How to estimate how much gas a factory will use

To estimate the usage of compressed air in the plant, a comprehensive analysis of equipment list, process parameters and system losses shall be carried out. The following is a systematic estimation process based on industry practice:

1. basic data collection

1. general survey of gas-using equipment
   • prepare "Compressed Air Equipment Account", record the equipment name, model, quantity, rated power (kW) and single gas consumption (m & sup3;/min)
   • typical equipment gas reference value:

     Device Type	gas consumption per unit (m & sup3;/min)
     pneumatic wrench	0.3-0.8
     sandblasting machine	2.0-5.0
     bottle blowing machine	1.5-3.0
     CNC machining center	0.8-1.2

2. production process analysis
   • draw the Gas Process Flow Chart and mark the gas pressure (bar), flow rate (m & sup3;/min) and usage frequency of each process.
   • Identify continuous gas equipment (e. g. pneumatic conveying) and intermittent gas equipment (e. g. spot welder)
3. measurement of pipe network parameters
   • measure the main pipe diameter (DN), length (m) and current pressure loss (& Delta;P)
   • detect the leakage point of the existing system, and use ultrasonic leak detector to locate

2. gas consumption calculation model

1. theoretical calculation method
   • gas consumption of single equipment:
     Q equipment = 60 × & eta; Pneumatic P rated × k
     (k: air consumption coefficient of equipment, 0.2-0.3 for pneumatic tools; & eta; pneumatic: pneumatic efficiency, 0.7-0.8)
   • total gas consumption:
     Q total = & sum;Q equipment × t usage coefficient
     (T usage coefficient: 1.0 for single shift, 1.8 for double shift and 2.5 for three shift)
2. actual measurement verification method
   • install a gas flow meter in the main pipeline, monitor continuously for 72 hours, and record the peak and valley values
   • typical industry air density reference:

     Industry type	air density (m & sup3;/min · output value of ten thousand yuan)
     auto Parts	0.8-1.2
     food & Beverage	0.5-0.9
     textile printing and dyeing	1.0-1.5

3. system Loss Correction
   • leakage loss: total gas consumption ×(5-15%)
   • pressure correction factor:
     Kp = P actual P rated × 100%
     (For every 1bar decrease in pressure, the flow rate is reduced by about 7%)

3. special condition adjustment

1. pulse gas correction
   • for pulse gas equipment such as sand blasting and purging, the peak factor (1.5-2.0) shall be multiplied.
   • When the gas storage tank is configured, the tank capacity shall meet the following requirements:
     V storage ≥ & Delta;P allows q pulse × t pulse
2. temperature correction
   • gas consumption increase in high temperature environment (>40 ℃):
     Q correction = Q theory ×(1+0.03 ×(T & minus;20))
3. altitude Correction
   • for every 1000m elevation, the air density decreases by about 10%, and the air consumption needs to be increased:
     Q correction = Q theory × 1 & minus;0.0001 × H1
     (H: altitude, m)

validation of 4. estimation results

1. unit output value method
   • compared with the gas consumption per unit of output value in the same industry, if the deviation of the estimated value is more than 30%, the equipment list shall be reviewed.
2. Pipe network pressure test
   • measure the pressure at the end with a gas point. If it is lower than the rated pressure by more than 20%, the system capacity needs to be reevaluated.
3. economic analysis
   • calculate the loading rate of air compressor (ideal range 70-90%), if long-term <60%, consider configuring frequency conversion model

5. optimization recommendations

1. graded gas supply system
   • high-pressure equipment (>0.7MPa) and low-pressure equipment are supplied separately to reduce throttling losses.
2. waste heat recovery
   • the calorific value of the air compressor accounts for 80-90% of the input power, and the waste heat recovery device can be configured for boiler water preheating
3. intelligent control
   • install intelligent flow controller to realize real-time monitoring of gas consumption and leakage alarm

through the above method, the plant compressed air demand model can be established. It is recommended to review every 2-3 years, especially after process changes or equipment increases or decreases. For new plants, the analogy method can be used to reserve 20-30% of the expansion capacity by referring to the gas consumption data of the same type of plant.