V cone flowmeter
ZW series of LGVV cone flowmeterWith V cone in the flow field generated by the throttling effect, measured by detecting the differential pressure of upstream and downstream of the flow.Compared with ordinary throttling, it changed the throttling layout, from the center hole throttle annular throttle instead.Practice shows that compared with other flow meter, the flowmeter has high accuracy, good stability for a long time, the installation condition limits small and wear resistance, wide measuring range, small pressure loss and suitable for the advantages of smudges.And V cone itself as the flow field of the rectifier and become a new type has unique properties of excellent flowmeter.
And V cone itself as the flow field of the rectifier and become a new type has unique properties of excellent flowmeter.By V cone sensors and differential pressure transmitter, smart combination flow totalizer.especially v-cone flowmeter, V can accurately measure the width Reynolds number (8 x 103 Re 5 x 107 or less or less) within the scope of all kinds of medium flow.Now a v-shaped cone international standardization, but international flow measurement industry research hot spot.Believe in the near future along with the in-depth research, the improvement of the theory and experimental data, it will be and the standard orifice, standard nozzle, classical venturi meter as a part of the standard throttling device.
Second, the working principle:
ZW series of LGVV cone flowmeter consists of a coaxial installation in the measuring tube tip of the cone and the corresponding pressure, the measuring tube is machined, the differential pressure, pointed at both ends of the cone, the differential pressure of high pressure (positive pressure) is at the upstream fluid contraction front wall static pressure measurement, and low pressure (negative pressure) is taken from the cone pointing downstream face pressure on the center of a cone hole.
* toward the coming flow of the cone, cone and its tail is a sharp acute Angle between the edge of the mating surface makes the fluid into the low pressure area downstream before there is a transition zone of smooth.
Due to fluid near the pipe center axis, not forced to contraction and not a blockage, to change fluid flow direction, but using the new structure of V type cone throttling device realized gradually to the fluid toward the side wall of tube shrinkage, make V cone flowmeter has a series of unique advantages.The low voltage side produce high-frequency low-rising small vortex, the differential pressure and differential pressure transducer is measured is low noise signal, can make the differential pressure transmitter measured high distinguish rate, so that V cone obtained wide range ratio and good repeatability.
Flow sensor produced by the square root of the differential value is proportional to the flow of relationships:
Qv = (c. epsilon)/(1 - beta 4) 0.5 (PI / 4). D2.0.5
Among them: Qv: fluid volume flow
C: the outflow coefficient;
Epsilon: fluid expansion coefficient;
Beta: throttling ratio;
D: throttle diameter;
Δ Ρ: differential pressure value;
Rho 1: working condition of fluid density.
Three, the application, conditions and maintenance:
Mass media: coal gas, natural gas, including humidity below 5%), all kinds of hydrocarbons (including HC gas moisture), all kinds of rare gas (hydrogen, helium, argon, oxygen, nitrogen, etc.), wet chlorine gas, air (including water cut, including SiO2 particles and other air suspension), flue gas, saturated steam (including steam and water two phase flow), superheated steam, water, etc.
Article: from cryogenic to supercritical state, high temperature of 700 ℃, pressure of 40 mpa.
Computing: each cone according to the nature of the fluid, pressure and temperature with special software to calculate.Users can according to your own application conditions (the components of the measured medium, temperature, pressure, pipe diameter, big flow, flow, small flow rate, to allow the pressure loss) choose beta.
D n: cone flowmeter is a maintenance free, do not need regular maintenance and calibration.
Four, the main features:
1, can achieve accuracy can reach 0.5%.
2, range than the typical values of 15: l, at least can range than 10:1, far better than the traditional flowmeter orifice, nozzle, etc.
3, repeatability is better than that of plus or minus 0.1%.
4, when installation required short straight pipe, the upstream requirement 0 to 3 d, the downstream demand 0 to 1 d;Do not need to install flow regulator in upstream of V cone.Greatly save the cost of the fixed condition and installation space.
5, structure design is a fluid sweep type structure of the flow meter, impossible to intercept any entrained in the flow of gas, liquid or solid waste, very suitable for cleaning fluid flow measurement, such as coke oven gas and wet gas, etc.
6. Special special design of the inner cone can be reduced by measuring the pressure (differential pressure) of pulse amplitude of oscillation, thus reducing the noise of the differential pressure signal.Less measurable flow, make the range than widened.
7, have no moving parts, high reliability, and not easily get stuck.
