Industrial Green Liquor Implementation: Startup Implementation ...
Industrial Green Liquor Implementation: Startup, Startup Monitoring, and Results Ved Naithani,1 Lucian Lucia,1 Peter Hart,1,2 Sujit Banerjee, j ,1,3 & Hasan Jameel,,1 Garyy Colson2 1North
Carolina State University 2MeadWestvaco
3Institute
of Paper Science and Technology, Georgia Institute of Technology
Motivation for novelty http://www.youtube.com/watch?v= bVVsDIv98TA
300
250
C h ile Ja p an A u st r a l ia S outh A fri ca P o la n d N ew Z e a la n d S p a in C ze ch R ep A u st r ia Tur k e y R oma n ia B e la r us P or tu ga l
R u ss
B r azi l ia n F e d S w ed en In d o n e s ia F i n la n d M a la y s ia G er m an y F r an c e In d ia
U SA C an a da C h in a
Milliions of Cu ubic Meteers
US #1 Producer of Wood as a Material 450
400
350
Percent of Total World Production
200
150
100
50
0 100 90 80 70 60 50 40 30 20 10 0
U.S. Forest Products Consumption (production plus (p p net imports) p ) 600
Million tons, dry we eight
Net Imports 500
Paper& paperboard Composites production
400
Lumber & miscellaneous 0.9% per year increase
300 1.9% per year increase
200 Paper/paperboard p p p increases most
100 0 1960
1970
1980
1990
2000
2010
2020
2030
2040
2050
Changes at US Pulp Mills • Mill closures • Low return on investment • Foreign competition
Kimberly Clarke Terrace Bay Mill
• Recent upswing in pulp prices p ces • Improve wood use at front end of operations
Quiz • The US total wood production is approximately how far in excess of its nearest competitor (as of 2005)? (a) 10% (b) 25% (c) 50% (d) 100% • The US forest commodity that will be experiencing the greatest growth is: (a) composites (b) paper/paperboard (c) lumber • O One off the h greatest threats h to the h US fforest products industry is: (a) foreign competition (b) lack of new capital investments (c) pulp prices
Green Liquor Impregnation: What are we trying to do? US Southern wood chips when pretreated green liquor q ((GL), ), a rich and recyclable y with g hydrosulfide source, prior to kraft pulping provide a faster delignification g and can p decrease the overall consumption of pulping p fiber strength g chemicals as well as improve properties* *Sjoblom, j , K.,, Mjoberg, j g, J. and Hartler,, N. Paperi p ja j Puu 65 ((4)) 227: ((1983)) Kirkman, A. G.; Andrews, E. K.; Chang, H.-m. AIChE Symposium Series (1984), 80(232), 66-73. 2. Andrews, E. K.; Chang, Hou-Min; Eckert, R. C. Journal of Wood Chemistry and Technology (1985), 5(4), 431-50. Olm, L., Backstrom, M. and Tormund, D. Journal of pulp and paper science 22(7): J241 (1996);
Green Liquor Pretreatment • Concept of “repurposed repurposed mill” mill by Phillips (NCSU) • Ethanol production • Integrated I t t d mill ill conceptt • Perhaps most feasible biorefinery concept for biofuels?
