Online CEMS Gas Analyzer

1.Online CEMS Gas Analyzer project introduction

Online CEMS Gas Analyzer is used for on-line monitoring of SO2, NOx, O2 emissions, flue gas parameters (temperature, pressure, flow rate, humidity) and soot from various stationary sources.The Online CEMS Gas Analyzer launched by Fengtu Technology can continuously monitor SO2, NOX, 02 (standard, wet basis, dry basis and converted), particulate matter concentration, flue gas temperature, pressure, flow rate and other related parameters, and statistics of emission rates , total emissions, etc.Thus the measured data can be effectively managed.

Online CEMS Gas Analyzer consists of four required subsystems: gaseous pollutant (SO2, NOX, 02, etc.) monitoring, particulate matter monitoring, flue gas parameter (temperature, pressure, flow rate, etc.) monitoring, and data acquisition and processing.

Gaseous pollutant monitoring uses the extraction condensation method + phosphoric acid titration method for pretreatment.The principle is to use the ultraviolet differential method to measure the SO2 and NOX content in the flue gas, measure the wet oxygen content through the electrochemical method, and then calculate the SO2 through dry-wet conversion., NOX, 02 dry flue gas concentration, phosphoric acid titration hair pretreatment can effectively reduce the adsorption loss of SO2 during condensation and water removal, and improve measurement accuracy.

Particulate matter monitoring adopts the extraction measurement method, the temperature of the flue gas is measured by a temperature sensor, the flue gas pressure is measured by a pressure sensor, and the flue gas flow rate is measured by a pitot tube; all measurement signals are sent to the data acquisition and processing system.

The output processing system has functions such as real-time transmission of on-site data, remote fault diagnosis, report statistics, and graphic data analysis, enabling unattended work sites.The entire system has a simple structure, wide dynamic range, strong real-time performance, flexible networking, and low operating costs.At the same time, the system adopts a modular structure and is easy to assemble.It can fully meet the requirements for communication with the internal DCS system of the enterprise and the data system of the environmental protection department..

000011 Project Implementation Standards

The design, manufacturing, and acceptance specifications of this system are mainly carried out in accordance with the following standards and technical specifications:

u GB3095-1996 "Atmospheric Environmental Quality Standard"

u GB13223-2003 "Emission Standards for Air Pollutants from Thermal Power Plants"

u GB18485-2007 "Pollutant Control Standard for Domestic Waste Incineration"

u HJ/T75-2007 "Technical Specifications for Continuous Monitoring of Flue Gas Emissions from Thermal Power Plants"

u CJJ90-2002 "Technical Specifications for Municipal Domestic Waste Incineration Engineering"

u CJ/T118—2002 "Technical Specifications for Municipal Domestic Waste Incinerators"

u HJ/T76-2007 "Technical Requirements and Detection Methods for Continuous Monitoring Systems for Flue Gas Emissions from Stationary Pollution Sources"

u GB16297-1996 "Comprehensive Emission Standard of Air Pollutants"

u GB/T16157-1996 "Method for determination of particulate matter in exhaust from solid pollution sources and sampling method of gaseous pollutants"

u GB9078-1996 "Comprehensive Emission Standard of Air Pollutants for Industrial Kilns"

u GB 3095-1996 "Ambient Air Quality Standard"

u GB12519-1990 "General Technical Conditions for Analytical Instruments"

000012 project plan

000012.1 Measurement items

ØSO2, NOX, O2, smoke, temperature, pressure, flow rate

000012.2Measurement method

ØFume gas sampling method: extraction condensation method

ØSO2, NOX monitoring method: differential optical absorption spectrometry (phosphoric acid titration pretreatment)

ØO2 monitoring method: electrochemical method

ØSmoke and dust measurement method: extraction measurement method

ØTemperature measurement method: temperature sensor

ØPressure measurement method: pressure sensor

ØFlow velocity measurement method: Differential pressure method (Pitot tube)

2.General principles of Online CEMS Gas Analyzer system

The functional design, structure, performance, installation and testing technical requirements of this system equipment all comply with the relevant national environmental protection standards and meet the environmental protection industry standards of the People's Republic of China (HJ/T75-2007, HJ/T76-2007) Require.

