Design And Implementation Of Oil-Sewage Disposal Automation System Based On PLC

The sewage of oilfield contains large quantity of oily dirty mire and sulfide. Its direct drainage would result in serious pollution. This thesis aimes at the process flow of oil-field sewage treatment and develops a whole-course automatic monitoring system of oily sewage treatment.The main contents can be summarized as follows: the overall architecture design of the system, the design of the PLC controller and variable frequency controller, the hardware implementation and the software implementation for both upper-end and lower-end computers. According to the main trend of oilfield sewage treatment process control system at home and abroad, I analyze the operation principle diagrams and performance indexes, inquire the users more deeply about their requests in the given industrial environment. After analyzing the control tasks, I decided on the system architecture which uses the SIEMENS S7-300 series PLC as the core controller, and also choosed the corresponding instrumentation types. In order to meet the control function requirements, I crystallized the controller design which combines the traditional self-tuning PID algorithm and fuzzy self-tuning PID algorithm to achieve reliable, stable and real-time control effect for automatic variable frequency chemical feed and pH values. Then, the thesis illustrates the software development of the system from two aspects: the kernel modules for lower-end computer consisted of Chemical-feed automation and Mud-removing automation. I adopted the SIMATIC Step 7 development platform to do underlying PLC application development, and for Human-machine Interface of upper-end computer, I choosed the powerful FameView component software, implement the functions of colorful screen picture, automatic displaying and button-based operations. At last, the thesis provides an overview of the operation conditions of the system, and elaborates to some extent the subsequent development, the expansion of the system and some advanced intelligent control algorithms which have not been used yet.The purpose of this thesis is to implement a whole-course automatic monitoring system of oily sewage treatment, which is practical, powerful and reliable.