Calcium aluminate powder and polyaluminum combined production process and device

Abstract

The present invention relates to the technical field of chemical production, and discloses a combined production process and device for calcium aluminate powder and polyaluminum. In the combined production process of calcium aluminate powder and polyaluminum, the polyaluminum solution is sprayed onto the outer wall of a rotary kiln, and the polyaluminum solution is dried by using the radiant heat of the rotary kiln body to obtain solid polyaluminum. The rotary kiln is used for the calcination process in the production process of calcium aluminate powder. The combined production device for calcium aluminate powder and polyaluminum includes a rotary kiln, a waste heat steam boiler, a reaction kettle, a plate and frame filter press, and a liquid storage tank. The present invention realizes the full recovery of heat in the production process of calcium aluminate powder and uses it in the production process of polyaluminum, effectively reducing energy consumption and improving economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and particularly relates to a combined production process and device for calcium aluminate powder and polyaluminum chloride. Background Art

[0002] In the existing production process of calcium aluminate powder, a rotary kiln calcination process is mainly used. During this production process, a large amount of heat is generated in the kiln body, and a large amount of heat is also carried away by the flue gas at the kiln tail discharged from the kiln body. These energies cannot be effectively utilized in the calcium aluminate powder production process, resulting in energy waste; while in the production process of polyaluminum chloride, calcium aluminate powder is required as a raw material to react with hydrochloric acid, and a large amount of steam is required to provide heat during the reaction process. The polyaluminum chloride solution after pressure filtration requires a large amount of natural gas to provide heat for the drying of polyaluminum chloride, with high energy consumption and high product cost.

[0003] Therefore, how to combine the production processes of calcium aluminate powder and polyaluminum chloride and apply the waste heat in the calcium aluminate powder production process to the polyaluminum chloride production is a problem that needs to be solved by the practitioners in this industry. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention provides a combined production process and device for calcium aluminate powder and polyaluminum chloride.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A combined production process for calcium aluminate powder and polyaluminum chloride, spraying the polyaluminum chloride solution onto the outer wall of the rotary kiln, and using the radiant heat of the rotary kiln body to dry the polyaluminum chloride solution to obtain solid polyaluminum chloride. The rotary kiln is used for the calcination process in the production of calcium aluminate powder.

[0007] Preferably, the polyaluminum chloride solution is sprayed onto the firing section of the rotary kiln. The temperature of the outer wall of the firing section of the rotary kiln is 240 - 300 degrees Celsius, the rotation speed of the rotary kiln is 0.5 - 4.3 r / min, and the flow rate of the polyaluminum chloride solution is 5 - 11 cubic meters / h.

[0008] Preferably, the rotation speed of the rotary kiln is 3.2 - 4.3 r / min.

[0009] Preferably, collecting the flue gas at the kiln tail discharged from the rotary kiln into a waste heat steam boiler. The waste heat steam boiler uses the waste heat in the flue gas at the kiln tail to generate steam, and introducing the steam into the reaction kettle for reaction heat supply. The reaction kettle is used for the reaction of calcium aluminate powder and hydrochloric acid to generate a polyaluminum chloride feed liquid, and separating the solid and liquid of the polyaluminum chloride feed liquid to obtain a polyaluminum chloride solution.

[0010] Preferably, the steam generated by the waste heat steam boiler has a temperature of 160 degrees Celsius and a steam flow rate of 9 T / h. The flue gas at the kiln tail enters the flue gas treatment device at the kiln tail after being cooled by the waste heat steam boiler.

[0011] The calcium aluminate powder and polyaluminum combined production device includes a rotary kiln, a waste heat steam boiler, a reaction kettle, a plate and frame filter press, and a liquid storage tank. The tail gas outlet of the rotary kiln is connected to the waste heat steam boiler, the steam outlet of the waste heat steam boiler is connected to the reaction kettle, the discharge port of the reaction kettle is connected to the plate and frame filter press, the discharge port of the plate and frame filter press is connected to the liquid storage tank, and the discharge port of the liquid storage tank is connected to an atomizing device through a shunt device. The atomizing device includes a conveying pipeline arranged on one side of the rotary kiln and a sector nozzle connected to the conveying pipeline.

