This reduces lumping of material and is an initial shear of the additives. The high-velocity fluid wets and disperses the mud additives into the fluid stream. This low-pressure area within the tee, along with gravity, actually draws mud materials from the hopper into the tee and fluid stream. The high-velocity jet stream crosses the gap between the eductor nozzle and the downstream venturi and creates a partial vacuum within the mixing chamber (or tee). The pressure line is reduced in size usually from 6 to 2 inches (152 to 51 mm) and exits the jet nozzle at a much higher velocity but lower pressure. The fluid velocity in a low-pressure mud hopper will be around 10 ft/sec on the pressure side of the jet nozzle. Since highpressure hoppers work in the same manner, this discussion will be limited to low-pressure equipment.
It also released the standby main pump from mud mixing duty.Ī low-pressure mud hopper is shown in Figure 1.
Savings were realized through reduced piping cost and higher addition rates that lowered operating cost. This permits the use of lowpressure equipment and the movement of large volumes of fluid rapidly.
Since the 1950s the centrifugal pump has been the predominant tool for charging mud hoppers on drilling rigs. This, of course, would limit the speed of material addition. The jet velocity was suitable for adequate mixing, but the volume was usually less than 500 gpm. A small orifice in the hopper delivered a low flow at a high velocity. This was costly because the pump required enormous power and expensive piping. As with high pressure mud guns, this required high-pressure pipe and connections. Prior to the use of centrifugal pumps on drilling rigs, the standby reciprocating mud pumps were customarily used to operate the mud hopper.
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