High Pressure Reactors

This high-pressure reactor system is designed for fhe use of interchangeable steel pressure vessels. Safety features guarantee safe reactions under pressure. 

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Commercially, urea is produced by the direct dehydration of ammonium carbamate, NH2COONH4, at elevated temperature and pressure. Ammonium carbamate is obtained by direct reaction of ammonia and carbon dioxide. The two reactions are usually carried out simultaneously in a high pressure reactor. Recendy, urea has been used commercially as a catde-feed supplement (see Feeds and feed additives). Other important appHcations are the manufacture of resins (see Amino resins and plastics), glues, solvents, and some medicinals. Urea is classified as a nontoxic compound. 

The Stainicaibon process is described in Figures 3—7. The synthesis section of the plant consists of the reactor, stripper, high pressure carbamate condenser, and a high pressure reactor off-gas scmbber. In order to obtain a maximum urea yield pet pass through the reactor, a pressure of 14 MPa (140 bar) and a 2.95/1 NH —CO2 molar ratio is maintained. The reactor effluent is distributed over the stripper tubes (falling-film type shell and tube exchanger) and contacted by the CO2, countercurrendy. This causes the partial NH pressure to decrease and the carbamate to decompose. 

Another common situation is batch hydrogenation, in which pure hydrogen is introduced to a relatively high pressure reactor and a decision must be made to recycle the unabsorbed gas stream from the top of the reactor or use a vortexing mode for an upper impeller to incorporate the gas from the surface. 

The reaction section consists of the high pressure reactors filled with catalyst, and means to take away or dissipate the high heat of reaction (300-500 Btu/lb of olefin polymerized). In the tubular reactors, the catalyst is inside a multiplicity of tubes which are cooled by a steam-water condensate jacket. Thus, the heat of reaction is utilized to generate high pressure steam. In the chamber process, the catalyst is held in several beds in a drum-type reactor with feed or recycled product introduced as a quench between the individual beds. 

Figure 9.32. Experimental set-up (a) Machinable ceramic holders and two proton conducting pellets showing the location of catalyst, counter and reference electrodes, (b) Twenty four pellet unit, (c) High-pressure reactor, gas feed and analysis unit.43 Reprinted with permission from the American Chemical Society.

This electrochemical promotion study was novel in three respects a) The catalyst-electrode was a fully promoted industrial catalyst, (b) The study was carried out at high pressure (50 atm), (c) This was the first attempt for the scale-up of an electrochemically promoted reactor since 24 CaZro.9Irio.1O3m cell-pellets, electrically connected in parallel, were placed in the high pressure reactor (Fig. 9.32).43... 

The important message here is that the overall performance of the reactor may be improved by using an assembly of catalysts that varies though the reactor bed. To what extent such approaches will become viable depends on the cost of varying the catalysts and the savings realized by reducing the size of the high-pressure reactor. 

Propose a strategy for bridging the gap between the world of adsorption and reaction on well-defined single-crystal surfaces and the world of supported catalysts in high-pressure reactors. 

Reactions were carried out in liquid phase in a well-stirred (1000 rpm) high-pressure reactor (Parr Instruments, 300 mL) at 30 bar and 150°C with 370 mg catalyst for two hours, unless otherwise specified. The feed consisted of the amine with slight excess of ketone at ketone/amine-group molar ratio of 1.6 while maintaining a reaction volume of about 150 mL. In a typical experiment, 576 mmol of aniline is mixed with 920 mmol of cyclohexanone and 370 mg of BS2 catalyst in the 300 mL reactor. The reactor is closed and then pressure-tested to 50 psi above operating pressure to ensure that the system is leak proof Once pressure-tested, the headspace is replaced... 

Hydrogenations. Hydrogenation was accomplished using a Series A000 Parr High Pressure Reactor. The polymers were end-capped before... 

This study shows that the optimization of process conditions could be achieved rapidly by a judicious use of statistics and parallel reactors. A two-level factorial method with two center points was used to limit the total number of experiments to ten. Using two identical high-pressure reactors in parallel further shortened the time required to conduct these experiments. For the model reaction of phenol hydrogenation over a commercially available Pd/C, it was experimentally determined that the optimal yield was 73% at 135 °C, 22.5 bar, and 615 ppm w/w NaOH... 

Ionomers are made in a two-stage process. In the first step, we copolymerize ethylene with small amounts of an organic acid containing a vinyl group, such as acrylic or methacrylic acid, in a high pressure reactor. In the second step, we neutralize the acid comonomers to form metal salts. We can create ionomers with a variety of metal salts, including sodium, calcium, and zinc. 

Figure 7.2 Schematic diagram of the high-pressure high-temperature STM reactor/UHV system. (1) View window, (2) mounting framework, (3) docking scaffold, (4) docking disk, (5) high-pressure reactor (STM body...

The STM body (Figure 7.3b) is the key component of the high-pressure reactor. It includes a coarse approach system, a scanning tube, a receiver for the tip holder,... 

Figure 7.3 High-pressure reactor and STM body, (a) A view of the whole reactor ...

Figure 7.6 schematically shows the setup of gas introduction for the high-pressure reactor. For gas introduction, the male part of a Swagelok fitting (4 in Figure 7.6) is welded on a 1/8 in. tube of the cell lid (3 in Figure 7.6). A 1/32 in. PEEK tube...

Halogen lamp, (2) elliptical reflector, (3) sapphire window welded at the center of the bottom of the high-pressure reactor, (4) the assembled sample, (5) high-pressure reactor. Turquoise dashed line shows the alignment of light beam and sample center. 

In Section 2.2 (this Chapter), we mentioned the difficulties in trying to comply with the new specifications by using single reactor units. From the above discussion, it appears that a second (high-pressure) reactor, with H2S (inter-reactor) scrubbing facilities is the way to go. 

The experiments were carried out in a high-pressure reactor system [8]. 

Schematic diagram of the continuous experiment high-pressure reactor. (Adapted from Shiying, L., Michiaki, H., Yoshizo, S., and Hiroyuki, H., Continuous Experiment Regarding Hydrogen Productionby Coal/ CaO Reaction with Steam (HyPr-RING), 21st Pittsburgh Coal Conference, Osaka, Japan, Sep. 13-17,2004.)...

A dangerous high-pressure reactor situation occurs only when both the alarm system and the shutdown system fail. These two components are in parallel. For the alarm system the components are... 

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