Steam curing and drying device for producing high-strength gypsum from phosphogypsum and its production process

Abstract

Steam curing and drying device for producing high-strength gypsum from phosphogypsum and its production process, including a kettle body (1), at least one steam inlet (3) and a vacuum exhaust port (4) are arranged on the kettle body (1), and at least one heating and circulation device is arranged inside the kettle body (1). The heating and circulation device is used to circulate hot air inside the kettle body (1) to dry the hemihydrate gypsum material generated by steam curing. The advantages are as follows: 1. The steam curing reaction of the phosphogypsum blocks is uniform, and the steam curing speed is fast. Immediately after the steam curing is completed, the drying operation is carried out. The hot air circulation system makes full use of the heat source, saves energy, ensures that the material is evenly heated during steam curing and drying, and has a fast drying speed. 2. The drying and heating process can be carried out simultaneously when discharging steam at the end of autoclaving, greatly reducing the generation of condensate water, and the vacuum exhaust port can efficiently and quickly discharge the water vapor generated during drying, ensuring the product quality.

Description

Technical Field

[0001] The present invention relates to the field of gypsum production equipment, and particularly to a steam curing and drying device for producing high-strength gypsum from phosphogypsum and its production process. Background Art

[0002] At present, using phosphogypsum as raw material to prepare high-value-added high-strength gypsum can effectively solve the problem of phosphogypsum accumulation. The added value of the obtained product is greater than the treatment cost, generating new economic benefits, and having a profound impact on promoting the coordinated development of enterprises, society and the environment. Currently, the common process for producing high-strength gypsum from phosphogypsum is the autoclaving method, and the process is as follows: using purified phosphogypsum slurry - pressure filtration - batching (modifying agent, crystal conversion agent) - mixing - briquetting - stacking - steam curing reaction - drying - crushing - ball milling. After the steam curing reaction, it is necessary to ensure that the free water in the gypsum blocks is dried as soon as possible. The distribution of steam delivery pipes in the existing steam curing reaction device is unreasonable, and the steam curing reaction is uneven, affecting the product quality. After steam curing, the phosphogypsum blocks need to be transported to the drying station for drying. The phosphogypsum blocks will cool slowly during transportation, affecting the product quality. There is a lack of a steam curing and drying device that can integrate the steam curing reaction and drying.

[0003] Patent Publication No.: CN105666670B discloses an autoclave for drying bricks. After heating the circulating water tank at the bottom of the autoclave for a period of time, the water in the tank will be evaporated, and the generated water vapor will enter the steam curing chamber through the connecting pipe, causing a hydrothermal reaction in the bricks; after the water is completely evaporated, the electric heating wire continues to work to heat the gas to achieve drying. The drying process of this invention can only be carried out after the circulating water vapor is completely evaporated, and a large amount of condensed water will be generated during the exhaust process. There is also no steam discharge port during the drying process, which is not conducive to the stability of the high-strength gypsum product quality.

[0004] Patent Publication No.: CN204369762U discloses an autoclave for preparing high-strength α-hemihydrate gypsum from phosphogypsum. The drying and steam pipes share a set of pipes. After steam curing the mixed materials, the pressure is first reduced, and then the hot air generated by the hot blast stove is introduced to achieve the drying of the materials. There is a certain time difference during the conversion process, and the water vapor generated during drying cannot be efficiently discharged. Summary of the Invention

[0005] The purpose of the present invention is to provide a steam curing and drying device for producing high-strength gypsum from phosphogypsum and its production process in view of the above deficiencies.

[0006] The present invention includes a kettle body, at least one steam input port and a vacuum exhaust port are provided on the kettle body, and at least one heating circulation device is provided inside the kettle body. The heating circulation device is used to circulate hot air inside the kettle body to dry the hemihydrate gypsum material generated by steam curing.

[0007] The heating cycle device includes a hot air circulation chamber and a circulation fan. The hot air circulation chamber is installed on the inner wall of the kettle body. A group of hot air outlets are provided on the side wall of the hot air circulation chamber. The circulation fan is installed on the top of the kettle body. The air outlet of the circulation fan is communicated with the hot air circulation chamber, and the air inlet of the circulation fan is located at the top inside the kettle body.

