CN115655990A - Method and device for measuring particle fineness of gas-solid two-phase flow - Google Patents
Method and device for measuring particle fineness of gas-solid two-phase flow Download PDFInfo
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- CN115655990A CN115655990A CN202211317978.1A CN202211317978A CN115655990A CN 115655990 A CN115655990 A CN 115655990A CN 202211317978 A CN202211317978 A CN 202211317978A CN 115655990 A CN115655990 A CN 115655990A
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Abstract
The application relates to a method and a device for measuring the particle fineness of a gas-solid two-phase flow, wherein the method comprises the following steps: acquiring an acoustic emission signal generated by particles in the pipeline according to the acoustic emission sensor; determining from the acoustic emission signal that all particle sizes detected per unit time are greater than d l Mass m of the particles j And particle diameter d j (ii) a According to mass m j And particle diameter d j Determining the total mass M of the particles with the particle diameter larger than d d (ii) a According to the particle diameter d of the particles and the total mass M of the particles d Multiple sets of measured values (d) i ，M di ) The total mass M of the particles after correction is obtained by fitting 0 (ii) a According to M d And M 0 Determining the fineness number R of the particles d . Through the embodiment of the application, more accurate particle fineness measurement and particle size distribution measurement can be given.
Description
Technical Field
The application relates to the technical field of online measurement of gas-solid two-phase flow, in particular to a method and a device for measuring the particle fineness of the gas-solid two-phase flow.
Background
In some industrial processes, a gas stream flows in a pipeline carrying particles, completing some necessary process flows. For example, in a coal-fired power plant, wind (coal) powder is used as fuel and enters a boiler through a pipeline to be combusted and generate power. The dusty gas stream is a two-phase stream comprising a gas phase and a solid phase. The solid phase is composed of a large number of particles of different sizes, and the particle size distribution is an important parameter of the two-phase flow. For the wind-powder fuel, too much proportion of particles with too large particle size means that the combustion efficiency is reduced, so that the measurement of the particle size distribution has positive significance for combustion optimization.
For workerThe measurement of the particle size distribution of pipelines in the industrial field comprises an off-line method and an on-line method. The actual operation usually adopts an off-line method: the ratio of particles on the sieve, commonly referred to as "fineness", is given by taking samples from the pipeline and then screening in the laboratory. It represents the percentage by mass of the content of particles of a given size fraction, as the percentage R of the remaining weight of the particles above a sieve having a mesh size d (μm) d (%) is used. When multiple fineness values are determined, a measurement of the particle size distribution can be derived.
The on-line method is a dynamic real-time method for directly measuring the fineness of particles in a main pipeline or a bypass pipeline in an industrial process. The on-line method mainly includes an acoustic method and an optical method. Optical methods have particular problems in the dusty environment, while acoustic methods use acoustic signals detected by sensors to determine particle size. Because the sensor has certain sensitivity, when the particle size of the particles is less than a certain value d l In time, the amplitude of the sound signal is very small, and the sound signal is submerged in noise and can not be used for measuring the particle size any more. There is thus a lower limit to the measurement of particle size acoustically, and therefore for particle sizes smaller than d l How to calculate the total mass of the small particles on line in real time by a reasonable theoretical calculation method so as to give a corrected value of the total mass of the particles and finally obtain more accurate particle size distribution measurement is a problem to be solved urgently.
Disclosure of Invention
In view of the above problems, the present application is proposed to provide a method and apparatus for measuring particle fineness of a gas-solid two-phase flow, which overcome the above problems.
