On-line stack dust meter DFT-F3030
Introduction:
Dust instrument is mainly used for the boiler flue dust emission concentration, continuous monitoring and timing, and the test data in real time through the communication interface to the environmental protection departments at various levels, to facilitate the environmental protection departments at various levels on the efficiency of the boiler dust removal equipment monitoring and evaluation, to monitor and control the soot emissions at the same time, provide a scientific basis for reducing environmental pollution.
Principle of measurement
1. Lamber-- BEER’S Method
Because the object absorbs some of the visible light energy, the light intensity becomes weak and the object appears a certain color.If it's transparent, it's still transparent;If all the light is absorbed, the object is black.The absorption of light is governed by the two laws of physics, Lamber's law and the law of Beer. Lambert's law states that, at a certain wavelength, the absorption of light is proportional to the thickness of the absorbent material.Bill's law states that at certain wavelengths, the absorption of light is proportional to the concentration of the absorbent material.The lambert beer law can be written as follows:
Medium (such as transparent film, printing ink film, etc.);C is the concentration of the medium (the number of substances in the unit volume);The molecular extinction index or the absorbance index, which is called the absorbing object, is related to the molecular structure of the absorbing material, which is related to the wavelength of light exposure.For general absorption (such as neutral grey), approximate to constant;There are significant variations with different wavelengths, and the values vary widely for different wavelengths of color.Lambert, beer's law in the field of measurement technology has been widely used, but should pay attention to, lambert's law is limited to absorbing material is uniform, beer's law is limited to the concentration of the absorbing material in a certain range, when the concentration change, produce the phenomenon such as dissociation, aggregation is not established.
2. Principle of dust detection
According to lambert -- bill's law, the concentration of soot is measured by the dual optical method.In the case of light intensity I, the ratio of I/I0, the transmittance of the light transmission through the medium, the concentration of the particles in the flue gas.
Opaque D=Lg(0/I)=ACL.
Among them:
I -- - light intensity
O -- - Projection light intensity
A - - Absorption coefficient
C -- -- - media concentration
L - - the length of the medium aperture
Density: light density has the branch of transmission and reflection density, optical density is the object of incident light absorption degree of reflection, the optical density value, the greater the object color more dark opacity method of spectral reflection density instrument has two kinds of single photon processes and double optical path.
The double- light meter is located at the same end of the flue or chimney with the light source and receiver. The calibration of zero and range can be achieved.In order to ensure the accuracy and reliability of the instrument operation, the instrument must have automatic calibration function.The concentration calibration is the relationship curve of the quality concentration of the impenetrable and flue gas particles, and the concentration of particulate matter is determined by the relationship curve.
3, dust meter structure
By the launch, correction, backflush, reflection four parts.
The emission section includes: light source, correction, backflush.
Light sources include: power supply, laser.
Calibration includes: stepper motor, calibration carrier plate, lens group.
Backflush includes: Backflush blower.
4, dust test process
The entire dust test process by the A, B, C, D, E five steps to complete:
Each step stepping motor drives the turntable to rotate and replace the mirror body.
A, laser works for 150 seconds to stabilize the light source and the circuit is stable
B, Measured 100% optical signal record reference and measured data for balance comparison
C, Measured 25% optical signal record reference and measured data for linear comparison
D, Measured 50% optical signal record reference and measured data for range comparison
E Actual measurement
Features
1, Stable, mature, small size easy to install
2, Automatic compensation emissions monitoring technology, no drift, maintenance is very low
3, Far less than the optical projection method of the installation and commissioning workload
4, Automatic compensation system can compensate for the lens installation is not aligned caused by the error
5, Only test 2K HZ modulation light is not affected by external light
6, The measurement accuracy is high, directly to mg / m3 shows 0.001mg / m3 ~ 9999mg / m3
7, With online automatic calibration zero school cross function, calibration is simple and convenient
8, Measuring the diameter of the flue can reach 12m
9, Real-time report of high emissions or other adverse circumstances, with emission alarm and maintenance alarm
10, Even if the lens is close to 50% covered by dust can also be reliably measured
Technical Parameter :
(1) Measuring range: Measuring range: 0-3000mg / m3
Measuring distance L: 0-8 meters
(2) Measurement accuracy: 1000 mg / m3 ± the following: ± 1% FS
1000 mg / m3 ± or more: ± 6% FS
(3) Signal output: 4 ~ 20mA, RS232
(3) laser output power: 5mW
(5) Instrument operating voltage: 220 ± 20V 50Hz
(6) Ambient temperature: -35 ° C to + 50 ° C
(7) Relative humidity: 30% to 80%
5, Smoke and dust sampling probe instructions
Installation of the front end of the installation of smoke and dust probe: As shown above, the back blowing wall, soot probe transmitter, the transmitter back cover, dust probe receiver, etc. are connected with M6 *20 stainless steel bolts firmly. Flange with 1 ~ 2mm industrial rubber asbestos pad for sealing, anti-blowing tube with Diameter 20 reinforced plastic pipe and backflush chassis connected to the tube clamp are used to fasten. Purge the probe with compressed air requirements for clean, oil-free, dry gas, the required pressure of 0.4 ~ 0.7MPa; flow of 0.2 cubic meters / minute.
6, Parameter query and modify
DFT-F3030-type dust meter a total of four buttons used to operate, namely:
Modify key (CHANGE): used to enter the parameter modification state;
Right key (→): used to move the cursor, select the number to be modified;
Rise key (↑): used to modify the number, each press, the number of increase "1";
Confirm key (OK): Used to switch the parameters to be queried or to confirm the modified parameters.
DFT-F3030-type dust meter a total of 11 parameters can query, respectively:
0 dust concentration: the measured concentration of soot, unit: mg / m3;
1 transmitted light intensity: the flare (chimney) opposite to receive the laser light intensity;
2 Reference light intensity: laser light intensity at the launch of the flue (chimney)
3 correction factor: used to correct the measured value
4 optical path length: the distance from the laser transmitter to the receiving end of the flue (chimney) in meters;
5 Optical intercept: used to correct the optical path, the default value is 0;
6 Optical slope: used to correct the optical path, the default value is 1.0;
7 concentration intercept: used to correct the measured concentration, the default value is 0;
8 concentration slope: used to correct the measured concentration, the default value is 1.0;
9 transmission range: 4 ~ 20 current output corresponding to the range;
10 Calibration dust concentration: for automatic calibration, provided that the light path must be clean environment.
Modification of parameters:
(CHANGE), the first digit of the corresponding parameter will flash with the right key (→) with the up key (↑) to modify the data to the appropriate one. Value, press the OK key (OK) to save the modified parameters, then the corresponding parameter of the digital bit will stop flashing.
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