JPH0758213B2 - Pulverized coal flow rate measuring method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the measurement of the flow rate of a two-phase fluid of pulverized coal and gas conveyed through a pipe by a densitometer and a correlation anemometer. The present invention relates to a method and apparatus with improved reliability. [Prior Art] When transferring a two-phase fluid of powder and gas through a pipe,
As a technique for measuring the flow rate, a correlation type flow rate measuring device as disclosed in JP-A-58-190719 is known. As shown in FIG. 3, this known device is provided with a densitometer 2 and a correlation velocity meter 3 which face a flow path in the pipe, in a part of the pipe 1 which conveys a two-phase fluid. The densitometer 2 has wide concentration detecting electrodes 4a, 4b provided across a flow path, and detects an increase in capacitance due to powder passing between the electrodes 4a, 4b, This is converted into an electric signal and the concentration signal ρ is output. The correlation velocity meter 3 has a distance L with respect to the fluid transport direction F.
It is composed of an upstream side detector 5 and a downstream side detector 6 which are arranged side by side, and each has a narrow flow velocity detecting electrode 5a, 5b and 6a, 6b which are provided across the flow path. The amount of change in capacitance due to the powder passing through the correlation anemometer 3 is converted into an electric signal, and the upstream electric signal U1 detected by the upstream detector 5 and the downstream electric signal detected by the downstream detector 6 The side electric signal U2 is output. As shown in FIG. 4, the delay time γ between the upstream electric signal U1 and the downstream electric signal U2 can be obtained from the cross-correlation coefficient between the two signals. That is, since both of these signals U1 and U2 are transmitted as a so-called fluctuation signal with the delay time γ, the powder flow velocity v is calculated from the distance L between the pair of detectors 5 and 6 and the delay time γ. It is calculated as v = L / γ. At this time, the concentration ρ of the powder is continuously measured as a change in capacitance proportional to the concentration. Therefore, when the cross-sectional area of the pipe 1 is D, the flow rate Q of the powder is Q = v × It is calculated as ρ × D. Thus, in the known device, the flow rate of powder in the two-phase fluid can be calculated by using the delay time γ obtained by the correlation method and the concentration signal ρ. [Problems to be Solved by the Invention] The known device is theoretically most practically excellent among many techniques proposed for measuring the flow rate of powder in a two-phase fluid. However, the present inventors have found that when this known device is used for measuring the flow rate of pulverized coal, the intended purpose cannot be achieved. That is, as described above, in order to measure the flow velocity of the powder in the known device, the flow velocity detection electrodes 5a, 5b and 6a, 6b in the upstream side detector 5 and the downstream side detector 6 are used to pass the particles. It is necessary to detect the change in the electrostatic capacity of the powder, and detect the delay time γ as a so-called fluctuation signal of the upstream electric signal U1 and the downstream electric signal U2 that appear as a time difference. However, in the case of pulverized coal, the relative dielectric constant (ratio with the dielectric constant of vacuum) is small (generally said to be 2 to 3), so The change is scarce and no obvious waveform can be obtained for the electric signals U1 and U2. That is, as shown in FIG. 5, electrical signals U1 and U2
The peak of the waveform at is extremely small, and it is difficult to detect the delay time γ due to the time difference as a so-called fluctuation signal. Therefore, the above-mentioned known device is not suitable for measuring the flow rate of pulverized coal, and a new invention must be expected separately. By the way, in the steel field, the amount of pulverized coal that can be burned at the tuyere of a blast furnace is said to be 120 kg / T pig.
Since there is no suitable instrument, operation is performed within the distribution accuracy of the distributor. Since the distribution accuracy is 3δ (δ: standard deviation) about ± 40kg / T pig, the above 120kg / T is actually used.
It is operated at 80kg / T pig which is 40kg / T pig lower than pig. Therefore, if it becomes possible to measure and control the flow rate of pulverized coal, it will be possible to load more pulverized coal by 40 kg / T pig than at present, and the coke (28
By replacing pulverized coal (8 yen / kg) with pulverized coal (8 yen / kg), it is possible to significantly reduce the cost of iron making. In the electric power field, nuclear power generation has problems in accidents and location conditions, and gas power generation has problems in raw material supply, so coal power generation is desired. However, the resources of good quality coal are becoming scarce,
Where abundant inferior coal must be used, it is difficult to achieve it unless pulverized coal flow rate measurement is possible.
That is, in order to burn inferior coal at high temperature, it is necessary to keep the flow rate ratio of air and coal accurate, and it is necessary to measure and control the highly accurate mixing ratio of pulverized coal and air. [Means for Solving the Problems] The present invention is achieved by improving the above-mentioned known device.
It is intended to provide a method and an apparatus capable of accurately measuring the flow rate of pulverized coal. Therefore, the place where the method of the present invention is configured as means is as follows.
