Heavy-walled pressure vessel

Working in a good fume hood, suspend the peptide-resin in anhyd iPrOH (20 mL g ) in a heavy-wall pressure vessel. For small runs, a round-bottomed flask can be used if it is in perfect condition, free from nicks and scratches. ChiU the suspension to — 20°C in an ice/ CaCl2 bath and saturate with anhyd NHj from a cylinder, using a KOH trap on the exit tube to prevent entry of moisture. Use a safety trap between the cylinder and the flask and watch constantly to be sure that solvent is not sucked back into the cylinder. Wire a tight rubber... 

Pressure. The reactor operates at atmospheric pressure with coolant boiling points above 1200 C. Although there is a reactor vessel, there is no heavy-wall pressure vessel that limits access to the reactor core. 

The first heavy-walled pressure vessel built entirely by welding was fabricated in 1925. 

Reactions performed at 40 C or higher were mn in sealed, heavy wall pressure vessels with threaded Teflon bushing. 

The vapor pressure of a crude oil at the wellhead can reach 20 bar. If it were necessary to store and transport it under these conditions, heavy walled equipment would be required. For that, the pressure is reduced (< 1 bar) by separating the high vapor pressure components using a series of pressure reductions (from one to four flash stages) in equipment called separators , which are in fact simple vessels that allow the separation of the two liquid and vapor phases formed downstream of the pressure reduction point. The different components distribute themselves in the two phases in accordance with equilibrium relationships. 

Gas processing facilities generally work best at between 10 and 100 bar. At low pressure, vessels have to be large to operate effectively, whereas at higher pressures facilities can be smaller but vessel walls and piping systems must be thicker. Optimum recovery of heavy hydrocarbons is achieved between 20 bar and 40 bar. Long distance pipeline pressures may reach 150 bar and reinjection pressure can be as high as 700 bar. The gas process line will reflect gas quality and pressure as well as delivery specifications. 

Reactions under pressure are usually carried out in an autoclave. However, several simple vessels can be used for reactions at moderate pressure. A heavy walled Pyrex test tube or Kjeldahl flask drawn out and sealed with an oxygen torch makes a suitable container for many Diels-Alder reactions. The tube can be heated in an oil or water bath, but care must be exercised to protect against explosions. At the conclusion of the reaction, the tube is cooled to room temperature, the neck is scratched with a file or carborundum chip, and a hot Pyrex rod is touched to the scratch. A large crack in the neck should result, and the sealed top can be easily knocked off. 

A heavy-walled Pyrex tube with a suitable lip can be sealed with a metal bottle cap and capper available at many hardware stores (Fig. A3.8). This vessel is suitable for reactions at moderate pressure only (for example, benzene heated to 100°). 

A complete methodology for the manipulation and reaction of air-sensitive solutions has evolved around cappable glass pressure bottles. Soft-drink bottles are sometimes used (hence these procedures are sometimes referred to as pop bottle techniques ) however, heavy-walled borosilicate glass pressure reaction vessels are superior. In contrast to the modified standard taper ware discussed above, this pressure apparatus offers advantages where modest pressures are necessary and where the centrifugation of precipitates is preferable to filtration. These techniques are especially popular in the preparative-scale study of catalytic reactions of small molecules, such as olefin polymerization. The pressure bottle is fitted with a cap containing two 1/8 in. holes and a rubber liner, which is secured by means of a hand-operated bottle capper (Fig. 1.31).18... 

Brittle fracture is always a concern with heavy wall vessels. An 80 to 100°F (27 to 38° C) minimum hydrostatic test temperature is often specified to minimize the possibility of brittle fracture during hydrostatic testing. To minimize the possibility of brittle fracture of heavy wall reactors during start up and shutdown, reduced pressure below 200 to 300° F (90 to 150°C) is usually specified. Typical limitations are 40% of the design pressure or 20% of the original hydrostatic test pressure. With the advent of temper embrittlement resistant steels and weld metal, some refiners feel reduced pressure is only required below 100°F (38°C). 

Samples obtained in this manner are transferred at pressures above the bubble point to a heavy-walled, stainless-steel vessel capable of-withstanding high pressures. The volume of this vessel, which is... 

Figure 36-2 is a schematic of a commercial microwave bomb designed to operate at 80 atm, or about 10 times the pressure that can be tolerated by the moderate-pressure vessels described in the previous section. The maximum recommended temperature with this device is 250°C. The heavy-wall bomb body is constructed of a polymeric material that is transparent to microwaves. The decomposition is carried out in a Teflon cup supported in the bomb body. The microwave bomb incorporates a Teflon 0-ring in the liner cap that seats against a narrow rim on the exterior of the liner and its cap when the retaining jacket is screwed into place. When overpressurization occurs, the 0-ring distorts, and the excess pressure then compresses the... 

Table 4-16. High Tensile as Rolled or Normalized and Tempered Alloy Steels for Heavy-Wall Reactors and Pressure Vessels...

Tubular Reactors. Reactions taking place at pressures exceeding 700-800 psi are usually carried out in long tubes or m heavy walled vessels up to several feet in diameter and 50 ft in height. These reactors, for both gas-phase and liquid-phase reactions, are particularly useful where continuous processing is indicated. 

The reaction is carried out in a 150-mL heavy-wall Monel pressure vessel rated to 350 bar, equipped with an 0.25-in. NPT opening and corresponding adapter with a Monel high-pressure valve with PTFE stem packing, rated to 700 bar. About 2 g of pulverized anhydrous nickel(II) fluoride is put into the vessel. The vessel is prefluorinated once or twice with about 500 mbar of fluorine and subsequently once or twice with about 500 mbar of chlorine trifluoride for an hour under occasional heating up to 300-400°C. Into the seasoned reaction vessel, cooled to - I96°C, about 40 mmol of chlorine trifluoride and about 400 mmol of fluorine are condensed. 

Pure sulfamlde (m.p. 93°C 2 g.) is placed in a heavy-wall test tube. A thermometer is Introduced so that the mercury bulb is completely covered with sulfamide. A side arm of the reaction tube, lightly closed with cotton, is used as a pressure equalizer. The tube is slowly heated to 92°C by Insertion to a depth of 5 cm. in an oil bath. When the sulfamide has melted, the temperature is slowly raised to 180°C over a period of one hour. During the second hour, the temperature is increased to 200°C and maintained there for four hours. After a total of six hours of heating, the reaction vessel is removed from the oil bath and allowed to cool. The cold, fused cake of trisulfimide is dissolved in about 20 ml. of water the solution is then diluted with 500 ml. of boiling water. A... 

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