JPS5852116A - Method and equipment for conveying powdery or granular material with air - Google Patents

Abstract

PURPOSE:To prevent the pulsation of a powdery or granular material and the lag of its control, by detecting the concentration of the powdery or granular material in a mixed flow consisting of air and the material, to control the supplied quantity of the material and thereafter additionally supply the conveying air to the mixed flow to convey the material at a low concentration. CONSTITUTION:Air sent out from an air source 1 is divided to a primary conveyance pipe 3 and an air supply pipe 13 through a ramification pipe 18. The air in the pipe 3 flows to a mixer 4 through a Venturi pipe 8 and a section fitted with a back pressure gauge 9. A pulverized material in a hopper 5 is sent through a feeder 6 into the mixer 4 in which the material is mingled with air. The mingled flow from the mixer 4 reaches a confluence machine 2 through a constricted pipe 11. The revolution speed of an electric motor M is controlled depending on the output of a pressure difference detector 12 which corresponds to the concentration of the pulverized material (the flow rate of the material), so that the quantity of the pulverized material supplied to the mixer 4 is kept constant. In the confluence machine 2, the mingled flow joins air supplied from the pipe 13, so that the concentration of the pulverized material is made low. After that, the mingled flow is conducted to a burner 16 through a pipe 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for pneumatic transportation of powder and granular materials,
In particular, it aims to uniformly transport powder and granules by taking advantage of the advantages of both the high-concentration transport method and the low-concentration transport method.

In the pneumatic transport of powder and granular materials, the technology of quantitatively supplying the powder and granular materials from a storage hopper into transport piping and transporting them pneumatically while maintaining quantitative properties to the final destination has gained increasing importance in recent years. It is increasing.

For example, when pulverized coal is transported pneumatically to be used as fuel in various industrial furnaces such as combustion furnaces, 1III@kilns, and blast furnaces, the amount of pulverized coal supplied to these industrial furnaces is electrically driven, resulting in an excessive supply even for a short period of time. If this happens, not only will there be a loss of heat, but there will also be a risk of an explosion due to the generation of a large amount of carbon oxide, and at the same time, the temperature inside the furnace will rise abnormally, causing damage to equipment, operations, and so on.
This causes various problems in terms of product quality, etc. For these reasons, there is an increasing demand for higher precision in quantitative transport.

As a method for quantitatively supplying such powder or granules to transport piping, a quantitatively decreasing method has recently come into widespread use. This method 14 bt [R grain material hopper and the total weight of the powder material in the hopper can be measured,
This method measures the discharge status of powder and granules in the hopper at a constant sampling period, constantly compares the amount of decrease with a set value, and controls the discharge amount while correcting the error. When the lower limit is reached, a certain amount of powder and granules are discharged and replenished to the umbrella brim, and when the upper limit is reached, the supply is cut off and the control operation is repeated using the method described above.

However, although this method has a relatively high rate of loading, it is expensive because the machine and control system is II line, and it is especially necessary to transport to multiple destinations while controlling the amount of each. In some cases, it is difficult to adopt it due to economic reasons.

On the other hand, there is a method in which the feeder is controlled by detecting the powder or granule concentration or the powder or granule flow rate in the transport piping, and this method can be implemented with simple equipment and is therefore inexpensive. However, the accuracy of the agreement is not sufficient for the following reasons.

In other words, methods for measuring the concentration of powder or granules in air transport piping include methods that utilize the pressure difference before and after the generally used constricted pipe, expansion pipe, straight pipe, or bent pipe, as well as methods that use the pressure difference before and after the flow rate of air transported or Examples include methods that utilize transport air back pressure, methods that utilize the driving current value of a transport air source, or electrical characteristics of transport piping. Such air-based methods for transporting powder and granular materials are broadly classified into high-concentration methods and low-concentration methods, depending on the straining of the powder in the transport air.

In the former high-concentration method, the mixing ratio (weight ratio of transported powder and granular material to transported air) is, for example, S-WSg or higher, and the amount of transported air is small; As a result, powder and granules that are continuously and quantitatively supplied tend to form transport piping metal bodies and are discharged in a pulsating manner at the end of the transport, especially when the transport distance is long or during transport piping. If there are many curved parts or vertically rising parts, the degree of pulsation will become stronger due to factors such as sinking of powder and granules.

On the other hand, in the low concentration transport method, the mixing ratio is, for example, 1 to 3.
41! Because it can transport at a relatively large amount of air and at high speed, it is possible to prevent pulsation of the powder and granules in the transport piping as much as possible. In particular, methods other than those that utilize the pressure difference in short pipes depend on the average particle size of the transportation piping metal body, which not only results in low measurement accuracy but also when the transportation piping is long. Alternatively, if there are many bends or vertically rising sections in the transportation piping, there may be a slight delay.

In this way, when controlling the feeder by measuring the concentration of powder or granular material in the transport pipe, no matter which method is adopted, there is a problem with continuity and quantitative performance at the end of the transport.

