1. Introduction

In the factory area with numerous chemical towers and tanks, in the scorching furnace of garbage incineration, and in the cold box of the air separation unit at minus 200 ℃, gas molecules shuttle back and forth like 'invisible visitors'. They either participate in reactions, threaten safety, or influence emission standards. How to inform the operator in real-time about the composition, concentration, and whereabouts of these 'visitors'? Siemens' 70 year old solution - gas analyzer - enables invisible molecules to speak. Today, from ULTRAMAT, OXYMAT to SITRANS TDL, Siemens has built a full spectrum platform covering infrared, ultraviolet, thermal conductivity, laser, paramagnetic, electrochemical, and chromatographic technologies, providing a 'continuous, accurate, and intelligent' gas data base for industrial processes and environmental protection.

2、 Technical lineage: Six principles, each performing its own duties

1. Non dispersive infrared (NDIR) - 'versatile'

The ULTRAMAT 23/6 series uses NDIR technology to achieve ppm level detection by utilizing the characteristic absorption of molecules such as CO ₂, CO, SO ₂, CH ₄ in the 2-10 µ m wavelength range. Dual channel differential design can offset light source aging and window pollution, with drift<1% FS/month; The modular light cell supports simultaneous measurement of three components, with a response time of T90<3 s, and is the main force for CEMS and combustion optimization.

2. Paramagnetic Oxygen - 'Oxygen Expert'

OXYMAT 6 is based on the strong paramagnetism of oxygen, which forms a 'magnetic wind' in an alternating magnetic field, changes the resistance of the heating wire, and thus measures the oxygen concentration in the range of 0-100%; OXYMAT 64 switches to the ZrO ₂ solid-state potential method, which provides a detection limit of 0.1 ppm in the trace range of 0-10 ppm, ensuring the quality of high-purity nitrogen and argon in air separation.

3. Thermal conductivity - 'Light Gas Catcher'

CALOMAT 6 utilizes the high thermal conductivity of H ₂ and He to form a difference with N ₂ carrier gas, achieving arbitrary switching between 0-1% and 0-100% stages, T90＜2 s， Suitable for online monitoring of hydrogen purity in hydrogen production, chlor alkali, and synthetic ammonia plants.

4. Laser diode (TDLAS) - 'in-situ fast shooter'

SITRANS TDL directs a 760 nm, 1.65 µ m laser beam directly onto the process pipeline. Wavelength scanning and harmonic detection enable the measurement of NH3, HCl, HF, CO, and O ₂ without sampling, with a response of less than 1 second, an optical path length of 1-10 m, and a resolution of up to 0.1 ppm. It is a real-time closed-loop system for SCR denitrification and hydrochloric acid absorption towers.

5. Flame ionization detector (FID) - 'total hydrocarbon magnifying glass'

FIDAMAT 6 ionizes hydrocarbons through a hydrogen flame to measure total hydrocarbon (THC) concentration with a detection limit of 0.1 ppm. It is used for air separation cold box explosion risk warning and engine bench emission testing.

6. Gas Chromatography (GC) - 'Trace Fingerprint Database'

The MAXUM II series integrates multiple valves and columns into an explosion-proof box, allowing for the separation of over 30 components including hydrocarbons, oxygen, and sulfur in a single injection, with a reproducibility of ± 1%. It provides' laboratory level 'online data for ethylene cracking and ethylene oxide processes.

3、 Star products: from 'little steel cannon' to 'giant'

-ULTRAMAT 23:19 rack, any combination of 3 components, IP65， Price friendly, it is the entry-level standard for CEMS for small and medium-sized enterprises.

-ULTRAMAT 6: The high-temperature light cell version can directly measure SO ₂ and SO2 in flue gas at 190 ℃ NOx， Drift<0.5% FS/week, meeting the German 17.BImShhV standard.

-OXYMAT 64: ZrO ₂ solid-state sensor, 650 ℃ constant temperature, 0-10 ppm O ₂ detection limit of 0.1 ppm, annual drift<2%, high-purity nitrogen gold standard for air separation.

-SITRANS TDL: Cross Direct in-situ installation, no sampling required, 1-second response, SCR denitration NH3 escape ≤ 2 ppm closed-loop control.

