Steel Smelting Industry Gas Detection Solution: Nexisense Guards High-Risk Production Safety

China, as the world's largest steel-producing country, has its steel smelting industry supporting infrastructure construction and manufacturing development. The conversion process from pig iron to finished steel involves multiple processes such as converters, electric furnaces, and refining furnaces, with core processes including oxidation-reduction, dephosphorization and desulfurization, alloying, etc. These high-temperature, high-pressure, and confined environments inevitably produce carbon monoxide, sulfur dioxide, combustible gases (such as coke oven gas, hydrogen, etc.), and oxygen concentration fluctuations. If gases leak or concentrations get out of control, they not only threaten the lives of operators but may also cause explosions, fires, or environmental pollution accidents. In recent years, the state has continuously tightened safety and emission standards for the steel industry (such as GB 28662-2012 Emission standard of air pollutants for sintering flue gas of iron and steel industry, GB 28663-2012 Emission standard of air pollutants for iron and steel industry), making real-time and reliable gas monitoring an essential safety measure.

Nexisense deeply cultivates industrial gas sensing technology, and its SGA-500 series online gas detectors combined with SGA-800 series alarm controllers provide a full-chain monitoring solution for steel smelting, which has been stably operating in multiple large steel plants such as Maanshan Iron & Steel, Anshan Iron & Steel, and Baosteel, helping enterprises transition from passive response to active prevention.

Analysis of Gas Risks in the Steel Smelting Process

Gas risks in steel smelting run through the entire production chain, mainly concentrated in the following links:

• Converter/electric furnace smelting area: Oxygen blowing for decarburization produces a large amount of CO, and oxygen concentration needs precise control (too high easily causes explosion, too low affects efficiency). Excessive CO concentration can lead to acute poisoning.

• Desulfurization and dephosphorization area: Sulfur compounds oxidize to generate SO₂, which is highly irritating and damages the respiratory system upon long-term exposure.

• Gas generation and transportation system: Blast furnace gas and converter gas contain combustible components such as CO, H₂, CH₄, etc., and leaks are extremely prone to cause deflagration.

• Refining and continuous casting area: Even under nitrogen and argon protection, residual CO₂ or CO may accumulate, with high risk of oxygen deficiency in confined spaces.

These gases have different characteristics: CO is colorless and odorless with extremely high toxicity; SO₂ is acidic and corrosive; combustible gases have low explosion limits (CO 12.5%, H₂ 4%). Traditional inspection methods have insufficient coverage and delayed response, while professional online monitoring systems can achieve 24-hour continuous coverage with second-level response, significantly reducing accident probability.

Core Products of Nexisense Gas Detection for Steel Smelting

Nexisense products are based on original imported sensors, with secondary calibration, temperature and humidity compensation, and anti-electromagnetic interference optimization, adapting to the high-temperature (up to 60℃), dusty, and corrosive environment of steel plants.

Details of SGA-500 Online Gas Detector

Specially designed for fixed points, suitable for converter platforms, gas pipelines, furnace tops, etc. Core advantages:

• Comprehensive gas coverage: CO (0-1000 ppm), SO₂ (0-100 ppm), combustible gases (0-100% LEL), O₂ (0-30% VOL), supporting multi-channel combination.

• Output and linkage: 4-20mA current loop, RS485 Modbus-RTU, relay switch quantity, directly connected to PLC/DCS or SGA-800 controller.

• Sampling and protection: Diffusion/pump suction optional, Ex d IIC T6 Gb explosion-proof certification, IP65/66 protection level, resistant to acid and alkali corrosion.

• Flexible alarm: High and low alarm thresholds adjustable on site (e.g., CO 50/200 ppm), built-in audible and visual alarm, linking ventilation and shut-off valves.

Factory calibrated, plug-and-play, sensor lifespan 2-5 years, low maintenance cost.

Added Value of SGA-800 Series Alarm Controller

As a central device, installed in the central control room or duty room:

• Unified power supply and management: Supports access of up to 32 detectors, centrally displaying real-time concentrations.

• Linkage extension: Triggers audible and visual alarms, fan start, gas valve closure, and even SMS/voice notification when exceeding limits.