Proposed Qualitative Theorem of Pulp Economics • Process P1 ((0 – 1)) where 0 totallyy unoptimized p process & 1 is totally optimized (normalized to full functionality) • Product P2 (0 – 1) • Environment E1 (0 – 1) • Energy E2 (0 – 1) • Economics E3 (0 – 1) • Thus, P1P2 + E1E2 2E3 • For GL impregnation, I have calculated a qualitative economic return of 0.65 (with my assumptions of each variable)
Principles • Offload Offl d recovery (kil (kiln)) off WL production d ti • Improve p p pulpability p y of chips p • Improve final pulp qualities • Improve paper machine runnability • Reduce R d energy ffootprint t i t off the th mill ill
TARGET MILL • Evadale, TX • No. 5 Di Digester t • Working g with Peter Hart & Gary Colson Property of MWV Evadale, not to be used without express written permission
Mill Results • Mill ran GL addition in IV over one year from 40% (high, replaced 10% of WL EA by 40% GL) – 10% (low, replaced 10% of WL EA by 10% GL) • Qualitative evaluation based on observation of secondary knotter • Increased rejects seem to correspond to increased green liquor substitution
Mill Results Results, continued • Last attempt p at 20% substitution, rejects were unmanageable • Cut green liquor off and rejects returned to normal within 12 hours hours. • No noticeable change in residual alkali • Perhaps chip penetrant may reduce rejects
Scaling • Operated p at 40% substitution level for 15 day y period in May, 2010 – plugged bottom screen of high pressure feeder and in-line drainer baskets • Weekly inspection of in-line drainer baskets was useful for scaling rate evaluation • Have circulated EDTA in chip feed system to enable operation until a scheduled outage • Increase in Buckman anti-scale product dosage from 1.0 to 1.5 pounds per ton has been effective e ect e ttreatment eat e t
Scaling, g, continued •
Installed high pressure feeder with Andritz UniGrid™ during May outage Grid
•
Incremental specialty chemical cost about the same as kiln energy savings
•
Operated at 20% y substitution for a 10-day period prior to May outage
•
Significantly increased scale noticed on impregnation vessel during May outage inspection
•
Currently, C tl h have h handle dl on controling scale
Okay, off to the lab!
http://psychologytoday.com/blog/lifestyle-design/201003-science-homeschoolcultrure
EXPERIMENTAL PROCEDURES Experimental procedure: WL /GL-MCC pulping divided into four steps: Impregnation Stage (1) White liquor charge is 60% of the total EA-16.5% or 18.9%EA Liquor to Wood ratio - 3.5:1 Max.temperature-265 0F (130 0C) Time to hold at this temp-30 min Co-Current Stage (2) White liquor charge is 20% of the total EA-16.5% Liquor to Wood ratio - 4:1 Max.temperature-335 0F (168 0C) Time to temperature (130 to 168 0C)-20 min Time to hold at this temp-50 min
EXPERIMENTAL PROCEDURES, continued ti d Extraction Stage-1 (3) White Liquor charge is 10% of the total EA-16.5% or 18.9%EA Withdraw 1000ml of BL and add 10% WL makeup with weak BL to 1000ml Temperature drops to ~140C Time to raise the temp to -335F (168C)-15 min Time to hold at this temp-105 min Extraction Stage-2 (4) White Liquor charge is 10% of the total EA-16.5% or 18.9%EA Withdraw 1000ml of Black Liquor q and add 10% WL makeup p with weak BL to 1000ml Temperature drops to ~140 0C Time to raise the temp to 335F (168C)-15 min Time to hold at this temp-105 min