The company's CEMS system consists of a gaseous pollutant monitoring subsystem, a particulate matter monitoring subsystem, a flue gas parameter monitoring subsystem and a data acquisition and processing subsystem.The gaseous pollutant monitoring subsystem and data acquisition and processing subsystem are installed in the standard Inside a 19-inch cabinet.The system composition is as follows:

Figure 1.CEMS system composition diagram

ØGaseous pollutant monitoring subsystem: composed of sampling unit, pretreatment unit and analysis unit.

ØParticulate matter monitoring subsystem: adopts extractive smoke and dust monitor.

ØSmoke gas parameter monitoring subsystem: Pitot tube is used to measure flow rate, pressure sensor is used to measure pressure, temperature sensor is used to measure temperature, and flue gas humidity is measured using high-temperature capacitive humidity sensor.

ØData acquisition and processing subsystem: composed of data collector, industrial computer, display and system software.

The above subsystems are tailored according to different customer needs.

Figure 2.CEMS system installation diagram

3.System composition

3.1 Monitoring of gaseous pollutants

3.1.1 Sampling and preprocessing unit

The sample gas is taken out by the sampling probe under the force of the sampling pump.Most of the particulate matter in the sample gas is filtered out by the filter in the sampling probe.After filtering, it is transported to the refrigeration system by the heating pipeline to condense and remove water, and then sent to the analysis unit for analysis.Among them, according to the common characteristics of high humidity and low SO2 in ultra-low systems, in order to reduce the adsorption loss of SO2, the pretreatment system adopts a relatively reliable and simple phosphoric acid titration method, adding more than 5% phosphoric acid solution in the condenser pretreatment, so that The condensed water is always in an acidic state, reducing SO2 adsorption loss and improving measurement accuracy.The condensed water is drained away through the drainage system.The control unit implements functions such as backflushing, calibration, and refrigeration temperature alarm prompts, and displays various working states of the system.

The pretreatment system uses one-stage rapid condensation to remove water to ensure that the gas composition remains unchanged.Two-stage fine filtration is used to ensure that the gas measurement chamber is not contaminated, thus extending the service life of the analyzer.The figure below is the flow chart of the gaseous pollutant monitoring system.

3.1.2 Gas analyzer

Instrument: UV Spectroscopic Gas Analyzer

Model: HM-UVA-100

Measurement principle: Differential optical absorption spectroscopy (DOAS)

Measurement principle

The ultraviolet spectrum gas analyzer is a gas analysis instrument based on multi-channel spectral analysis technology (OMA) and differential optical absorption spectrometry (DOAS).The light beam emitted by the light source converges into the optical fiber and is transmitted to the gas chamber through the optical fiber.After passing through the gas chamber, it is absorbed by the gas to be measured and then transmitted to the spectrometer by the optical fiber.It is split by the grating inside the spectrometer, and the array sensor converts the split optical signal.As an electrical signal, the continuous absorption spectrum information of the gas is obtained.The instrument uses differential absorption spectrum algorithm (DOAS) and partial least squares algorithm (PLS) to process based on this spectral information to obtain the concentration of the measured gas.

ØMulti-band spectral analysis technology (OMA)

Since various gas molecules absorb light waves differently in different wavelength bands, simultaneous measurement of multiple gases can be achieved by analyzing the continuous spectrum after gas absorption.

The UV spectrum gas analyzer uses a light source and sensor in the ultraviolet band to measure the concentration of gases that absorb light waves in the ultraviolet band, such as SO2, NO, NO2 and other gases.

ØDifferential optical absorption spectroscopy (DOAS)

The core idea of DOAS is to decompose the absorption spectrum of gas into two parts: fast changing and slowly changing parts.The fast-changing part is related to the structure and elements of the gas molecules, and is the characteristic part of the gas molecule absorption spectrum; the slowly-changing part is related to the interference of smoke, water vapor, background gas, and changes in the measurement system, and is the interference part.DOAS uses a fast-changing part to calculate the concentration of the gas being measured, and the measurement results are uninterrupted and have high accuracy.

The UV spectrum gas analyzer adopts a unique processing method that combines the DOAS algorithm and the PLS algorithm to eliminate the interference of smoke, water vapor, and background gases.It also eliminates the impact of measurement system fluctuations on the measurement results, ensuring the accuracy and accuracy of the measurement.stability.

