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Licensed Unlicensed Requires Authentication Published by De Gruyter May 23, 2018

TMP properties and refining conditions in a CD82 chip refiner. Part I: Step changes of process variables, description of the tests

Rita Ferritsius, Olof Ferritsius, Jan Hill, Anders Karlström and Karin Eriksson

Abstract

The study explores how changes in process variables, residence time and pulp consistency in refining influence the pulp properties. The equipment utilized in this study was a conical disc chip refiner (RGP82CD) producing thermomechanical pulp (TMP). The focus was on the ratio between tensile index and specific energy consumption. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. This showed that the CD-refiner, with the flat and conical refining zone, has a process performance similar to that of a two-stage refiner set-up, and that the consistency in both refining zones is of high importance. Comparing different periods revealed that even if the values of measured blow line consistency are similar, significant differences in the estimated consistency in the flat zone can prevail. Therefore, only monitoring blow line consistency is not enough. Specifically, it was found that the pulp consistency after the flat zone could be very high, considerably higher than in the blow line, and this could have negative effects on tensile index and fibre length.

Funding statement: This publication is a part of the Energy Efficient Mechanical Pulping (e2mp) program at Mid Sweden University funded by the Knowledge Foundation, Stora Enso, SCA, Holmen, and Valmet. Special thanks to all who gave support to these trials and testing of the pulps.

  1. Conflict of interest: The authors do not have any conflicts of interest to declare.

Appendix

Table 4

Data from TEST2.

Composite Pulp Sample212223242526272829
Load, MW23.724.624.923.321.923.124.224.221.4
Gap FZ, mm1.351.201.051.211.371.351.361.351.36
Gap CD, mm0.780.790.780.770.770.790.780.750.78
Dil. water FZ, l/s3.423.433.433.433.433.363.263.173.43
Dil. water CD, l/s5.235.245.245.235.235.235.235.245.23
Prod., admt/h15.915.915.915.915.915.915.915.915.9
SE., kWh/admt149315521569147313811457152515271353
Calc. conc. FZ, %76.784.389.877.969.375.981.082.068.2
Calc. conc. CD, %60.064.165.458.953.758.664.065.352.3
Tot. res. time, s1.231.281.301.231.171.221.281.301.15
Res. time ratio FZ/CD1.030.980.971.041.111.051.000.991.13
Force FZ 3, N1.111.201.261.191.211.151.111.131.26
Pulp conc., %57.661.062.657.053.558.962.564.253.8
Freeness, ml CSF198192182197225202192193230
Fiber length (ww), mm2.111.961.922.152.292.202.032.012.31
CWT, μm7.88.07.87.97.88.07.97.98.0
Fibrillation, %5.435.645.625.395.565.826.065.675.62
Curl, %14.113.613.513.613.613.913.813.413.6
Somerville, %1.611.151.041.461.781.441.321.341.79
Density, kg/m3329352362343330343348358326
Tensile index, Nm/g27.727.228.030.129.729.627.327.129.1
Elongation, %1.781.711.731.821.731.791.781.731.83
Tear index, mNm2/g6.375.725.866.727.216.885.956.117.27
Light scatt. coeff. m2/kg45.347.748.145.943.245.547.047.843.5

Table 5

Data from TEST3.

Composite Pulp Sample31323334
Load, MW22.422.122.121.9
Gap FZ, mm1.231.241.221.23
Gap CD, mm0.630.570.630.64
Dil. water FZ, l/s3.783.793.783.79
Dil. water CD, l/s5.125.115.125.06
Prod., admt/h15.015.015.015.0
SE., kWh/admt1496147614701463
Calc. conc. FZ, %60.758.059.859.5
Calc. conc. CD, %50.649.649.449.5
Tot. res. time, s1.031.151.151.15
Res. time ratio FZ/CD1.130.990.990.99
Force FZ 3, N1.231.281.271.25
Pulp conc., %51.451.450.850.8
Freeness, ml CSF214212213220
Fiber length (ww), mm2.222.212.282.20
CWT, μm7.97.97.87.9
Fibrillation, %5.485.315.725.72
Curl, %14.513.714.814.0
Somerville, %1.781.881.751.86
Density, kg/m3316328337340
Tensile index, Nm/g26.826.327.827.9
Elongation, %1.781.711.771.78
Tear index, mNm2/g6.426.366.826.79
Light scatt. coeff. m2/kg44.044.243.843.9

Table 6

Data from TEST4.

