JPH07117846A - Plug type pneumatic conveying method for powder - Google Patents

Abstract

PURPOSE:To perform mass transportation of powder, prevent the deterioration of quality and reduce wear in a piping system as far as possible by partially lapping the valve opening/closing timing of pressurized gas over that of fluidized gas in plug type pneumatic conveying. CONSTITUTION:When powder such as slack coal is conveyed by means of plug type pneumatic conveying, opening/closing timing of an air knife gas supply valve V3 4 producing a plug dose not alternate with that of a tank pressurized gas supply valve V1 2 and a powder fluidized gas supply valve V2 3, but partially lapped over that of them, so that all of the valves are opened at the same time when each valve is switched. In this way, a mass discharge of the powder just after switching to the tank pressurized gas supply valve V1 2 and the powder fluidized gas supply valve V2 3 is suppressed, so that gas can be blown into a lump of powder fed to piping under a high density condition, and permeability is improved, and consequently, stable plug type pneumatic conveying is accomplished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes stable and continuous plug transport even when the properties of powder, for example, pulverized coal, change, and also relates to changes in the remaining amount of pulverized coal in the cutting tank. The present invention relates to a method of transporting a plug of powder, which can be flexibly dealt with.

In the following, as "powder",
The present invention will be described by taking pulverized coal, that is, pulverized coal as an example.

[0003]

2. Description of the Related Art For transporting granular materials such as unloading coal from a cargo ship, conventionally, equipment such as an unloader, a belt conveyer, etc., which is transported to the atmosphere and has a mechanical operation part, has been used. It was In such an open-type transportation facility, not only are environmental problems such as dust generation serious, but maintenance of mechanical operating parts is also complicated due to dust generation.

As measures against such dust problems, transportation by a pipe conveyor or pipeline transportation in which the transported object is not an open system has been proposed. In the case of a pipe conveyor, there is little freedom in the layout of the transportation line, and especially in the vertically rising part, it is necessary not only to transfer to a vertically transportable equipment such as a bucket conveyor, but also dust collection equipment in the replacement part. Therefore, the increase in equipment cost cannot be avoided.

On the other hand, pipeline transportation, for example, Japanese Patent Publication Sho
In the method disclosed in Japanese Patent No. 53-23321, since the transportation system can be a completely closed system, from the viewpoint of dust prevention or the avoidance of impurities and foreign substances from the outside,
It is used not only in the steel industry but also in various industrial fields.

In the case of suction type air flow transportation using such a pipeline, the flow velocity is usually 15 to 30 m / s and the solid-gas ratio is
About 10 floating transportations are used. In the case of this transportation method, it is difficult to mass-transport because the solid-gas ratio is relatively small, and a large amount of carrier gas is required to secure the flow velocity of the granular material to be transported to a certain extent, which increases the transportation cost. At the same time, the solid-gas separation device, the bag filter, etc. are increased in size and the equipment cost is increased. In addition, since the transportation speed is high, the particles themselves are destroyed by piping or collision between particles, and classified due to the difference in particle size and density. Problems such as component fluctuations after sending due to segregation occur, and have a great impact on the technical evaluation of the process.

Further, in the floating transportation as described above, when the hardness of the granular material is high, the transportation facility may be abruptly stopped due to the abrasion of the transportation pipe due to the granular material.
It is known that the wear of pipes due to particles is proportional to the particle velocity to the power of 2-3. Certainly, lowering the particle velocity is effective in reducing pipe wear due to particles, but if the particle velocity is low, the possibility of pipe clogging increases and stable operation of equipment becomes difficult.

Moreover, in the above-mentioned suction type floating transportation, since only atmospheric pressure can be used as the transportation pressure, mass transportation is difficult. Further, in floating transportation, it is necessary to suspend the particles to be transported in a carrier gas in a pipe, so it is difficult to transport particles with a high density and particles with a large particle diameter, so increase the amount of carrier gas. There are restrictions on the applicable particles.

[0009] As a measure against the problems of low solid-gas ratio and wear of pipes, which is involved in such floating transportation, application of plug transportation, which is one of air current transportation for realizing high-concentration low-velocity transportation, has been proposed. For example, the method proposed in JP-A-57-117415. However, in that case, the conditions for forming a stable plug and establishing transportation differ depending on the properties of the powder or the transportation conditions, and have not been widely used.

That is, in the method of blowing a carrier gas into such a transportation pipe to form a plug, it is possible to make a plug in the case of fine powder having a narrow particle size distribution. This is because when transporting coarse-grained coal having a wide particle size distribution to be supplied to the crushing equipment, the air permeability becomes too poor to make a plug.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art and to provide a stable method for plug transport of powder regardless of particle properties or transport conditions. Is.

