在沼气工程运行过程中，需要采用仪器去感知生产过程的状态。沼气工程中主要涉及两类检测仪表: 检测温度、压力、流量、液位等的热工测量仪表；检测固体悬浮物浓度、浊度、PH、COD、挥发性脂防酸、沼气成分等的物性与成分仪表。下面沼气生物脱硫设备厂家给大家简单介绍几种常用于自控系统的检测仪表，希望对大家有所帮助。
In the process of biogas engineering operation, it is necessary to use instruments to sense the state of the production process. In biogas engineering, there are mainly two kinds of measuring instruments: thermodynamic measuring instruments for detecting temperature, pressure, flow rate and liquid level; physical properties and composition instruments for detecting solid suspended matter concentration, turbidity, PH, COD, acid-proof volatile lipids, biogas composition, etc. The following biogas biological desulfurization equipment manufacturers give you a brief introduction to several commonly used automatic control system testing instruments, hoping to help you.
1.压力检测仪表
1. Pressure measuring instruments
电测式压力检测仪表是利用金属或半导体的物理特性，直接将压力转换为电压或电流信号输出。也可利用弹性体受压产生的形变，通过电阻应变片将形变转换为电压或电流信号输出。为保证弹性元件工作在有效形变范围内，被测大压力值不应超过满量程的3/4，小压力值不应低于全量程的1/3。
Electrical pressure measuring instrument is to use the physical characteristics of metal or semiconductor to directly convert pressure into voltage or current signal output. The deformation of elastomer under pressure can also be transformed into voltage or current signal output by resistance strain gauge. In order to ensure that the elastic element works within the effective deformation range, the maximum pressure measured should not exceed 3/4 of the full range, and the minimum pressure should not be less than 1/3 of the full range.
压力传感器获取的压力信息，由压力变送器或压力开关转换为标准电信号输出，可以远程输出。由传感器、变送器或压力开关组成的压力检测仪可用于监测管道、沼气发酵装置以及储气装置内的压力。压力测量值常常用作报警参数。
Pressure information acquired by pressure sensor can be converted from pressure transmitter or pressure switch to standard electrical signal output, which can be output remotely. The pressure detector composed of sensors, transmitters or pressure switches can be used to monitor the pressure in pipelines, biogas fermentation devices and gas storage devices. Pressure measurements are often used as alarm parameters.
2.流量检测仪表
2. Flow meter
流量检测仪表包括测量单位时间流量的流量计和测量流体流过总量的积算仪，多数流量检测仪同时具备测量流量和总量的功能。
Flow detection instruments include flow meters for measuring unit time flow and accumulator for measuring total flow of fluid. Most flow detectors have the function of measuring both flow and total flow.
检测流量的方式很多，其中电磁流量计因其传感器的光滑测量管内无阻流部件，使仪表压力损失极小，且不易堵塞，在检测液固两相介质流量方面有优势，故具有一定导电率的污水流量适合用电磁流量计检测，但若污水中含有较多铁磁性物质及大量水泡时会影响测量精度。电磁流量计在安装上要求前、后都有直管段，其长度分别不小于5倍、3倍管内径。
There are many ways to detect the flow rate, among which the electromagnetic flowmeter has advantages in detecting the flow rate of liquid-solid two-phase media because of its smooth sensor without obstruction components, which makes the pressure loss of the instrument very small and is not easy to block. Therefore, the sewage flow with certain conductivity is suitable for the detection of electromagnetic flowmeter, but if the sewage contains more ferromagnetic substances and a large number of bubbles, it will affect the measurement. Quantity accuracy. The installation of electromagnetic flowmeter requires that there are straight pipe sections before and after installation, whose length is not less than 5 times and its diameter is 3 times respectively.
对沼气流量的检测，一般借用天然气的商用流量检测仪表。因沼气具有腐蚀性，故检测仪表的抗腐性和仪表价格之间存在矛盾。目前上的较为的技术为超声波气体测量技术，超声波流量计与传统的压差式流量计、涡街流量计、热式流量计相比，具有更强的抗腐蚀性，更宽的量程比和更小的压损，能够满足高压、大流量的气体计量要求，并且不存在易于磨损的机械可动部件，能保证长期使用精度不变，具有较高的测量精确性。值得一提的是，锐意自控自主研发的超声波沼气流量计BF-3000B还具备同时测量CH4浓度和沼气流量的功能。
For the detection of biogas flow, the commercial flow meter of natural gas is usually used. Because biogas is corrosive, there is a contradiction between the anti-corruption and the price of the instrument. At present, the leading technology in the world is the ultrasonic gas measurement technology. Compared with the traditional pressure differential flowmeter, vortex flowmeter and thermal flowmeter, the ultrasonic flowmeter has stronger corrosion resistance, wider range ratio and smaller pressure loss. It can meet the requirements of gas measurement with high pressure and large flow rate, and there is no mechanical movable parts which are easy to wear and tear. Long-term use accuracy is unchanged, with high measurement accuracy. It is worth mentioning that the BF-3000B ultrasonic biogas flowmeter, which is designed to be self-controlled and independently developed, also has the function of simultaneously measuring CH4 concentration and biogas flow rate.
3.温度检测仪表
3. Temperature Measuring Instrument
温度是影响微生物活性的主要因素之一，沼气发酵过程需要进行温度控制，因此，温度检测仪表不可或缺。温度传感器中，适用于检测沼气发酵料液温度的典型测温元件是热电阻，其测温电路采用不平衡电桥。
Temperature is one of the main factors affecting microbial activity. The fermentation process of biogas needs temperature control. Therefore, temperature detection instrument is indispensable. In temperature sensor, thermal resistance is a typical temperature measuring element suitable for detecting the temperature of biogas fermentation liquid, and its temperature measuring circuit adopts unbalanced bridge.
温度传感器直接安装在沼气发酵装置上，与变送器的距离可能较远，传感器与变送器的连接通常采用三线制接法，即用三根导线，其中一根串联在电源支路里，另两根分别接在两个相邻的桥壁上。三线制接法可基本消除连接导线造成的测量误差。
The temperature sensor is directly installed on the biogas fermentation device, which may be far away from the transmitter. The sensor and the transmitter are usually connected by three wires, one of which is connected in series in the power supply branch, and the other two are connected on two adjacent bridge walls. The three-wire connection method can basically eliminate the measurement errors caused by the connecting wires.
与温度传感器配接的二次仪表主要包括温度变送器、数字温度显示仪和温度巡检仪。
The secondary instruments connected with temperature sensors mainly include temperature transmitter, digital temperature display instrument and temperature patrol instrument.
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2019-05-15
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