Dry air requirements for piping in industrial buildings
In industrial plant piping systems, the quality of dry air is directly related to production safety, equipment life and process stability. The following is a professional explanation from four dimensions: technical standards, core requirements, implementation paths and maintenance specifications:
1. Core technical indicators of dry air
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Pressure dew point control
It needs to reach below-20℃ (some precision processes require-40℃ to-70℃). This indicator reflects the saturation state of water in the air. The lower the dew point, the higher the dryness of the air. For example, when the dew point is-40℃, the water content in the air is only 0.1g/m³, which can effectively avoid the formation of condensed water in the pipeline. -
Moisture content limitation
It needs to be less than 100mg/m³ (some industries require ≤10mg/m³), and real-time monitoring through a high-precision trace water detector to ensure that the compressed air will not cause pipeline corrosion or process medium pollution due to excessive moisture. -
System tightness verification
It needs to pass a 24-hour pressure holding test, and the pressure change rate is ≤1%. For example, for pipes with an initial pressure of 0.8MPa, the pressure must not be lower than 0.792MPa after 24 hours to eliminate the risk of minor leakage.
2. The key impact of dry air on piping systems
- Process safety risks
- Excessive moisture can cause hydrate formation in natural gas pipelines and block valves and instruments (such as pressure transmitters and flow meters).
- In chemical pipelines, liquid water reacts with acidic gases (such as H ˇ S, CO ˇ) to form corrosive acid liquids, which accelerate the corrosion of the inner wall of the pipeline.
- Equipment operating efficiency
- Moisture content in compressor intake air will reduce volumetric efficiency and increase energy consumption. Experimental data shows that for every 10 ° C increase in the intake dew point, the compressor efficiency decreases by 3%-5%.
- Condensate water can cause seals of pneumatic actuators (such as cylinders and pneumatic valves) to expand and jam, shortening equipment life.
- product quality risk
In food and pharmaceutical packaging pipelines, excessive moisture will breed microorganisms and contaminate products; during the spraying process, humid air will cause foaming of the paint film and decrease in adhesion.
3. Realization path of dry air system
- Air compressor selection
- Priority is given to water-lubricated screw air compressors, whose exhaust oil content is ≤0.01mg/m³ to avoid oil pollution of pipelines.
- Equipped with a frequency conversion drive system, the speed is automatically adjusted according to the air load, and the energy saving rate can reach 30%-40%.
- Post-processing equipment configuration
- dryer: Freeze dryer (dew point 2-10℃) is suitable for general processes; adsorption dryer (dew point-40℃ to-70℃) is used for precision manufacturing.
- filter: Three-level filtration system (oil removal, dust removal, odor removal) ensures that the cleanliness of compressed air reaches ISO 8573-1 standard.
- air storage tank: The recommended volume is 1/6-1/4 of the compressor displacement to buffer pressure fluctuations and stabilize the air supply.
- Special process guarantee
- nitrogen replacement: After the pipe is dried, inject nitrogen to maintain a slight positive pressure (0.5 bar) to prevent moisture from regaining.
- intelligent monitoring: Install dew point sensors and pressure transmitters, upload data to the SCADA system in real time to achieve early warning and traceability.
4. Maintenance and acceptance standards
- Daily maintenance specifications
- drainage management: The automatic drain valve is checked daily, and the air storage tank is manually drained weekly.
- filter replacement: Precision filters are replaced every 2000 hours, and oil-water separators are cleaned monthly.
- dew point detection: Use a portable dew point meter to randomly inspect key points every quarter to ensure that the data meets process requirements.
- acceptance criteria
- dryness verification: The dew point of exhaust gas for 4 consecutive hours is 5 ° C lower than the operating temperature of the pipeline (such as the ambient temperature is 30 ° C, and the dew point needs to be ≤25 ° C).
- tightness testing: The pressure change during the 24-hour pressure holding test is ≤1%, and the residual water on the inner wall of the pipe is ≤2.1mg/m² (at the dew point of-20℃).
- file record: Complete documents such as drying curve chart, dew point-time data sheet, pressure change record are required.
5. Typical application scenarios
| industry | drying requirements | risk cases |
|---|---|---|
| natural gas transmission | Dew point ≤-20 ℃, water content ≤ 100 mg/m ³ | Due to incomplete drying of a certain pipeline, hydrate clogging occurred, resulting in a 24-hour shutdown of the entire line and a loss of more than 5 million yuan. |
| food packaging | Dew point ≤-40 ℃, cleanliness ISO 8573 – 1:2 | A beverage factory caused excessive microorganisms in the packaging film due to oil in the compressed air, and the product recall rate reached 8%. |
| Precision electronics manufacturing | Dew point ≤-60 ℃, dust content ≤ 0.1 μ m | In a chip factory, humid air caused fog on the lens of a lithography machine, causing a 15% drop in the yield of batch products. |
Through strict technical control and systematic maintenance, the quality of dry air used in industrial plant pipelines can be ensured, providing basic guarantee for production safety and product quality.
