【正文】 從尿素溶液中分離出來 ,然后又全部返回高壓合成塔 ,從而提高原料氨和二氧化碳的利用率的方法。 為此 ,合成塔排出液 (含有尿素 ,氨和二氧化碳的水溶液 )要先進行組分分離 ,使成為多少較 純凈的尿素水溶液和未反應(yīng)的 3NH 、 2CO 和 OH2 的混合物 。 尿素的生產(chǎn)工藝比較成熟 ,主要的生產(chǎn)方法有 :不循環(huán)法 ,部分循環(huán)法 ,水溶液全循環(huán)法 ,氣提法 等 。 尿素作為最重要的氮素化學(xué)肥料 ,在中國這樣一個農(nóng)業(yè)大國中 ,其發(fā)展是不言而喻的。 20xx年 ,全球尿素需求量約 噸 ,比 20xx年增長 ％ 。 由此看來 ,尿素產(chǎn)品涉及到國民經(jīng)濟和人民生活的各個領(lǐng)域 。 其是中性速效肥料 ,施于土壤中以后不殘留使土壤惡化的酸根 ,而且分解出來的二氧化碳也可以為植物吸收 。尿素還可作為多種用途的添加劑 ,用于醫(yī)藥和試劑生產(chǎn)中 。工 業(yè)尿素的總消耗量約一半是作為尿素甲醛樹脂和三聚氰胺。四川理工學(xué)院畢業(yè)設(shè)計 (論文 ) 目錄 I 目 錄 第一章 總 論 ................................................................................................................1 .......................................................................................................................1 .............................................................................................................1 .........................................................................................................2 ................................................................................................................2 ..................................................................................................2 .........................................................................................................3 .........................................................................................................3 ......................................................................................................3 ......................................................................................................4 ......................................................................................................4 .........................................................................................................4 第二章 物料衡算 ........................................................................................................5 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.............................................................................................................9 ........................................................................................9 .........................................................................................................9 ........................................................................... 10 第三章 熱量衡算 ...................................................................................................... 11 .................................................................................................................. 11 ....................................................................................................... 11 ....................................................................................................... 11 ....................................................................................................... 11 四川理工學(xué)院畢業(yè)設(shè)計 (論文 ) 目錄 II .................................................................................. 14 ........................................................................................................... 14 ....................................................................................................... 14 ....................................................................................................... 14 ........................................................................... 15 ........................................................................................................... 16 ....................................................................................................... 16 ....................................................................................................... 16 ........................................................................... 17 第四章 主要設(shè)備工藝設(shè)計 .................................................................................... 18 .................................................................................................................. 18 件 ....................................................................................................... 18 ......................................................................................... 18 ........................................................................................................... 18 ....................................................................................................... 18 A ..................................................................................................... 19 ........................................................................................................... 19 ....................................................................................................... 20 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