Entry to Vessels

Many people have been killed or overcome because they entered vessels or other confined spaces that had not been thoroughly cleaned or tested. About 63 people are killed this way every year in the United States about 40 of those are would-be rescuers (see Section 11.6) [25]. A number of incidents are described here. Another is described in Section 9.1.5 (c), and others involving nitrogen are described in Section 12.3. Sometimes it seems that vessels are more dangerous empty than full. 

For further details of the procedures that should be followed when preparing vessels for entry, see References 1 and 2. 

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The distinctive odor of trichloroethylene may not necessarily provide adequate warning of exposure, because it quickly desensitizes olfactory responses. EataUties have occurred when unprotected workers have entered unventilated areas with high vapor concentrations of trichloroethylene or other chlorinated solvents. Eor a complete description of proper entry to vessels containing any chlorinated solvent, see ASTM D4276-84, Standard Practice for Confined Area Entry (34). 

Jobs which raise special problems. Such jobs might include entry to vessels and other confined spaces, hot work, and responsibilities of contractors. 

Entry should not normally be allowed to vessels containing irres-pirable atmospheres. Special precautions are necessary if entry is permitted (.see Section 11.5). 

Residence time (of an element of fluid)(Section 2.1) length of time that an element of fluid spends in a vessel (i.e., from entry to exit) a residence time is an age, but the converse is not necessarily true. 

Ikeda et al. [80] have reported a photochemical entry to spiro-(3-lactams 27 (Scheme 8) by the irradiation of a solution of 2 - (/V - ac y I - /V-al k y I a m i n o) eye I o h e x -2-enone 26 in acetone with a 300 W high pressure mercury lamp in a pyrex vessel under nitrogen. The reaction occurred with the intervention of the 1,4-diradical intermediate formed via abstraction of a hydrogen on the N-acyl group by the (3-carbon atom of the ot,(3-enone system. 

The inlet pipes of the two starting reactants to the batch vessel were simply connected to the StarLam mixer [67]. The only difference to the previous feed lines was the installation of filter cartridges before the entries to the microstructured mixer, necessary to avoid blocking of the reactor. The pressure drop in the lines was lower than 3 bar so that it was possible to keep the pumps used before in the plant. At the outlet of the reactor, a tube reactor was installed. During optimization it was found that it is sufficient to insulate this tube to reach the temperature needed to finish the reaction. The pipe ended directly in the batch vessel where the second endothermic reaction step was carried out as before. 

A schematic of a trickle bed reactor is shown in Fig. 19-40. The reactor is a high-pressure vessel equipped with a drain and a manhole for vessel entry. Typical vessel diameters may range from 3 to 30 ft with height from 6 to 100 ft. The liquid enters the reactor and is... 

The lamina propria constitutes a continuous sheet of connective tissue containing collagen, elastic fibres and cellular components in a hydrated ground substance. It also carries blood capillaries and nerve fibres that serve the mucosa. It is through the blood vessels in the lamina propria that drag moieties can gain entry to the systemic circulation. 

Most pressure vessels are side-entry and exit for the feed and concentrate, although some older systems employ end-entry and exit vessels. Side-entry pressure vessels are preferred over end-entry vessels because the amount of piping that must be disconnected to... 

When invading microorganisms have crossed the epithelial barriers they will almost certainly be taken up with lymph in the lymphatic ducts and be delivered to filtration and immune systems at the local lymph nodes. Sometimes this serves to spread infections further around the body. Eventually, spread may occur from local to regional lymph nodes and thence to the bloodstream. Direct entry to the bloodstream from the primary portal of entry is rare and will only occur when the organism damages the blood vessels or if it is injected directly into... 

The inflow will depend on the upstream pressure and specific volume, p] and U, and on the pressure at the entry to the vessel, p. For a horizontal pipe containing a valve, the flow will be given by... 

In 1935 Dr. Mario Biazzi introduced a further method of continuous manufacture based on the use of stirred vessels for the washing stages and characteristic onion-shaped separators with tangential entries to impart a gentle rotary movement to encourage coalescence and separation (19, 20), Most important perhaps was that this particular arrangement was amenable to remote control from a protected position. It was with the introduction of the Biazzi plants that lead was replaced by stainless steel for reactors and subsequent stages. 

Propeller types pump li( uid. Every revolution of a square pitch prop discharges a column of liquid approximately equal to the diamf ter of the propeller. The flow is iixial. Such pumps are used primarily for high-speed applications and side-entry mixers. Duel propellers are used on vessels with H/D ratios greater than 1. The axial flow decreases mLx time. They are heavier and cost more than pitched-blade turbines. Propeller-to-vessel-diameter ratio is usually Vs- A propeller-type impeller is used for high flow. 

Vacuum crystallizers of the type shown in Fig. 8.44b generally produce small crystals (< 300 pm) with a wide size distribution as a result of uncontrolled nucleation caused by a combination of feedstock flashing on entry to the vessel and vigorous agitation. 

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