A split-flow pulse backflush nozzle for high-temperature filters

Abstract

A split-flow pulse back-blowing nozzle for a high-temperature filter comprises an outer straight tube, an outer conical tube and an inner straight tube, wherein the bottom end of the outer straight tube is connected to the small end of the outer conical tube, the large end of the outer conical tube faces the top of the filter tube, the inner straight tube is located inside the outer straight tube and extends to the inside of the outer conical tube, the bottom end of the inner straight tube is axially aligned with the large end of the outer conical tube, a plurality of guide vanes are connected between the inner straight tube and the outer straight tube, and the gas can flow in a circumferential direction through the plurality of guide vanes, so that the gas can flow from the annular cavity between the inner straight tube and the outer straight tube in a spiral downward direction into the outer conical tube, thereby increasing the back-blowing gas flow rate, increasing the back-blowing pressure in the top area of ​​the filter tube, reducing the thermal shock impact of the back-blowing gas on the filter tube, improving the uniformity of the back-blowing pressure along the length direction of the filter tube, and suppressing the oscillation phenomenon at the open end.

Description

Technical Field

[0001] The invention relates to the field of back-flushing nozzles for filters, and in particular to a split-flow pulse back-flushing nozzle for high-temperature filters. Background Art

[0002] In the production process of many industries such as petroleum, chemical industry, metallurgy, and electric power, high-temperature dust-laden gas is usually generated. In order to meet different process requirements, or to recover waste heat or meet environmental emission standards, it is necessary to purify the high-temperature gas in the process. At present, filtration technology is the most widely used in the field of gas-solid separation. It has the characteristics of high separation efficiency and can completely remove particles larger than 5 μm. The gas concentration after purification is less than 5 mg / m 3 High-temperature filter media are mainly ceramic porous materials and metal porous materials. With the development of material science and preparation technology, high-temperature filter elements have good mechanical properties, thermal shock resistance and corrosion resistance, and have been widely used.

[0003] High-temperature filters are usually equipped with dozens to thousands of filter tubes. A group of filter tubes share a pulse backflushing system. The filter tubes are arranged in rows and columns with equal spacing on the tube plate. The dust-laden gas enters the filter from the inlet. When the gas flows through the filter tube and enters the tube, the dust particles will be captured by the wall of the filter tube. The purified gas flows upward along the tube and enters the clean air chamber from the top, and then is discharged from the outlet to complete the purification. The dust particles captured on the surface of the filter tube will continue to accumulate and gradually form a dust layer. When the dust layer reaches a certain thickness, due to the high gas flow resistance, it is necessary to use pulse backflushing to remove the surface deposited dust. High-pressure gas enters the backflushing pipeline and is ejected from the pulse nozzle. The backflushing airflow enters the filter tube and the surface deposited dust is removed by the pulse countercurrent gas, realizing the recycling regeneration of the filter element, thereby ensuring the continuous, stable and efficient operation of the filter process. Therefore, the pulse backflushing cleaning technology seriously affects the service life and reliability of the filter element.

[0004] The commonly used nozzle structures are usually divided into two types: straight tube type and tapered type. However, during the long-term actual operation of the filter using the existing nozzle structure, the residual dust layer is usually unevenly distributed along the axial direction. The amount of residual dust at the top is relatively large. In severe cases, dust bridging will occur, that is, a dust connection structure will be formed between the two filter tubes. On the one hand, it will affect the gas flow resistance and effective filtration area of ​​the filter tube. On the other hand, the combined effect of dust bridging and thermal shock caused by pulsed cold air flow will cause the filter tube to break at the top position, causing the filter to fail. The root cause of the above problem is that the back-blowing gas jet characteristics are not ideal, resulting in serious unevenness in the dynamic pressure peak in the filter tube, causing uneven cleaning effect, while the dynamic pressure peak at the open end of the filter tube is significantly smaller, and there is a significant oscillation phenomenon in the back-blowing pressure, resulting in continuous deposition of dust on the top of the filter tube to form bridges, and even causing the filter tube to break. Summary of the Invention

[0005] The purpose of the present invention is to provide a split-flow pulse backflush nozzle for high-temperature filters.

[0006] 14. The smoke filter according to claim 13, wherein the filter comprises a filter element and a filter element, wherein the filter element has a plurality of filter elements, each of which has a plurality of filter elements. The filter element has a plurality of filter elements, and the filter element has a plurality of filter elements. The filter element has a plurality of filter elements, and the filter element has a plurality of filter elements. The filter element has a plurality of filter elements, and the filter element has a plurality of filter elements.