Composite Pulp Sample353637383940414243444546474849
Load, MW19.719.619.719.519.621.521.521.621.321.322.522.522.322.422.5
Gap FZ, mm1.481.481.481.491.481.481.471.471.481.481.491.481.481.481.48
Gap CD, mm1.141.141.131.131.141.151.151.151.151.141.111.121.141.141.13
Dil. water FZ, l/s3.393.393.393.393.403.413.403.403.393.393.383.413.403.433.38
Dil. water CD, l/s3.893.883.883.883.883.883.883.883.883.893.883.893.883.893.88
Prod., admt/h12.512.512.512.512.514.414.414.414.414.415.915.915.915.915.9
SE., kWh/admt158015661578156415681490149414971478148214181415140314101418
Calc. conc. FZ, %75.575.075.074.174.276.076.476.575.275.676.676.275.875.677.6
Calc. conc. CD, %58.658.657.657.764.564.965.263.964.265.965.465.065.366.1
Tot. res. time, s1.591.581.581.571.571.471.481.481.461.471.361.351.351.351.36
Res. time ratio FZ/CD0.850.850.850.860.860.800.800.800.810.810.800.800.800.800.80
Force FZ 3, N0.560.550.560.580.580.790.780.800.780.790.991.021.000.990.99
Pulp conc., %56.763.260.358.958.867.768.570.464.065.870.873.270.969.575.8
Freeness, ml CSF183198190191194235235260226253303327295280307
Fiber length (ww), mm2.342.332.322.332.322.312.312.282.302.312.332.342.342.362.28
CWT, μm7.67.77.87.77.77.97.98.07.97.98.18.28.08.08.3
Fibrillation, %6.76.476.426.386.66.136.246.186.096.196.156.126.286.155.97
Curl, %15.315.115.114.915.414.414.614.514.614.614.614.615.014.814.2
Somerville, %0.880.920.850.780.951.261.271.221.321.281.401.541.431.391.34
Density, kg/m3362355360360364341352350356346336337339350339
Tensile index, Nm/g34.431.633.132.932.928.128.628.030.528.425.524.527.228.124.9
Elongation, %1.921.831.861.911.881.751.661.671.711.691.531.561.631.681.56
Tear index, mNm2/g7.477.227.597.317.377.166.956.486.936.616.196.236.556.836.06
Light scatt. coeff. m2/kg47.547.447.347.147.346.047.147.447.346.445.244.645.245.444.9

Table 7

Data from TEST5.

Composite Pulp Sample505152535455565758596061626364
Load, MW21.922.322.122.122.618.418.118.518.918.720.019.018.817.617.4
Gap FZ, mm0.870.870.860.860.870.850.850.860.860.860.850.860.850.850.86
Gap CD, mm0.670.670.670.670.650.650.640.650.650.650.670.660.660.650.65
Dil. water FZ, l/s3.293.283.283.283.283.513.513.513.513.513.513.513.513.513.52
Dil. water CD, l/s4.694.704.704.694.704.694.694.694.694.694.454.444.454.444.44
Prod., admt/h14.214.214.214.214.214.314.314.314.314.314.214.214.214.214.2
SE., kWh/admt154015681555155515881285126412971321130614071339132212431223
Calc. conc. FZ, %61.262.562.162.262.553.452.953.654.353.956.454.654.252.451.9
Calc. conc. CD, %57.759.258.458.560.445.444.745.746.846.251.548.848.145.244.5
Tot. res. time, s1.161.171.171.171.181.041.031.041.051.051.101.071.061.041.03
Res. time ratio FZ/CD0.940.920.930.930.901.111.131.111.091.101.011.051.061.111.12
Force FZ 3, N1.561.641.621.631.681.281.271.301.321.311.421.291.301.251.26
Pulp conc., %59.061.259.660.761.445.043.745.548.048.649.049.748.744.344.4
Freeness, ml CSF190194194203205262270259252253214235244286295
Fiber length (ww), mm2.292.242.222.242.192.332.392.392.342.372.342.382.352.332.38
CWT, μm7.87.87.97.88.07.87.87.87.87.97.97.87.77.67.7
Fibrillation, %6.36.36.46.296.25.926.036.056.036.126.166.056.045.916.12
Curl, %14.714.514.514.914.413.714.013.614.013.914.213.914.113.813.9
Somerville, %0.860.760.750.800.641.752.001.661.751.721.321.421.752.242.28
Density, kg/m3372375376381373333329340340338348333329331327
Tensile index, Nm/g34.233.833.933.532.127.926.828.529.128.831.229.027.226.025.8
Elongation, %1.801.831.811.911.821.761.711.761.811.761.851.781.781.681.75
Tear index, mNm2/g7.447.517.747.547.127.186.887.167.147.107.357.266.926.756.44
Light scatt. coeff. m2/kg46.647.247.146.547.143.243.042.843.443.544.543.543.142.041.9

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Received: 2016-08-03
Accepted: 2017-12-18
Published Online: 2018-05-23
Published in Print: 2018-05-23

© 2018 Walter de Gruyter GmbH, Berlin/Boston

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