RU2122196C1 - Device measuring density of liquid media - Google Patents

Abstract

FIELD: measurement technology, systems controlling manufacturing processes, measurement of density and level of drilling fluid and cement mortars. SUBSTANCE: device has source 5 of compressed air, two piezometric tubes 1 and 2 which one ends are submerged into tested liquid to different depth and converter 18 of difference of pressures in piezometric tubes 1 and 2 to proportional electric signal. Ends of piezometric tubes submerged into liquid are fitted with fluoroplastic end pieces 3 and 4. Outlet of source 5 of compressed air is connected with conduits 6 and 7 through pneumatic valves 8 and 9 and permanent throttles 10 and 11 to inlet pipe unions 12 and 13 of piezometric tubes 1 and 2 and with conduits 14 and 15 through pneumatic valves 8 and 9 to control conduits. Outlet pipe unions 16 and 19 of piezometric tubes 1 and 2 are connected to blank chambers of converter 18 by means of conduits 17 and 20. Check of level in vessel performed by measurement of depth H₁ of submersion of piezometric tube 1 below level of liquid. EFFECT: increased measurement accuracy and reliability of device. 1 dwg

Description

 The invention relates to the field of measuring equipment and can be used in process control systems, in particular for measuring the density and level of drilling and cement solutions.

 A device for measuring the density of liquid media, such as drilling and cement mortars. The device allows to exclude losses in the pulse tubes of the converter (differential pressure gauge), to reduce the error that occurs due to the buildup of mechanical impurities on the sensitive elements of the pressure recorders and to provide thermal compensation in solutions with changing temperature (A.S. N 1374097, class G 01 N 9/26, 1988).

 The disadvantage of this device is the complexity of the design and its settings.

 The closest technical solution to the proposed one is the pneumatic electric densitometer adopted as a prototype, containing two piezometric tubes immersed in a reservoir with a controlled liquid at different depths, a differential pressure gauge with a transducer and a secondary device, and the transducer has a design that allows to increase the measurement accuracy (A.S. N 763742, CL G 01 N 9/26, 1980). The device has a relatively simple design, but does not allow it to be used to measure the density of liquid media such as drilling or cement mortars. The reason for this is two factors. Firstly, during the operation of the device, the particles of the solution stick to the end edges of the ends of the piezoelectric tubes immersed in the liquid, and secondly, when the source of compressed air is turned off, the solution flows into the pipes. Both factors cause an increase in the hydraulic resistance of the tubes and failure of the device.

 The objective of the invention is to expand the range of measured media, improving the accuracy of measurement and reliability of the device.

 The fulfillment of this task is achieved by the fact that in a device containing a source of compressed air, two piezometric tubes vertically installed in containers with liquid controlled, one ends of which are immersed in the liquid at different depths, and a pressure difference transducer in the piezoelectric tubes into a proportional electric signal immersed in the liquid ends of the piezometric tubes are equipped with tips with release coating (for example, fluoroplastic), the outlet channel of the compressed air source through a corresponding normally closed pneumatic valve and the corresponding constant throttle to the inlet tube and the respective piezometric with the corresponding pneumatic valve control channel and output fittings piezometric tubes through inertial units (constant restrictor and capacitance) connected to the input of said inverter deaf.

 The drawing shows a functional diagram of the proposed device.

 The device contains two piezometric tubes 1 and 2, immersed in a container with a controlled fluid at different depths. The submerged ends of the tubes are equipped with tips 3 and 4 with a release coating.

 The output channel of the compressed air source with 5 channels 6 and 7 is connected through pneumatic valves 8 and 9 and the constant chokes 10 and 11 with the inlet fittings 12 and 13 of the piezometric tubes 1 and 2. The control channels 14 and 15 of the pneumatic valves 8 and 9 are connected to the output channel of the compressed air source 5. The output nozzle 16 of the piezometric tube 1 through the first inertial link (throttle 17 and capacitance 18) is connected to the positive blind input 19 of the pressure difference transducer 24 in the piezometric tubes into a proportional electric signal, and the output nozzle 20 by a piezo the metric tube 2 through the second inertial link (inductor 21 and capacitance 22) is connected to the negative negative input 23 of the converter 24. The output electrical signal 25 of the converter 24 is an output device.

 A device for measuring density operates as follows.

When the compressed air source 5 is turned on, normally closed valves 8 and 9 are opened and the supply pressure from the source 5 is supplied through pneumatic valves 8 and 9 and constant chokes 10 and 11 to the inlet fittings 12 and 13 of the piezometric tubes 1 and 2. Moreover, on the positive (19) and negative (23) inputs of the transducer 24, excessive pressures P ₁ = ρgH ₁ and P ₂ = ρgH _{2 are created} , where ρ is the density of the liquid, g is the acceleration of gravity, H ₁ and H ₂ are the depths of immersion of the piezometric tubes under the liquid level. The pressure difference at the transmitter inputs ΔP = P ₁ - P ₂ = ρg (H ₁ - H ₂ ) = gρd (where d = H ₁ -H ₂ = const is a constant value) is proportional to the measured density ρ. Therefore, the output electrical signal of the converter 5 is also proportional to the density ρ.
The level in the tank is controlled by measuring the immersion depth H _{1 of the} piezometric tube 1 under the liquid level. For this, the negative input 23 of the transducer 24 communicates with the atmosphere, and the output fitting 20 of the piezometric tube 2 is muffled. When measuring the level, the value of H ₁ = P ₁ ρg, at a known density ρ, is converted into a proportional electrical signal, which is read from the output 25 of the converter 24.

 Inertial links (pos. 17 - 18 and 21 - 22) perform the function of smoothing out pressure pulsations in piezometric tubes 1 and 2, arising due to the separation of air bubbles from the lower end edges of tips 3 and 4.

 The presence of tips with a release coating on the ends of the piezometric tubes immersed in the liquid improves the accuracy of the measurement and the reliability of the device by eliminating the sticking of liquid particles to the end edges of the piezometric tubes.

 Thus, in the described device on the basis of the proposed technical solution can be provided with reliable measurement of the density and level of liquid media with sufficiently high accuracy.

Claims (1)

 A device for measuring the density of liquid media containing a source of compressed air, two piezometric tubes vertically installed in a container with a controlled liquid, the ends of which are immersed in the liquid at different depths, and a pressure difference transducer in the piezometric tubes into a proportional electrical signal, characterized in that the ends of the piezometric tubes in the liquid are equipped with tips with a release coating, the output channel of the compressed air source through the appropriate An abnormally closed pneumatic valve and a constant throttle are connected to the input fitting of the non-immersed end of the corresponding piezometric tube and to the control channel of the corresponding pneumatic valve, the output fittings of the piezometric tubes are connected through the first and second inertial links to the dead inputs of the specified converter, and the output of the converter is the output of the device.