[0007] The back-blowing nozzle comprises an outer straight tube, an outer conical tube and an inner straight tube. The top of the outer straight tube is connected to the side wall of the back-blowing tube, the bottom end of the outer straight tube is connected to the small end of the outer conical tube, the large end of the outer conical tube faces the top of the filter tube, the inner straight tube is located inside the outer straight tube and extends to the inside of the outer conical tube, the axes of the inner straight tube, the outer straight tube and the outer conical tube are arranged to coincide with each other, the bottom end of the inner straight tube is aligned with the large end of the outer conical tube along the axial direction, and a plurality of guide blades are provided between the inner straight tube and the outer straight tube. The two sides of the guide blades in the width direction are respectively connected to the outer wall of the inner straight tube and the inner wall of the outer straight tube, and the plurality of guide blades are evenly spaced along the circumferential direction of the inner straight tube, and the bottom end of the guide blades extends to the bottom end of the outer straight tube. The bottom ends of the plurality of guide blades are biased to the same side relative to the top end thereof in the circumferential direction. The gas can flow in the circumferential direction through the plurality of guide blades, so that the gas can flow from the annular cavity between the inner straight tube and the outer straight tube in a spiral downward direction into the outer conical tube.

[0008] Preferably, the back-blowing gas source is a gas storage tank, and a solenoid valve is connected between the gas storage tank and the back-blowing pipe.

[0009] Preferably, a smooth transition guide cambered surface is formed between the top and bottom ends of the guide blade.

[0010] Preferably, a plurality of circular or rectangular vent holes are provided on the outer cone tube.

[0011] According to the above technical solution, the beneficial effects of the present invention are:

[0012] The present invention can divide the pulse back-blowing gas into two jets, an inner and an outer jet, through the double-layer structure of the outer straight tube and the inner straight tube. The inner jet is in the form of a direct current and is directly injected into the filter tube, while the outer jet passes through the guide vane to form a swirl flow and enters the filter tube in a rotating manner. Since the external jet is a rotating flow, its flow path is significantly extended relative to the direct current jet, which increases the residence time of the high-pressure back-blowing jet at the top of the filter tube, thereby increasing the back-blowing pressure and pressure duration at the top of the filter tube, and effectively solves the oscillating backflow problem at the open end. Therefore, the internal jet mainly acts on the back-blowing cleaning of the middle and lower part of the filter tube, while the external jet mainly acts on the back-blowing cleaning of the top of the filter tube, effectively improving the uniformity of the cleaning and preventing dust bridging at the top of the filter tube.

[0013] The present invention can increase the back-blowing gas flow rate, improve the back-blowing pressure in the top area of ​​the filter tube, reduce the thermal shock impact of the back-blowing gas on the filter tube, improve the uniformity of the back-blowing pressure along the length direction of the filter tube, and suppress the oscillation phenomenon at the open end. The external rotating jet ejected from the nozzle can suck more high-temperature gas in the clean air chamber compared to the straight-flow gas. On the one hand, the flow rate of the back-blowing gas is increased, which can improve the back-blowing effect; on the other hand, the more high-temperature gas sucked in and the stronger airflow disturbance ability of the swirl itself can more effectively increase the temperature of the back-blowing gas, reduce the temperature difference with the filter tube, and thus reduce the thermal shock effect on the filter tube caused by the temperature difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of a high temperature filter;

[0015] Figure 2 Schematic diagram of the structure of the back-blowing nozzle;

[0016] Figure 3 The distribution of the peak dynamic pressure in the filter tube along the length direction;

[0017] Figure 4 is the dynamic pressure at the open end of the filter tube.

[0018] Markings in the figure: 1. External straight pipe, 2. Internal straight pipe, 3. External tapered pipe, 4. Guide vane, 5. Filter housing, 6. Tube sheet, 7. Filter air chamber, 8. Clean air chamber, 9. Air inlet, 10. Air outlet, 11. Filter tube, 12. Backflush tube, 13. Air storage tank, 14. Solenoid valve, 15. Backflush nozzle. DETAILED DESCRIPTION

[0019] With reference to the accompanying drawings, the specific implementation is as follows:

[0020] A split-flow pulse back-flushing nozzle for a high-temperature filter, wherein the high-temperature filter is Figure 1 As shown, it includes a filter housing 5, in which a tube sheet 6 is installed. The tube sheet 6 divides the inner cavity of the filter housing 5 into a filter air chamber 7 on the lower side and a clean air chamber 8 on the upper side. The side wall of the filter housing 5 is provided with an air inlet 9 for the dust-laden gas to flow into the filter air chamber 7, and an air outlet 10 for the filtered gas to flow out of the clean air chamber 8. A plurality of filter tubes 11 are provided in the filter air chamber 7, and one or more backflush tubes 12 are provided in the clean air chamber 8.

