Device and method for continuously producing α-type hemihydrate gypsum slurry

Abstract

The present invention discloses a device and a method for continuously producing α-type hemihydrate gypsum slurry. The device for continuously producing α-type hemihydrate gypsum slurry includes a plunger pump, a preheating kettle and a horizontal stirring reaction kettle which are connected in sequence; the plunger pump is used for inputting a dihydrate gypsum slurry formed by mixing powdered dihydrate gypsum, water and a catalyst into the preheating kettle; the preheating kettle is used for preheating the dihydrate gypsum slurry; the horizontal stirring reaction kettle is used for forming α-type hemihydrate gypsum slurry from the preheated dihydrate gypsum slurry under the conditions of heating and stirring, and a decompression pipe is connected to the slurry discharge port of the horizontal stirring reaction kettle. The present invention can continuously produce, without the process step of "drying, adding water, and drying again", and the production energy consumption and carbon dioxide emissions are far lower than those of the traditional process, having the significance of energy conservation and emission reduction and higher production efficiency.

Description

Technical Field

[0001] The present invention relates to a production method and device for gypsum products, and particularly to a production device and method capable of continuously producing α-type hemihydrate gypsum slurry for directly and continuously casting into gypsum products. Background Art

[0002] Currently, the traditional production process of gypsum products is to first heat the crystal water in dihydrate gypsum to convert it into free water and dry it into hemihydrate gypsum (powder), then add water to the hemihydrate gypsum and stir to solidify and form a shape, and finally dry it again; this production process of heating and drying, adding water, and drying again has a large heat consumption (accounting for more than 90% of the total production energy consumption). Especially when using chemical gypsum as raw material, because it already contains a relatively high proportion of free water, before heating and converting the crystal water in it, the free water needs to be dried first, which further increases the production heat consumption of gypsum products.

[0003] If the traditional hydrothermal method process is used to produce α-type hemihydrate gypsum slurry for directly casting gypsum products, since the hydrothermal method uses a vertical reactor, a large amount of process water is required, that is, the weight ratio of the solid raw material (dihydrate gypsum powder) contained in the water medium during production cannot be higher than 30%; this is because without a large amount of water, the concentration of α-type hemihydrate gypsum in the produced α-type hemihydrate gypsum slurry is high. When the temperature decreases and the vapor pressure decreases to atmospheric pressure, the saturated α-type hemihydrate gypsum will be reduced and solidified into massive dihydrate gypsum. Therefore, when using the traditional hydrothermal method process to produce α-type hemihydrate gypsum slurry, heating a large amount of water as the medium requires wasting a large amount of heat energy, and the effective volume ratio of the production equipment is very low, thus increasing the equipment investment and production cost. At the same time, the weight ratio of α-type hemihydrate gypsum in this α-type hemihydrate gypsum slurry is only about 24%, and it cannot be directly cast into gypsum products. It is necessary to dehydrate the α-type hemihydrate gypsum slurry produced by the hydrothermal method using a centrifuge, which further increases the investment in production equipment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a device and method for continuously producing α-type hemihydrate gypsum slurry to achieve the purpose of reducing production energy consumption.

[0005] To solve the above technical problems, according to one aspect of the present invention, a device for continuously producing α-type hemihydrate gypsum slurry is provided, which includes a plunger pump, a preheating kettle, and a horizontal stirring reactor connected in sequence;

[0006] The plunger pump is used to input a dihydrate gypsum slurry formed by mixing powdered dihydrate gypsum, water, and a catalyst into the preheating kettle; the preheating kettle is used to preheat the dihydrate gypsum slurry; the horizontal stirring reactor is used to form α-type hemihydrate gypsum slurry under heating and stirring conditions for the preheated dihydrate gypsum slurry, and a decompression pipe is connected to the slurry discharge port of the horizontal stirring reactor.

[0007] Further, a heating coil is provided outside the preheating kettle body.

[0008] Further, a spiral diversion heating coil is installed inside the preheating kettle.