Technical indicators

SO2: 0～20～100ppm (can be customized according to buyer’s needs)

NO: 0～20～100ppm (can be customized according to buyer’s needs)

Accuracy: ≤±2%

Linear error: ≤±2%FS

Zero point drift: ≤±2%FS/7D

Range drift: ≤±2%FS/7D

Response time: ≤30s

other

O2 measurement electrochemistry, 0～25%, ≤±2%FS

Power supply: 220VAC, 50Hz

Ambient temperature limit: -10～40℃

Communication interface: 1 channel RS232; 1 channel RS485/RS232

Digital interface: 4 relay outputs, 2 binary inputs

Analog interface: 5 channels 4~20mA output, 2 channels 4~20mA input

Instrument features

ØHigh reliability

It uses a pulse xenon lamp with a lifespan of 10 years as the light source and a curing spectrometer.It has no moving parts and is highly reliable.

ØCombined gas chamber design

The combined gas chamber design makes spectral adjustment easy and improves spectral intensity.

ØHigh measurement accuracy and good stability

Using the DOAS (Differential Optical Absorption Spectroscopy) algorithm, the measurement results are not interfered by smoke, moisture and other factors, and the measurement accuracy is high; at the same time, the DOAS algorithm also eliminates errors caused by instrument aging, and the measurement stability is good.

ØHighly intelligent and digital

It has multiple built-in high-performance processors, and high-speed data bus communication technology is used between the processors.Each module has powerful digital configuration and detection functions; it is simple to operate and easy to use.

ØRich user interface

Provides rich interfaces and can be easily integrated into various control and monitoring systems.Wireless or wired networks can be established through communication methods such as RS485 and RS232 to facilitate the daily operation, maintenance and management of the instrument.

ØComparison with common analyzers

Online CEMS Gas Analyzer3.1.3 analysis system

The analysis system consists of:

ØSampling unit (probe, filter, temperature controller);

The sampling unit of the FT-CEMS-B system mainly consists of a sampling probe and a heating pipeline.Install the sampling probe at an appropriate location in the flue (or chimney) in accordance with national regulations, collect the gas in the flue, and transport the gas to the heating box located inside the cabinet through the heating pipe.In order to ensure the accuracy of the measurement results, both the sampling probe and the heating pipeline adopt electric heating, which can keep the gas at a set temperature to prevent moisture in the gas from condensing.The length of the heating pipeline can be customized according to the actual needs of the buyer.

ØPretreatment unit (sampling pump, dehumidification, fine filtration, drainage, etc.);

The flue gas reaches the pretreatment system through the high-temperature sampling probe and the heating pipe.The pretreatment system is switched through the sampling ball valve and enters the condenser for steam and water separation.The condensed water is discharged in time through the peristaltic pump.After condensation and water removal in the condenser, it undergoes three-stage fine filtration.The device performs dust removal and filtration, and the processed clean dust-free and water-free sample gas enters the flue gas analyzer for analysis and measurement.

ØAnalysis unit (SO2, NO, NO2, O2);

ØSignal output (SO2, NO, NO2, O2 concentration, range conversion, calibration status, fault status, etc.);

ØOthers (gas circuit, circuit, etc.);

ØAnalytical instrument cabinet: 1800×530×730MM (height*depth*width).

3.2 Particulate Matter Monitoring

Instrument: Extractable smoke (powder) dust measuring instrument

Model: LFS1000-MO type

Measuring principle: laser extraction type

Technical parameter table:

Implementation standard: HJ/T 76-2007 Technical requirements and detection methods for continuous monitoring system of flue gas emissions from fixed pollution sources.

Product performance features:

The same-point speed measurement and sampling integrated probe is used to support accurate isokinetic sampling.

Supports simultaneous output of four parameters: flue temperature, flue pressure, flue flow rate, and flue concentration.

The instrument uses a variety of advanced technologies.Including: related noise cancellation technology, laser emission power stabilization technology, extremely low noise TIA, interference control and signal integrity design, and anti-harsh environment design technology, providing fast, reliable and accurate quantitative smoke and dust emission data.

Unique patented automatic calibration technology realizes automatic zero point and full scale calibration.The system automatically performs zero point calibration and full scale calibration every 24 hours.Both manual zero point calibration and automatic zero point calibration are supported.

