Vessels, process shells

Top-Blown Basic Oxygen Process. The top-blown basic oxygen process is conducted ia a cylindrical furnace somewhat similar to a Bessemer converter. This furnace has a dished bottom without holes and a tmncated cone-shaped top section ia which the mouth of the vessel is located. The furnace shell is made of steel plates ca 50-mm thick it is lined with refractory 600—1200-mm thick (11). 

Shell and Tube Heat Exchangers for General Piefineiy Seivices, API Standard 660, 4th ed., 1982, is published by the American Petroleum Institute to supplement both the TEMA Standards and the ASME Code. Many companies in the chemical and petroleum processing fields have their own standards to supplement these various requirements. The Jnterrelation.ships between Codes, Standards, and Customer Specifications for Proce.ss Heat Tran.sfer Equipment is a symposium volume which was edited by F. L. Rubin and pubhshed by ASME in December 1979. (See discussion of pressure-vessel codes in Sec. 6.)... 

A shell of revolution is the form swept out by a line or curve rotated about an axis. (A solid of revolution is formed by rotating an area about an axis.) Most process vessels are made up from shells of revolution cylindrical and conical sections and hemispherical, ellipsoidal and torispherical heads Figure 13.3. 

Escoe, A. K. Mechanical Design of Process Equipment, Vol. 1. Piping and Pressure Vessels. Vol. 2. Shell-and-tube Heat Exchangers, Rotating Equipment, Bins, Silos and Stacks (Gulf, 1986). 

When the shell of a vessel is exposed to extreme heat on the outside and the inside is in contact with vapor, metal temperatures may reach levels where tensile strength will be reduced such that rupture may occur even though the pressure does not exceed the set point of the pressure relief valve [for ordinary carbon steel, this temperature is 900°F (482°C)]. Vapor depressuring provides fire protection for process units by reducing the contained pressure at such a rate that ... 

Improper operation of a process may result in the vessel s exceeding design temperature. Proper control is the only solution to this problem. Maintenance procedures can also cause excessive temperatures. Sometimes the contents of a vessel may be burned out with torches. If the flame impinges on the vessel shell, overheating and damage may occur. 

Shell Stills. At the beginning of the period under review, large quantities of crude oil were processed in tower stills. These were cylindrical vessels 10 to 15 feet in diameter and about 40 feet long. The vessels were mounted horizontally and arranged so that a fire could be applied to the underside (10, 55). The stills were charged with crude oil and the appropriate fractions removed by distillation. The residue was then destructively distilled or coked. Heating was continued until the bottom of the still was at a dull red heat (55). 

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