Boil-off

The evaporated mass is the difFerence between the masses at two times  

With the fixed boil-off pressure and the measurement of the filling level, that is, of the hydrogen mass, all state variables of the hydrogen (M2, M3, h ) are known from the T-s-diagram or a data base. From two measurements of the filling level at two times, the evaporating mass can be calculated and thence the heat input Q. For our example of the main tank, evaporating mass and heat input for two cases are shown in Table 1.5. Evaporation losses of the tank here are between 1 and 1.2% per day. 

The term a- A - (Tq—T) corresponds with the transferred heat flow from radiation and convection and is much smaller than the term of the evaporation enthalpy mLHz fHz and can thus be disregarded. The following differential equation results  

Boundary condition t = 0, T= To This results in the following temperature progression  

The chilling process usually requires several minutes and the evaporating hydrogen must generally be considered as a loss. It is disposed of into the environment via a 

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Note on the laboratory preparation of monoethylaniline. Although the laboratory preparation of monomethyl- or monoethyl-aniline is hardly worth whUe, the following experimental details may be useful to those who wish to prepare pure monoethylaniline directly from amline. In a flask, fitted with a double surface reflux condenser, place 50 g. (49 ml.) of aniline and 65 g. of ethyl bromide, and boU gently for 2 hours or until the mixture has almost entirely sohdified. Dissolve it in water and boil off the small quantity of unreacted ethyl bromide. Render the mixture alkaUne with concentrated sodium hydroxide solution, extract the precipitated bases with three 50 ml. portions of ether, and distil off the ether. The residual oil contains anihne, mono- and di-ethylaniline. Dissolve it in excess of dilute hydrochloric acid (say, 100 ml. of concentrated acid and 400 ml. of water), cool in ice, and add with stirring a solution of 37 g. of sodium nitrite in 100 ml. of water do not allow the temperature to rise above 10°. Tnis leads to the formation of a solution of phenyl diazonium chloride, of N-nitrosoethylaniline and of p-nitrosodiethylaniline. The nitrosoethylaniline separates as a dark coloured oil. Extract the oil with ether, distil off the ether, and reduce the nitrosoamine with tin and hydrochloric acid (see above). The yield of ethylaniline is 20 g. 

So now we have this solvent containing ketone, dried with MgS04... Not being able to vac-distill today, took about 50 mis of solvent/ketone and placed in beaker on stir plate and boiled off the solvent. The resulting oil was a nice reddish-orange color. Had a very unique smell too. Took about 2 grams worth of this ail, added to a test tube containing a saturated solution of sodium bisulfite... In less than 60 seconds the oil precipitated into a whitish yellow mass (very similar to what acetone would do if added to a bisulfite solution). Never had this quick of a crystallization. Not... 

Titanium tetrafluoride may be prepared by the action of elemental fluorine on titanium metal at 250°C (5) or on Ti02 at 350°C. The most economical and convenient method is the action of Hquid anhydrous HF on commercially available titanium tetrachloride in Teflon or Kynar containers. Polyethylene reacts with TiCl and turns dark upon prolonged exposure. The excess of HF used is boiled off to remove residual chloride present in the intermediates. 

Residue Curve Maps. Residue curve maps are useful for representing the infinite reflux behavior of continuous distillation columns and for getting quick estimates of the feasibiHty of carrying out a desired separation. In a heterogeneous simple distillation process, a multicomponent partially miscible Hquid mixture is vaporized ia a stiH and the vapor that is boiled off is treated as being ia phase equiHbrium with all the coexistiag Hquid phases. 

Scouring may be conducted on jigs, boil-off machines, or kettles, depending on fabric weight, constmction, and crease tendency ia the rope form. A combination of a synthetic detergent and soda ash is usually used and scouring is conducted at 85—100°C. Certain nylon blends may require less stringent conditions and the use of less alkaline builders, such as tetrasodium pyrophosphate. 

Generator is a component where heat brought to a system in a tube section is used to restore the solution concentration by boiling off the water vapor absorbed in the absorber. 

Closed-cycle liquefier systems. In this design the superconductor resides in a bath of liquid helium and boil-off gas is recirculated through a helium liquefier. The installation of such a system is quite complex but these installations have proved good reliability pro-... 

