Air compressor cold dryer nitrogen machine working time

Specification for management of cooperative working time of air compressor, cold dryer and nitrogen generator

in the compressed air and nitrogen system, air compressor, cold dryer and nitrogen generator are the core equipment, and their working time configuration should follow the principle of technical logic and economic balance. Now the equipment operation characteristics and collaborative management requirements for professional description:

analysis of working characteristics of 1. equipment

1. air compressor operating characteristics
   • continuous operation capability: The oil-injected screw air compressor can run continuously for ≥ 8000 hours/year, but the exhaust temperature, oil level and other parameters should be recorded every 4 hours.
   • Loading rate control: It is recommended to keep the loading rate of 60%-80%, and start the intelligent start-stop function when it is lower than 50%.
   • Heat dissipation requirements: For every 10 ℃ increase in ambient temperature, the continuous operation time shall be shortened by 20%, and the environment above 40 ℃ shall be forced to ventilate.
2. Cold dryer operation boundary
   • temperature Adaptability: It can operate continuously under the ambient temperature of 5-38 ℃, and the precooling unit shall be configured if it exceeds the range.
   • pressure drop control: When the pressure difference between the inlet and outlet is> 0.07MPa, the heat exchanger needs to be cleaned, otherwise the frost formation speed of the evaporator will be accelerated by 30% for every increase in the pressure difference of 0.01MPa.
   • dew point monitoring: The pressure dew point shall be maintained at 2-10 ℃, and the refrigerant charge shall be checked when the temperature is lower than -20 ℃.
3. Nitrogen making machine operation constraints
   • life of molecular sieve: Carbon molecular sieves need to be activated after 20000 hours of continuous operation, otherwise the purity of nitrogen production will drop by 0.1 per hour.
   • Differential pressure management when the pressure difference of the adsorption tower is greater than 0.05MPa, the muffler shall be replaced to avoid damage to the control valve due to airflow pulsation.
   • Purity maintenance: 99.99% high purity nitrogen shall be sampled and tested every 2 hours, and the blowback system shall be checked when the oxygen content is> 10ppm.

2. Collaboration Time Configuration

1. conventional production mode
   • start sequence air compressor & rarr; Cold dryer (delay 5 minutes) & rarr; Nitrogen generator (delay 10 minutes)
   • operation cycle: Three machines operate synchronously and continuously, and equipment inspection shall be carried out for 15 minutes per shift (8 hours).
   • Shutdown sequence: Nitrogen making machine & rarr; Cold dryer (delay 10 minutes) & rarr; Air compressor (delay 5 minutes)
2. intermittent production mode
   • air compressor strategy: Adopt frequency conversion control to maintain 30% low frequency operation during non-gas period
   • cold dryer management: Ambient temperature <25 ℃ can be intermittent operation, but single downtime <4 hours
   • requirements for nitrogen making machine regeneration of molecular sieve is required after shutdown for more than 2 hours, and the regeneration temperature is ≥ 180 ℃
3. special conditions to deal
   • high temperature warning: When the exhaust temperature of the air compressor is> 85 ℃, the three machines will run synchronously and reduce the load by 20% per hour.
   • Low voltage protection: When the system pressure is less than 0.5MPa, the nitrogen making machine automatically switches to the pressure holding mode to maintain the pressure of the adsorption tower
   • emergency stop: When any equipment has a major failure, the three machines will stop synchronously, and restart according to the startup sequence after troubleshooting

3. life extension measures

1. air compressor maintenance
   • replace the oil and gas separator every 2000 hours to avoid motor overload caused by pressure difference> 0.1MPa
   • condensate water is discharged every 500 hours to prevent the emulsion from entering the host and causing rotor wear
2. maintenance of cold dryer
   • the water condenser is cleaned every quarter, and the heat transfer efficiency decreases by 40% when the fouling thickness is> 1.5mm.
   • Replace the refrigerant dry filter every year, and increase the risk of ice blockage by 3 times when the water content is> 100ppm
3. maintenance of nitrogen generator
   • check the pneumatic valve sealing ring every 1000 hours, and replace it when the leakage is> 0.5NL/min.
   • Replenish or replace the molecular sieve every two years, and the nitrogen production efficiency will be affected when the static adsorption attenuation is more than 15%.

4. intelligent monitoring recommendations

1. establishing a digital twin system
   • real-time acquisition of three machine operation data, drawing load curve, energy consumption curve, pressure curve
   • set up three-level warning mechanism: yellow warning (parameter deviation 15%), orange warning (deviation 30%) and red warning (deviation 50%)
2. implement preventive maintenance
   • automatically generate maintenance work orders according to equipment operating hours, with the advance of replacement cycle of key components ≥ 10%
   • establish spare parts life database and record the replacement records of consumables such as molecular sieve, filter and lubricating oil.

Enterprises should formulate the "compressed air and nitrogen system operation procedures", clear equipment start and stop standards, parameter monitoring frequency, abnormal disposal process. Through the implementation of TPM full production and maintenance, the overall equipment efficiency (OEE) can be increased to more than 85%, the life of key components can be extended by 30%-50%, and the system energy consumption can be reduced by 12%-18%.