Operating problems circulation pump

Flooded refrigeration systems are a version of the closed-cycle design that may reduce operating problems in some appHcations. In flooded systems, the refrigerant is circulated to heat exchangers or evaporators by a pump. Figure 11 shows the flooded cycle, which can employ any of the simple or compound closed-refrigeration cycles. 

It was pointed out earlier that a compression screw pump was used to provide catalyst circulation in the initial 100 /D plant and that it caused serious operating problems. Fortunately the concept of the standpipe to build up pressure was conceived at this opportune moment and was soon put to use. It may seem surprising, but the standpipe concept was only accepted after considerable persuasion and discussion. Confirmation was needed, so a standpipe 100 feet high was set up on one of the refinery fractionation columns at Baton Rouge, filled with catalyst, and aerated. Pressure gauges confirmed the calculated buildup in pressure, and when a valve at the bottom was opened the catalyst ran out as though it were a liquid. 

Turn-down circulation pump (operating problems), 304 Two-phase bottom level problem (flooding), 263, 265-266... 

Use closed-loop systems, which might be installed down-mine , or within settlement basins at a minewater treatment plant. Here the collector fluid circulates in a closed-loop and never comes into contact with the mine water. Likewise, mine water never enters the heat pump or heat exchanger elements. The problem is thus wholly averted, although there are limitations in capacity to closed-loop systems. For larger capacity operations, open systems will be preferred. Furthermore, the exterior of such closed-loop systems may become heavily fouled, necessitating periodic removal for cleaning. 

This process differs from others in several engineering details. The severe duty placed on the reboiler of the aluminum chloride recovery tower due to fouling was a problem which was solved by a vertical thermosyphon reboiler operating ivith sufficient head to provide a high rate of liquid circulation. Another problem was suitable pumps to recycle aluminum chloride slurry to the top of the reactor. Centrifugal pumps with mechanical seals using butane flush were most satisfactory. 

Low boilup [fouling] /circulation rate low/pump problems, see Section 2.3/no vortex breaker/excessive drculation and a wide spread in boiling temperatures in bottoms. Excessive vapor in flash chamber, unstable distillation column operation and apparent underdesign of overhead condenser overdesign. 

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