Chimney & Exhaust Stack Industry Gas Detection Solutions: Nexisense Enabling Precise Fixed Source Emission Monitoring

Chimneys and exhaust stacks serve as the primary discharge channels for fixed pollution sources such as industrial enterprises, thermal power plants, boilers, and incinerators. The pollutants released directly affect regional air quality and public health. Common emission gases include sulfur dioxide (SO₂), nitrogen oxides (NOx, including NO and NO₂), carbon monoxide (CO), ozone (O₃), hydrogen chloride (HCl), hydrogen cyanide (HCN), ammonia (NH₃), hydrogen sulfide (H₂S), formaldehyde, hydrogen fluoride (HF), chlorine (Cl₂), as well as particulate matter PM2.5 and PM10. If these pollutants exceed emission limits, they not only violate regulations such as the “Integrated Emission Standard of Air Pollutants” (GB 16297), but may also cause environmental problems such as acid rain and photochemical smog.

With increasingly strict environmental supervision, Continuous Emission Monitoring Systems (CEMS) for fixed sources have become mandatory. Real-time and accurate flue gas monitoring helps enterprises optimize combustion processes, control desulfurization and denitrification efficiency, and ensure direct data transmission to environmental platforms, avoiding fines and production shutdown risks. Nexisense provides a full-chain solution from air quality micro stations to full-parameter online flue gas analysis, enabling efficient and reliable exhaust stack gas monitoring.

Core Requirements and Challenges of Chimney & Exhaust Stack Monitoring

Chimney emission monitoring faces multiple challenges such as high temperature, high humidity, high dust concentration, and strong corrosiveness:

• High-temperature flue gas: exhaust temperatures often reach 100–800°C, requiring high-temperature resistant sampling.

• Complex components: multiple gases coexist with significant interference, requiring highly selective sensors.

• Data compliance: must support HJ212 protocol, minute-level upload, and historical traceability.

• Flexible deployment: grid-based monitoring requires miniaturized and low-power devices.

Effective monitoring not only ensures compliance but also feeds back process status, such as NOx exceedance indicating combustion adjustment, or SO₂ anomalies suggesting desulfurizer dosing optimization.

How to Select Dedicated Chimney Gas Monitoring Equipment?

Key selection points include:

• Target parameters: conventional NOx (NO+NO₂), SO₂, CO, O₂, with optional PM, NH₃, etc.

• Sampling method: in-situ insertion probe or extractive pre-treatment system.

• Accuracy and stability: temperature and humidity compensation, low zero drift, response time <30s.

• System integration: 4–20mA/RS485 output, HJ212 networking.

• Maintenance convenience: automatic back-blowing, remote diagnostics.

Nexisense Core Product Introduction

For chimney and exhaust stack scenarios, Nexisense has launched multiple mature devices.

Air Quality Monitoring Micro Station — SGA-500 Series

This micro station integrates high-precision intelligent sensor modules, capable of simultaneously monitoring six gases (CO, SO₂, NO₂, O₃, etc.) + two particulates (PM2.5, PM10) + temperature and humidity, wind speed and direction, atmospheric pressure, noise, and other parameters. All data are integrated into a protective enclosure with large-screen real-time display and support for HJ212 protocol direct transmission to environmental platforms.

Advantages:

• User-customized ranges and parameters, suitable for grid-based deployment.

• Low-power design, convenient for solar power supply or remote deployment.

• Waterproof and dustproof housing, suitable for plant boundary or urban air quality monitoring.

Flue Gas Nitrogen Oxides Online Monitoring System — SGA-900 Series

Designed specifically for NOx online analysis in exhaust stacks, equipped with a high-precision sensor module supporting basic monitoring of NO, NO₂, and O₂, expandable to SO₂, CO₂, HCl and forming a six-gas system. Integrated dust and moisture removal filters, vacuum pump, backup power supply, and wireless module ensure continuous stable operation.

Key features:

• High-temperature resistant sampling probe inserted directly into the chimney; extracted flue gas enters the gas chamber after pre-treatment.

• High-definition LCD display of real-time concentration with configurable alarm thresholds.

• Supports multiple protocol outputs for connection to CEMS host or PLC.

High-Temperature Resistant Sampling Probe and Pre-Treatment System

Nexisense provides dedicated high-temperature resistant probes (up to 800°C+), combined with heated tracing lines and anti-clogging filtration to achieve effective flue gas extraction. After dust and moisture removal, the flue gas enters the analyzer, preventing condensation interference and ensuring data accuracy.

