The batching process is an important part of chemical production. The quality control of batching quality is directly related to whether the downstream process can be carried out smoothly. If the quality of the formulated liquid does not meet the requirements, it will cause waste of raw materials and energy, and then affect it. The quality and productivity of the product, as well as the mismatch of ingredients in some important production positions, may even cause an accident in the entire production. Therefore, the quality control of the batching process should be given enough attention.

1 Traditional batching automation system

The automatic control of the ingredients commonly used in actual production is to measure the amount of material added by the flow meter, and then control the amount of each material according to the preparation ratio.

The principle is: when the batching starts, the flow accumulating controller controls the feed valve to open until the cumulative flow of the materials M1 and M2 reaches their respective set values, and closes the feed valve to complete the batching process. Flow meters are a key part of this system. Since the batching process needs to accurately measure the amount of each material, the first choice is to select a high-precision flow meter; secondly, the flow meter should be selected according to the physical characteristics and chemical characteristics of the material to select the appropriate flow meter. Usually the accuracy of the flowmeter will be affected by various objective factors, such as fluid state in the pipeline, material scaling, crystallization, temperature changes, and the presence of bubbles, which have different effects on the measurement accuracy of the flowmeter. In addition, the flow meter has a range of measurable flow rates, and the flow rate of the batching pipe varies greatly, which also reduces the accuracy of its use. It can be seen that it is difficult to control the batching by using a flow meter, and the control precision is not well guaranteed.

2 Automate batching with weighing instruments

The composition and working principle of the weighing instrument The weighing instrument usually consists of a load cell, a weighing transmitter and a weighing controller. The load cell is composed of a metal elastic member body and a resistance strain gauge connected thereto. Firstly, according to the preparation ratio, the addition amount of each material is set, and the feeding of various materials is sequentially performed by the weighing controller or the PLC, and the adding amount of the material is detected by the weighing instrument until the amount of the material reaches the set value. The feed valve of this material, after completing the addition of the material, enters the process of adding the next material until all the materials are added according to the set addition amount and the ingredients are finished.

Easy to debug, easy to expand, overcome zero drift, accurate, direct quality ratio, high reliability and other advantages.