CN102519830A - Method and device for measuring concentration of coal powder - Google Patents

Method and device for measuring concentration of coal powder Download PDF

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Publication number
CN102519830A
CN102519830A CN2012100089548A CN201210008954A CN102519830A CN 102519830 A CN102519830 A CN 102519830A CN 2012100089548 A CN2012100089548 A CN 2012100089548A CN 201210008954 A CN201210008954 A CN 201210008954A CN 102519830 A CN102519830 A CN 102519830A
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measuring point
measuring
coal powder
pressure
pipeline section
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杨兴森
郝卫东
胡志宏
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
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Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
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Abstract

The invention discloses a method for measuring the concentration of coal powder. The method comprises the following steps of: 1) selecting an air flow parameter measurement point I and an air flow parameter measurement point II before and after powder conveying air flow and the coal powder are mixed on a primary air pipeline, setting the unmixed air flow parameter measurement point I at a position where the air flow is steady, and the coal powder and the air are going to be mixed, setting the mixed air flow parameter measurement point II at a position where the speed of coal powder particles reaches the speed of the air flow behind the mixed point, selecting a pipe section L as a flow pressure drop measurement pipe section from a horizontal straight pipeline after the speed of the coal powder particles reaches the speed of the air flow, and arranging static pressure measurement points for measuring the pressure drop of the straight pipe section at two ends of the pipe section L respectively; 2) measuring the static pressure P1 and the full pressure P before mixing; 3) measuring the static pressure P2 after mixing and the pressure drop deltaPLD of the pipe section L; and 4) calculating the concentration of the coal powder. The invention also discloses a measurement device for implementing the method. The method and the device for measuring the concentration of the coal powder are suitable for primary air pipelines of a middle warehouse-type powdering system boiler.

