Feed system, rotary kiln system for producing hydrogen fluoride

Abstract

The application belongs to the technical field of hydrogen fluoride synthesis, and discloses a feeding system and a rotary kiln system for producing hydrogen fluoride, which comprises, in sequence, a powder storage tank, a powder conveyor and a horizontal mixer; the horizontal mixer is provided with a power mechanism for pushing the material in the horizontal mixer forward into the rotary kiln; a liquid input pipe is arranged on the horizontal mixer; a first valve is arranged on the discharge port of the powder storage tank; a second valve is arranged on the discharge port of the powder conveyor; a third valve is arranged on the liquid input pipe; and a first sensor for detecting whether there is material in the discharge port of the powder conveyor is arranged on the discharge port of the powder conveyor. The system is provided with valves on the feeding end and the discharge end of the powder conveyor, and the liquid input pipe is also provided with a valve; the three valves act in sequence according to the signal of the first sensor, so that the powder conveyor can be closed in time, corrosion can be avoided, accurate solid-liquid proportioning can be realized, the material control precision can be improved, and the atmosphere in the rotary kiln can be effectively prevented from entering the powder conveyor, further reducing corrosion. Meanwhile, the utility model also provides a rotary kiln system for producing hydrogen fluoride.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen fluoride synthesis technology, and in particular to a feeding system and a rotary kiln system for producing hydrogen fluoride. Background Technology

[0002] Patent application with publication number EP1167286A2, which describes a process for producing hydrogen fluoride using a rotary kiln, describes a process for producing hydrogen fluoride by reacting fluorite with sulfuric acid, in which the heat generated by combustion is used to react the raw materials.

[0003] Our company generally uses this process for production; there are generally no problems when carrying out continuous production, but we face some more difficult problems when carrying out intermittent production.

[0004] In intermittent production, fluorite powder is generally fed in batches. Several issues must be addressed when feeding it in a single batch:

[0005] 1. The timing of the mixing termination of sulfuric acid and powder cannot be accurately determined, making it difficult to achieve a precise solid-liquid ratio;

[0006] 2. Continuous addition of sulfuric acid can cause sulfuric acid to flow back into the silo or the screw feeder for powder feeding;

[0007] 3. After the material in the feeding mechanism is emptied, the HF atmosphere and the gas generated by sulfuric acid in the rotary kiln will flow back to the screw feeder, causing severe corrosion. Utility Model Content

[0008] The purpose of this invention is to provide a rotary kiln feeding system. This system has valves installed at both the feed and discharge ends of the powder conveyor, and a valve installed on the liquid input pipe. The three valves operate sequentially based on the signal from the first sensor, which can achieve timely closure of the powder conveyor to prevent corrosion. At the same time, it can achieve precise solid-liquid mixing, improve material control accuracy, and effectively reduce the amount of atmosphere inside the rotary kiln entering the powder conveyor, further reducing corrosion.

[0009] In addition, this utility model also provides a rotary kiln system for producing hydrogen fluoride.

[0010] To achieve the above objectives, this application discloses a rotary kiln feeding system, comprising a powder storage tank, a powder conveyor, and a horizontal mixer connected in sequence; the horizontal mixer has a power mechanism for pushing the material in the horizontal mixer forward into the rotary kiln; the horizontal mixer is provided with a liquid input pipe; the discharge port of the powder storage tank is provided with a first valve; the discharge port of the powder conveyor is provided with a second valve; the liquid input pipe is provided with a third valve; the discharge port of the powder conveyor is provided with a first sensor for detecting whether there is material at the discharge port of the powder conveyor;

[0011] The first valve, the second valve, and the third valve close sequentially based on the signal from the first sensor.

[0012] In the aforementioned rotary kiln feeding system, the powder conveyor is a screw conveyor; the screw conveyor is axially arranged with multiple second sensors for detecting the position of the material inside the screw conveyor; the first valve closes based on the signal from the second sensor, and the second valve closes based on the signal from the first sensor.

