Structure and arrangement of perforated plates for uniform flow distribution in an electrostatic precipitator

Figures & data

Table 1. Structure of the perforated plate

Porosity (%)	Number of holes/m^2 plate area	Diameter of hole (m)	Thickness (mm)
50	0.012	0.074	5
	0.046	0.037	5
	0.104	0.025	3, 4, 5
	0.185	0.019	5
	0.289	0.015	5
40	0.012	0.066	5
	0.046	0.033	5
	0.104	0.022	5
	0.185	0.017	5
	0.289	0.013	5
30	0.012	0.058	5
	0.046	0.029	5
	0.104	0.019	5
	0.185	0.014	5
	0.289	0.012	5

Figure 1. Schematic and picture of the duct system

Table 2. Dimensions of the lab-scale electrostatic precipitator

Items			Dimensions
Inlet Duct	Height		0.250 m
	Width		0.250 m
Diffuser	Inlet height		0.250 m
	Inlet width		0.250 m
	Exit height		0.875 m
	Exit width		0.700 m
	Length		0.600 m
	Divergency angle	Vertical (2α)	92 °
		Horizontal (2γ)	74 °
Body	Width		0.700 m
	Length		2.000 m
Contractor	Inlet height		0.875 m
	Inlet width		0.700 m
	Exit height		0.250 m
	Exit width		0.250 m
Outlet Duct	Height		0.250 m
	Width		0.250 m

Figure 2. Pictures of the lab-scale electrostatic precipitator

Figure 3. Schematic diagram of the diffuser, perforate plate and sampling grid

Table 3. Duct test results depending on the number of holes of the perforated plate with a thickness of 5 mm and a porosity of 50%

Number of holes	Inlet velocity (m/s)	Pressure loss (Pa)	Standard error	Pressure loss coefficient	Discharge coefficient
0.012 holes/m^2 area	6	89.88	0.419	4.161	0.490
	9	203.13	0.509	4.180	0.489
	12	367.13	0.718	4.249	0.485
0.046 holes/m^2 area	6	66.63	0.436	3.084	0.569
	9	146.88	0.436	3.022	0.575
	12	264.25	0.385	3.058	0.572
0.104 holes/m^2 area	6	55.75	0.177	2.581	0.622
	9	125.24	0.287	2.577	0.623
	12	227.76	0.593	2.636	0.616
0.185 holes/m^2 area	6	54.88	0.307	2.541	0.627
	9	119.76	0.377	2.464	0.637
	12	212.14	0.548	2.455	0.638
0.289 holes/m^2 area	6	51.63	0.436	2.390	0.647
	9	108.36	0.433	2.230	0.670
	12	192.76	0.456	2.231	0.669

Table 4. Duct test results depending on the number of holes of the perforated plate with a thickness of 5 mm and a porosity of 40%

Number of holes	Inlet velocity (m/s)	Pressure loss (Pa)	Standard error	Pressure loss coefficient	Discharge coefficient
0.012 holes/m^2 area	6	181.38	0.462	8.397	0.345
	9	401.75	0.931	8.266	0.348
	12	728.88	1.147	8.436	0.344
0.046 holes/m^2 area	6	132.38	0.469	6.128	0.404
	9	298.06	0.728	6.133	0.404
	12	544.38	1.075	6.301	0.398
0.104 holes/m^2 area	6	119.75	0.355	5.544	0.425
	9	261.88	0.697	5.388	0.431
	12	472.25	0.709	5.466	0.428
0.185 holes/m^2 area	6	111.50	0.436	5.162	0.440
	9	248.17	0.714	5.106	0.443
	12	448.25	1.000	5.188	0.439
0.289 holes/m^2 area	6	102.58	0.357	4.749	0.459
	9	231.63	0.400	4.766	0.458
	12	402.50	0.536	4.659	0.463

Table 5. Duct test results depending on the number of holes of the perforated plate with a thickness of 5 mm and a porosity of 30%

Number of holes	Inlet velocity (m/s)	Pressure loss (Pa)	Standard error	Pressure loss coefficient	Discharge coefficient
0.012 holes/m^2 area	6	382.27	0.437	17.698	0.238
	9	837.88	0.742	17.240	0.241
	12	1524.50	1.424	17.645	0.238
0.046 holes/m^2 area	6	299.63	0.799	13.872	0.268
	9	663.13	1.539	13.645	0.271
	12	1201.25	1.815	13.903	0.268
0.104 holes/m^2 area	6	257.54	0.869	11.923	0.290
	9	577.13	1.404	11.875	0.290
	12	1061.50	1.625	12.286	0.285
0.185 holes/m^2 area	6	241.18	0.850	11.166	0.299
	9	536.25	1.331	11.034	0.301
	12	982.25	1.728	11.369	0.297
0.289 holes/m^2 area	6	236.51	0.692	10.950	0.302
	9	489.38	1.237	10.069	0.315
	12	925.88	1.690	10.716	0.305