Description

The measuring method of coal powder density and measurement mechanism
Technical field
The present invention relates to boiler coal-ash measurement of concetration technical field, relate in particular to a kind of measuring method and measurement mechanism of coal powder density.
Background technology
Coal dust between each burner of pulverized coal firing boiler distributes security and the economy that directly has influence on the boiler plant operation, to the discharged nitrous oxides level of coal-burning boiler also important influence.Measuring the ducted coal powder density of wind is the important means of monitoring the burner operation conditions.To adopting the pulverized coal firing boiler of bin storage type pulverizing system, past people is calculated the coal powder density in the primary wind and powder potpourri through the air of measurement pulverized coal conveying and air mass flow and the temperature before and after the coal dust mixing according to thermal equilibrium; When adopting this method, the specific heat of coal dust is difficult to confirm that accurately deviation can appear in result of calculation when ature of coal fluctuates; And because temperature survey and thermally equilibrated hysteresis quality make measurement result also obviously lag behind the variation of concentration; Especially approaching at defeated powder air-flow and coal dust temperature, mix under the less situation of front and back temperature variation and can't adopt thermally equilibrated method to calculate coal powder density especially.The method that patent 99115956.X " measuring method of air, pulverized coal flow and concentration and control system thereof " adopts the pressure of measurement pulverized coal feed pipe horizontal segment and non-horizontal segment to fall is found the solution the concentration of coal dust.This method requires horizontal segment and non-horizontal segment that bigger signal difference is arranged, and signal difference is big more, and it is accurate more to measure, and usually receives the restriction of field condition in the application.Patent 01107746.8 provides the defeated powder gas flow temperature of a kind of bin storage type pulverizing system to change the Measure Method of Pulverized Coal when little; But this method is not carried out the consideration of system to the flow losses of breeze airflow, the problem that the coefficient modification method that is adopted has also brought coefficient to confirm.
Summary of the invention
The object of the invention is exactly to measure inaccurate problem for the coal powder density that solves prior art; A kind of measuring method and measurement mechanism of coal powder density are provided; Simply accurate, easy to implement, be applicable to and mix the less situation of front and back temperature variation, be particularly suitable for the measuring method and the measurement mechanism of a ducted coal powder density of wind of bin storage type pulverizing system boiler.
To achieve these goals, the present invention adopts following technical scheme:
The measuring method of coal powder density may further comprise the steps:
1) on airduct road, selects flow parameter measuring point I, mixed flow parameter measuring point II before defeated powder air-flow and the coal dust mixing; Steady air current place before flow parameter measuring point I before mixing is located at coal dust and air will soon mix; Pulverized coal particle speed reached the gas velocity place after mixed flow parameter measuring point II was located at mixing point; Confirm on the straight horizontal pipeline after pulverized coal particle speed reaches gas velocity that pipeline section L measures pipeline section as flow pressure drop, arranges the hydrostatic measuring point that is used to measure this straight length pressure drop respectively at the two ends of pipeline section L;
2) measure the preceding static pressure P of mixing 1With total head P;
3) measure mixed static pressure P 2Pressure drop Δ P with pipeline section L LD
4) basis μ = P 1 - P 2 - Δ P LD P - P 1 Calculate coal powder density.
Said pipeline section L is a starting point with measuring point II, and length equals the distance of measuring point I to measuring point II.
Said pipeline section L is after the measuring point II a bit to be starting point, and length equals the distance of measuring point I to measuring point II.
The measurement mechanism of coal powder density comprises total head-static pressure measurement element, hydrostatic measuring point, pressure measuring instruments, data Collection & Processing System; Total head-static pressure measurement element and hydrostatic measuring point are arranged on airduct road; Be connected with pressure measuring instruments, pressure measuring instruments outputs signal to data Collection & Processing System, and one time the airduct road is provided with measuring point I; Measuring point II, flow pressure drop is measured pipeline section L; Arrange at measuring point I place and to be used to measure the total head-static pressure measurement element of air-flow in the difference of the total head at this place and static pressure; The hydrostatic measuring point of the differential pressure of the static pressure at this place of layout measurement and measuring point I place static pressure at measuring point II place; Arrange the hydrostatic measuring point of the pressure drop of measuring pipeline section L at pipeline section L two ends, the pressure signal of each measuring point is connected to corresponding pressure measuring instruments, and the output of each pressure measuring instruments is connected to the data acquisition and processing (DAP) system.
Data Collection & Processing System comprises data acquisition board; Data collecting instrument, computing machine, data acquisition board transfers to data collecting instrument with signal; Computing machine and data collecting instrument communicate, and accomplish data computation, demonstration and record coal powder density and output coal powder density signal.
Use of the present invention and operation principle: the principle of this measuring method is based on defeated powder air-flow mixes front and back with coal dust energy balance, and the parameter before and after mixing with coal dust through the measurement air-flow is tried to achieve coal powder density.The mixing of air and coal dust, mobility status are: defeated powder air-flow is respectively P with static pressure, speed, the density that coal dust will soon mix preceding section air-flow 1, V 1, ρ 1Static pressure, speed, the density of the section air-flow when particle speed reaches gas velocity after mixing are respectively P 2, V 2, ρ 2The flow of general mood stream and pulverized coal particle is respectively M A, M PThe preceding pulverized coal particle of mixing is bordering on static, and speed can be ignored, and the speed of mixing the back pulverized coal particle is V P, mixing under the little situation of front and back temperature variation, ignore and mix the front and back temperature variation, and consider corresponding tube friction flow losses, can obtain following energy equation:
