Sulphuric acid was added to reach a target level of 0.75%
(db) based on dry wheat straw. Steam and water were used
to increase the moisture content and temperature. A short
conveyor belt was used for feeding and levelling the wheat
straw material flow. A mixer screw was connected to the conveyor
and the sulphuric acid solutionwas sprayed on the straw
material at the inlet of the mixer screw. Hot water and steam
were injected into the mixer screw to increase the temperature
of the straw material to a range of 70–90 ◦C. The moisture
content (MC) was increased and the pH of the straw mixture
was decreased to approximately 4–5. The production rate was
approximately 120 kg/h and the MC level was set to 100%. A
slightly higher MC level of the pretreated straw was obtained
(MC = 107%).