Filter Hot Washing

The filtration rate of a filter decays over time due to plugging of the filter cloth by small wax crystals. A typical decay curve is shown below. The feed rate measured by flow meter is plotted against the number of DIPS or exposures of the filter cloth to the wax slurry. The shape of the decay curve depends on the filter media, in this case an ExxonMobil proprietary cloth. 

A Ultrasonic Flow Meter Reading — Power CTheoretkal) 

As the filtration rate decays, throughput is lost and at some point the filter must be taken offline and washed to restore the filtration rate. The time that the filter is off-line also represents lost production. The optimum time between washes is the economic balance between production lost due to the decay curve compared to the time to wash the filter and bring it back on line. An example of a series of decays and washes are shown below. If the shape of the decay curve is known and the wash time is known the optimum wash time may be found analytically. 

Hot ketone solvent is used to wash the filters. Cold wash solvent is blocked off and hot solvent flows through the same sprays or drip pipes, over the filter cloth, melting the wax crystals, cleaning the cloth. Filter washings are collected in a filter washing drum. The washings may be  

Injected into the appropriate stage of the DILCHILL crystallizer 

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Methylamine Hydrochloride. 125 g of ammonium chloride and 250 g 40% aqueous formaldehyde solution are placed in a distilling apparatus, with the thermometer well below the surface of the liquid. The mixture is slowly heated to 104° and held at this temp until no more liquid distills. The product in the flask is cooled and filtered from ammonium chloride. The liquid is then evaporated on a water bath to half its original volume and a second crop of ammonium chloride is filtered off. The filtrate is concentrated at 10(T until a crystalline scum forms on the surface. On cooling methylamine hydrochloride separates and is removed by filtration. Further evaporation and cooling produces another crop of methylamine hydrochloride, which is also filtered. The combined yield is treated with boiling chloroform, filtering hot, washed with room temp chloroform, and dried in a vacuum desiccator. Yield 40 g. 

To the suspension of 2.66 g of l-(4-pyridyl)-3-(2-chloroethyl)urea in 4 ml of boiling methanol, 2.68 g of 30.8% methanolic sodium methanolate are added while stirring and the mixture is refluxed for 1 h. It is filtered hot, washed with hot methanol, the filtrate evaporated, to yield the l-(4-pyridyl)-2-imidazolidinone, melting point 204°-207°C, (recrystallized from 90% aqeuous ethanol). 

The precipitate is separated by suction filtration, pressed on the funnel, and washed successively with three 100-ml. portions of water and two 100-ml. portions of 95% ethanol. The product is transferred to a 1-1. Erlenmeyer flask, boiled for 10 minutes with 400 ml. of 60% ethanol with occasional stirring, filtered hot, washed twice with 50-ml. portions of 95% ethanol, and then dried in an oven at 90-100° for 6-12 hours. The crude a-phthalimido-o-toluic acid, which weighs 140-155 g., is divided into two equal portions, and each portion is dissolved in boiling propionic acid (Note 5). Each solution is treated with 1 tablespoon of Norit and filtered through an electrically heated gravity funnel. The filtrates are allowed to cool slowly to room temperature and are then refrigerated overnight. The crystals from the two portions are collected by suction filtration in one funnel and washed on the funnel with 400 ml. of 95% ethanol. The product is dried over potassium hydroxide in a vacuum desiccator. The yield of nearly white crystals of a-phthalimido-o-toluic acid is 126-141 g. (60-67% based on phthalide), m.p. 265.0-266.5°. 

Zeolite A was made following a procedure also described by Rollmann and Valyocsik(4). A solution of sodium aluminate and sodium hydroxide was added to a solution of sodium meta-silicate and stirred at 90°C for 2 to 5 hours. The suspension was then filtered hot, washed, and dried. 

Disulfanylpurine (15.0 g, 0.08 mol) was dissolved in a mixture of distilled H O (250 mL) and coned NH, (50 mL) by warming. Then EtOH-wet Raney Ni (100 g) was rinsed with H O (ca. 100 mL) and added to the purine, and the mixture refluxed for 1.5 h. The catalyst was filtered hot, washed with a little HjO, and the filtrate plus H O wash returned to the reaction fiask and refluxed for 1 h with a second portion of EiOH-wet Raney Ni (100 g) plus additional coned NHj (30 mL). The catalyst was filtered as before and the initially colorless filtrate evaporated to dryness at reduced pressure to give crude purine yield 3.42 g (35%). 

L 2N HCl, decant and wash the aqueous phase three times with CHCI3 dry, evaporate in vacuum (can chromatograph as for (III)) to get about 11 g 4,5,6,7-tetrahydro-4-indolone (IV). 7.35 g (IV), 5 g 10% palladium-carbon, 700 ml mesitylene and reflux eight hours or more. Filter hot, wash precipitate with methanol, cool and evaporate in vacuum (can chromatograph as for (III)) to get 5 g 4-OH-indole (V) (recrystallize from petroleum ether), which can be converted to the diakyltryptamine by any of the methods described here or as follows (the first step leading to (VI) may not be necessary). 5 g (V), 20 ml pyridine, 10 ml acetic anhydride and heat in water bath 10 minutes. Pour on ice, stir and add NaHCOs. After one-half hour extract with ethyl acetate, wash... 