M A ( 1 2 V 1 2 + P 1 ρ 1 ) = M A ( 1 2 V 2 2 + P 2 + ΔP LD ρ 2 ) + M P · 1 2 V P 2 - - - ( 1 )
In the formula, Δ P LDAfter of the accelerating effect of eliminating air-flow to particle, the pressure drop that wind powder mixture flows and produced in this pipeline section, just wind powder mixture is in the tube friction flow losses of this pipeline section.
Because temperature variation is little, therefore, ρ 1≈ ρ 2Pipeline section before and after mixing is long-pending constant, so the speed before and after mixing is also constant basically, i.e. and V 1≈ V 2Because pulverized coal particle is very tiny, diameter is a micron dimension, and the speed of the final speed of pulverized coal particle and air-flow is very approaching after mixing, and there is V at 2 places in the cross section P≈ V 2≈ V 1
Therefore, the computing formula that can release coal powder density μ by (1) formula is:
μ = M P M A = P 1 - P 2 - Δ P LD 1 2 ρ 1 V 1 2 = P 1 - P 2 - ΔP LD P - P 1 - - - ( 2 )
Here, P is that air-flow is in the total head of mixing the place, starting section.At definite Δ P LDCan try to achieve required coal powder density by (2) afterwards.
Δ P LDConfirm it is the important step of measurement of concetration, this is because Δ P LDItself is closely related with coal powder density and gas velocity.For this reason, adopt following method to confirm Δ P LDAfter tested pipeline upper section 2, choose a straight horizontal pipeline section, the length of this pipeline section is identical with the distance in 1,2 in cross section.Because this moment, particle reached final speed, so the pressure drop of this moment no longer comprises the energy loss that acceleration causes to particle, the pressure drop of measuring this pipeline section is and calculates required flow losses Δ P LD
Beneficial effect of the present invention: the measuring method of the coal powder density of this invention only need be measured the static pressure of air-flow before mixing and the static pressure and the corresponding differential static pressure of total head and mixing back air-flow with measurement mechanism; Just can confirm the concentration of coal dust; Method is simple; Do not receive the restriction of field condition, can widespread use.
Description of drawings
Fig. 1 is a measurement mechanism structural representation of the present invention;
Fig. 2 is air of the present invention, coal dust mixed flow synoptic diagram.
Among the figure, 1-powder storehouse, 2-machine supplying powder, tube cell under the 3-, airduct road of 4-; 5-total head-static pressure measurement element, 6-differential pressure transmitter I, 7-differential pressure transmitter II, 8-differential pressure transmitter III, 8-data acquisition board, 10-data collecting instrument; The 11-computing machine, 12-measuring point I, 13-measuring point device II, 14-measuring point III.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described further.
Measure Method of Pulverized Coal, in conjunction with Fig. 1, Fig. 2, among the figure, 1-powder storehouse; The 2-machine supplying powder, tube cell under the 3-, airduct road of 4-, 5-total head-static pressure measurement element, 6-differential pressure transmitter I; 7-differential pressure transmitter II, 8-differential pressure transmitter III, 8-data acquisition board, 10-data collecting instrument; The 11-computing machine, 12-measuring point I, 13-measuring point II, 14-measuring point III.May further comprise the steps:
1) on airduct road, selects flow parameter measuring point I and mixed flow parameter measuring point II before defeated powder air-flow and the coal dust mixing; Steady air current place before flow parameter measuring point I before mixing is located at coal dust and air will soon mix; Pulverized coal particle speed reached the gas velocity place after mixed flow parameter measuring point II was located at mixing point; After measuring point II, choosing measuring point III, is pipeline section L between measuring point II and the measuring point III, and the length of pipeline section L equals the distance of measuring point I to measuring point II; Arrange hydrostatic measuring point at pipeline section L two ends, the pressure drop of measuring pipeline section L length by differential pressure transmitter III;
2) measure mixing preceding total head P and static pressure P 1Difference P-P 1
3) measure the preceding static pressure P of mixing 1With mixed static pressure P 2Difference P 1-P 2
4) the pressure drop Δ P of measurement pipeline section L LD
5) calculate the coal powder density coal powder density.Coal powder density by formula
Figure BDA0000130555270000041
calculates.
The measurement mechanism of coal powder density in conjunction with Fig. 1, comprises powder storehouse 1, machine supplying powder 2; 3, airduct roads 4 of following tube cell, machine supplying powder 2 connect with powder storehouse 1, following tube cell 3 respectively; Following tube cell 3 connects with an airduct road 4, and one time airduct road 4 is provided with measuring point I, measuring point II; Measuring point III, total head-static pressure measurement element 5 is arranged in measuring point I 12 places, and differential pressure transmitter I 6 measures air-flows poor at the total head at this place and static pressure; Differential pressure transmitter II 7 measures the difference of measuring point I 12 place's static pressure and measuring point II 13 place's static pressure; The distance that distance between measuring point III14 and the measuring point II 13 and measuring point I 12 and measuring point II are 13 is identical, and differential pressure transmitter III8 measures the differential static pressure between measuring point III14 and the measuring point II 13.The output of each differential pressure transmitter is connected to the data acquisition board 9 of data Collection & Processing System; Data acquisition board 9 transfers to data collecting instrument 10 with signal, and computing machine 11 communicates with data collecting instrument 10, accomplishes data computation, demonstration and record coal powder density and output coal powder density signal.
Though the above-mentioned accompanying drawing specific embodiments of the invention that combines is described; But be not restriction to protection domain of the present invention; One of ordinary skill in the art should be understood that; On the basis of technical scheme of the present invention, those skilled in the art need not pay various modifications that creative work can make or distortion still in protection scope of the present invention.

