1、 Overview of Core Operating Condition Classification and Technical Challenges

Sulfuric acid mist is mainly generated in industrial processes that use or generate sulfuric acid, fuming sulfuric acid, and high-temperature oxidation of sulfur-containing substances. Its operating characteristics can be summarized as "three highs and one interference":Highly corrosiveHigh humidity/easy to condensehigh temperatureComplex interference.

2、 Detailed explanation of typical application conditions

Condition 1: Sulfuric acid production and smoke sulfuric acid absorption process

Process DescriptionAt the outlet of the secondary absorption tower and smoke sulfuric acid absorption tower in the sulfuric acid plant. The concentration of sulfuric acid here is a key point for monitoring process efficiency and leakage.

Characteristics of working conditionsThe gas contains bothHigh concentration gaseous H ₂ SO ₄, SO ₂, SO ∝The temperature is moderate (~80-150 ° C) and the humidity is high.

Testing Challenge：

Strong corrosionRequirements for material corrosion resistance.

Cross interferenceIt is necessary to accurately distinguish and measure H ₂ SO ₄, without interference from high background SO ₂ and SO ∝.

Condition 2: Metal pickling, electroplating, and battery formation processes

Process DescriptionUsing sulfuric acid for steel pickling, metal electroplating, and lead-acid battery plate formation. The exhaust gas is discharged after being treated by the alkaline washing tower.

Characteristics of working conditions：Low temperature (often close to or slightly above room temperature), humidity saturation (after washing), containing a large amount of water vapor and alkali mist, sulfuric acid mist concentration is low but may fluctuate greatly.

Testing Challenge：

Condensation riskDue to low temperature and saturated humidity, any slight temperature drop can cause sulfuric acid and water to condense simultaneously, resulting in significant sampling losses.

Alkali mist interferenceWashing may carry alkali mist, which can neutralize with acid mist and affect measurement.

Condition 3: Smelting, coal-fired/oil boilers, hazardous waste incineration tail gas

Process DescriptionAfter sulfur-containing fuels or materials are burned at high temperatures, the SO ₂ in the flue gas is converted into SO ₂ under catalysts or low temperature conditions, and then combines with moisture to form sulfuric acid mist/acid dew point corrosion.

Characteristics of working conditions：The flue gas temperature is high (up to 200-400 ° C), the dust concentration is high, and the composition is complex (containing heavy metals and other acidic gases).

Testing Challenge：

High temperature and dustHigh temperature resistant probes and efficient multi-stage filtration are required to prevent dust from clogging and damaging the instrument.

Low concentration measurementThe concentration of sulfuric acid mist may be low (ppm level).

Condition 4: Workplace (acid pickling workshop, chemical plant) environmental air monitoring

Process DescriptionMonitor the concentration of sulfuric acid mist in the air of workers' breathing belts and assess occupational exposure risks.

Characteristics of working conditions：At room temperature and pressure, with low concentration (required to reach mg/m ³), there are various possible interfering aerosols.

Testing Challenge：

Form and interferenceSulfuric acid mist exists in the form of small droplets and needs to be distinguished from oil mist, other acid mist, and dust.

3、 The Golden Rule of Selection and Implementation

1. First working conditions, then technologyAlways based on specific circumstancesTemperature, humidity, corrosiveness, interferents, concentration rangeChoose technology.

2. High temperature heat tracing is the lifelineFor online or manual monitoring of any organized emission source,Prevent sulfuric acid condensationIt is the overriding primary consideration.

3. Pay attention to pre-processing systems：The process of preprocessing system (sampling, filtering, heat tracing, dehumidification) is often very important

summarySulfuric acid mist detection is a highly difficult topic in the field of gas monitoring, and the selection and configuration are based on specific working conditions.