More specifically, the object of the present invention is to enable mass transportation in a plug transportation system of pulverized coal, to improve efficiency, and even when high-speed transportation is performed, deterioration of powder quality is not observed. The purpose of the present invention is to provide a pulverized coal plug transport system that minimizes the wear of the delivery pipe system.

[0013]

The inventors of the present invention have conducted various studies in order to solve such problems, and as a result,
The present invention has been completed, knowing that the above-mentioned problems of the prior art can be solved by partially overlapping the valve opening / closing timings of the pressurized gas and the fluidizing gas in the plug transportation.

Here, the gist of the present invention is that in a method of transporting powder by plug transport, an air knife gas supply valve and a tank pressurized gas and powder fluidizing gas supply valve are alternately opened / closed. Upon closing, the plug opening method of the powder is characterized in that the valve opening / closing timing is overlapped so that both valves are opened at the same time when the valves are switched.

In the present invention, the lap time of the valve opening / closing timing may be changed during transportation according to the pressure difference between the tank pressure and the pipe pressure. As described above, according to the present invention, a gas supply valve for an air knife for generating a plug in a facility for transporting powder particles by plug transportation,
Instead of opening / closing the tank pressurizing gas / powder fluidizing gas supply valves alternately, by partially wrapping the valve opening / closing timing so that both are opened simultaneously when the valves are switched, the particle size distribution, The plug transportation can be stably carried out regardless of the transportation conditions such as the shape of the powder, the particle properties such as the water content of the powder, the transport tank pressure, and the carrier gas amount.

[0016]

1 is a schematic explanatory view of a plug transportation facility for carrying out the present invention. In the figure, the transport tank 1 has three gas supply ports, 2 is a tank pressurized gas supply valve (V ₁ ),
3 is a powder fluidizing gas supply valve (V ₂ ), and 4 is an air knife gas supply valve (V ₃ ). The powder fluidizing gas is introduced into the tank through the dispersion plate 5 provided at the lower part of the transportation tank 1. The air knife gas is introduced into the transportation pipe 7 through the air knife 6 installed at the exit portion of the transportation tank,
By opening and closing these gas supply valves 2, 3, 4
A plug of powder is generated in the transportation pipe 7.

The powder plug passes through the transportation pipe 7, is solid-air separated by a cyclone 8 installed above the receiver tank 9, and is supplied into the tank. FIG. 2 explains the timing of valve opening / closing at this time. In the conventional method, (V ₁ , V ₂ opening time) / (V ₃ opening time) = 1 second / 1 second, and the same. However, in the present invention, the opening time of each valve is overlapped as shown. By the way, if the discharge amount of powdery particles from the transport tank is the same powder,
Determined by the difference between the transport tank internal pressure and the pipe pressure.

In the conventional plug transport equipment,
When the tank pressurized gas / powder fluidizing gas is supplied, the powder particles are supplied from the transportation tank to the transportation pipe, and the powder is not supplied when the air knife gas is supplied. That is, the air knife gas supply valve and the tank pressurized gas and powder fluidizing gas supply valve are alternately opened and closed. Therefore, when switching from the air knife gas supply valve to the tank pressurized gas / powder fluidizing gas supply valve, the powder plug moves to a position away from the transport tank, and the internal pressure of the pipe is low, so the powder from the transport tank A large amount of particles and a high density are supplied to the pipe.

The powder plug thus produced is
The air permeability is poor and the resistance when moving in the pipe becomes very large. Therefore, the moving speed of the powder plug decreases and the internal pressure of the pipe also increases. Then, the generation of the next powder plug is hindered, so that a short plug is generated. However, since this powder plug is easy to move, the next powder plug becomes large.

As described above, since the size of the powder plug greatly changes each time the powder plug is generated, a large change in the transport amount or a blockage of the pipe may be caused. Stable operation is difficult. Such a phenomenon is affected by the particle size distribution, the shape of the powder, the particle properties such as the water content of the powder, or the transport conditions such as the transport tank pressure and the carrier gas amount, and the friction resistance between the plug and the pipe is large. It becomes a problem.

Therefore, according to the present invention, an air knife gas supply valve and a tank pressurizing gas / powder fluidizing gas supply valve for generating a plug when the powder such as pulverized coal is transported by plug transportation. Instead of opening / closing alternately, the valve opening / closing timings are partially overlapped so that both valves are opened simultaneously when the valves are switched. By adopting such a configuration, it is possible to prevent a large amount of powder from being discharged immediately after switching to the tank pressurized gas / powder fluidizing gas supply valve, and to supply the powder to the pipe in a high density state. Blow gas into the mass to improve air permeability and realize stable plug transportation.

