CN108201798B - A high-precision online proportional mixing method for multiple liquids - Google Patents

Abstract

The invention discloses a high-precision online proportional mixing method for multiple liquids. The method is to add a return bypass at the end of the main conveying pipeline in each liquid output unit, and set a return proportional control valve on the return bypass, A liquid flow meter is set at the end of the output pipeline, and an output proportional control valve is set at the front end of the liquid flow meter. When starting the delivery of the liquid to be mixed, the return proportional control valve in each liquid output unit is set to the maximum opening. and the output proportional control valve to the preset opening, and 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 real-time flow ratio between the liquids to be mixed, and compares and re-adjusts the size with the predetermined mixing ratio value, thereby realizing the online high-precision mixing of various liquids, and has a wide range of applications.

Description

A high-precision online proportional mixing method for multiple liquids

technical field

The invention relates to a multi-liquid on-line proportional mixing system, in particular to a method for high-precision online proportional mixing of multi-liquids.

Background technique

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 in a certain proportion, and air is inhaled to form foam while spraying from a foam gun or a foam gun, which is sprayed on the surface of the burning object to form a covering layer, so as to achieve the purpose of fire fighting. The foam proportioning 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 fighting fires. In addition, in the oil refining, chemical, pharmaceutical, beverage and other industries, mixing of various liquids is also an essential procedure, and it is also a very important part of the production process. Accurate proportioning and reliable control are the production requirements that must be met.

In the prior art, there have been reports on the control method and system technology for proportional mixing of multiple liquids, for example: Chinese patent application CN201380010494.5 provides a proportional mixing system and method, 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 master liquid is delivered to the mixer from the master liquid pump via the master liquid pipeline, and the slave liquid is delivered from the slave liquid pump through the slave liquid pump connected to the master liquid pipeline. The liquid pipeline is transported to the main liquid pipeline and added to the main liquid. Although this invention uses the accumulated flow rate of the main liquid and the slave liquid, it is possible to recognize errors accumulated in the past, and at the same time, it can be The mixing ratio of the flow rates of the main liquid and the slave liquid is maintained at the predetermined mixing ratio as the target, and the on-line proportional mixing of various liquids is realized. When the delivery capacity of the liquid delivery pump is greater than that of the mixed flow, the pressure of the delivery pipeline will increase when the flow demand is small, which will cause the pressure relief valve to open to release part of the flow to achieve balance, while the pressure relief valve can only adjust the pressure. , the flow rate cannot obtain an equilibrium value, 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 liquid, the phenomenon is more obvious; especially for some low-speed, Pumps with large internal leakage cannot guarantee the accuracy of mixing ratio when the flow rate changes in a large range.

In general, single-channel control, that is, the method of controlling the flow only on the conveying pipeline, has the disadvantages of insufficient control range and limited accuracy improvement.

SUMMARY OF THE INVENTION

In view of the above problems existing in the prior art, the purpose of the present invention is to provide a high-precision online proportional mixing method for multiple liquids, so as to realize online high-precision proportional mixing of multiple liquids.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A high-precision online proportional mixing method for multiple liquids, comprising a controller, a mixing container and a plurality of liquid output units, each liquid output unit including at least a liquid source and a main conveying pipeline, the head end of the main conveying pipeline being connected to the liquid The end of the main conveying pipeline is divided into an output pipeline and a return bypass, the end of the output pipeline is connected with the mixing container, and a liquid flow meter is arranged at the end of the output pipeline, A backflow proportional regulating valve is arranged in the backflow bypass, an output proportional regulating valve is arranged at the front end of the liquid flowmeter, and the signal output end of the liquid flowmeter is in phase with the signal input end of the controller The signal output end of the controller is connected with the signal input end of the backflow proportional control valve and the output proportional control valve respectively; the method includes the following steps:

S1) start the transportation of each liquid to be mixed, and open the return proportional control valve in each liquid output unit to the maximum opening and the output proportional control valve to the preset opening;

