JPS60129621A - Measurement of flow rate of powdery granule in solid/gas phase flow - Google Patents

Abstract

PURPOSE:To realize higher reliability, by calculating existing informations of assumed correcting factors by comparing total sum of flow of a powdery granule in a branched tube and decrement of a storage container and by obtaining an actual flow rate of the powdery granule basing upon said informations, carrier gas informations and pressure informations, etc. CONSTITUTION:Flow meters 6a-6c and manometers 8a-8c installed in gas-flow sections 3a1-3c1, manometers 9a-9c and a computer 10 in double-flow sections 3a2-3c2 respectively are connected through flow rate transmitters 7a-7c, pressure transmitters 11a-11c, 12a-12c respectively. The computer 10 calculates the existing informations of assumed correcting factors by the total sum of flow rate of the powdery granule in the branched tubes 3a-3c and decrement of the storage container 1 and from the existing informations of correcting factors thus calculated, flow rate informations of carrier gas 4 and pressure information in process of transportation of the powdery granule, the existing flows of the powderous material in the individual branched tubes 3a-3c are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has the following features: 1. A state in which various powders and granules are dispersed in a gas and flowing, that is, a solid-gas two-phase flow (hereinafter sometimes simply referred to as two-phase flow). The present invention relates to a method that can accurately measure the flow rate, particularly the flow rate of powder and granular material in a branch pipe for dispensing.

BACKGROUND ART As a method of transporting powder and granular materials (hereinafter simply referred to as powder) from a storage container to another location, a transportation method using pressurized air current is widely used. In this case, the powder flow rate can be estimated by measuring the weight loss of the powder over a certain period of time in the storage container using a strain gauge installed in the storage container, and calculating the average flow rate per unit time. It is normal to have Although this type of air flow transport method is very effective as a means of distribution transport, the above-mentioned method for measuring powder and body flow rates requires individual measurement of the transport volume of each distribution branch pipe.

There is no way to do it. For example, when injecting coal into a blast furnace, 2.5 bottles are taken from 2.1 storage containers.

In the process of distributing and transporting pulverized coal through each branch pipe to the handle 9, it is necessary to determine the overall injection amount and the level of each coal.

Although it is possible to know the uniform injection amount, it is not possible to know the actual amount of pulverized coal fed from each tuyere. I can't figure it out. For this reason, techniques are being developed that can measure the powder flow rate for each branch pipe. For example, a method of installing a venturi in a branch pipe and measuring the differential pressure before and after it and calculating the powder flow rate from the measurement of capacitance, or 2.
An ultrasonic Doppler type that measures the flow velocity by projecting ultrasonic waves onto powder particles transported in a phase flow, or a thermal flowmeter that measures the flow rate by detecting the heat loss due to the flow by temperature measurement, etc., have been proposed. . However, these known methods have problems in terms of measurement accuracy and cannot be said to be satisfactory.

In a two-phase flow, there are many parameters such as particle size, specific gravity, solid-gas ratio, gas flow rate, and pressure, and the properties of the flow change in a complex manner. This is due to the unique circumstances of solid-gas two-phase flow, such as the fact that it is extremely difficult to reduce the flow rate by converting into solid-gas flow.

A method has also been proposed in which a flow rate detection member, such as a Coriolis flowmeter, is placed directly in the two-phase flow path, but this method cannot avoid wear of the detection member due to powder collisions, and furthermore, the detection There is also the problem that the flow is obstructed by the members, making it easy for pipe clogging to occur.

Under these circumstances, we focused on the 6-fluctuation property of two-phase flow and measured unique signals (such as capacitance) between two points, which are unnecessary for powder to move between two points. This is a correlation detection method in which the powder flow velocity is measured by measuring time using a correlation method, and the powder flow rate is calculated by multiplying the powder density obtained by separate capacitance measurement. A new proposal has been made.

