WO2013097053A1

WO2013097053A1 - Method and system for measuring solids flux in circulating fluidized bed

Info

Publication number: WO2013097053A1
Application number: PCT/CN2011/002229
Authority: WO
Inventors: 孟凡勇; 王维; 李静海
Original assignee: 中国科学院过程工程研究所
Priority date: 2011-12-29
Filing date: 2011-12-29
Publication date: 2013-07-04

Abstract

Disclosed are a method and a system for measuring solids flux in a circulating fluidized bed. The measuring method comprises the following steps: 1) selecting two cross-sections in the falling section of the circulating fluidized bed reactor as measuring planes; 2) for each measuring plane, continuously measuring the average volume fraction in the solid cross-section of the measuring plane with a fan-beam ray in a period of time; the fan-beam ray being a fan-beam-shaped ray capable of penetrating the solid material in the reactor; 3) calculating the cross correlation function R(τ) for the time functions of the average volume fractions of the solid cross-sections for these two measuring planes, calculating the time τ at the maximum value of the cross correlation function and taking the time τ as the time for the solid material to move from the upper measuring plane to the lower measuring plane, and in turn calculating the solids flux of the circulating fluidized bed. The measuring method does not interfere with the flow field in reactors, does not lead to artificial gap operations, has true and reliable measuring results and can be used in extreme measuring environments of high temperatures and high pressure and even toxic environments.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of gas-solid two-phase flow measurement technology, and more particularly to a circulating fluidized bed solid flux measurement method and measurement system. Background technique

Circulating fluidized bed reactors are widely used in petroleum smelting, chemical, metallurgical, electric power and other process industries, and have a great role in national production. Only by accurately judging the watershed where the flow field system in the reactor is located can the mass transfer heat transfer of the reactor be effectively adjusted, thereby improving the overall efficiency of the reactor. Among the many parameters reflecting the operating state of the circulating fluidized bed, the solid flux G _s is the most important parameter for determining the basin in which the system is located. Solid flux, also known as solid recycle flow rate, refers to the mass of solids passing through the unit cross-sectional area of the reactor per unit time. Existing circulating fluidized bed solid flux measurement methods include:

1) Valve method. The valve method is to install valves (such as butterfly valves, slide valves, flap valves, etc.) in the measuring section of the reactor. When measuring, close the valve, cut off the normal circulation circuit of the material, measure the differential pressure or observe the accumulated material height by weighing The method calculates the cumulative mass of material over a period of time to obtain the solids circulation rate of the system, ie the solid flux. For example: Chinese patent CN200810117401.X (Circulating fluidized bed material circulation flow rate measurement method and device) uses a flap valve. When measuring, the flap valve is activated to transfer the solid material to the metering section. The Chinese patent CN200810198396.X (the circulating flow rate measuring device and measuring method applied to the circulating fluidized bed) adopts the screen baffle method, and the screen baffle is used to block the solid flow during the measurement, and the baffle is measured for a certain period of time. The quality of the solid material accumulated on it is actually one of the valve methods.

2) Probe method. The probe method inserts the measuring probe into the interior of the reactor, measures a series of local solid fluxes, and then performs integral summation calculation to obtain the solid flux of the whole system. Commonly used probes include fiber optic probes, momentum probes, and extraction probes. For detailed measurement of the probe method, refer to Ye, S., XB Qi, and J. Zhu, Direct Measurements of Instantaneous Solid Flux in a Circulating Fluidized Bed Riser using a Novel Multifunctional Optical Fiber Probe. Chemical Engineering & Technology, 2009. 32( 4): p. 580-589.

3) Tracer particle method. The tracer particle method is to add tracer particles to the interior of the reactor, and the global solid flux of the reactor is calculated by measuring the velocity of the tracer particles. For details of the tracer particle method, refer to Bhusarapu, S., et al, Measurement of overall solids mass flux in a gas-solid circulating fluidized bed. Powder Technology, 2004. 148(2-3): p. 158-171.

In addition, researchers have attempted to measure the solid flux of a circulating fluidized bed using a rotating impeller, piezoelectric sensor, and the like.

