Project Background and Requirements
A large chemical enterprise's reactor temperature monitoring project required simultaneous monitoring of temperature at 6 different heights within a single reactor to precisely control the reaction process. Traditional single-point thermometers cannot meet the demand for multi-point synchronous measurement, and wiring is complex with high maintenance costs.
The customer required the multi-point thermometer to have high precision, fast response, and corrosion resistance, and to be able to connect to the existing DCS system. After on-site investigation, the project team determined a customized multi-point thermometer solution.
Key Points for Multi-Point Thermometer Selection
Comparison of Key Parameters
| Parameter | Option A (Sheathed PT100) | Option B (Thermocouple) | Option C (Digital Sensor) |
|---|---|---|---|
| Accuracy | ±0.1℃ | ±1.5℃ | ±0.5℃ |
| Response Time | ≤10s | ≤5s | ≤15s |
| Corrosion Resistance | Excellent (316L sheath) | Moderate (requires protective sleeve) | Good (PTFE coating) |
| Wiring Complexity | Moderate (three-wire) | High (compensation wire) | Low (bus) |
Considering accuracy, corrosion resistance, and DCS compatibility comprehensively, Option A (sheathed PT100 multi-point thermometer) was finally selected.
Implementation Steps
Installation and Commissioning Process
- On-site Surveying: Determine the height and insertion depth of each temperature measurement point, and customize flange dimensions.
- Sensor Assembly: Weld 6 PT100 sheathed elements at intervals within a unified protective sheath, and fill with thermal conductive silicone grease.
- Installation and Fixation: Vertically insert the multi-point thermometer into the reactor through the flange, ensuring each measurement point is at the target position.
- Wiring and Configuration: Connect to the temperature transmitter using a three-wire connection, and configure the range and alarm values in the DCS.
- Calibration and Verification: Perform three-point calibration for each measurement point using a dry block calibrator, with errors all less than ±0.2℃.
Project Results and Benefits
- Improved Temperature Measurement Efficiency: Single-point inspection time reduced from 15 minutes to 2 minutes, achieving real-time multi-point monitoring.
- Enhanced Reliability: The sheathed structure withstands 16MPa pressure and has operated continuously for 12 months without failure.
- Cost Savings: Compared to 6 single-point thermometers, installation materials and wiring costs are saved by approximately 35%.
- Data Integration: All temperature signals are directly connected to the DCS and participate in interlock control, improving reaction safety.
This project verified the applicability of multi-point thermometers in complex industrial environments, providing a reliable temperature measurement solution for similar reactors, storage tanks, pipelines, and other scenarios.
Selection and Procurement Recommendations
- Clarify the number of temperature measurement points, spacing, and insertion depth, and prioritize customized sheathed structures.
- Select sheath material (such as 316L, Hastelloy) based on medium corrosiveness.
- Confirm that the output signal type (RTD, 4-20mA, HART, etc.) matches the control system.
- Require the supplier to provide single-point calibration reports and third-party metrology certification.
For more multi-point thermometer application cases or technical parameters, please contact us for detailed information.