S2) The controller first obtains the real-time flow value of each liquid delivered to the mixing container according to the liquid flow meter in each liquid output unit, and judges whether the real-time flow value of each liquid delivered to the mixing container is within the preset flow range, and if the judgment result If no, then judge whether the real-time flow value is greater than or less than the preset flow. If the judgment result is greater than, the controller will control the opening of the output proportional control valve corresponding to the liquid to decrease. If the judgment result is less than, the controller will Control the opening of the backflow proportional control valve corresponding to the liquid to decrease; if the judgment result is yes, wait to execute step S3);

S3) When the real-time flow rate of each liquid is within the preset flow rate range after the flow adjustment process in step S2), the controller calculates the real-time flow rate ratio between the liquids to be mixed according to the predetermined mixing target, and compares it with The predetermined mixing ratio value is compared, if the comparison result is greater than, the controller will control the opening of the output proportional control valve corresponding to the liquid in the ratio numerator to decrease or/and control the output corresponding to the liquid in the denominator of the ratio The opening of the proportional control valve is increased, if the comparison result is less than The opening of the proportional control valve decreases.

The conveying power of the liquid source is the pump power or the high pressure difference. When the pump power is the liquid conveying pump, the liquid conveying pump is connected to the controller with a bidirectional electrical signal. When the high pressure difference is determined by the high pressure When the liquid storage container is produced, a solenoid valve is provided at the liquid output port of the high-level liquid storage container, and the solenoid valve is connected with the controller in a two-way signal manner.

The output of the return bypass is preferably connected to the corresponding liquid supply container, but can also be connected to a separate liquid storage container.

In a preferred solution, the preset opening degree described in step S1) is 30% to 60% of the maximum opening degree.

In a preferred solution, the preset flow rate range described in step S2) is obtained by floating up and down the theoretical flow rate value according to the required mixing precision.

Compared with the prior art, the beneficial technical effects of the present invention are:

In the present invention, a return bypass is added at the end of the main conveying pipeline in each liquid output unit, a return proportional control valve is set on the return bypass, a liquid flow meter is set at the end of the output pipeline, and the liquid flow meter is located at the end of the liquid flow meter. The output proportional control valve is set at the front end. When starting the delivery of the liquid to be mixed, first set the return proportional control valve in each liquid output unit to the maximum opening and the output proportional control valve to the preset opening, and then collect the real-time The flow value is compared and adjusted with the preset flow, and when the real-time flow value of each liquid is adjusted to within the preset flow range, the ratio of the real-time flow between the liquids to be mixed is also calculated according to the predetermined mixing target, and is compared with the preset flow rate. The predetermined mixing ratio value is compared and re-adjusted, which not only ensures the stable output of each liquid, but also can respond quickly to the change of flow rate, so that each liquid can be output stably according to the preset flow rate, and the accuracy of the mixing ratio is high. , which can meet the online high-precision mixing requirements of various liquids, has a wide range of applications, and has obvious progress and practicability.

Description of drawings

1 is a schematic structural diagram of a hybrid system involved in an embodiment of the present invention;

2 is a schematic diagram of the connection structure of the controller in the embodiment of the present invention;

FIG. 3 is a schematic flow chart of realizing high-precision online proportional mixing of multiple liquids according to an embodiment of the present invention.

3A, A liquid output unit; 31A, A liquid source; 311A, A liquid storage container; 312A, A liquid delivery pump; 313A, A input pipeline; 32A, A main conveying pipeline; 33A, A output pipeline; 34A, A return bypass; 35A, A liquid flow meter; 36A, A return proportional control valve; 37A, A output proportional control valve; 3B, B liquid output unit 31B, B liquid source; 311B, B liquid storage container; 312B, B liquid delivery pump; 313B, B input pipeline; 32B, B main delivery pipeline; 33B, B output pipeline; 34B, B return bypass; 35B , B liquid flow meter; 36B, B return proportional control valve; 37B, B output proportional control valve.