[0012] Preferably, it further includes a cleaning and collecting device. The cleaning and collecting device includes a cleaning scraper, a material receiving chute, and a conveying device. The cleaning scraper abuts against the outer side wall of the rotary kiln, the material receiving chute is arranged on the side of the scraper, and the conveying device is located below the material receiving chute.

[0013] Preferably, the bottom of the cleaning scraper is rotatably connected to a bracket, and the middle of the cleaning scraper is connected to the bracket through a spring.

[0014] The present invention uses the heat in the kiln tail flue gas to produce steam and uses the rotary kiln body to dry the polyaluminum solution, thereby realizing the full recovery of heat in the calcium aluminate powder production process and using it in the polyaluminum production process, effectively reducing energy consumption and improving economic benefits. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of Example 4.

[0016] Figure 2 It is a schematic structural diagram of the cleaning and collecting device in Example 4.

[0017] Figure 3 It is the front view of the waste heat steam boiler in Example 4.

[0018] Figure 4 It is the top view of the waste heat steam boiler in Example 4.

[0019] Figure 5 It is the internal structural schematic diagram of the waste heat steam boiler in Example 4.

[0020] In the figure: 1. Rotary kiln; 2. Waste heat steam boiler; 3. Reaction kettle; 4. Plate and frame filter press; 5. Liquid storage tank; 6. Conveying pipeline; 7. Sector nozzle; 8. Cleaning scraper; 9. Material receiving chute; 10. Conveying device; 11. Spring. Detailed Embodiments

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Example 1

[0023] The co-production process of calcium aluminate powder and polyaluminum. The polyaluminum solution is sprayed onto the outer wall of the rotary kiln, and the radiant heat of the rotary kiln body is used to dry the polyaluminum solution to obtain solid polyaluminum. The rotary kiln is used for the calcination process in the production of calcium aluminate powder.

[0024] The polyaluminum solution is sprayed onto the firing section of the rotary kiln. The temperature of the outer wall of the firing section of the rotary kiln is 240 - 300 degrees Celsius, the rotation speed of the rotary kiln is 3.2 - 4.3 r / min, and the flow rate of the polyaluminum solution is 5 cubic meters / h.

[0025] The kiln tail gas discharged from the rotary kiln is collected into the waste heat steam boiler. The waste heat steam boiler uses the waste heat in the kiln tail gas to generate steam, and the steam is introduced into the reaction kettle for reaction heating. The reaction kettle is used for the reaction of calcium aluminate powder and hydrochloric acid to generate polyaluminum feed liquid, and the polyaluminum feed liquid is subjected to solid-liquid separation to obtain polyaluminum solution.

[0026] The steam generated by the waste heat steam boiler has a temperature of 160 degrees Celsius and a steam volume of 9 T / h. The kiln tail gas enters the kiln tail gas treatment device after being cooled by the waste heat steam boiler.

[0027] In this embodiment, the rotary kiln uses coal or natural gas as fuel, and the whole rotary kiln is heated through a multi-channel burner. The temperature of the firing section reaches about 1200 degrees Celsius, the temperature of the kiln tail gas is as high as 600 degrees Celsius, and the flow rate is about 40000 Nm 3 / h. In the prior art, the kiln tail gas is usually cooled to below 200 degrees Celsius and then directly discharged after being treated up to standard by a high-temperature bag filter and desulfurization and denitrification equipment. A large amount of waste heat in the kiln tail gas is wasted in the cooling stage, resulting in great energy waste. And a large amount of heat is just needed in the polyaluminum reaction. The adoption of this production process can effectively recycle the high-temperature kiln tail gas.

[0028] Adopting the above co-production process of calcium aluminate powder and polyaluminum has the following benefits:

[0029] Select a volume of 50 - 100 m 3The reactor can raise the solution in the reactor to 100 degrees Celsius within 2.5 hours under the most adverse conditions in winter. Then, only a small amount of steam needs to be introduced to supplement the lost heat to ensure the progress of the chemical reaction. The steam generated by the flue gas at the kiln tail can fully meet the continuous production demand of polyaluminum.

[0030] Since the polyaluminum liquor contains hydrochloric acid, an acid mist absorption tower is provided on the reactor in this embodiment to absorb the acidic components in the polyaluminum liquor. And the firing section of the rotary kiln is made of stainless steel. The temperature in the firing section is relatively high, and the hydrochloric acid in the polyaluminum liquor volatilizes with the water vapor. The acid-containing water vapor is pumped to the absorption tower and neutralized with alkali liquor before being discharged.

