Table 2: Analysis of DEopDED Bleaching
|
Oxygen |
Conventional |
|||
|
Delignification |
Delignification |
|||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
|
Pre-O2 Kappa Number |
29.8 |
28.9 |
- |
- |
|
O2 Delignification, % |
33 |
44 |
- |
- |
|
D 0 Stage Information |
||||
|
Kappa Number to D 0 Stage |
19.9 |
16.1 |
29.8 |
27.5 |
|
Plants using Enzyme |
0 |
0 |
2 |
0 |
|
COD Carryover, kg/ADMt |
9.0 |
6.1 |
12.0 |
7.7 |
|
Na 2SO4 Carryover, kg/ADMt |
6.9 |
10.3 |
8.0 |
9.6 |
|
Retention Time, min. |
40 |
35 |
37 |
36 |
|
Do Stage Temperature, °C |
59 |
58 |
54 |
54 |
|
End pH |
2.7 |
3.2 |
2.7 |
2.5 |
|
ClO 2, kg/ADMt |
13.7 |
16.1 |
21.3 |
22.5 |
|
Kappa Factor |
0.18 |
0.27 |
0.19 |
0.22 |
|
No. |
No. |
No. |
No. |
|
|
D 0 Stage Consistency, Medium |
3 |
1 |
0 |
4 |
|
D 0 Stage Consistency, Low |
4 |
6 |
12 |
6 |
|
D 0 Stage Upflow |
4 |
7 |
8 |
6 |
|
D 0 Stage Upflow/Downflow |
3 |
0 |
4 |
4 |
|
Acid Added |
7 |
5 |
6 |
4 |
|
H 2SO4 |
7 |
5 |
6 |
4 |
|
CO 2 to brownstock |
0 |
1 |
1 |
1 |
|
First Stage Control |
No. |
No. |
No. |
No. |
|
Pre-tower Optical Sensor |
6 |
7 |
12 |
9 |
|
Pre-tower Residual Sensor |
6 |
7 |
12 |
9 |
|
Post-tower Optical |
2 |
2 |
2 |
1 |
|
Post-tower Residual |
0 |
2 |
0 |
0 |
|
Kappa Analyser |
4 |
3 |
7 |
3 |
|
Control to D 0 Brightness |
2 |
2 |
3 |
7 |
|
Control to Eo(p) Brightness |
3 |
2 |
3 |
2 |
|
Control to Eo(p) Kappa Number |
3 |
1 |
5 |
1 |
* Including all oxidizing chemicals used in D
0 and subsequent stages
|
Oxygen |
Conventional |
|||
|
Delignification |
Delignification |
|||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
|
Extraction Stage Information |
||||
|
Eop Kappa Number |
5.0 |
3.1 |
5.0 |
3.4 |
|
Eop Brightness |
56 |
63 |
49 |
61 |
|
End pH |
10.6 |
10.7 |
10.7 |
10.5 |
|
NaOH, kg/ADMt |
17.4 |
21.2 |
20.0 |
25.2 |
|
NaOH/Eq. Cl 2 with Papricycle |
0.39 |
- |
0.25 |
0.40 |
|
NaOH/Eq. Cl 2 without Papricycle |
0.52 |
0.52 |
0.45 |
0.46 |
|
Oxygen Addition, kg/ADMt |
5.5 |
5.0 |
5.2 |
6.6 |
|
H 2O2 Addition, kg/ADMt |
3.5 |
3.0 |
3.1 |
4.5 |
|
Kappa Factor* after Eo(p) Stage |
0.34 |
0.45 |
0.29 |
0.36 |
|
% Delignification after Eo(p) Stage |
76 |
81 |
83 |
87 |
|
∆% Eq. Cl 2 per ∆ Kappa No.** |
0.43 |
0.56 |
0.35 |
0.43 |
|
Retention Time @ pressure, min. |
40 |
15 |
37 |
37 |
|
Temperature, °C |
80 |
76 |
81 |
82 |
|
No. |
No. |
No. |
No. |
|
|
Oxygen Added |
7 |
7 |
12 |
9 |
|
Hydrogen Peroxide Added |
7 |
6 |
10 |
9 |
|
Papricycle® |
2 |
0 |
5 |
3 |
|
Extraction Stage Control |
No. |
No. |
No. |
No. |
|
Kappa Analyser |
2 |
1 |
4 |
1 |
|
Control to end pH |
7 |
6 |
11 |
8 |
|
Control to Eo(p) Brightness |
2 |
4 |
1 |
3 |
|
Control to Eo(p) Kappa Number |
2 |
1 |
4 |
2 |
* Sum of chlorine dioxide in first stage plus oxygen and hydrogen peroxide in extraction - all expressed as % equivalent chlorine on pulp divided by unbleached kappa no.
