工業(yè)流量計：工作原理與類型介紹（中英文）
流量計是測量流體流量的工具。它們是一種流量測量裝置，能夠測量氣體或液體的線性、非線性、質(zhì)量或體積流量，也稱為流量計或流量測量裝置。精確測量流體流量對于工業(yè)過程的質(zhì)量控制至關(guān)重要。
Flow meters are tools that measure the flow rate of a fluid. They are flow measuring devices able to measure the linear, non-linear, mass or volumetric flow rate of a gas or a liquid and are also named Flow Gauges or flow measurement devices. Precise flow measurements of fluids are required for the efficient quality and control of industrial processes.
流量計的類型：
Types of Flow Meters:
一般來說，流量計分為兩種類型：
Generally, two types of flow meters are known:
容積流量計
Volumetric Flow Meter
之所以稱為容積流量計，是因為它們測量的是特定時間段內(nèi)流經(jīng)特定位置的流體體積。
這些工具可以提供氣體或液體體積流量的瞬時模擬、數(shù)字或脈沖輸出。
下面將介紹不同類型的流量計。
They are called volumetric flow meters because they measure the volume of fluid passing through a particular location over a specified period of time.
These tools provide us with an instantaneous analog, digital or pulse output of the volume flow rate of the gas or liquid.
In the following, different types of flow meters will be mentioned.
質(zhì)量流量計
Mass Flow Meter
質(zhì)量流量計測量單位時間內(nèi)流經(jīng)管道的流體質(zhì)量流量。
Mass flow meters measure the fluid mass flow rate that travels through a tube per unit of time.
容積式流量計的類型：
Types of Volumetric Flow Meters:
? 差壓式流量計
? 變面積式流量計（轉(zhuǎn)子流量計）
? 電磁流量計
? 超聲波流量計
? 渦輪流量計
? 渦街流量計
? 容積式流量計
? Differential Head type
? Variable Area type (Rota meters)
? Magnetic flow meters
? Ultrasonic flow meters
? Turbine flow meters
? Vortex flow meters
? Positive Displacement Meters
質(zhì)量流量計的類型
Types of Mass Flow Meters
? 科里奧利質(zhì)量流量計
? 熱式質(zhì)量流量計
接下來將介紹工業(yè)界常用的幾種不同類型的流量計。
? Coriolis Mass flow meter
? Thermal Mass flow meters
What comes next is the explanation of different type of flow meters which are popular in the industries.
什么是差壓式流量計
What is a Differential Head Flow Meter
在受限流體流動中，流體在節(jié)流口上游和下游之間存在壓差，該壓差與流體速度的平方成正比。
Q α √ ΔP
（Q = 體積流量，ΔP = 取壓口之間的壓差）
差壓式流量計本身有三種不同的類型。
There is a pressure difference between the upstream & downstream sides of a restriction in a confined fluid stream, which is related to the square of fluid velocity.
Q α √ ΔP
(Q = Volume flow rate and ΔP = Differential pressure between taps)
A Differential Head Flow Meter itself has three distinct types.
孔板
Orifice plates
孔板有兩種類型：
? 同心孔板：這是最常用的孔板。
? 扇形孔板和偏心孔板：用于含有懸浮固體的流體。
There are two different types of Orifice plates
? Concentric orifice plates: they are the most commonly used Orifice plates.
? Segmental & Eccentric orifice plates: they are used for fluids containing suspended solids.
文丘里流量計
Venturi Meters
文丘里管通過壓縮流體并測量壓降來測量流量。在文丘里流量計的上游錐體中，流速較高，壓力較低。
上游錐體的壓降用于估算流經(jīng)該裝置的流量。
A venturi tube measures flow rates by compressing fluids and measuring the differential pressure drop. In the upstream cone of the Venturi meter, the velocity is higher, and the pressure is lower.
Pressure drop in the upstream cone is used to estimate the rate of flow through the device.
Annubar 流量計
Annubar
它是一種用于測量管道中流體（液體、蒸汽或氣體）流量的儀器。流量的測量是通過產(chǎn)生壓差來實現(xiàn)的。
根據(jù)伯努利定理，該壓差與管道中流體速度的平方成正比。
這些流量計測量壓差，然后使用另一種儀器將壓差轉(zhuǎn)換為流量。
It is an instrument used for measuring the fluid flow (liquid, vapor, or gas) in a pipeline. The flow is measured by creating a differential pressure.
As per Bernoulli’s theorem, this differential pressure is proportional to the square of the fluid velocity in the pipeline.
These flow meters measure the differential pressure which is then converted to flow rate using another instrument.
什么是變面積流量計（轉(zhuǎn)子流量計）？
What is a Variable Area Flow Meter (Rota meters)?
