JP2016121031A - Production method and production device of gypsum slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress entrainment of air into a slurry discharged from a slurry mixing tank, and stabilize a performance of a liquid pump.CONSTITUTION: A dihydrate gypsum aqueous slurry is supplied from a supply port, along an inner peripheral direction of a cylindrical mixing tank, thereby a slurry revolving stream is formed in the mixing tank, and gypsum hemihydrate powder is put from an upper part of the mixing tank. Then, the slurry is discharged from a discharge port on a position of the mixing tank, except for a side face, or a central part of a bottom face of the mixing tank, toward a same direction of the revolving stream.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and an apparatus for producing a gypsum slurry.

The inventors have developed a technology for recycling gypsum from gypsum board waste. And (Patent Document 1: WO2012 / 176688) 1) Crushing gypsum board waste material, removing foreign substances, and then heating to make a half-water gypsum powder. And mix in a mixing tank
3) Precipitating dihydrate gypsum in the slurry in the crystallization tank, 4) refluxing a part of the slurry to the mixing tank, 5) removing the remainder of the slurry from the crystallization tank to remove fibrous foreign matter, ) It was proposed that the slurry be dehydrated into dihydrate gypsum powder.

  Next, the inventors faced the problem that, when supplying hemihydrate gypsum powder to the slurry mixing tank, the supply port was blocked by the scale in which water vapor from the slurry reacted with hemihydrate gypsum. . Therefore, Patent Document 2 (WO2014 / 141926) discloses that this problem can be solved by heating the tip of the supply port to prevent condensation of water vapor. In the slurry mixing tank of Patent Document 2, hemihydrate gypsum powder is charged from the top of the tank, and the slurry of dihydrate gypsum is supplied from the side of the tank to circulate in the tank, and the slurry is discharged from the discharge port at the bottom of the tank. Discharge. The discharged slurry is supplied to the crystallization tank by a liquid pump.

WO2012 / 176688 WO2014 / 141926

  The inventor faced the problem that in the slurry mixing tank of Patent Document 2, the performance of the discharge liquid pump was not stable, and the flow rate of the gypsum slurry fluctuated. This was due to cavitation, and the slurry was discharged from the discharge port at the center of the bottom of the slurry mixing tank, so it was found that the cause was that vortex was generated in the slurry and air was easily trapped.

  An object of the present invention is to suppress the entrainment of gas into the slurry discharged from the slurry mixing tank and to stabilize the performance of the subsequent liquid pump.

  In this invention, by supplying an aqueous slurry of dihydrate gypsum from the supply port along the inner circumferential direction of the cylindrical mixing tank, a swirling flow of the slurry is formed in the mixing tank, and the upper part of the mixing tank Then, the powder of hemihydrate gypsum is charged and mixed in the slurry, and the slurry mixed with hemihydrate gypsum is discharged from the mixing tank. The present invention is characterized in that the slurry is discharged in the same direction as the direction of the swirling flow from a discharge port provided at a position excluding the central portion of the side surface or the bottom surface of the mixing tank.

The present invention also provides a cylindrical mixing tank, an inlet for supplying hemihydrate gypsum powder from the top of the mixing tank, and a supply for supplying dihydrate gypsum slurry in the direction along the inner circumferential direction of the mixing tank. A gypsum slurry production apparatus comprising a mouth,
A discharge port for discharging the slurry in the same direction as the direction of the swirling flow of the slurry is provided at a position excluding the central portion of the side surface or the bottom surface of the mixing tank.

  In the present invention, a discharge port for discharging the slurry in the same direction as the direction of the swirling flow of the slurry is provided at a position excluding the central portion of the side surface or the bottom surface of the mixing tank. For this reason, the vortex which flows toward the center part of a bottom face does not arise, and since there is little entrainment of a bubble, cavitation of a liquid pump can be controlled.

  Preferably, a protrusion higher than the liquid level of the slurry during normal operation is provided at the center of the bottom surface of the mixing tank, and the slurry is excluded from the space occupied by the protrusion. In the present invention, the slurry is supplied along the inner circumferential direction of the mixing tank, and the slurry is discharged in the same direction as the swirling flow of the slurry from a position excluding the central portion of the bottom portion, that is, from the side portion of the bottom portion. For this reason, in plan view, stagnation occurs in the central portion of the mixing tank, and mixing of the hemihydrate gypsum and the slurry tends to be insufficient in the central portion of the mixing tank. Therefore, if a protrusion is provided in the central portion of the mixing tank and the slurry is removed from the central portion by the protrusion, mixing failure can be suppressed.

  More preferably, when the protrusion is open at the top and the discharge port is clogged, the slurry overflows from the opening at the top of the protrusion into the protrusion. When the scale or the like is generated due to poor mixing or the like and the fluidity of the slurry is lowered, the discharge port may be clogged. Therefore, if an opening is provided in the upper part of the protrusion, the slurry overflows into the protrusion when the discharge port is clogged, so that the liquid level of the mixing tank does not rise abnormally.

