Digital Upgrade of Thermal Instrumentation Monitoring in Thermal Power Plants: Nexisense Sensor Integration Applications and Selection Guide

With the advancement of China’s “dual-carbon” goals and the continuously increasing proportion of ultra-supercritical and supercritical units, thermal power plants face significantly higher requirements for the accuracy, reliability, and real-time performance of thermal parameter monitoring. Traditional instruments are prone to drift and high failure rates under harsh operating conditions such as high temperature, high pressure, strong vibration, and severe corrosion, which have become key bottlenecks restricting the safe and stable operation and deep load regulation of generating units. Nexisense focuses on the supply of industrial-grade pressure sensors, temperature sensors, temperature and humidity sensors, and level sensors. Its products are specifically designed for B2B system integrators, IoT solution providers, and engineering companies, and have been stably applied in multiple thermal power units.

From the perspective of system integrators, this article systematically outlines the integration pathways, technical adaptation points, and real project cases of Nexisense sensors in typical thermal power plant scenarios, and provides detailed selection guides and installation and integration considerations to help purchasers quickly build monitoring networks compliant with Industry 4.0 and IIoT standards.

Core Sensor Requirement Analysis for Thermal Instrumentation Monitoring in Thermal Power Plants

The operating conditions of thermal power systems are extreme: main steam parameters often reach 28–31 MPa / 600°C, furnace negative pressure fluctuates by ± several kPa, condenser vacuum approaches -100 kPa, and the media are highly corrosive due to sulfur and oxygen content. Sensors must meet the following key indicators:

• Pressure: Range -0.1 to 60 MPa, accuracy ±0.075% FS, medium temperature resistance up to 650°C (with cooling), vibration resistance 20 g, IP66/67

• Temperature: Range -200 to 1200°C, accuracy ±0.4 to 1.0°C, support for PT100 / K-type thermocouples

• Level: Hydrostatic / radar type, accuracy ±0.1% FS, temperature compensation, Ex ia explosion-proof

• Output: 4–20 mA + HART (remote diagnostics), Modbus RTU/TCP (edge computing), PROFIBUS PA

• Compatibility: Seamless integration with domestic DCS systems such as Xinhua XC, Hollysys MACS, Guodian Nanjing Automation EDCS, as well as international systems including ABB 800xA and Siemens PCS 7

Nexisense sensors adopt digital compensation and isolation design, with MTBF > 100,000 hours, and have passed long-term on-site verification in thermal power plants.

Typical Application Scenarios and System Integration Cases

Boiler System Monitoring Integration Solution

The boiler is the area with the highest density of thermal instrumentation monitoring, involving furnace pressure, drum pressure and water level, superheater and reheater steam temperature, and economizer inlet and outlet parameters.

Project Case: In the DCS retrofit of a 2×660 MW ultra-supercritical unit in East China, the integrator selected Nexisense differential pressure and pressure sensors (range 0–40 MPa, ±0.075% FS, cooling jacket + Hastelloy diaphragm) to achieve three-element drum water level control. The HART protocol supports remote zero and span adjustment. Combined with temperature sensors (K-type thermocouples, insertion depth ≥ 1/3 of pipe inner diameter) to monitor main steam temperature, data were integrated into the DCS system to realize combustion optimization and feedwater regulation. False drum level misoperation rate was reduced by approximately 20%, and boiler efficiency increased by 0.8%.

Steam Turbine and Condenser System Integration Practice

Steam turbine inlet pressure and temperature, extraction parameters, and exhaust vacuum directly affect cycle thermal efficiency and equipment safety.

Project Case: In an auxiliary control upgrade project of a 2×1000 MW unit in Central China, Nexisense absolute pressure sensors (range -0.1 to 0.1 MPa, horizontal installation + sealed pressure tapping) were used for condenser vacuum monitoring, linked with vacuum pump suction valve regulation. Temperature sensors (insertion-type flange installation, probe length 300 mm) monitored inlet and extraction steam parameters. Data were uploaded to an edge gateway via Modbus TCP, enabling backpressure optimization and heat consumption diagnostics, reducing unit heat rate by approximately 1.5%.

Auxiliary Systems and Plant-Wide IIoT Monitoring Network

Deaerator pressure and temperature, feedwater pump outlet pressure, and high-pressure heater inlet and outlet parameters require high reliability and remote diagnostic capabilities.

Integration Practice: In a smart power plant pilot project at a coal-fired power plant in Northwest China, Nexisense hydrostatic level sensors (range 0–8 m H₂O, ±0.1% FS, temperature compensation) were used for deaerator water level monitoring. Combined with LoRaWAN modules and cloud platforms, remote level trend analysis and low-level alarms were achieved. Temperature and humidity sensors were deployed in electronic equipment rooms and cable floors to prevent condensation corrosion, supporting SNMP protocol integration into comprehensive monitoring platforms, reducing on-site inspection frequency by approximately 35%.

