Monthly Archives: August 2012

features of Mud cleaning equipment

  • Mud cleaning equipment mainly is suitable for taking mud solid wall and large diameter pile foundation of circulation drilling process in the modern foundation engineering construction and diaphragm wall engineering.
  • The fully cleaning of the drilling mud is favorable to control the performance index of mud, reduce the fault of jamming of a drilling tool and increase the quality of the well drilling.
  • The effective separation of the soil slag is benefit to increase the work efficiency of  pore-forming
  • The recircle usage of the mud is favorable for save the material of mud and working cost.
  • 4.The closed cycle way of the mud and lower slag charge moisture content is favorable for the
  • reduce of environmental pollution.
  • The unclear mud pumped from the bottom of the well by the reverse circulation sand pump transfers to the mud cleaning devices through the main admission tube, then the solid phases with diameter of 3mm will be separated by the shale shaker. The mud after treated by the shale shaker will flow into the storage tank of mud cleaning equipment, then the slurry pump pumps the mud form the tank. The mud jets into the swirler through the inlet hole. By the separation of swirler, the superfine sediments will be discharged from the grit mouth under the swirler, then fall into the fine screen. After separated by the fine screen, the dry solid phases have been separated from the mud, and the mud treated by the swirler will return to the storage tank. The clean drilling mud flows from the overflow tube of swirler to the middle storage box, then transfer to the well hole through the main outlet pipe.
  • There is a recoil branch at the exit of slurry pump to connect with the storage tank. The recoil branch
    can agitate the solid phases precipitated in the tank to avoid deposition of solid phase and overflow of the mud.
    In the circle process of mud, use a level buoy between the middle storage box and storage tank to keep liquid level constant in storage tank of the mud cleaning equipment. When the output of mud is larger than the
    supply, the level buoy will decrease along with the liquid level, at this time, the mud in the middle storage box will
    be delivered into the storage tank through the slurry pipe, the liquid level will increase to the original situation.
  • And vice versa.
  • When higher quality mud is required, workers can reduce the total volume of mud and repeat the separation process in swirler to match the requirements.

Differenct effect of shaker screen with different vibration modes (B)

C. Translation linear vibration mode

The shale shaker with linear moving of each point on the screen box, its screen can be installed horizontally. The screen has a high speed on transporting the solid phase, there will be no problem of accumulation of drilling particles. So long as a appropriate vibration direction, the handling capacity can be increased. This method is widely used overseas, and this kind of mode is preferable.

But if the angle of vibration direction is too large (the angle means the included angle between linear vibration direction and horizontal plane),  thenormal acceleration of the shale shaker will be rised, the drilling particles will be thrown too high and easy to smash when slump to the screen to increase the rate of passing screen mesh.

Moreover, because of the linear motion of the linear screen, acceleration vector will affect on one direction only,  there is some chuck blind area for the solid particles block in the mesh (the chuck blind area means the directions where the acceleration vector is 0), it is hard to throw or clean the particles block in the meshes. Therefore, the meshes are easy to be blocked and this is harmful for drilling mud cleaning.

D. Translation elliptic vibration mode

The translation elliptic shale shaker has combined the advantages of circular shale shaker and linear shale shaker.  Because the major axis of the ellipse inclines in the outlet direction of the shale shaker,  the moving laws of each point are the same. The transverse amplitude is larger than vertical amplitude, the major axis of the ellipse is the component of cleaning drilling particles strongly, and the short axis is the component of prompting passing through the screen, so, when separate the solid and liquid, this mode can increase the transportation speed and decrease the residence time of solid phase on the shaker screen, therefore to decrease the rate of passing meshes. Just because of the component of short axis direciton prompts the critical particles jumping out or passing through the meshes, the danger of meshes block has been largely controlled.

In consulsion, when the frequency of the shale shaker is fixed, it is very reasonable to match an appropriate transverse amplitude and a larger normal amplitude for the drilling mud shale shaker. According to this requirement, the common single axis shale shaker is the worst. Though the circlular shale shaker has been improved, because of the large chuck angle, it has already been weed out.  The self-synchronizing translation linear shale shaker and self-synchronizing translation elliptic shale shaker are the mainstream in the current petroleum drilling industry based on their double motor self synchronization technology.

The information comes from Tangshan Dachuan Machinery Co., Ltd.

 

Differenct effect of shaker screen with different vibration modes (A)

The requirement for shale shaker by the drilling technical is to recover the drilling fluid as much as possible, and clean the harmful solid phase as much as possible. Therefore, it requires:

a. In order to increase the processing quality, recover the drilling fluid, the solid phase on the screen should be discharged ASAP.

b. To decrease the wear degree of screen, it is better that the solid particles do not do  sliding motion.

c. The stuck critical particles should be easy to pass the mesh or  jump out  of screen.

The vibration mode of shaker screen

A. Traditional elliptical vibration mode

Because there is a vibration exciter on the right above of barycenter of screen box, and all the trajectory of each points of the inlet and outlet is ellipse, but the long shaft extension cords intersect on the shaker screen.  Because the transverse amplitude is larger than normal amplitude and the specific value of these two amplitude is larger than the circular vibration mode’s,  the average transport speed is higher than circular shale shaker.  The sand grains’ transportation at the  entrance of this shaker is good, but, because the long axis of ellipse trajectory at the outlet hole inclines into the shaker, the moving speed of drilling particles become lower and it is difficult for the particles to jump out of screen, even accumulation of drilling particles appears.  The accumulation of drilling particles increases the chance of passing the mesh and quantity of solid phase in drilling fluid. If screen extended, backflow would appear, and would affect the disposing of drilling fluid. Therefore, it requires a inclination angle of the shaker screen to discharge the sand via gravity to avoid chucking backward. Though the inclination of screen box has improved the moving performance of the sand particles, but the thruput of drilling fluid also decreased, this is the main disadvantage of non translational elliptical vibrating shale shaker.

B.Circular vibration mode

The vibration is installed on the barycenter of screen box, the resultant force of vibration force and spring reaction will pass the barycenter, the vibration mode of each point on the screen box is approximate circle. The transverse amplitude is equal to normal amplitude. The shaker screen can be installed horizontally, and there will be no accumulation of drilling particles, the disposing thruput will be larger. But the chucks angle is the function of acceleration of screen type. When the normal velocity is 3-6times of gravity velocity, the chucks angle of solid phase will be 70-80 degree.  The chucks angle makes a large whereabouts inertia, smashing easily and high speed of sand transportation, the through sieve rate is be increased accordingly, which is disadvantageous for the cleaning of drillign fluid.

More infos pls have a look of our website: Tangshan Dachuan Machinery Co., Ltd.