CN2663939Y

CN2663939Y - Detection device of Coriolis mass flowmeter

Info

Publication number: CN2663939Y
Application number: CN 200320115916
Authority: CN
Inventors: 叶林; 张�杰
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2003-11-18
Filing date: 2003-11-18
Publication date: 2004-12-15
Anticipated expiration: 2013-11-18

Abstract

The utility model relates to a detection device of a Coriolis mass flowmeter, which belongs to a measuring device of flux and mass flow. The utility model is used for increasing the measuring sensitivity and lowering the conformance requirement of a detecting tube. An electromagnetic vibrator is arranged in middle position of the detecting tube of the utility model. A vibration transducer is installed on the symmetrical side of the detecting tube. The straight pipe section of the detecting tube or the detecting tube and the connecting section of a process pipe are composed of corrugated flexible metal tubes. Resilient supporting devices are installed on both symmetrical sides of the detecting tube. The utility model greatly enhances the measuring sensitivity, and lowers the requirement for the compatibility of the detecting tube. The difficulty of machining is decreased, the production cost is cut down, the maintainability is enhanced, and the power consumption of the system is decreased.

Description

The pick-up unit of coriolis mass flowmeters

Technical field

The utility model belongs to the measurement mechanism of flow, mass flow.

Background technology

Existing Coriolis (Coriolis) mass flowmeter all has the detector tube of one section single tube or parallel double tube, electromagnetic exciter is equipped with in the detector tube middle part, the symmetrical side of detector tube is equipped with vibration transducer, during work, detector tube is with certain mode vibration, when fluid flows through this detector tube, can cause the oscillating movement of detector tube both sides that minute differences was arranged on time phase, this phase time extent is directly proportional with the size of mass rate in the detector tube, and the size that detects this time phase differential has just realized the direct measurement to mass rate.Detector tube has U-shaped, Ω shape, and straight tube shape, annular etc.

In the prior art, detector tube is rigid pipe and is rigidly connected with being connected also of process pipe; Patent " Coriolis (Coriolis) flowmeter that the ripple flow duct is arranged " (publication number CN1258348A, application number 98805655.0) is arranged in addition, and the part pipeline section of detector tube is made up of corrugated tube.Though this design makes moderate progress than original full rigid pipe sensitivity in sensitivity, but still weak point is arranged: corrugated tube unprotect shell, thereby its voltage endurance capability is limited, also subjects to damage, causes detector tube leakage accident; The raising of sensitivity is limited; Lack elastic bearing mechanism in the detector tube structure, the change adjustment of its dynamics is difficulty relatively.

Summary of the invention

The utility model proposes the pick-up unit of a kind of Coriolis (Coriolis) mass flowmeter, adopt detector tube to comprise the design that links to each other by corrugated flexible metal tube that is connected of corrugated flexible metal tube (the following metal hose that all is called for short) or detector tube and process pipe, make flowmeter to the sensitivity of mass flow measurement than being rigidly connected and having the flowmeter of the detector tube of corrugated tube to be greatly improved, and conforming requirement is concentrated on the metal hose, and the coherence request of detector tube itself is greatly reduced, thereby make processing more easy.

The pick-up unit of a kind of Coriolis of the present utility model (Coriolis) mass flowmeter comprises one or two identical detector tubes, and electromagnetic exciter is equipped with in the detector tube middle part, and the symmetrical side of detector tube is equipped with vibration transducer, and its characteristics are:

(1) described detector tube straight length part is made up of ripple all-metal flexible pipe, and described corrugated flexible metal tube is the flexible hose that metal bellow is with steel wire or steel band braiding net outward;

(2) resilient supporting unit is equipped with in the symmetrical both sides of described detector tube.

The pick-up unit of described Coriolis (Coriolis) mass flowmeter, it is further characterized in that the coupling part of stating detector tube and process pipe is made up of corrugated flexible metal tube.

The pick-up unit of described Coriolis (Coriolis) mass flowmeter, described resilient supporting unit can comprise flexible member and connector, flexible member curves the closed circular arc, closed circular arc upper limb is with last connector or directly be connected with pedestal, closed circular arc lower edge is connected with lower connector, and lower connector is used for the detector tube that is supported is fixed.