[0031] Example 2

[0032] The difference between this embodiment and Example 1 is only that: the flow rate of the polyaluminum solution is 11 cubic meters / h.

[0033] Example 3

[0034] The difference between this embodiment and Example 1 is only that: the flow rate of the polyaluminum solution is 9.5 cubic meters / h.

[0035] Example 4

[0036] See Figures 1-5 , the calcium aluminate powder and polyaluminum combined production device, used for the calcium aluminate powder and polyaluminum combined production process of Example 1, includes a rotary kiln 1, a waste heat steam boiler 2, a reactor 3, a plate and frame filter press 4, and a liquid storage tank 5. The tail gas outlet of the rotary kiln is connected to the waste heat steam boiler, the steam outlet of the waste heat steam boiler is connected to the reactor, the discharge port of the reactor is connected to the plate and frame filter press, the discharge port of the plate and frame filter press is connected to the liquid storage tank, the discharge port of the liquid storage tank is connected with an atomizing device through a shunt device. The atomizing device includes a conveying pipeline 6 arranged on one side of the rotary kiln and a fan-shaped nozzle 7 connected to the conveying pipeline. The fan-shaped nozzle sprays towards the outer wall of the firing section of the rotary kiln. The flow rate of the fan-shaped nozzle is 5 - 11 cubic meters / h, and it is adjusted according to the temperature and dryness of the outer wall of the rotary kiln.

[0037] The soft water for the waste heat steam boiler is measured by a water meter, and the steam flow rate is measured by a vortex flowmeter. The calcium aluminate powder is quantitatively added to the reactor through a sealed spiral auger scale. During the reaction process, the opening degree of the steam pipeline valve is automatically controlled by a temperature sensor and a PID control instrument to stabilize the material temperature in the reactor.

[0038] The shunt device is a shunt pipeline and an electric control valve. An electric control valve can be installed when the polyaluminum solution after pressure filtration is transported through the pipeline to adjust the flow rate and pressure in each branch pipe, so that the atomizing device can operate better.

[0039] The atomizing device is a fan-shaped nozzle made of 2205 stainless steel. Through the pressurization of the discharge pump and the flow control of the shunt device, the polyaluminum solution is evenly sprayed onto the surface of the rotary kiln cylinder. When the atomizing effect of the stainless steel nozzle is not good or after an interval of time, high-pressure compressed air will be automatically blown to clean the materials adhered to the nozzle and ensure the atomizing effect of the nozzle.

[0040] This embodiment further includes a cleaning and collecting device. The cleaning and collecting device includes a cleaning scraper 8, a material receiving chute 9, and a conveying device 10. The cleaning scraper abuts against the outer wall of the rotary kiln. The material receiving chute is arranged on the side of the scraper, and the conveying device is located below the material receiving chute.

[0041] The bottom of the cleaning scraper is rotatably connected to the bracket, and the middle of the cleaning scraper is connected to the bracket through a spring 11.

[0042] The polyaluminum liquid material produced by the reaction in the reactor is subjected to solid-liquid separation by a plate and frame filter press to obtain a polyaluminum solution. The polyaluminum solution is stored in a liquid storage tank. The polyaluminum solution in the liquid storage tank is evenly sprayed onto the outer wall of the rotary kiln through a circulation pump, a metering device, a shunt device, and an atomizing device. After the polyaluminum solution on the rotary kiln is dried and cleaned, it is collected by the cleaning and collecting device.

[0043] The conveying device is a high-temperature resistant conveyor belt or a screw conveyor.

[0044] Comparative Example 1

[0045] The difference between this embodiment and Embodiment 1 is only that: the flow rate of the polyaluminum solution is 3.4 cubic meters / h.

[0046] Comparative Example 2

[0047] The difference between this embodiment and Embodiment 1 is only that: the flow rate of the polyaluminum solution is 13.7 cubic meters / h.

[0048] The polyaluminum products are produced respectively by the methods of Embodiments 1-3 and Comparative Examples 1-2. The water content of the obtained polyaluminum is shown in the following table.