-CALOMAT 6:0-100% H ₂ single range, explosion-proof zone 1, used for monitoring the hydrogen purity of fresh ammonia synthesis gas at 99.9995%.

-MAXUM II: With dual furnaces and dual detectors, complete the full analysis of benzene, toluene, and styrene in 8 minutes, making it a powerful tool for petrochemical plants to meet GB 31571 standards.

4、 Siemens gas analyzer application scenarios: from flame to cold flame, from chimney to torch

1. Thermal power and waste incineration

At the 660 MW coal-fired unit, 7MB2335-0MJ00-1AA1 simultaneously measured SO ₂, NOx, CO, and O ₂, and the data was connected to DCS through MODBUS RTU. The desulfurization efficiency increased from 92% to 98%, and the annual emission reduction of SO ₂ was 210 tons. At the 750 t/d garbage furnace, the HCl and HF laser in-situ systems were interlocked with the lime slurry pump, and the acid mist emissions were reduced to below 5 mg/Nm ³.

2. Steel and cement

Blast furnace gas contains 22-25% CO, and OXYMAT 6 controls the oxygen concentration below 0.2% to prevent bag filter explosions; The dual parameter closed loop of CO and NOx in the tail gas of the rotary kiln reduces the kiln temperature by 30 ℃, lowers the coal consumption per ton of clinker by 2 kg, and saves 1 million yuan annually.

3. Air separation and hydrogen production

OXYMAT 64 monitors nitrogen products with an oxygen content of ≤ 1 ppm to ensure that there is no oxidation or coloring inside the fiber preform furnace; CALOMAT 6 measures 99.999% H ₂, providing purity data for 70 MPa hydrogen refueling stations. Fuel cell vehicles can save 0.3 kg of hydrogen per 100 km.

4. Petrochemicals and pharmaceuticals

MAXUM II online monitoring of C ₂ H ₄, O ₂, and CO ₂ in the circulating gas of the ethylene oxide plant, increased selectivity from 80% to 87%, and increased annual production by 18000 tons; FIDAMAT 6 sets the THC alarm value in the solvent storage tank area at 50 ppm, resulting in a 90% reduction in unorganized VOCs emissions.

5、 Digital Twin: From 'Analyzer' to 'Analysis Ecology'

Siemens has integrated gas analyzers into PCS 7 and MindSphere, endowing them with three new capabilities:

-Predictive maintenance - AI compares light intensity attenuation curves, providing 14 days advance warning of light source lifespan and reducing unplanned shutdowns by 60%;

-Digital Calibration - Automatically download the latest linearization coefficients of EPA and T Ü V from the cloud, without the need for manual calibration;

-Carbon Emissions Accounting - The system automatically generates hourly CO ₂ emission data in accordance with GB/T 32150, seamlessly integrating with the national carbon market platform.

6、 Siemens gas analyzer selection and maintenance: ensuring precise and long-lasting online performance

1. Sample gas treatment: High temperature and high dust flue gas must be equipped with a 180 ℃ heat tracing tube and ceramic filter element to avoid SO ₂ dissolving in condensed water and causing 'false negative values';

2. Range matching: When SO ₂ has ultra-low emissions of 20 mg/Nm ³, select the minimum range of 0-100 ppm, resolution of 0.1 ppm, and relative error<2%;

3. Calibration cycle: NDIR recommends checking with 80% FS standard gas every 3 months. If the drift is greater than 1%, single point calibration will be automatically triggered;

4. Explosion proof area: Select Ex d casing for Zone 1, use Ex p positive pressure blowing for Zone 2, and change CALOMAT 6 sensor to inert platinum wire in hydrogen environment to prevent catalytic reaction.

7、 Conclusion

From the first paramagnetic oxygen meter in the 1950s to today's lasers AI、 With the triple support of cloud computing, Siemens gas analyzers always revolve around the same mission: turning the 'unknown' into the 'known', and upgrading 'experience' into 'data'. Driven by the dual carbon, dual control, and dual carbon emission markets, analytical instruments are no longer just instruments, but the core data source for process optimization, compliant emissions, safety warning, and transaction settlement. Choosing Siemens means choosing a 'continuous, precise, and verifiable' gas data chain - turning invisible molecules into quantifiable, predictable, and profitable production factors.