A common feature of the above methods is that they are all intrusive measurements. The intrusive measurement process will interfere with the flow field to varying degrees, and even cause the material flow to be interrupted, which will seriously interfere with the material balance and pressure balance of the flow system, resulting in artificial gap operation. Moreover, the measurement components of the interventional measurement are directly in contact with the flowing material. The static electricity generated by the friction of the material may interfere with the sampling of the instrument, affecting the authenticity and reliability of the measurement results. Moreover, since the industrial reactor is often in a high temperature, high pressure or even toxic extreme environment, there is a high requirement for the sealing property. Interferometric methods are difficult to generalize for use in such reactors. The interference-free measurement of solid flux has always been a difficult point in the field of circulating fluidized bed research.

In summary, there is an urgent need for a non-intrusive circulating fluidized bed solid flux non-interference in-situ measurement method and measurement system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-intrusive circulating fluidized bed solid flux non-interference in-situ measurement method and measurement system.

In order to achieve the above object, the present invention provides a circulating fluidized bed solid flux measuring method comprising the following steps:

1) selecting two cross sections as the measuring surface in the descending section of the circulating fluidized bed reactor;

2) for each measurement surface, continuously measuring the average volume fraction of the solid section of the measurement surface over a period of time using a fan beam; the fan beam is a beam of a fan beam shape capable of penetrating the solid material in the reactor;

3) Calculate the cross-correlation function H(T) of the time function of the average volume fraction of the solid sections of the two measuring faces, find the time lag r which maximizes the value of the cross-correlation function, and then calculate the circulating fluidization The solid flux of the bed.

Wherein, the circulating fluidized bed solid flux measuring method has a spacing of 100 mm to 1500 mm between the two cross sections.

Wherein, in the step 1), the position and the spacing of the two measuring surfaces of the descending segment are flexibly adjusted; in the step 2), for the position combination of each measuring surface, the fan beam is continuously used for a period of time. Measuring the average volume fraction of the solid section of the measuring surface Rate; in the step 3), the cross-correlation function R(T) of the time function of the solid cross-sectional average volume fraction of the two measuring faces is calculated for each position of the measuring surface, and the cross-correlation function Λ is found τ) take the position combination of the measuring surface of the maximum value and the time lag amount r and use the time lag amount r as the time taken for the solid material to move to the lower measuring surface at the upper measuring surface of the combined position, thereby calculating the cycle The solid flux of the fluidized bed.

Wherein, in the step 2), the fan beam is a fan beam X-ray or a fan beam γ-ray.

Wherein, the step 2) includes the following sub-steps:

21) Under the condition that there is no material in the reactor, the background ray attenuation signal is measured, and the reactor background ray attenuation signals Ι ₀₁ (ι) and 1 ₀₂ { ), I ₀₁ ( ) of the two measurement sections with the spacing d are obtained. with/. ₂ (i) representing the ray intensity measured at the ith pixel of the detector corresponding to the upper measurement surface and the lower measurement surface, respectively;

22) Under the condition that the solid materials in the measuring section of the reactor are closely packed, the ray attenuation signals I _fl ( ) and / _/2 (i) of the two measuring surfaces are measured, I _h (i) and / _/2 (i) respectively Representing the ray intensity measured at the ith pixel of the detector corresponding to the upper measurement surface and the lower measurement surface;

23) Under normal operation of the reactor, the ray attenuation signals I _tl ( and / _ί2 w of the two measuring surfaces are measured, and i _tl w and / _ί2 w represent the detectors corresponding to the upper measuring surface and the lower measuring surface. The ray intensity measured at i pixels;

24) Male ( = _£sf · { ni _t {i)/I. { ))/l _n (J _f ( )/I.^^ , Calculate the average volume fraction of solids on the ray penetration path corresponding to the i-th pixel of the detector, where £ _Sf is the solid state of the material Solid volume fraction;

25) according to the formula

Calculate the cross-sectional average solid volume fractions ^ and ^ of the upper measurement surface and the lower measurement surface, respectively, where is the distance of the ray corresponding to the ith pixel point through the reactor, L = ∑^ l{), n is the measurement The number of pixels of the detector corresponding to the face. ^3⁄4

Wherein, in the step 3), the cross-correlation function ^ (the maximum time lag r of the value is taken as the time taken for the solid material to move from the upper measuring surface to the lower measuring surface, according to the distance d between the two measuring faces, Calculate the moving speed of the solid material, and calculate the solid flux G _{s of the} reactor according to the average volume fraction of the section, the known material density, and the cross-sectional area of the reactor.

