文档介绍：列管式换热器设计说明书
设计者: 班级:
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指导教师设计成绩日期
目录
一、方案简介································································3
方案设计································································4
确定设计方案·····························································4
确定物性数据·····························································4
计算总传热系数···························································4
计算传热面积·····························································5
工艺结构尺寸·····························································5
换热器核算·······························································7
设计结果一览表··························································10
对设计的评述····························································11
附图(主体设备设计条件图)(详情参见图纸)·································
参考文献································································12
主要符号说明····························································12
附图··········································································
一、方案简介
本设计任务是利用冷流体(水)给硝基苯降温。利用热传递过程中对流传热原则,制成换热器,以供生产需要。下图(图1)是工业生产中用到的列管式换热器.
选择换热器时,要遵循经济,传热效果优,方便清洗,复合实际需要等原则。换热器分为几大类:夹套式换热器,沉浸式蛇管换热器,喷淋式换热器,套管式换热器,螺旋板式换热器,板翅式换热器,热管式换热器,列管式换热器等。不同的换热器适用于不同的场合。而列管式换热器在生产中被广泛利用。它的结构简单、坚固、制造较容易、处理能力大、适应性大、操作弹性较大。尤其在高压、高温和大型装置中使用更为普遍。所以首选列管式换热器作为设计基础。
二、方案设计
某厂在生产过程中,需将硝基苯液体从93℃冷却到50℃。处理能力为1×105吨/年。冷却介质采用自来水,入口温度27℃,出口温度37℃。要求换热器的管程和壳程的压降不大于10kPa。试设计能完成上述任务的列管式换热器。(每年按300天,每天24小时连续运行)
出口水温是可以自行改动的。冷却水温差最好在5~10℃
一年的工作日一般300~340天。可以自行选定。
(1)选择换热器的类型
两流体温度变化情况:
热流体进口温度93℃,出口温度50℃冷流体。
冷流体进口温度27℃,出口温度37℃。
流程安排说理要充分。
从两流体温度来看,估计换热器的管壁温度和壳体壁温之差不会很大,因此初步确定选用固定管板式换热器。
(2)流动空间及流速的确定
管内流体流态最好完全湍流。Re>10000,d=,μ=,ρ=1000,故ui≥
由于硝基苯的粘度比水的大,因此冷却水走管程,硝基苯走壳程。另外,这样的选择可以使硝基苯通过壳体壁面向空气中散热,提高冷却效果。同时,在此选择逆流。选用ф25×,管内流速取ui=。
2、确定物性数据
定性温度:可取流体进口温度的平均值。
壳程硝基苯的定性温度为:
管程流体的定性温度为:
根据定性温度,分别查取壳程和管程流体的有关物性数据。
℃下的有关物性数据如下:
密度ρo=1154 kg/m3
定压比热容 cpo=/(kg·℃)
导热系数λo=×30.