The utility model detector tube planform is still the same with prior art, adopts single or double joint pipe, and shape can be U-shaped, Ω shape, straight tube shape, semicircle.But the part pipeline section of detector tube adopts metal hose; Or the rigidity detector tube linked to each other with being connected by metal hose of process pipe.Type of attachment is welding, or flange, or certain rapid-acting coupling, and this is mainly by the pipeline drift diameter size, and factors such as actuating medium and requirement of withstand voltage are determined.

It must be emphasized that metal hose and plain metal corrugated tube have essential distinction, are mainly:

(1) though both all have ripple, the shape of metal hose, moulding process is different fully with common corrugated tube;

(2) metal hose is flexible, and common corrugated flexible hose can have the bigger anti-rigidity that radially bends.The metal hose of identical physical dimension (being latus rectum, effective length) is different fully with the characteristic of common corrugated tube, and when discussing with the semi-girder model, its free end is diverse on the mechanical characteristic in the radial vibration.

(3) the metal hose structure is different with common corrugated tube, and there are one or more layers steel wire or steel band net in the former outside, makes metal hose can bear higher pressure medium, also can protect inner bellows body and avoid mechanical damage, can also improve its abrasion resistance properties.And common corrugated tube is without any outer protection structure.

Therefore, adopting the technology and the common corrugated tube technology of the prior art of metal hose in the utility model is diverse design concept and technical method.After detector tube includes metal hose in the utility model, show the characteristics that rigidity reduces significantly on the vibration mechanics characteristic of detector tube.For making detector tube can continue to utilize Ke Shi to detect the mechanics principle of mass rate with certain mode vibration, the utility model also comprises another requisite design, the symmetrical both sides or the central spot of Here it is this detector tube, adopt resilient supporting unit, so that the vibration dynamics characteristic of detector tube satisfies the requirement that Coriolis mass flow detects principle.

Characteristics of the present utility model are presented as:

(1) can increase substantially measurement sensitivity, make the measurement of flow of low-density medium become possibility.

(2) greatly reduce the conforming requirement of detector tube, make difficulty of processing, production cost descends.

(3) vibrational excitation power descends, and system power dissipation is reduced, and also can improve the instrument explosion-proof performance.

(4) elastic bearing can be selected permanent bullet alloy flexible member for use, thereby can guarantee that detector tube vibration dynamics characteristic is stable in a wider temperature range.

(5) make the elastic bearing characteristic to adjust easily by specially designed resiliency supported adjusting mechanism, thereby vibration frequency point can be changed, to be operated on the optimum frequency point.Simultaneously, except that closed loop self-sustained oscillation mode, it swashs working method also can to select open loop for use.

(6) metal hose two ends adapted has all more convenient jointing of dress/unload, thereby when detector tube or flexible pipe itself have fault to change, can be dismantled easily and install, and need not dismantle whole instrument piping system, and maintainability is greatly improved.

Description of drawings

Fig. 1 is a vertical view on a kind of embodiment of the present utility model;

Fig. 2 is the front elevation of Fig. 1;

Fig. 3 is the corrugated flexible metal tube structural representation that the utility model adopted;

Fig. 4 is the A-A diagrammatic cross-section of Fig. 2, reflects a kind of flexibly mounted concrete structure.

Embodiment

Be that example illustrates a kind of embodiment of the present utility model with a kind of detector tube of double-U-shaped tubular type now in conjunction with Fig. 1, Fig. 2.01 is the arc section of rigidity detector tube among Fig. 1,04,11st, and the straight length of rigidity detector tube, 18 is side pipe sections of following U type pipe among Fig. 2, the symmetrical side of last U type pipe fails to draw.By 01,04, the 11 rigidity detector tubes of forming link to each other with

process pipe

06,09 by

metal hose

05,10, and

metal hose

05,10 also becomes effective part of detector tube, and process pipe is installed on the pedestal by holder 07,08.03,12nd, cooperate

flexible pipe

05,10 plastic deformation and the resilient supporting unit that designs.The 14th, drive the electromagnetic exciter that detector tube vibrates, 02,13rd, the oscillating movement sensor is to obtain vibration signal.Among Fig. 2, the straight length 18 of U type pipe, metal hose 17, process pipe 16 pass through on holder 15 installations and the pedestal under constituting, and by resilient supporting unit 19 supportings, the symmetrical side of following U type pipe fails to draw.Like this, when 14 produced exciting forces,

detector tube

11,18 was made tuning-fork type and is vibrated two about, and 02,13 vibration signal that obtains send Circuits System to handle, and it is poor to try to achieve phase time, again through scale transformation, just can obtain the measurement result of mass rate.