The present invention also provides a measurement system for the above measurement method, comprising a first radiation source, a first collimator, a first detector array, a second radiation source, a second collimator, and a second detector array The first radiation source is located above the second radiation source, and the first radiation source and the first collimator are disposed on one side of the detected circulating fluidized bed downcomer, the first radiation source a fan beam generated by the first collimator, the plane of the fan beam being perpendicular to an axis of the downcomer, the first detector array being disposed on the other side of the downcomer and located at the first source The generated fan beam ray is in a plane; the second ray source and the second collimator are disposed on one side of the detected circulating fluidized bed down tube, and the second ray source is generated by the second collimator The plane of the fan beam is perpendicular to the axis of the downcomer, and the second detector array is disposed on the other side of the downcomer and located in a plane of the beam of rays generated by the second source.

Compared with the prior art, the present invention has the following technical effects:

1. The invention does not interfere with the flow field in the reactor during measurement, and does not cause material flow interruption, and does not damage the material balance and pressure balance of the flow system to cause artificial gap operation.

2. In the present invention, no measuring component is directly in contact with the flowing material, and the measurement result is authentic and reliable.

3. The invention can be applied in extreme measurement environments with high temperature and high pressure and even toxic.

DRAWINGS

Figure 1 (a) is a view showing the structure of a measuring section and a measuring system of a circulating fluidized bed in an embodiment of the present invention;

Figure 1 (b) is a perspective view showing a stent platform in one embodiment of the present invention; Figure 2 is a flow chart showing an embodiment of the present invention;

Fig. 3 is a view showing the internal path length of the X-ray penetrating reactor corresponding to different pixel points; Fig. 4 is a time-series diagram showing the average solid volume fraction of the cross-section measured by the upper and lower measuring faces;

Figure 5 shows a cross-correlation analysis of the two time series in Figure 4;

Figure 6 shows the solid flux time series measured in one specific example.

BEST MODE FOR CARRYING OUT THE INVENTION For ease of understanding, the principle of the present invention for interference-free measurement of circulating fluidized bed solid flux is first described. It is well known that X-ray penetrating substances are attenuated. By calibration, a correspondence can be established between the thickness of the penetrating substance and the degree of ray attenuation, so that the average material of the measuring section can be calculated according to the degree of attenuation of the X-ray penetrating substance of the fan beam. The volume fraction ^ 7 , while using X-rays to measure in two sections of the reactor, can obtain the time function of the average volume fraction of the cross-section of the material through the two measuring faces (note that the actual measurement is constant The frequency is sampled and measured for the time series of the average volume fraction of the cross section). On the other hand, studies have shown that the particle group in the downcomer of the reactor moves as a whole at a speed of 4 mesh. (Ref: Bhusarapu, S., et al, Measurement of overall solids mass flux in a gas-solid circulating fluidized bed.

Powder Technology, 2004. 148(2-3): p. 158- 171. )„ When the solid material passes through the descending pipe section of the circulating fluidized bed, except for extreme conditions such as string gas, some materials will cause upward gravity movement of the material. The moving direction of the solid material is generally downward in the reactor, and the particle motion state is close to the moving bed. That is to say, after passing through the first measuring surface described in the foregoing, the particle group passes the second measurement after a certain time. a cross-sectional average volume fraction of the first measurement surface measured by the particle group at a first moment passing through the first measurement surface and a second measurement measured by the particle group at a second moment passing through the second measurement surface The average volume fraction of the cross-section of the surface is approximately the same. Therefore, after measuring the time function of the average volume fraction of the cross-section of the two measuring surfaces, the cross-correlation analysis can be used to obtain the movement of the particle group of the material from the first measuring surface. to the time of the second measuring surface, and thus obtain a moving velocity of the material TT _S. recombined with the volume fraction of the average cross-section, with a known density of the material of the reactor cross-sectional area can be calculated by material Shall mass per unit cross-sectional area is G _s, i.e., the solid flux reactor.

The invention will now be further described with reference to the drawings and embodiments.

