Instrumentation for level, density or interface measurement of two liquids

Abstract

The invention discloses a meter used for liquid level, density measurement and measurement of an interface of two kinds of liquid. The meter comprises a drum, a sinker, and magnetic steel and furthercomprises a force sensor, a concave framework and a steel wire rope connecting to the force sensor and the concave framework. The sinker is disposed inside the drum and the magnetic steel is disposedoutside the drum. The magnetic steel is magnetically coupled to the sinker. With the meter, it is no longer difficult to measure liquid level or density in a high-temperature high-pressure medium or ahigh-pressure low-density medium and a high-pressure low-temperature low-density medium. The meter is high in measurement precision, simple in structure, low in manufacture and maintenance cost and convenient to use so that the meter is used widely.

Description

technical field [0001] The invention relates to an instrument for measuring liquid level, density or interface of two liquids. Background technique [0002] The existing liquid level, density or two kinds of liquid interface measuring instruments are of great variety and variety, each has its own advantages and disadvantages. for example: [0003] Patent No. CN86101109 discloses a large-scale and high-precision liquid level automatic display device: the roller pulley moves up and down on the float along the guide rail, and the spotlight on the float illuminates the photosensitive element to realize on-site indication and remote transmission. Its advantage is that it avoids the friction caused by the magnetic coupling force, and its disadvantages include: 1. The circuit structure for power supply to the spotlight is complicated; It cannot be used. When running up and down, the brush will carry medium from the guide rail to the float; 3. The elastic insulating ring has aging...

AI Technical Summary

Problems solved by technology

Its advantage is that it avoids the friction caused by the magnetic coupling force, and its disadvantages include: 1. The circuit structure for power supply to the spotlight is complicated; It cannot be used. When running up and down, the brush will carry medium from the guide rail to the float; 3. The elastic insulating ring has aging problems, which affects reliable use; 4. The elastic insulating ring, spotlights and light-transmitting plates exist in the float chamber, so that Its use is limited in high temperature and high pressure occasions; 5. The power supply to the spotlight and the power supply to the photosensitive element belong to two circuits, and the float measurement and the photosensitive element are respectively independent, that is, the magnetic float uses pulleys and tracks, and the remote sensor uses A set of fixed brackets makes the structure complicated; 6. Roller pulleys and spotlights are placed on the float, which further increases the quality of the float, and then needs to increase the volume and thickness of the float and the float chamber shell. In this case It is not suitable for low-density and high-pressure occasions; 7. The surface of the spotlight is easy to form a water film or the dust on the photosensitive element will affect the use; 8. There is no good on-site indication, which is not convenient for visual inspection; 9. The signal is not continuous; 10. There are many internal parts in the float chamber shell, and when it is used in strong corrosive media, all the internal parts must be made of expensive corrosion-resistant materials, resulting in high cost

[0004] Patent ZL89210640.9 discloses a float and trolley magnetically coupled liquid level indicator alarm, which uses rolling friction to reduce friction, and its shortcomings include: 1. The signal remote transmission part needs to add a slider with a skeleton The movable arm of the wire resistor and the sliding wire resistor makes the structure complicated and increases the friction; 2. The local indication is not clear; 3. Although it is mentioned that the float is simple as a ball, when the float is made of non-ferromagnetic material , the ferromagnetic material is embedded in the waterline or equatorial zone, which will form sliding friction and cause a large friction force. It can be seen that the inventor may have overlooked the fact that the spherical float is simple to manufacture and the ferromagnetic material is embedded in the horizontal line or equatorial zone. The influence of the shape of the float on the friction force; and as mentioned in ZL97225950.3, there are still problems such as large friction force, unreliable use of magnetic flip parts, and complicated circuits.

Both high and low temperature make the resistance change affect the accuracy; 2. The float with the guide rod hole in the middle is not resistant to high pressure; 3. If the local indication is realized, another set of connecting pipes is needed; 4. The float is easy to be stuck; 5. Use The reed switch has many components, is unreliable, and the signal is discontinuous; 6. Two spiral tube resistance wires are adjacently wound on the insulator, too dense and easy to short circuit, too sparse will affect the accuracy, and there are conductive impurities in the manufacturing and assembly When it enters at the same time, it is easy to cause a short circuit. When the winding is too sparse, it may not work properly due to the point contact of the ball; 7. It is possible to stop the work during maintenance; Such as a heat exchanger; 9. The signal of the sensor fluctuates and jumps, that is, the signal is discontinuous; 10. The float and the guide rod are sliding friction, the friction force is large, and the display lags

[0008] Another patent ZL98229246.5 also discloses a resistive liquid level sensor. Its advantage is that it does not require magnetic sensitive elements, which greatly improves reliability, but it also has shortcomings: 1. The resistor is placed in the sensor tube, It cannot be used in high temperature places; 2. The float and shell of this structure are not resistant to high pressure (the internal pressure of the tube is greater than the external pressure); 3. The weight of the float increased by the magnetic trolley is not conducive to use in high temperature and high pressure or high pressure and low density occasions; 4. The signal is discontinuous; 5. There is no on-site indication, and if the local indication is added, an additional mechanism is required; 6. The structure of the magnetic trolley is complicated; 7. The distance between the magnetic guide sheet and the magnetic steel is long, and the suction force is reduced; 8 . Some occasions with internal parts in the container cannot be applied, such as heat exchangers; 10. The float and the guide rod are sliding friction, the friction force is large, and the display lags behind

[0013] 1. The remote transmission signal is not continuous;

[0014] 2. There are many precious metals or corrosion-resistant materials (pulleys, bearings, float chambers, etc. need to be selected according to process conditions, such as high temperature and corrosion), which further increases the manufacturing cost;

[0015] 3. Higher working pressure or high pressure and low density occasions are difficult to apply;

[0016] 4. The counterweight (or counterweight) is immersed in the liquid to affect the accuracy;

[0017] 5. Difficulty in assembly and calibration;

Some structures are huge, which increases the burden of packaging and transportation;

[0019] 7. There are many friction pairs or there is sliding friction between the float and the pipe wall, resulting in high friction (steel-to-steel sliding friction coefficient μ is 0.15, steel-to-steel cylindrical radial rolling friction coefficient is 0.05, spherical steel balls to steel The coefficient of friction is less than 0.003

Vibration frequency method is expensive and cannot be used in occasions with high temperature or pressure

[0026] Another example is the pressure density bottle for measuring the density of liquefied petroleum gas as described in ZL01260282.3. Although it solves the measurement of the density of liquefied petroleum gas, it cannot be used online

[0027] Another example is a precision density meter described in ZL02218097.4, which can only be used in atmospheric pressure vessels

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