孔板流量计量表在瓦斯混合气体中的应用

ZK标准孔板是测量流量的差压发生装置，配合各种差压计或差压变送器可测量管道中各种流体的流量。孔板流量计节流装置包括环室孔板，喷嘴等。孔板流量计节流装置与差压变送器或者U型压力计配套使用，可测量液体、蒸汽、气体的流量，因此孔板流量计广泛应用于石油、化工、冶金、电力、轻工等部门。

充满管道的流体，当它们流经管道内的节流装置时，流束将在节流装置的节流件处形成局部收缩，从而使流速增加，静压力低，于是在节流件前后便产生了压力降，即压差，介质流动的流量越大，在节流件前后产生的压差就越大，所以孔板流量计可以通过测量压差来衡量流体流量的大小。这种测量方法是以能量守衡定律和流动连续性定律为基准的。

智能节流装置（孔板流量计）是集流量、温度、压力检测功能于一体，并能进行温度、压力自动补偿的新一代流量计，该孔板流量计采用先进的微机技术与微功耗新技术，功能强，结构紧凑，操作简单，使用方便。

二、特点

▲孔板流量计节流装置结构易于复制，简单、牢固，性能稳定可靠，使用期限长，价格低廉。

▲孔板计算采用国际标准与加工

▲孔板流量计应用范围广，全部单相流皆可测量，部分混相流亦可应用。

▲标准型节流装置无须实流校准，即可投用。

▲一体型孔板流量计安装更简单，无须引压管，可直接接差压变送器和压力变送器。

智能型孔板流量计特点

▲采用进口单晶硅智能差压传感器

▲高精度，完善的自诊断功能

▲智能孔板流量计智能孔板流量计其量程可自编程调整。

▲智能孔板流量计可同时显示累计流量、瞬时流量、压力、温度。

▲具有在线、动态全补偿功能外，智能孔板流量计还具有自诊断、自行设定量程。

▲配有多种通讯接口

▲稳定性高

▲量程范围宽、大于10：1

智能型孔板流量计技术指标

▲高精度：±0.075%

▲高稳定性：优于0.1%FS/年

▲高静压：40MPa

▲连续工作5年不需调校

▲可忽略温度、静压影响

▲抗高过压

“瓦斯”是一种有毒的混合气体，主要含有甲烷和一氧化碳两种气体，常产生在矿井之中，如遇明火，即可燃烧，发生“瓦斯”爆炸，直接威胁着矿工的生命安全。因此，矿井工作对“瓦斯”十分重视，除去采取一些必要的安全措施外，有的矿工会提着一个装有金丝雀的鸟笼下到矿井，把鸟笼挂在工作区内。原来，金丝雀对“瓦斯”或其他毒气特别敏感，只要有非常淡薄的“瓦斯”产生，对人体还远不能有致命作用时，金丝雀就已经失去知觉而昏倒。矿工们察觉到达种情景后，可立即撤出矿井，避免伤亡事故的发生。

在测量瓦斯混合气体的流量时不能用带电源的流量仪表测量，因此在选择流量计测量时就必须了解瓦斯混合气体的特性。

什么是瓦斯？

瓦斯，说起它的另外一个名称沼气，可能大多数人就会明白许多。其实它是来自英文和俄文的不规范发音。Gas的原意就是气体，包括各种可燃和不可燃气体。瓦斯的主要成分是甲烷，它的化学元素符号是CH4，一种无毒、无味、无颜色，可以燃烧的气体。生活中广泛用来烧水，做饭，也可以用作照明。

在煤矿里它从煤岩裂缝中喷出。矿井瓦斯爆炸是一种热一链式反应（也叫链锁反应）。当爆炸混合物吸收一定能量（通常是引火源给予的热能）后，反应分子的链即行断裂，离解成两个或两个以上的游离基（也叫自由基）。这类游离基具有很大的化学活性，成为反应连续进行的活化中心。在适合的条件下，每一个游离基又可以进一步分解，再产生两个或两上以上的游离基。这样循环不已，游离基越来越多，化学反应速度也越来越快，zui后就可以发展为燃烧或爆炸式的氧化反应。所以，瓦斯爆炸就其本质来说，是一定浓度的甲烷和空气中度作用下产生的激烈氧化反应。的氧气在一定温度作用下产生的激烈氧化反应。

瓦斯爆炸产生的高温高压，促使爆源附近的气体以极大的速度向外冲击，造成人员伤亡，破坏巷道和器材设施，扬起大量煤尘并使之参与爆炸，产生更大的破坏力。另外，爆炸后生成大量的有害气体，造成人员中毒死亡。

用LG系列孔板流量计在测量瓦斯混合气体时它的差压通常是用“U”型管压力计引出瓦斯混合气体的压差，再通过人工计算的方法将它的流量计算出来。 这是当今国内测量瓦斯呵呵气体的zui安全zui有效zui常用的方法。因此在选择孔板流量计时要知道所测量的瓦斯混合气体的比重，工作温度，工作压力，zui大流量，zui小流量等参数。

英文版本：

ZK standard orifice plate is measured flow differential pressure generator, cooperate with all sorts of differential pressure gauge or differential pressure transmitter to measure all kinds of fluid flow in pipes. Orifice flowmeter throttle device including the ring chamber orifice, nozzle, etc. Orifice flowmeter throttle device with differential pressure transmitter or u-shaped pressure gage, can measure the rate of flow of liquid, steam, gas, so the orifice meter is widely used in petroleum, chemical, metallurgical, power, light industry and other departments.