The lap time between the air knife gas supply valve and the tank pressurizing gas / powder fluidizing gas supply valve in the present invention is not particularly limited, but in general, the tank pressurizing gas
0.1 to 0.5 regardless of the opening time of the powder flow gas supply valve
It is preferable to occupy seconds, which also depends on powder properties and transportation conditions.

Further, by changing the lap time of the valve opening / closing timing during transportation based on the transportation state such as the remaining amount in the transportation tank and the amount of powder transportation, the cutting amount can be stabilized or the rapid cutting amount can be controlled. Adjustments can be made to achieve stable plug transportation.

That is, when the tank pressurized gas supply valve and the air knife gas supply valve are opened, the powder supply amount can be reduced by increasing the pressure at the tank outlet. Therefore, the amount of powder cut out from the pressure tank can be adjusted by detecting the differential pressure between the tank pressure and the pipe pressure and controlling the lap time based on the differential pressure.

FIG. 3 is a schematic explanatory view of an apparatus used when the lap time of the plug generation valve is changed during transportation. Using the device shown in the figure, a pressure measuring device 10 is installed in the transport tank 1, and a pressure measuring device 11 is provided downstream of the air knife 6.
The controller 12 can be used to adjust the valve opening / closing time so that these pressure differences are constant.

As described above, according to the present invention, as compared with the method of controlling the tank pressure which is performed in the usual air flow transportation method,
It is possible to quickly control the powder transportation amount and prevent pipe clogging. Next, the operation of the present invention will be described more specifically with reference to Examples.

[0027]

【Example】

(Example 1) In this example, the apparatus of FIG. 1 is used to carry out plug transportation, and the lap time of valve opening / closing at that time is as shown in FIG. 2 (V ₁ , V ₂ opening time) / (V ₃ opening). Time) = 1 sec / 1.3 sec and 1 sec / 1.2 sec, and the lap time was 0.3 sec and 0.2 sec. Table 1 shows the results of the powder transport test by the test device of FIGS. 1 and 2.

As can be seen from these results, in the present invention, the solid-gas ratio is increased from 45 to 70 to 75 and the transportation pressure is reduced, as compared with the ordinary plug transportation as in the conventional example without wrapping. did. Further, since the carrier gas amount is small, the amount of dust discharged from the cyclone 8 which is the solid-gas separation device is also reduced.

Table 2 shows the results of transporting and charging coal into the coke oven by pneumatic transportation when the type of coal was changed in the coke oven by the same method as described above. Since the transportability of coal differs depending on the brand of coal and the amount of water, pipe blocking may occur when the formulation of coal was changed in the conventional example, but in the case of the present invention, such disturbance is caused. Was less affected.

In this embodiment, the tank pressurizing gas supply valve V ₁ and the powder fluidizing gas supply valve V ₂ are operated synchronously,
On the other hand, although the plug was generated by the opening / closing operation with the air knife gas supply valve V _3, it is necessary to have both the tank pressurized gas supply valve V ₁ and the powder fluidizing gas supply valve V _{2 in} order to make the plug. Either one or the other may be used.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

As described above, when the present invention is applied to equipment for transporting various powders by plug transport, the plug transport with a high solid-gas ratio can be stably carried out. Even when the characteristics of the powder to be transported inside are changed, it is possible to flexibly cope with the reduction of the transportation amount and the clogging of the pipe.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an airflow transportation test device used in an example.

FIG. 2 is a schematic explanatory view showing the principle of the plug transportation method used in the present invention in comparison with that of the conventional method.

FIG. 3 is a schematic explanatory view of a modified example of the airflow transportation test device of FIG.

[Explanation of symbols]

1: Transport tank, 7: Transport pipe, 2: Tank pressurized gas supply valve, 8: Cyclone, 3: Powder flow rate gas supply valve, 9:
Receiver tank, 4: Air knife gas supply valve,
10: Pressure measuring device 5: Dispersion plate, 11: Pressure measuring device 6: Air knife, 12: Controller

Claims (1)

[Claims] 1. A method for transporting powder by plug transport, wherein when an air knife gas supply valve and a tank pressurized gas and powder fluidizing gas supply valve are alternately opened / closed, both of them are switched when the valves are switched. A method for transporting a plug of powder, characterized in that the valve opening / closing timing is overlapped so that the two are opened at the same time.