Three (3) Key Lab Results MCC PULPING RESULTS FIRST : By reducing the %EA (WL) and increasing GL to maintain total TTA, the lignin content goes up significantly and so do the rejects. In the substitution case, the EA from the WL is CRITICAL for maintaining acceptable kappa and rejects levels because of its delignification g capacity p y and p potentially yp penetration. The total TTA arising g from both WL & GL is not what controls these latter quantities SECOND : Hi h green liliquor charge High h addition dditi (40% GL, GL att 95% WL EA charge) h ) can llower th the kkappa number, but increase in rejects level cannot be avoided (FOR OVERSIZE CHIPS ONLY) THIRD : 1K 1.Keeping i Whit White liliquor charge h same as th thatt off b baseline li (16 (16.5%EA) 5%EA) and d adding ddi green liquor (5-20% of EA charge), lowers the kappa number as well as the rejects level (Accept chips 2-8 mm in thickness ONLY) 2.Keeping White liquor charge same as that of baseline (16.5% EA) and adding green liquor (5-20% of EA charge), lowers the kappa number, but not the rejects level. (Oversize chips>8 mm in thickness ONLY)
Result #1 • By reducing the %EA (WL) and increasing GL to maintain total TTA, the lignin content goes up significantly and so do the rejects (ACCEPT CHIPS DONE HERE) • In the substitution case, the EA from the WL is CRITICAL for maintaining acceptable kappa and rejects levels because of its delignification capacity and penetration (OVERSIZE CHIPS HERE) • The total TTA arising from both WL & GL is not what h t controls t l th these llatter tt quantities titi (OVERSIZE AGAIN)
Result #1,, continued MCC SW pulping (Accept chips)
Pulping process Baseline (Screened chips)
MCC pulping_16.5% EA-100%WL-Baseline
Screened Yield%
Kappa Number Rejects%
Reject kappa Number
44.1
25.3
0.7
65.0
45.3
33.9
1.0
72.3
45.1
40.4
1.5
-
46.1
45.4
1.7
81.2
45.3
33.9
1.0
-
44.4
28.2
0.8
-
43.3
24.4
0.6
69.6
SUBSTITUTION: I-A
I-B
I-C
MCC pulping-95%-WL-substituted GL5%16.5%EA-25%S-168C MCC p pulping-90%-WL-substituted p g GL10%16.5%EA-25%S-168C MCC pulping-85%-WL-substituted GL15%16.5%EA-25%S-168C
ADDITION: II-A (same as I-A)
II-B
II-C
MCC pulping-95%-WL-substituted GL5%16.5%EA-25%S-168C MCC pulping-95%WL-Added GL10%-16.5%EA25%S-168C MCC pulping-95%WL-Added GL15%-16.5%EA25%S-168C (5% WL is replaced by 15% GL)
Result #1, #1 continued •
In the addition case, it is evident that each 1% absolute increment from the baseline total TTA produces a decrement of about 4-5 kappa units and 0 2% absolute points rejects level decrease 0.2%
•
The screened yield does go down which is not surprising. At 10% GL substitution (19.7% total TTA), the overall kappa, rejects, and yield are roughly the same. same
•
The baseline kappa of 25.3 may theoretically be achieved at about 20.3% total TTA or 13.2% GL substitution ((each 1% of GL = 0.19% TTA))
•
Reject response follows a linear trend with the total TTA charge
Result #2 MCC-SW PULPING (Oversize chips) Pulping Process MCC pulping_16.5% pulping 16 5% EA_25S-168CEA 25S 168C (Screened chips) Baseline MCC pulping_16.5% EA_25%S-168COversize-Baseline
Screened Yield%
Kappa Number
Rejects%
Reject kappa Number
44.1
25.3
0.7
65.0
43.9
27.9
0.8
87.0
43.1
29.9
0.9
82.3
43.3
31.2
1.0
-
43.4
38.2
1.1
91.2
43.1
41.2
1.5
84.3
44.0
20.0
0.4
-
43.9
21.9
0.5
79.7
44.7
24.9
0.9
84.3
44.8
36.4
1.0
-
SUBSTITUTION ((OVERSIZE CHIPS): ) MCC pulping-95%WL-Sub GL5%16.5%EA-25%S-168C MCC pulping-90%WL-Sub GL10%16.5%EA-25%S-168C MCC pulping-85%WL-Sub GL15%16.5%EA-25%S-168C MCC pulping-80%-WL-substituted GL20%-16.5%EA-25%S-168C ADDITION (OVERSIZE CHIPS) CHIPS): MCC pulping-95%-WL-Added GL40%16.5%EA-25S-168C MCC pulping-90%-WL-Added GL40%16.5%EA-25S-168C 16.5%EA 25S 168C MCC pulping-85%-WL-Added GL40%16.5%EA-25S-168C MCC pulping-80%-WL-Added GL40%16.5%EA-25S-168C
Result #2, continued • High green liquor charge (40% GL) can lower the kappa number, but increase in rejects level cannot be avoided for oversize chips • Did nott find fi d the th kappa k numbers b equivalent i l t to t the th baseline pulp and higher rejects level in the GL substitution (Oversize chips>8 mm thickness) – 85% WL EA charge?