A method for measuring the flow rate of a two-phase fluid by a densitometer and a correlation velocimeter provided facing a two-phase fluid flow of pulverized coal and gas: in a flow channel upstream of the correlation velocimeter, The point is to add a measurement reaction accelerator having a relative dielectric constant larger than that of pulverized coal to the two-phase fluid. At this time, it is preferable that the measurement reaction accelerator is added in a flow path downstream of the concentration meter and upstream of the correlation anemometer. Further, the device of the present invention is configured as a means: a densitometer and a correlation anemometer which are provided so as to face a flow path of a pulverized coal and a gas two-phase fluid; On the upstream side, a two-phase fluid is provided with a promoter supply device for adding a measurement reaction promoter having a relative dielectric constant larger than that of pulverized coal; The measurement reaction accelerator used in the method or apparatus of the present invention may be a powder made of a substance having a relative dielectric constant larger than that of pulverized coal, but a powder selected from iron, iron oxide and barium titanate may be used. Preferably. Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, a pipe 11 conveys a two-phase fluid 14 of pulverized coal 12 and a gas 13, and forms a flow path 15 for the fluid 14 conveyed in a conveyance direction F inside the pipe 11. In the pipe 11, the densitometer 16 and the correlation velocity meter are provided facing the flow path 15.
And a flow path downstream of the concentration meter 16 and upstream of the correlation anemometer 17 with respect to the transport direction F.
In 15, a supply device 19 for the measurement reaction accelerator 18 is provided. The densitometer 16 has a flow path 15 similar to the known device described above.
It has electrodes for wide concentration detection 16a, 16b sandwiched between the electrodes, detects the increase in capacitance due to the pulverized coal 12 passing between the electrodes 16a, 16b, and converts this to an electric signal. And output the concentration signal ρ. In addition, it is preferable that the densitometer 16 has a coupling structure that is interposed at a predetermined position of the pipe 11. The correlation anemometer 17 is composed of an upstream side detector 20 and a downstream side detector 21 which are arranged at a distance L with respect to the transport direction F of the flow path 15, like the above-mentioned known device, Narrow flow velocity detection electrodes 20a, 20 provided across the flow path 15
It has b and 21a and 21b. Therefore, the amount of change in the electrostatic capacitance due to the pulverized coal 12 passing through the correlation anemometer 17 is converted into an electric signal and detected by the upstream electric signal U1 detected by the upstream detector 20 and the downstream detector 21. The upstream upstream electric signal U2 is output, and the delay time γ
Can be shown. The correlation velocity meter 17 is also connected to the pipe 11
It is preferable to have a coupling structure that is inserted at a predetermined position of. The supply device 19 for the measurement reaction accelerator 18 stores the measurement reaction accelerator 18 in a reservoir 22 such as a hopper or a tank, and the measurement reaction accelerator 18 is flown from the reservoir 22 via a control valve 23.
It is equipped with a supply path 24 that leads into the inside of the unit. As a drive source for supplying the measurement reaction promoter 18 from the reservoir 22 into the flow path 15, the negative pressure in the flow path 15 through which the two-phase fluid 14 is sent is used to control the control valve 23. The measurement reaction accelerator 18 in the reservoir 22 can be automatically sucked into the flow path 15 when opened. Alternatively, a driving device such as a pump may be connected to the reservoir 22 so that the measurement reaction accelerator 18 is forcibly supplied into the flow path 15. This accelerator supply device 19
Also, it is preferable to use a coupling structure that is installed at a predetermined position of the pipe 11. The measurement reaction accelerator 18 may be a granular material or a powder made of a substance having a relative dielectric constant larger than that of pulverized coal, and the material thereof is not particularly limited. However, when the device of the present invention is applied to a pulverized coal supply facility in a blast furnace, there is no problem even if it is mixed in the blast furnace raw material, the relative dielectric constant is significantly larger than that of the pulverized coal, and the cost is low. Considering this, it is best to use iron and / or iron oxide particles or powder as the measurement reaction accelerator 18. In addition, as the measurement reaction accelerator 18, particles or powder of barium titanate having a relatively low cost and a high relative dielectric constant may be used. The particle size of these measurement reaction accelerators 18 is preferably approximately the same as the particle size of the pulverized coal 12 being conveyed. In the above configuration, the control valve 23 is temporarily opened by a predetermined amount each time when measuring the flow rate of pulverized coal according to the present invention, and the measurement reaction accelerator 18 in the storage body 22 is caused to flow by the required amount. Supply into path 15. The supplied accelerator 18 is mixed with the two-phase fluid 14 sent in the flow path 15, sent in the conveying direction F at the same speed as the pulverized coal 12, and passes through the correlation velocity meter 17. At this time, since the measurement reaction accelerator 18 has a larger relative dielectric constant than the pulverized coal 12, the upstream side detector 20 and the downstream side detector 20
The flow velocity detection electrodes 20a, 20b and 21a, 21b of 21 are detected as a large change in capacitance, and as a result, the upstream electric signal U1 and the downstream electric signal U2 output by both detectors 20 and 21 are detected. The waveform is much more obvious than the conventional case shown in FIG. 5, and the waveform shown in FIG. 2 is shown.