[0013] In the aforementioned rotary kiln feeding system, both the first sensor and the second sensor are radar sensors.

[0014] In the aforementioned rotary kiln feeding system, the power mechanism of the horizontal mixer is a screw mechanism or a ribbon mechanism, or the horizontal mixer is a rotary horizontal mixer with a spiral guide plate on the inner wall.

[0015] In the aforementioned rotary kiln feeding system, the power mechanism of the horizontal mixer is a screw mechanism;

[0016] The horizontal mixer has a three-section cylindrical structure; the horizontal mixer includes a feeding section, a connecting section, and a discharging section connected in sequence; the discharge port of the powder conveyor is connected to the feeding section; the discharging section is connected to the rotary kiln; and the liquid input pipe is connected to the discharging section.

[0017] In the aforementioned rotary kiln feeding system, the discharge port of the powder conveyor is equipped with a buffer chamber located above the second valve; the buffer chamber has a cavity structure that is wider at the top and narrower at the bottom.

[0018] In the aforementioned rotary kiln feeding system, the combination of multiple cross-sectional profiles of the buffer chamber from top to bottom forms an eccentric circle.

[0019] In the aforementioned rotary kiln feeding system, both the first valve and the second valve are knife gate valves.

[0020] Meanwhile, this utility model also discloses a rotary kiln system for producing hydrogen fluoride, including a rotary kiln and a rotary kiln feeding system as described above, wherein the outlet of the horizontal mixer is connected to the inlet of the rotary kiln.

[0021] In the rotary kiln system described above, the powder storage tank is used to store fluorite powder, and the liquid input pipe is used to input sulfuric acid.

[0022] The beneficial effects of this application are:

[0023] 1. This solution uses a horizontal mixer combined with a liquid inlet pipe. The horizontal mixer continuously pushes the material and the liquid inlet pipe simultaneously replenishes the liquid (such as sulfuric acid), which can achieve a more precise mixing ratio of solid and liquid, thereby improving the accuracy of material proportioning in the rotary kiln.

[0024] 2. This solution uses the first valve, second valve, and third valve in conjunction with the first sensor to achieve the sequential closing of the first valve, second valve, and third valve. This can prevent liquids (such as sulfuric acid) from flowing back to the powder conveyor, while also improving the accurate solid-liquid mixing ratio of the last material. In addition, it can reduce the backflow of atmosphere from the rotary kiln to the powder conveyor and horizontal mixer.

[0025] 3. In some preferred embodiments of this utility model, the closing accuracy of the first valve can be further improved by setting more sensors.

[0026] 4. In some preferred embodiments of this utility model, by optimizing the valve settings, the sealing effect on the gas can be improved, and the corrosiveness of the gas to the equipment can be further reduced. Attached Figure Description

[0027] Figure 1 The diagrams are schematic diagrams of the structures of Examples 1 and 2. Detailed Implementation

[0028] The present invention will now be clearly and completely described in conjunction with its embodiments. It should be noted that, in this description, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0029] Example 1

[0030] refer to Figure 1 A rotary kiln feeding system includes a powder storage tank 1, a powder conveyor 2, and a horizontal mixer 3 connected in sequence. The horizontal mixer 3 has a power mechanism 4 for pushing the material in the horizontal mixer 3 forward into the rotary kiln 15. The horizontal mixer 3 is provided with a liquid input pipe 5. The discharge port of the powder storage tank 1 is provided with a first valve 6. The discharge port of the powder conveyor 2 is provided with a second valve 7. The liquid input pipe 5 is provided with a third valve 8. The discharge port of the powder conveyor 2 is provided with a first sensor 9 for detecting whether there is material at the discharge port of the powder conveyor 2.

[0031] The first valve 6, the second valve 7, and the third valve 8 close sequentially based on the signal from the first sensor 9.

