JPH0134898B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a method for defoaming a foamed slurry, and more specifically, to a method for defoaming a foamed slurry, and more specifically, a method for defoaming a foamed slurry. This invention relates to a method for removing air bubbles from a foam slurry when the foam slurry is transported by pipeline and then shipped.

BACKGROUND ART AND PROBLEMS Generally, coal is transported by land from a coal producing area to a shipping port, and then transported by sea from the port by ship. Recently, in order to lower the transportation cost of land transportation and to streamline loading operations at ports,
Increasingly, granular coal is dispersed in water in coal producing areas to make coal slurry, which is then transported via pipeline to a shipping port and then loaded onto a carrier vessel in slurry form via pipeline. There is. According to this method, when loading coal, the ship does not have to be directly attached to the quay.
It is very advantageous to be able to load automatically using a floating hose or the like connected to a shore facility via a single point mooring buoy or the like. When transporting coal slurry by pipeline, it is desirable to increase the coal weight concentration (the weight ratio of coal to the entire slurry) as much as possible in order to increase the transport efficiency of coal. However, when the weight concentration of coal in the slurry increases, the viscosity of the slurry itself increases and its fluidity decreases, which increases the transportation power and, in some cases, makes pipeline transportation by pump impossible. For this reason, the weight concentration of coal in ordinary coal slurry that is dispersed in water and transported by pipeline is limited to 40 to 50% by weight, and the slurry contains approximately 50 to 60% by weight of water. As a result, the transport efficiency of coal decreases accordingly, and dehydration is required after transport.

Therefore, the present applicant created a highly concentrated foam slurry by mixing a foamed fluid obtained by foaming a mixture of a blowing agent and water with powder and granules under atmospheric pressure, and placed the mixture of foaming agent and water in a high-pressure container. The high-pressure foamed fluid foamed with the above-mentioned foam slurry is mixed in a high-pressure container to create a high-pressure, high-concentration foam slurry that is fluid even under high pressure, and this high-pressure foam slurry is sent through a pipeline. We proposed a method for transporting powder and granular materials. According to this method, the fluidity of the slurry can be improved by lowering the volume concentration without reducing the weight concentration of the particulate matter in the slurry.
Therefore, the weight concentration of the particulate matter in the slurry can be made very high to increase the transport efficiency, and there is no need to dehydrate the slurry after transport. However, if the aerated slurry transported in this way is loaded directly into a ship's hold, the weight concentration of the powder and granules in the slurry is high, but the volume concentration is small, so the loading efficiency of the powder and granules in the hold decreases. . The same applies when the aerated slurry is placed in a place other than the ship's hold after being transported.

The purpose of this invention is to solve the above problems, to efficiently remove air bubbles from the foamed slurry transported by a pipeline, and to defoam the foamed slurry, which can be shipped with a high volume concentration of powder and granules. The purpose is to provide a method.

Means for Solving the Problems The method of defoaming a foamed slurry according to the present invention involves transporting a foamed slurry, which is a mixture of a foamed fluid made from a mixture of a foaming agent and water, and powder by a pipeline, and then shipping it. In doing so, the foam slurry after transportation is sprayed onto a screen having multiple openings through which fluid can freely pass through to remove air bubbles and drop, and the foam slurry that has fallen from the screen is stirred to further remove air bubbles. It is characterized by:

Function When a foam slurry is sprayed onto a screen having a plurality of openings, the air bubbles are separated by the impact force, and the slurry after the air bubbles have been separated falls under its own weight. The fallen slurry is agitated, which further removes air bubbles.

Since the screen has multiple openings that allow fluid to freely pass through, the liquid contained in the bubbles will not become clogged and cause clogging, and the separated air bubbles and the bubble slurry will be separated. A portion of the entrained airflow can be vented to the opposite side of the screen to enhance the defoaming effect.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows coal shipping equipment at a shipping port, and this equipment is roughly divided into a foam slurry generation device 1 installed on land, a solid-gas separation device 3 installed on a coal carrier 2, and a space between them. It is composed of a bubble slurry transport pipe 4 arranged in a.