[0008] A partition is provided on the inner wall of the kettle body. A hot air circulation chamber is formed between the partition and the inner wall of the kettle body. Multiple groups of heat exchange pipes are arranged in the hot air circulation chamber. A heat medium inlet and a heat medium outlet are provided on the top of the kettle body. The inlet end of the heat exchange pipe is communicated with the heat medium inlet through a main pipe, and the outlet end of the heat exchange pipe is communicated with the heat medium outlet through a main pipe. Heat medium is input into the heat exchange pipe through the heat medium inlet to heat the circulating air in the hot air circulation chamber.

[0009] At least one steam pipe is provided at the bottom inside the kettle body. A plurality of steam distribution holes are provided on the steam pipe. The steam pipe is communicated with a steam input port. Steam for steam curing is input into the kettle body through the steam nozzles of the steam pipe.

[0010] Tracks are laid at the bottom inside the kettle body. The rail trolley can input or output the phosphogypsum blocks along the tracks.

[0011] The kettle body is a horizontal kettle body. A group of support seats are arranged in sequence at the bottom of the kettle body. A pressure gauge, a safety valve, a pressure alarm and a thermometer are provided on the kettle body.

[0012] S1 Steam curing: The air inside the kettle body is pumped out through the evacuation exhaust port. Saturated water steam is introduced into the kettle body through the steam pipe to raise the temperature of the materials inside the kettle to 120 - 160 °C, the pressure inside the kettle body is 200 - 600 KPa, and steam curing is carried out for 2 - 6 h;

[0013] S2 Drying: After the materials are steam-cured and crystal-transformed, the steam inside the kettle body is discharged through the evacuation exhaust port. The circulation fan is started to circulate the air inside the kettle body. Heat medium is introduced into the heat exchange pipe and output from the hot air outlet to the inside of the kettle body to heat the materials, evaporating the moisture in the materials. The water steam is pumped out through the evacuation exhaust port, and a negative pressure is formed inside the kettle body, reducing the energy consumption for moisture evaporation of the dried materials. The pressure inside the kettle body is 50 - 100 KPa, the drying temperature is 85 - 130 °C, and the drying time is 2 - 6 h.

[0014] The advantages of the present invention are:

[0015] 1. The steam curing reaction of the phosphogypsum blocks is uniform, the steam curing speed is fast. Immediately after the steam curing is completed, the drying operation is carried out. The hot air circulation system makes full use of the heat source, saves energy, ensures that the materials are evenly heated during steam curing and drying, and the drying speed is fast.

[0016] 2. The drying and heating process can be carried out simultaneously when exhausting steam after autoclaving, greatly reducing the generation of condensate water. Moreover, the vacuum exhaust port can efficiently and quickly discharge the water vapor generated during drying, ensuring the product quality. Description of the Drawings

[0017] Figure 1 It is a front view structural schematic diagram of the present invention.

[0018] Figure 2 It is a side view structural schematic diagram of the present invention. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0021] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, in the description of the present invention, if terms such as "first", "second", etc. are only used for distinguishing descriptions, they cannot be understood as indicating or implying relative importance.

[0023] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if the terms "set" and "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] As shown in the attached drawings, the present invention includes a kettle body 1, on which there are provided at least one steam input port 3 and a evacuation and exhaust port 4. Inside the kettle body 1, there is provided at least one heating and circulating device, which is used to circulate hot air inside the kettle body 1 to dry and steam-cure the generated hemihydrate gypsum material.

[0025] The heating and circulating device includes a hot air circulation chamber 5 and a circulation fan 6. The hot air circulation chamber 5 is installed on the inner wall of the kettle body 1. On the side wall of the hot air circulation chamber 5, there is provided a group of hot air outlet ports 7. The circulation fan 6 is installed on the top of the kettle body 1. The outlet of the circulation fan 6 is communicated with the hot air circulation chamber 5, and the inlet of the circulation fan 6 is located at the top inside the kettle body 1.

