Power Industry Gas Detection Solutions

The power industry is a backbone of the national economy. Thermal power plants, as main contributors, involve high temperature, high pressure, chemical reactions, and electrical equipment, where gas risks are prevalent. Boiler combustion produces carbon monoxide (CO), carbon dioxide (CO₂), hydrogen sulfide (H₂S), and other by-products. Flue gas desulfurization and denitrification systems use large amounts of liquid ammonia (NH₃), where leaks may cause poisoning or explosions. High-voltage switchgear widely uses sulfur hexafluoride (SF₆) as insulation and arc-quenching medium; leaks threaten personnel safety and have extremely high global warming potential (GWP ~22,800× CO₂), thus strictly regulated. Additionally, combustible gases and nitrogen oxides (NO, NO₂) may accumulate in certain areas.

According to the National Energy Administration's "Twenty-Five Key Requirements for Preventing Power Production Accidents" and industry standards, power plants must be equipped with ammonia leak detectors (covering ammonia zones, remote data transmission, local alarms, and sprinkler linkage) and SF₆ leak alarm systems (GIS room installation, humidity and micro-water detection) to ensure real-time monitoring of gas concentrations in personnel-dense areas. Nexisense provides complete solutions from fixed online monitoring to portable inspection, helping power plants build multi-layered gas safety protection, achieve early hazard detection, risk control, and accident prevention.

Gas Risk Analysis in Power Production

Thermal power plant gas risks are dispersed and diverse. Boiler rooms and flue systems produce CO (asphyxiant, MAC 20mg/m³) and H₂S (highly toxic, MAC 10mg/m³). Ammonia zones pose high leak risks at storage and pipeline valves; ammonia is highly irritating, and concentrations above MAC 20mg/m³ can cause respiratory damage or death. SF₆ leaks in GIS rooms can cause low-level oxygen deficiency (SF₆ density ~5× air) and produce toxic fluorinated by-products.

Other risks include combustible gas accumulation in coal yards or boiler areas and excess nitrogen oxide emissions. Leak causes include aging equipment, seal failure, operational errors, or insufficient maintenance. Incident cases show ammonia leaks caused poisoning, and SF₆ leaks induced GIS room oxygen deficiency. These risks threaten worker health, cause equipment downtime, environmental fines, and reputational damage. Real-time monitoring enables linkage with ventilation, sprinklers, or cutoff systems, significantly reducing accident probability.

Advantages of Nexisense Online Gas Detectors

The Nexisense SGA-500 series online gas concentration detectors use original imported sensors, secondary calibration via infrared analyzers and calibration devices, with built-in temperature and humidity compensation and signal amplification circuits to ensure stable accuracy in high-humidity, high-dust, high-temperature power plant environments. Devices operate on 24V DC, plug-and-play, with no reagents or complex setup required.

For ammonia zones, SGA-500 detectors provide 2-wire or 3-wire 4-20mA output, compatible with PLC and DCS systems, supporting custom ranges (common 0-100ppm / 0-200ppm) and alarm points (level 1: 25ppm, level 2: 50ppm). SF₆ modules support customizable ranges (0-1000ppm / 0-2000ppm), sampling modes (diffusion/pump), outputs (4-20mA / RS485 Modbus), data storage, and smart calibration, meeting DL/T 595-2016 "SF₆ Electrical Equipment Gas Supervision Guidelines".

Response time<30s, accuracy ±3% FS, explosion-proof grade Ex d IIC T6 Gb, IP65 protection, suitable for ammonia zones, GIS rooms, boiler rooms. In practice, a plant implementing ammonia detection reduced leak response time to minutes, avoiding potential poisoning incidents.

Sensor Selection and Technical Highlights

Ammonia uses electrochemical sensors with high selectivity and interference resistance; SF₆ uses infrared NDIR sensors for anti-poisoning and long life; CO/H₂S uses high-precision electrochemical or catalytic sensors. Full-range temperature and humidity compensation covers -20°C to +60°C, 95% RH environments. Remote calibration is supported to reduce maintenance complexity.

Alarm Controller Integration and System Management

The SGA-500 series integrates with the SGA-800 alarm controller to build a distributed gas alarm system. The controller supports line/bus mode, expandable to 64 points, centralized power supply, signal acquisition, LCD display of real-time concentrations. Over-limit triggers graded audible/visual alarms, relay outputs link to fans, sprinklers, cutoff valves, or fire systems.

Typical ammonia zone linkage: 25ppm triggers local ventilation + alarm, 50ppm triggers full-zone sprinklers + emergency broadcast. GIS room SF₆ alarm triggers exhaust + access restriction. Central control room can view all data; Modbus RTU/TCP supports remote SCADA integration for digital management.

