irradiation of dissolving pulp by electron beams - Lenzing

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Economical considerations. . The price of irradiated of pulp is composed of high costs of botlh investment and Operation, the latter one mainly depending on expenses for electric power. From this Point of view, the irradiation of pulp would become an economically interesting innovation only if it is possible to carry out the viscose process with drastically reduced input chemicals (22% CS*, AR: 0.5) without any impairment of the fiber quality. Experimental For the experiments at lab plant and Pilot plant, 50 sheets (isostack) of Solucell 450 were irraldiated at STUDER AG with a 1OMeV Rhodotron TT300 accelerator built by IBA. The viscose quality was evaluated by PVC and KWP filter value (constant pressure) and particle i - I Irradiated Pulp fl2 kCy) BA: 10 MeV homogeneous nking of prllp chips Steeping lye concentratioe: 16% / Viscose of the sanuz composition was prepared for irradiated and -. LAB PLANT Viscose Quality Viscose Rheology I - -----.~-~~--~ _-_- - - ---~~_ 66 count. The viscose was also characterized by rheological investigations and analysis of byproducts, see Table 1 and Figure 1. No optimization of spinning conditions was done for these experiments. Table 1. Viscose composition for the experiments at lab plant and Pilot plant. Plant CS2 (%) AR Ce11 conc. Lab 36 0.6 Lab 32 0.6 Lab’ 28 0.55 Lab 26 0.5 Lab 22 0.5 Lab 28 0.55 Lab Pilot Figure 1. Experimental setup. -- 28 22 0.475 0.5 Standard Standard Standard Standard Standard Standard + 15.6% Standard + 15.6% Standard Con~entionai Ageiag Sieeping lye co~~~~~rati~a Standard -.--I--~ --.x .._““
Viscosity [ml/g] 290 1 without aftertreatment 260- Irrxhatwn Doiage: 12 kGy 250L 0 - I - I - I - . . 1 0 10 20 30 40 50 Sheet Numher Figure :t. Intrinsic viscosity distribution within one mini bale: homogeneity of irradiation at a dosage of 12 kGy. In case of irradiated pulp the hemicellulose concentration in press lye was higher than in the conventional process (2.25 g/l versus 1.48 g/l). 67 Ball J?zLZ of viscose. As published, the ball fall of viscose made from irradiated pulp should be lowel than that of viscose made from conventionally pre-aged pulp. Thus, it should be possible to increase the production capacity by using a higher content of irradiated cellulose under retention of the same ball fall of the viscose as before. However, only at high celluliose content (115.6% of Standard) and very low alkali content a lower ball fall seemed to result from the use of irradiated pulp (Figure 3). There is no benefit in ball fall by using irradiated Pulp= Polytlispersity of AC. No differente regarding polydispersity between aging and electron beam treatment could be observed in the respective viscosity range (Figure 4). 100% [ca 100% [CS 100% [ca 100% 100% 115.6% [CS2z 115.6% [cs2: 360/0; ARZ 0.q 32v4 AR: 0.6) 280/0; AR: o.5.q [oi2:26%, AR [cs2:22%, AR BS, AR 0.55j 28%, AR: O-Tl Wl 0.47Sj 2.6 Figure 3. Ball fall of various compositions of viscose prepared from irradiated and pre-aged pulp; lab-plant trials. Ball fall corrected to target cellulose concentration. 1.6 400 300 Intrinsic viscosity [mYg] Figure 4. Polydispersity vs. intrinsic viscosity of AC.
Page 1: 6.5 IRRADIATION OF DISSOLVING PULP
Page 5 and 6: In a wide range of CS2 input (36% t

irradiation of dissolving pulp by electron beams - Lenzing

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