摘要
Aqueous ammonia mixed with caustic potash as wheat straw pulping liquor was investigated. The caustic potash not only roduced the NH3 usage and cooking time, but also provided a potassium source as a fertilizer in the black liquor. Excessive NH3 in black liquor from wheat straw NF4OH-KOH pulping process was recovered by batch distillation with a 98% recovery rate of free NH3 under atmospheric pressure and constant reflux. The temperature at the bottom of the column was controlled at 104 - 105 ℃. After removal of free NH3, the black liquor contained 8.4 g/L NH3-N and 7. 04 g/L total potassium, with a substantial amount of ammoniacal lignin, and it could be used as a liquid fertilizer for farming. The height equivalent to a theoretical plate （HETP） of a rectifier for recovering free NH3 was calculated. The diameter and height of packing of the rectifier based on a daily consumption of 75 t oven-dry wheat straw were estimated.
Aqueous ammonia mixed with caustic potash as wheat straw pulping liquor was investigated.The caustic potash not only reduced the NH3 usage and cooking time,but also provided a potassium source as a fertilizer in the black liquor.Excessive NH3 in black liquor from wheat straw NH4OH-KOH pulping process was recovered by batch distillation with a 98% recovery rate of free NH3 under atmospheric pressure and constant reflux.The temperature at the bottom of the column was controlled at 104-105℃.After removal of free NH3,the black liquor contained 8.4 g/L NH3-N and 7.04 g/L total potassium,with a substantial amount of ammoniacal lignin,and it could be used as a liquid fertilizer for farming.The height equivalent to a theoretical plate (HETP) of a rectifier for recovering free NH3 was calculated.The diameter and height of packing of the rectifier based on a daily consumption of 75 t oven-dry wheat straw were estimated.
基金
Natural Science Foundation of Jiangxi Province,China(No.2009GZH0004)
