球罐焊后热处理温度自动控制系统的研究

发布时间：2018-03-15 03:11

本文选题：球罐焊后热处理　切入点：残余应力　出处：《中国计量学院》2016年硕士论文　论文类型：学位论文

【摘要】：球罐广泛应用于石化、能源等行业,常用来储存易燃易爆等危险的化学品。球罐在使用的过程中焊缝部位往往容易产生裂纹,究其原因是球壳板焊缝存在较大的焊接残余应力,球罐焊后进行热处理是消除残余应力的重要工序。通常根据球壳外表面测得的温度,凭人工经验调节喷油嘴来控制热处理的加热速度和温度。但是随着球罐的进一步大型化,需要采集的温度点有几十个甚至上百个,传统的热处理温度控制方式很难按照国标要求的热处理工艺进行。研究出合适的球罐焊后热处理温度控制系统成为目前业内遇到的一大难题。本文针对目前国内应用最广泛的球罐焊后热处理方式进行研究,针对热处理温度具有纯滞后、非线性的特点,将智能控制领域应用比较成熟的BP神经网络PID算法引入到球罐焊后热处理温度控制的课题中。本文的工作和创新点如下。(1)研究GB12337-2014对球罐焊后热处理温度控制的技术要求,使用BP神经网络PID和常规PID两种控制算法对球罐热处理时阀门响应进行仿真对比,并使用BP-NN-PID对现场球罐热处理工艺曲线进行仿真跟踪,验证了前者对阀门响应比后者响应速度快,仿真结果表明BP-NN-PID控制算法可以对球罐焊后热处理温度进行控制。(2)设计小型球罐,内径为2.8m,壁厚24mm,4支柱形式,球壳结构形式采用橘瓣式三带球罐。搭建该小型球罐现场热处理实验装置,包括测温仪器的型号及安装、保温层的厚度及铺设步骤,钢带的制作形式等。对该小型球罐进行热工计算,得出热处理每个阶段的燃烧速率和周期燃油量,为热处理温度控制提供参考。使用Fluent软件对球罐热处理内部流场和温度场进行仿真研究。(3)在仿真分析的基础上对球罐焊后热处理温度自动控制系统进行软件设计。利用西门子自动化软件对温度自动控制系统进行上位机和下位机的程序编写。在山东某热处理公司对2.8m实验球罐进行焊后热处理,分别选择常规PID控制方式和BP神经网络PID控制方式进行控制,实验结果表明后者控制的温度曲线更符合GB12337-2014中的要求,效果较好。为下一步国内球罐焊后热处理实现温度自动控制奠定了基础。
[Abstract]:Spherical tanks are widely used in petrochemical, energy and other industries, and are often used to store dangerous chemicals, such as flammable and explosive chemicals. The heat treatment of spherical tank after welding is an important procedure to eliminate residual stress. Usually according to the temperature measured on the outer surface of the spherical shell, the heating speed and temperature of heat treatment are controlled by adjusting the nozzle manually. However, as the spherical tank becomes larger, There are dozens or even hundreds of temperature points that need to be collected. The traditional heat treatment temperature control method is difficult to carry out according to the heat treatment process required by the national standard. It has become a big problem in the industry to develop a suitable temperature control system for the post-welding heat treatment of spherical tank. The most widely used post-weld heat treatment method for spherical tank was studied. The heat treatment temperature has the characteristics of pure hysteresis and nonlinearity. The BP neural network (PID) algorithm, which is mature in the field of intelligent control, is introduced into the control of post-weld heat treatment temperature of spherical tank. The work and innovation of this paper are as follows: 1) the technical requirements of GB12337-2014 for post-weld heat treatment temperature control of spherical tank are studied. Two control algorithms, BP neural network PID and conventional PID, are used to simulate and compare the valve response of spherical tank during heat treatment, and BP-NN-PID is used to track the heat treatment process curve of spherical tank. The results of simulation show that the BP-NN-PID control algorithm can control the post-weld heat treatment temperature of spherical tank. The design of small spherical tank with inner diameter of 2.8 m and wall thickness of 24 mm and 4 strut is verified. The spherical shell structure adopts the orange flap type three-belt ball tank. The field heat treatment experimental device of the small spherical tank is built, including the type and installation of the temperature measuring instrument, the thickness of the insulation layer and the laying steps. The thermal calculation of the small spherical tank is carried out, and the combustion rate and periodic fuel quantity in each stage of heat treatment are obtained. Fluent software is used to simulate the flow field and temperature field of spherical tank heat treatment. On the basis of simulation and analysis, the software design of automatic control system for heat treatment temperature after welding of spherical tank is carried out. The program of upper computer and lower computer for temperature automatic control system is programmed by Siemens automatic software. The 2.8m experimental spherical tank is treated after welding in a heat treatment company in Shandong Province. The conventional PID control mode and BP neural network PID control mode are selected respectively. The experimental results show that the temperature curve of the latter control is more in line with the requirements of GB12337-2014. It lays a foundation for the realization of automatic temperature control after welding heat treatment of spherical tank in our country.
【学位授予单位】：中国计量学院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP273

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