Industrial Fixed-Source VOCs Online Monitoring System: PID/FID Technology Integration Solution

Engineering Necessity and Policy Background of VOCs Emission Monitoring

Volatile organic compounds (VOCs), as key precursors to ozone and secondary PM2.5, have fixed-source emissions mainly originating from petrochemical, organic synthesis, surface coating, pharmaceutical, printing and packaging, and other industries. According to relevant specifications from the Ministry of Ecology and Environment and local standards (such as GB 37822-2019 "Volatile Organic Compounds Unorganized Emission Control Standard", GB 31571-2015 "Pollutant Emission Standard for Petroleum Chemical Industry", and dynamic revisions in 2025-2026), industrial enterprises must implement continuous monitoring of non-methane total hydrocarbons (NMHC), total volatile organic compounds (TVOC), or characteristic factors (such as benzene series) for organized emissions, and conduct mobile or boundary monitoring for unorganized dispersion.

The NiuBoL system uses photoionization detector (PID) and flame ionization detector (FID) as core technology routes. PID is suitable for low-concentration, fast-response scenarios (such as boundary unorganized, leak detection), and FID is suitable for high-precision NMHC total monitoring. The equipment complies with HJ 38-2017 "Determination of Total Hydrocarbons, Methane and Non-Methane Total Hydrocarbons in Exhaust Gas from Stationary Sources - Gas Chromatography" and HJ 604-2017 methods, supporting online continuous sampling, pretreatment dehumidification/dust removal, and automatic data upload, meeting the acceptance and daily operation and maintenance needs of key industry VOCs governance projects.

VOCs Monitoring Technology Route Comparison and Selection Key Points

PID Technology Features and Applicability

PID is based on UV photoionization principle, sensitive to most VOCs (ionization energy<10.6eV), with response time <3s, no need for hydrogen/auxiliary gas, small size, low maintenance. Suitable for:

• Boundary unorganized emission monitoring

• Equipment/pipeline component leak detection (LDAR)

• Emergency leak warning

The NiuBoL PID module has a wide linear range (ppb~ppm level), strong anti-interference capability (calibrated with typical response factors such as benzene, toluene, TVOC), suitable for low-concentration scenarios in coating workshops and pharmaceutical workshops.

FID Technology Features and Applicability

FID has high sensitivity to hydrocarbons, wide linear range (0.1ppm~tens of thousands ppm), commonly used for NMHC total continuous monitoring. Requires hydrogen supply and flame maintenance, suitable for:

• Organized emission stack online monitoring

• Governance facility inlet/outlet efficiency assessment

The NiuBoL FID system integrates automatic ignition, hydrogen generator, and CH4 removal column, achieving automatic switching of total hydrocarbons-methane-NMHC, complying with HJ/T 38 standard.

Composite and Extension Solutions

NiuBoL provides PID+FID composite all-in-one machines or modular extensions supporting GC-MS characteristic component analysis and FTIR multi-component scanning. When selecting, consider:

• Emission concentration range and characteristic pollutants

• Whether explosion-proof is needed (Ex d IIC T6)

• Communication protocol and platform docking requirements

Composition and Engineering Deployment Key Points of Industrial Fixed-Source VOCs Online Monitoring System

• Sampling Pretreatment Unit: Heated sampling pipeline (above 120℃), condensation dehumidification, particulate filtration, ensuring stable transmission of high-temperature and high-humidity exhaust gas.

• Analysis Module: PID/FID host + data acquisition controller.

• Power Supply and Communication: Solar + lithium battery redundancy (≥7 days in rainy conditions), RS485 Modbus RTU / 4G MQTT / LoRaWAN.

• Auxiliary Functions: Audible and visual alarms, flow meters, temperature-pressure compensation, emission rate calculation (according to GB/T 16157 isokinetic sampling principle).

Deployment Notes: Sampling points comply with HJ/T 397 specifications (straight pipe section 8D+2D), platform height ≥15m, reserve sampling holes and testing platforms; select Ex-certified models for explosion-proof areas.