Claims (5)

1. the measuring method of coal powder density is characterized in that, may further comprise the steps:
1) on airduct road, selects flow parameter measuring point I, mixed flow parameter measuring point II before defeated powder air-flow and the coal dust mixing; Steady air current place before flow parameter measuring point I before mixing is located at coal dust and air will soon mix; Pulverized coal particle speed reached the gas velocity place after mixed flow parameter measuring point II was located at mixing point; Confirm on the straight horizontal pipeline after pulverized coal particle speed reaches gas velocity that pipeline section L measures pipeline section as flow pressure drop, arranges the hydrostatic measuring point that is used to measure this straight length pressure drop respectively at the two ends of pipeline section L;
2) measure the preceding static pressure P of mixing 1With total head P;
3) measure mixed static pressure P 2Pressure drop Δ P with pipeline section L LD
4) basis μ = P 1 - P 2 - Δ P LD P - P 1 Calculate coal powder density.
2. the measuring method of coal powder density as claimed in claim 1 is characterized in that, said pipeline section L is a starting point with measuring point II, and length equals the distance of measuring point I to measuring point II.
3. the measuring method of coal powder density as claimed in claim 1 is characterized in that, said pipeline section L is after the measuring point II a bit to be starting point, and length equals the distance of measuring point I to measuring point II.
4. the measurement mechanism that is used for the measuring method of the described coal powder density of claim 1 comprises total head-static pressure measurement element, hydrostatic measuring point, pressure measuring instruments, data Collection & Processing System; Total head-static pressure measurement element and hydrostatic measuring point are arranged on airduct road, are connected with pressure measuring instruments, and pressure measuring instruments outputs signal to data Collection & Processing System; It is characterized in that; One time the airduct road is provided with measuring point I, measuring point II, and flow pressure drop is measured pipeline section L; Arrange at measuring point I place and to be used to measure the total head-static pressure measurement element of air-flow in the difference of the total head at this place and static pressure; The hydrostatic measuring point of the differential pressure of the static pressure at this place of layout measurement and measuring point I place static pressure at measuring point II place; Arrange the hydrostatic measuring point of the pressure drop of measuring pipeline section L at pipeline section L two ends, the pressure signal of each measuring point is connected to corresponding pressure measuring instruments, and the output of each pressure measuring instruments is connected to the data acquisition and processing (DAP) system.
5. the measurement mechanism of the measuring method of coal powder density as claimed in claim 4; It is characterized in that said data Collection & Processing System comprises data acquisition board, data collecting instrument; Computing machine; Data acquisition board transfers to data collecting instrument with signal, and computing machine and data collecting instrument communicate, and accomplishes data computation, demonstration and record coal powder density and output coal powder density signal.
CN2012100089548A 2012-01-12 2012-01-12 Method and device for measuring concentration of coal powder Pending CN102519830A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105004879A (en) * 2014-04-17 2015-10-28 国家电网公司 Speed measuring method of coal dust air flow
CN106290585A (en) * 2015-06-09 2017-01-04 南京中能瑞华电气有限公司 Ultrasonic method coal powder density measurement data handling system based on pipeline processes
CN106546520A (en) * 2016-10-27 2017-03-29 中国航天空气动力技术研究院 Combustion powder apparatus for measuring concentration and measuring method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02112757A (en) * 1988-10-21 1990-04-25 Babcock Hitachi Kk Instrument for measuring concentration of particulate matter in piping
CN1117977C (en) * 2001-01-18 2003-08-13 山东电力研究院 Coal powder density measuring method and measuring controller
CN1128985C (en) * 1999-12-29 2003-11-26 西安交通大学 Measuring method of air and powdered coal flow and concn. and its controlling system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02112757A (en) * 1988-10-21 1990-04-25 Babcock Hitachi Kk Instrument for measuring concentration of particulate matter in piping
CN1128985C (en) * 1999-12-29 2003-11-26 西安交通大学 Measuring method of air and powdered coal flow and concn. and its controlling system
CN1117977C (en) * 2001-01-18 2003-08-13 山东电力研究院 Coal powder density measuring method and measuring controller

Non-Patent Citations (1)

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Title
杨兴森等: "乏气送粉锅炉一次风煤粉浓度的测量方法与应用", 《中国电力》, vol. 36, no. 4, 30 April 2003 (2003-04-30) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105004879A (en) * 2014-04-17 2015-10-28 国家电网公司 Speed measuring method of coal dust air flow
CN105004879B (en) * 2014-04-17 2017-12-08 国家电网公司 A kind of speed measurement method of breeze airflow
CN106290585A (en) * 2015-06-09 2017-01-04 南京中能瑞华电气有限公司 Ultrasonic method coal powder density measurement data handling system based on pipeline processes
CN106546520A (en) * 2016-10-27 2017-03-29 中国航天空气动力技术研究院 Combustion powder apparatus for measuring concentration and measuring method

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Application publication date: 20120627