Application of weighing instrument in automatic batching system

The batching process is an important link in chemical production. The quality of the batching is directly related to the smooth progress of the downstream process. If the quality of the formulated liquid does not meet the requirements, it will cause the waste of raw materials and energy in the light of the The quality and yield of the products, and the ingredient errors in some important production positions can even cause accidents in the entire production. Therefore, sufficient attention should be paid to the quality control of the batching process.

1 Traditional batching automation system

The common automatic control of ingredients in actual production is to use a flow meter to measure the added amount of materials, and then control the added amount of each material according to the mixing ratio.

The principle is: when the batching starts, the flow accumulation controller controls the feed valve to open until the cumulative flow of materials M1 and M2 reach their respective set values, close the feed valve to complete the batching process. The flow meter is the key link in this system. Since the batching process needs to accurately measure the amount of each material added, first select a high-precision flow meter; secondly, the selection of the flow meter should be based on the physical and chemical characteristics of the material to select the appropriate flow meter. Generally, the accuracy of the flow meter will be affected by various objective factors, such as the fluid state in the pipeline, material fouling, crystallization, temperature changes, and the presence of air bubbles, etc., all have varying degrees of impact on the measurement accuracy of the flowmeter. In addition, the flow meter has its measurable flow rate range, and the flow rate of the batching pipeline varies greatly, which also reduces the accuracy of its use. It can be seen that it is difficult to use a flow meter to achieve batching control, and the control accuracy cannot be well guaranteed.

2 Use weighing instrument to realize batching automation

The composition and working principle of weighing instrument usually weighing instrument consists of weighing sensor, weighing transmitter, weighing controller. The load cell is composed of a metal elastic element body and a resistance strain gauge connected to it. First, set the addition value of each material according to the preparation ratio, and the weighing controller or PLC will execute the addition of various materials in sequence. The weighing instrument detects the addition of this material until the addition of this material reaches the set value. The feed valve of this material enters the next material addition process after completing the addition of this material, until all the materials are added according to the set addition value to complete the batching.

It has the advantages of convenient debugging, easy expansion, overcoming zero drift, accurate and direct realization of quality ratio, and high reliability.