The technical scheme of the embodiment of the application is realized as follows:
the embodiment of the application provides a method for measuring the particle fineness of a gas-solid two-phase flow, which comprises the following steps:
acquiring an acoustic emission signal generated by particles in the pipeline according to the acoustic emission sensor;
determining from said acoustic emission signal that all particle sizes detected per unit time are greater than d l Mass m of the particles j And particle diameter d j Wherein j isA positive integer greater than or equal to 1;
according to the mass m of the groups of the particles j And particle diameter d j Determining the total mass M of the particles with the particle diameter larger than d d ；
According to the particle diameter d and the total mass M of the particles d Multiple sets of measured values (d) i ，M di ) Fitting to obtain the corrected total mass M of the particles 0 Wherein i is a positive integer greater than or equal to 1;
according to M d And M 0 Determining the fineness value R of the particles d 。
In the examples of the present application, the mass m of the particles is determined according to the groups of masses j And particle diameter d j Fitting to obtain the corrected total mass M of the particles 0 The method comprises the following steps:
according to the particle diameter d and the total mass M of the particles d Multiple sets of measured values (d) i ，M di ) Using the formula
Fitting to obtain the corrected total mass M of the particles 0 Uniformity index n of the particles and characteristic particle diameter d c 。
In the embodiment of the application, the M is d And M 0 Determining the fineness value R of the particles d The method comprises the following steps:
using formulas
Calculating to obtain the fineness value R of the particles d 。
In the examples of the present application, the mass m of the particles is determined according to the groups of masses j And particle diameter d j Determining the total mass M of the particles with the particle diameter larger than d d The method comprises the following steps:
for the total mass M of all particles larger than the particle diameter d d By the formula
Calculating outTo obtain, in turn, a plurality of sets of measured values (d) i ，M di )。
In an embodiment of the present application, the acquiring an acoustic emission signal generated by a particle according to an acoustic emission sensor includes:
the acoustic emission sensor comprises a waveguide rod, and a signal peak value p generated by particles impacting the waveguide rod is obtained j By the formula m j ＝g(v j ，p j ) Calculating to obtain the mass m of the particles j Wherein v is j The velocity at which the particles impact, said v j Detected by a particle flow rate sensor.
In the examples of the present application, the particle size d of the particles j By the formula
Where ρ is the particle density.
In addition, the embodiment of the application also provides a device for measuring the fineness of the particles of the gas-solid two-phase flow, which comprises an acoustic emission sensor, an acoustic wave transmission rod connected with the acoustic emission sensor and a particle flow velocity sensor; the device is used for detecting the distribution of the particles in the pipeline by adopting the method provided by the embodiment of the application.
In an embodiment of the application, the particle flow rate sensor is an electrostatic sensor or an optical sensor.
The embodiment of the application has at least the following beneficial effects:
the examples of the present application propose a description of the particle size d of the particles and the total mass M of the particles greater than this d On the basis, the embodiment of the application also provides an on-line measurement scheme which can quickly and accurately give parameter values, wherein the parameter values comprise all small particles (d < d) l ) Total mass M of 0 And further on the basis of the total mass M of the granules 0 Can give a more accurate fineness measurement R d (d＜d l ) And particle size distribution measurements.
Drawings
Fig. 1 is a schematic diagram of a device for measuring particle fineness of a gas-solid two-phase flow provided by an embodiment of the application.
FIG. 2 is a schematic diagram of a process for measuring particle fineness of a gas-solid two-phase flow provided by an embodiment of the present application.
FIG. 3 is a schematic diagram of an acoustic emission signal generated by a single particle impact provided by an embodiment of the present application.
Fig. 4 is a schematic diagram of determining parameters by a fitting method according to an embodiment of the present application.
Detailed Description
In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be described in further detail with reference to the attached drawings, the described embodiments should not be considered as limiting the present application, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.
In the following description, reference is made to "some embodiments" which describe a subset of all possible embodiments, but it is understood that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.
In the following description, references to the terms "first", "second", and the like, are only to distinguish similar objects and do not denote a particular order, but rather the terms "first", "second", and the like may be used interchangeably with the order specified, where permissible, to enable embodiments of the present application described herein to be practiced otherwise than as specifically illustrated or described herein.
Unless defined otherwise, all technical and scientific terms used in the examples of this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the embodiments of the present application is for the purpose of describing the embodiments of the present application only and is not intended to be limiting of the present application.
Referring to fig. 1, the device for measuring the fineness of particles in a gas-solid two-phase flow provided by the embodiment of the present application includes an acoustic emission sensor 1, an acoustic wave transmission rod 2 connected to the acoustic emission sensor, and a particle flow velocity sensor 3. The particle flow rate sensor 3 may be an electrostatic sensor, an optical sensor, or another type of flow rate sensor, which is not limited in this application.