** All oxidizing chemicals in the D
0 and Eo(p) stages as % equivalent chlorine divided by the change in kappa number (i.e., unbleached kappa no. minus the extracted kappa no.)
|
Oxygen |
Conventional |
|||
|
Delignification |
Delignification |
|||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
|
First ClO 2 Brightening (D1)Stage Information |
||||
|
Retention Time, min. |
154 |
149 |
168 |
149 |
|
Temperature, °C |
75 |
73 |
71 |
70 |
|
Upflow pH |
4.0 |
3.9 |
3.7 |
4.4 |
|
End pH |
3.5 |
3.6 |
3.3 |
3.2 |
|
Brightness, % ISO |
83.7 |
83.4 |
83.9 |
83.0 |
|
ClO 2, kg/ADMt |
10.0 |
9.6 |
11.0 |
12.3 |
|
ClO 2, per Eop kappa, kg/kappa unit |
2.1 |
4.2 |
2.5 |
4.4 |
|
NaOH, kg/ADMt* |
1.2 |
1.6 |
3.6 |
3.1 |
|
H 2SO4, kg/ADMt* |
0 |
7.3 |
0 |
0 |
|
DEopD Kappa Factor |
0.47 |
0.60 |
0.39 |
0.48 |
|
First ClO 2 Brightening (D1)Control Strategy |
No. |
No. |
No. |
No. |
|
Pre- ClO 2 Mixer Optical Sensor |
5 |
2 |
3 |
3 |
|
Pre-tower Optical Sensor |
3 |
5 |
6 |
8 |
|
Pre-tower Residual Sensor |
7 |
7 |
10 |
8 |
|
Control to End of Stage Residual |
5 |
2 |
8 |
3 |
|
Control to Compensated Brightness |
5 |
3 |
8 |
8 |
|
Control to D 1 Brightness |
5 |
7 |
10 |
7 |
|
Control to Upflow pH |
4 |
3 |
1 |
7 |
|
Add NaOH for pH Control |
4 |
2 |
8 |
3 |
|
Add H 2SO4 for pH Control |
0 |
2 |
0 |
0 |
|
Control to End pH |
3 |
3 |
7 |
4 |
|
Antichlor Added |
4 |
1 |
3 |
3 |
SO 2 |
1 |
0 |
1 |
3 |
NaOH |
3 |
1 |
2 |
0 |
* When added
|
Oxygen |
Conventional |
|||||||
|
Delignification |
Delignification |
|||||||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
||||
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
||||
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
||||
|
Second Extraction (E 2)Stage Information |
||||||||
|
NaOH, kg/ADMt (Short Stage)* |
2.0 |
9.6 |
- |
- |
||||
|
NaOH, kg/ADMt (Conv. Stage)** |
4.1 |
5.2 |
5.6 |
6.8 |
||||
|
H 2O2, kg/ADMt, (when used) |
1.4 |
0.5 |
1.4 |
1.7 |
||||
|
Brightness, % ISO |
84.6 |
85.3 |
80.0 |
81.0 |
||||
|
End pH |
10.4 |
10.3 |
10.5 |
10.5 |
||||
|
Retention Time, min. (Short) |
5 |
5 |
- |
- |
||||
|
Retention Time, min. |
68 |
80 |
78 |
62 |
||||
|
Temperature, °C |
77 |
70 |
74 |
75 |
||||
|
No. |
No. |
No. |
No. |
|||||
|
Conventional Stage |
6 |
3 |
12 |
10 |
||||
|
Short Extraction Stage |
1 |
3 |
0 |
0 |
||||
|
Control to End pH |
7 |
6 |
10 |
8 |
||||
|
Stages with H 2O2 |
3 |
3 |
6 |
6 |
||||
* (Dn)D
** DED
|
Oxygen |
Conventional |
|||
|
Delignification |
Delignification |
|||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
|
Second ClO 2 Brightening (D2)Stage Information |
||||
|
Retention Time, min. |
150 |
191 |
176 |
165 |
|
Stage Temperature, °C |
75 |
76 |
78 |
74 |
|
Upflow pH |
4.5 |
4.5 |
4.3 |
4.5 |
|