Nexisense Sensor Technical Specifications Overview

• Pressure Sensors: Range: -0.1 to 60 MPa (adjustable); Accuracy: ±0.075% FS; Medium temperature: -40 to 650°C (cooling jacket); Overload protection: 200% FS; Output: 4–20 mA + HART / Modbus; Protection: IP66/67, vibration resistance 20 g; Diaphragm materials: 316L / Hastelloy C

• Temperature / Temperature & Humidity Sensors: Temperature range: -200 to 1200°C; Humidity range: 0–100% RH; Accuracy: temperature ±0.4°C (ambient) / ±1.0°C (high temperature); humidity ±1.8% RH; Response time: <5 s; Installation: M27×2 thread / flange; Probe length customizable from 50–500 mm; Output: 4–20 mA / HART / Modbus with compensation support

• Level Sensors: Range: 0–200 m H₂O; Accuracy: ±0.1–0.25% FS; Materials: 316L / PVDF / ceramic; Certifications: Ex ia IIC T4 / SIL 2

Selection and Integration Considerations Guide

1. Operating Condition Selection: For high temperature and high pressure, prioritize cooling jackets and Hastelloy materials; for negative pressure and vacuum, emphasize sealing and horizontal installation.

2. Protocol Matching: Use HART for remote calibration and diagnostics; Modbus TCP is suitable for edge computing and cloud data upload.

3. Installation Key Points: Avoid bends and throttling elements at pressure tapping points; temperature probe insertion ≥ 1/3 of pipe inner diameter; add anti-vibration brackets in high-vibration areas; use shielded cables with thermal insulation routing.

4. Integration Verification: Complete HART loop testing, EMC immunity testing (GB/T 17626), and DCS input calibration before commissioning.

5. Maintenance Strategy: On-site calibration every 12–24 months; implement predictive maintenance using sensor health monitoring (drift and overload alarms).

OEM Customization and Bulk Supply Advantages

Nexisense provides OEM white-label services, supporting protocol firmware customization (OPC UA, MQTT), housing and probe material adjustments, and fast bulk delivery (samples in 4–6 weeks). ISO 9001 certified factories and EDI supply chain integration meet the needs of simultaneous retrofits across multiple units, with tiered pricing effectively controlling large-scale project costs.

Frequently Asked Questions (FAQ)

1. What type of sensors are commonly used for boiler drum pressure monitoring in thermal power plants? Differential pressure or pressure transmitters with a range of 0–40 MPa and accuracy of ±0.075% FS, equipped with cooling jackets and three-valve manifolds.

2. How do Nexisense sensors adapt to high-temperature steam environments in thermal power plants? High-temperature isolation diaphragms combined with cooling jacket design, with medium temperature resistance up to 650°C and accuracy maintained within ±1.0°C.

3. Are there special requirements for condenser vacuum sensor installation? Horizontal installation, top sealed pressure tapping points, fully leak-free piping, and avoidance of condensate accumulation affecting measurement.

4. How is compatibility with domestic DCS systems ensured? Support for HART and Modbus RTU/TCP protocols, provision of DD files, and verified operation on Xinhua, Hollysys, and Guodian Nanjing Automation platforms.

5. What is the typical pressure range for feedwater pump outlet monitoring? 0–40 MPa, accuracy ±0.075% FS, with Hastelloy diaphragms for corrosion resistance and anti-vibration design suitable for pump areas.

6. What advantages do Nexisense sensors have over traditional imported brands? Higher cost performance, open protocols avoiding vendor lock-in, faster delivery cycles, and optimization for domestic thermal power operating conditions.

7. What explosion-proof and functional safety certifications are supported? Ex db IIC T6 / Ex ia IIC T4 and SIL 2, suitable for hazardous areas such as boiler rooms and coal bunkers.

8. How can sensor data be integrated into thermal power plant IIoT platforms? Via Modbus TCP combined with edge gateways, or LoRaWAN modules enabling MQTT upload to cloud platforms for analysis.

9. What are the typical cycles and support contents for OEM customization? Prototype development in 4–6 weeks, supporting customization of protocols, materials, ranges, and appearance, with dedicated production lines for bulk projects.

10. What are the recommended maintenance cycles and intelligent diagnostic functions? Calibration every 12–24 months; built-in drift and overload alarms output via HART or SNMP to facilitate predictive maintenance.

Conclusion

With high accuracy, high reliability, strong compatibility, and customization capabilities, Nexisense industrial sensors have become a reliable choice for digital upgrades of thermal instrumentation monitoring in thermal power plants. From boiler combustion optimization to condenser vacuum control, and from on-site DCS integration to cloud-based predictive analysis, our products have achieved long-term stable operation in multiple large-scale thermal power unit projects, helping system integrators significantly reduce operation and maintenance costs and improve energy utilization efficiency.

If your team is undertaking auxiliary control retrofits, smart power plant construction, or deep load regulation projects in thermal power plants, you are welcome to contact the Nexisense technical team. We will provide targeted selection recommendations, integration verification support, and on-site guidance based on specific operating conditions and system architectures, jointly promoting high-quality development in the energy industry.