Result #3 PULPING OF ACCEPT AND OVERSIZE CHIPS WHILE MAINTAINING WL CHARGE SAME AS BASELINE =16.5% AND ADDING GL 5-15% IN THE COOKING LIQUOR – significant TTA increase Kappa Number
Pulping Process
MCC -17.4% EA-25%S95%WL-sub GL5%
MCC -18.4% EA-25%S90%WL-sub GL10%
MCC -19.4% EA-25%S85%WL-sub GL15%
MCC-16.5% EA-25%S100%WL-Baseline
Screen chips
Over size chips
Screened Yield
Reject kappa
Rejects
Screen
Over size
Screen
chips
chips
chips
Number
Over size chips
Screen chips
Over size chips
24 5 24.5
27 7 27.7
43 3 43.3
43 1 43.1
05 0.5
1 20 1.20
84 5 84.5
89 8 89.8
21.8
29.2
43.2
43.5
0.6
1.50
74.9
92.9
22.2
25.7
43.1
43.2
0.6
1.70
78.1
88.7
25.3
27.9
43.3
43.5
0.7
0.90
65.0
87.0
Result #3, continued MCC SW PULPING WITH ACCEPT AND OVERSIZE CHIPS KEEPING WL CHARGE 16.5% AND ADDING GL 5-15% IN THE COOKING LIQUOR
• Kappa appa number u be was as co comparable pa ab e to o base baseline e pulps while rejects level was higher when using oversize chips (In case of 19.4% EA-85%WL15%GL charge). • It shows that if we take the same white liquor charge (16.5%EA) ( % ) and keep on increasing the GL charge (TTA increase) there will be an increase in rejects level level, but declining kappa number.
INFLUENCE OF IMPREGNATION TIME ON ACCEPTED AND OVERSIZE SOFTWOOD CHIPS
Pretreatment time has an influence on the accept chips. The pretreatment profile effects the final kappa number (the more impregnation time, the lower the kappa number and rejects%) of the pulp
(Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into screened chips at 130C)
INFLUENCE OF IMPREGNATION TIME ON ACCEPT AND OVERSIZE CHIPS,, continued
Pretreatment time has influence on the MCC pulping on the oversize chips. The pretreatment profile effects the final kappa number (the more impregnation time, the lower the kappa number) of the pulp, but %rejects was not decreased!
(Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into oversize chips at 130C)
INFLUENCE OF IMPREGNATION TIME ON ACCEPT AND OVERSIZE SOFTWOOD CHIPS,, final
The accept chips (2-6 mm) were 100% impregnated, but the oversize chips were not 100% impregnated and have spots uncooked. Thus, rejects level is a real issue with oversize chips
Oversize chips
Accept chips
[Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into accept and oversize chips after pulping at 168C]
CONCLUSIONS • Energy benefits are clear • EA is very important • Penetration in cooking is KEY to success • Oversized chips pose an impediment to success; penetration must be dealt with in a logical manner • Scale can be managed
Carolina State University 2MeadWestvaco
3Institute
of Paper Science and Technology, Georgia Institute of Technology
Motivation for novelty http://www.youtube.com/watch?v= bVVsDIv98TA
300
250
C h ile Ja p an A u st r a l ia S outh A fri ca P o la n d N ew Z e a la n d S p a in C ze ch R ep A u st r ia Tur k e y R oma n ia B e la r us P or tu ga l
R u ss
B r azi l ia n F e d S w ed en In d o n e s ia F i n la n d M a la y s ia G er m an y F r an c e In d ia
U SA C an a da C h in a
Milliions of Cu ubic Meteers
US #1 Producer of Wood as a Material 450
400
350
Percent of Total World Production
200
150
100
50
0 100 90 80 70 60 50 40 30 20 10 0
U.S. Forest Products Consumption (production plus (p p net imports) p ) 600
Million tons, dry we eight
Net Imports 500
Paper& paperboard Composites production
400
Lumber & miscellaneous 0.9% per year increase
300 1.9% per year increase
200 Paper/paperboard p p p increases most
100 0 1960
1970
1980
1990
2000
2010
2020
2030
2040
2050
Changes at US Pulp Mills • Mill closures • Low return on investment • Foreign competition
Kimberly Clarke Terrace Bay Mill
• Recent upswing in pulp prices p ces • Improve wood use at front end of operations
Quiz • The US total wood production is approximately how far in excess of its nearest competitor (as of 2005)? (a) 10% (b) 25% (c) 50% (d) 100% • The US forest commodity that will be experiencing the greatest growth is: (a) composites (b) paper/paperboard (c) lumber • O One off the h greatest threats h to the h US fforest products industry is: (a) foreign competition (b) lack of new capital investments (c) pulp prices
Green Liquor Impregnation: What are we trying to do? US Southern wood chips when pretreated green liquor q ((GL), ), a rich and recyclable y with g hydrosulfide source, prior to kraft pulping provide a faster delignification g and can p decrease the overall consumption of pulping p fiber strength g chemicals as well as improve properties* *Sjoblom, j , K.,, Mjoberg, j g, J. and Hartler,, N. Paperi p ja j Puu 65 ((4)) 227: ((1983)) Kirkman, A. G.; Andrews, E. K.; Chang, H.-m. AIChE Symposium Series (1984), 80(232), 66-73. 2. Andrews, E. K.; Chang, Hou-Min; Eckert, R. C. Journal of Wood Chemistry and Technology (1985), 5(4), 431-50. Olm, L., Backstrom, M. and Tormund, D. Journal of pulp and paper science 22(7): J241 (1996);
Green Liquor Pretreatment • Concept of “repurposed repurposed mill” mill by Phillips (NCSU) • Ethanol production • Integrated I t t d mill ill conceptt • Perhaps most feasible biorefinery concept for biofuels?
