Specific Energy Consumption Regression and Process Parameters Optimization in Wet-Briquetting of Rice Straw at Normal Temperature

Abstract

In the normal-temperature (20 to 25 °C) wet briquetting of straw, the lignin becomes softened and briquetted by means of friction heat from the briquetting at some compressing force and moisture ratio. With an electronic universal testing machine and a self-developed normal- temperature wet briquetting device, tests were carried out for normal-temperature wet briquetting of rice straws with different compressing rate, material moisture, die length-diameter ratio, and die opening taper, using a quadratic regression-orthogonal design. Based on the characteristic curves of normal-temperature wet briquetting, the specific energy consumption was calculated by stepped regression and then integration for summation. Thereby, a specific energy consumption model was established. Next, an interactive analysis was made between single-factor and two-factor designs. Optimal combination of factors, i.e. 17.3% moisture, 44.5 mm/min compressing rate, 45° die opening taper, and 5.3 die length-diameter ratio, were obtained while the specific energy consumption was minimized. Further, the work provided references for process parameters design of the normal-temperature wet briquetting device for straw.