In accordance with an embodiment of the present invention, a method of making interference-free measurements of circulating fluidized bed solids flux is provided. This measurement requires the use of a fan beam ray measurement system using radiation that is capable of penetrating the solid material in the reactor, such as X-rays or gamma rays. This embodiment uses X-rays.

Figure 1 (a) shows a schematic structural view of a measuring section and a measuring system of a circulating fluidized bed. The measurement system comprises a first radiation source 2, a first collimator 3, a first detector array 4, a second radiation source 5, a second collimator 6, a second detector array 7, an industrial computer 8, and a data acquisition computer. 9. The first source 2 is located above the second source 5. Both the first source 2 and the second source 5 are used to generate fan beam X-rays. The first detector array 4 and the second detector array 7 are both line arrays. Each detector array includes a plurality of detector units, which are also referred to as pixel points. One frame of X-ray signal data detected by the detector array is called a projection. The detector array used in this embodiment includes 1280 detectors. Pixels, so each projection includes 1280 raw data.

The first ray source 2 and the first collimator 3 are disposed on the detected circulating fluidized bed down pipe One side of the first ray source 2 passes through a fan beam generated by the first collimator 3, the plane of the fan beam ray is perpendicular to the axis of the downcomer 1, and the first detector array 4 is disposed at the descent The other side of the tube 1 is located in the plane of the fan beam generated by the first source 2 so that each detector unit receives X-rays to obtain projection data about the first measurement surface of the downcomer 1. Similar second ray source 5 and second collimator 6 are disposed on one side of the circulating fluidized bed downcomer 1 to be detected, and the second ray source 5 passes through the fan beam generated by the second collimator 6, the fan The plane of the beam ray is perpendicular to the axis of the downcomer 1, and the second detector array 7 is disposed on the other side of the downcomer 1 and located in the plane of the beam of rays generated by the second source 5 In order for each detector unit to receive X-rays, projection data about the second measuring surface of the downcomer 1 is obtained. The industrial computer 8 is connected to the first radiation source 2 and the second radiation source 5 for the first radiation source 2 and the second radiation source 5 to operate synchronously or time-divisionally. Synchronous work means that two sources emit X-rays at the same frequency for the same period of time. Time-sharing refers to the fact that two sources of radiation emit X-rays in different time periods. The data acquisition computer 9 is connected to the first detector array 4 and the second detector array 7, respectively, for receiving projection data collected by the first detector array 4 and the second detector array 7.

The first radiation source 2, the first collimator 3, the first detector array 4, the second radiation source 5, the second collimator 6, and the second detector array 7 are all fixed to a support platform having a lifting function on. As shown in FIG. 1(b), the bracket platform 10 includes a base 101 and a vertical rail 102 mounted on the base 101. The vertical rail 102 is mounted with a movable cantilever 103, and the movable cantilever 103 can be along the vertical rail 102. mobile. The first arm 104 and the second arm 105 are fixedly mounted at both ends of the moving cantilever 103, respectively. A first housing 106 is mounted on the first arm 104, and a first detector array 4 is mounted on the second arm 105. The first radiation source 2 and the first collimator 3 are mounted in the first casing 106, and the first casing 106 is provided with a through hole for the fan beam X-ray to pass therethrough. The mounting position of the first case 106 and the first detector array 4 is such that the first detector array 4 and the fan beam generated by the first source 2 are in exactly the same plane, and the plane is perpendicular to the measured segment (ie drop tube 1) the axis.

The base 101 has a first extending portion 107 and a second extending portion 108. The first extending portion 107 is fixed with a first mounting plate 109. The first mounting plate 109 is mounted with a second housing 110. The second housing 110 is mounted on the first mounting plate 109. The second source 5 and the second collimator 6 are mounted therein, and the second case 110 is provided with a through hole for the fan beam to pass through. A second mounting plate 111 is fixed to the second extending portion 108, and a second detector array 7 is mounted on the second mounting plate 111. The mounting position of the second tank no and the second detector array 7 is such that the second detector array 7 and the fan beam generated by the second source 5 are in exactly the same plane, and the plane is suspended Straight to the axis of the segment being measured (ie drop tube 1).

