Boiler Circulating Pumps

The forced circulation, or controlled circulation, boiler requires the use of circulating pumps that take their suction from a header connected to several downcomers, which originate from the bottom of the boiler drum and discharge through the various tube circuits operating in parallel (Figure 42). The circulating pumps therefore must develop a pressure equivalent to the frictional losses through these tube circuits. Thus, in the case of different boilers operating in pressure ranges from 1800 to 3000 lb/in2 (124 to 207 bar), the boiler circulating pump must handle feedwater from 620 to 690°F (326 to 365°C) under a suction pressure of 1800 to 2900 lb/in2 (124 to 200 bar). Such a combination of high suction pressure and high water temperature at saturation imposes very severe conditions on the circulating pump stuffing boxes, making it necessary to develop special designs for this part of the pump.

The net pressure to be developed by these pumps is relatively low, ranging from 50 to 150 lb/in2 (3.4 to 10.3 bar). Hence these are single-stage pumps with single-suction impellers and a single stuffing box. The high boiler pressure imposes an extremely severe axial thrust on the

Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

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