In the mixing tank 5 of the bubble slurry generation device 1,
The foaming agent and water that are continuously supplied from the foaming agent tank 6 and the water tank 7 are mixed, and this mixed liquid is continuously sent to the foaming tank 8 and the high-pressure foaming device 9. The foaming tank 8 is equipped with an air blowing pipe 10 and an agitator 11, and the mixture of foaming agent and water is completely aerated in the tank 8 to become a bubble fluid, which is continuously supplied to the coal mixer 12. Sent. Examples of the blowing agent include a blowing agent made of a nonionic surfactant, a blowing agent made of a sulfonate type anionic surfactant, and a blowing agent made of a sulfate salt type anionic surfactant. On the other hand, granular coal is quantitatively fed into the coal mixer 12, and the bubble fluid and coal are mixed to create a highly fluid and highly concentrated bubble slurry. Coal is transported from a coal production area to a shipping port by appropriate means, and is pulverized as appropriate before or after this transportation. For example, when coal is turned into a water slurry at a coal producing area and transported as a slurry through a water slurry transport pipe 13, the coal powder is appropriately dehydrated by a centrifugal separator 14 and supplied to a coal mixer 12.

The bubble fluid that has entered the coal mixer 12 is mixed with coal and moves from left to right in FIG.
The concentration of coal gradually increases as you move to the right. The foam slurry that comes out of the coal mixer 12 has a coal weight concentration of 70 to 80% and a volume concentration of 50%.
It becomes a soft cream with high fluidity and is sent to the refoaming device 15. By creating a large amount of small bubbles and mixing them with relatively small coal particles, a foam slurry is created in which the coal particles are dispersed on the surface of the bubbles due to the surface tension of the bubbles. In this foam slurry, the volume of the bubbles is large, so the volume concentration of coal is small, and the weight of the bubbles is extremely small, and the amount of water used to create the bubbles is very small, so the weight concentration of coal is high. In general, the fluidity of a slurry depends on the volume concentration of solids in the slurry, and when the volume concentration of solids becomes smaller than a certain value determined by the properties of the solid, the fluidity of the slurry suddenly changes. becomes larger. In addition, since the volume concentration of coal in the foamed slurry made as described above is small, the fluidity of the slurry is high and is relatively similar to that when only the foam is flowed, making it easy to transport by pipeline. In this way, by using a foamed fluid instead of water, it is possible to significantly reduce the volume concentration without reducing the weight concentration of coal, making it possible to create a highly concentrated slurry with sufficient fluidity. can.

It is said that transport of ordinary coal/water slurry becomes extremely difficult when the volume concentration exceeds 50%. This is because as the volume concentration increases, the pipe becomes close to being tightly packed with coal particles, and the chances of the particles coming into contact with each other increase, resulting in an increase in the viscosity of the slurry. It is from. That is, the viscosity of the slurry increases rapidly in proportion to the volumetric concentration of coal. Now, if we consider a foamed coal slurry that is a mixture of soft cream-like foam and fine coal particles (small particles that can be supported by the surface tension of the foam), if the volume ratios of coal and air bubbles are the same, then there will be almost no particles. The contact conditions are also the same, and slurries with approximately the same viscosity can be made. (The viscosity properties are different due to the influence of the viscosity of the bubbles.) However, since the amount of moisture (water and additives) that forms these bubbles is very small,
The volume ratio of coal to water and coal can be increased compared to the apparent clean water slurry, and transportation is possible even when the volume concentration is 50% or more. In experiments, we were able to create a slurry that could be flowed even at around 80% concentration.