Proposed Qualitative Theorem of Pulp Economics • Process P1 ((0 – 1)) where 0 totallyy unoptimized p process & 1 is totally optimized (normalized to full functionality) • Product P2 (0 – 1) • Environment E1 (0 – 1) • Energy E2 (0 – 1) • Economics E3 (0 – 1) • Thus, P1P2 + E1E2 2E3 • For GL impregnation, I have calculated a qualitative economic return of 0.65 (with my assumptions of each variable)
Principles • Offload Offl d recovery (kil (kiln)) off WL production d ti • Improve p p pulpability p y of chips p • Improve final pulp qualities • Improve paper machine runnability • Reduce R d energy ffootprint t i t off the th mill ill
TARGET MILL • Evadale, TX • No. 5 Di Digester t • Working g with Peter Hart & Gary Colson Property of MWV Evadale, not to be used without express written permission
Mill Results • Mill ran GL addition in IV over one year from 40% (high, replaced 10% of WL EA by 40% GL) – 10% (low, replaced 10% of WL EA by 10% GL) • Qualitative evaluation based on observation of secondary knotter • Increased rejects seem to correspond to increased green liquor substitution
Mill Results Results, continued • Last attempt p at 20% substitution, rejects were unmanageable • Cut green liquor off and rejects returned to normal within 12 hours hours. • No noticeable change in residual alkali • Perhaps chip penetrant may reduce rejects
Scaling • Operated p at 40% substitution level for 15 day y period in May, 2010 – plugged bottom screen of high pressure feeder and in-line drainer baskets • Weekly inspection of in-line drainer baskets was useful for scaling rate evaluation • Have circulated EDTA in chip feed system to enable operation until a scheduled outage • Increase in Buckman anti-scale product dosage from 1.0 to 1.5 pounds per ton has been effective e ect e ttreatment eat e t
Scaling, g, continued •
Installed high pressure feeder with Andritz UniGrid™ during May outage Grid
•
Incremental specialty chemical cost about the same as kiln energy savings
•
Operated at 20% y substitution for a 10-day period prior to May outage
•
Significantly increased scale noticed on impregnation vessel during May outage inspection
•
Currently, C tl h have h handle dl on controling scale
Okay, off to the lab!