In one embodiment, the device may be installed in-line in a pipe, using an electrostatic sensor to measure the flow rate of particles, while a waveguide rod is inserted into the pipe to conduct the impact of the particles to an acoustic emission sensor. The measurement of the particle size and the initial measurement of its distribution are given by processing of the acoustic emission signal in conjunction with the flow rate measurement. And using the method of the present application, a corrected final fineness and particle size distribution measurement is given.
FIG. 2 shows a schematic diagram of the collision between a particle and a waveguide rod when the mass of one particle is m j At a velocity v j When the acoustic wave impinges on the waveguide rod 2, the acoustic wave is guided along the waveguide rod 2 to the acoustic emission sensor 1 and converted into a voltage signal, and the output signal of the acoustic emission sensor is shown in fig. 3.
As shown in FIG. 3, the signal generated by particle impact has a peak value p j Mass m of it and particles j And velocity v at impact of the particles j Having a one-to-one non-linear relationship with
p j ＝f(v j ，m j )
(1)
To indicate.
By analyzing the signal as shown in fig. 3, the peak is obtained and knowing the velocity, the mass of the particle can be calculated efficiently. The measurement formula can be more accurately determined by calibrating the powder-containing air flow:
m j ＝g(v j ，p j )
(2)
the real particles are irregular in shape, the particles can be assumed to be spherical, and the particle diameter d of each particle can be calculated through the known particle density rho j ：
Therefore, the gas-solid two-phase particle fineness measuring device provided by the embodiment of the application can measure the mass of particles and the particle size of the particles. For the powder-containing gas flow, particularly a large number of particles are contained, but the impact area of the waveguide rod can be reasonably designed, so that the acoustic emission signal peak value of a single particle can be relatively independently distinguished, and the mass m of all the particles in a period of time can be online and real-timely j And particle diameter d j And recording the data one by one.
For calculating the particle size distribution of the particles, M is calculated for the total mass of all particles greater than the particle size d d Can be obtained by the following cumulative calculation
Since the acoustic emission signal has a minimum threshold value, the particle size detection also has a corresponding minimum value d l And thus when not corrected, the total mass of particle size greater than 0
Is not included in a particle size of less than d l The fineness value calculated from the total mass of the particles of (1) is not accurate.
Therefore, in order to obtain more accurate measurement of total mass and fineness, the embodiment of the application also provides a method for measuring the fineness of the particles of the gas-solid two-phase flow.
Particle fineness R d And the particle diameter d of the particles can be expressed by the Rosin-Rammler equation:
in the formula:
R d -particle fineness, which is the percentage of the mass of particles with a particle size greater than d to the total mass;
b- -a constant reflecting the degree of particle thickness;
d- -particle size in μm;
n- -uniformity index of the particles, an index reflecting the particle size distribution of the particles, depending on the form of the pulverizing apparatus.
Assuming that the total mass of all particles is M 0 The total mass of the particles larger than the particle diameter d is M d The particle fineness is substantially
As can be seen from the combination of equations (5) and (6),
in the examples of the present application, a characteristic particle diameter d is introduced c And (2) and
formula (7) is
The formula (8) describes the particle diameter d of the particles and the total mass M of the particles above this d The relationship between them. Wherein 3 unknown parameters M characterizing the relationship are included in equation (8) 0 ，d c N needs to be determined. By measured sets of measured values (d) i ，M di ) Wherein d is i ＞d l And I =1. 3 parameters M can be calculated and determined by the fitting method 0 ，d c ，n。
Referring to FIG. 4, an example is given in FIG. 4, M 0 ＝2mg，d c =50 μm, n =1.1, so that it can be determinedParticle diameter d of the particles and the total mass M of the particles greater than the particle diameter d d The functional relationship between the two is shown as a curve in the figure. That is, if there is more than d l Some measured values of (d) i ，M di ) The three parameters characterizing the curve can be determined by fitting. Wherein d is l Representing the particle size threshold that can be measured by the acoustic emission sensor, when the particle size is less than a certain value d, due to the sensitivity of the sensor l In time, the amplitude of the sound signal is very small, and the sound signal is submerged in noise and can not be used for measuring the particle size any more. Thus, there is a lower limit for the particle size measurement acoustically, i.e. the lower threshold is d l And (4) showing.