It uses jet technology to extract part of the flue gas from the flue.It has a compact structure, simple installation, resistance to lightning strikes, harsh environments, low cost, and low maintenance.

The flue gas sampling and transmission processes are continuously heated and constant temperature to prevent measurement errors caused by the condensation of wet flue gas during the transmission process.

It adopts intelligent technology and has a display function that can display various test data and fault prompts in real time to facilitate on-site debugging and maintenance.

Unique equipment operating status prompts, temperature abnormality, and parameter abnormality prompts.

It has a power-off self-protection function.After a power outage, the backup battery is used to provide power, close the valve, and protect the internal structure.

3.3 Flue gas parameter monitoring

3.3.1 Temperature and pressure flow integrated probe (temperature, pressure, flow rate)

The structure of the temperature-pressure flow integrated probe measurement device mainly includes a micro-differential pressure transmitter, a static pressure sensor, a thermal resistor (or thermocouple), a pitot tube, a backflush solenoid valve, temperature and pressure compensation, etc.The measurement principle is: the primary pressure component adopts the traditional pitot tube measurement method.After correct installation, the full pressure and back pressure pressure tubes of the pitot tube will transmit the detected dynamic pressure and static pressure to the differential pressure transmitter respectively., the differential pressure transmitter converts the difference between dynamic pressure and static pressure into a 4~20mA square root proportional current and sends it to the data acquisition module of the distribution box, and the computer in the CEMS cabinet performs data processing.

The inner and outer surfaces of the pitot tube have been specially treated to effectively avoid flue gas corrosion and reduce dust adhesion.The backflush solenoid valve is mainly used for system backflush when measuring dirty gases (such as flue gas discharged from boilers): when the probe detection hole adheres to or accumulates dust and dirt, the solenoid valve is opened regularly or according to a predetermined program, and the compressed air is At the same time, two pressure pipes are connected for blowing operation, and the solenoid valve is in a closed state during normal measurement.

Technical features

l It can measure the temperature, pressure and flow rate of flue gas in real time, and output 4~20mA through 3-channel analog signal two-wire system.

l Automatically backflush the dynamic pressure and static pressure ends of the pitot tube at regular intervals.

l High measurement accuracy, good reliability, and can work continuously for a long time.

lEasy installation and wiring, low maintenance.

Technical indicators

ØMeasuring range: linear output 0-30m/s;

ØOutput signal: 4~20mA two-wire system;

ØMeasurement accuracy: ±2%FS;

ØVerification frequency: 12 months;

ØResponse time: <1s;

ØDifferential pressure (temperature, pressure) transmitter power supply: 24VDC, two-wire system;

ØDifferential pressure transmitter overvoltage limit: 4.0MPa;

ØPitot tube material: 304, 316L stainless steel;

ØNormally closed backflush solenoid valve power supply: 220VAC, 50Hz;

ØPitot tube insertion length: 500~2000mm optional;

ØPressure transmitter range: -5~+5kPa;

ØTemperature transmitter range: 0~300℃;

ØMedium temperature range: -40~500℃;

ØAmbient temperature: -40~85℃;

ØStorage temperature: 0~50℃;

ØStorage humidity: 0~85%RH.

ØMounting flange: DN50;

ØMaterial: SUS316L

The difference between conventional CEMS and ultra-low CEMS

Parameters and scope of conventional CEMS flue gas online monitoring system

Ultra-low CEMS+Ultra-low dust (this model is aimed at areas with strict environmental protection requirements, and flue gas and dust are independent structures)

Ultra-low CEMS flue gas emission continuous monitoring system

Monitoring parameters and range

Ultra-low emission dust monitoring system

Parameters and range

the difference:

1.The specific measurement ranges of equipment analyzers are different.

2.Equipment measurement parameters are different.For example, ordinary particulate matter measurement uses in-situ laser backscattering, and ultra-low particulate matter measurement uses extraction laser front scattering.

3.The air chambers of the analyzers are different.The ordinary analyzer has a single air chamber and the ultra-low analyzer has double air chambers.It has a small measuring range, a long optical path and higher accuracy.Ultra-low analysis adds a unique prism.Routine no.Make it more precise.

The choice between ordinary equipment and ultra-low equipment must be made correctly according to local policy requirements.