http://psychologytoday.com/blog/lifestyle-design/201003-science-homeschoolcultrure
EXPERIMENTAL PROCEDURES Experimental procedure: WL /GL-MCC pulping divided into four steps: Impregnation Stage (1) White liquor charge is 60% of the total EA-16.5% or 18.9%EA Liquor to Wood ratio - 3.5:1 Max.temperature-265 0F (130 0C) Time to hold at this temp-30 min Co-Current Stage (2) White liquor charge is 20% of the total EA-16.5% Liquor to Wood ratio - 4:1 Max.temperature-335 0F (168 0C) Time to temperature (130 to 168 0C)-20 min Time to hold at this temp-50 min
EXPERIMENTAL PROCEDURES, continued ti d Extraction Stage-1 (3) White Liquor charge is 10% of the total EA-16.5% or 18.9%EA Withdraw 1000ml of BL and add 10% WL makeup with weak BL to 1000ml Temperature drops to ~140C Time to raise the temp to -335F (168C)-15 min Time to hold at this temp-105 min Extraction Stage-2 (4) White Liquor charge is 10% of the total EA-16.5% or 18.9%EA Withdraw 1000ml of Black Liquor q and add 10% WL makeup p with weak BL to 1000ml Temperature drops to ~140 0C Time to raise the temp to 335F (168C)-15 min Time to hold at this temp-105 min
Three (3) Key Lab Results MCC PULPING RESULTS FIRST : By reducing the %EA (WL) and increasing GL to maintain total TTA, the lignin content goes up significantly and so do the rejects. In the substitution case, the EA from the WL is CRITICAL for maintaining acceptable kappa and rejects levels because of its delignification g capacity p y and p potentially yp penetration. The total TTA arising g from both WL & GL is not what controls these latter quantities SECOND : Hi h green liliquor charge High h addition dditi (40% GL, GL att 95% WL EA charge) h ) can llower th the kkappa number, but increase in rejects level cannot be avoided (FOR OVERSIZE CHIPS ONLY) THIRD : 1K 1.Keeping i Whit White liliquor charge h same as th thatt off b baseline li (16 (16.5%EA) 5%EA) and d adding ddi green liquor (5-20% of EA charge), lowers the kappa number as well as the rejects level (Accept chips 2-8 mm in thickness ONLY) 2.Keeping White liquor charge same as that of baseline (16.5% EA) and adding green liquor (5-20% of EA charge), lowers the kappa number, but not the rejects level. (Oversize chips>8 mm in thickness ONLY)
Result #1 • By reducing the %EA (WL) and increasing GL to maintain total TTA, the lignin content goes up significantly and so do the rejects (ACCEPT CHIPS DONE HERE) • In the substitution case, the EA from the WL is CRITICAL for maintaining acceptable kappa and rejects levels because of its delignification capacity and penetration (OVERSIZE CHIPS HERE) • The total TTA arising from both WL & GL is not what h t controls t l th these llatter tt quantities titi (OVERSIZE AGAIN)
Result #1,, continued MCC SW pulping (Accept chips)
Pulping process Baseline (Screened chips)
MCC pulping_16.5% EA-100%WL-Baseline
Screened Yield%
Kappa Number Rejects%
Reject kappa Number
44.1
25.3
0.7
65.0
45.3
33.9
1.0
72.3
45.1
40.4
1.5
-
46.1
45.4
1.7
81.2
45.3
33.9
1.0
-
44.4
28.2
0.8
-
43.3
24.4
0.6
69.6
SUBSTITUTION: I-A
I-B
I-C
MCC pulping-95%-WL-substituted GL5%16.5%EA-25%S-168C MCC p pulping-90%-WL-substituted p g GL10%16.5%EA-25%S-168C MCC pulping-85%-WL-substituted GL15%16.5%EA-25%S-168C
ADDITION: II-A (same as I-A)
II-B
II-C
MCC pulping-95%-WL-substituted GL5%16.5%EA-25%S-168C MCC pulping-95%WL-Added GL10%-16.5%EA25%S-168C MCC pulping-95%WL-Added GL15%-16.5%EA25%S-168C (5% WL is replaced by 15% GL)
Result #1, #1 continued •
In the addition case, it is evident that each 1% absolute increment from the baseline total TTA produces a decrement of about 4-5 kappa units and 0 2% absolute points rejects level decrease 0.2%
•
The screened yield does go down which is not surprising. At 10% GL substitution (19.7% total TTA), the overall kappa, rejects, and yield are roughly the same. same
•
The baseline kappa of 25.3 may theoretically be achieved at about 20.3% total TTA or 13.2% GL substitution ((each 1% of GL = 0.19% TTA))
•
Reject response follows a linear trend with the total TTA charge
Result #2 MCC-SW PULPING (Oversize chips) Pulping Process MCC pulping_16.5% pulping 16 5% EA_25S-168CEA 25S 168C (Screened chips) Baseline MCC pulping_16.5% EA_25%S-168COversize-Baseline
Screened Yield%
Kappa Number
Rejects%
Reject kappa Number
44.1
25.3
0.7
65.0
43.9
27.9
0.8
87.0
43.1
29.9
0.9
82.3
43.3
31.2
1.0
-
43.4
38.2
1.1
91.2
43.1
41.2
1.5
84.3
44.0
20.0
0.4
-
43.9
21.9
0.5
79.7
44.7
24.9
0.9
84.3
44.8
36.4
1.0
-
SUBSTITUTION ((OVERSIZE CHIPS): ) MCC pulping-95%WL-Sub GL5%16.5%EA-25%S-168C MCC pulping-90%WL-Sub GL10%16.5%EA-25%S-168C MCC pulping-85%WL-Sub GL15%16.5%EA-25%S-168C MCC pulping-80%-WL-substituted GL20%-16.5%EA-25%S-168C ADDITION (OVERSIZE CHIPS) CHIPS): MCC pulping-95%-WL-Added GL40%16.5%EA-25S-168C MCC pulping-90%-WL-Added GL40%16.5%EA-25S-168C 16.5%EA 25S 168C MCC pulping-85%-WL-Added GL40%16.5%EA-25S-168C MCC pulping-80%-WL-Added GL40%16.5%EA-25S-168C
Result #2, continued • High green liquor charge (40% GL) can lower the kappa number, but increase in rejects level cannot be avoided for oversize chips • Did nott find fi d the th kappa k numbers b equivalent i l t to t the th baseline pulp and higher rejects level in the GL substitution (Oversize chips>8 mm thickness) – 85% WL EA charge?
