Frequent failures of Chemical Injection (CI) skid motors

[krisys]

One of the remote oil fields we have many Chemical Injection (CI) skids installed at various locations. These CI skids are installed recently (between 1 to 3 years old). Each CI Skid is having single pump and intended to be operated continuously.

The pumps are driven by 24V DC Permanent magnet Ex ”d” motors (motor rating is 0.18 kW). We are experiencing pre-mature failures of these motors, primarily due to the requirement of frequent maintenance (requires quarterly inspection/ maintenance/ replacement of the carbon brushes).

One of the consultants have suggested to replace the existing DC motors with inverted type motors. The inverted motor is essentially an AC induction motor with embedded inverter in the volume of terminal box. Hence there is a possibility of in-situ replacement.

Has anyone in this forum having any experience with this type of motor? How reliable these motors are for the prolonged trouble free operation.

Sharing of any such experiences is well appreciated.

 

[ScottyUK]

A conventional motor and separate inverter will be easier to support - both are commodity items and common as dirt.

Some of the integrated units are decent - the Siemens ones of a few years ago certainly were - but I'm not sure they are sufficiently well-protected for long term use outdoors. Are these pumps in an enclosure, or in the open?

Edit: not sure you'll find an integrated motor-inverter in an Ex 'd' enclosure - the ones I'm familiar with were IP55 but not not certified for hazardous duty.

 

[krisys]

These motors are to be installed in the Chemical Injection (CI) skids of offshore Well Head Towers. These are truly outdoor installations subjected to very harsh environment.

We have identified a vendor from France called "EXPOW". Anyone has experience with this vendor?

 

[SilverfoxUK]

for injection at this very low rate have you considered moving from motors to a solenoid operated metering pump. You would need to check on ATEX etc for your particular environment. 2 of these metering pumps would give redundancy to your remote application. Well suited to a closed loop 4-20mA control.

 

[krisys]

Silverfox;

The location is an unmanned, oil well head tower in the middle of the sea.
Earlier, the pumps were operating with the produced gas at high pressure. The gas pressure used to drive this CI pump. But the gas used to drive the pump was let to the atmosphere.

Due to the environmental issues this has been now changed to electrical motor driven pumps.