[0032] In this embodiment, the discharge port of the horizontal mixer 3 is directly connected to the feed end of the rotary kiln 15; the powder storage tank 1 stores fluorite powder; in this embodiment, the powder conveyor 2 is a screw conveyor; the screw conveyor refers to a feeding device with an auger and driven by a motor. In practical applications, it can also be other devices, such as a belt conveyor or a chute installed in a closed pipeline; however, in terms of feeding accuracy, a screw conveyor is preferred.

[0033] The working principle of this embodiment is as follows:

[0034] The powder storage tank 1 continuously feeds the material into the powder conveyor 2. The powder in the powder storage tank 1 can be discharged to the powder conveyor 2 by falling under its own weight, or a vertically arranged auger can be installed in the powder storage tank 1 to improve the smoothness of the powder entering the powder conveyor 2. The powder conveyor 2 continuously feeds the powder into the horizontal mixer 3. The power mechanism 4 of the horizontal mixer 3 continuously pushes the material forward. At a specific position of the horizontal mixer 3, liquid material is added through the liquid input pipe 5 to achieve the mixing of solid and liquid in proportion.

[0035] To address the problems in existing technologies, such as inaccurate tailing ratios, easy backflow of liquid materials, and easy escape of gas into the powder conveyor 2 or even the powder storage tank 1, this embodiment adds a first valve 6, a second valve 7, a third valve 8, and a first sensor 9. Implicitly, this embodiment requires a controller or microcontroller to write preset control programs for the first valve 6, second valve 7, and third valve 8. Taking the rotary kiln 15 feeding system used in HF production as an example, the powder is fluorite powder, and the liquid is sulfuric acid; it is necessary to pre-calculate the... When the first sensor 9 detects no material (set this time as T0), the first valve 6 closes; from T0 to T1, the second valve 7 closes; from T1 to T2, the third valve 8 closes. Thus, the first valve 6 closes immediately after the first sensor 9 detects no material; the second valve 7 closes at time T1, and the third valve 8 closes at time T2. Of course, the above-mentioned T1 and T2 recommendations are not only based on calculations but should also be tested to calibrate T1 and T2, and the calibrated T1 and T2 should be used as parameters written into the control program. In actual production, the time interval from T0 to T1 is set according to the height of the first sensor 9 at the outlet of the powder conveyor 2. The first sensor 9 is a certain distance from the second valve 7. The material discharge speed is 0.1 kg / s. The volume between the position of the first sensor 9 and the position of the second valve 7 in the outlet is 1 kg. Therefore, the time interval from T0 to T1 is 10 seconds. The time interval from T1 to T2 is related to the position of the liquid input pipe 5. It is necessary to calculate how long it takes for the material from the outlet of the powder conveyor 2 to reach the position of the liquid input pipe 5 at time T1. Assuming it is 20 seconds, the time interval from T1 to T2 is 20 seconds. Through the above design, the accuracy of material proportioning can be improved and liquid and gas backflow can be prevented.

[0036] Preferably, the screw conveyor is axially arranged with a plurality of second sensors 10 for detecting the position of the material inside the screw conveyor; the first valve 6 closes the valve according to the signal of the second sensor 10, and the second valve 7 closes the valve according to the signal of the first sensor 9.

[0037] When the second sensor 10 is present, the action of the first valve 6 is adjusted. The second sensor 10 will be the first to detect that there is no material input in the screw conveyor. At this time, the first valve 6 closes. Multiple second sensors 10 continuously monitor the remaining material in the screw conveyor and transmit this data to the control room to remind the operator that the material is about to be emptied. The second valve 7 still operates according to the signal of the first sensor 9.

[0038] Preferably, both the first sensor 9 and the second sensor 10 are radar sensors. In this field, there are many types of sensors for detecting the amount of material, such as optical sensors (based on emitting infrared or laser beams and determining the presence or absence of material by receiving the intensity of reflected light) and ultrasonic level sensors (non-contact measuring devices based on the principle of echo ranging). In practical applications, the appropriate sensor can be flexibly selected based on cost, production environment, etc.