[0009] Further, the diversion heating coil is in the shape of a frustum spiral structure, and the pitch is 1.3 - 1.5 times the diameter of the diversion heating coil.

[0010] Further, the diameter of the diversion heating coil is one twenty-fifth to one twentieth of the diameter of the preheating kettle.

[0011] According to another aspect of the present invention, there is provided a method for continuously producing α - hemihydrate gypsum slurry, which is implemented by using the above - mentioned device, and includes the following steps:

[0012] Step 1: Mix powdered dihydrate gypsum with water and a trace amount of catalyst to prepare a dihydrate gypsum slurry with a water content of 35% - 40%; continuously pump the dihydrate gypsum slurry into the preheating kettle with a plunger pump;

[0013] Step 2: Heat the dihydrate gypsum slurry in the preheating kettle to 105°C, and then inject it into the horizontal stirring reaction kettle;

[0014] Step 3: Heat the dihydrate gypsum slurry in the horizontal stirring reaction kettle to 130°C and keep it at a constant temperature for reaction, so that the dihydrate gypsum gradually loses one and a half crystal waters to form α - hemihydrate gypsum, thereby obtaining α - hemihydrate gypsum slurry.

[0015] Compared with the prior art, the equipment and method of the present invention have the following advantages and beneficial effects:

[0016] 1. Since the present invention can continuously produce without the process of "drying, adding water, and drying again", the production energy consumption and carbon dioxide emissions of the present invention are much lower than those of the traditional process, which has the significance of energy conservation and emission reduction and higher production efficiency.

[0017] 2. The gypsum products produced from the α - hemihydrate gypsum slurry of the present invention have high strength, wide applications, and high cost performance.

[0018] 3. Since there is no dust emission during the production process of the present invention, compared with the traditional production process, the use of a large dust removal device can be omitted, saving the investment in dust removal equipment and the floor area of the factory building. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the device for continuously producing α - hemihydrate gypsum slurry of the present invention.

[0020] Figure 2It is a schematic structural diagram of the diversion heating coil described in the present invention.

[0021] In the figure, 1 - plunger pump, 2 - preheating kettle, 3 - horizontal stirring reaction kettle, 4 - diversion heating coil, 5 - heat source inlet, 6 - heat source outlet, 7 - connecting column, 8 - slurry discharge port. Detailed implementation manners

[0022] Based on the principle that heating dihydrate gypsum in an aqueous solution to remove one and a half crystal waters can generate α - hemihydrate gypsum, the present invention adopts a horizontal stirring reaction kettle 3 to continuously produce α - hemihydrate gypsum slurry with a large reduction in process water and directly cast it into gypsum products, including a production device and method.

[0023] As Figure 1 shown, a system device for continuously producing α - hemihydrate gypsum slurry provided by a typical implementation manner of the present invention includes a plunger pump 1, a preheating kettle 2, and a horizontal stirring reaction kettle 3 connected in sequence.

[0024] The plunger pump 1 is used to pump a dihydrate gypsum slurry formed by mixing powdered dihydrate gypsum, water, and a catalyst into the preheating kettle 2. The preheating kettle 2 is used to preheat the dihydrate gypsum slurry; the horizontal stirring reaction kettle 3 is used to form α - hemihydrate gypsum slurry under the conditions of continuous heating and simultaneous stirring of the preheated dihydrate gypsum slurry. The α - hemihydrate gypsum slurry output from the horizontal stirring reaction kettle 3 flows into a mixer through a decompression pipe, and after being stirred and mixed with the ingredients of the gypsum product, it is cast onto a conventional gypsum product forming production line.

[0025] The horizontal stirring reaction kettle is adopted because during the process of the material slurry "dihydrate gypsum" removing one and a half crystal waters to generate α - hemihydrate gypsum, the viscosity of the slurry increases, and strong stirring must be used to make the slurry uniformly heated and react.

