阅读说明：本技术 一种基于双向耦合的氯乙烯汽提优化方法 (Vinyl chloride stripping optimization method based on bidirectional coupling ) 是由 于现军 吕伟军 陆晟波 田朗 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种基于双向耦合的氯乙烯汽提优化方法,涉及聚氯乙烯生产控制领域。首先根据聚氯乙烯聚合段各聚合釜状态、聚合剩余时间、混料槽当前液位生成聚氯乙烯聚合负荷模型,其次根据聚氯乙烯干燥段进料流量生成聚氯乙烯干燥负荷模型。再次基础上使用氯乙烯汽提负荷控制器,通过双向耦合对汽提负荷进行补偿修正。最后引入汽提塔智能控制器,对汽提塔的塔顶温度和压力进行随动控制,实现在自动调节氯乙烯汽提负荷的基础上,确保控制精度与速率。(The invention discloses a vinyl chloride stripping optimization method based on bidirectional coupling, and relates to the field of polyvinyl chloride production control. Firstly, generating a polyvinyl chloride polymerization load model according to the states of all polymerization kettles at a polyvinyl chloride polymerization section, the polymerization residual time and the current liquid level of a mixing tank, and secondly, generating a polyvinyl chloride drying load model according to the feeding flow of a polyvinyl chloride drying section. And on the basis of the operation, a chloroethylene stripping load controller is used for compensating and correcting the stripping load through bidirectional coupling. And finally, introducing an intelligent controller of the stripping tower to perform follow-up control on the temperature and the pressure at the top of the stripping tower, so that the control precision and the control speed are ensured on the basis of automatically adjusting the stripping load of the chloroethylene.)

1. A vinyl chloride stripping optimization method based on bidirectional coupling comprises a polyvinyl chloride polymerization load calculation model, a polyvinyl chloride drying load calculation model, a vinyl chloride stripping load controller and a vinyl chloride stripping tower intelligent controller; the method is characterized in that: the method of bidirectional coupling of front and rear end loads is adopted, the change of the chloroethylene stripping load is quickly responded, the production device is stabilized, and the control precision of process parameters is improved, so that the aim of improving the product quality is fulfilled.

2. The model of claim 1, wherein the polyvinyl chloride production line comprises n polymerization reactors having Vf capacity, the base polymerization time (from the start of polymerization to the end of polymerization) is T, and the remaining polymerization time of each polymerization reactor is Ti, whereinThe total production capacity isProduction load。

3. The load on the polyvinyl chloride drying line of claim 1 is determined by the feed rate Qg.

4. The chloroethylene stripping load, the polyvinyl chloride polymerization load and the polyvinyl chloride drying load form a bidirectional coupling structure, the stripping load is compensated and controlled, and the load calculation formula is as follows:。

5. a vinyl chloride stripping duty controller as claimed in claim 1, outputting a stripping dutyThe rate of change thereof isFirst derivative ofThe feed-forward signal is respectively connected into the control loops of the temperature and the pressure at the top of the stripping tower, so that the corresponding controller can quickly respond to the change of the stripping load, and the control precision and the control speed are ensured on the basis of automatically adjusting the stripping load of the chloroethylene.

Technical Field

The invention relates to a vinyl chloride stripping optimization method based on bidirectional coupling, in particular to a control method for accurately adjusting a vinyl chloride stripping load according to a polyvinyl chloride polymerization load and a polyvinyl chloride drying load.

Background

The stripping of vinyl chloride is an intermediate link of the whole polyvinyl chloride production line, is an indispensable link for recovering vinyl chloride monomers in the production process of polyvinyl chloride and ensuring the quality of a final polyvinyl chloride product, and a stripping device is not only influenced by the polymerization production load of the front-end polyvinyl chloride in the production process, but also needs to pay attention to the drying condition of the rear-end polyvinyl chloride in real time, so that the stripping load is lifted to achieve the purpose of being matched with the front-end load and the rear-end load; in the stripping load lifting process, a feeding loop, a temperature loop, a pressure loop and a liquid level loop which need to be regulated have stronger coupling, so that the automatic lifting control of the chloroethylene stripping load has greater difficulty. The automatic adjustment of the chloroethylene stripping load can meet the requirement of automatic matching of front and rear end loads, and simultaneously can give consideration to the stability of the self state of the stripping device and improve the product quality.

