Development of the hottest high-precision barreled

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Development of high-precision barreled liquid filling production line

Abstract: This paper mainly introduces the application of mass flowmeter in barreled liquid filling line and the characteristics of the whole automatic filling production line

key words: mass flowmeter; High precision measurement; Barreled; Filling production line; Control system

1. Preface

the filling of barreled liquid is very common in the chemical and food industry. For the filling volume above medium (above 10kg), the filling method is generally electronic weighing type and flowmeter type. Among them, the electronic weighing method has been widely used in China. Due to the development of flowmeter technology, especially the successful experience of mass flowmeter measurement in recent years, We believe that it is more reasonable to use mass flowmeter for high-precision filling with medium capacity and above. Now we introduce an automatic production line developed by us freely, which uses mass flowmeter for high-precision measurement of strongly corrosive viscous liquid. This line covers almost all aspects of the functions of barreled liquid filling line, which is of typical significance

2. Overview of filling production line

2.1 material characteristics and process conditions

1) filling material temperature: 5 ~ 35 ℃

2) material density: organic acid about 1.2g/cm3, organic acid salt about 1.3g/cm3

3) material viscosity: organic acid about 50CP, organic acid salt about 150cp

4) inlet pressure of feed pipe: ≥ 0.2MPa, fluctuation range ± 10%

5) the whole device meets GMP health requirements

filling capacity: 25L (square barrel); 200L (barrel); 1000L (IBC barrel)

filling accuracy: (quality accuracy): 0.1%, filling accuracy in line with European "OIML R 1996 issue" standard

filling speed: 25L barrel (30kg): 6 barrels/minute; 200L barrel (250 kg): 1 barrel/minute; 1000L barrel (1200 kg): 1 barrel/4 minutes

2.2 process flow

empty barrel finishing - empty barrel entering the filling station - Detection and positioning - filling head falling - filling valve opening - filling - quality measurement - reaching 90% × (set value - compensation value) - the flow of the regulating valve section is small - up to 100% × (set value - compensation value) - filling valve closing - vacuum adsorption - full barrel out of the filling station - steering - hanging cap - screwing cap - Labeling - stacking - winding - finished product output

2.3 overview of the filling system

the whole filling system includes mass flowmeter, control valve, filling head, support, guide rail, pneumatic actuator Control system and other components (see the schematic diagram)

(1) filling system accuracy

filling system accuracy mainly depends on the accuracy of mass flowmeter, filling speed and system stability

(2) over flow control

during filling, the actual filling volume must be greater than the set flow of the mass flowmeter. The PLC program must be set to require the flowmeter to send a signal in advance to control the closing of the filling valve, so as to ensure that the actual filling volume is consistent with the set volume of the mass flowmeter

(3) flow control (filling speed control)

in order to ensure the accuracy of the filling system, the filling speed of the filling system is designed as speed two, and the flow control valve automatically controls the filling speed by controlling the flow. Since the precise opening of the control valve will not affect the filling accuracy, using the automatic control valve in the current market is expensive and bulky, inconvenient to install and needs to increase the control requirements, so the flow control valve adopts a self-designed three position butterfly valve, that is, the maximum opening (fully open), 1/3 opening (can be manually set and adjusted), fully closed, which has outstanding advantages and stable performance

(4) drip proof

after filling, it takes a certain time for the viscous materials remaining on the surface of the filling head to flow out, so that the materials will drip onto the surface of the container and cause pollution. The vacuum generator back suction system is used in the design of the filling system to ensure no drip leakage. The vacuum generator has the advantages of large suction flow, simple structure, low cost, fast vacuum generation and removal, and convenient installation and maintenance

(5) filling head

the filling valve of the filling head adopts a self-designed pneumatic stop valve, which is simple in structure, quick in opening and closing, easy to clean and well sealed. The sealing with fluororubber meets the food grade