The high-pressure foaming device 9 is composed of a high-pressure container equipped with a high-pressure air blowing pipe 16 and an agitator 17, and the mixture of foaming agent and water is completely foamed in the high-pressure foaming device 9 to become a high-pressure foam fluid. , are continuously sent to the refoaming device 15.

The re-foaming device 15 is a foam slurry supply device 1 such as a screw feeder or a rotary feeder.
8. High pressure bubble fluid blowout pipe 19 and stirrer 20
It receives the foamed slurry sent from the coal mixer 12 while being pressure-sealed by the supply device 18, and mixes it with the high-pressure foamed fluid sent from the high-pressure foaming device 9. . In this way, the refoaming device ¹⁵ produces a high-pressure, high-concentration foam slurry (for example, coal with a volume concentration of 30 to 40% and a weight concentration of 70 to 80%) that is extremely fluid even under a pressure of about 5 Kgf/cm2. is made.
This foam slurry is further increased to a predetermined flow pressure by a pressure pump 21 such as a plunger pump or a screw pump, and is continuously sent to the foam slurry transport pipe 4. The reason why the high-concentration foam slurry produced under atmospheric pressure by the coal mixer 12 is made into a high-pressure and high-concentration foam slurry by the re-foaming device 15 and then pumped by the pressure pump 21 is as follows. In other words, in order to transport the foamed slurry through a pipeline, a pressure loss of at least the same level as the pressure loss of normal low-concentration water slurry, and in some cases even higher pressure is required. When conveying to ship 2, a minimum pressure of several kgf/cm ² is required.
In addition, the foam slurry made by the coal mixer 12 has very high fluidity under atmospheric pressure, but when the pressure is high as described above, the air bubbles in the slurry are compressed and the volume concentration of coal is becomes large, resulting in a significant decrease in fluidity. For this reason, the foam slurry once made under atmospheric pressure is transferred to the foaming device 15.
The slurry is again mixed with high-pressure foam fluid under a high pressure close to the discharge pressure of the pump 21 to form a high-pressure, high-concentration foam slurry that has sufficient fluidity even under high pressure. In addition, when the pressure pump 21 is required to have a large pressure ratio, it is necessary to increase the mixing ratio of the high pressure bubble fluid in the refoaming device 15 and to reduce the volume concentration of coal.

