Mud pumps need to be carefully sealed during operation. There are three sealing methods available, but how do you choose the right one?
The most important thing is to understand the characteristics of each sealing method and choose the one that fits your specific situation.
Firstly, the most common form of sealing is the primary packing seal. It is devised as a water seal on the shaft and continuously presses water into the packing to prevent mud leakage. Multi-stage pumps are best suited for packing seals. The structure is simple, easy to maintain, and inexpensive.
Secondly, the impeller's seal relies on the reverse centrifugal force of the impeller to prevent mud leakage. When the inlet pressure of the pump is less than 10% of the outlet pressure, a single-stage pump, or the first stage pump of a multi-stage pump can be fitted with an impeller shaft seal. The impeller's shaft seal has the advantage of no mud dilution, no water, and good sealing properties. This type of seal is suitable when mud cannot be diluted.
Thirdly, mechanical seals are typically used in environments requiring high sealing specifications. Especially in the chemical and food industries, sealing is important since rated components should not enter the pump body. The downside is that they are costly and difficult to maintain.
The two primary parameters of mud pump performance are flow rate and pressure.
The displacement is calculated as the number of litres discharged every minute. It depends on the drill hole diameter and the flushing liquid's required speed. The larger the drill diameter, the greater the displacement required. The flushing liquid should be pumped upwards and backwards to wash out rock debris on the drill bit and ensure it is transported reliably to the surface. A drilling speed of 0.4 to 1.0 m/min is common for geological drilling.
The mud pump's pressure depends on the drill hole depth, the resistance of the flushing liquid through a channel, and the flushing liquid's properties. The deeper the drill hole, the greater the pipe's resistance, and the higher the required pressure.
As the drill hole diameter and depth change, the pump's displacement needs adjustment. The pump mechanism should have a variable speed box or hydraulic motor to adjust its speed and change the displacement.
To accurately understand the pump's pressure and displacement changes, a flow meter and pressure gauge should be installed on the mud pump, and the drilling operator informed of the pump's running and rotating status at all times. Pressure changes can be employed to determine the wellbore's normal state and prevent wellbore accidents.