[0026] On the inner wall of the kettle body 1, there is provided a partition 15. Between the partition 15 and the inner wall of the kettle body 1, a hot air circulation chamber 5 is formed. Inside the hot air circulation chamber 5, there are provided multiple groups of heat exchange pipes 8. On the top of the kettle body 1, there are provided a heat medium inlet 12 and a heat medium outlet 13. The inlet end of the heat exchange pipe 8 is communicated with the heat medium inlet 12 through a main pipe, and the outlet end of the heat exchange pipe 8 is communicated with the heat medium outlet 13 through a main pipe. Heat medium is input into the heat exchange pipe 8 through the heat medium inlet 12 to heat the circulating air inside the hot air circulation chamber 5.

[0027] At least one steam pipe 14 is provided at the bottom inside the kettle body 1. On the steam pipe 14, there are provided multiple steam distribution holes. The steam pipe 14 is communicated with the steam input port 3. Steam for steam curing is input into the kettle body 1 through the steam nozzles of the steam pipe 14.

[0028] Tracks 10 are laid at the bottom inside the kettle body 1. The track trolley can input or output phosphogypsum blocks along the tracks 10.

[0029] The kettle body 1 is a horizontal kettle body. At the bottom of the kettle body 1, there is arranged a group of support seats in sequence. On the kettle body 1, there are provided a pressure gauge, a safety valve, a pressure alarm and a thermometer. Embodiment

[0030] Steam curing process: Stack the phosphogypsum blocks on the rail trolley. After stacking is completed, open the kettle lid 2. The rail trolley transports the phosphogypsum blocks into the kettle body 1, and then close the kettle lid 2 for sealing. Input high-temperature saturated steam through the steam inlet 3 to start steam curing. The condensed water is discharged through the condensed water outlet. After the steam curing is completed, open the evacuation exhaust port 4 to start exhausting and depressurizing, and evacuate the inside of the kettle body 1 to a negative pressure.

[0031] Negative pressure drying process: Pass a high-temperature medium into the heat exchange pipe 8. The high-temperature medium is steam, heat-conducting oil (including but not limited to the above media). Heat the hot air circulation chamber 5. Turn on the circulation fan 6. The input air is heated by the heat exchange pipe 8 and then output from the hot air outlet 7 into the kettle body 1. Inhale the gas through the air inlet of the circulation fan 6 to start circulation. The evaporated water vapor is discharged through the evacuation exhaust port 4. After drying is completed, open the opposite kettle lid 2, and transport the phosphogypsum blocks to the next working station through the rail trolley.

[0032] The existing steam curing process is as follows:

[0033] Pass in saturated steam at 200 - 800 KPa, raise the temperature to 120 - 160 °C, and cook under constant pressure for 6 - 8 h. After steam curing, dry the product at normal pressure at 90 - 160 °C for 3 - 9 h.

[0034] The improved process is as follows:

[0035] S1 Steam curing: Extract the air inside the kettle body 1 through the evacuation exhaust port 4. Pass saturated steam into the kettle body 1 through the steam pipe 14 to raise the temperature of the materials inside the kettle to 120 - 160 °C. The pressure inside the kettle body 1 is 200 - 600 KPa, and steam cure for 2 - 6 h;

[0036] S2 Drying: After the materials are steam cured and crystal transformed, discharge the steam inside the kettle body 1 through the evacuation exhaust port 4. Start the circulation fan 6 to circulate the air inside the kettle body 1. Pass a heat medium into the heat exchange pipe 8, and output it from the hot air outlet 7 into the kettle body 1 to heat the materials, evaporate the water in the materials, and extract the water vapor through the evacuation exhaust port 4. A negative pressure is formed inside the kettle body 1 to reduce the energy consumption of water evaporation for drying the materials. The pressure inside the kettle body 1 is 50 - 100 KPa, the drying temperature is 85 - 130 °C, and the drying time is 2 - 6 h.

