工业流量计：工作原理与类型介绍（中英文）

流量计是测量流体流量的工具。它们是一种流量测量装置，能够测量气体或液体的线性、非线性、质量或体积流量，也称为流量计或流量测量装置。精确测量流体流量对于工业过程的质量控制至关重要。

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.

流量计的类型：

Types of Flow Meters:

一般来说，流量计分为两种类型：

Generally, two types of flow meters are known:

容积流量计

Volumetric Flow Meter 

之所以称为容积流量计，是因为它们测量的是特定时间段内流经特定位置的流体体积。

这些工具可以提供气体或液体体积流量的瞬时模拟、数字或脉冲输出。

下面将介绍不同类型的流量计。

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. 

质量流量计

Mass Flow Meter 

质量流量计测量单位时间内流经管道的流体质量流量。

Mass flow meters measure the fluid mass flow rate that travels through a tube per unit of time.

容积式流量计的类型：

Types of Volumetric Flow Meters:

• 差压式流量计

• 变面积式流量计（转子流量计）

• 电磁流量计

• 超声波流量计

• 涡轮流量计

• 涡街流量计

• 容积式流量计

• Differential Head type 

• Variable Area type (Rota meters) 

• Magnetic flow meters 

• Ultrasonic flow meters 

• Turbine flow meters 

• Vortex flow meters 

• Positive Displacement Meters

质量流量计的类型

Types of Mass Flow Meters 

• 科里奥利质量流量计

• 热式质量流量计

接下来将介绍工业界常用的几种不同类型的流量计。

• 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.

什么是差压式流量计

What is a Differential Head Flow Meter

在受限流体流动中，流体在节流口上游和下游之间存在压差，该压差与流体速度的平方成正比。

Q α √ ΔP

（Q = 体积流量，ΔP = 取压口之间的压差）

差压式流量计本身有三种不同的类型。

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

孔板有两种类型：

• 同心孔板：这是最常用的孔板。

• 扇形孔板和偏心孔板：用于含有悬浮固体的流体。

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. 

文丘里流量计

Venturi Meters 

文丘里管通过压缩流体并测量压降来测量流量。在文丘里流量计的上游锥体中，流速较高，压力较低。

上游锥体的压降用于估算流经该装置的流量。

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 流量计

Annubar 

它是一种用于测量管道中流体（液体、蒸汽或气体）流量的仪器。流量的测量是通过产生压差来实现的。

根据伯努利定理，该压差与管道中流体速度的平方成正比。

这些流量计测量压差，然后使用另一种仪器将压差转换为流量。

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.

什么是变面积流量计（转子流量计）？

What is a Variable Area Flow Meter (Rota meters)? 

变面积流量计或转子流量计是应用最广泛的常用流量计类型之一。

它们由一根垂直的玻璃或塑料管组成。管子的尺寸从上到下逐渐变化，因此被称为变面积流量计。管内有一个可自由移动的计量浮子。

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.

什么是磁流量计？

What is a Magnetic Flow Meter? 

根据法拉第电磁感应定律，导电液体流经磁场时，会在安装在流量管壁上的电极上产生电压信号。

流体流动速度越快，产生的电压就越大。产生的电压与液体的流量成正比。

磁流量计正是利用了法拉第电磁感应定律。为了区分液体的流量，电压信号会由电子变送器进行处理。

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. 

磁流量计的技术原理是产生与流量呈线性关系的信号。这是它与其他流量计技术的区别之一。

这使得磁流量计的量程比可以达到 20:1 甚至更高，而不会影响精度。这类流量计非常受欢迎。

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.

什么是超声波流量计？

What is an Ultrasonic Flow Meter? 

其结构和功能如下：一对（或几对）换能器，每个换能器都带有发射器和接收器，分别安装在管道壁上，一组位于上游，另一组位于下游。

声波从上游换能器传播到下游换能器所需的时间 (td) 比从下游换能器传播到上游所需的时间 (tu) 短。

时间差越大，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.

这些传感器只能测量洁净的液体和气体。这些流量计广泛应用于以下行业：

• 石油和天然气

• 水和废水处理

• 电力

• 化工

• 食品和饮料

• 制药

• 金属和采矿

• 纸浆和造纸

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

什么是涡轮流量计？

What is a Turbine Flow Meter? 

涡轮流量计利用流体的机械能驱动流体中的“转子”（转子）旋转。

转子上装有倾斜的叶片，可以将流体的能量转化为旋转动能。转子轴绕轴承旋转。

流体流速越快，转子的转速也相应加快。

目前，涡轮流量计占全球流量计销售额的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. 

轴的旋转可以通过传感叶片的运动或机械方式来检测。每个叶片或嵌入的金属部件都会产生一个脉冲，这使得通过磁性方式检测叶片的运动成为可能。

如果使用浸没式传感器，可能会受到材料结构的限制。因此，涡轮流量计传感器通常安装在流体外部。流体流动速度越快，产生的脉冲数量就越多。

为了确定流体流量，变送器会对脉冲信号进行处理。传感系统和变送器可以检测正向和反向的流动。

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.

什么是涡街流量计？

What is a Vortex Flow Meter? 

在这种类型的流量计中，流体流动时，涡流会从阀体交替的侧面脱落，脱落频率与流体速度成正比。

涡流的识别是通过涡流中的压力变化来实现的。涡流的发展速率与流量成正比。

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.

什么是容积式流量计？

What is a Positive Displacement Flow Meter? 

容积式流量计是唯一一种直接测量流经流量计的流体体积的流量测量技术。

容积式流量计的工作原理是频繁地截取流体并测量其流量。可以将这个过程想象成频繁地用液体装满一个桶，然后再将桶里的液体倾倒到下游。

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. 

水桶装满和排空的次数显示了流经流量计的流量。

容积式流量计有多种几何形状可供选择。

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.

什么是科里奥利质量流量计？

What is a Coriolis Mass Flow Meter? 

• 当运动的物体受到垂直于其运动方向的振荡时，会产生科里奥利力，该力与质量流量成正比。

• 在一个周期的第一个主周期内，当管道向上运动时，流入流量计的流体会抵抗向上运动的阻力，即向下推动管道。

• 另一方面，流出流量计的流体会抵抗向上运动的阻力，即向上推动管道。这种运动会导致管道发生扭转。

• 这种扭转运动由传感器感应，并直接与质量流量相关联。

• 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

什么是热式质量流量计？

What is a Thermal Mass Flow Meter? 

热式流量计最常用于测量洁净气体的质量流量，例如空气、氮气、氢气、氦气、氨气、氩气和其他工业气体。

其工作原理如下：

• 通过监测气流流经加热式传感器时的冷却效应来工作。

• 气流流经两个 PT100 型 RTD 传感器。

• 温度传感器监测实际气体过程温度，而自加热式传感器则通过改变流经它的电流来保持恒定的温差。

• 流经加热式传感器的质量流量越大，维持恒定温差所需的电流就越大。

• 因此，估算的加热器电流即可用于估算气体质量流量。

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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