The basic flow of the radiation detection is that the first radiation source 2 located on the upper measurement surface emits X-rays, and after passing through the first front collimator 3, a fan-shaped X-ray beam is formed, which completely covers the circulating fluidization. The bed descending tube measures the upper section of the segment 1, the first detector array 4 detects the intensity of the beam, transmits the measurement signal to the data acquisition computer 9 for analysis and calculation, and the second source 5 and the lower portion of the lower measurement surface The detection flow of the second detector array 7 is the same. The time resolution of the measurement system depends on the ray photon integration time of the detector array. The integration time parameter used in this embodiment is lms. Therefore, the sampling frequency of the measurement system is 1000 Hz. In the present embodiment, the measured inner diameter of the riser of the circulating fluidized bed reactor (? is 411 mm, the inner diameter of the down tube (^ is 316 mm, the solid material in the reactor is glass beads, and the density is ^3⁄4 2500 kg/m ³ . The parameters of the system and the circulating fluidized bed reactor are all exemplary, and the present invention is not limited thereto, which is easily understood by those skilled in the art.

Figure 2 shows a flow chart of one embodiment of the present invention. Referring to Figure 2, the circulating fluidized bed solids flux measurement process comprises the following steps:

Step 1. Select two cross sections as the measurement surface in the descending section of the circulating fluidized bed reactor. In this embodiment, the distance d between the upper and lower measuring surfaces is 900 mm. However, it should be noted that the distance d between the two measuring surfaces has no fixed value and can be flexibly selected according to the measurement environment and the measured reactor structure and internal material type. The preferred range of the spacing d is from 100 mm to 1500 mm. The spacing d is determined by the principle that the correlation (correlation coefficient) of the cross-sectional average solid volume fraction sequence of the upper and lower measuring faces should be maximized. Of course, even if the value of the distance d does not satisfy the above principle, as long as the deviation is not large, the accuracy of the measurement result of the present invention is not significantly affected.

Step 2. For each measurement surface, the average volume fraction of the solid cross section of the measurement surface is continuously measured over a period of time using the fan beam ray.

According to an embodiment of the invention, this step may comprise the following sub-steps:

Step 21: When the circulating fluidized bed reactor is not running, that is, when the down tube measuring section is empty, the industrial computer 8 issues an instruction, and the X-ray scanning detecting devices of the upper and lower measuring surfaces simultaneously work, and the upper and lower measuring surfaces of the empty reactor are collected. Projection signal /. ^) and /. ₂ (i), i represents the pixel number of the detector array.

Step 22: The downcomer measuring section is filled with solid materials. Similar to step 21, the X-ray scanning detecting devices of the upper and lower measuring surfaces are simultaneously operated to measure the radiation attenuation signals of the two sections in the state of close packing of the materials/and/ _{or 2} (i). At the same time, the volume fraction of solids when the material is full is measured. In this embodiment, the volume fraction of solids when the material is full is 0.62.

Step 23. When the circulating fluidized bed reactor is in normal operation, the X-ray scanning detecting devices of the upper and lower measuring surfaces operate simultaneously, and the ray attenuation signals / and / _i2 (i) of the two sections in the normal operating state are measured.

Step 24. Calculate the average solid volume fraction of the cross-section of the upper and lower measuring faces ^ and ^. Where ^ is calculated as follows:

i~n i=l

£ _si (i) = e _Sf ■ {ln{I _tl {i)/I ₀₁ {i))/ln{I _h {i)/I ₀₁ (z))) ^ is calculated as follows:

i~n i=l

£ _S2 (i) = s _Sf ■ (ln(I _t2 (i)/I ₀₂ {i))/ln{If ₂ {i)/I ₀₂ («))) In this embodiment, n=1280 , Z (i) the distance of the ray corresponding to the ith pixel point through the reactor, the inner diameter of the reactor down tube is 316 mm, as shown in Figure 3, L = (i);

i=l The sampling frequency is 1000 Hz. Therefore, according to the above steps 21 to 24, the time series and ^ of the cross-sectional average solid volume fraction of the upper and lower measurement surfaces can be obtained, as shown in FIG. This gives the time function _w and the mean time fraction of the solid cross section of the two measuring faces, and t represents time. Step 3: Calculate a cross-correlation function 3⁄4(T) of the time function of the average volume fraction of the solid sections of the two measuring faces, find the time lag amount r that maximizes the value of the cross-correlation function and use the time lag amount r as The time taken for the solid material to move from the upper measuring surface to the lower measuring surface, and then the solid flux of the circulating fluidized bed is calculated.

