the vessel 16 such as with steam 18 injected to the vessel to a temperature in a range of 330 degrees deg fahrenheit f to 380 deg f or in a range 360 deg f to 370 f the chips are retained in the vessel for a period such as two 2 to fifteen 15 minutes or 4 to 10 minutes the chips are mechanically fiberized in a chip fiberizing vessel 17 such as defiberator or refiner vessel to a shines content of for example 10 to 50 or 30 to 45 the fiberized chips are discharged from the fiberizing vessel 17 and directed to one or more stages 22 of delignification such as a continuous or batch chemical reactor s 24 the delignification stages may remove or oxidize the lignin in the fiberized chips using oxidizing agents 26 such as one or more of oxygen hydrogen peroxide and ozone the fiberized chips from the vessel 17 may be optionally washed 25 using a wash liquid e g water before entering the delignification stage s 22 and washed between each of the individual delignification stages 24 fig1 shows by the branch u201c or u201d in the flow path that the washing or pressing stages 25 are optional and may precede the delignification stage s 22 and be between the individual delignification stages 24 in particular fig1 shows alternative flow paths branching at the u201c or u201d the delignification stages 22 may be the same in both braches of the flow path in particular each of the delignification stages 22 may add one or more of oxygen.