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Coal-fired steam furnace

Coal-fired steam furnace

  • Categories:Solution field
  • Author:
  • Origin:
  • Time of issue:2019-04-18 17:08
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Coal-fired steam furnace

  • Categories:Solution field
  • Author:
  • Origin:
  • Time of issue:2019-04-18 17:08
  • Views:
Information

Summary

The combustion adjustment of thermal power plant boilers is critical to the safe and economic operation of the boiler, and the important parameter characterizing the furnace combustion and heat exchange conditions is the flame (smoke) temperature distribution of the furnace. Especially the flue gas temperature at the exit of the furnace. At present, armored thermocouples are generally used for temperature measurement, which basically can detect the change trend of furnace flue gas temperature.

The internal combustion conditions of the boiler are complicated. Due to the influence of fineness of coal powder, ratio of wind to coal and quality of coal powder, the front end of the thermocouple armored steel pipe will have coking, which will affect the measurement accuracy of the thermocouple. Secondly, thermocouples work in high temperature environments for a long time, and are affected by hot air shear and self-weight to bend them. When maintenance (replacement) is required, it cannot be pulled out directly from the temperature measurement hole. It is usually cut off and the bent part is directly inserted into the furnace. The operation is extremely troublesome, and the on-site environment is very bad (high noise, high temperature, narrow space, inconvenient operation). Therefore, the non-contact colorimetric thermometry red is introduced to replace the thermocouple. Field experiments show that infrared temperature measurement is simple to install, less maintenance, easy to operate, and long service life.

 

Specific target

1. Replace the thermocouple being used with a colorimetric temperature measuring device;

2. Continuous measurement of the flue gas temperature of the coal-fired boiler furnace;

3. Compared with the thermocouple temperature measurement, the maintenance amount is reduced;

4, automatic decoking and dust purging, eliminating the effect of coking on temperature measurement, basically achieving unattended;

5, reduce the cost of temperature measurement (the system can work continuously for more than four years in the case of normal cooling system).

 

Solution

The following two temperature measurement solutions are proposed for the field situation:

 

Option One:

System components: colorimetric temperature measuring equipment, scroll refrigerator, air cooling and lens cleaner, mounting bracket, electronic control system, cable.

The system consists of the functions of each unit: the colorimetric device is used for temperature measurement; the vortex cooler is used to generate low-temperature cooling air; the air-cooled and lens cleaner is used to protect the colorimetric thermometer from working in a safe ambient temperature, ensuring the instrument is used for a long time. The optical lens does not accumulate dust; the mounting bracket is used for system installation; the electronic control system is used to control whether the colorimetric temperature measuring device works. When the working environment temperature exceeds 45 °C, the power of the colorimetric temperature measuring system is cut off to ensure that it is at a safe temperature. Work to make it stable and reliable for long-term operation; the cable is used to measure the temperature digital transmission to the control room.

Installation: Install the temperature measurement system directly in front of the thermocouple temperature measurement hole, and measure the furnace temperature through a colorimetric thermometer.

Advantages: simple system structure and relatively low cost.

Disadvantages: When the temperature measuring hole has coking or dust accumulation, the field of view of the thermometer is blocked and cannot be accurately measured. When the coking is severe or the temperature of the temperature measuring hole is severe, the temperature cannot be measured.

 

Option two:

System components: colorimetric temperature measuring equipment, scroll refrigerator, air cooling and lens cleaner, mounting bracket, decoking system, electronic control system, cable.

The system consists of the functions of each unit: the colorimetric device is used for temperature measurement; the vortex cooler is used to generate low temperature cooling air; the air cooling and lens cleaner are used to protect the colorimetric thermometer from working in a safe ambient temperature, and Guarantee to use together for a long time. The optical lens does not accumulate dust; the mounting bracket is used for system installation; the decoking system is used to remove the coke or dust accumulation on the inner wall of the temperature measuring hole (the decoking time can be set freely according to the actual situation); the electronic control system: 1. Control colorimetric measurement Whether the temperature equipment works, when the working environment temperature exceeds 45 °C, cut off the power of the colorimetric temperature measurement system to ensure that it works at a safe temperature, so that it can operate stably and reliably for a long time. 2. Set the decoking cycle and perform the decoking action; the cable is used to measure the temperature digital transmission to the control room.