In this step, according to the formula 3⁄4(T) = /_ ^∞ _∞ ^ (ί) ^(ί + _Τ ) ί3⁄4 , the cross-correlation operation is performed on the sum, where τ is the time lag and β( _τ ) is the two sets of signals. The correlation coefficient, * represents the conjugate complex number. According to the previous discussion, it can be seen that when ?W takes the largest At the time of value, the amount of time lag τ at this time is the time taken for the solid material to move from the upper measuring surface to the lower measuring surface. According to the actual measurement of the cross-correlation function H(T) according to the embodiment, as shown in the figure

As shown in Fig. 5, it can be seen that the time lag r of taking the maximum value is 201 ms.

Further, the average velocity ϋ^, TTs ^ d/r of the solid material passing through the two measuring faces is calculated, which is 4.48 m/s calculated in the actual measurement. According to the formula G _s = p _s - 1T _S - E _S - ^ _d ^ _r , the solid flux G _{s of the} reactor is calculated, where ^ is the inner diameter of the riser, which is the inner diameter of the down tube, which is the solid material in the reactor. density. ^ is the average solid volume fraction of the cross section. Since the average solid volume fraction of the cross sections of the two measuring faces is substantially the same, the average solid volume fraction of the cross section of any one of the measuring faces can be used. Since the measured average solid volume fraction of the cross section is a time series, the obtained G _s is also a time series, as shown in FIG. Further, the average solid flux value can be calculated to be 89.25 / 3⁄4f / (m ² , s;).

The inventors used the butterfly valve method to verify the measurement method proposed by the present invention at three different gas velocities, and the results are shown in Table 1.

Table 1

It can be seen that the results of the present invention and the butterfly valve method are substantially consistent, demonstrating the reliability of the method. It is worth noting that since the butterfly valve method can only measure the time average of the solid flux, the measurement result of the method of the present invention in the above comparative experiment is the time averaged average.

In addition, the principle of determining the spacing d between the two measuring faces mentioned above should maximize the correlation of the cross-sectional average solid volume fraction sequence of the upper and lower measuring faces. Therefore, in another embodiment, in step 1, the position and spacing of the two measuring surfaces of the descending segment can be flexibly adjusted, and in the step 2, for different combinations of measuring surface positions, respectively The fan beam ray continuously measures the average volume fraction of the solid cross section of the measurement surface over a period of time. In the step 3, the cross-correlation function of the time function of the solid cross-sectional average volume fraction of the two measuring faces is calculated for the position combination of each measuring face. R(r), find the position combination and time lag τ of the measuring surface which takes the maximum value of the cross-correlation function Λ(τ) and move the time lag amount r as the solid material at the upper measuring surface of the combined position to move down The time taken to measure the surface, and then the solid flux of the circulating fluidized bed is calculated.

The above-described embodiments are only intended to illustrate the invention, and should not be construed as limiting the scope of the invention. Further, it will be apparent to those skilled in the art that various modifications, variations and modifications which are not described in the above embodiments are protected by the present invention without departing from the spirit and scope of the embodiments. Within the scope.

Claims

Rights request

A method for measuring a solid fluid flux in a circulating fluidized bed, comprising the steps of:

3) Calculate the cross-correlation function ^3⁄4 of the time function of the average volume fraction of the solid sections of the two measuring faces (, find the time lag r which maximizes the value of the cross-correlation function, and then calculate the circulating fluidized bed Solid flux.

The circulating fluidized bed solid flux measuring method according to claim 1, characterized in that the circulating fluidized bed solid flux measuring method has a pitch of 100 mm to 1500 mm between the two cross sections.

The circulating fluidized bed solid flux measuring method according to claim 1, wherein in the step 1), the position and the spacing of the two measuring surfaces of the descending segment are flexibly adjusted; In the position combination of each measurement surface, the average volume fraction of the solid cross section of the measurement surface is continuously measured over a period of time using the fan beam ray; in the step 3), the position combination of each measurement surface is calculated. The cross-correlation function ϋ(τ) of the time function of the average cross-sectional volume fraction of the solid sections of the two measuring faces, find the positional combination of the measuring faces taking the maximum value of the cross-correlation function H(T) and the time lag amount r and The time lag amount r is taken as the time taken for the solid material to move to the lower measuring surface at the upper combined surface of the position, and the solid flux of the circulating fluidized bed is calculated.