Therefore, the purpose of this pricking is to take advantage of the advantages of both the high-concentration transport method, which allows for high concentration measurement at once, and the low-concentration transport method, which has small pulsation, to produce highly continuous and quantitative powder and granule materials. The purpose of the present invention is to provide a pneumatic transportation method and a device for the same, and the gist thereof is to detect the concentration of powder or granule by using a high concentration-overpass method to increase the accuracy of measuring the concentration of powder or granule; “By improving the ability to supply a fixed quantity to the transport pipe, and by supplying additional transport air downstream after measuring the powder and granule concentration, and making most of the transport route a low-concentration transport method, the powder inside the transport pipe can be The purpose is to prevent the occurrence of pulsation of particles.

Next, an embodiment in which the present invention is applied to a system for pneumatically transporting pulverized coal and supplying it to a combustion furnace will be described with reference to the attached w-. Here, the first m and the second Wi are
FIG. 3 is a system diagram of a pneumatic transportation device for powder and granular materials according to an embodiment of the present invention.

In the first stage, a mixing machine consisting of a stationary nozzle (31
4) is interposed, and the pulverized coal cape powder taken out from the pulverized coal hopper 4 by the feeder (6) consisting of a screw feeder is fed to the mixing machine G4> via the gate valve ff). . Entrainment - (The Venturi tube (2) is placed upstream of the Venturi tube) and the back pressure needle ((2) are arranged, and the flow rate of air flowing through the Pentieri tube (8) is -Venturi tube (2) It is detected by an air cap meter connected to the air cap. The Pentieri tube (2) may be replaced with a Pitot tube. There is a constrictor tube section at the threshold between the mixing shaft (4) and the merging machine (2). A powder flow rate measuring device consisting of
Measure the differential pressure before and after the IR tube section using a, and check the throttle tube ■
The concentration of powder in the mixed flow of powder and air flowing inside S#
fi. A signal from the differential pressure detection W@ is inputted to the electric motor board that drives the supply-1, and the powder and granular material in the mixed flow is detected.
Electric wheel feeding machine (2) corresponding to the degree table
The amount of powder and granular material supplied from the mixing machine (2) to the mixing machine (2) is controlled to be constant. At this time, the amount of air transported to the next transport pipe (3) is:
The radius is selected so that the mixing ratio of the mixed flow passing through the IR pipe becomes high concentration. The air 1 field and the merging machine (2) are connected by an air supply pipe that bypasses the venturi pipe (8), the mixing machine (4), and the throttle pipe I,
The pressure of this air supply pipe Q3^ is controlled by a pressure regulating valve a- provided in the middle thereof. The secondary transport pipe (to) connected to the discharge side of the merging machine (2) is connected at its end to an external device such as an m-hook device (2). II indicates the 1afIIA furnace. Further, the concentration of the powder or granular material at the supply part into the transportation pipe of the powder or granular material can also be detected by a back pressure of 11t.

Therefore, from the air 1 field! The discharged air is filled with air that flows into the air supply pipe O through the branch part and the primary transport pipe (air sent into the tank) and the pressure regulating valve.

-The air that enters the next transport pipe (31) is transferred to the Pentieri pipe (31).
Skull and dorsal FE needles (contaminated through the stolen attachment part - (reaching the end).
In the mixing machine (2), the feeder (6
) The powder and granules fed into the mixer (4) are mixed with air, and the mixed flow of the powder and air reaches the merging machine (2) via the throttle pipe (2). - Next transport pipe ( Since the powder concentration is high in pipe (3), if the air flow rate in pipe (3) is kept constant, the pressure loss measured by the pen pressure ll11#M1 device will be equal to the powder concentration and therefore the powder flow rate. Therefore, by controlling the degree of transfer of the electric motor using the signal sent from the differential pressure detection (2), the amount of powder and granular material supplied to the mixing machine (2) can be kept constant. The mixed flow that has reached the merging machine (2) in this way flows together with the air supplied to the merging machine (2) from the air supply pipe 0, resulting in a low concentration and a secondary Escape from the transportation piping,
Aim device 2).

In the second embodiment shown in 11!2-, the air source is high-pressure air *a*> that feeds air into the primary transportation pipe CIX),
Low pressure air solder (1b) that introduces air into the air supply pipe 03.
), and the mixing machine @Gin is composed of an ejector. In this case, a detector α2 is installed as a particle storm leakage device that uses the differential pressure before and after the mixing Ii & @Gin. has been done. In addition, an orifice is provided upstream of the mixing machine (4x), and the differential pressure generated by this orifice is detected by a differential pressure detector, and the transport air flow control valve is operated according to the detected amount. Adjust the amount of air inflow to the next transport pipe G~ to a constant value. Furthermore, the entire hopper is supported by a weighing machine (2), and the granulation of the powder in the hopper is emitted by IR. Therefore, in this implementation, the high-pressure air source α is sent out. The air is quantified by the flow control valve (2) operated by the pressure from the differential pressure detection sea, flows into the mixer @X, and is supplied from the hopper SX) by a 1-# lid feeder, etc. It mixes with the powder and granules carried out by the flow and reaches the converging machine a. In the mixing machine (4 m), a considerable amount of air energy is consumed to accelerate the supplied powder and granular material, and this is rewarded as differential pressure. % is proportional to the mixing ratio, so by measuring the differential pressure after the input machine, it is possible to measure the powder and granule concentration with good accuracy. Since there is little transport and the residence time in the measuring device is short, the weight of the powder ai can be measured. The amount of powder and granular material supplied and taken out from the powder and granular material hopper 7 (SN) is maintained constant by automatic control.