[0049] Water content Example 1 2.8％ Example 2 4.3％ Example 3 3.3％ Comparative Example 1 1.4％ Comparative Example 2 6.8％

[0050] Among them, the polyaluminum products obtained by the methods of Embodiments 1-3 and Comparative Example 2 do not have the phenomenon of material caking, while the polyaluminum product obtained by Comparative Example 1 has the phenomenon of material caking, forming hard flaky solids, which need to be broken.

[0051] As can be seen from the above comparison, when the flow rate of the polyaluminum solution is 5-11 cubic meters per hour, polyaluminum products with low water content (meeting the standard that the water content of polyaluminum products ≤ 5%) and no material caking can be obtained, which can maximize the utilization of the radiant heat of the rotary kiln body while ensuring the quality of polyaluminum products and fully recover energy.

[0052] This production process is carried out on the premise of not affecting the normal production of the rotary kiln. During the normal production of calcium aluminate powder in the rotary kiln, the consumption of natural gas and the rotational speed of the rotary kiln may change. It is necessary to cooperate with the rotational speed of the rotary kiln and the surface temperature of the kiln body to adjust the drying amount of the polyaluminum solution on the rotary kiln body without affecting the production of calcium aluminate powder. By detecting the temperature of the outer surface of the kiln and the rotational speed of the rotary kiln body (the normal rotational speed of the rotary kiln is 0.5-4.3 r / min), the atomization efficiency of the nozzle is automatically adjusted through the control software in the central control room, so that the material sprayed by the atomizing nozzle onto the rotary kiln body can be dried normally (the thickness of the slurry on the rotary kiln wall is controlled within the range of 0.5-5 mm and vaporizes and dries on the kiln body). Due to the influence of the radiant heat of the rotary kiln, solid deposits will form on the surface of the sector nozzle after a long time, affecting the atomization effect. Through theoretical calculation and on-site use calculation, solid deposits will occur at the nozzle after 30 to 42 minutes of normal operation, and the atomization effect will be significantly reduced. Therefore, the electric valves of the on-site steam pipeline and compressed air pipeline are controlled by the automatic control system to stop the material conveying of the nozzle every 25 minutes and open the bypass steam and compressed air valves to automatically clean the nozzle with steam for 5 seconds, which can ensure the production stability of each batch of polyaluminum. Since the liquid polyaluminum can quickly evaporate water after being sprayed onto the surface of the rotary kiln cylinder, some solid polyaluminum will adhere to the outer surface of the rotary kiln, so it is necessary to clean the adhered material on the surface. The cleaning scraper used in this device is pressed by a spring. After the cleaning scraper scrapes off the material, it will be collected through the receiving chute arranged below the rotary kiln, and then the material will be sent to the temporary storage bin through the conveying device. The spring can make the cleaning scraper always abut against the outer wall of the rotary kiln, ensuring a certain tension, so as to ensure the cleaning effect.

[0053] The concentration of hydrochloric acid required in the reaction kettle is 10%. The hydrochloric acid stock solution and water are accurately added through the electromagnetic valve supporting the flow meter to reach the concentration of hydrochloric acid required in the reaction kettle; the reaction temperature of the reaction kettle is 105-110 °C, and the temperature of the solution in the reaction kettle is accurately controlled by the temperature sensor and the PID control steam pipeline valve.

[0054] The rotary kiln uses coal or natural gas as fuel, and the whole rotary kiln is heated through a multi-channel burner. The temperature in the firing section reaches about 1200 degrees Celsius, and the flue gas temperature at the kiln tail is as high as 600 degrees Celsius, and the flow rate is about 40000 Nm 3 / h. This process uses a flue-type waste heat steam boiler. Water or steam flows in the pipeline, and flue gas flows in the flue outside the heating tubes. The flue gas transfers heat to the water or steam in the tube by scouring the outer surface of the tubes.