[0026] In the above - mentioned implementation manners, the slurry discharge port of the horizontal stirring reaction kettle is connected with a decompression pipe, and a steam discharge port is arranged at the top of the decompression pipe. When the hot slurry containing α - hemihydrate gypsum continuously sprays into the decompression pipe, the inner diameter of the decompression pipe suddenly expands relative to the inner diameter of the slurry inlet, so that the pressure of the α - hemihydrate gypsum slurry suddenly decreases to atmospheric pressure. At the same time, a part of the high - temperature water in the slurry vaporizes due to decompression and is discharged through the steam discharge port at the top of the slurry decompression pipe.

[0027] The above - mentioned preheating kettle 2 is equipped with heating equipment. In a relatively specific implementation manner, a heating coil is arranged outside the preheating kettle body.

[0028] In a preferred implementation manner, a spiral diversion heating coil 4 is installed inside the preheating kettle 2, and the spiral diversion heating coil 4 can generate turbulence so that the material slurry can be uniformly heated during the flow process.

[0029] As Figure 1 shown, the heat source inlet 5 and the heat source outlet 6 of the diversion heating coil 4 are respectively arranged on the side wall of the preheating kettle 2, and the heat source inlet 5 is connected to the heating pipeline outside the preheating kettle. The diversion heating coil 4 is fixed to the inner wall of the preheating kettle through the connecting column 7.

[0030] The above-mentioned diversion heating coil 4 and the heating coil outside the preheating kettle are independent of each other, and both preheat the gypsum dihydrate slurry in the preheating kettle 2.

[0031] Relatively specifically, the diversion heating coil 4 is in the shape of a frustum of a cone with a spiral structure, and the pitch is 1.3 - 1.5 times the diameter of the diversion heating coil 4. The diversion heating coil 4 is arranged in the direction of the slurry flow, that is, the small port of the diversion heating coil 4 faces the flow direction of the gypsum dihydrate slurry, disturbing the linear motion of the slurry while heating the slurry material, and the generated turbulent flow enables the material slurry to be evenly heated.

[0032] In a preferred embodiment, the diameter of the diversion heating coil 4 is one twenty-fifth to one twentieth of the diameter of the preheating kettle, and the plane inclination angle of the frustum-shaped spiral structure of the diversion heating coil 4 is 45°; through testing, installing the above-mentioned diversion heating coil that can generate turbulent flow in a preheating kettle with an equal heating area per unit length can reduce the length of the preheating kettle by about half to obtain the same temperature of the gypsum slurry.

[0033] Another typical embodiment of the present invention provides a method for continuously producing α-type hemihydrate gypsum slurry, including the following steps:

[0034] Step 1, mix powdered gypsum dihydrate with water and a small amount of catalyst to prepare a gypsum dihydrate slurry with a water content of 35% - 40%; continuously pump the gypsum dihydrate slurry into the preheating kettle 2 with a plunger pump 1. The catalyst is a chemical additive that helps the α-type hemihydrate gypsum crystals to grow directionally and rapidly, for example: aluminum sulfate + sodium citrate.

[0035] Step 2, heat the gypsum dihydrate slurry in the preheating kettle to 105°C, and then inject it into the horizontal stirring reaction kettle 3.

[0036] Step 3, heat the gypsum dihydrate slurry in the horizontal stirring reaction kettle 3 to 130°C and keep it at a constant temperature for reaction to gradually remove one and a half crystal waters from the gypsum dihydrate to generate α-type hemihydrate gypsum, thereby obtaining α-type hemihydrate gypsum slurry.

