional Drip Pipe 

Impact of Wash Acolication on Filter Feed Rale fFFRl 

Drying out t compressing wax cake due to lack of wash over part of top pickup zone affects both DWO yield and FFR 

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Despite their theoreticaUy poor washing performance, due to uneven wash distribution and excessive mn-off because the filter surface is not horizontal, many multicompartment dmm filters continue to be used as cake washing filters. Effective washing of the filter cloth can be done only with the belt discharge type, where the cloth leaves the dmm for a brief period and can thus be washed on both sides. 

The problem of localization of the A-factor receptor is now under investigation. The radioactive sample of the A-factor is used which has been prepsured by treatment of synthetjo A-factor with thermally excited tritium atoms. The level of A-factor binding by actinomycete cells was measured after a short-term treatment of 24 hr old mycelium no. 1439 with labelled A-factor. The same amount of A-factor was found to be bound to the cell (approximately 0.18 jug of the A-factor per 1 g of dry mycelium) after the treatment of the mycelium with rather different concentrations of the A-factor and subsequent careful washing. Distribution of the bound A-factor between different cell fractions was determined after destruction of washed mycelium. The A-factor content in cytoplasm was higher than in ribosomes, membranes and envelopes. The preliminary experiments of fractionation of cytoplasmic material showed that the A-factor was bound to proteins. 

Poor wash distribution can result from collapsed sprays creating a wide area without coverage. 

Figure 37. Example Of Poor Filter Cold Wash Distribution (photo by D. S. Sinclair courtesy ExxonMobil Process Research)...

Cold wash, distributed over the wax cake by drip pipes or sprays, will displace the cake liquids, reducing the Oil in Wax and increasing the yield. This occurs in two steps. The first step is a piston displacement where the wash liquid pushes out the cake liquids. In the second step, oil from within the wax crystal diffuses into the low oil concentration wash liquid. The theoretical reduction in oil content may be predicted by the Butler equation . 

Solvent Drip Pipes which are used to distribute the liquid propane wash over the wax cake in the filters, will foul if the water content in the propane is too high. The water freezes and will reduce the wash flow and/or may change the wash distribution. The Oil in Wax will increase and the overall dewaxed oil yield will drop. Methanol or acetone may be added to the propane to deice the drip pipes. 

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

Separation of components in solution. This includes the ordi-naiy objectives of liquid extrac tion, in which the constituents of a solution are separated by causing their unequal distribution between two insoluble liquids, the washing of a liquid with another to remove small... 

A suitable filter is prepared by distributing a slurry of 10-15 g. of Super-Cel in water on a filter paper in a 12-cm. Buchner funnel and washing with water with the aid of suction until a clear filtrate is obtained. 

A feed and wash boxes that may be set in a slight slope so that the distribution over the trapezoidal surface will be proportional to the pan s area. This will ensure that the formed cake is even in thickness and that the applied wash liquids are distributed evenly. 

Strainers may be of the type with an end that continues under the filter bottom. These do promote the formation of an air space for backwashing with air. If this air space is not formed, it can be replaced by a system of pipes that provide for an equal distribution of the washing fluids. 

Absorption Field A system of properly sized and constructed narrow trenches partially filled with a bed of washed gravel or crushed stone into which perforated or open joint pipe is placed. The discharge from the septic tank is distributed through these pipes into trenches and surrounding soil. While seepage pits normally require less land area to install, they should be used only where absorption fields are not suitable and well-water supplies are not endangered. 

The statistical analysis in WASH-1400 suffers from a spectrum of problems, l angmg rom lack of data on which to base input distributions to the invention and the u.se of wrong statistical methods. Even when correct, the analysis is often presented in. so murky a way as to be [Pg.5]

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