# Effect of Venturi Structures on the Cleaning Performance of a Pulse Jet Baghouse
## 3 Results and Discussion
This result was consistent with the regular pattern related to the influence of different pulsing air pressure values (\(P_{Pu}\)) on the peak pressure (\(P_{Pk}\)), namely, for long filter bags, when the cleaning airflow passed through the upper half of the filter bag, due to the very high airflow velocity, the time of the cleaning airflow reaching the \"top\" point was similar under different pulsing air pressures, which meant the peak pressure arrival time at the \"top\" point tended to be the same. However, in the lower half of the filter bag, under different pulsing air pressures, the energy attenuation of the cleaning airflow was different, so that the peak pressure arrival time values were different. In addition, when the pulsing air pressure was 0.4 MPa and 0.5 MPa, the difference between the peak pressure arrival time at the three measuring points was small. Additionally, it was observed that the higher the pulsing air pressure, the greater the consumption of compressed air, and the higher the energy consumption of the cleaning bag. Moreover, high pulsing air pressure values caused excessive cleaning of the filter bag, destroying the initial layer of dust cake and reducing the filtration efficiency of the filter bag. Therefore, when selecting the pulsing air pressure, the relationship between the cleaning effect, the energy consumption of the pulse jet cleaning device, and the filtration efficiency of the filter bag should be systematically considered. In this investigation, a pulsing air pressure value of 0.4 MPa was selected to carry out the follow-up experimental study. According to Figure 7, at a constant pulsing air pressure (\(P_{Pu}\)) value of 0.4 MPa, the effect of different pulsing air injection times (100, 150, and 200 ms) on the peak pressure was not significant. This figure shows that applying the three injection times previously mentioned, the peak pressure of the filter bag was similar in the two measuring points labeled as \"top\" and \"middle\", respectively. However, these values were significantly different at the measuring point labeled as \"bottom\". On the other hand, Figure 8 shows that the peak pressure arrival time (\(t_{R}\)) increased with increasing pulsing air injection time values (\(t_{P}\)), and the difference between the peak pressure arrival time (\(t_{R}\)) at the same measuring point increased when the distance between the measuring points and the bag mouth increased. This indicates that the influence of the pulsing air injection time (\(t_{P}\)) on both the peak pressure (\(P_{Pk}\)) and the peak pressure arrival time (\(t_{R}\)) was not the same. This phenomenon may be explained by the fact that, at a constant value of the compressed pulsing air pressure, by increasing the  
Figure 5: Effect of the pulsing air pressure on peak pressure of filter bag. pulsing air injection time, the amount of compressed air injected into the filter bag also increases; in addition, the peak pressure arrival time at the \"top\" measuring point was less than 40 ms, which was significantly smaller than the injection time of the compressed pulsing air set in the experiment. This indicates that the cleaning airflow pressure at the \"top\" measuring point had reached its peak value before the end of the pulsing air injection. Therefore, the compressed airflow injected between the peak pressure arrival time and the end of the pulsing airflow injection had no significant influence on the peak pressure and the peak pressure arrival time at the point labeled as \"top\". On the other hand, with the increase of the injection time, the total flow volume of the primary airflow increased, which in turn increased the total flow volume of the secondary airflow and ultimately led to the increase of the total amount and duration of the cleaning airflow.