[0039] More preferably, the power mechanism 4 of the horizontal mixer 3 is a screw mechanism or a ribbon mechanism, or the horizontal mixer 3 is a rotary horizontal mixer 3 with a spiral guide plate on the inner wall.

[0040] In this embodiment, the power mechanism 4 adopts a screw mechanism (i.e., the auger as described above). The advantage of using a screw mechanism is that the material delivery is more accurate, which is conducive to the precise mixing of solid and liquid in proportion. Generally speaking, the ribbon mechanism is more suitable for the processing of Chinese herbal medicines and the mixing of liquid as the main component. If it is applied to this embodiment, its material delivery accuracy will be reduced.

[0041] In this embodiment, the horizontal mixer 3 has a three-section cylindrical structure; the horizontal mixer 3 includes a feeding section 11, a connecting section 12, and a discharging section 13 connected in sequence; the discharge port of the powder conveyor 2 is connected to the feeding section 11; the discharging section 13 is connected to the rotary kiln 15; the liquid input pipe 5 is connected to the discharging section 13. The feeding section 11, connecting section 12, and discharging section 13 are all connected by flanges, implicitly, an annular sealing gasket is provided at the flange interface; more preferably, the feeding section 11, connecting section 12, and discharging section 13 are all fixed on a base. The advantage of the above three-section design is that it facilitates maintenance and replacement. According to actual production conditions, the section closer to the rotary kiln 15 has a higher probability of corrosion, and the frequency of maintenance and replacement is also higher. Based on this practical need, the above three-section design is adopted.

[0042] Preferably, the discharge port of the powder conveyor 2 is provided with a buffer chamber 14 located above the second valve 7; the buffer chamber 14 is a cavity structure with a thicker upper part and a thinner lower part, and the combination of multiple cross-sectional profiles of the buffer chamber 14 from top to bottom forms an eccentric circle.

[0043] When viewed from above, the buffer chamber 14 has multiple cross-sections forming an eccentric circle, while from the axial section, the buffer chamber 14 is trapezoidal.

[0044] In the preferred design, the first sensor 9 is installed inside the buffer chamber 14 to detect the height of the material. When the material in the buffer chamber 14 is below the lower limit, the first valve 6 can be controlled to close immediately and the second valve 7 can be controlled to close after a delay.

[0045] In addition, the buffer chamber 14 can disperse the material output from the powder conveyor 2, which has been compressed into a single piece, in a larger space, facilitating its smooth entry into the horizontal mixer 3. At the same time, the buffer chamber 14 is connected to the discharge port of the powder conveyor 2 and the second valve 7 by a flange, which is a detachable structure, facilitating the cleaning of residual powder when the machine is shut down for a long time.

[0046] In this embodiment, the first valve 6 and the second valve 7 are preferably pneumatic knife gate valves. Knife gate valves are also known as knife gate valves, slurry valves, or mud valves. Their opening and closing element is a gate, and the gate has two sealing surfaces. The most commonly used gate valve has two sealing surfaces that form a wedge shape or wedge angle. This wedge angle design has a better sealing effect and is particularly suitable for the process scenarios in this embodiment that generate gas. In practical applications, it is not limited to pneumatic knife gate valves. Electric knife gate valves, hydraulic knife gate valves, bevel gear or sprocket knife gate valves can also be used in this embodiment.

[0047] Example 2

[0048] refer to Figure 1 A rotary kiln system for producing hydrogen fluoride includes a rotary kiln 15 and a rotary kiln 15 feeding system as described in Example 1, wherein the outlet of the horizontal mixer 3 is connected to the inlet of the rotary kiln 15; the powder storage tank 1 is used to store fluorite powder, and the liquid input pipe 5 is used to input sulfuric acid.