In the prior chloroethylene stripping control process, due to uncertainty of load change of front and rear ends and strong coupling, the system is difficult to make corresponding timely and automatically adjusted to an optimal operation state, system fluctuation is easy to cause, and the product quality is reduced. Therefore, how to eliminate the influence of front and rear end load variation and improve the control precision and speed is a problem to be solved urgently in the control of the vinyl chloride stripping system.

Disclosure of Invention

In order to overcome the influence of front and rear end load change of the existing vinyl chloride stripping system, the invention provides a vinyl chloride stripping optimization method based on bidirectional coupling.

In order to achieve the purpose, the invention adopts the following technical scheme: a vinyl chloride stripping optimization method based on bidirectional coupling is disclosed, wherein the control method comprises a polyvinyl chloride polymerization load model, a polyvinyl chloride drying load model, a vinyl chloride stripping load controller and a stripping tower intelligent controller.

The polyvinyl chloride polymerization load model is characterized in that in the production process, the state of each polymerization kettle, the polymerization residual time and the current liquid level of the mixing tank are input into the polyvinyl chloride polymerization production load model, and the output of the polyvinyl chloride polymerization production load model adjusts the stripping load of the vinyl chloride.

The polyvinyl chloride drying load model is characterized in that in the production process, the polyvinyl chloride drying feeding flow is input into the polyvinyl chloride drying production load model, and the output of the polyvinyl chloride drying feeding flow is used for adjusting the stripping load of the polyvinyl chloride.

The chloroethylene stripping load controller is characterized in that a stripping load set value, a polyvinyl chloride drying load and a polyvinyl chloride polymerization load are input into the chloroethylene stripping load controller in the normal production process except for start and stop, and the output of the chloroethylene stripping load controller adjusts the intelligent controllers of the strippers.

The stripping tower intelligent controller comprises a stripping tower load set value, a current feeding flow, a top temperature set value, a current tower top temperature value, a top pressure set value, a current tower top pressure value and vinyl chloride stripping load controller output, wherein the stripping tower intelligent controller inputs the stripping tower load set value, the current feeding flow, the current tower top temperature set value, the current tower top pressure value and the vinyl chloride stripping load controller output, and the stripping tower intelligent controller outputs and controls the feeding amount, the.

Due to the adoption of the technical scheme, the invention has the following advantages: 1. the change of stripping load is quickly responded, the influence of stripping indexes is small, and the control precision is higher; 2. the front end load and the rear end load are coupled in two directions, so that the system is more stable.

Drawings

FIG. 1 is a control flow chart of the present invention.

Fig. 2 is a structural view of a vinyl chloride stripping duty controller.

Fig. 3 is a diagram of a stripping column intelligent controller.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1, a vinyl chloride stripping optimization method based on bidirectional coupling includes the following steps: (1) polyvinyl chloride polymerization load model calculation, (2) polyvinyl chloride drying load calculation, (3) vinyl chloride stripping load controller calculation, and (4) stripping tower intelligent controller.

The above (1) calculation of polyvinyl chloride polymerization load model, wherein the polyvinyl chloride production line has n V_fThe polymerization vessel having a capacity, wherein the reference time (time from the start of polymerization to the end of polymerization) of a single polymerization vessel is T, and the remaining polymerization time per polymerization vessel is T_iWhereinThe total production capacity isProduction load Q_jIs composed of。

The above (2) calculation of the polyvinyl chloride drying load model, wherein the load of the polyvinyl chloride drying production line depends on the feed flow Q_g。

As shown in fig. 2, the load controller performs compensation control on the stripping load, and the load calculation formula is as follows:。

the intelligent stripper controller (4) as shown in FIG. 3, based on the stripping load outputted from the stripping load controller for vinyl chlorideThe rate of change thereof isFirst derivative ofThe feed-forward signal is respectively connected into the control loops of the temperature and the pressure at the top of the stripping tower, so that the corresponding controller can quickly respond to the change of the stripping load, and the control precision and the control speed are ensured on the basis of automatically adjusting the stripping load of the chloroethylene.