8, when the fluid flows through the inner cone, with special profile will form boundary layer and channel in its surrounding fluid to leave at the end of the cone edge, thus reduced the likelihood of it frayed, thus ensuring the stability of its performance.
9, small pressure loss, energy loss is small, resistance to dirt.Suitable for low static pressure fluid flow measurement using occasions, such as flue gas.
10, easy installation, it is the technical renovation of the ideal flowmeter.
11, free maintenance or maintenance workload is small, which can adjust flow and mixing of fluid.
Five, the technical parameters:
1, the nominal menstruation: 50 mm DN 1800 mm or less or less;
2, nominal pressure: PN 40 mpa or less;
3, the scope of Reynolds number: 8 x 103 Red 107 or less or less;
4, precision grade: 0.5, 1.0;
5, repeatability: 0.1% or less;
6, former straight pipe: 1 ~ 3 d, straight pipe: after 3 ~ 5 d;
7, small pressure loss, only for 1/2 ~ 1/3 of orifice plate;
8 and cone trailing edge vortex is small, stable output pressure side, small fluctuation stability;
9, than a wide range: flow range can reach: 1:15.
The flange type:
1, connection mode: flange (flat welding and butt welding);
2, size: DN15 ~ DN2000;
3, apply pressure method: socket welding, flange, screw thread;
4, pressure: 0 ~ 40 mpa;
5, temperature: - 40 ~ 850 ℃;
6, material: 304 stainless steel, 316 l stainless steel and 20 # carbon steel selection (see table).
7, application: liquid, gas, steam;
8, suitable medium: widely used in municipal, electricity, chemical industry, petroleum chemical industry, metallurgy, food processing and other industries in the flow measurement, suitable for almost all the gas and liquid medium.
Direct welding type:
1, the mode of connection: pipe welded directly to the process;
2, size: DN15 ~ DN2000;
3, apply pressure method: socket welding, flange, screw thread;
4, pressure: 0 ~ 40 mpa;
5, temperature: - 40 ~ 850 ℃;
6, material: 304 stainless steel, 316 l stainless steel and 20 # carbon steel;
7, application: pipeline, pipeline, steam pipe, high pressure pipeline process.
Six, technical advantage and defect:
ZW series of LGVV cone flowmeter due to the unique profile of V cone and its position in the center of the pipe axis make V cone throttling device has convergent divergent side wall of the small shrinkage, low background noise signal, zui wear (since), flow adjustment (since the rectifier), self cleaning, self mixing and other unique features and effectively interact with the center of the high-speed fluid velocity distribution, to enable it to measure the rate of flow of fluid in a unique way, its the technical characteristic is to make it have good effect in general.
Because the V cone structure characteristics, it is also difficult to avoid defects:
1, requirements V cone is better than 0.5%, the accuracy of the requirements for each one meter on the conditions of use of the calibration device as close as possible to real flow calibration, the calibration of its flow coefficient C.
2, V taper has not yet reached the degree of standardization.
3, due to the structure, can't use a V cone of bidirectional flow to meet the demand of the flow measurement.
4, for low Reynolds number (Re < 8000), there is no guarantee that the requirement of linearity and repeatability.
5, because of the need to the front pressure, large volume, high installation fees, limits the V cone market application prospect.
Seven, V cone sensors and differential pressure transmitter of v-cone flowmeter: V
In accordance with user requirements, with V cone sensors and differential pressure transmitter the supply of flow measuring instrument is divided into two categories:
1, V cone sensors provide only the differential signal detection part of the cone and measuring pipe (V), does not provide differential pressure transmitter, part three valve group and flow display, output signal for the differential pressure.By the users themselves.
2, flowmeter consists of V cone sensor and differential pressure transmitter.Have installed points in shape and a size two structures.
Points are installed by an independent V cone of sensor and differential pressure transmitter.V taper between sensor and differential pressure transmitter of pressure pipe connection completed by users themselves.The differential pressure transmitter can form a complete set of supplies.
3, installation is a size product factory has the differential pressure transmitter, three valve group and V cone sensors connected into an organic whole, after users buy a cone shape V, don't need to join again when using pressure tube.For matching the corresponding flow integrator, pressure transmitter and temperature transmitter can form a complete set of supplies.
Eight, functional analysis:
1, throttling features a unique gradually the local contraction of formation fluid, pressure loss is small.
