Moisture control method for airflow cut-tobacco drier

Abstract

The invention discloses a moisture control method for an airflow cut-tobacco drier and belongs to the technical field of tobacco preparation. A moisture meter is used for detecting moisture at an outlet, and a high-temperature humidity sensor is used for detecting the relative humidity of a process gas; when the airflow cut-tobacco drier is in the zero-load state, and the relative humidity of the process gas is smaller than or equal to 25 percent and larger than or equal to 20 percent, the original simulated water set value is maintained, and when the relative humidity of the process gas is smaller than 20 percent or larger than 25 percent, the simulated water set value is increased or reduced respectively; and when the airflow cut-tobacco drier is in the load state, the moisture at the outlet is compared with the set moisture value, the temperature of the process gas is compared with the set temperature value, and a PID (Proportion Integration Differentiation) controller adjusts and controls the water loading quantity according to the difference values of the two parts. As the humidity of the process gas is controlled in the zero-load stage, fluctuation of initial moisture is reduced; and as the influence factors of the temperature of the process gas is introduced in the load stage, the moisture at the outlet is stabilized, the equipment process control capability is enhanced and the tobacco shred processing quality is improved.

Description

technical field [0001] The invention relates to a moisture control method for an airflow type shred dryer, belonging to the technical field of tobacco preparation. Background technique [0002] In the tobacco shredded process, the air-flow shredded dryer is mainly used for rapid drying, expansion and shaping of high-temperature and high-humidity shredded tobacco, and the stability of the moisture in the shredded tobacco at the outlet plays a key role in the quality of the finished product in the flavoring process. Since the working medium of the air flow drying machine is high-temperature gas, the change of temperature and humidity and the hysteresis of control all have an adverse effect on the stability of the outlet moisture, resulting in large fluctuations in the outlet moisture. [0003] At present, most air-flow drying machines generally use PID controllers to adjust the water addition according to the difference between the outlet moisture and the set value. The contro...

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Problems solved by technology

Since the working medium of the airflow drying machine is high-temperature gas, the change of temperature and humidity and the hysteresis of control all have an adverse effect on the stability of the outlet moisture, resulting in large fluctuations in the outlet moisture

[0003] At present, most air-flow drying machines generally use PID controllers to adjust the water addition according to the difference between the outlet moisture and the set value. The control method is relatively simple, and there are two defects: one is the no-load stage before feeding, only Considering whether the temperature of the process gas reaches the set value, if the relative humidity of the process gas is not controlled, it is easy to cause the outlet moisture to deviate from the set value in the initial stage of feeding, and it takes a long adjustment time to return to normal. According to the flow calculation, the weight of the "tide head" or "dry head" of shredded tobacco is about 120Kg

The second is the loading stage after feeding, the loading of control water is only adjusted according to the change of outlet moisture, and the influencing factors of process gas temperature are not introduced, which may easily cause the outlet moisture curve to appear similar to the reverse fluctuation of process gas temperature.

In order to solve this problem, many enterprises install flow cooling equipment (VAS) at the outlet of the airflow drying machine, and adjust the stability of tobacco moisture by adding post-processing procedures, which can reduce the standard deviation to about 0.20, but this method has not Directly improve the moisture control ability of the airflow drying machine, and at the same time, the equipment transformation needs to change the original process layout, which also increases the production cost of the enterprise

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