Result #3 PULPING OF ACCEPT AND OVERSIZE CHIPS WHILE MAINTAINING WL CHARGE SAME AS BASELINE =16.5% AND ADDING GL 5-15% IN THE COOKING LIQUOR – significant TTA increase Kappa Number
Pulping Process
MCC -17.4% EA-25%S95%WL-sub GL5%
MCC -18.4% EA-25%S90%WL-sub GL10%
MCC -19.4% EA-25%S85%WL-sub GL15%
MCC-16.5% EA-25%S100%WL-Baseline
Screen chips
Over size chips
Screened Yield
Reject kappa
Rejects
Screen
Over size
Screen
chips
chips
chips
Number
Over size chips
Screen chips
Over size chips
24 5 24.5
27 7 27.7
43 3 43.3
43 1 43.1
05 0.5
1 20 1.20
84 5 84.5
89 8 89.8
21.8
29.2
43.2
43.5
0.6
1.50
74.9
92.9
22.2
25.7
43.1
43.2
0.6
1.70
78.1
88.7
25.3
27.9
43.3
43.5
0.7
0.90
65.0
87.0
Result #3, continued MCC SW PULPING WITH ACCEPT AND OVERSIZE CHIPS KEEPING WL CHARGE 16.5% AND ADDING GL 5-15% IN THE COOKING LIQUOR
• Kappa appa number u be was as co comparable pa ab e to o base baseline e pulps while rejects level was higher when using oversize chips (In case of 19.4% EA-85%WL15%GL charge). • It shows that if we take the same white liquor charge (16.5%EA) ( % ) and keep on increasing the GL charge (TTA increase) there will be an increase in rejects level level, but declining kappa number.
INFLUENCE OF IMPREGNATION TIME ON ACCEPTED AND OVERSIZE SOFTWOOD CHIPS
Pretreatment time has an influence on the accept chips. The pretreatment profile effects the final kappa number (the more impregnation time, the lower the kappa number and rejects%) of the pulp
(Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into screened chips at 130C)
INFLUENCE OF IMPREGNATION TIME ON ACCEPT AND OVERSIZE CHIPS,, continued
Pretreatment time has influence on the MCC pulping on the oversize chips. The pretreatment profile effects the final kappa number (the more impregnation time, the lower the kappa number) of the pulp, but %rejects was not decreased!
(Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into oversize chips at 130C)
INFLUENCE OF IMPREGNATION TIME ON ACCEPT AND OVERSIZE SOFTWOOD CHIPS,, final
The accept chips (2-6 mm) were 100% impregnated, but the oversize chips were not 100% impregnated and have spots uncooked. Thus, rejects level is a real issue with oversize chips
Oversize chips
Accept chips
[Diffusion of sulfide (black, left chip in each frame) and hydroxide (red, right chip in each frame) into accept and oversize chips after pulping at 168C]
CONCLUSIONS • Energy benefits are clear • EA is very important • Penetration in cooking is KEY to success • Oversized chips pose an impediment to success; penetration must be dealt with in a logical manner • Scale can be managed