Installation: Install the temperature measurement system directly in front of the thermocouple temperature measurement hole, and measure the furnace temperature through a colorimetric thermometer.

Advantages: Automatic de-focusing, basically unattended. It greatly reduces the maintenance time and frequency of workers before the furnace.

 

Program Advantages and Key Equipment Overview

Program advantages:

The use of non-contact measurement and artificial intelligence assisted decoking greatly reduces the maintenance of temperature measurement. Reduce the labor intensity of workers and improve the efficiency of equipment use. The extremely high response speed of the colorimetric temperature measuring device enables real-time measurement of the furnace temperature change. The comparison of the actual test results shows that the temperature change in the furnace measured by the thermocouple is within 25 °C for a period of time, and the temperature range measured by the colorimetric temperature measuring device is within 70 °C. As far as visual observation is concerned, the brightness in the furnace changes significantly, and the temperature measurement value of the thermocouple does not change because the thermocouple measures the average temperature at the position where it is located, and does not react to the instantaneous temperature change.

Kirchhoff's law tells us that a very small change in the temperature of the target object can cause a large change in the amount of infrared radiation, which means that the infrared thermometer can be extremely sensitive to the change of the temperature of the object, which is also the high speed of the infrared thermometer. The theoretical basis of the response. Therefore, the colorimetric temperature measurement system can truly react to the furnace temperature change process.

 

Key equipment overview

1, Colorimetric thermometer

1.1 Colorimetric Thermometer Overview

 

The colorimetric thermometer uses a double color temperature measurement method, that is, the ratio of the energy of the two infrared bands radiated by the target object to determine the temperature of the object to be measured. Since the measurement result depends on the ratio of the radiated power of the two bands, the partial loss of the radiant energy has no effect on the measurement result. It can overcome the measurement error caused by the transmission medium with dust, smoke, water vapor; partial occlusion of the field of view, or measurement of the attenuation of the radiation caused by the change of distance. Particularly suitable for relatively harsh temperature measurement sites.

The colorimetric thermometer is equipped with a visual sighting system and a measured value display and parameter setting system. The visual aiming is convenient for the user to install the instrument, and the visual system can be used to intuitively understand the real-time working condition of the heating body; the measured value display and parameter setting system can display the current measured value in real time, and the display window can be freely set with the user parameter by the button. It is also possible to define the operating mode of the thermometer by means of user parameters, so double color measurement and monochrome measurement can be switched. The instrument is easy to operate.

In the process of using the infrared thermometer, the measurement error caused by the following reasons is generally encountered: 1. The surface state of the material oxidation changes, or the oxide and the parent material crack, causing a large measurement error; 2. Due to the material itself The emissivity is low, causing measurement errors; 3. Measurement errors due to poor measurement environment. The double color temperature measurement method can solve these measurement problems well.

 

1.2 Main technical parameters of colorimetric thermometer:

1.2.1, Measurement range: 600-1400

1.2.2, Basic error: 0.5 (±0.5% FS)

1.2.3, Repeatability: 0.2%

1.2.4, Distance coefficient: 280:1

1.2.5, Measuring distance: 0.56m-

1.2.6, Measurable minimum target: φ2mm (560mm)

1.2.7, Response time: <10ms

1.2.8, Slope compensation: 0.850-1.150

1.2.9, Emissivity: 0.10-1.00

1.2.10, Response wavelength range:

Double colors: 0.8-1.1μm & 0.4-1.1μm

Single color: 0.4-1.1μm

1.2.11, Temperature resolution: 0.5

1.2.12,Probe size: φ58×183mm

1.2.13, Analog output: 4-20mA

1.2.14, Communication interface: RS485

1.2.15, Working power: 24VDC

1.2.16, Power: <1.2W

1.2.17, Working environment: 0- 60, relative humidity 10-95% (no condensation 25-45)

1.2.18, Use standard: colorimetric thermometer industry standard JB/T 9240-1999

 

1.3, Colorimetric thermometer structure

http://1808030531.pool201-site.yun300.cn/repository/image/juH7dEVSSa-NKCnJd949HA.png

 

1.4, Colorimetric thermometer panel description

1 Measurement value display and parameter setting window.

2 Decimal shift button, each time the button is pressed, the decimal point moves by one digit, and the decimal point can be edited.

3 Visually aim the window, adjust the flange with the objective lens, and clearly aim and observe the target.

4 Parameter setting button, press and hold this button for 5s to enter the parameter setting state.

5 Number plus key, press this key once, the digit of the decimal point is increased by 1.

 

1.5, Wiring definition and connection method

 

Connector lead pin

Color of wire

Derivative wire defined

Six core wire

1

Red

24V

2

Blue

0V

3

Black

OUT

4

Yellow

+ OUT

5

Green

A

6

White

B

 

http://1808030531.pool201-site.yun300.cn/repository/image/tZ9MPr9sQiGFuTnsWwGV0g.png

The shielded wire is connected to the sensor housing and can be connected to the user equipment. When it is not possible to connect, it can be connected to the power ground.

1.6, Output selection

Analog signal output: 0-20mA, 4-20mA and 0-5VDC, the user can freely set according to the input specifications of the display control system.

RS485, there are two kinds of communication protocols available. When DKBUS485 is selected, it can be matched with the company's data acquisition software to realize real-time measurement of measurement data.

The serial port is a simplex transmission mode, the DKBUS485 protocol is selected, the communication rate is 9600 bit, the MODEBUS protocol is selected, and the communication rate can be set.

For process control or remote communication, an RS485RS232 converter is required to connect to the computer.

 

1.7, Aiming and distance coefficient

http://1808030531.pool201-site.yun300.cn/repository/image/UaWJskJ-QA2d8ReKDTqpWQ.png

Distance coefficient diagram

 

1 The field of view of the infrared thermometer is smaller than the effective diameter of the target to be measured, and the measured temperature is the target accurate temperature. It is recommended to use this temperature measurement scheme without special installation requirements.

2 The target is filled with the field of view of the infrared thermometer. The measured temperature is the exact temperature of the target, but it imposes high requirements on the installation, especially the aiming aspect.

3 The measured target is not filled with the infrared thermometer field of view, and the measured temperature is lower than the actual temperature.

4 Effective field of view of the infrared thermometer.

 

1.7.1 Distance coefficient

Distance coefficient: the optical resolution, the ratio of the distance L from the objective lens to the target to be measured and the effective diameter D of the measurable target, L:D. The distance coefficient of the colorimetric thermometer is L: D = 300:1, the minimum target diameter can be measured 2mm, and the probe to the measurable minimum target distance is 600mm. In the double color measurement mode, the measurement distance change and the inability to fill the field of view measurement have little effect on the accuracy. The following description is mainly for the monochrome measurement mode.

 

1.7.2 Aiming

The colorimetric thermometer uses a visual aiming method. In the aiming system, the reticle is "¤" shaped, and when the target object is at the center of the mark, the thermometer is aimed at the object to be measured.

 

1.8, Parameter settings

1.8.1 Slope Compensation Settings

In the double color measurement mode, measurement errors are caused by excessively harsh measurement environments, such as very high concentrations of dust, heavily contaminated glass windows, and condensation of the thermometer objective. At this time, the measurement error correction can be realized by the slope compensation.