A flow meter that adopts this correlated product method has practical reliability accuracy and can be measured even in the presence of pulsation, external turbulence, etc., so it is thought that it can become a promising method in the future. However, the unit price of the flowmeter has to be significantly higher due to the sophisticated built-in calculation circuit. Therefore, if such an expensive flow meter is attached to each of about 25 branch pipes as in the above-mentioned blast furnace pulverized coal injection, the cost of the pulverized coal injection equipment will be enormous and it will be economically disadvantageous.

The present inventors have solved all of these problems, that is, a flow measurement method that does not obstruct the flow of the two-phase flow and does not cause problems such as wear of the detection member, and is capable of distributing and transporting the two-phase flow. Various studies have been carried out in an attempt to establish a method that can measure the powder flow rate in each branch pipe with sufficient practical reliability and accuracy and in an economically advantageous manner. The present invention was completed as a result of such research, and its configuration not only measures the amount of powder reduced in the storage container, but also collects carrier gas flow rate information obtained under the same measurement conditions for each branch pipe. Calculate the powder flow rate in each branch pipe from the pressure information, the pressure information in each branch pipe during powder transportation, and the tentative correction coefficient, and then calculate the sum of these powder flow rates in the branch pipe and the amount of decrease in the storage container mentioned above. For comparison, the current information of the above assumed correction coefficient is calculated, and the current information of the calculated correction coefficient, the above carrier gas flow rate information, the same pressure information, and the pressure information during powder transportation in each branch pipe are calculated. The main point is to consider the current actual powder flow rate □.

The configuration and effects of the present invention will be explained below with reference to the drawings.

FIG. 1 is a schematic explanatory diagram of the present invention, and for ease of understanding, the powder 2 distributed and supplied from one storage container 1 to three branch pipes 3a to 3c is divided into three branch pipes 3a to 3c. Each branch pipe 3a to 3 when airflow is transported by carrier gas 4 flowing through 3c
The case of measuring the flow rate of powder '2 in C will be explained.

The storage container 1 is filled with the powder 2, and its weight can be measured by the weighing scale 5 in this filled state.The measured value is sent to the calculator 10 as a signal. Sent. Branch pipes 3-4c are connected to the powder distribution and supply chutes 1a to 1c disposed at the lower part of the storage container 1, and each branch pipe 3-4c is connected to the powder 2 and carrier gas '4. The branch pipes 3a to 3c are airflow sections 3al to 3, respectively.
c1 and two-phase flow sections 3ai to 3cl are formed. The pipe diameters of the branch pipes 3a to 3c are the same, and the arrows indicate the flow direction. Further, 6a to 6c and 8a to 8c are flow gauges and pressure gauges provided in each of the air flow sections 3al to 3c, and 9a
~9c is a pressure gauge provided in each of the two-phase flow sections 3a and ~3cl, and the pressure gauges 9a~9c are at the confluence point (generally called a mix tea) with each powder distribution/supply shoe) 1a~1c. The fitting is located equidistant from the pipe to which it is connected. These flowmeters 6a-6C2 pressure gauges 8a-8C29a-9
C and the computing unit 10 are connected via flow rate transmitters 7a to 7c+pressure transmitters 11a to 11C and 212a to 12C, respectively. That is, the flow rates F, ~F, and pressures P1 ~ of the carrier gas flowing through each of the branch pipes 3a to 3c are determined by the flow rate transmitters 78, respectively.
7C and pressure transmitters 11a to 11c as signals to the computing unit 10, and the pressure Pal to Ps during powder transportation under constant measurement conditions, the signals are input to the pressure transmitters 12a to 12a to 12c.
The signal is input to the arithmetic unit 10 through 2c.