Therefore, it becomes easy to obtain the delay time γ as a so-called fluctuation signal of such signals U1 and U2, and the pulverized coal 12
The flow velocity v (v = L / γ) can be reliably obtained. Therefore, by obtaining the flow velocity v and the above-mentioned concentration ρ, the flow rate Q of the pulverized coal 12 in the cross-sectional area D of the pipe 11 is obtained.
The fact that (Q = v × ρ × D) is calculated is the same as in the above-described known device. The densitometer 16 may be installed on the downstream side of the accelerator supply device 19, but in this case, the indicated concentration value ρ indicates the concentration of the mixture of the accelerator 18 and the pulverized coal 12. , A correction calculation must be performed to remove the accelerator 18 from the value ρ.
On the other hand, when the densitometer 16 is installed upstream of the accelerator supply device 19 as in the above embodiment, the indicated concentration value ρ indicates the concentration of the pulverized coal 12 only. There is no need for correction. [Advantage of the Invention] According to the present invention, when applying the conventional two-phase fluid flow rate measuring method and / or apparatus using a densitometer and a correlation velocity meter to a two-phase fluid of pulverized coal and gas, the correlation velocity On the upstream side of the meter, a measurement reaction accelerator with a relative dielectric constant larger than that of pulverized coal is added, so the so-called fluctuation signal waveform of the upstream side electrical signal and the downstream side electrical signal by the correlation anemometer is revealed and both The time delay of the signal can be detected reliably and easily, and thus the flow rate of the pulverized coal can be detected accurately. For this reason, it becomes possible to easily measure the flow rate of pulverized coal, which was considered difficult to measure by the conventional correlation anemometer, and there is an effect that it can contribute to the development of various technical fields using pulverized coal.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS. 2 (1) (2).
Is a waveform diagram of a so-called fluctuation signal output by the correlation anemometer in the same embodiment, FIG. 3 is a sectional view showing a two-phase fluid flow rate measuring device according to a conventional example, and FIGS. 4 (1) (2) are the same. An ideal waveform diagram of the so-called fluctuation signal output by the correlation velocity meter in the conventional example, Fig. 5 (1) and (2) are so-called fluctuations output by the correlation velocity meter when the conventional example is applied to pulverized coal. It is a waveform diagram of the signal. 11 …… Piping, 12 …… Pulverized coal, 13 …… Gas, 14 …… Two-phase fluid,
15 …… flow path, 16 …… densitometer, 16a, 16b …… concentration detection electrodes,
17 …… Correlation velocity meter, 18 …… Measurement reaction accelerator, 19 …… Accelerator supply device, 20 …… Upstream detector, 21 …… Downstream detector, 20
a, 20b, 21a, 21b ... Electrodes for flow velocity detection.

Claims (5)

[Claims] 1. A method for measuring the flow rate of a two-phase fluid by a densitometer and a correlation velocimeter provided facing a flow path of a two-phase fluid of pulverized coal and gas, comprising: from the correlation velocimeter (17). Also in the upstream flow path, a method for measuring the flow rate of pulverized coal, characterized in that a measurement reaction accelerator (18) having a larger relative dielectric constant than pulverized coal is added to the two-phase fluid. 2. A method for measuring the flow rate of a two-phase fluid by a densitometer and a correlation velocity meter provided facing a flow path of a two-phase fluid of pulverized coal and gas, which is more than the densitometer (16). In the flow path on the downstream side and on the upstream side of the correlation anemometer (17), a measurement reaction accelerator (18) having a relative dielectric constant larger than that of pulverized coal is added to the two-phase fluid. How to measure the flow rate of pulverized coal. 3. The measurement reaction accelerator (18) is iron, iron oxide,
The method for measuring the flow rate of pulverized coal according to claim 1 or 2, wherein the powder is a powder selected from barium titanate. 4. A densitometer and a correlation anemometer which are provided so as to face a flow path of a pulverized coal and a gas two-phase fluid; a downstream side of the densitometer (16) and an upstream side of the correlation anemometer (17). Of the pulverized coal, comprising: an accelerator supply device (19) for adding a measurement reaction accelerator (18) having a relative dielectric constant larger than that of the pulverized coal in the two-phase fluid. Flow rate measuring device. 5. The measurement reaction accelerator (18) is iron, iron oxide,
The pulverized coal flow rate measuring device according to claim 4, wherein the powder is selected from barium titanate.