Main Application Scenarios and Project Cases of Industrial Fixed-Source VOCs Online Monitoring

Petrochemical and Refining Industry

Deployed at storage tank breather valves, loading platforms, process tail gas emission stacks, monitoring NMHC, benzene, toluene, etc. Typical Case: In a refining and chemical enterprise VOCs governance transformation project in East China, the NiuBoL FID online system accesses enterprise DCS, calculates emission rates in real time, with governance efficiency assessment reaching over 95%, supporting total accounting and emission permit execution.

Surface Coating and Automobile Manufacturing

Coating workshop spray paint exhaust gas monitoring TVOC and benzene series. Project Practice: In the Yangtze River Delta automobile parts coating line, PID boundary + FID emission stack combined monitoring, data uploaded to cloud platform linking RTO incinerator regulation, automatic load reduction on exceeding limits, VOCs reduction volume annually over 30%.

Pharmaceutical and Fine Chemical

Synthesis reaction tail gas, solvent recovery system monitoring. Case: In a raw material pharmaceutical enterprise in North China, the NiuBoL composite system monitors chlorinated hydrocarbons and nitrogen-containing organics, integrated Modbus to workshop PLC, achieving characteristic factor threshold alarms and process optimization linkage.

Printing Packaging and Industrial Coating

Printing machine tail gas, drying exhaust gas monitoring. After integration, data supports park VOCs traceability platform, assisting mobile vehicle verification.

System Integration Solution and Compatibility

Protocol Support

• Modbus RTU over RS485: Standard register table, supports PLC direct reading of concentration, flow, alarm status.

• MQTT over 4G: TLS encryption, direct connection to Alibaba Cloud IoT/Huawei Cloud IoTDA, achieving remote configuration and OTA.

• LoRaWAN: Low-power networking, suitable for park multi-point monitoring.

Integration Considerations

1. Pretreatment Matching: Heated tracing for high-temperature exhaust, condenser for high humidity.

2. Data Calibration: Quarterly PID lamp cleaning, FID hydrogen purity verification, response factor calibration.

3. Alarm Linkage: Threshold triggers relay or cloud push to governance equipment.

4. Platform Docking: Supports HJ 212 protocol upload to ecological environment department platforms.

5. Explosion-Proof and Safety: Ex d certification, grounding<4Ω, SPD lightning protection.

6. Maintenance Strategy: Remote self-diagnosis + annual on-site calibration, reducing operation and maintenance costs.

Main Technical Parameters of NiuBoL VOCs Online Monitoring System

FAQ:

Q1. Which industry fixed sources is the NiuBoL VOCs system suitable for monitoring?
A: Mainly suitable for key VOCs emission industries such as petrochemical, pharmaceutical, coating, printing, supporting organized emission stacks and unorganized boundary monitoring.

Q2. How to choose or combine PID and FID?
A: PID is suitable for fast, low-concentration unorganized/leak monitoring; FID is suitable for precise NMHC total measurement; composite solutions balance response speed and total compliance.

Q3. What are the special requirements for installation in explosion-proof areas?
A: Select Ex d IIC T6 certified models, anti-static sampling pipelines, grounding resistance<4Ω, installation location complies with explosion hazard zoning.

Q4. How to handle high-temperature and high-humidity exhaust gas?
A: Equipped with heated sampling pipelines (>120℃) + condensation dehumidifiers to ensure stable sample gas transmission and avoid condensation loss of polar VOCs.

Q5. How to achieve integration with enterprise existing SCADA/environmental platforms?
A: Docking via Modbus RTU or MQTT protocol, supporting custom register mapping and topic subscription for real-time synchronization of concentration, flow, alarms.

Conclusion

VOCs online monitoring is a key technical link for industrial enterprises to achieve green transformation, compliance emissions, and environmental responsibility fulfillment. The NiuBoL system, with reliable PID/FID detection core, flexible integration protocols, and engineering deployment solutions as its core, has been operating stably in multiple chemical, coating, and pharmaceutical projects, helping integrators efficiently deliver VOCs governance subsystems and smart environmental platforms. If you need selection consultation, on-site survey, protocol testing, or customized explosion-proof solutions, welcome to contact the NiuBoL technical team to jointly optimize your fixed-source VOCs monitoring and control projects.