The precipitate is separated by suction filtration, pressed on the funnel, and washed successively with three 100-ml. portions of water and two 100-ml. portions of 95% ethanol. The product is transferred to a 1-1. Erlenmeyer flask, boiled for 10 minutes with 400 ml. of 60% ethanol with occasional stirring, filtered hot, washed twice with 50-ml. portions of 95% ethanol, and then dried in an oven at 90-100° for 6-12 hours. The crude a-phthalimido-... 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

Phthalide. In a 1 litre bolt-head flask stir 90 g. of a high quality zinc powder to a thick paste with a solution of 0 5 g. of crystallised copper sulphate in 20 ml. of water (this serves to activate the zinc), and then add 165 ml. of 20 per cent, sodium hydroxide solution. Cool the flask in an ice bath to 5°, stir the contents mechanically, and add 73-5 g. of phthalimide in small portions at such a rate that the temperature does not rise above 8° (about 30 minutes are required for the addition). Continue the stirring for half an hour, dilute with 200 ml. of water, warm on a water bath imtil the evolution of ammonia ceases (about 3 hours), and concentrate to a volume of about 200 ml. by distillation vmder reduced pressure (tig. 11,37, 1). Filter, and render the flltrate acid to Congo red paper with concentrated hydrochloric acid (about 75 ml. are required). Much of the phthalide separates as an oil, but, in order to complete the lactonisation of the hydroxymethylbenzoic acid, boil for an hour transfer while hot to a beaker. The oil solidifles on cooling to a hard red-brown cake. Leave overnight in an ice chest or refrigerator, and than filter at the pump. The crude phthalide contains much sodium chloride. RecrystaUise it in 10 g. portions from 750 ml. of water use the mother liquor from the first crop for the recrystaUisation of the subsequent portion. Filter each portion while hot, cool in ice below 5°, filter and wash with small quantities of ice-cold water. Dry in the air upon filter paper. The yield of phthalide (transparent plates), m.p. 72-73°, is 47 g. 

Prepare acetophenonephenylhydrazone by warming a mixture of 20 g. of acetophenone (Section IV, 136) and 18 g. of phenylhydrazine on a water bath for 1 hour. Dissolve the hot mixture in 40 ml. of rectihed spirit, and shake or stir to induce crystallisation. Cool the mixture in ice, filter and wash with 12 ml. of rectified spirit. Dry in a vacuum desiccator over anhydrous calcium chloride for at least half an hour. The yield of phenylhydrazone, m.p. 105-106 , is 28 g. 

Method A. Cool a solution of the nitrate-free dichloride, prepared from or equivalent to 5 0 g. of palladium or platinum, in 50 ml. of water and 5 ml. of concentrated hydrochloric acid in a freezing mixture, and treat it with 50 ml. of formahn (40 per cent, formaldehyde) and 11 g. of the carrier (charcoal or asbestos). Stir the mixture mechanically and add a solution of 50 g. of potassium hydroxide in 50 ml. of water, keeping the temperature below 5°. When the addition is complete, raise the temperature to 60° for 15 minutes. Wash the catalyst thoroughly by decantation with water and finally with dilute acetic acid, collect on a suction filter, and wash with hot water until free from chloride or alkali. Dry at 100° and store in a desiccator. 

The mother Hquor from the cmde ferrous sulfate crystallisation contains neady all the chromium. It is clarified and aged with agitation at 30°C for a considerable period to reverse the reactions of the conditioning step. Hydrolysis reactions are being reversed therefore, the pH increases. Also, sulfate ions are released from complexes and the chromium is converted largely to the hexaaquo ion. Ammonium chrome alum then precipitates as a fine crystal slurry. It is filtered and washed and the filtrate sent to the leach circuit the chrome alum is dissolved in hot water, and the solution is used as cell feed. 

In a 500-cc. round-bottom flask fitted with a reflux condenser are placed 68 g. of phenylurea (0.5 mole) (Note i) and 120 cc. (i mole) of 42 per cent hydrazine hydrate solution (Note 2). The flask is heated on a steam bath for about twelve hours. The hot mixture is treated with a small amount of decolorizing charcoal (Norite) and filtered. The charcoal is washed with two 15-CC. portions of warm water and the filtrate and washings are then concentrated on a steam bath to about 100 cc. On coolipg in an ice bath a crop of crystals separates and is collected on a filter and washed with two 15-cc. portions of cold water. The filtrate and washings are concentrated to about 25 cc. and another crop of crystals is obtained as before. The total yield of crude compound is 47-52 g. It is white at first but sometimes turns brown on drying. It usually melts below 115° because of some unchanged phenylurea. 

Because of their zwitterionic nature, amino acids are generally soluble in water. Their solubility in organic solvents rises as the fat-soluble portion of the molecule increases. The likeliest impurities are traces of salts, heavy metal ions, proteins and other amino acids. Purification of these is usually easy, by recrystallisation from water or ethanol/water mixtures. The amino acid is dissolved in the boiling solvent, decolorised if necessary by boiling with Ig of acid-washed charcoal/lOOg amino acid, then filtered hot, chilled, and set aside for several hours to crystallise. The crystals are filtered off, washed with ethanol, then ether, and dried. 

Benzoylbenzoic acid [611-95-OJ M 226.2, m 196.5-198°, 197-200°, pKes 3.7. Dissolve in hot H2O by adding enough aqueous KOH soln till distinctly alkaline, filter and then acidify with drops of cone HCl. Filter off, wash solid with cold H2O, dry at 100°, and recrystallise from EtOH. [J Am Chem Soc 55 2540 1933.]... 

Chloranilic acid (2,5-dichloro-3,6-dihydroxy-l,4-benzoquinone)/57-5S-77 M 209.0, m 283-284° pK l.22, pK 3.01. A soln of 8g in IL of boiling water was filtered while hot, then extracted twice at about 50° with 200mL portions of benzene. The aq phase was cooled in ice-water. The crystals were filtered off, washed with three lOmL portions of water, and dried at 115°. It can be sublimed in vacuum. [J Phys Chem 61 765 1957.] The diacetate has m 182-185° [7 Am Chem Soc A6 1866 1924 Thamer and Voight J Phys Chem 56 225 7952]. 

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