The circulating fluidized bed solid flux measuring method according to claim 1, wherein in the step 2), the fan beam is a fan beam X-ray or a fan beam γ-ray.

5. The circulating fluidized bed solid flux measurement method according to claim 1, wherein said step 2) comprises the following substeps:

23) The ray attenuation signal of the two measuring surfaces under normal operation of the reactor i _tl w and / _ί2 w are measured, i _tl w and / _ί2 w represent the ray intensity measured at the ith pixel of the detector corresponding to the upper measurement surface and the lower measurement surface;

24) Calculate the average volume fraction of solids on the ray penetration path corresponding to the i-th pixel of the detector according to the formula ^^^ ^^)//^))/^/^)//^))), wherein f is the solid volume fraction of the solid material in a state of close packing;

25) According to the formula ^= 3⁄4^ _s (i) "(i)/L), calculate the cross-sectional average solid volume fractions ^ and ^ of the upper measurement surface and the lower measurement surface, respectively, where the i-th pixel point corresponds rays through a distance in the reactor, L {{), = Y ^ l n the number of measurement plane corresponding pixel detector. ^¾

The circulating fluidized bed solid flux measuring method according to claim 5, wherein in the step 3), the time lag amount r that maximizes the cross correlation function (r) is used as a solid material. From the time taken from the upper measuring surface to the lower measuring surface, the moving speed of the solid material is calculated according to the distance d between the two measuring faces, and then according to the average volume fraction of the cross section, the known material density, and the cross-sectional area of the reactor, The solids flux G _{s of the} reactor was calculated.

7. A measurement system for a circulating fluidized bed solid flux measurement method according to claim 1, wherein the measurement system comprises a first radiation source (2), a first collimator (3) First detector array (4), second source (5), second collimator

(6) and a second detector array (7); the first source (2) is located above the second source (5), and the first source (2) and the first collimator (3) are disposed a side of the circulating fluidized bed down pipe (1) to be detected, a first beam source (2) generates a fan beam ray generated by the first collimator (3), the plane of the fan beam ray and the down tube ( 1) the axis is perpendicular, the first detector array (4) is disposed on the other side of the downcomer (1) and located in the plane of the fan beam generated by the first source (2); The ray source (5) and the second collimator (6) are disposed on one side of the circulating fluidized bed down pipe (1) to be detected, and the second ray source (5) is generated by the second collimator (6) a fan beam, the plane of the fan beam being perpendicular to the axis of the downcomer (1), the second detector array (7) being disposed on the other side of the downcomer (1) and located in the second beam The source of the fan beam generated by the source (5) lies in the plane.

8. The measurement system according to claim 7, wherein the measurement system further comprises an industrial computer (8) and a data acquisition computer (9), the industrial computer (8) and the first radiation source (2) and the The two-ray source (5) is connected, and the data acquisition computer (9) is connected to the first detector array (4) and the second detector array (7), respectively.

9. The measurement system according to claim 7, wherein the measurement The system further includes a bracket platform (10) including a base (101) and a vertical rail (102) mounted on the base (101), and a movable cantilever (103) mounted on the vertical rail (102) The moving cantilever (103) is movable along the vertical rail (102), and the two ends of the moving cantilever (103) are respectively fixedly mounted with the first arm (104) and the second arm (105), the first A first housing (106) is mounted on the arm (104), a first detector array (4) is mounted on the second arm (105), and the first radiation source (2) is mounted in the first housing (106) And the first collimator (3).

10. The measurement system according to claim 7, wherein the base (101) has a first extension (107) and a second extension (108), and the first extension (107) is fixed a first mounting plate (109), a second housing (110) mounted on the first mounting plate (109), and the second source (5) and the second collimator mounted in the second housing (no) 6), a second mounting plate (111) is fixed on the second extending portion (108), and a second detector array (7) is mounted on the second mounting plate (111).