Vacuum insulators

Smaller quantities of liquid nitrogen are shipped in liquid cylinders, which are pressurized stainless steel vacuum-insulated containers with capacities of 160—180 L of hquid nitrogen, producing 100—120 (3800—4600 SCF) gaseous nitrogen when vaporized. Moderate quantities of high pressure gaseous... 

S. Hensley, Vacuum Insulated Pipe, CVI, Inc., Columbus, Ohio, personal communication, 1994. 

R. V. Latham, ed.. High Voltage Vacuum Insulation Basic Concepts and Technological Practice, Academic Press, Inc., New York, 1995. 

Vacuum Insulation Heat transport across an evacuated space (1.3 X lO"" Pa or lower), is by radiation and by conduction through the residual gas. The heat transfer by radiation generally is predominant and can be approximated by... 

C. Cyclobutanone (Note 16). The residue consisting of oxaspiro-pentane (35%) and dichloromethane (about 200 ml.) is added dropwise at room temperature to a magnetically stirred solution containing about 5-10 mg. of lithium iodide in 50 ml. of dichloromethane (Notes 17, 18), at such a rate as to maintain gentle reflux of the solvent. At the end of the addition when the reaction mixture returns to room temperature, the transformation into cyclobutanone is complete. The dichloromethane solution is washed with 20 ml. of saturated aqueous sodium thiosulfate and with 20 ml. of water. After drying over magnesium sulfate and concentration by distillation of the solvent through a 15-cm., helix-packed, vacuum-insulated column, the residual liquid consists of cyclobutanone (95%) and of 3-buten-2-one and 2-methylpropenal... 

In order to control the three factors determining heat transfer, much effort has been spent on developing vacuum insulation for high—temperature batteries involving the use of microporous powders pressed to boards, glass fiber boards, or multifoil insulation. 

An early CO distillation pilot plant described by Johns (in London (1961), reading list), used a two section vacuum insulated column packed with wire gauze rings. The upper section was 5.2 m long with a diameter of 3.2cm, the lower 4.6 m x 1.9 cm. The column contained about 600 plates. An intermediate boiler re-evaporated part of the downward flowing liquid at the junction. This plant accumulates product in the liquid and enriches toward the bottom. Enriched CO (0.4 g day-1 of 65% 13C and 0.05 g day-1 of 5% lsO) was withdrawn from the bottom... 

Liquid hydrogen must be stored in highly insulated containers similar to those used for liquefied natural gas. These containers are made from stainless steel and may be spherical or cylindrical in shape. The containers are double-walled to allow use of vacuum insulation in addition to insulation to prevent heat transfer from conduction, convection, and radiative sources. Pressure relief devices are incorporated to release hydrogen should the internal pressure of the tank increase to the maximum safe operating limit. 

Vertical vacuum-insulated tank (small capacity, pressurised)... 

Pressure building vaporiser (only for vacuum insulated tanks)... 

Figure 18 The principle of stationary vacuum-insulated vertical LNG-storage tank...

LNG tanks for rail transport are by units of around 120 m3 net LNG capacity as shown on Figure 20. Vacuum insulated double wall tanks are usually used. Budget price 500 000 Euro. 

ISO LNG containers are typically 18 m3 net LNG capacity as shown on Figure 21. Such tanks are usually vacuum insulated and made for different pressure classes - typically 10 to 22 bar. Holding time is up to more than 100 days. Budget price 150 000 Euro. 

Dewar Any cryogenic container shielded by a vacuum-insulated space. 

Cryogenic fluid transfer lines are generally classified as one of three types uninsulated, foam-insulated lines, and vacuum-insulated lines. The latter may entail vacuum insulation alone, evacuated powder insulation, or multilayer insulation. A vapor barrier must be applied to the outer surface of foam-insulated transfer lines to minimize the degradation of the insulation that occurs when water vapor and other condensables are permitted to diffuse through the insulation to the cold surface of the lines. 

Cryogenic level measurement in vacuum-insulated tank. 

R. Latham High voltage vacuum insulation, Academic Press (1981)... 

The checkers used a silvered, vacuum-insulated column 30 cm in length with 1.5-cm i.d., filled with 4x4 mm helices distillation of CH2C12 was first done from a 250-mL, two-necked flask with dropping funnel from which the dried extraction solution was continuously added. When ca. 50-mL total volume of solution remained (bath temperature ca. 90°C), it was transferred into a 100-... 

B. Cyclopropanecarboxaldehyde. A 50-mL distilling flask equipped with a receiver cooled to -20°C with a dry ice-methanol bath is charged with 34 g (0.39 mol) of a crude mixture of both cis-and trans-1,2-cyclobutanediol and 10 pL of boron trifluoride butyl etherate (Note 8). The mixture is heated to 230°C with a metal bath. Drops of liquid appear on the condenser, and the aldehyde and water distil into the receiver. The temperature of the distillate oscillates between 50°C and 100°C. Each time the distillation stops, 5-10 pL of boron trifluoride butyl etherate is added to the distilling flask (Note 9). The distillate is transferred into a separatory funnel and sodium chloride is added. The organic layer is decanted and the aqueous layer is extracted three times with 25-mL portions of methylene chloride. The combined organic solution is dried over sodium sulfate, and the solvent is removed by distillation through a 15-cm, helix-packed, vacuum-insulated column. The residue con-... 

The reaction mixture is poured into a 2-L separatory funnel and extracted with four 200-mL portions of methylene chloride (Note 4). The extracts (the lower phase) are combined, dried over anhydrous magnesium sulfate containing a small amount of anhydrous potassium carbonate (to remove traces of hydrochloric acid), and filtered, and the filtrate is concentrated by distillation through a vacuum-insulated silvered column (20-cm length, 1-cm i.d.)... 

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