[0021] like Figure 1As shown, the top ends of multiple filter tubes 11 are all installed on the tube sheet 6, so that the dust-laden gas is filtered and then passes through the tube sheet 6 into the clean air chamber 8. The backflush pipe 12 extends to the outside of the filter housing 5 and is connected to the gas storage tank 13. A solenoid valve 14 is connected between the gas storage tank 13 and the backflush pipe 12. A plurality of backflush nozzles 15 are connected to the side wall of the backflush pipe 12. All the backflush nozzles 15 correspond to the top ends of the multiple filter tubes 11 one by one. When the solenoid valve 14 is opened, the backflush airflow can be blown into the multiple filter tubes 11 respectively through the multiple backflush nozzles 15.

[0022] like Figure 2 As shown, the backblowing nozzle 15 includes an outer straight tube 1, an outer conical tube 3 and an inner straight tube 2. The top end of the outer straight tube 1 is connected to the side wall of the backblowing tube 12, the bottom end of the outer straight tube 1 is connected to the small end of the outer conical tube 3, the large end of the outer conical tube 3 faces the top end of the filter tube 11, the inner straight tube 2 is located inside the outer straight tube 1 and extends to the inside of the outer conical tube 3. The axes of the inner straight tube 2, the outer straight tube 1 and the outer conical tube 3 are arranged to coincide with each other, and the bottom end of the inner straight tube 2 is aligned axially with the large end of the outer conical tube 3.

[0023] like Figure 2 As shown, a plurality of guide vanes 4 are provided between the inner straight tube 2 and the outer straight tube 1. The two sides of the guide vanes 4 in the width direction are respectively connected to the outer wall of the inner straight tube 2 and the inner wall of the outer straight tube 1. The plurality of guide vanes 4 are evenly spaced along the circumferential direction of the inner straight tube 2. The bottom ends of the guide vanes 4 extend to the bottom end of the outer straight tube 1. The bottom ends of the plurality of guide vanes 4 are biased to the same side relative to the top ends thereof along the circumferential direction. The plurality of guide vanes 4 can cause the gas to flow in the circumferential direction, so that the gas can flow from the annular cavity between the inner straight tube 2 and the outer straight tube 1 into the outer conical tube 3 in a spiral downward direction.

[0024] In this embodiment, the ratio of the diameter of the inner straight tube 2 to the diameter of the outer straight tube 1 is 1:1.1~1:2.5, the height of the inner straight tube 2 is higher than the sum of the heights of the guide blades 4 and the outer conical tube 3, the number of guide blades 4 is 4~12, and the height of the guide blades 4 is 10~100 mm.

[0025] The blade type of the guide blade 4 can be a straight spiral, an ellipse, a circular arc, an inclined flat plate, and an airfoil. In this embodiment, the top and bottom ends of the guide blade 4 are connected by a smoothly transitioned guide arc surface, the blade outlet angle is 5~70°, the blade wrap angle is 30~90°, and the tops of the inner straight tube 2 and the guide blade 4 are both sharpened.

[0026] In this embodiment, the height of the outer cone tube 3 is set to 5-100 mm, the angle between the busbar and the axis is 5-70°, and a plurality of circular or rectangular air holes are provided on the outer cone tube 3, which can enhance the suction effect of the spiral airflow.

[0027] In this embodiment, the wall thickness of the outer straight tube 1, the inner straight tube 2, the guide vane 4 and the outer conical tube 3 is set to 0.5~4 mm, and the material of the outer straight tube 1, the inner straight tube 2, the guide vane 4 and the outer conical tube 3 are all metal materials such as stainless steel.

[0028] Performance test: The diameter of the outer straight tube 1 is set to 12 mm, and the diameter of the inner straight tube 2 is set to 9.5 mm; the number of guide blades 4 is set to 8, the total height is set to 14 mm, the blade outlet angle is set to 27°, the blade wrap angle is set to 60°, and the blade type is arc type; the height of the inner straight tube is 30 mm; the height of the expansion cone 3 is set to 10 mm, the angle between its generatrix and the axis is set to 25°, and the holes opened are rectangular holes (width 1.5 mm, height 5 mm, 6 evenly arranged).