Figure 4. Discharge coefficient depending on the number of holes in the perforated plate with a thickness of 5 mm

Table 6. Duct test results depending on the plate thickness with a porosity of 50% and 0.104 holes/m² plate area

Thickness (mm)	Inlet velocity (m/s)	Pressure loss (Pa)	Standard error	Pressure loss coefficient	Discharge coefficient
5	6	55.75	0.177	2.581	0.622
	9	125.24	0.287	2.577	0.623
	12	227.76	0.593	2.636	0.616
4	6	51.75	0.275	2.396	0.646
	9	121.10	0.370	2.492	0.634
	12	223.13	0.551	2.582	0.622
3	6	51.50	0.287	2.384	0.648
	9	121.10	0.370	2.492	0.634
	12	224.38	0.446	2.597	0.621

Figure 5. Discharge coefficient depending on the porosity of the perforated plate with a thickness of 5 mm and 0.104 hole/m² plate area

Figure 6. Discharge coefficient depending on the thickness of the perforated plate with a porosity of 50% and 0.104 hole/m² plate area

Figure 7. Velocity distribution without the perforated plate (a) and with one perforated plate

Table 7. Summary of velocity distribution with two perforated plates at the interval of less than 0.2 m

	A, B	B, C	C, D	B, D	C, E	D, F
Velocity RMS%	67.89	47.90	44.45	33.86	33.71	40.52
Mean velocity (m/s)	1.209	1.172	1.178	1.178	1.14	1.01
Inlet velocity (m/s)	11.27	11.46	11.58	11.54	11.64	11.49
Standard error for mean velocity (m/s)	0.260	0.177	0.166	0.126	0.122	0.130

Figure 8. Velocity distribution with two perforated plates at the interval of less than 0.2 m

Table 8. Summary of velocity distribution with two perforated plates at the interval exceeding 0.2 m

	A, D	A, E	A, F	B, E	B, F	C, F
Velocity RMS%	40.44	36.60	34.05	28.49	29.32	30.54
Mean velocity (m/s)	1.16	1.17	1.12	1.21	1.16	1.24
Inlet velocity (m/s)	11.41	11.44	11.15	11.62	11.43	11.72
Standard error for mean velocity (m/s)	0.148	0.135	0.120	0.109	0.108	0.120

Figure 9. Velocity distribution with two perforated plates at the interval exceeding 0.2 m

Table 9. Summary of velocity distribution by adding the 1st perforated plate to DF and CE configurations, respectively

	A, D, F	C, D, F	A, C, E	B, C, E
Velocity RMS%	22.86	22.66	23.74	22.16
Mean velocity (m/s)	1.225	1.243	1.252	1.273
Inlet velocity (m/s)	11.27	11.35	11.40	11.55
Standard error for mean velocity (m/s)	0.089	0.089	0.083	0.086

Figure 10. Velocity distribution by adding the 1st perforated plate to DF and CE configurations, respectively

Table 10. Summary of velocity distribution by adding the 2nd perforated plate to AF and AE configurations, respectively

	A, B, F	A, E, F	A, B, E	A, D, E
Velocity RMS%	20.64	30.53	20.84	29.94
Mean velocity (m/s)	1.22	1.24	1.23	1.27
Inlet velocity (m/s)	11.19	11.30	11.30	11.45
Standard error for mean velocity (m/s)	0.079	0.120	0.081	0.120

Figure 11. Velocity distribution by adding the 2nd perforated plate to AF and AE configurations, respectively

Table 11. Summary of velocity distribution by adding the 3rd perforated plate to AB and BD configurations, respectively

	A, B, D	A, B, F	B, D, E	B, D, F
Velocity RMS%	27.52	20.64	25.38	21.72
Mean velocity (m/s)	1.21	1.22	1.27	1.26
Inlet velocity (m/s)	11.27	11.19	11.57	11.44
Standard error for mean velocity (m/s)	0.105	0.079	0.102	0.087

Figure 12. Velocity distribution by adding the 3rd perforated plate to AB and BD configurations, respectively