KRAFT PULP MILL SCALE CONTROL WITH END GROUP MODIFIED POLYCARBOXYLATES
Scale build-up on metal surfaces of a black liquor evaporator is prevented or mitigated by treating the black liquor with a deposit inhibiting concentration of a water-soluble polymer containing a polycarboxylate chain and a 3-mercaptopropionic acid end group.
1 . A method for inhibiting scale build-up on metal surfaces of a black liquor evaporator, the method comprising treating the black liquor with a deposit inhibiting concentration of a water-soluble polymer comprising a polycarboxylate chain and a 3-mercaptopropionic acid end group.
2 . The method according to claim 1 , wherein the water-soluble polymer has general structure R1-R2-R3, wherein R2 is a polycarboxylate, R1 and R3 are independently hydrogen or an end group, and at least one of R1 and R3 is the end group —S—CH 2 CH 2 COOH.
3 . The method according to claim 1 , wherein the water-soluble polymer comprises a homopolymer or copolymer of acrylic acid.
4 . The method according to claim 1 , wherein the concentration of the water-soluble polymer in the black liquor is 100 ppm or greater.
5 . The method according to claim 1 , wherein the water-soluble polymer has a weight average molecular weight of 2000 to 12000 daltons.
6 . The method according to claim 1 , wherein the water-soluble polymer is a homopolymer or copolymer of acrylic acid chain terminated with 3-mercaptopropionic acid.
7 . A composition comprising black liquor and 50 ppm or more of a water-soluble polymer comprising a polycarboxylate chain and a 3-mercaptopropionic acid end group.
8 . The composition according to claim 7 , wherein the black liquor has at least 50% solids by weight.
9 . The composition according to claim 7 , wherein the water-soluble polymer has general structure R1-R2-R3, wherein R2 is a polycarboxylate, R1 and R3 are independently hydrogen or an end group, and at least one of R1 and R3 is the end group —S—CH 2 CH 2 COOH.
10 . The composition according to claim 7 , wherein the water-soluble polymer comprises a homopolymer or copolymer of acrylic acid.
11 . The composition according to claim 7 , wherein the concentration of the water-soluble polymer is 100 ppm or greater.
12 . The composition according to claim 7 , wherein the water-soluble polymer has a weight average molecular weight of 2000 to 12000 daltons.
13 . The composition according to claim 7 , wherein the water-soluble polymer is a homopolymer or copolymer of acrylic acid chain terminated with 3-mercaptopropionic acid.
14 . A system for recovering waste material from a kraft pulp process for paper production comprising an evaporator for concentrating a weak black liquor to a heavy black liquor, wherein the evaporator comprises black liquor and a scale-inhibiting amount of a water-soluble polymer, wherein the water-soluble polymer comprises a polycarboxylate chain and a 3-mercaptopropionic acid end group.
15 . The system according to claim 14 , wherein the black liquor has at least 50% solids by weight.
16 . The system according to claim 14 , wherein the water-soluble polymer has general structure R1-R2-R3, wherein R2 is a polycarboxylate, R1 and R3 are independently hydrogen or an end group, and at least one of R1 and R3 is the end group —S—CH 2 CH 2 COOH.
17 . The system according to claim 14 , wherein the water-soluble polymer comprises a homopolymer or copolymer of acrylic acid.
18 . The system according to claim 14 , wherein the concentration of the water-soluble polymer is 100 ppm or greater.
19 . The system according to claim 14 , wherein the water-soluble polymer has a weight average molecular weight of 2000 to 12000 daltons.
20 . The system according to claim 17 , wherein the water-soluble polymer is a homopolymer or copolymer of acrylic acid chain terminated with 3-mercaptopropionic acid.