Taper cone throttling components one by one and make the fluid axisymmetric towards the tube wall, gradually shrink, which formed gradually annular contraction.Contract in circulation area of fluid has been gradually accelerated at the same time.Due to the sharp cone axis in the center of the pipe.To make it more efficient effect on the velocity distribution of the central area, and along the cone profile and clearance between pipe wall is without stop.So its role than throttling orifice plate is smaller, the flow capacity than the orifice plate.
Outflow coefficient C of typical values: cone flowmeter is O.80, orifice is O.60.
Due to shrinkage has realized gradually, gradually spread way of side wall throttling, under the same flow rate, the differential value of about half of the orifice differential pressure value.Due to the differential pressure is small, * natural small pressure loss.In the reasonable design, pressure loss of the * at about a quarter of the pressure loss of the orifice meter * (or smaller), so the energy consumption is small.
If according to the known of all kinds of throttle type differential pressure flow meter calculation formula of pressure loss.Found v cone of low pressure loss than the loss of pressure of orifice plate, slightly more than the loss of pressure nozzle.Under the same flow rate, pressure loss of the cone flowmeter * value less than one half of pressure loss of the orifice plate * values.In addition, also should be from the aspects of background noise in order to understand the loss of pressure cone flowmeter: smaller on the downstream side of the cone will form a high speed, high turbulent flow and low pressure area containing small vortex.These small vortex pressure in hole can form the pressure fluctuation signal of high frequency low-rising, this low-rising will form the differential pressure fluctuation signal of the output signal of low noise background noise.Due to the differential output signal in the background noise is small, low differential pressure value can be effectively detected.Take pressure and orifice flowmeter hole forming low frequency high pressure signal, it is not easy to measure.So, relative to the orifice flowmeter, v cone in the design, the designer can choose low differential pressure limit value.Due to the differential value of small, small pressure loss of the * value natural.So compared with the orifice, energy fees will be much smaller.
2, the cone with functions of automatic rectification
V pointed cone of fluid velocity distribution have automatic adjustment function.In an open flow of pipeline, the velocity distribution in a convex shape.Upstream of the pipes will affect the distortion velocity distribution and velocity distribution.V-shaped cone scatter fluid flow in the profile, so that the velocity distribution is more flat.Orifice plate center deflating, suddenly, all of a sudden dispersive throttling, it will only further strengthen the velocity distribution in the convex shape.And deflating cone is a side wall, reducing the divergent type throttle, it can weaken the velocity distribution in the convex shape.In essence, v-shaped pointed cone role as it itself is a flow regulator.It's quite a strong flow adjustment function have been confirmed by the lO for many years a large number of experimental tests, more zui new according to the American petroleum institute, oil measurement standards manual (5.7) API MPMS requirement on the standardization of open test is confirmed.
3, the protection function
Cone profile ensures that no fluid directly suddenly hit its downstream edge.Fluid is along the conical silhouette gradually to the inner wall of pipeline caused by contraction of throttling element.Fluid flow boundary layer automatically protect the key determinants of equivalent diameter ratio B value dimension dv, reduce wear and tear, can ensure the reliability of the meter, so can reduce the maintenance workload and prolong the verification period.Orifice meter fluid is the direct impact of orifice plate, thus the size of the orifice plate precision is not easy to remain stable.
4, noise reduction function
The cone's unique profile has the function of inhibition of differential pressure signal in noise.Unique structure of the cone (in between v pointed cone and its downstream of trailing cone is a small acute Angle) makes the fluid before entering the downstream of the low pressure area has a smooth transition.On the downstream side of the cone to form a high speed, high turbulent flow and low pressure area containing small vortex.On these small vortex pressure in hole can form the pressure fluctuation signal of high frequency low-rising, this low-rising will form the differential pressure fluctuation signal of the output signal of low noise background noise,.And other throttle type differential pressure flow meter (e.g., orifice plate), on the throttling parts, downstream has considerable vortex, so these large vortex in its take high pressure hole can form low frequency amplitude of pressure fluctuation signals, the high amplitude will form the differential pressure fluctuation signal of the output signal of high background noise.By garlic street cone with functions of noise reduction, the differential output signal in the background noise is small, so the cone flowmeter can measure the pressure, uninteresting facts can effectively measure the flow, so that the range than widened.Due to the differential output signal in the background noise is small, so the design of conical flow time, allow choose low differential pressure limit value.Due to the differential pressure is small, small pressure loss of the natural, so energy consumption is small.