Detailed ways

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Example

Please refer to FIG. 1 and FIG. 2 : the system for realizing multi-liquid online proportional mixing in this embodiment includes a controller 1, a mixing container 2 and two liquid output units 3A/3B (two are used as examples in this embodiment, but Not limited to 2, the specific number is determined according to the type of liquid to be mixed, each liquid to be mixed corresponds to one liquid output unit), and each liquid output unit 3A/3B includes at least a liquid source 31A/31B and a main delivery pipeline 32A /32B, the liquid source 31A/31B described in this embodiment includes a liquid storage container 311A/311B and a liquid delivery pump 312A/312B, and the liquid storage container 311A/311B is connected to the liquid delivery pump 312A through the input pipeline 313A/313B /312B, the output end of the liquid delivery pump 312A/312B is connected with the head end of the main delivery pipeline 32A/32B, and the end of the main delivery pipeline 32A/32B is equally divided into an output pipeline 33A/ 33B and the return bypass 34A/34B, the end of the output pipeline 33A/33B is connected with the mixing container 2, and the liquid flow meter 35A/35B is provided at the end of the output pipeline 33A/33B, and the return A return proportional control valve 36A/36B is provided on the bypass 34A/34B, an output proportional control valve 37A/37B is provided at the front end of the liquid flow meter 35A/35B, and the signal output end of the liquid flow meter 35A/35B It is connected with the signal input end of the controller 1, and the signal output end of the controller 1 is respectively in phase with the signal input end of the backflow proportional control valve 36A/36B and the signal input end of the output proportional control valve 37A/37B. connect.

Referring to Figure 3, the present invention adopts the above-mentioned system to realize high-precision online proportional mixing of multiple liquids, comprising the following steps:

S1) Start the delivery of the liquids A and B to be mixed (ie: start the A, B liquid delivery pumps 312A, 312B), and open the return proportional control valves 36A, 36B in each liquid output unit 3A, 3B to the maximum opening and output Proportional regulating valves 37A, 37B to a preset opening degree (the preset opening degree is between 0 and 100%, preferably between 30% and 60% of the maximum opening degree);

S2) The controller 1 first obtains the real-time flow value of each liquid delivered to the mixing container 2 according to the liquid flow meter 35A/35B in each liquid output unit 3A/3B, and judges whether the real-time flow value of each liquid delivered to the mixing container 2 is within Within the preset flow range (the theoretical flow value is obtained by floating up and down according to the required mixing accuracy), if the judgment result is no, then judge whether the real-time flow value is greater or less than the preset flow rate, if the judgment result is greater than, the controller 1 will control The opening of the output proportional control valve 37A/37B corresponding to the liquid decreases, if the judgment result is less than, the controller 1 will control the opening of the return proportional control valve 36A/36B corresponding to the liquid to decrease; If yes, wait to execute step S3);

S3) When the real-time flow rate of each liquid is within the preset flow rate range after the flow adjustment process in step S2), the controller 1 calculates the real-time flow rate ratio between the liquids to be mixed according to the predetermined mixing target (for example, : QA:QB), and compare with the predetermined mixing ratio value, if the comparison result is greater than, then the controller 1 will control the opening of the output proportional control valve 37A corresponding to the A liquid in the ratio molecule to decrease or/or and control the opening of the output proportional control valve 37B corresponding to the B liquid in the denominator of the ratio to increase, if the comparison result is less than, then the controller 1 will control the opening of the output proportional control valve 37A corresponding to the A liquid in the ratio numerator. increase or/and control the opening of the output proportional control valve 37B corresponding to the B liquid in the denominator of the ratio to decrease.

In addition, it should be noted that the conveying power of the liquid source 31A/31B can also be a high-level pressure difference. For example, a high-level liquid container is used, so that the liquid stored in the high-level container is input to the main conveying pipeline 32A/32B through the level difference ; In order to accurately control the input operation of the liquid, a solenoid valve can be set at the liquid output port of the high-level liquid storage container, so that the solenoid valve is connected with the controller in a two-way signal, and the intelligent switching of the liquid and the transmission of the liquid can be realized through the controller. flow.

The output of the return bypass 34A/34B can also be connected to a separate liquid storage container.