Typical CEMS overall architecture schematic, covering sampling, pre-treatment, analysis, and data transmission.

Typical Application Scenarios

• Thermal power plants and industrial boilers: real-time chimney NOx and SO₂ monitoring to optimize denitrification efficiency.

• Municipal and hazardous waste incineration: multi-parameter compliance monitoring of HCl, CO, and particulates.

• Chemical and metallurgical enterprises: monitoring of special gases such as HF, Cl₂ + PM.

• Urban grid monitoring: plant boundary air quality micro stations to assess diffusion impact.

  
  

Frequently Asked Questions (FAQ)

1. What pollutants does the Nexisense SGA-900 series flue gas monitoring system mainly target? Does it support expansion? The basic configuration monitors NO, NO₂, and O₂ related to NOx parameters. It can be expanded to SO₂, CO, CO₂, HCl, HF, NH₃, etc., forming a six-gas + particulate multi-parameter system. Ranges are customized according to emission standards (e.g., 0–2000 mg/m³ NOx), suitable for thermal power and incineration conditions.

2. How is the high-temperature sampling probe installed on the chimney? What are the temperature requirements? The probe is directly welded or flange-mounted to the chimney sampling port, inserted 1/3–2/3 into the flue center. Temperature resistance exceeds 800°C, equipped with heated tracing lines to prevent condensation. Installation must consider flue gas velocity (>5m/s) and negative pressure; professional on-site positioning is recommended to avoid blockage or leakage.

3. How does the system meet HJ212 environmental networking requirements? What is the data upload frequency? Built-in HJ212 protocol module supports minute-level (or 5-minute average) data upload to environmental platforms, including concentration, converted values, and operating parameters (temperature, pressure, flow rate, oxygen content). Features offline caching, automatic retransmission, and instant over-limit alarms to ensure data integrity and traceability.

4. Is the SGA-500 series air quality micro station suitable for grid deployment? How about power supply and protection? Highly suitable for urban/plant boundary grid deployment, integrating six gases + two particulates + six meteorological parameters. Supports solar + battery power supply, IP65+ protection, lightning protection design. Low power consumption (<50W), suitable for long-term operation in remote or off-grid areas.

5. How does the flue gas pre-treatment system prevent high dust and humidity interference? What is the maintenance cycle? Equipped with multi-stage filtration (cyclone + membrane filter) + electronic condensation dehumidification + heated tracing lines, with automatic back-blowing to prevent clogging. Sensor lifespan 2–5 years (depending on gas). Recommended inspection of filters and zero/span calibration every 3–6 months. System self-diagnosis provides early maintenance warnings.

6. Can centralized monitoring of multiple chimneys or parameters be achieved? Are there communication distance limits? Supports multi-point networking via RS485 Modbus RTU or Ethernet to upper computer/SCADA. Single RS485 segment distance approx. 1200m; repeaters or 4G/LoRa wireless modules can be added to achieve unified monitoring of multiple chimneys and remote viewing.

7. Are there special designs for monitoring special gases such as HCl and HF? Uses corrosion-resistant probe and pipeline materials (PTFE/Hastelloy), dedicated electrochemical or UV sensors. Enhanced anti-corrosion pre-treatment, range 0–100 mg/m³ level, response time <60s, ensuring accurate monitoring of highly acidic gases without damaging equipment.

8. How to obtain complete selection manuals, installation cases, or quotations? What is the response time? Submit chimney type, target gases, temperature, and number of points via the official website. The technical team responds within 24 hours with a preliminary plan. Provides detailed manuals (parameter tables, probe dimension drawings, HJ212 protocol description), typical cases (thermal power/incineration layout diagrams), and 3D models. Standard configuration quoted within 1–3 working days; customized systems within 5–10 working days.

Conclusion: Nexisense Safeguards Every Breath of Freshness from Chimney Emissions

Chimney and exhaust stack monitoring is a critical part of fixed source environmental management. With high-precision sensors, reliable pre-treatment technology, and flexible customization capabilities, Nexisense provides complete solutions from single-parameter to full-index monitoring. Whether for new CEMS projects, grid-based air quality monitoring, or existing system upgrades, it ensures accurate data, stable transmission, and efficient compliance.

If your enterprise faces chimney emission monitoring or plant boundary air quality monitoring needs, welcome to contact the Nexisense team for tailored solutions, on-site surveys, and technical support. Green emissions begin with precise monitoring.