[0037] According to JC / T2038 - 2010, measure the strength data of the products obtained from the existing technology and the improved technology, and record the data results in Table 1 and Table 2.

[0038] Table 1

[0039]

[0040] The high-strength gypsum prepared according to the present invention shortens the steam curing time in the steam curing process.

[0041] Table 2

[0042]

[0043] The high-strength gypsum prepared according to the present invention shortens the drying time in the drying process, and its flexural strength and compressive strength are superior to those of the existing high-strength gypsum.

Claims

1. An autoclaving and drying device for producing high-strength gypsum from phosphogypsum, comprising a kettle body (1), characterized in that, At least one steam inlet (3) and a evacuation and exhaust port (4) are provided on the kettle body (1). At least one heating and circulation device is provided inside the kettle body (1). The heating and circulation device is used to circulate hot air inside the kettle body (1) to dry the hemihydrate gypsum material generated by steam curing. The heating and circulation device includes a hot air circulation chamber (5) and a circulation fan (6). The hot air circulation chamber (5) is installed on the inner wall of the kettle body (1). A group of hot air outlets (7) are provided on the side wall of the hot air circulation chamber (5). The circulation fan (6) is installed on the top of the kettle body (1). The outlet of the circulation fan (6) is communicated with the hot air circulation chamber (5). The inlet of the circulation fan (6) is located at the inner top of the kettle body (1). A partition plate (15) is provided on the inner wall of the kettle body (1). A hot air circulation chamber (5) is formed between the partition plate (15) and the inner wall of the kettle body (1). Multiple groups of heat exchange pipes (8) are provided inside the hot air circulation chamber (5). A heat medium inlet (12) and a heat medium outlet (13) are provided on the top of the kettle body (1). The inlet end of the heat exchange pipe (8) is communicated with the heat medium inlet (12) through a main pipe. The outlet end of the heat exchange pipe (8) is communicated with the heat medium outlet (13) through a main pipe. Heat medium is input into the heat exchange pipe (8) through the heat medium inlet (12) to heat the circulating air in the hot air circulation chamber (5). At least one steam pipe (14) is provided at the inner bottom of the kettle body (1). Multiple steam distribution holes are provided on the steam pipe (14). The steam pipe (14) is communicated with the steam inlet (3). Steam for steam curing is input into the kettle body (1) through the steam nozzles of the steam pipe (14).

2. The steam curing and drying device for producing high-strength gypsum from phosphogypsum according to claim 1, characterized in that, Tracks (10) are laid at the inner bottom of the kettle body (1). The rail trolley can input or output phosphogypsum blocks along the tracks (10).

3. The steam curing and drying device for preparing high-strength gypsum from phosphogypsum according to claim 1, characterized in that, The kettle body (1) is a horizontal kettle body. A group of support seats are arranged in sequence at the bottom of the kettle body (1). A pressure gauge, a safety valve, a pressure alarm and a thermometer are provided on the kettle body (1).

4. A steam curing and drying process of a steam curing and drying device for producing high-strength gypsum from phosphogypsum according to any one of claims 1-3, characterized in that S1 Steam curing: The air inside the kettle body (1) is extracted through the evacuation and exhaust port (4). Saturated steam is introduced into the kettle body (1) through the steam pipe (14) to raise the temperature of the materials inside the kettle to 120-160°C, and the pressure inside the kettle body (1) is 200-600 KPa. Steam curing is carried out for 2-6 h; S2 Drying: After the materials are steam-cured and crystal-transformed, the steam inside the kettle body (1) is discharged through the evacuation and exhaust port (4). The circulation fan (6) is started to circulate the air inside the kettle body (1). Heat medium is introduced into the heat exchange pipe (8) and output from the hot air outlet (7) into the kettle body (1) to heat the materials, evaporating the moisture in the materials. The water vapor is extracted through the evacuation and exhaust port (4). A negative pressure is formed inside the kettle body (1) to reduce the energy consumption of moisture evaporation of the dried materials. The pressure inside the kettle body (1) is 50-100 KPa, the drying temperature is 85-130°C, and the drying time is 2-6 h.

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