• Data recording: Stores historical curves and alarm logs, supports USB export or cloud upload, convenient for post-analysis and safety supervision filing.

The combination of both forms a "detection-alarm-response" closed loop, greatly improving emergency response efficiency.

Typical Application Scenarios and Market Validation

Actual deployment in steel plants:

• Converter smelting platform: SGA-500 monitors CO and O₂, automatically reducing oxygen or stopping in case of abnormality.

• Blast furnace gas area: Monitors combustible gases and CO, linking shut-off system to prevent deflagration.

• Desulfurization workshop: Online SO₂ monitoring to ensure emission compliance.

• Plant inspection and emergency: Combined with portable equipment to supplement blind spots.

Feedback from multiple steel plants: After integrating SGA-500 + SGA-800 in a certain plant of Maanshan Iron & Steel, CO poisoning incidents reached zero, and gas-related downtime decreased by 35%; in the Baosteel project, system data was directly connected to the environmental platform, successfully passing the annual audit.

Practical Suggestions for Implementing Gas Detection Systems

During selection, consider furnace type (converter/electric furnace), gas type (blast furnace/converter gas), and concentration range. Installation locations should be upstream of gas accumulation points, avoiding high-temperature radiation sources. Perform regular calibration (every 6-12 months) using standard gas cylinders to ensure accuracy. Combined with IoT, remote monitoring and predictive maintenance can be achieved to further reduce operational risks.

Common Questions and Answers (FAQ)

Q1: Which gases in steel smelting are mainly supported by the Nexisense SGA-500 series? Can range and sensor customization be performed for blast furnace, converter, or electric furnace processes?

A1: Standard configuration covers carbon monoxide (CO), sulfur dioxide (SO₂), combustible gases (LEL, including CO, H₂, CH₄), oxygen (O₂), and some models support carbon dioxide (CO₂) and nitrogen oxides (NOx). Customization is available for different furnace types: such as converter CO high range (0-2000 ppm), blast furnace gas low explosion limit high sensitivity, desulfurization zone SO₂ high-selectivity sensor. We perform sensor selection, cross-interference compensation optimization, and algorithm adjustment based on customer-provided gas composition analysis, historical concentration peaks, process parameters, and emission regulatory requirements, usually delivering prototypes in 4-8 weeks to ensure seamless matching with gas recovery and desulfurization/denitrification systems.

Q2: How is the long-term stability and anti-interference capability of the online SGA-500 in high-temperature, dusty, and strong electromagnetic interference environments of steel plants?

A2: The product adopts 316L stainless steel corrosion-resistant shell, IP65/IP66 protection, operating temperature range -20～+60℃ (optional high-temperature version up to +80℃), with advanced built-in temperature and humidity compensation, multi-stage digital filtering, and electromagnetic shielding design. In actual converter platform continuous operation projects, after 6000 hours, zero drift <±2% FS, span error <±5%, dust interference controlled within ±4%. Recommended measures: 1) Installation location avoids direct high-temperature radiation and dust injection; 2) Add dust-proof cooling jacket; 3) Clean probe surface monthly; 4) Perform zero calibration with clean air quarterly; 5) Use shielded cables in areas with severe electromagnetic interference.

Q3: How does the SGA-800 alarm controller achieve multi-point centralized management and complex linkage control?

A3: Supports 32-channel RS485 bus access (expandable), one screen displays real-time concentration, status, and trend curves of all monitoring points; built-in large-capacity storage (supports more than 1 year of historical data); alarms divided into three levels (warning/alarm/high limit), each level independently configurable for threshold, delay, and linkage actions (e.g., CO 50 ppm starts ventilation, 200 ppm cuts off main gas valve, triggers audible/visual + SMS push). Provides Modbus protocol documentation, sample code, and host computer software, supporting integration with PLC/SCADA. In actual steel plant applications, it can achieve “automatic feed reduction after high limit confirmation” or “multi-point simultaneous exceedance linkage emergency shutdown”, effectively balancing safety and continuous production.

Q4: How does the detection system interface with the existing automation control system (such as PLC/DCS) in the steel plant? Is there ready-made resource support for quick integration?

