The continuous metering system (CMS) liquid-additive metering system (Figure 1 and Table 1) is used to meter all types of liquid additives. With correct calibration and maintenance, the CMS system accurately meters both low-viscosity and high-viscosity additives. This additive system can be retrofitted to operate with conventional recirculating mixer (RCM®) systems on any cementing skid. It delivers liquid additives to the mixing water at a rate proportionate to the mixing rate.
Unlike previous additive systems, the CMS system does not introduce additives into the displacement tank. The CMS system continuously injects liquid additives into the suction side of the mixing pump that supplies water to the mixer. The liquid additives and mixing water are well mixed by the impeller of the mixing pump before the water enters the mixer.
The CMS system has the following major components:
- Progressive cavity liquid-additive pumps
- Three-phase electric motor
- FVNR motor starter
- Unipro II™ controller
- D1TX proportional valves
- 20-gal hydraulic tank
- Load-sense hydraulic pump
- Commercial shearing gear pump
- hydraulic storage, filtration, and cooling systems
The advantages of the CMS system include the following:
- Liquid additives are continuously injected into the mix water and uniformly mixed with either salt water or fresh water.
- The system eliminates the need for air-powered lightning mixers within the displacement tank.
- The system incorporates a place for mounting HalTank™ containers with the additive system, reducing the amount of required rig floor space.
- The system uses smaller displacement pumps and smaller motors, reducing overall unit costs.
- The system can power agitators for adequate agitation of liquid additives before and during the job.
- 80-ft3 Steady Flow-Separator