A moisture control method for tobacco redrying machine based on predictive pi algorithm control system

Abstract

The invention discloses a tobacco redryer moisture control method based on a forecast Product Improve (PI) algorithm control system. The forecast PI algorithm control system achieves the method through a forecast PI controller. The tobacco redryer moisture control method includes the following steps: the initial opening value of an inlet humidification steam valve of an ordering machine is set according to experience, and the forecast PI algorithm control system adjusts the opening degree of the inlet steam valve and an outlet steam valve according to moisture and the opening limit value of an outlet of the ordering machine; feeding flow signals are collected, and the forecast PI algorithm control system adjusts the humidification amount of a mixed nozzle according to the feeding flow signals; and the tobacco control temperature and the hot air control temperature are preset in the forecast PI algorithm control system, the hot air temperature output by a heat exchanger and the tobacco temperature at the outlet position of the ordering machine are collected and fed back to the forecast PI algorithm control system, and then the forecast PI algorithm control system controls the temperature of the barrel wall of an ordering barrel. The tobacco redryer moisture control method achieves automatic control on moisture and temperature of a whole tobacco redrying line, improves field process control capability, and integrally improves tobacco redrying processing quality.

Description

technical field [0001] The invention relates to the technical field of threshing and redrying, in particular to a moisture control method for a tobacco leaf redrying machine based on a predictive PI algorithm control system. Background technique [0002] Tobacco redrying process is a multi-interference, strong coupling, large lag, nonlinear, uncertain process with large heat capacity. In the production process, there is always a heat exchange effect between the heat transfer medium (hot gas) with a certain temperature, humidity, pressure, and flow rate and the tobacco leaves in the process of relative motion, so as to achieve the purposes of drying, cooling, and moisture resurgence of the tobacco leaves. Changes in temperature and humidity in any section of different processes will affect the changes in the parameters of each section and the moisture content of the exported tobacco leaves, which makes the establishment of the system's mechanism model quite complicated, as sh...

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Problems solved by technology

[0003] 1) There are many interference factors: the moisture, temperature, place of origin, variety, and grade of the imported tobacco leaves have a very important impact on the outlet moisture; the pressure, temperature and saturation degree of the heating steam and rehumidified steam directly affect the moisture and temperature of the exported tobacco leaves; the environment The temperature and humidity of the air also have a great indirect effect on the moisture and temperature of the tobacco leaves in the cooling stage

[0004] 2) There are certain problems in the measuring instrument, especially the accuracy of the infrared moisture meter is greatly affected by the outside world, and the reference value is prone to drift. The measured value of the cold room moisture meter is polluted by electrical noise, and the measured value fluctuates frequently, which seriously affects the closed-loop control. performance

[0005] 3) The characteristics of the production process are changeable: affected by the front leaf threshing process, the feed flow rate of tobacco leaves and the speed of the tobacco leaf feeder sometimes need to be adjusted to meet the continuous production, which leads to changes in the characteristic parameters of the process; at the same time , Tobacco rebaking works in high temperature, high humidity and dusty environment, and the equipment will also experience abnormalities. In this case, the operator needs to change the process operation at any time, so that the process characteristics are diverse, and it is difficult to achieve stable PID closed-loop control

[0006] 4) Moisture control is a large lagging process: often after the outlet moisture changes, it is not timely to control it, and the direct consequence is that the moisture fluctuates up and down the set value and cannot be stabilized

However, in the field production process, it is often affected by various factors (such as steam pressure, setting value changes, tobacco leaf flow moisture, etc.), and the control will become much more complicated.

Moreover, in the entire roasting machine control system, there are as many as ten (or even more) loops that need to be controlled, and they still rely on manual experience to control. The difficulty is conceivable, and the accuracy cannot be guaranteed.

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