To sum up, in the present invention, a return bypass is added at the end of the main conveying pipeline in each liquid output unit, a return proportional control valve is set on the return bypass, and a liquid flow meter is set at the end of the output pipeline. The front end of the liquid flow meter is provided with an output proportional control valve. When starting the delivery of the liquid to be mixed, first set the return proportional control valve in each liquid output unit to the maximum opening and the output proportional control valve to the preset opening, and then pass the Collect the real-time flow value of each liquid, compare and adjust it with the preset flow, and calculate the real-time flow between the liquids to be mixed according to the predetermined mixing target when the real-time flow value of each liquid is adjusted within the preset flow range It not only ensures the stable output of each liquid, but also can respond quickly to changes in flow rate, so that each liquid can be stably output according to the preset flow rate, and The mixing ratio has high precision, can meet the online high-precision mixing requirements of various liquids, has a wide range of applications, and has obvious progress and practicability.

Finally, it is necessary to point out here: the above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this, and any person skilled in the art is within the technical scope disclosed by the present invention. Any changes or substitutions that can be easily thought of within the scope of the present invention should be covered within the protection scope of the present invention.

Claims (6)

1. A method for high-precision online proportional mixing of multiple liquids, comprising a controller, a mixing container and a plurality of liquid output units, each liquid output unit at least comprising a liquid source and a main conveying pipeline, the head end of the main conveying pipeline Connected with the liquid source, the end of the main conveying pipeline is divided into an output pipeline and a return bypass, the end of the output pipeline is connected with the mixing container, and the end of the output pipeline is provided with a liquid flow A backflow proportional control valve is provided in the backflow bypass, an output proportional control valve is provided at the front end of the liquid flowmeter, and the signal output end of the liquid flowmeter and the signal input of the controller The signal output end of the controller is connected with the signal input end of the backflow proportional control valve and the output proportional control valve respectively; it is characterized in that, the method includes the following steps: S1) start the transportation of each liquid to be mixed, and open the return proportional control valve in each liquid output unit to the maximum opening and the output proportional control valve to the preset opening; S2) The controller first obtains the real-time flow value of each liquid delivered to the mixing container according to the liquid flow meter in each liquid output unit, and judges whether the real-time flow value of each liquid delivered to the mixing container is within the preset flow range, and if the judgment result If no, then judge whether the real-time flow value is greater than or less than the preset flow. If the judgment result is greater than, the controller will control the opening of the output proportional control valve corresponding to the liquid to decrease. If the judgment result is less than, the controller will Control the opening of the backflow proportional control valve corresponding to the liquid to decrease; if the judgment result is yes, wait to execute step S3); the preset flow range is obtained by floating up and down the theoretical flow value according to the required mixing accuracy; S3) When the real-time flow rate of each liquid is within the preset flow rate range after the flow adjustment process in step S2), the controller calculates the real-time flow rate ratio between the liquids to be mixed according to the predetermined mixing target, and compares it with The predetermined mixing ratio value is compared, if the comparison result is greater than, the controller will control the opening of the output proportional control valve corresponding to the liquid in the ratio numerator to decrease or/and control the output corresponding to the liquid in the denominator of the ratio The opening of the proportional control valve is increased, if the comparison result is less than The opening of the proportional control valve decreases. 2 . The method according to claim 1 , wherein the conveying power of the liquid source is pump power or high pressure differential. 3 . 3 . The method according to claim 2 , wherein when the pump power is a liquid delivery pump, the liquid delivery pump is connected with the controller in a bidirectional electrical signal. 4 . 4. The method according to claim 2, wherein: when the high-level pressure difference is generated by a high-level liquid storage container, a solenoid valve is provided at the liquid output port of the high-level liquid storage container, and the solenoid The valve is bidirectionally signally connected to the controller. 5. The method according to claim 1, wherein the output end of the return bypass is connected to a liquid storage container. 6 . The method according to claim 1 , wherein the preset opening degree in step S1 ) is 30% to 60% of the maximum opening degree. 7 .

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