2.4 flowmeter selection

there are many kinds of flowmeter. The selection of flowmeter is mainly determined by material characteristics and on-site process conditions. Generally, only mass flowmeter can be selected for filling with high accuracy requirements

the metering system of a mass flowmeter includes a sensor and a transmitter for signal processing. Mass flowmeter is based on Newton's second law: force = mass × Acceleration (f=ma)

as shown in Figure 2, when the particle with mass m makes an angular velocity to the P axis with velocity V ω When the rotating pipe moves, the particle is subjected to the acceleration and force of two components:

(1) normal acceleration, that is, centripetal acceleration α r. Its magnitude is equal to 2 ω r. Towards the P-axis

(2) tangential angular velocity α t. That is, Coriolis acceleration, which is equal to 2 ω 5. Direction and α R vertical. Due to the compound motion, the α Coriolis force acting in t direction fc=2 ω VM, the pipeline acts a reaction on the particles, which makes the study of material properties reach a new height. Directional force -fc=-2 ω Vm。

when the density is ρ When the fluid flows at a constant speed V in a rotating pipe, any length Δ The pipe of X will be subjected to a tangential Coriolis force Δ Fc:

Δ Fc=2 ω V ρ A Δ X (1)

where, a - the flow cross-sectional area of the pipeline

due to the relationship: MQ= ρ Va

so: Δ Fc =2 ω qm Δ X (2)

item 3. The pendulum of the tensile testing machine returns too fast or too slow

therefore, the mass flow can be measured by directly or indirectly measuring the Coriolis force of the fluid flowing in the rotating tube

there are Emerson, e+h, KROHNE and other mass flowmeters with good comprehensive performance. For the design flow of the existing filling system, the measurement error of the flowmeter itself consists of two parts: nominal measurement error and zero stability error, that is, the maximum measurement error = nominal measurement error ± zero stability error

the accuracy of flowmeter is the most critical factor for the filling accuracy of the whole filling system. Considering the whole filling system, it is very important to select a mass flowmeter with high accuracy, good repeatability and stable performance to ensure that the system meets the design requirements

2.5 control system composition and control scheme

2.5.1 control system composition, see Figure 3

Figure 3 automatic control system composition

2.5.2 control scheme description

in order to reduce field wiring as much as possible, make the system more reasonable, more complete in function, and more convenient in operation, set up an mb+ master station at plc1, and set up several mb+ sub stations at the place where the input and output equipment on the production line is concentrated, as shown in the above figure

due to the extremely high requirements for the filling accuracy of the system, if the general flow meter and analog quantity are used, but the gold testing machine heavily relies on imported data acquisition and calculation, it will not meet the use requirements. Therefore, in the scheme design, in addition to selecting the mass flow meter of international famous brand as the measuring instrument, In addition, the most advanced quantum series products of Schneider company in the world are used as the main controller on the data acquisition and control terminal; In order to quickly collect the frequency output pulses of 12 mass flow meters, three high-speed counting modules (5 channels/module, 100kHz) are configured, which have fast collection speed and simple and convenient hardware configuration

3 characteristics of the whole production line

(1) the main material of the whole line is 316L, and the fluid seal adopts EPDM, which meets the requirements of strong corrosion prevention and food grade

(2) high degree of automation and advanced control technology

(3) the filling speed of mass flowmeter is nearly twice that of electronic weighing type

(4) the filling accuracy of mass flowmeter is higher than that of electronic weighing type, up to 0.1%, and the positive and negative deviation can be set manually

(5) the equipment is simple, covers a small area, works reliably and has less maintenance

4 conclusion

for the high-precision filling of large volume liquid, using mass flowmeter to measure is a reliable and simple technical scheme. Compared with the electronic weighing type, it has higher filling accuracy and filling speed, and less investment. It is a filling technology worthy of promotion


[1]. Ji Gang Application skills of flow measurement instruments, chemical industry press, 2003

[2].emerson high precision elite product sample (end)

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