A4: SGA-500 outputs standard 4-20mA (three-wire), RS485 Modbus-RTU, relay passive contacts, compatible with mainstream systems such as Siemens S7, ABB 800xA, Honeywell Experion. We provide free: Modbus register mapping table, communication protocol manual, ladder diagram/function block sample code, host computer monitoring software (real-time curves, historical query, alarm reports, automatic export). Integration cycle is usually 1-3 weeks; SGA-800 also supports MQTT protocol, which can upload data to the plant cloud platform for remote viewing and push on mobile/computer.

Q5: What key factors affect sensor lifespan? How to effectively plan maintenance cycles and control long-term costs?

A5: Electrochemical sensors typically last 2-4 years, infrared/catalytic combustion type 4-6 years. Main influencing factors: 1) Continuous high-concentration CO/SO₂ impact accelerates electrolyte consumption; 2) Dust/oil mist adhesion blocks the diaphragm; 3) Extreme temperature and humidity fluctuations cause baseline drift; 4) Electromagnetic interference. We recommend maintenance plan: monthly visual inspection of probe; quarterly zero calibration (clean air); annual or after accumulated 8000 operating hours, perform span calibration with standard gases; install multi-stage filters and cooling sleeves in high-dust/corrosive areas. Annual maintenance cost is about 12-18% of equipment total price. Nexisense provides modular sensor on-site replacement service (completed in 10-15 minutes) and annual maintenance contracts, with spare parts discounts for bulk purchases.

Q6: Has the product passed relevant national standards and certifications in the steel industry? How is it applied in environmental acceptance and safety supervision review?

A6: It has obtained national measuring instrument type approval (CMC), explosion-proof certificate (Ex d IIC T6 Gb), electromagnetic compatibility (EMC) testing, and complies with GB 28662-2012, GB 28663-2012 Emission standards of air pollutants for iron and steel industry, GB 50058-2014 Code for design of electric power installations in explosion and fire hazard atmospheres, etc. Detection data can be directly connected to environmental online monitoring platforms as objective evidence for emission compliance, occupational health protection, and safety risk assessment. Export models additionally meet IECEx/ATEX and CE requirements, providing bilingual Chinese-English certificates and calibration reports.

Q7: What hierarchical response mechanisms does the system have after gas concentration exceeds the limit? How to avoid unnecessary production interruptions caused by false alarms?

A7: Supports three-level alarm threshold settings (warning/alarm/high limit), each level independently configurable for concentration value, delay time (1-60 seconds to prevent transient fluctuations), and linkage strategy. Trigger responses include: 1) Local audible and visual alarm (≥90 dB); 2) Relay output controls ventilation, gas shut-off valve, warning lights; 3) RS485 sends alarm messages to central control; 4) Optional SMS/WeChat/APP push. False alarm control adopts concentration trend judgment, multi-point averaging filtering, environmental compensation algorithms, and supports “manual confirmation reset” or “continuous exceedance for N seconds before high limit linkage”. In actual projects, settings such as “only high limit automatic shutdown for toxic gases” can ensure the best balance between safety and production continuity.

Q8: How to quickly obtain specific selection schemes for steel plants, prototype trials, or on-site technical support?

A8: Please visit the “Contact Us” page on the Nexisense official website to submit requirements, or directly contact the sales/technical support team, providing the following information: furnace type (converter/electric furnace/blast furnace), gas type, main monitoring gases, concentration range, number of installation points, existing control system type, budget range. We usually reply within 24-48 hours with detailed selection tables, reference quotes, technical schemes, and typical cases. For key projects, free prototype trials (1-2 months, including on-site installation guidance, simulated gas testing, performance verification), or engineer on-site survey, layout, commissioning, and training can be arranged to ensure the scheme accurately matches the actual working conditions of the steel plant.

Summary

Gas detection in steel smelting is the cornerstone of safe production and green development. The combination of Nexisense SGA-500 and SGA-800, with high reliability and flexible integration, helps steel plants move from risk prevention to intelligent operation and maintenance. Under the dual pressure of the “dual carbon” goal and safety red lines, the early deployment of professional monitoring systems will provide a solid guarantee for the high-quality development of the industry. Nexisense will continue to focus on technological iteration and jointly guard every smelting safety with steel enterprises.