變面積流量計或轉(zhuǎn)子流量計是應(yīng)用最廣泛的常用流量計類型之一。
它們由一根垂直的玻璃或塑料管組成。管子的尺寸從上到下逐漸變化，因此被稱為變面積流量計。管內(nèi)有一個可自由移動的計量浮子。
Variable area flow meters or Rota meters are one of the widely used common flow meter types.
They include a vertical glass or plastic tube. The dimension of the tubes varies from top to bottom; that’s why they're called variable area flow meters. Within the tubes, there is a free-moving metering float.
什么是磁流量計？
What is a Magnetic Flow Meter?
根據(jù)法拉第電磁感應(yīng)定律，導(dǎo)電液體流經(jīng)磁場時，會在安裝在流量管壁上的電極上產(chǎn)生電壓信號。
流體流動速度越快，產(chǎn)生的電壓就越大。產(chǎn)生的電壓與液體的流量成正比。
磁流量計正是利用了法拉第電磁感應(yīng)定律。為了區(qū)分液體的流量，電壓信號會由電子變送器進(jìn)行處理。
According to Faraday's law of electromagnetic induction, a conductive liquid flow through a magnetic field makes electrodes that are installed on the walls of flow tubes to detect the voltage signal.
The quicker the motion of the fluid, the more the generation of the voltage is. The generated voltage will be proportional to the movement of the liquid that is flowing.
Faraday's law is applied in magnetic flow meters. To distinguish the flow of the liquid, the voltage signal will be processed by the electronic transmitter.
磁流量計的技術(shù)原理是產(chǎn)生與流量呈線性關(guān)系的信號。這是它與其他流量計技術(shù)的區(qū)別之一。
這使得磁流量計的量程比可以達(dá)到 20:1 甚至更高，而不會影響精度。這類流量計非常受歡迎。
The technology of magnetic flow meters generates signals that are linear with the flow. This is one of the differences between this type of technology and other flow meter technologies.
This allows the turndown of the magnetic flow meters to reach 20: 1 or even better, without compromising accuracy. These flow meters are very popular.
什么是超聲波流量計？
What is an Ultrasonic Flow Meter?
其結(jié)構(gòu)和功能如下：一對（或幾對）換能器，每個換能器都帶有發(fā)射器和接收器，分別安裝在管道壁上，一組位于上游，另一組位于下游。
聲波從上游換能器傳播到下游換能器所需的時間 (td) 比從下游換能器傳播到上游所需的時間 (tu) 短。
時間差越大，流速越高。
Their structure and function are as follows: A pair (or pairs) of transducers, each of which has its transmitter and receiver, are placed on the pipe wall, one (set) on the upstream and the other (set) on the downstream.
The time for acoustic waves to travel from the upstream transducer to the downstream transducer (td) is shorter than the time it requires for the same waves to travel from the downstream to the upstream (tu).
The more the difference, the higher the flow speed.
這些傳感器只能測量潔凈的液體和氣體。這些流量計廣泛應(yīng)用于以下行業(yè)：
? 石油和天然氣
? 水和廢水處理
? 電力
? 化工
? 食品和飲料
? 制藥
? 金屬和采礦
? 紙漿和造紙
Only clean liquids and gasses can be measured by these sensors. These flow meters are applied in various industries including:
? Oil and gas
? Water and wastewater
? Power
? Chemical
? Food and beverage
? Pharmaceutical
? Metals and mining
? Pulp and paper
什么是渦輪流量計？
What is a Turbine Flow Meter?
渦輪流量計利用流體的機械能驅(qū)動流體中的“轉(zhuǎn)子”（轉(zhuǎn)子）旋轉(zhuǎn)。
轉(zhuǎn)子上裝有傾斜的葉片，可以將流體的能量轉(zhuǎn)化為旋轉(zhuǎn)動能。轉(zhuǎn)子軸繞軸承旋轉(zhuǎn)。
流體流速越快，轉(zhuǎn)子的轉(zhuǎn)速也相應(yīng)加快。
目前，渦輪流量計占全球流量計銷售額的7%。
In order to rotate a “pinwheel” (rotor) in the flow stream, the turbine flow meters utilize the mechanical energy of the fluid.
The rotor has angled blades on it to transform energy from the flow steam into rotational energy. The rotor shaft rotates around bearings.
The faster the motion of the fluid, proportionally faster the rotor’s rotation.
Today, Turbine flow meters account for 7% of global sales of flow meters.
軸的旋轉(zhuǎn)可以通過傳感葉片的運動或機械方式來檢測。每個葉片或嵌入的金屬部件都會產(chǎn)生一個脈沖，這使得通過磁性方式檢測葉片的運動成為可能。
如果使用浸沒式傳感器，可能會受到材料結(jié)構(gòu)的限制。因此，渦輪流量計傳感器通常安裝在流體外部。流體流動速度越快，產(chǎn)生的脈沖數(shù)量就越多。
為了確定流體流量，變送器會對脈沖信號進(jìn)行處理。傳感系統(tǒng)和變送器可以檢測正向和反向的流動。
The shaft’s rotation can be detected by sensing the movement of the blades or in a mechanical way. Each blade or embedded piece of metal produces a pulse and this makes magnetically detection of blade movement possible.
