精馏塔塔顶压力分程控制的设计论文.doc

摘要 本毕业设计主要是针对精馏塔塔顶压力的控制以及对精馏塔塔顶压力控制系统的研究设计。精馏塔塔顶压力控制系统主要是分程控制系统，当用户需要的控制精馏塔塔顶的压力时，避免因压力不稳定而导致影响产品的经济和质量。当塔顶压力过大时，加大液相向冷凝塔的流量，如果阀门全开压力仍旧增大时，则打开B 阀使多余的不凝气体排出，从而降低了塔顶的压力，保障了产品的质量和经济性。此次用的是热旁路与冷凝器的分程控制，分程控制系统是过程控制系统中复杂控制系统的一种，其主要特点是一个系统有多个阀门，从而要求一个控制器的输出要分成多段去控制不同的阀门。本设计中是一个系统控制两个阀门，当精馏塔塔顶压力小时，由一个阀门控制精馏塔塔顶压力，另一个阀门全关；当精馏塔塔顶压力在过大时，一个阀门全开，由另一个阀门控制精馏塔塔顶压力当因汽相旁路管线没有冷凝器，温度较主管线高，所以称之谓热旁路。为了防止精馏塔塔顶压力的不稳定，故采用热旁路分程控制法。因此关键在于选择控制阀的气开气关的类型和范围。 关键词：精馏塔，分程控制，压力，控制器，控制阀 Abstract The graduation design is mainly aimed at the top of the column pressure control and the top of the column pressure control system design. Top of the column pressure control system is mainly points process control system, when the user needs to control the pressure of the top of the column, avoid the pressure is not stable and lead to affect the products economy and quality. When the column top pressure too big when, to increase the flow of liquid cooling tower, if the valve is fully open pressure still increases, then open valve B excessive of discharge of the gas, so as to reduce the pressure of the top, guarantee the quality of the products and economy. The use is hot bypass and condenser process control points, points process control system is the process control system of a kind of complex control system, its main characteristic is a system with multiple valve and require a controller to the output of the divided into section to control different valve. This design is one system to control two valve, pressure in the top of the column when low, from one valve control tower of the column pressure, another valve seated; When the column pressure in the top high, one fully open valve, the valve control tower another column pressure when because of vapor phase bypass line no condenser, high temperature is competent line, so that the hot bypass . In order to prevent the top of the column of pressure is not stable, so the thermal bypass points SPC control. So the key is to choose the shut gas control valve type