DE2250547B2 - Device for the continuous measurement of the viscosity, the consistency or the solids concentration of a liquid - Google Patents

Description

representation of a second embodiment of the measuring tube and

3 shows a graphic representation of the pressure conditions on the measuring transducer.

According to FIG. 1, the liquid first flows through the straight pipe section 2 of the measuring pipe designated as a whole by 1 in the direction of the arrow aa. A differential pressure arises at the points marked A and B , which depends on the viscosity and the speed of the liquid. After the straight pipe section 2, the pipe widens conically into a part 3 and then finally merges into another straight part 4. According to Bernouill's law, an increase in pressure occurs in expansion 3, which counteracts the differential pressure from the viscosity and material velocity and which can be measured at measuring point C.

According to FIG. 2, the measuring tube 5, the α also in the direction of the arrow flows through the liquid from a conically erweitern- ao the tube 6 with spaced-apart pressure measuring points D and E. The pressure conditions at the points D and E are the same as in FIG. 1 at points A and C.

In the graphic representation according to FIG. 3 it is shown that the differential pressure between the points A and C or D and E for a certain speed range is practically dependent only on the viscosity and not on the flow velocity and thus represents a direct measure for the desired measurement.

According to Biehl (1907, MHt. Research work, VDI, Issue 44, ZdVdI 1908, p. 1035; 1925, Techn. Mechanik, VDI-Verlag) the resistance figure is one Pipe with a smooth wall, for example for a pipe NW 100:

λ = 0.0126 + 0.0047-.
ν

It means

λ is the resistance figure,

& the toughness,

ν is the flow velocity.

The size of the differential pressure for a straight piece of pipe with length 1, through which a substance of viscosity χ flows, as a function of the speed is shown by curve I.

According to Bernouilli's law, the pressure increases at an expansion of a pipeline after the equation

It means

Δ Ρ is the differential pressure,
ρ is the specific mass of the substance,
v _o the speed before expansion,
V ₁ the speed in the expansion.

Curve II shows the size of the differential pressure resulting from the expansion.

The algebraic sum of curve I and curve II is represented by curve III. It can be seen that the differential pressure in the speed range M - N remains practically the same for the viscosity χ.

For this purpose 2 sheets of drawings

Claims (3)

1 2 of the measuring device have to be removed before the cleaning work begins. The removed parts must then be reassembled 1. Device for continuous measurement. the viscosity, the consistency or the solids- 5 From DT-AS 12 37 809 smd furthermore measuring pre-concentration of a liquid, in particular directions for non-Newtonian liquids in paper pulp, with one of the liquid whose consistency can be continuously flowed through, at least along of a TeU- is measured. For this purpose, the liquid flows through a measuring tube which expands in the direction of flow with a constant flow rate and has two pressure measuring points, »a plurality of pressure measuring points parallel to one another or one behind the other, one in the area of the lesser of the arranged, turbulence-free flow lines and the other in the area of the larger pipe sections, which are designed in such a way that there is a cross-section, characterized by a distinction from section to section that the expansion of the measuring tube (1; 5) licher course of the flow velocity is chosen so that the internal friction » 5 gradients in a pressure drop between the direction caused perpendicular to the flow direction of the liquid. These line sections see through the two measuring points (A, C; D, E) can be designed both cylindrically and conically in accordance with Bernoulli's equation. The liquid discharge lines, which are connected to these line sections within a certain pressure increase, as well as to the speed range approximately compensated- »o the line sections themselves are measuring devices. to obtain measurement numbers for the differences 2. Apparatus according to claim 1, characterized in that the pressure or flow rate indicates that the measuring tube (1; 5) has several or pressure measuring points (A, B, C) in the different line sections. connected. Such measuring devices provide 3. Apparatus according to claim 1 or 2, there »5, however, if they are characterized with different liquid through that the measuring tube (V, S) are driven through, no comparable is designed as part of a main flow pipe. Values. The invention is therefore based on the object to create a measuring device that is as simple as possible, 30 the particular no moving parts within of the flowing liquid and also for different liquid throughputs suitable is. The invention relates to a device for solving this problem, the invention proposes for continuous measurement of the viscosity, the 35 before that the extension of the measuring tube is chosen Consistency or solids concentration is one that is caused by the internal friction of the liquid Liquid, especially a paper pulp, with induced pressure drop between the two one through which the liquid can flow, at least measuring points through the according to the Bernoullischendest along a partial area in the flow direction equation given pressure increase within a tion widening measuring tube, the two pressure * ° certain speed range approximately has measuring points, one of which is compensated in the area. This just gets through the lower and the other in the area of the pipe friction caused differential pressure, the less Pipe cross-section is indirectly a function of viscosity, Such measuring devices are effective in manufacture. Thus, the pressure drop between the of paper is required to obtain a direct measurement for the viscous value via appropriate, in front of both measuring points automatic control devices a sity or consistency or consistency of the measurement constant Weight per unit area of the liquid flowing through the paper-producing encoder. The printing machine To ensure that waste measurement can be conveniently carried out using a commercial measuring device, measuring devices are known that use a conventional differential pressure transmitter or the like Constant speed sensor in the paper stock 5 «> Devices such as those used for moving through flow and those from the retroactive measurement with orifices or venturis who-braking force, the size of which depends on the consistency. is true, the measure for the consistency is derived. It is also known, seen a constant amount, that the measuring tube has several pressure points on paper stcll to flow through a channel and 55 points. This makes it possible to adapt to the the measure of the consistency of the level of the flow- practical design of the measuring section the effective one line of the substance in the channel. Continue to change the length of the encoder so that several measuring devices are used which are possible on a measuring range. Resistance body in the interior of the pipeline. It is also advantageous that the measuring tube as part Moment of force is formed as a result of the flow velocity ^{6o of} a main flow tube. Let this affect, which guide form the measure of the viscosity has the very significant advantage that or gives consistency. for the transducer no branching from the main These known measuring devices have a current pipe is required. Number of disadvantages. First of all, it is necessary, in the drawing, the invention is illustrated by two Moving parts or constrictions in the flow of material ⁶ S exemplary embodiments are illustrated. substance that can lead to constipation. Furthermore development a first embodiment of the measuring tube, cleaning work is very cumbersome because parts F i g. 2 also in a schematic sectional