If wetted sensors are used, material of construction constraints may occur. That's why turbine flow meter sensors are usually installed external to the flowing stream. Faster the movement of the fluid, the more the number of generated pulses.
In order to determine the fluid flow, the transmitter processes the pulse signal. Sensing systems and transmitters are present to detect flow in forward and reverse flow directions.
什么是渦街流量計？
What is a Vortex Flow Meter?
在這種類型的流量計中，流體流動時，渦流會從閥體交替的側(cè)面脫落，脫落頻率與流體速度成正比。
渦流的識別是通過渦流中的壓力變化來實現(xiàn)的。渦流的發(fā)展速率與流量成正比。
In this type of flow meters, Along with the fluid flow vortices are shed from the body’s alternating sides and this shedding frequency is exactly proportional to fluid velocity.
Distinguishing the vortices will be done through pressure changes in the vortex stream. The rate of vortices’ development is exactly proportional to the rate of flow.
什么是容積式流量計？
What is a Positive Displacement Flow Meter?
容積式流量計是唯一一種直接測量流經(jīng)流量計的流體體積的流量測量技術(shù)。
容積式流量計的工作原理是頻繁地截取流體并測量其流量?？梢詫⑦@個過程想象成頻繁地用液體裝滿一個桶，然后再將桶里的液體傾倒到下游。
The only flow measurement technology which straightly measures the volume of the fluid passing through the flow meter is Positive displacement flow meter technology.
Positive displacement flow meters do this via frequently entrapping fluid and measuring its flow. We can think of this process as frequently filling a bucket with fluid before dumping the contents downstream.
水桶裝滿和排空的次數(shù)顯示了流經(jīng)流量計的流量。
容積式流量計有多種幾何形狀可供選擇。
The number of times the bucket gets full and empty shows the flow through the flow meter.
Many positive displacement flow meter geometries are available.
什么是科里奧利質(zhì)量流量計？
What is a Coriolis Mass Flow Meter?
? 當(dāng)運動的物體受到垂直于其運動方向的振蕩時，會產(chǎn)生科里奧利力，該力與質(zhì)量流量成正比。
? 在一個周期的第一個主周期內(nèi)，當(dāng)管道向上運動時，流入流量計的流體會抵抗向上運動的阻力，即向下推動管道。
? 另一方面，流出流量計的流體會抵抗向上運動的阻力，即向上推動管道。這種運動會導(dǎo)致管道發(fā)生扭轉(zhuǎn)。
? 這種扭轉(zhuǎn)運動由傳感器感應(yīng)，并直接與質(zhì)量流量相關(guān)聯(lián)。
? When a moving mass is subjected to an oscillation perpendicular to its direction of movement, Coriolis forces arise relying on the mass flow.
? When the tube is moving upward throughout the first primary of a cycle, the fluid flowing into the meter resists being forced up with the aid of pushing down on the tube.
? On the other side, the fluid flowing out of the meter resists having its vertical motion reduced with the aid of pushing up on the tube. This motion makes the tube twist.
? This twisting motion is sensed with the aid of a pick-up and is immediately associated with the mass flow rate
什么是熱式質(zhì)量流量計？
What is a Thermal Mass Flow Meter?
熱式流量計最常用于測量潔凈氣體的質(zhì)量流量，例如空氣、氮氣、氫氣、氦氣、氨氣、氬氣和其他工業(yè)氣體。
其工作原理如下：
? 通過監(jiān)測氣流流經(jīng)加熱式傳感器時的冷卻效應(yīng)來工作。
? 氣流流經(jīng)兩個 PT100 型 RTD 傳感器。
? 溫度傳感器監(jiān)測實際氣體過程溫度，而自加熱式傳感器則通過改變流經(jīng)它的電流來保持恒定的溫差。
? 流經(jīng)加熱式傳感器的質(zhì)量流量越大，維持恒定溫差所需的電流就越大。
? 因此，估算的加熱器電流即可用于估算氣體質(zhì)量流量。
Thermal flow meters are most routinely utilized to measure the mass flow of clean gasses, such as air, nitrogen, hydrogen, helium, ammonia, argon, and other industrial gasses.
Their function is as follows:
? They work by monitoring the cooling effect of a gas stream as it travels over a heated transducer.
? Gas flow passes over two PT100, RTD transducers.
? The temperature transducer monitors the actual gas process temperature, while the self-heated transducer is kept at a constant differential temperature by changing the current through it.
? The more the mass flow passes over the heated transducer, the more current is needed to maintain a constant differential temperature.
? The estimated heater current is, hence, an estimation of the gas mass flow rate.
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