5, self cleaning function
No dead Angle in the fluid flow path.As long as the continuous use it, in its internal there can be no fluid/gas/solid particles.Fluid in the entrained droplets, bubbles and solid particles are completely automatic cleaning to the downstream piping.The orifice meter in orifice plate front is prone to a corner and deposition.
6, the mixed function
The cone has the function of mixer.When the fluid flows through the cone of heterogeneous heterogeneous flow experience mixed into homogeneous fluid by itself, and by V cone efficient flow measurement.And orifice through circulation area change, just put the fluid acceleration, no mixing action.Due to the unique profile of cone and its position in the center of the pipe axis make v inner cone throttling device has convergent divergent side wall of the small shrinkage, low background noise signal, zui wear (since), flow adjustment (since the rectifier), self cleaning, self mixing and other unique features and effectively interact with the center of the high-speed fluid velocity distribution.This can make it in a unique way to measure the rate of flow of fluid, with excellent technical characteristics.
Ten, installation site:
Even in comparison also can work normally under harsh conditions, but for the sake of the use of safe and stable for a long time, during the installation, please pay attention to the points:
1, the installation place shock and vibration
Is the factory design of the can absorb a certain amount of shock and vibration.But should also try to install where no vibration or vibration.
2, installation site ambient temperature conditions
Please try to avoid the flow meter installed in the environment temperature change is big, if the installation location is directly thermal radiation or waste their exposure to day rain, waterproof, heat radiation and ventilation measures should be taken.
3, installation site ambient air conditions
Should be avoided in the corrosive environment, if used in the corrosion environment, should have good ventilation and avoid corrosive gas or liquid into the instrument.
Eleven, installation requirements:
Guide to transducer pressure of pipe used for the transmission process, if the pressure tube of the gas in the liquid or the gas pipe in the residue, cannot correct for pressure transmission, can produce error, therefore, equipped with guide of pressure pipe should be pay attention to:
Guide the installation of pressure pipe guide valve Angle:
Process fluid is a gas and steam, and guide valve installation position should be above the process piping, process fluid is a liquid lead valve installation position should be at the bottom of the process piping.
1, the process fluid is a gas, transmitter position should be higher than the pressure valve, liquid and steam process of a fluid, transmitter position should be lower than pressure valve.
2, high and low voltage side of the guide tube does not produce temperature difference.
3, application in measuring the steam condenser.
Nine, use notice:
1, and the postal inspection specifications confirmation:
Play is put on the market after a full inspection, when the user types and specifications, please after receipt of the goods in a timely manner to confirm, and check whether there is damage appearance, types and specifications of engraving on the nameplate on the outside of the flowmeter, and shall confirm the receipt of the goods and packing box parts listed on the packing list whether is complete.
2, transportation and storage conditions:
On his way to prevent the transport and handling damage instrument, in the work site prior to installation, please keep this product appearance because the packing condition.
When stored in a need for a long time, please pay attention to the points:
A, in not affected by shock and vibration.
B, avoid exposure to the wind rain, wet storage environment must be put in room temperature often (25 ℃;Around 65% RH)
C, try to keep in this product factory packing condition for storage.
D, used a product to save, please make sure the residue within the instrument clean.
Eleven, selection of coding:
VIn the cone type flowmeter (wei measurement and control)
High temperature medium
Compensation in the form of
Without pressure and temperature compensation
With compensation output pressure and temperature
The connection form
Threaded connections (applicable to small diameter)
12 order, design notes:
When you place an order, please provide the following conditions in order to help the correct choice of the specifications of the flowmeter and coefficient.
1, pipe size: diameter x wall thickness (mm);
2, measuring medium name: medium density (kg/m3);
3, set the flow range: meter range of upper limit and lower limit (kg/h or m3 / h);
5, work pressure (Mpa);
6, work temperature: (° C);
7, such as wei in my company, please provide together: intelligent flow totalizer.especially pressure range, or pressure transmitter type, range;Temperature range, or models, range temperature transmitter.
After-sales service commitment:
1, from the date of signing of the contract, I in the way provided for products of the company offers free maintenance and maintenance service, commitment to lifelong maintenance service;
2, jiangsu wei measurement and control instrument co., LTD. Sales manager will be in regular contact with customers, understand the usage of products, and solve the problems of the customers to use in the process of produce, free of charge to provide technical support;
3 the man-made damage is found, the warranty period, our company is responsible for the maintenance, and the resulting maintenance fee;
4, product quality problems or are not satisfied with product, the user can choose unconditional return, wei tt&c don't charge any fees, appear quality problem, bear the freight back and forth.