GB/T 38685-2020 in English
VALIDDetermination of sulphuric acid mist in tail gas for sulphuric acid industry
- Issued on:2020-03-31
- Implemented on:2021-02-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 38685-2020硫酸工业尾气硫酸雾的测定方法》由TC63（全国化学标准化技术委员会）归口，TC63SC7（全国化学标准化技术委员会硫和硫酸分会）执行，主管部门为中国石油和化学工业联合会。
Introduction
Technical background and scope of application of the standard
As the core supporting method for the control of pollutant emissions from the sulfuric acid industry, this standard establishes an accurate measurement system for sulfuric acid mist (containing sulfuric acid droplets and sulfur trioxide) generated during the production process. In terms of technological evolution, it breaks through the limitations of traditional single filter membrane sampling and innovatively adopts a composite sampling scheme of glass fiber filter cartridge in series with isopropyl alcohol absorption bottle.
Core Determination Principle
| Components | Collection Method | Analytical Method | Detection Limit |
|---|---|---|---|
| Sulfuric Acid Droplets | Physical Retention of Cartridges | Acid-Base Titration | 0.5mg/m³ |
| Sulfur Trioxide | Isopropyl Alcohol Chemical Absorption | Thorium Reagent Titration | 0.2mg/m³ |
Key Operation Points
Sampling system configuration
Typical sampling devices should include: 120-130℃ constant temperature smoke gun, three-level glass screen plate absorption bottle (each containing 100mL 80% isopropyl alcohol), ice water bath cooling device. Pay special attention to the sampling flow rate, which should be controlled within the range of 5-15L/min to ensure the accuracy of isokinetic sampling.
Reagent quality control
Isopropyl alcohol should pass the ultraviolet absorbance test (≤0.1 at 352nm), and the barium perchlorate standard solution should be calibrated with sulfuric acid standard solution, and the relative deviation should be ≤1%.
Data processing specifications
The total sulfuric acid mist concentration calculation formula is: ρ=ρ₁+ρ₂, where:
- ρ₁ (filter cartridge part): select formula (2) or formula (3) for calculation based on the titration consumption
- ρ₂ (absorption liquid part): calculate the total of three bottles of absorption liquid according to formula (4)
The relative deviation of parallel determination is allowed to be ≤30%, and the final result is retained to one decimal place.
Implementation suggestions
Quality control points
1. System air tightness test is required before sampling, and the leakage rate should be ＜5%
2. The absorption liquid should be analyzed within 4 hours after sampling
3. Each batch of samples needs to be tested for blank cartridges simultaneously
Safety warning
When operating with concentrated sulfuric acid, sulfur trioxide and other dangerous chemicals, you must wear an acid-proof mask and corrosion-resistant gloves, and the experimental area should be equipped with an emergency eyewash device.
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