 

1.8.2 Emissivity setting

In monochrome measurement mode, measurement error correction can be achieved by emissivity parameters.

1.8.3 Parameter Function Description

Parameter code

Parameter meanings

Direction

Setting rangs

C

Double-color choice

0 double color

1 single color

0-1

S

Slope

Correct measurement error

0.850-1.150

E

Emmissivity

Different measured target,it can correct the measured mistake that caused by material,degree of oxidation, smooth finish,geometric configuration and so on,and correct the system mistakes as well

0.01-1.00

cOEF

Filter coefficients

The occasion of interfere a lot, the response speed is not important, but it is necessary to start this parameter when the stability is very high, when cOEF is 20,there response speed is slower than 50ms

0-20

Addr

Postal address

It’s used to defined the communicated address of meter,the effective rangs is 1-32.the meters on the same communicate line should setup different Ad value

1-32

AHd

Peak value hold time

When rAD is one,this parameter is effective,the meter is at the measurement mode od peak value,the unit of time is second

10-120

rAd

Measurement mode

0 normal measurement mode

1 peak value measurement mode

2  Difference measurement mode

0-2

 

2, Air cooling and decoking system

2.1 Vortex cooling tube

Vortex principle: After the compressed air is injected into the vortex chamber of the scroll, the airflow rotates at a speed of up to one million revolutions per minute to the hot gas outlet of the scroll, and a part of the air flows out through the control valve, and the remaining gas is After blocking, the inner ring of the original gas is rotated in the opposite direction at the same speed and flows to the cold end of the scroll. During this process, heat is exchanged between the two streams, the inner loop becomes very cold, flows out of the cold end of the scroll, and the outer loop becomes very hot, flowing from the hot end of the scroll.

The vortex tube can efficiently generate low-temperature gas for cooling and cooling purposes, and the temperature and flow rate of the cold air flow can be controlled by adjusting the valve at the hot gas end of the vortex tube. The higher the gas outflow ratio at the hot gas end of the vortex tube, the lower the temperature of the vortex tube cold gas end gas flow and the corresponding decrease in flow rate. The vortex tube can reduce the original compressed air temperature by up to 70 .

 

2.2 Air cooling and lens blowing system

2.3 Decoking and dust system

The decoking and dusting system ensures long-term unattended operation of the system.

2.4 Electronic control system

The system control box is used to control whether the color temperature measuring equipment works. When the working environment temperature exceeds 45 , the power of the colorimetric temperature measuring system is cut off to ensure that it works at a safe temperature to ensure its long-term stable and reliable operation.

Project outline

1. Temperature measurement hole (using the temperature measurement hole of the current thermocouple, aperture 25mm)

2. Install the fixed position (design the mounting bracket independent of the furnace wall in front of the temperature measuring hole. Advantages: the temperature of the mounting bracket and the instrument installation position is the ambient temperature; the mounting bracket is fixed on the furnace wall on the furnace wall. Advantages: no occupation Peripheral location. Disadvantages: The temperature of the mounting bracket is higher than the ambient temperature.

3. The defocusing device (the temperature measuring hole is cokeed or blocked by dust accumulation, the colorimetric thermometer can not accurately measure the temperature. If the system comes with a decoking device, the system can remove the temperature measuring hole coking and dust accumulation by itself. Reduced the number of times maintenance is considered.

4, Air cooling system (because the ambient temperature is up to 50 degrees Celsius or above, in order to ensure long-term stable operation of the system, the colorimetric thermometer must be equipped with air cooling device, the cold air is provided by the vortex cooling tube. The system provides the cooling system over temperature alarm and automatic cut off the function of the colorimetric thermometer power supply. When the cooling effect cannot reach the design parameters, alarm and cut off the colorimetric thermometer power supply.)


 

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迪凯光电

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Tel:027-8750 9386   027-8750 9105
Add:Dingye building C block, International Enterprise Center, Optics Valley Avenue, Wuhan China  
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