In this way, it arrives at the merge plane c2. The powder concentration of the previous mixed flow is kept high, but the confluence - a! Ride! , supplementary air sent from low pressure air source αb) and mixing machine (4x)
It merges with the mixed flow that flows out further, resulting in a low concentration. In this way, the mixed flow, which has a low degree of resolution, flows back through the secondary transport pipe (15x) to 31! Sardines are sent to a kiln, etc.

In addition, the weighing machine (2) attached to the hopper (5 m) was used to measure the actual amount of powder and granules discharged from the hopper, and the differential pressure and detection -02 gradient were measured. By correcting the Oka iwm value by comparing it with the measured value of the flow rate, a certain degree of accuracy can be improved. In addition, in this example, the air source is divided into high pressure and low pressure, so the driving power of the pneumatic machine can be minimized for the bladder.

In these methods, methods, and devices, the concentration of powder and granules in the primary transportation piping should be higher than that in the secondary transportation piping, and the concentration of powder and granules in the secondary transportation piping should be higher than that in the secondary transportation piping. Alternatively, the means for measuring the flow rate of powder or granular material is not limited. In addition, since the primary transport arrangement using the high concentration transport method requires only a long pipe length, it is possible to achieve high-speed transport from the viewpoint of transport air pressure, and therefore there is less pulsation of the powder inside the pipe, but - In order to make the flow of powder and granules smoother in the secondary transport pipe, the secondary transport pipe is arranged to be inclined diagonally downward towards the downstream side.
Alternatively, a rising pipe can be used to increase the measured differential pressure. Further, it is desirable to provide the differential pressure transmitter with a buffer for averaging short-period behavior.

As described above, the present invention detects the concentration of powder or granular material under a high-concentration transport form with a short piping length, replenishes transport air after detecting the concentration, and converts most of the transport route into a low-concentration transport method. Because it is a natural material, the differential pressure for concentration detection is large, and the measurement accuracy of powder and granule concentration is improved, and pulsation of powder and granule does not occur in the transportation pipe, and the same layer with control is also improved. Moreover, after the concentration is detected, it relies on a low-concentration transportation method with a relatively large volume of air, so it can be transported at high speed, and pulsation of powder and granules can be prevented as much as possible. Obviously, it has the advantage of being able to be measured and controlled continuously and being inexpensive.

[Brief explanation of the drawing]

Figure 111 and Figure q and Figure 2 are all systems of a pneumatic transportation device for powder and granular materials according to one embodiment of the present invention. (Explanation of symbols) 1, 1 turtle, lb-air source, 399. is, 15
! -Transport piping 4, 4X-, man and aircraft! ! , 51L-
Powder hopper a, @x--supplier, 2.
2x - Synthetic fiber machine 12, 12 - Differential pressure detection 11 (device for detecting the concentration of powder and granular material), 13.13m -
Air supply piping. Patent applicant: Kanesha Co., Ltd., Kobe Steel, Ltd., Mr. San, Patent attorney: Takeo Honjo

Claims (1)

[Scope of Claims] 1. A method for pneumatic transportation of powder and granular materials, in which the powder and granular materials are supplied to an air flow flowing through a transportation pipe to form a mixed flow of air and the powder and granular materials, and the powder and granular materials are transported, The powder and granule concentration in the mixed flow is detected near the supply part into the powder and granule transportation piping, and the powder and granule supply amount is summed, and the waste mixed flow that has passed through the powder and granule concentration detection part is A method for pneumatically transporting powder and granules by supplying additional transport air to reduce the concentration of the powder and granules, and then transporting the powder and granules as a mixed flow with a low concentration. 2. The pneumatic transportation method according to claim 1, wherein the concentration of the powder or granule is detected by the pressure generated by the acceleration energy of the powder or granule when the m-particle is mixed into air. 3. A feeder that takes out powder and granules from a powder hopper is connected to a mixing machine installed in the middle of a transport pipe connected to an air source, and the powder and granules are mixed into the transport air in the transport pipe for pneumatic transport. In a pneumatic transportation device for powder and granular materials, a merging machine is arranged downstream of the mixing machine, and an air supply pipe whose one end is connected to an air source is connected to the merging machine, and the powder and granular material downstream from the merging machine is A pneumatic transport device for powder and granular material, characterized in that the powder and granular material are transported while being reduced in concentration, and a device for detecting the concentration of the powder and granular material is provided in the transportation piping upstream of the merging machine. 4. Claim 3, which uses a differential pressure detector that detects the differential pressure before and after the mixing machine as a device for detecting the amount of powder or granular material.
Pneumatic conveyance device as described in Section.