Reactors Pipe-loop

From the molten salt 9 m storage tank, which is equipped with heating elements as well as the piping loop circuit, the molten salt is punned to the furnace to be heated, circulates then into the reactor heating plates and flows back into the tank. The total surface area occupied by the process equipment, excluding the biomass and product storage rooms, is equivalent to 850 m split into two floors,... 

The right picture in Figure 228 shows a similar stage of swelling in a commercial reactor. A "log" of about 2-ft diameter was sawed into sections for disposal. In this case, the log solidified into a hard cylinder that shrank slightly upon cooling and therefore could be easily pulled out of the vertical pipe-loop reactor section. 

Applicable design codes are found in Table 5.2-1. The reactor coolant loop piping is designed and analyzed for all transients specified in Section 3.9.1. In addition, those nozzles subjected to local thermal transients, caused by fluid entering the Reactor Coolant System from an auxiliary system, are analyzed to ensure that the nozzles can accommodate the additional transients. 

Reactor CSTR Pipe loop reac- Fluidised bed... 

June 27, 1972 (UN-lOO-N-5) - An unplanned release occurred from a leak in the piping between the recirculation pump and the 116-N-2 tank. Evidence indicated that a failure occurred in the underground section of this pipe, causing discharge of approximately 340,000 L (90,000 gal) of radioactive chemical waste to the ground. The low-level radioactive wastewater contained decontamination chemicals used in the decontamination of the N Reactor primary loop. The waste contained 35 Ci of activity, 26 Ci of which were Co. 

The high-inertia reactor coolant pumps are highly reliable, low-maintenance, hermetically sealed pumps, which circulate the reactor coolant through the reactor core, loop piping, and steam generators. The motor size is minimized through the use of a variable speed controller to reduce motor power requirements during cold coolant conditions. 

Phillips Pilot PlantVertical Pipe-Loop Reactor Design... 

In June of 1958, a 95-gallon vertical pipe-loop, pilot plant reactor was installed and placed into operation with the objective of solving the reactor wall-fouling problems encoxmtered with the stirred-tank autoclave reactors. 

The first United States patent that described the vertical pipe-loop slurry polymerization reactor illustrated in Figure 5.11 was issued to Donald D. Norwood on April 26,1966, as U.S. Patent 3,248,179 and assigned to Phillips Petroleum Company. Earlier applications filed in 1959 were abandoned, thus explaining the relatively late issue date on the Norwood patent. Although Donald Norwood was the only name on the first United States patent issued to Phillips Petroleum, Philips Petroleum credits three process engineers, D. D. Norwood, S. J. Marwil and R G. Rohling, for the design of the vertical loop reactor [24]. 

The agitators necessary in the autoclave reactor were no longer required in the vertical pipe-loop system as a new design was disclosed in U.S. 

U.S. Patent 3,152,872 issued to J.S. Scoggin and Harvey S. Kimble on October 13, 1964, and assigned to Phillips Petroleum Company, provides a detailed description of the separation system used to isolate the solid polyethylene granular particles from the liquid diluent used in the vertical pipe-loop reactor. The contributions of Scoggin and Kimble were important in the design and start-up of the first commercial loop reactor in Pasadena, Texas, in 1961. It should be noted that the first vertical loop reactor used n-pentane as the slurry solvent, which was later changed to isopentane and then to isobutane in about 1970. 

The 95-gallon, pilot-plant, vertical pipe-loop reactor was designed to eliminate the problem of polymer build-up on reactor surfaces found in the stirred tank auoclave designs by circulation of the reacting slurry around a closed loop at a velocity sufficient to keep the polymer particles suspended. This design was the critical technical development that led to the introduction in 1961 of the Phillips vertical-loop, particle-form reactor on a commercial scale, which is illustrated in Figure 5.12. 

Operation of the Phillips Pilot Plant Pipe-Loop Reactor... 

A detailed description of the Phillips pilot plant pipe-loop slurry reactor (Figure 5.11) is found in U.S. Patent 3,248,179. The design consisted of three 4.5 foot, 10 inch, inner-diameter sections and one 4.5 foot, 12 inch inner-diameter pipe which contained the reactor pumping unit as one of the two vertical sections of the design, with either n-pentane or n-hexane as the slurry solvent. 

The IC system is divided into two independent trains, with each train consisting of a piping loop running from the reactor outlet, to heat exchangers located in the reserve water pool, and returning to the reactor inlet. The system is pressurized and on hot standby under normal reactor operations. A connection valve is located on the system s low point near the reactor inlet and is closed under normal reactor operations. The closed valve disrupts the flow through the system to minimize heat loss. 

The slurry reactor was developed by Hochst to make polyethylene using Ziegler catalysts. The reaction medium, called a diluent , is a hydrocarbon that is a solvent for the monomer but not for the polymer. The product is thus formed as a suspended powder. Bimodal products, i.e., products that are, in effect, blends of two polymers having distinctly different molecular weight distributions, can be made using a cascade of two reactors in which the reaction conditions are substantially different [116]. Phillips Petroleum later developed a pipe-loop slurry reactor for use with its chromium oxide catalyst, which required moderately high temperatures and pressures to accommodate the isobutane diluent used. 

The Spacecraft Module shall be capable of rejecting [682] kWt of heat from the Reactor Module. (Level 3 Requirement) This is a place-holder requirement that captures the need to reject waste heat to the space environment via the radiators. The PSEP must accommodate the piping to and from the gas cooler and accommodate the differential expansions that will occur as the HRS and Brayton piping loops approach different temperatures, as well as the more moderate temperatures of any non-operating loops. 

One of the most efficient implementations of the slurry process was developed by Phillips Petroleum Company in 1961 (Eig. 5). Nearly one-third of all HDPE produced in the 1990s is by this process. The reactor consists of a folded loop with four long (- 50 m) vertical mns of a pipe (0.5—1.0 m dia) coimected by short horizontal lengths (around 5 m) (58—60). The entire length of the loop is jacketed for cooling. A slurry of HDPE and catalyst particles in a light solvent (isobutane or isopentane) circulates by a pump at a velocity of 5—12 m/s. This rapid circulation ensures a turbulent flow, removes the heat of polymeriza tion, and prevents polymer deposition on the reactor walls. 

Phillips Petroleum Company developed an efficient slurry process used for the production of both HDPE and LLDPE (Eig. 6). The reactor is built as a large folder loop containing long mns of pipe from 0.5 to 1 m ia diameter coimected by short horizontal stretches of pipe. The reactor is filled with a light solvent (usually isobutane) which circulates through the loop at high speed. A mixed stream containing ethylene and comonomers (1-butene,... 

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