Linkage Scenarios and Maintenance Recommendations

Level 1 alarms trigger inspection alerts; level 2 activates emergency plans. Controllers calibrated quarterly to ensure relay reliability. System integration improves response efficiency and reduces human delay.

Portable and Modular Supplementary Monitoring

Fixed monitoring covers core areas; portable inspection complements dynamic checks. Nexisense SGA-600 portable detectors are small, single-handed operation, supporting diffusion/pump/probe sampling, suitable for ammonia pipelines, GIS lower levels, boiler dead zones. Real-time concentration display, automatic alarms, 8-12h battery, data storage for traceability.

Additionally, SGA-700 smart sensor modules, SGA-100 monitoring modules, and SGA-900 pretreatment systems support integration retrofits or harsh environments (e.g., high-dust flues) with customizable solutions.

Practical Inspection Tips

Daily inspection focus: ammonia zone valves, GIS room bottom. Bump tests ensure sensor validity; export data for monthly reporting.

Implementation Strategy for Power Plant Gas Detection

Conduct risk assessment before deployment, identifying ammonia zones, GIS rooms, boiler rooms. Prioritize fixed monitoring + controller coverage, portable inspection supplements dynamic checks. Staff training covers gas hazards, alarm response, PPE usage. Regular maintenance (quarterly calibration, annual full inspection) ensures system availability >99%. Complies with "Twenty-Five Key Requirements" and DL/T standards, supporting standardized safe power production.

Long-term, investments reduce accident probability, downtime losses, improve environmental performance, and provide data foundation for digital transformation.

FAQ

1. How to select output and range for ammonia detectors? Choose 2-wire (simple, low-cost) or 3-wire (higher precision, interference resistance) 4-20mA based on PLC/DCS interface. Typical ranges 0-100ppm (covers MAC 20mg/m³≈30ppm), alarm points level 1:25ppm (ventilation), level 2:50ppm (sprinklers). Nexisense supports custom ranges for seamless integration.

2. SF₆ detection in GIS room: installation and monitoring points? SF₆ is dense; leaks accumulate low. Install 0.3-0.5m above floor, downwind, covering flanges and valves. Monitor concentration (0-1000ppm) and micro-water per DL/T 595. SGA-500 supports infrared sensor + smart calibration, linked to exhaust and access control.

3. Portable detector runtime and sampling recommendations? SGA-600 diffusion: 10-12h, pump: 8h, USB charging. Use pump + probe for ammonia pipelines or GIS lower levels. Charge after daily inspection, low battery warning, 1000 data points. Bump test before use, supports multi-shift operation.

4. Alarm controller linkage in ammonia zones and GIS rooms? Relays + Modbus: ammonia 25ppm triggers ventilation + local alarm, 50ppm cuts ammonia pump + full-zone sprinklers; SF₆ above 1000ppm triggers forced exhaust + audiovisual alarms + access restriction. SGA-800 supports zoned management, graded delay to prevent false alarms, expandable to 64 points for central dispatch.

5. Integration with existing SCADA or DCS? Supports 4-20mA/RS485 Modbus RTU/TCP via gateway/OPC server for real-time curves and alarm logs. Data for environmental reporting, predictive maintenance. Network isolation/encryption recommended. Many plants integrate monitoring into digital operations to improve traceability and response.

6. Protection and maintenance in high-temp, high-dust environments? IP65+, Ex d, corrosion-resistant housing. Monthly filter cleaning, quarterly bump test + 0/span calibration, sensor life 2-3 years. High dust: calibrate monthly, check seals to prevent condensation. Logging ensures ±5% accuracy.

7. Emergency response after gas leak? Use SGA-600 to map concentrations, mark danger zones (ammonia>25ppm/SF₆>1000ppm), activate ventilation/sprinklers. Wear positive pressure respirator. Export logs (peak, duration, trigger) for root cause analysis. USB/Bluetooth report supports accident investigation and improvements.

8. ROI evaluation for Nexisense solution? Initial cost (detector + controller + installation) vs potential benefits: prevent ammonia poisoning/downtime (hundreds of thousands to millions per incident), avoid SF₆ fines, reduce insurance, optimize ventilation and energy 5-15%. ROI 1-2 years, hazard reduction 30-50%. Include annual sensor replacement (10-15%) for long-term evaluation.

Conclusion

Power industry gas risks are complex but can be effectively managed with scientific monitoring. Nexisense SGA-500 online detectors, SGA-800 controllers, and SGA-600 portable units form a closed-loop solution covering ammonia zones, GIS rooms, and boiler rooms, ensuring compliance with NEA requirements and industry standards. Early deployment protects personnel, equipment stability, environmental compliance, and sustainable development. Plants are advised to customize configuration based on on-site assessment to build a reliable gas safety baseline.