SU1283616A1 - Device for measuring density of liquid - Google Patents

Abstract

The invention relates to pneumatic devices for measuring the density of liquids and suspensions and ms set to be used in chemical, pulp and paper, microbiological and other industries. The purpose of the invention is to improve the measurement accuracy and expand the functional capabilities of the device. The device contains upper and lower membrane sensors, a pressure follower with a shift, consisting of a reference element and a pressure sensor, a reference element, a unit for multiplying the difference of signals by a constant coefficient and a measuring device. The pressure P of the lower sensor is supplied to a reference element in which the signal is doubled and the signal is subtracted from it (P a +) where P is the pressure of the upper sensor; Pjj is the shift pressure from the output of the reference element. The difference in the signals of the RE 2P signals, - (P, j + g) supplies, from the upper sensor, to the positive input of the multiplication unit, to the negative input of which g comes. In the block, the difference between the signals from the output of the reference element and the upper sensor is multiplied by the coefficient K. From the block, the signal enters the meter-g meter. 1 PC. to 00 with od oh)

Description

The invention relates to pneumatic devices for measuring the density of liquids and suspensions during their processing in the chemical, pulp and paper, microbiological and other industries.

The aim of the invention is to increase the measurement accuracy and enhance the functionality of the device.

The drawing shows a device for measuring the density of a liquid.

The device consists of an upper sensor 1, a lower sensor 2, a pressure transducer with a shift consisting of a comparison element 3 with a setting device 4, a comparison element 5, a multiplication unit 6 consisting of a summing block with constant and variable throttles, and device 7.

The output of the upper sensor 1 is connected to the positive input of the comparison element 3 and the negative input of the multiplication unit 6. The second positive input of the reference element 3 is connected to the shift pressure setting device 4.

The output of the lower sensor 2 is connected to two positive chambers of the comparison element 5, the code of which is connected to the positive input of the multiplier 6

The output of the multiplier is connected to the measuring device 7.

The device works as follows.

When sensors are installed on a vessel with a controlled fluid, the density of which varies from / to

P, (kg / m) The pressure P at the output of sensor 1 is fed to the input of the comparison element 3, where it is added to the shear pressure P.

The pressure P of the lower sensor 2 goes down on the comparison element 5, in which the signal doubles and the signal (P + h) coming from the output of the comparison element 3 is subtracted from it

Signal difference

РЗ

2P. - (Ra

)

is fed to the positive input of the multiplication unit 6, the negative input of which receives the signal P from the upper sensor 1.

In block 6, the difference between the signals from the output of the comparison element 5 and the upper sensor 1 is multiplied by a factor K.

The pressure at the output of block 6 is equal to, P (P, - Pj) - P, a,

is fed to the input of the measuring device 7.

The pressure measured by sensors 1 and 2, respectively, is:

sensors with pneumatic transducers, h, h is the upper limit of the column of controlled liquid acting respectively on sensors 1 and 2.

20

The shear pressure when operating under the doubling and multiplying scheme by K is determined from the conditions:

P, O nP "P" "

25

then 2 (P –P J – P

SE

ABOUT,

then

Rsa

2i§

Q

I.)

thirty

35

where a () is the base of measurement, Mj p is the density of the solvent, kg / m.

The coefficient K is determined from the condition P 1 kgf / cm at the upper value of the density measurement range, i.e.

40

R -

 1f p.-f;)

then

TO

1 h

2-0.8 Q ()

45 Considering that 2 - b and (L - h,)

P -rt1

 .V

 Q constant, the signal arriving at the input of the measuring device 7, is proportional to the change in the density of the controlled fluid

50

R

K-a-b (P-I,).

Example. When the level of lightness above the upper sensor is 500 mm, the base of measurement is 3500 mm, the pressure above the fluid is 1 kgf / cm PO and the pressure measurement range is 1000-1400 kg / m pressure at the bottom

and upper sensors are respectively equal to:

R 1.4 kgf / cm, Ru 1.05 kgf / cm,

Therefore, it is necessary to select a membrane pressure sensor with an upper measurement limit of 1.6-gf / cm as the sensor.

In the case of using the known device at R 1400 kg / m

P p p p (p-p)

Sbix 1 3 3 ho

ABOUT

 700 kg / m or 0.07 kg / cm.

 In case of using the proposed device

Р 2К 2i§ -. (Р р) 7 1Л

   j ,. Hz, Hn -

then PO., V 9996 kg / m or 1 kg / cm,

out

0.8

In the first case P, O p

 q

 1750 0.175 kg / cm, which is greater than the allowable shear pressure for repeater II2P2.

p In the second case, R h 2-R,

 By

 3500 kg / m or 0.35 kg / cm2, which is 35% of the shear pressure for a repeater consisting of

0

five

0

five

0

comparing and setting the pressure applied in the described device.

Claims (1)

Invention Formula A device for measuring the density of a fluid, containing upper and lower diaphragm sensors with transducers immersed in a controlled fluid, a pressure repeater with a shift, the input of which is connected to the output of the upper membrane sensor, and the output of the negative control chamber of the reference element, the first five chamber of which connected to the output of the lower diaphragm sensor, and a measuring device, about T characterized by the fact that, in order to increase the accuracy of measurement and expand the functional capabilities of the device, into it an additional unit for multiplying the difference of signals is introduced, the PLUS-1 camera is connected to the output of the reference element, the negative camera is connected to the output of the upper membrane sensor, and the output is connected to the measuring device, and the code of the lower membrane sensor is additionally connected to the second positive camera of the comparison element, and the shift repeater is made as a comparison element, the second plus chamber of which is connected to the output of the pressure control unit,