Specifically, in the embodiment of the present application, an acoustic emission signal generated by a particle in a pipeline is acquired according to an acoustic emission sensor 1;
determining from the acoustic emission signal that all particle sizes detected per unit time are greater than d l Mass m of the particles j And particle diameter d j Wherein j is a positive integer greater than or equal to 1;
and then to the mass m j Summing to determine the total mass M of the particles d (ii) a Further according to the particle sizes d of the plurality of groups of particles i And the total mass M of the particles with a particle size greater than d di Fitting to obtain the corrected total mass M of the particles 0 ；
According to M d And M 0 Determining a fineness value R of the corrected particles d The fineness value is determined by considering small particles (d < d) l ) Therefore, the method is more accurate than the prior art, and has positive significance in practical application, such as combustion optimization in a coal-fired power plant.
The above description is only an example of the present application, and is not intended to limit the scope of the present application. Any modification, equivalent replacement, and improvement made within the spirit and scope of the present application are included in the protection scope of the present application.
Claims (8)
1. A method for measuring the fineness of gas-solid two-phase flow particles is characterized in that,
acquiring an acoustic emission signal generated by particles in the pipeline according to the acoustic emission sensor;
determining from said acoustic emission signal that all particle sizes detected per unit time are greater than d l Mass m of the particles j And particle diameter d j Wherein j is a positive integer greater than or equal to 1;
according to the mass m of the particles j And particle diameter d j Determining the total mass M of the particles with the diameter larger than d d ；
According to the particle diameter d and the total mass M of the particles d A plurality of sets of measured values (d) i ，M di ) Fitting to obtain the corrected total mass M of the particles 0 Wherein i is a positive integer greater than or equal to 1;
according to M d And M 0 Determining the fineness value R of the particles d 。
2. The method for measuring the particle fineness of a gas-solid two-phase flow according to claim 1,
according to the particle diameter d and the total mass M of the particles d Multiple sets of measured values (d) i ，M di ) Fitting to obtain the corrected total mass M of the particles 0 The method comprises the following steps:
according to the multiple groups of the particle diameters d of the particles i And the total mass M of the particles di Using the formula
3. The method for measuring the particle fineness of a gas-solid two-phase flow according to claim 1,
said according to M d And M 0 Determining the fineness value R of the particles d The method comprises the following steps:
using formulas
Calculating to obtain the fineness value R of the particles d 。
4. The method for measuring the particle fineness of a gas-solid two-phase flow according to claim 1,
according to the mass m j And particle diameter d j Determining the total mass M of the particles with the particle diameter larger than d d The method comprises the following steps:
for the total mass M of all particles larger than the particle diameter d d By the formula
Calculated to obtain multiple groups of measured values (d) i ，M di )。
5. The method for measuring the particle fineness of a gas-solid two-phase flow according to claim 1,
the acquiring of acoustic emission signals generated by particles according to an acoustic emission sensor comprises:
the acoustic emission sensor comprises a waveguide rod, and acquires a signal peak value p generated by particles impacting the waveguide rod j By the formula m j ＝g(v j ,p j ) Calculating to obtain the mass m of the particles j Wherein v is j The velocity at which the particles impact, said v j Detected by a particle flow rate sensor.
6. The method for measuring the particle fineness of a gas-solid two-phase flow according to claim 1, wherein the particle diameter d of the particles j By the formula
And calculating, wherein rho is the particle density.
7. A gas-solid two-phase flow particle fineness measuring device is characterized by comprising an acoustic emission sensor, an acoustic transmission rod connected with the acoustic emission sensor and a particle flow velocity sensor; the device is used for detecting the distribution of particles in a pipeline by using the method as claimed in any one of claims 1 to 6.
8. The gas-solid two-phase flow particle fineness measuring device of claim 7, wherein the particle flow rate sensor is an electrostatic sensor or an optical sensor.
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