  Particularly preferably, a shield is provided in the upper part of the opening, and the shield prevents the powder of hemihydrate gypsum from scattering into the opening. It is inconvenient if the hemihydrate gypsum powder is scattered in the mixing tank and the powder enters the projections from the openings to generate scales. Therefore, a cylindrical or umbrella-shaped shield is provided on the upper portion of the opening to cover the opening, thereby preventing the hemihydrate gypsum powder from entering the opening. In addition, it is preferable that the charging port of the hemihydrate gypsum powder is spaced from the surface of the slurry to prevent the scale from adhering to the charging port. Further, it is preferable that the charging port is provided not in the central part of the mixing tank but in the peripheral part, that is, in the side part in a plan view, so as to avoid the shield and to input the powder onto the swirling flow of the slurry.

  It is preferable to monitor the liquid level in the mixing tank in preparation for clogging of the discharge port. However, when a liquid level sensor is provided in the mixing tank, the adhering hemihydrate gypsum powder becomes a scale, and it is difficult to make the liquid level sensor function normally. Therefore, most preferably, the slurry overflowing into the protrusion from the opening is detected by a sensor, and when the slurry is detected by the sensor, the charging of the hemihydrate gypsum powder and the supply of the aqueous slurry of dihydrate gypsum are stopped. . If it does in this way, when overflow arises, the injection | pouring of the powder of hemihydrate gypsum and the supply of the aqueous slurry of dihydrate gypsum can be stopped exactly.

Main part horizontal direction sectional drawing of the gypsum slurry manufacturing apparatus of an Example Principal section of the gypsum slurry production apparatus of the embodiment in the vertical direction

  Examples for carrying out the present invention are shown below. The scope of the present invention should be determined according to the understanding of those skilled in the art based on the description of the scope of the claims, taking into account the description of the specification and well-known techniques in this field.

  1 and 2 show a gypsum slurry production apparatus 2 according to an embodiment. 4 is a mixing tank, the shape is cylindrical, the axis is vertically oriented, and hemihydrate gypsum powder is charged from the inlet 6 at the upper side. 8 is a jacket that heats the vicinity of the tip of the pipe of the inlet 6 and prevents the scale of the absorbed half-water gypsum. The jacket 8 need not be provided. The position of the inlet 6 may be the side of the ceiling surface of the mixing tank 4 as indicated by reference numeral 7 in FIG. The upper side surface of the mixing tank 4 and the side part of the ceiling surface (positions excluding the central part) are collectively referred to as the upper peripheral part of the mixing tank 4. The upper side surface is limited to a position higher than the liquid level of the slurry.

  Reference numeral 10 denotes a dihydric gypsum slurry supply port, and a slurry in which the dihydrate gypsum is dispersed in an aqueous medium such as water is refluxed from the crystallization tank or the like to the mixing tank 4. The supply port 10 is a lower side surface of the mixing tank, for example, at a height position near the liquid level higher than the bottom surface. The slurry supply direction faces the inner periphery of the mixing tank 4, and is counterclockwise in plan view in FIG. The slurry is fed to form a swirling flow around. A slurry discharge port 12 is provided on the side surface of the bottom of the mixing tank 4 so that the slurry flows into the discharge port 12 along the swirling direction. The discharge port 12 is at a lower position than the supply port 10, and a swirling flow is generated from the supply port 10 to the discharge port 12 as indicated by the arrow in FIG. It descends toward the bottom 14 of 4 and is discharged. The discharge port 12 may be provided on a side portion of the bottom surface 14 of the mixing tank 4 (a position excluding a central portion of the bottom surface 14). The lower part of the side surface of the mixing tank 4 and the side part of the bottom surface are collectively referred to as the bottom peripheral part of the mixing tank 4.

  Reference numeral 20 denotes a protrusion that protrudes vertically upward from the bottom of the mixing tank 4 and has an opening 22 at the upper end thereof. The opening 22 is covered by a shield 24 that hangs down from the ceiling surface 41 of the mixing tank 4. The opening 22 of the protrusion 20 is at a position higher than the liquid level during normal operation. The lower end of the shield 24 is lower than the upper end of the protrusion 20, and the hemihydrate gypsum powder from the inlet 6 does not easily enter the opening 22. The shield 24 may be any shape as long as it covers the opening 22 and suppresses the intrusion of the hemihydrate gypsum powder.

  The liquid pump 30 on the downstream side of the discharge port 12 sends the slurry to the crystallization tank, and the input means 32 such as a conveyor on the upstream side of the input port 6 controls the input of hemihydrate gypsum, and the valve on the upstream side of the supply port 10 The supply means 34 such as a pump controls the supply of the dihydrate gypsum slurry to the mixing tank 4. A control unit 36 controls the liquid pump 30 to the supply unit 34.