In the design of this instrument system, except that metal hose and elastic bearing, all the other all are existing about being parts that the public was familiar with in the Coriolis flowmeter known technology, thus below only metal hose and elastic bearing are described specifically.

Figure 3 shows that the structural representation of corrugated flexible metal tube.Corrugated flexible metal tube is on bellows body 20, establishment one deck or which floor steel wire or steel band net 21, and its two ends are equipped with the flexible hose of forming with piping or the joining various terminal 22 of equipment again.

Bellows body is a kind of thin-walled stainless steel tube that has spirality or belt ripple diametrically, in order to through-flow medium.Because it radially has ripple, so it has good flexural property.

Though this bellows body its radially bearing capacity is strong, it just can produce elongation under responsive to axial force, so limited the load-bearing capacity of corrugated flexible metal tube greatly.For this reason, one or more layers stainless steel wire of braiding or steel band net on bellows body, main in order to bear the axial force that pressure medium causes, the load-bearing capacity of corrugated flexible metal tube is greatly improved.Simultaneously, the braided steel wire net can also be subjected to mechanical injuries and improve crocking resistance by protective corrugated tube.

Joint and bellows body, wire sets weld together, and are used for linking with piping or equipment.Joint is divided into screw-type, flange plate type and rapid-acting coupling formula three classes substantially.The combination in twos of these joints constitutes the corrugated flexible metal tube of different connection forms.Joint generally adopts stainless steel to make.But also can adopt simple steel flange and copper rapid-acting coupling.Obviously, the one end is connected process pipe, other end joint detection pipe, then it can have minimum bendind rigidity to produce along Y direction deflection deformation up and down, therefore, when coriolis force acts on the detector tube, can cause bigger phase time poor, thereby the flowmeter that makes this conceptual design have very high sensitivity to the detection of mass rate.

The latus rectum of metal hose is identical with the detector tube latus rectum, effective length then must be determined a reasonable value in conjunction with factors such as vibration dynamics characteristic, flexibly mounted design and alternation fatigue lifetives, so that under the maximum cyclic deformation condition, the stress of metal hose satisfies the requirement of alternation fatigue safety energy; Cooperate the elastic bearing adopted, make whole detector tube total system dynamics (as resonance frequency etc.) meet the requirement that mass rate detects.

Figure 4 shows that the diagrammatic cross-section of A-A orientation among Fig. 2, reflect flexibly mounted a kind of specific design.The elastic support structure of two pipes is identical up and down, and difference only is the initial tension of the flexible member of pipe, and the initial pressurized of flexible member of following pipe.Existing above tubular elastic supporting specifically describes for example.

Bolt 23,25 is connected connector 26 with flexible member sheet 28, detector tube 27 and linking to each other of connector 26 can be welding manners or connect by high strength bonding is gluing.The radius-of-curvature of connector circular arc portion varies in size and can play the effect of fine setting elastic property.Coupling bolt 24 takes advantage of pedestal 29 to be connected flexible member sheet 28 with last, flexible member sheet 28 can select for use the permanent alloy that plays to make, its two ends so that flexible member sheet 28 can be strained or loosen, reach the purpose of adjustment forming the strip mounting holes with 24 supporting screw hole places.

Claims

1, a kind of pick-up unit of coriolis mass flowmeters comprises one or two identical detector tubes, and electromagnetic exciter is equipped with in the detector tube middle part, and the symmetrical side of detector tube is equipped with vibration transducer, it is characterized in that:

(1) state detector tube straight length part and be made up of corrugated flexible metal tube, described corrugated flexible metal tube is

Metal bellow is with the flexible hose of steel wire or steel band braiding net outward;

(2) resilient supporting unit is equipped with in the symmetrical both sides of stating detector tube.

2, the pick-up unit of coriolis mass flowmeters as claimed in claim 1 is characterized in that the coupling part of described detector tube and process pipe is made up of corrugated flexible metal tube.

3, the pick-up unit of coriolis mass flowmeters as claimed in claim 1 or 2, it is characterized in that described resilient supporting unit comprises flexible member and connector, flexible member curves the closed circular arc, closed circular arc upper limb is with last connector or directly be connected with pedestal, closed circular arc lower edge is connected with lower connector, and lower connector is used for the detector tube that is supported is fixed.