板式换热器在酸洗净化中的工业应用研究

Research on Industrial Application of Plate Heat Exchangers to Acid Scrubbing Process

南京化学工业(集团)公司研究院和山西省平定县磷肥厂共同开发用稀酸板式换热器间冷稀酸的酸洗净化流程,于1991年10月投入工业应用并进行了运行考核。使用代号为A的材料压制板片,换热器在正常工艺条件下的传热系数>3200W/(m^2·K),经1992年7～8月高温季节的生产运行考核表明,当板式换热器进水温度为30～31℃时,稀酸出口温度为35～37℃,相应洗涤塔炉气出口温度<40℃,能满足生产要求;传热系数与板片两侧介质流速间关系的经验式为K=6045W_b^(0.30)W_c^(0.25)(W_h为酸流速、W_c为水流速);流体阻力用△P=EupW^2表示,Eu=15953Re^(-0.487)(流道受压时)和Eu=2675Re^(-0.342)(流道受胀时);运行10个月后拆开检查,板片的酸侧无锈斑、无蚀痕、光亮如新,水侧有薄层水垢,密封圈无老化和溶胀。使用该换热器具有投资省、占地小、效率高、操作简便、技术可靠等优点。

A plate heat exchanger was developed for indirect cooling of weak acid from the roaster gas scrubbing tower in H2SO4 plants. It was constructed of pressed plates of material A and had a heat transfer coefficient of>3200W/(m2·K) under the normal process conditions. The industrial test during July and August (the hottest season in China) showed that the plate heat exchanger functioned satisfactorily and when the inlet temperature of cooling water was 30~31℃. weak acid temperature was reduced to 35 ~ 37℃, the corresponding temperature of roaster gas from scrubbing tower being<40℃. An empiric formula for correlation of the heat transfer coefficient with fluid velocities on both sides of plate is given : K = 6045Wh0.30We0.25, where Wh is for acid velocity and We for water. The pressure drop is represented as ΔP = Eupw2, where Eu = 15953Re-0.487(for the fluid passage pressed) or Eu = 26r5Re-0.342 (for the fluid passage expanded). The haet exchanger was examined after 10 months of operation. No corrosion was detected and the plates preserved metallic lustre on acid pass and a thin layer of scale was found on water pass. Ageing and swelling of the gaskete didn't occured. The heat exchanger needs lower cost and less space, but supplies high efficiency, easy operation and reliable performance.