  As shown in FIG. 2, in the mixing tank 4, the shield 24 is suspended from the ceiling surface 41, and an exhaust valve 42 is provided on the ceiling surface 41. An opening 23 connected to the outside of the mixing tank 4 is provided at the bottom of the protrusion 20, and a container 44 is provided below the opening 23 so as to receive the overflowed slurry. Further, for example, a sensor S is provided in the container 44, and the presence or absence of slurry in the container or the liquid level of the slurry is measured. Here, the sensor S is a liquid level sensor and detects when the slurry has accumulated up to the position of the chain line in FIG. A slurry may be detected by arranging a sensor S ′ using light scattering in the vicinity of the protrusion 20. Further, the weight of the container 44 may be monitored by a load cell, a strain sensor or the like, and the presence or absence of slurry may be monitored. When the overflowing slurry is detected, the control unit 36 stops the feeding of the hemihydrate gypsum powder from the feeding means 32 and the feeding of the slurry from the feeding means 34, and the outlet 12 is cleaned to prevent clogging. Eliminate.

  The operation of the embodiment will be described. Hemihydrate gypsum powder is charged from the inlet 6, and the inlet 6 is heated by the jacket 8 to prevent the water vapor from the liquid surface from reacting with the hemihydrate gypsum and generating scale. Place 6 at the top of the mixing tank. Also, a slurry of dihydrate gypsum is supplied from the supply port 10 in the circumferential direction of the mixing tank 4, and discharged from the discharge port 12, forming a swirling flow of slurry in the mixing tank 4, and stirring the slurry and hemihydrate gypsum. And mix.

  The flow of the slurry in the mixing tank 4 is a swirling flow that spirally descends along the wall surface, and the air is hardly involved and cavitation in the liquid pump 30 hardly occurs. Since the swirling flow of the slurry stagnates in the central portion of the mixing tank 4 in plan view, the stagnation of the protrusions 20 is prevented. The opening 22 at the top of the protrusion 20 is used as an escape port for slurry when the liquid level abnormally rises, and a shield 24 is provided to prevent the scale absorbed by the half-water gypsum from adhering to the opening 22. When the discharge port 12 or the like is clogged, the overflowed slurry is received in the container 44, and the sensor S monitors whether there is an overflow. If the sensor S is arranged in the mixing tank 4, detection becomes difficult due to adhesion of scales and the like.

2 Gypsum slurry production equipment
4 Mixing tank
6 slot
8 jacket
10 Supply port
12 outlet
14 Bottom
20 protrusion
22,23 opening
24 Shield
30 Liquid pump
32 Input method
34 Supply means
36 Control unit
40 props
41 Ceiling
42 Exhaust valve
44 containers

S, S 'sensor

Claims (6)

By supplying an aqueous slurry of dihydrate gypsum from the supply port along the inner circumferential direction of the cylindrical mixing tank, a swirling flow of the slurry is formed in the mixing tank, and a half-flow from the upper part of the mixing tank is performed. In the method for producing gypsum slurry, the powder of water gypsum is charged and mixed in the slurry, and the slurry mixed with hemihydrate gypsum is discharged from the mixing tank.
A method for producing a gypsum slurry, wherein the slurry is discharged from a discharge port provided at a position excluding a central portion of a side surface or a bottom surface of the mixing tank in the same direction as a swirling flow direction.   The gypsum slurry according to claim 1, wherein a protrusion higher than the liquid level of the slurry during normal operation is provided at the center of the bottom surface of the mixing tank so that the slurry is excluded from the space occupied by the protrusion. Manufacturing method.   3. The method for producing a gypsum slurry according to claim 2, wherein when the projection is opened at the top and the discharge port is clogged, the slurry is allowed to overflow from the opening at the top of the projection into the projection.   4. The method for producing a gypsum slurry according to claim 3, wherein a shield is provided at an upper portion of the opening, and the shielding prevents the powder of hemihydrate gypsum from scattering into the opening. The slurry that overflows into the protrusion from the opening is detected by a sensor,
The method for producing a gypsum slurry according to claim 3 or 4, wherein when the slurry is detected by the sensor, charging of the hemihydrate gypsum powder and supply of the aqueous slurry of dihydrate gypsum are stopped. A cylindrical mixing tank, a charging port for supplying hemihydrate gypsum powder from the upper part of the mixing tank, a supply port for supplying dihydrate gypsum slurry in the direction along the inner circumferential direction of the mixing tank, and An apparatus for producing gypsum slurry, comprising:
An apparatus for producing a gypsum slurry, wherein a discharge port for discharging the slurry in the same direction as the direction of the swirling flow of the slurry is provided at a position excluding the central portion of the side surface or bottom surface of the mixing tank.

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