The high-pressure, high-concentration foam slurry sent out by the pressure pump 21 is sent to the ship 2 through the transport pipe 4, but its pressure decreases as it goes toward the ship 2, that is, downstream. Since the volume of the air bubbles expands, the flow velocity of the slurry increases as it goes downstream. Water and ordinary slurry (solid particles transported by water flow) are incompressible, and their volume does not change with pressure. Therefore, if the cross-sectional area of the pipeline does not change, the average flow velocity of the fluid in the pipe is Constant regardless of pressure. However, when compressible gas is transported, its volume changes (density change) depending on the pressure inside the pipe, and the volumetric flow rate of the gas to be transported changes. That is, if the pipe cross-sectional area does not change, the average flow velocity will change. The above foamed slurry is also a compressible fluid, and as the pressure inside the pipe decreases, the volume of the foam increases and the average flow rate of the slurry increases. For this reason, a stirring device (defoaming device) 22 is provided in the transport pipe 4 at a predetermined position (see FIGS. 2 to 5).
Some of the bubbles are removed from the bubble slurry flowing inside the pipe 4, thereby suppressing an increase in the volume of the slurry, that is, an increase in the flow rate. In pipeline transportation of slurry, the pressure loss during the flow is proportional to the 1st or 2nd power of the flow rate, so an unnecessary increase in the flow rate increases the pressure, ie, the power for the flow. Therefore, the increase in flow velocity is suppressed as described above. The stirring device 22 includes a relatively short, small-diameter guide pipe 23 fixed to the inner wall of the transport pipe 4 in parallel thereto, and a relatively short small-diameter guide pipe 23 fixed to the inner wall of the transport pipe 4 in parallel with the guide pipe 23 on the upstream side (the left side in FIGS. 2 to 5) of the guide pipe 23. It consists of a large-diameter screw feeder 24 and a small-diameter screw feeder 25 placed parallel to the downstream side of the guide pipe 23 (on the right side in the figure). The cross-sectional area is smaller than that on the upstream side. Further, an exhaust pipe 26 is provided in a portion of the guide pipe 23 between the two screw feeders 24 and 25 and protrudes outward through the transport pipe 4, and a valve 27 is attached to the exhaust pipe 26. ing.
The two screw feeders 24 and 25 are constantly driven by separate motors 28, for example, directly as shown in FIG. 2 or via bevel gears as shown in FIG. As time passes, the bubbles in the slurry flowing through the transport pipe 4 become easily broken, especially by mechanical force, and the foam slurry led from the transport pipe 4 into the guide pipe 23 is greatly damaged. Air bubbles in the slurry are separated by stirring with a diameter screw feeder 24,
It is discharged out of the transport pipe 4 through the exhaust pipe 26. Therefore, the volume of the bubble slurry guided into the guide pipe 23 is reduced. The slurry from which the air bubbles have been removed and whose volume has been reduced is sent downstream by the small-diameter screw feeder 25, and is again fed into the transport pipe 4, where it is conveyed together with the remaining air bubble slurry. Therefore, the volume of the entire bubble slurry is also reduced, and an increase in volume due to pressure drop and an increase in flow rate due to the increase in flow rate can be suppressed.
The cross-sectional area and length of the guide pipe 23 and the rotational speed and pitch of each screw feeder 24 and 25 should be adjusted to eliminate foam so that the foam slurry flowing inside the transport pipe 4 does not flow toward the exhaust pipe 26. It is determined as follows, taking into account the amount of slurry, its concentration, pressure, flow rate, etc. That is, A near the entrance of the guide pipe 23
(see Figure 4) and point C near the outlet of the guide pipe 23 are at high pressure, and point B near the inlet of the exhaust pipe 26 in the guide pipe 23 is at low pressure (atmospheric pressure). It is necessary to provide the feeder 24 with a resistance action and the downstream screw feeder 25 with a pump action. At the same time, the opening degree of the valve 27 of the exhaust pipe 26 is adjusted appropriately so that only air is extracted from the transport pipe 4. Also,
Either make the cross-sectional area of the guide pipe 23 between AB larger than that between BC as described above so that the flow rate of slurry between AB is larger than that between BC, or
BC the rotation speed of the screw feeder 24 between AB.
Either it is necessary to make the pitch of the screw feeder 24 between AB larger than that between BC. Furthermore, between AB and
It is desirable to continuously change the pitch of the screw feeders 24, 25 between AB and BC so that there is a flow rate change corresponding to a continuous pressure change between BC. The two screw feeders 24 and 25 may be driven by one motor, and in this case, a transmission using gears or the like may be provided between the screw feeders 24 and 25, or By appropriately selecting the pitch of each screw feeder 24, 25, the feeding capacity of each can be changed. Moreover, when the defoaming ability is small, a plurality of stirring devices 22 are installed. In some cases, a booster pump may be provided in the middle of the transport pipe 4.

The reason why the mixture of foaming agent and water is agitated in the foaming tank 8 and the high-pressure foaming device 9 to foam it, and the foamed slurry is defoamed by stirring in the stirring device 22 is as follows. That's right. That is, the foaming effect of a foaming additive (foaming agent) such as a soap solution does not continue indefinitely, but the foaming effect gradually decreases. Therefore, if a strong mechanical force such as stirring is applied at the stage when the foam reaches the stirring device 22 and the foaming effect has diminished, the foam film will break and the foam will disappear. On the other hand, stirring during foaming in the foaming tank 8 and high-pressure foaming device 9 involves adding gas to the foaming liquid to continuously produce foam. At this time, since the fresh additive has a foaming effect, the mechanical force breaks the cell membrane and fragments the cells, but it is thought that there is almost no defoaming effect. In other words, it is thought that the mechanical energy at this stage is spent not on destroying the bubbles but on fragmenting the bubbles.