An extremely violent reaction is observed if the dianion is quenched above 0°C, with ether boiling off at an uncontrollable rate. The submitters observed that if the chiorotrimethyl si lane addition is performed at a lower temperature, the reaction temperature will remain below that of the boiling point of ether. A dry-ice bath made up of 80 20 (v/v) ethanol-water was used the checkers measured a bath temperature of -55 C and kept the reaction in the bath for 16 min before adding chlorotnmethylsilane. 

Ferric sulfate (XH2O) [10028-22-5] M 399.9 + XH2O. Dissolve in the minimum volume of dilute aqueous H2SO4 and allow to evaporate at room temp until crystals start to form. Do not concentrate by boiling off the H2O as basic salts will be formed. Various hydrates are formed the—common ones are the dodeca and none hydrates which are violet in colour. The anhydrous salt is colourless and very hygroscopic but dissolves in H2O slowly unless ferrous sulfate is added. 

A low-boiling-point liquid, in boiling off, has a good heat transfer coefficient to help cool the wall and buy time. Calculate the time required to heat up the liquid and vaporize the inventory. If the time is less than 15 minutes... 

In the event of faults developing (as indicated by high boil-off rates or external frost), cease using the equipment. 

The reduction is carried out much as described in Procedure 2. Ammonia (950 ml) is distilled into a 5-liter reaction flask and 950 ml of /-amyl alcohol and a solution of the ketal in 950 ml of methylcyclohexane are added with good stirring. Sodium (57 g, 2.5 g-atoms) is added in portions. The reaction mixture becomes blue within 30-45 min after the sodium is added and the metal is consumed within about 3 hr after the blue color appears. After the mixture becomes colorless, 200 ml of ethanol is added and the ammonia is allowed to boil off through a mercury trap. Then 500 ml of water and 500 ml 0% potassium bicarbonate solution are added and the organic layer is separated. The organic layer is washed once with 10 % potassium bicarbonate... 

The tetrahydropyranyi ether is prepared and reduced exactly as in Procedures 8a and 8c up to the point at which ethylene dibromide would be added. At this point 27 ml (61.5 g, 0.43 mole) of methyl iodide is added instead the addition requires 1-2 min and should be cautious at first. The mixture is stirred for 1 hr and the ammonia is allowed to boil off overnight. The product is isolated as described in Procedures 8a and 8c except that a larger volume of ethyl acetate is required to dissolve the product than in 8c. After removal of the ethyl acetate, the residual material is crystallized from methanol (400 ml). 

A solution of the 3-ketone hydrate (0.15 g) in acetone- -heptane is heated to boiling. After the acetone has been boiled off, a trace of concentrated hydrochloric acid is added to the -heptane solution and boiled for an additional 2 min. After cooling, the resulting crystals are collected by filtration, washed with dry -heptane and dried in vacuo overnight. Recrystallization from dry -heptane gives 17 -hydroxy-4,4-difluoroestr-5-en-3-one 0.98 g mp 123.5-124.5° [a] 134° (CHCI3). 

By decreasing the pressure and increasing the bottoms temperature more methane and ethane can be boiled off the bottoms liquid and the RVP of the liquid stream decreased to meet requirements for sales or further processing. Typical liquid recovery levels are ... 

The de-methanizer is analogous to a cold feed condensate stabilizer As the liquid falls and is heated, the methane is boiled off and the liquid becomes leaner and leaner in methane. Heat is added to the bottom of the tower using the hot discharge residue gas from the compressors to assure that the bottom liquids have an acceptable RVP or methane content. 

A realistic model of a solution requires at least several hundred solvent molecules. To prevent the outer solvent molecules from boiling off into space, and minimizing surface effects, periodic boundary conditions are normally employed. The solvent molecules are placed in a suitable box, often (but not necessarily) having a cubic geometry (it has been shown that simulation results using any of the five types of space filling polyhedra are equivalent ). This box is then duplicated in all directions, i.e. the central box is suiTounded by 26 identical cubes, which again is surrounded by 98 boxes etc. If a... 

Abknisterung, /. decrepitation, abkochecht, a. fast to boiling, abkochen, v.t. boil, decoct boil off reboil. 

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