基于科氏质量流量计的聚氨酯计量控制系统设计

Design of Polyurethane Metering Control System Based on Coriolis Mass Flowmeter

作为一种重要的聚氨酯树脂合成原料,二苯基甲烷二异氰酸酯(MDI)价格昂贵且对产品性能影响显著,需要精确计量。在聚氨酯树脂规模化生产过程中,需要多次使用MDI。原计量系统采用一个科氏质量流量计(CMF),分别计量多个管道的MDI质量。为避免管道中由于MDI残留造成计量误差,在原计量系统的基础上,增加了多个CMF,并采用可编程逻辑控制器(PLC)控制。介绍了计量系统的结构和工作原理,给出了计量系统的控制流程。对比了改造前后的计量系统结构组成和特点,阐述了流量计的结构、原理和选型,比较了几种CMF算法的优劣性。基于CMF的聚氨酯计量控制系统在试生产中达到预期要求,提高了计量系统的测量精度。

As an important raw material for synthesis of polyurethane resin,diphenyl-methane-diisocyanate（ MDI） needs to be precisely weighed because it is expensive and has a significant impact on product performance. In the process of large scale production of the polyurethane,it is necessary to use MDI multiple times. In original metering system,Coriolis mass flowmeter（ CMF） is used to respectively measure the mass of MDI in multiple pipelines. In order to avoid the measurement error caused by the residual MDI in the pipeline,a number of CMFs are added based on the original measurement system and PLC control is adopted. The structure and operation principle of the metering system are introduced,the control flowchart of the metering system is given. The composition and structural characteristics of the metering system before and after revision are compared,and the structure,principle and model selection of the flowmeters are described,the advantages and disadvantages of several algorithms of CMF are compared. The polyurethane metering control system based on CMF achieves expected results in trial production and improves the measurement accuracy of the metering system.