End pH |
3.8 |
3.9 |
3.4 |
3.9 |
|
Brightness, % ISO |
89.7 |
89.4 |
90.1 |
89.3 |
|
ClO 2, kg/ADMt |
2.1 |
3.5 |
3.2 |
3.7 |
|
Second ClO 2 Brightening (D2)Control Strategy |
No. |
No. |
No. |
No. |
|
Pre-ClO 2 Mixer Optical Sensor |
0 |
2 |
1 |
1 |
|
Pre-tower Optical Sensor |
1 |
2 |
2 |
2 |
|
Pre-tower Residual Sensor |
2 |
4 |
4 |
2 |
|
Control to End of Stage Residual |
6 |
4 |
5 |
5 |
|
Control to Compensated Brightness |
0 |
3 |
1 |
1 |
|
Control to D 2 Brightness |
6 |
7 |
9 |
3 |
|
Control to Upflow pH |
2 |
3 |
3 |
4 |
|
Add NaOH for pH Control |
1 |
3 |
4 |
2 |
|
Add H 2SO4 for pH Control |
1 |
2 |
2 |
0 |
|
Control to End pH |
1 |
5 |
6 |
3 |
|
Antichlor Added |
5 |
6 |
4 |
3 |
SO 2 |
5 |
5 |
3 |
3 |
NaOH |
2 |
1 |
1 |
0 |
|
Oxygen |
Conventional |
|||
|
Delignification |
Delignification |
|||
|
Relative Sequence Chemical Consumption* |
Low |
High |
Low |
High |
|
Final Brightness |
89.7 |
89.4 |
90.1 |
89.3 |
|
Number of ECF Bleach Plants |
7 |
7 |
12 |
10 |
|
Overall Chemical Consumption |
||||
|
ClO 2, kg/ADMt |
25.8 |
29.2 |
34.9 |
37.8 |
|
O 2, kg/ADMt |
5.5 |
5.0 |
5.2 |
6.6 |
|
H 2O2, kg/ADMt |
4.1 |
3.3 |
3.8 |
5.5 |
|
NaOH, kg/ADMt |
22.0 |
27.9 |
27.5 |
30.9 |
|
Sequence Kappa Factor* |
0.51 |
0.66 |
0.41 |
0.51 |
|
Bleaching Cost, Cdn $/ADMt** |
37.29 |
41.92 |
48.26 |
53.57 |
|
Efficiency, Cdn $/Kappa No. |
1.87 |
2.63 |
1.62 |
1.96 |
|
|
||||
* Sum of chlorine dioxide in all stages plus oxygen and hydrogen peroxide in extraction stages - all expressed as % equivalent chlorine on pulp divided by unbleached kappa no.
**Cdn $: ClO
Optimization Summary - Oxygen Delignified Pulps
Relative Sequence Chemical Consumption |
Low |
High |
|
Category |
Rating (out of 5) |
Rating (out of 5) |
Minimize Bleaching Cost |
4.4 |
3.9 |
Minimize ClO 2 |
4.3 |
4.0 |
Maximize Brightness |
3.6 |
4.3 |
Achieve Low Kappa Number |
3.4 |
3.4 |
Minimize AOX |
3.3 |
2.6 |
Minimize Shives |
3.3 |
3.6 |
Maximize Pulp Strength |
2.4 |
2.9 |
Minimize TOX in Pulp |
2.4 |
2.9 |
Compensate for Short Sequence |
2.0 |
2.9 |
Compensate for Short Retention |
2.0 |
2.6 |
Optimization Summary - Conventionally Delignified Pulps
Relative Sequence Chemical Consumption |
Low |
High |
|
Category |
Rating (out of 5) |
Rating (out of 5) |
Minimize ClO 2 |
4.4 |
4.2 |
Minimize Bleaching Cost |
4.3 |
4.1 |
Minimize Shives |
4.3 |
3.5 |
Minimize AOX |
3.5 |
3.7 |
Maximize Final Brightness |
3.2 |
3.3 |
Compensate for Short Retention |
3.2 |
2.1 |
Achieve Low Kappa Number |
3.0 |
2.8 |
Compensate for Short Sequence |
2.9 |
4.0 |
Maximize Pulp Strength |
2.8 |
2.1 |
Minimize TOX in Pulp |
2.7 |
3.3 |
Optimization Rating Scheme
1 - Strongly disagree
2 - Disagree
3 - No opinion/not applicable
4 - Agree
5 - Strongly agree