[0049] Its production process (taking HF's intermittent production as an example) is as follows:

[0050] The powder storage tank 1 continuously feeds the material into the powder conveyor 2, which in turn continuously feeds the powder into the horizontal mixer 3. The opening of the second valve 7 is controlled according to a pre-defined metering ratio, so that the liquid (sulfuric acid) output from the liquid input pipe 5 and the powder (fluorite powder) are mixed in a preset ratio (1.18:1). After mixing, the mixture continues to move along the horizontal mixer 3 until it enters the rotary kiln 15. The material is heated in the rotary kiln 15 to generate HF (this process can refer to existing technology).

[0051] When production is nearing completion, the first valve 6 is immediately closed after the first sensor 9 detects that the material has been discharged, the second valve 7 is closed at time T1, and the third valve 8 is closed at time T2. In this embodiment, based on calculations and actual measurements, T1 is 10s and T2 is 30s.

[0052] Through the above optimizations, the system of the present invention can achieve the following effects:

[0053] 1. Reduced material residue;

[0054] 2. Equipment corrosion rate decreased by 40%;

[0055] 3. The solid-liquid ratio control accuracy reaches ±0.5%, the product qualification rate is increased by 15%, and the annual raw material waste is reduced.

Claims

1. A rotary kiln feeding system, connected to a rotary kiln, characterized in that, The system includes a powder storage tank, a powder conveyor, and a horizontal mixer connected in sequence. The horizontal mixer has a power mechanism for pushing the material in the horizontal mixer forward into a rotary kiln. The horizontal mixer is equipped with a liquid inlet pipe. The outlet of the powder storage tank is equipped with a first valve. The outlet of the powder conveyor is equipped with a second valve. The liquid inlet pipe is equipped with a third valve. The outlet of the powder conveyor is equipped with a first sensor for detecting whether there is material at the outlet of the powder conveyor. The first valve, the second valve, and the third valve close sequentially based on the signal from the first sensor.

2. The rotary kiln feeding system according to claim 1, characterized in that, The powder conveyor is a screw conveyor; the screw conveyor is axially arranged with multiple second sensors for detecting the position of the material inside the screw conveyor; the first valve closes according to the signal from the second sensor, and the second valve closes according to the signal from the first sensor.

3. The rotary kiln feeding system according to claim 2, characterized in that, Both the first sensor and the second sensor are radar sensors.

4. The rotary kiln feeding system according to claim 1, characterized in that, The power mechanism of the horizontal mixer is a screw mechanism or a ribbon mechanism, or the horizontal mixer is a rotary horizontal mixer with a spiral guide plate on the inner wall.

5. The rotary kiln feeding system according to claim 4, characterized in that, The power mechanism of the horizontal mixer is a screw mechanism; The horizontal mixer has a three-section cylindrical structure; the horizontal mixer includes a feeding section, a connecting section, and a discharging section connected in sequence; the discharge port of the powder conveyor is connected to the feeding section; the discharging section is connected to the rotary kiln; and the liquid input pipe is connected to the discharging section.

6. The rotary kiln feeding system according to claim 1, characterized in that, The discharge port of the powder conveyor is equipped with a buffer chamber located above the second valve; the buffer chamber is a cavity structure that is wider at the top and narrower at the bottom.

7. The rotary kiln feeding system according to claim 6, characterized in that, The combination of multiple cross-sectional profiles of the buffer chamber from top to bottom forms an eccentric circle.

8. The rotary kiln feeding system according to any one of claims 1 to 7, characterized in that, Both the first valve and the second valve are knife gate valves.

9. A rotary kiln system for producing hydrogen fluoride, characterized in that, It includes a rotary kiln and a rotary kiln feeding system as described in any one of claims 1 to 8, wherein the outlet of the horizontal mixer is connected to the inlet of the rotary kiln.

10. The rotary kiln system according to claim 9, characterized in that, The powder storage tank is used to store fluorite powder, and the liquid input pipe is used to input sulfuric acid.

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