Fluid filled with pipes, when they flow through the pipe of the throttle device, a beam to local contraction at the throttling of the throttle device, so that the flow velocity increases, the static pressure is low, so the throttling parts before and after the pressure drop is produced, the pressure difference, the greater the flow of medium flow, in the front and rear of the throttling parts the greater the pressure difference, so the orifice meter can be measured by the size of the pressure difference to measure fluid flow. This kind of measurement method based on the energy conservation law and the law of flow continuity as a benchmark.

Inligent throttling device （orifice meter） is integrating flow, temperature and pressure detection, temperature, pressure, and can automatically compensate a new generation of flowmeter, the orifice meter adopts the new technology of advanced computer technology and micro power consumption, strong function, compact structure, simple operation, easy to use.

Second, the characteristics of

Bring orifice flowmeter throttle device structure easy to copy, simple, firm, stable and reliable performance, long service life, low price.

Bring orifice calculation adopt international standards and processing

Bring orifice meter wide scope of application, all the single phase flow are measured, partially miscible flow can also be applied.

Bring about standard throttle device without real flow calibration, putting-in-service proactively.

Bring a body orifice meter installation is more simple, do not need to bring pressure tube, can be directly answering the differential pressure transmitter and pressure transmitter.

Inligent orifice meter

Bring imported monocrystalline silicon inligent differential pressure sensor

Bring about high precision, perfect the self-diagnosis function

Bring about inligent orifice plate flowmeter inligent orifice meter range can be adjusted from the programming.

Bring about inligent orifice meter can display at the same time the cumulative flow and transient flow, pressure, temperature.

Bring about have the functions of online, dynamic full compensation, inligent orifice plate flowmeter has since diagnosis, set range.

Bring is equipped with a variety of communication interface

Bring high stability

Bring about wide range range, greater than 10:1

Inligent orifice meter technical indicators

Bring about high precision: plus or minus 0.075%

Bring high stability, better than 0.1% FS/year

Bring high static pressure: 40 mpa

Bring work five years in a row without calibration

Bring negligible temperature, static pressure influence

Bring high resistance overvoltage

"Gas" is a toxic mixture of gases, mainly contain two kinds of methane and carbon monoxide gas, often produced in the mine, in case of fire, burning, can be an explosion, "gas" directly threatened the life safety of the miners. As a result, the mine work to attach great importance to "gas", to remove some necessary security measures, some men carrying a cage with a canary down to the pit, hang cage in the workspace. It turns out that the canary particularly sensitive to "gas" or other gases, as long as there is very weak "gas", is far from a deadly effect to human body, the canary is unconscious but faint. The miners notice arrived at the kind of situation, can immediay withdraw from the mine, avoid the happening of casualty accidents.

When measuring the flow of gas mixture can't use with power flow meter, so when choosing flowmeter measurement must understand the characteristics of the gas mixture.

What is the gas?

Gas, talking about it another name of biogas, probably most people will understand many. Actually it is from English and Russian is not standard pronunciation. Original intention is the Gas Gas, including various combustible and flammable. Gas of main composition is methane, and its chemical element symbol is CH4, a kind of non-toxic, tasess, no color, can burn gas. Life is widely used to boil water, cooking, can also be used for lighting.

It spewed from cracks in coal and rock in coal mine. Mine gas explosion is a kind of hot a chain reaction （also called chain reaction）. When explosive mixture to absorb a certain energy （usually leads from the fire source heat）, after the reaction of molecular chain is broken, dissociation into two or more than two free radicals （also known as free radicals）. This kind of free radical has a lot of chemical activity, become the reaction continuous activation center. Under suitable conditions, each free radicals can be further broken down again, to produce two or more than two free radicals. So circulates, more and more free radicals, chemical reaction rate is becoming more and more fast, finally can develop into the combustion or explosion of oxidation reaction. So, gas explosion in terms of its essence, is a certain concentration of methane and air medium under the action of intense oxidation reaction. Under a certain temperature to produce oxygen oxidation reaction.

Explosive source of high temperature and high pressure gas explosion, prompting nearby gas outward impact at great speed, causing casualties and damage of roadway facilities and equipment, raise a lot of coal dust and participate in the explosion, greater destructive power. In addition, after the explosion to generate a large number of harmful gas, killing people poisoning.

With LG series orifice meter in its differential pressure measurement of a gas mixture is usually use "U" type tube manometer leads to the pressure difference of gas mixture, and its flow calculation by using the method of manual calculation. This is today's domestic measurement of gas well gas of the safest and most effective method of the most commonly used. So when choosing orifice flow timing to know the measured gas mixture proportion, operating temperature, pressure, maximum flow and minimum flow parameters, such as.