A high-precision online proportional mixing method for multiple liquids

Abstract

The invention discloses a high-precision online proportional mixing method for multiple liquids. The method is to add a backflow bypass at the end of the main conveying pipeline in each liquid output unit, and set a backflow proportional regulating valve on the backflow bypass. Set a liquid flow meter at the end of the output pipeline, and set an output proportional regulating valve at the front end of the liquid flow meter. When starting the delivery of the liquid to be mixed, first make the return proportional regulating valve in each liquid output unit to the maximum opening And output the proportional control valve to the preset opening, then collect the real-time flow value of each liquid and compare and adjust it with the preset flow, and when the real-time flow value of each liquid is adjusted to the preset flow range, also according to The predetermined mixing target calculates the ratio of the real-time flow rate between the liquids to be mixed, and compares and adjusts the value with the predetermined mixing ratio value, thereby realizing the online high-precision mixing of various liquids and having a wide range of applications.

Description

technical field [0001] The invention relates to a multi-liquid on-line proportional mixing system, in particular to a method for high-precision on-line proportional mixing of multi-liquids. Background technique [0002] With the gradual development of the fire protection industry, there are more and more types of foam liquids suitable for Class A and Class B fires. When in use, the foam liquid and water are mixed according to a certain ratio, and when the foam gun or foam gun is sprayed, air is sucked in to form foam, which is sprayed on the surface of the burning object to form a covering layer, so as to achieve the purpose of fire extinguishing. The foam proportional mixer is the "nerve center" of the foam fire extinguishing system, and its working performance is directly related to the success or failure of the foam fire extinguishing system in extinguishing fires. In addition, in oil refining, chemical, pharmaceutical, beverage and other industries, the mixing of variou...

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Problems solved by technology

[0003] In the prior art, there have been reports on control methods and system technologies for proportional mixing of various liquids. For example, a proportional mixing system and method are provided in Chinese patent application CN201380010494.5. The proportional mixing system is to mix the main liquid and A system in which the slave liquid is mixed according to a predetermined mixing ratio. The main liquid is delivered to the mixer from the main liquid pump through the main liquid pipeline. The liquid pipeline is sent to the main liquid pipeline and added to the main liquid, although the invention can recognize the error accumulated retrospectively by using the accumulated flow of the main liquid and the secondary liquid, and can Keeping the mixing ratio of the flow rate of the main liquid and the secondary liquid at the predetermined mixing ratio as the target realizes the online proportional mixing of various liquids, but since the main liquid and the secondary liquid are both delivered and adjusted by the pump, when The delivery capacity of the liquid delivery pump is greater than the mixed flow rate. When the flow demand is less, the pressure of the delivery pipeline will increase, which will cause the pressure relief valve to open and release part of the flow to achieve balance, while the pressure relief valve can only adjust the pressure. , and cannot obtain a balanced flow rate, which makes it difficult to guarantee the mixing accuracy of this system, especially when the ratio value changes greatly, and the flow rate changes from large to small liquids, this phenomenon is more obvious; especially for some low-speed, For pumps with large internal leakage, when the flow rate changes in a large range, the accuracy of the mixing ratio cannot be guaranteed at all.

[0004] Generally speaking, the single-channel control, that is, the method of controlling the flow only on the delivery pipeline, has the disadvantages of insufficient control range and limited accuracy improvement

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