The foam slurry sent to the ship 2 through the transport pipe 4 is sent to the antifoam mixer 29 on the ship 2. The antifoaming agent is supplied to the antifoaming agent mixer 29 from the antifoaming agent supply pipe 30, and the foam slurry mixed with the antifoaming agent in the mixer 29 is sent to the solid-gas separator through the foam slurry discharge pipe 31. Sent to 3. As shown in FIG. 6, the solid-gas separator 3 includes a hopper 32 disposed at the discharge end of the bubble slurry discharge pipe 31, and a wire mesh hopper disposed diagonally above the hopper 32. It consists of a screen 33 and a chopper-type stirrer 34 placed at the bottom of the hopper 32. A slurry scattering prevention cover 35 is provided above the hopper 32. The screen 33 may be a shutter-like structure (bar screen) as shown in FIG. The bubble slurry discharged from the discharge pipe 31 is sprayed onto the screen 33, and the bubbles are separated by the impact force, and the slurry after the bubble separation falls from the screen 33 to the lower part of the hopper 32 and is stirred by the stirrer 34. be done. As a result, most of the air bubbles remaining in the slurry disappear, and the slurry from which air bubbles have been removed in this way is continuously introduced into the hold from the outlet 36 at the bottom of the hopper 32. Therefore, compared to the case where the aerated slurry sent through the transport pipe 4 is directly loaded onto the ship 2, the volume concentration of coal in the slurry becomes significantly higher, and the loading efficiency of coal in the hold is improved. In this case, since the screen 33 has a plurality of openings that allow fluid to freely pass through, such as a wire mesh or a bar screen, there is no possibility that the liquid contained in the bubbles will become clogged and cause clogging. , the air of the separated bubbles and a part of the air flow entrained with the bubble slurry can be extracted to the opposite side of the screen 33 to enhance the defoaming effect.

Note that the reason why the slurry is defoamed by stirring in the solid-gas separator 3 is the same as in the case of the stirring device 22 described above.

Effects of the Invention According to the defoaming method for foamed slurry of this invention,
As mentioned above, air bubbles can be efficiently removed from the slurry transported by the pipeline, and the screen will not become clogged, resulting in a high defoaming effect. Therefore, the volume concentration of the particulate matter in the slurry is increased, and the loading efficiency when loading the particulate matter into the hold is significantly improved.

[Brief explanation of drawings]

Fig. 1 is a schematic pipe system diagram showing equipment for carrying out the method of the present invention, Fig. 2 is a schematic sectional view of a stirring device, Fig. 3 is a schematic sectional view showing a modified example of the stirring device, and Fig. 4 is a partially enlarged view of Fig. 2, Fig. 5 is a vertical sectional view of the guide pipe of the stirring device, Fig. 6 is a schematic sectional view of the solid-gas separator, and Fig. 7 is a modified example of the screen of the solid-gas separator. FIG. 3... Solid-gas separator, 4... Foam slurry transport pipe, 5... Mixing tank, 6... Foaming agent tank, 7... Water tank, 8... Foaming tank, 9...
High-pressure foaming device (high-pressure container), 12... Coal mixer,
15... Re-foaming device (high pressure container), 32... hopper, 33... screen, 34... stirrer.

Claims (1)

[Claims] 1. When transporting a foam slurry made by foaming a foamed mixture of a foaming agent and water and a powdery material by a pipeline and shipping it, the foam slurry is transported through a plurality of pipes that allow the fluid to freely pass through the foam slurry. A method for defoaming a foam slurry, which comprises spraying onto a screen having openings to remove the foam and allowing the foam to fall, and stirring the foam slurry that has fallen from the screen to further remove the foam.