In the arithmetic unit 10, the following calculations are automatically performed by inputting the various signals mentioned above. To explain along the calculation procedure, first, the weight flow rate (
(hereinafter simply referred to as flow rate) is Wlt W2 + Wa
Then, the sum of these flow rates (W1+W2+W,)
is equal to the weight of the powder flowing out from the storage container 1, that is, the reduced weight dw/dt of the entire powder-containing storage container 1 detected by the weighing scale 5, but the current actual measured value of this reduced weight is always equal to Since it has been input, the current actual measured value of (W 1 + Wt + WB) is shown below (1)
Calculated from the formula.

w, +w, 10W, -d haiku t...(1)
On the other hand, for w, tw, tw, each two-phase flow section 3a2~
Considering that the pressure drop at 3c was measured under constant measurement conditions (i.e., the same conditions for tube length, tube diameter, powder physical properties, etc.), the corrections used in the following equations (2) to (4) 1 to K for the coefficient
m (correction coefficient determined by opening cross-sectional area and other transportation conditions) can be replaced by a certain temporary unknown K (hereinafter referred to as common coefficient), and as a result, W, +W, +W, can be expressed as in equation (5) below. It is calculated as follows.

) Next, a comparison operation between the above equations (1) and (5) is performed,
According to the following formula (6), the current effective value (as a correction coefficient,
The most suitable actual value for the current situation) is calculated.

t By applying the value of Shu calculated in this way to 1 (2) to (4)
The current actual value of 1' is found.・1・.

Any type of pressure gauge may be used in the above-mentioned powder measurement. The pressure gauge may be arranged so that its detection portion penetrates the tube wall of each of the two-phase flow sections 9a to 9C and communicates with the inside of the tube. In this type of pressure guiding method, the flow of the two-phase flow can be maintained sufficiently smooth compared to the conventional direct loading method in which the entire detection member is placed in each of the two-phase flow sections 9a to 9C. It becomes possible to do so. Since only one pressure permissible point is provided in each two-phase flow section 98 to 9C,
The equipment is extremely simple compared to the case where the above-mentioned correlation detection flowmeter or the like is provided.

The above-mentioned embodiments are representative examples of the present invention, and the present invention is not limited in nature. For example, the calculation method was changed in line with the above-mentioned purpose, and the type of information obtained and the information obtained were changed accordingly. It is also possible to change the method of calculation, and even if the above calculation procedure is adopted, the number of branch pipes, pipe diameter, pressure drop measurement position and interval length, etc., each flow meter, pressure gauge, Appropriate design changes to the type and arrangement of the weight needles, etc. of the storage container fall within the technical scope of the present invention.

Since the present invention is constructed as described above, when the powder is distributed and supplied from a storage container to a plurality of branch pipes and then transported by pneumatic flow, the flow rate in each branch pipe can be easily and economically determined with sufficient practical and reliable accuracy. It has become possible to measure this effectively. As a result, it became possible to easily manage the powder flow rate accurately for each branch pipe.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the method of the present invention. 1...Storage container 2...Powder 3a-3c...Branch pipe 3al-3cl...Air flow part 3a! ~3c! ...Two-phase flow section 4...Carrier gas 5...Weight meter 6a-6c...Flowmeter 8a-8c
, 9a-9c...Pressure gauge 10...Calculator 7a-'7
c...Flow rate transmitter 11a-11c*12r-12c...Pressure transmitter Applicant Kobe Steel, Ltd.

Claims (1)

[Claims] (1) Powder particles distributed and supplied from a storage container to a plurality of branch pipes are air-flow transported by 5. a carrier gas flowing through each branch pipe. In measurement method 4, the flow rate of powder and granular material in each branch pipe during measurement, the amount of powder reduction in the storage container is calculated, and the carrier gas flow rate information and pressure information obtained under the same measurement *, During transportation of powder and granular material 9 Each: Calculate the powder flow rate in each branch pipe from the pressure information in the branch pipe and the assumed correction coefficient.1. Next, by comparing the sum of the powder flow rates in these branch pipes and the amount of powder reduction in the storage container, the current information of the above assumed correction coefficient is calculated, and the current information of the calculated correction coefficient and the above carrier, yagasu are calculated. Solid air 2 characterized by calculating the current actual flow and amount of powder and granular material in each branch and pipe from flow chapter information, same pressure information, powder and granular material being transported 9, and pressure information in each branch pipe.
．． A method for measuring the flow rate of powder and granular materials in phase flow.