Mud mixing hoppers also refer to mud blending hopper. They are usually operated together with centrifugal pump. The function is achieved via connection by pipelines and valves.
Mud mixing hoppers
Mud mixing hopper in drilling mud solids control system can be venturi type and swirl type. The popular one is the Venturi hopper. Mud mixing and blending system that utilizes Venturi hopper great power and performance to mix faster, while delivering complete hydration and a more homogeneous, consistent drilling mud that improves drilling and mud mixing efficiency. In addition, mud mixing hopper will reduce overall drilling fluid and mud blending costs by reducing mud mixing product loss through dust recovery and containment.
mud mixing hoppers
Prior to centrifugal pumps use on drilling rigs, the standby reciprocating mud pumps were customarily used to operate the mud hoppers. Mud hoppers are required high-pressure line and connections. From 1950s centrifugal pumps were treated as predominant tool for mud hopper. Another reason of centrifugal pump use in solids control is it does not only mix the mud to be pumped down the bore hole, but also provide the feed pressure and volume required to operate other equipment.
Mud mixing hoppers including both low-pressure and high-pressure. Actually, their working principle is same. Lets take low pressured hopper as example. In low-pressure hopper, drilling fluid velocity is around 10ft/set on the pressure side of the jet nozzle. 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 high-velocity jet stream crosses the gap between the educator nozzle and the downstream venturi and creates a partial vacuum within the mixing chamber (or tee). 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 fluid wets and disperses the mud additives into the fluid stream.
Mud hopper installation and operation
As with any piece of equipment, the mud hopper and related equipment must be sized, adjusted, and installed properly to achieve optimum performance.
Once a mud hopper has been selected, the pump, motor, feed line, and discharge line must be designed to allow the proper flow rate at the recommended head. For example, assume that a mud hopper has been selected that requires 550 gpm (2082 lpm) at 75 feet of head (23 m). With this established, feed- and discharge-line sizes would be determined by recommendations from a recognized authoritative source. The friction head would be determined for all lines and connections at 550 gpm and this would be added to the 75 feet of head for the hopper. The next step is to select a pump and impeller that will provide 550 gpm at the total head required. With the pump selected, the motor size can be determined and adjusted for mud weight. If the maximum mud weight to be used is unknown, it is standard practice in most companies to base all calculations on 20 lb/gal mud (2.4 SG).
Feed and discharge lines of the mud hopper should be kept as short as possible. This is dictated by economics (i.e., less power, piping, and smaller pump) as well as operations. The back pressure from the down- stream piping is crucial to effective operations. When the gap is between 1 and 31 8 inches (25.4 to 79.4 mm) for this particular mud hopper, there is very little difference in barite addition rate. When the gap is larger than 3 1 8 inches, the rate of barite addition is reduced significantly. This further illustrates the need to have equipment and piping sized and adjusted properly.
Another important consideration when installing addition equipment is the amount of lift required. If the discharge goes to a tank on a different deck or there are tall tanks and the hopper is on the ground, mixing rates can be reduced. Sack barite addition is reduced by 17% when the lift is increased from 6 feet to 12 feet (1.83 to 3.66 m). If the lift requirements are severe and the pump is undersized, the mixing capabi- lities will suffer.
From the preceding discussion, it is obvious that the mud hopper can be highly efficient, while improper mud mixing hoppers installations can create many problems. Low addition rates lead to increased rig time and operator hours to treat the mud system. If the discharge from the mud hopper is routed into a tank that is not stirred properly, a large quantity of commercial materials could settle, even if the hopper is properly dispersing and wetting the materials. If the addition system is installed, sized, and adjusted properly, there will be a reduction in system maintenance, a decrease in fluid costs, and a decrease in operator hours