[0037] The following further illustrates the technical solution claimed in the present invention through a relatively specific embodiment. However, the embodiment is used to explain the implementation scheme of the present invention and does not exceed the scope of the subject matter of the present invention. The protection scope of the present invention is not limited by the described embodiment. Unless otherwise specifically stated, the materials and reagents used in the present invention can be obtained from commercial products in the art. Example 1

[0038] Powdery gypsum dihydrate is mixed with water and a catalyst (aluminum sulfate + sodium citrate) to prepare a gypsum dihydrate slurry containing 35% - 40% water. The slurry is continuously pumped into the preheating kettle 2 by a plunger pump 1 at a slurry flow rate calculated according to the length of the preheating kettle 2 and the heating rate of the gypsum dihydrate slurry. The gypsum dihydrate slurry generates turbulence after passing through the frustum spiral diversion heating coil 4 in the preheating kettle 2, enabling it to be evenly heated and gradually increasing the temperature of the material slurry. When the slurry is heated to 105°C, it is injected into the horizontal stirring reaction kettle 3. The gypsum slurry is heated to 130°C in the horizontal stirring reaction kettle 3 and kept at a constant temperature for one hour, causing the gypsum dihydrate in the raw material slurry to gradually lose one and a half crystal waters to form α-type hemihydrate gypsum, generating a pressurized hot slurry containing α-type hemihydrate gypsum. When it is continuously sprayed into the slurry pressure reducing pipe, the pressure of the α-type hemihydrate gypsum slurry suddenly decreases to atmospheric pressure. At the same time, a part of the high-temperature water in the slurry vaporizes due to the pressure reduction and is discharged through the exhaust port at the top of the slurry pressure reducing pipe. After that, the α-type hemihydrate gypsum slurry flowing out of the pressure reducing pipe enters the mixer, is mixed with the ingredients of the gypsum product to become a gypsum slurry, and finally is poured onto a conventional gypsum product forming and drying production line until it becomes a high-strength gypsum product.

[0039] According to the theoretical heat consumption for converting gypsum into hemihydrate gypsum powder (per ton) = heat storage of raw materials + heat of gypsum decomposition + heat of vaporization of water = 33920 + 27005 + 96534 = 157459 (kcal) ≈ 157,000 kcal; and in this invention, it is not necessary to dry the hemihydrate gypsum, that is, there is no consumption of heat energy for vaporization. Therefore, this example can reduce energy consumption by about 60% (96534 / 157459).

Claims

1. A method for continuously producing α-type hemihydrate gypsum slurry, characterized in that, it is implemented by using a device for continuously producing α-type hemihydrate gypsum slurry, the device for continuously producing α-type hemihydrate gypsum slurry includes a plunger pump, a preheating kettle and a horizontal stirring reactor connected in sequence; the plunger pump is used to input the dihydrate gypsum slurry formed by mixing powdered dihydrate gypsum, water and a catalyst into the preheating kettle; the preheating kettle is used to preheat the dihydrate gypsum slurry; the horizontal stirring reactor is used to form α-type hemihydrate gypsum slurry from the preheated dihydrate gypsum slurry under heating and stirring conditions, and a decompression pipe is connected to the slurry discharge port of the horizontal stirring reactor; a spiral guide heating coil is installed inside the preheating kettle, the guide heating coil is a frustum-shaped spiral structure, and the pitch is 1.3-1.5 times the diameter of the guide heating coil; the diameter of the guide heating coil is 1 / 25 to 1 / 20 of the diameter of the preheating kettle; the guide heating coil is arranged in the direction of the slurry flow, that is, the small port of the guide heating coil faces the flow direction of the dihydrate gypsum slurry; the plane inclination angle of the frustum-shaped spiral structure of the guide heating coil is 45°; a heating coil is arranged outside the preheating kettle; the implementation process includes the following steps: Step 1, mix powdered dihydrate gypsum with water and a trace amount of catalyst to prepare a dihydrate gypsum slurry with a water content of 35% - 40%; continuously pump the dihydrate gypsum slurry into the preheating kettle with a plunger pump; Step 2, heat the dihydrate gypsum slurry to 105°C in the preheating kettle, and then inject it into the horizontal stirring reactor; Step 3, heat the dihydrate gypsum slurry to 130°C in the horizontal stirring reactor and keep it at a constant temperature for reaction to gradually remove one and a half crystal waters from the dihydrate gypsum to generate α-type hemihydrate gypsum, so as to obtain α-type hemihydrate gypsum slurry.

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