Calculation of conveying gas consumption of powder air compressor

The calculation of the gas volume conveyed by the powder air compressor needs to consider the material characteristics, conveying distance, pipeline parameters and process requirements. The following are the key calculation steps and core parameter analysis:

determination of 1. basic parameters

1. conveying capacity (mass flow)
   • determine the mass of powder to be delivered per unit time (e. g., tons/hour) according to production requirements, which is recorded as m (unit: kg/h).
   • Example: If 5 tons of powder need to be transported per hour, m = 5000 kg/h.
2. Powder bulk density (& rho; B)
   • the density of the powder in the natural accumulation state (unit: kg/m & sup3;) shall be obtained through experiments or material manuals.
   • Key Points: The bulk density affects the volume ratio of powder in the conveying pipeline, which in turn affects the efficiency of pneumatic conveying.
3. Solid-gas ratio (μ)
   • the ratio of powder mass to gas mass (unit: kg powder/kg air), reflecting the conveying concentration.
   • Scope: dilute phase conveying is usually 1 & sim;10, dense phase conveying can reach 10 & sim;50.
   • Selection basis powder fluidity, pipe length and pressure loss requirements.

2. gas volume flow calculation

1. theoretical volume flow rate (Q theory)

   • calculate the required gas mass flow rate based on the mass flow rate and the solid-gas ratio:

m gas = μm

• assuming an air density of & rho; gas (about 1.225kg/m3 in the standard state), the theoretical volumetric flow rate is:

Q theory = & rho; gas m = μ & sdot;& rho; gas m

• unit conversion: If the required unit is m3/min, Q theory = 60 & sdot;μ & sdot;& rho; Gas m.

2. Actual volume flow (Q actual)

   • considering pipeline leakage, valve loss and other factors, it is necessary to introduce a safety factor K (usually 1.1 & sim;1.3):

Q actual = K & sdot;Q theory

• key Points: The safety factor shall be adjusted according to the system tightness, conveying distance and powder characteristics.

3. conveying pressure and compressor selection

1. delivery pressure (P)
   • pipeline resistance, lifting height and terminal equipment resistance need to be overcome, usually determined by empirical formulas or experiments.
   • Simplified calculation:
     • horizontal pipeline pressure loss & Delta;P horizontal & prop;DL & sdot;v2 & sdot;& rho; mix (L is pipe length, v is flow rate, D is pipe diameter, & rho; mix is mix density).
     • Vertical Lift Pressure & Delta;P Vertical = & rho; Mix & sdot;g & sdot;h(h is lift height).
   • Total pressure: P = P atmospheric & Delta;P horizontal & Delta;P vertical & Delta;P terminal.
2. Discharge capacity of compressor (Q compressor)

   • the change in gas volume after compression is considered (according to the ideal gas state equation PV = nRT):

Q Compressor = P Exhaust Q Actual & sdot;P Intake

• simplifying assumptions: If the intake pressure is atmospheric pressure P atmosphere and the exhaust pressure is P, then:

Q Compressor = Q Actual & sdot;PP Atmosphere

• unification of units ensure that the pressure unit is consistent (e. g. bar or MPa).

4. Key Parameter Optimization Recommendations

1. solid-gas ratio selection
   • A high solid-to-gas ratio can reduce gas usage, but requires higher pressure and more complex equipment (e. g. rotary valves, delivery tanks).
   • The low solid-gas ratio simplifies the system, but the energy consumption is high, and the economy and efficiency need to be balanced.
2. flow rate control
   • the powder conveying flow rate is usually 10 & sim;30 m/s. Sedimentation (too low flow rate) or excessive wear (too high flow rate) should be avoided.
   • Calculation Reference: According to pipe diameter D and volume flow Q, flow rate v = & pi;D24Q.
3. Pipeline Design
   • reduce elbows, valves and other local resistance components, reduce pressure loss.
   • Pipe diameter selection needs to take into account the flow rate and pressure loss, and the optimal value is usually determined by iterative calculation.

5. summary formula

the simplified calculation formula for the air volume (compressor displacement) required for powder air compressor transportation is:

Q compressor = 60 & sdot;μ & sdot;& rho; gas & sdot;Pm & sdot;K & sdot;P atmosphere

parameter Description:

• m: Powder mass flow (kg/h);
• k: safety factor (1.1~1.3);
• μ: solid-gas ratio (kg powder/kg air);
• & rho; air: air density (kg/m & sup3;);
• p: delivery pressure (absolute pressure, unit shall be consistent with P atmosphere);
• P atmosphere: atmospheric pressure (usually 1 bar).

Precautions:

• the actual calculation needs to be corrected in combination with the powder characteristics (such as particle size, humidity, fluidity);
• for complex systems, it is recommended to verify the parameter selection through CFD simulation or experiment.