[0029] The nozzle's backflushing performance was tested using a metal filter tube with an outer diameter of 60 mm, an inner diameter of 50 mm, and a length of 2000 mm. Pulse backflushing was performed online, with a superficial velocity of 2 m / min, a backflushing pressure of 0.5 MPa, a pulse width of 150 ms, and a distance of 50 mm between the nozzle bottom and the filter tube top.

[0030] The peak backflush pressure test results along the length of the filter tube are as follows: Figure 3 As shown in the figure, the use of the nozzle of the present invention can significantly improve the uniformity of the back-flushing pressure. The peak pressure at the filter tube opening is increased to 8.12 kPa, and the difference between the peak pressures at the blind end and the open end of the filter tube is reduced to 1.29 kPa, which significantly improves the uniformity of back-flushing cleaning, thereby improving the filtration cycle performance of the filter. The dynamic back-flushing pressure test results at the filter tube opening are shown in the figure. Figure 4 As shown, it can be seen that there is no oscillation phenomenon, which helps to suppress dust bridging and reduce the exciting force on the filter tube, thereby extending the service life of the filter tube.

Claims

1. A split-flow pulse back-flushing nozzle for a high-temperature filter, the high-temperature filter comprising a filter housing (5), a tube sheet (6) installed in the filter housing (5), the tube sheet (6) dividing the inner cavity of the filter housing (5) into a filter air chamber (7) on the lower side and a clean air chamber (8) on the upper side, an air inlet (9) for allowing dust-laden gas to flow into the filter air chamber (7), and an air outlet (10) for allowing filtered gas to flow out of the clean air chamber (8), a plurality of filter tubes (11) are provided in the filter air chamber (7), and the clean air chamber (8) is provided with a plurality of filter tubes (11) in the filter air chamber (7). (8) is provided with one or more back-blowing pipes (12), and the top ends of the plurality of filter tubes (11) are all installed on the tube sheet (6) so that the dust-laden gas is filtered and then flows through the tube sheet (6) into the clean air chamber (8). The back-blowing pipe (12) extends to the outside of the filter housing (5) and is connected to the back-blowing gas source. The side wall of the back-blowing pipe (12) is connected to a plurality of back-blowing nozzles (15), and all the back-blowing nozzles (15) correspond to the top ends of the plurality of filter tubes (11) one by one, so that the back-blowing air flow can be blown into the plurality of filter tubes (11) through the plurality of back-blowing nozzles (15). Its characteristics are: The back-blowing nozzle (15) comprises an outer straight tube (1), an outer conical tube (3) and an inner straight tube (2), wherein the top end of the outer straight tube (1) is connected to the side wall of the back-blowing tube (12), the bottom end of the outer straight tube (1) is connected to the small end of the outer conical tube (3), the large end of the outer conical tube (3) faces the top end of the filter tube (11), the inner straight tube (2) is located inside the outer straight tube (1) and extends to the inside of the outer conical tube (3), the axes of the inner straight tube (2), the outer straight tube (1) and the outer conical tube (3) are arranged to coincide with each other, the bottom end of the inner straight tube (2) and the large end of the outer conical tube (3) are aligned along the axial direction, and a plurality of guide vanes (4) are provided between the inner straight tube (2) and the outer straight tube (1). The two sides of the blade (4) in the width direction are respectively connected to the outer wall of the inner straight tube (2) and the inner wall of the outer straight tube (1); the plurality of guide blades (4) are evenly spaced along the circumferential direction of the inner straight tube (2); the bottom ends of the guide blades (4) extend to the bottom end of the outer straight tube (1); the bottom ends of the plurality of guide blades (4) are biased toward the same side relative to the top ends thereof along the circumferential direction; the plurality of guide blades (4) can cause the gas to flow in the circumferential direction, thereby allowing the gas to flow from the annular cavity between the inner straight tube (2) and the outer straight tube (1) into the outer conical tube (3) in a spiral downward direction; and the outer conical tube (3) is provided with a plurality of circular or rectangular vents.

2. A split-flow pulse backflush nozzle for a high-temperature filter according to claim 1, characterized in that: The back-blowing gas source is an air storage tank (13), and a solenoid valve (14) is connected between the air storage tank (13) and the back-blowing pipe (12).

3. The split-flow pulse backflush nozzle for a high-temperature filter according to claim 1, characterized in that: A smooth transitional guide cambered surface is formed between the top and bottom ends of the guide blade (4).

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