Draw-off boot

The most neglected, but most important, feature of the reflux drum shown in Fig. 26.3 is the riser, a piece of pipe 4 to 12 in high, protruding from the bottom of the drum. You see, water first settles to the bottom of the drum. The water then runs along the bottom of the drum into the water draw-off boot. 

Water is drained off the boot to maintain an interface level between water and hydrocarbon in the boot. These interface level controllers, especially on reflux drum water draw-off boots, are typically set locally. The operator finds the visible interface level in the boot s gauge glass, and then sets the local interface level controller, to hold the level half way down the boot. Level taps in the lower portion of any vessel, tend to plug. This is especially true with the level taps in water draw-off boots. You need to blow out these taps on some frequent basis, because a high boot interface level can push water into the tower s reflux pump. 

Fig. 21.5 shows two waste-heat boilers that are generating superheated, 150-psig steam from a fractionator hot oil pumparound. After years of trouble-free operations, water was observed in the gas-oil pumparound return stream. The symptoms of the water infiltration into the fractionator were an increase in the fractionator pressure and an increase in the water production from the fractionator reflux drum s draw-off boot. 

Draw-off boot A low point in a vessel used to collect water. 

In most services, the water boot LC will have to be run on manual. If there is more than one water draw-off nozzle, only leave one open to the... 

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