Applications of Temperature Sensors in Screw Pumps

Screw pumps are positive displacement rotary pumps which transfer fluid through volume changes in screw meshing spaces, widely used in petrochemical, oil & gas, marine fuel, food, pharmaceutical and environmental applications.

What is key difference of centrifugal pumps and screw pumps

Temperature sensor focus on bearing and media temperature monitoring of centrifugal pumps. But for screw pumps, temperature sensor will additionally monitor meshing zone temperature which is the most dangerous hotspot in positive displacement pumps.

What is critical temperature sensor monitoring points of screw pumps

1.Temperature Sensor Monitoring Screw Meshing Zone Temperature

This is a temperature sensor monitoring point unique to screw pumps. The purpose of temperature sensor monitoring is to prevent metal to metal contact at meshing surfaces to avoid causing seizure.

The selection of temperature sensor could be miniature Pt100, stainless armored. But the installation challenge is that temperature sensor cannot insert directly into meshing zone. It should embed at nearest pump body wall. Temperature sensors will be placed 2 to 3 monitoring points along meshing line, using max value for protection logic
  
2.Temperature Sensor Monitoring Screw Shaft Temperature

The purpose of temperature sensor monitoring is to control thermal expansion to prevent meshing clearance loss.

The selection of temperature sensor could be thin-film Pt100 surface mount with stainless clamp.

3.Temperature Sensor Monitoring Journal Bearing Temperature

Screw pumps typically use journal bearings for both drive and driven screws. The temperature sensor will monitor bearing temperature which is the most common damage indicator.

The selection of temperature sensor could be embedded Pt100, M6 thread.

4.Temperature Sensor Monitoring Thrust Bearing Temperature

Screw pumps generate significant axial force under high viscosity or high differential pressure conditions, thrust bearings carry heavy load. The temperature sensor will monitor thrust collar working side shell back

The selection of temperature sensor could be embedded Pt100, 2-3mm from thrust surface.

5.Temperature Sensor Monitoring Mechanical Seal Temperature

The purpose of temperature sensor monitoring is to prevent dry friction at seal faces, detecting if flush fluid loss.

The selection of temperature sensor could be Pt100 surface mount on seal gland exterior.

High viscosity service needs heated seal chamber while temperature sensors monitoring doubles as heating control feedback.

6.Temperature Sensor Monitoring Pump Body Temperature

The purpose of temperature sensor monitoring is to monitor media temperature distribution, evaluating insulation or heating effect.

High viscosity media like bitumen, heavy oil requires pump body heating, temperature sensor can interlock heating system.

The selection of temperature sensor could be Pt100 surface mount with insulation penetration thermowell.

7.Temperature Sensor Monitoring Medium Inlet & Outlet Temperature

The purpose of temperature sensor monitoring inlet is to verify medium viscosity within allowable range. The purpose of temperature sensor monitoring outlet is to monitor medium temperature rise, below 15°C rise is normal for positive displacement pumps. If temperature rise above 15°C, it indicates increased internal slip or clearance wear.

The selection of temperature sensor could be immersion Pt100 with flange mounted thermowell.

8.Temperature Sensor Monitoring Lubricating Oil Temperature

The purpose of temperature sensor monitoring gearbox or oil bath is to monitor lubrication condition.

The selection of temperature sensor could be immersion Pt100, one for oil bath, one for supply and one for return.

Summary

The deep value of screw pump temperature sensors lies not in single point measurement but in a four-in-one system including transient protection, stator smart algorithm,  triangular fusion diagnostics and SIL functional safety, which enable most component suppliers to upgrade to system solution providers.