[0055] In the flue of the flue-type waste heat steam boiler, components such as a preheater, superheater, evaporator, economizer, steam drum, riser tube, and downcomer can also be arranged in the flue. All the heating surface components of the flue-type waste heat steam boiler are vertically arranged. Feed water enters the economizer to absorb heat and then enters the steam drum. The steam drum is connected to the lower box of the evaporator by a downcomer. The downcomer is located outside the flue and does not absorb the heat of the flue gas. The steam drum is connected to the upper header of the evaporator, and the vertical tubes of the evaporator are connected. The vertical tubes absorb the heat of the flue gas. When water absorbs the heat of the flue gas, part of the water turns into water vapor. Since the density of steam is much smaller than that of water, the average density of the steam-water mixture in the vertical tubes is less than the density of the water in the downcomer. The pressure difference between the two forms the water circulation. The water in the non-heating downcomer is heavier and flows downward; the steam-water mixture in the vertical tubes of the evaporator flows upward, which forms a continuous gas production process. At this time, the water in the waste heat boiler will naturally circulate. Without an external water pump, it will also automatically adjust the water circulation speed according to the change of the gas production volume to ensure the safe operation of the boiler. The generated steam is reheated by the high-temperature flue gas in the flue again when it is discharged through the pipeline, so that the temperature of the steam is increased again, thus meeting the requirements of the subsequent process.

[0056] The present invention uses a waste heat steam boiler to utilize the heat in the recovered kiln tail flue gas to produce steam, reducing the temperature of the kiln tail flue gas while recovering and utilizing the heat therein, and using the rotary kiln body to replace the drying tower to dry the polyaluminum solution to recover the heat of the rotary kiln body.

[0057] The embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments.

Claims

1. The combined production process of calcium aluminate powder and polyaluminum, characterized in that: Spray the polyaluminum solution onto the outer wall of the rotary kiln, and use the radiant heat of the rotary kiln body to dry the polyaluminum solution to obtain solid polyaluminum. The rotary kiln is used for the calcination process in the production of calcium aluminate powder; Collect the tail gas from the rotary kiln into the waste heat steam boiler. The waste heat steam boiler uses the waste heat in the tail gas to generate steam, and the steam is introduced into the reaction kettle for reaction heating. The reaction kettle is used for the reaction of calcium aluminate powder and hydrochloric acid to generate polyaluminum liquid, and the polyaluminum liquid is subjected to solid-liquid separation to obtain polyaluminum solution; The tail gas from the rotary kiln enters the tail gas treatment device after being cooled by the waste heat steam boiler; An acid mist absorption tower is arranged on the reaction kettle to absorb the acidic components in the polyaluminum liquid; The polyaluminum solution is sprayed onto the firing section of the rotary kiln. The outer wall temperature of the firing section of the rotary kiln is 240-300 °C, the rotation speed of the rotary kiln is 0.5-4.3 r / min, and the flow rate of the polyaluminum solution is 5-11 cubic meters / h.

2. The calcium aluminate powder and polyaluminum combined production process according to claim 1, characterized in that: The rotation speed of the rotary kiln is 3.2-4.3 r / min.

3. The calcium aluminate powder and polyaluminum combined production process according to claim 1, wherein: The steam temperature generated by the waste heat steam boiler is 160 °C, and the steam flow rate is 9 T / h.

4. Calcium aluminate powder and polyaluminum combined production device, characterized in that: Applicable to the production process described in any one of claims 1 to 3, including a rotary kiln, a waste heat steam boiler, a reaction kettle, a plate and frame filter press, and a liquid storage tank. The tail gas outlet of the rotary kiln is connected to the waste heat steam boiler, the steam outlet of the waste heat steam boiler is connected to the reaction kettle, the discharge port of the reaction kettle is connected to the plate and frame filter press, the discharge port of the plate and frame filter press is connected to the liquid storage tank, and the discharge port of the liquid storage tank is connected with an atomizing device through a shunt device. The atomizing device includes a conveying pipeline arranged on one side of the rotary kiln and a fan-shaped nozzle connected to the conveying pipeline, and the fan-shaped nozzle sprays towards the outer wall of the firing section of the rotary kiln; An acid mist absorption tower is arranged on the reaction kettle to absorb the acidic components in the polyaluminum liquid.

5. The calcium aluminate powder and polyaluminum combined production device according to claim 4, characterized in that: It also includes a cleaning and collection device, which includes a cleaning scraper, a receiving chute and a conveying device. The cleaning scraper abuts against the outer side wall of the rotary kiln, the receiving chute is arranged on the side of the scraper, and the conveying device is located below the receiving chute.

6. The calcium aluminate powder and polyaluminum combined production device according to claim 5, characterized in that: The bottom of the cleaning scraper is rotatably connected to the bracket, and the middle of the cleaning scraper is connected to the bracket through a spring.

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