Oxygen Removing Device for Filling Pellet Interstices and Its Usage Method

Abstract

Pellet interstice oxygen expulsion device, based on the principle of two-step expulsion of oxygen filled in pellets, includes an upper connecting pipe, a separation cylinder, a bottom quadrangular pyramid cylinder, an outer quadrangular pyramid cylinder, a gas collecting pipe, an inner quadrangular pyramid cylinder, a middle quadrangular pyramid cylinder, and a lower connecting pipe. The side length of the top plate of the separation cylinder is 1.5 to 2 times the inner diameter of the transport pipe, the height of the top cavity of the separation cylinder is 1 to 2 times the inner diameter of the transport pipe and the negative pressure is -20 Pa to -60 Pa, and the height of the top cavity of the inner quadrangular pyramid cylinder is 1 to 2 times the inner diameter of the transport pipe. After the balloons in the top cavity of the separation cylinder are separated, the induced draft fan sucks the main filled oxygen. 50% of the clean gas forms a planar flow through the side plate of the bottom quadrangular pyramid cylinder to drive the remaining filled oxygen near the wall of the separation cylinder, and the remaining 50% of the clean gas forms a parallel flow in the top cavity of the inner quadrangular pyramid cylinder to drive the remaining filled oxygen in the center. The pellet safe transport and smelting device for hydrogen reduction smelting in iron and steel enterprises can use the present invention. The invention has safe pellet transport, stable static pressure distribution, no deflagration, and does not carry filled oxygen into the smelting furnace.

Description

Technical Field

[0001] The present invention relates to a device for removing oxygen filling in the gaps between pellets, which has the technical characteristics of removing filling oxygen in two steps, removing the main filling oxygen by suction after balloon separation, and removing the remaining filling oxygen by combining planar flow and horizontal parallel flow. The device is suitable for the safe transportation and smelting of sintered pellets for hydrogen reduction metallurgy in steel enterprises. Background Art

[0002] The carbon-neutral metallurgical technology roadmap proposed by China Baowu in 2021 includes a hydrogen reduction metallurgical process with "microwave pelletizing-anaerobic transport of pellets and hydrogen pre-reduction-blast furnace carbon smelting" as the core.

[0003] Hydrogen molecules move at the fastest speed, so they have the greatest diffusion and high thermal conductivity, which is seven times that of air. H2 has extremely strong reducing properties. At high temperatures, hydrogen can take oxygen, phosphorus, sulfur, nitrogen, chlorine, carbon, etc. from many compounds to reduce the compounds. It is this characteristic that makes H2 a reducing agent for use in steel metallurgy. Compared with traditional carbon metallurgy, hydrogen reduction metallurgy can reduce CO2 emissions from the source. Hydrogen reduction metallurgy uses H2 to replace carbon as a reducing agent and energy source, and the product is water, which can achieve zero carbon emissions (Fe2O3+3H2=2Fe+3H2O). However, the ignition energy of H2 is very small and it is easy to ignite. Even a tiny static spark can easily ignite. The flammable range of H2 in air (20℃, 101.325kPa) is 4~74.5%. The flammable range of H2 in O2 (20℃, 101.325kPa) is 4~94%. When a large number of hydrogen and oxygen molecules in the mixed gas mix, contact and are ignited, the two react rapidly and release a large amount of heat in a very short time. These gases are in a limited space. When the temperature rises rapidly, the gas expands rapidly due to the heat and rushes out of the container with an explosion sound. If the container is a closed container or the volume opening is small, the gas cannot be discharged or cannot be discharged in time, which will cause the container to explode and cause danger.

[0004] Since H2 is a flammable and explosive gas, it is difficult to use safely. Steel smelting requires high-efficiency and long-term stable production. If the smelting furnace is operated under extreme conditions of high temperature and high pressure for a long time, it is very difficult to ensure the safety of the smelting furnace equipment and employees, which does not meet the goal of metallurgical process design. Sintered pellet ore ("pellet") is commonly transported to the smelting furnace through pipelines. Without special pretreatment, the 8mm - 16mm pellets are randomly stacked in the pipelines and the smelting furnace, and the low-oxygen flue gas discharged from the sintering device and transported along with the pellets fills the gaps between the pellets. The space between the pellets in the pipelines and the smelting furnace is narrow, and the intake and exhaust are not smooth. The reliability of H2 combustion ignition is poor, which easily causes hydrogen retention. Coupled with the difficulty of combustion and smoke exhaust when the ignition conditions are met, the possibility of deflagration is extremely high. The retention of hydrogen in the pellet gaps meets the filling oxygen. When heated or a fire source intrudes, it may cause deflagration and pose a danger. That is to say, before the pellets are sent into the smelting furnace, it is necessary to remove the filling oxygen in the pellets. If the removal of the filling oxygen in the pellets is arranged in the transport pipe, the operation safety also needs to be considered to avoid the unsafe factors of deflagration in the pellet transport pipe.

[0005] Considering the strongest reducibility of H2, the on-site requirement is to remove the strongly oxidizing filling oxygen component in the filling flue gas. Both the pellet filling flue gas and the weakly oxidizing filling CO2 component (H2 + CO2 = H2O + CO) are the objects to be removed.

[0006] According to the combustion characteristics of H2, a device for removing the filling oxygen in the pellet gaps and its use method for hydrogen reduction metallurgy are developed, which can reduce the greenhouse gas emission intensity and cut the total amount in crude steel production. Summary of the Invention

[0007] Aiming at the problems that it is difficult for the filling oxygen in the pellets in the transport pipeline and the center of the smelting furnace to diffuse and flow towards the near wall, hydrogen is flammable, explosive and difficult to transport and smelt safely, etc., the present invention designs a two-step principle for removing filling oxygen based on N2 (clean gas) removing filling oxygen (target gas) and H2 (clean gas) removing filling nitrogen (target gas). The filling oxygen - pellet separation, the induced draft fan sucks the mainly filling oxygen in the top cavity of the separation cylinder, the side of the frustum cylinder is distributed with air to form a near-wall plane flow to drive the remaining filling oxygen near the wall of the separation cylinder, and the parallel flow removes the remaining filling oxygen in the center of the separation cylinder and other technical features of the device for removing the filling oxygen in the pellet gaps.

[0008] Device for removing oxygen filling in pellet gaps, mainly including an upper connecting pipe, a square-tube-shaped separation cylinder, an outer quadrangular frustum cylinder, a square-ring-shaped gas collecting pipe, an inner quadrangular frustum cylinder, a middle quadrangular frustum cylinder, a bottom quadrangular frustum cylinder and a lower connecting pipe. After the transport pipe is disconnected into upper and lower pipes, the flange of the lower pipe is connected to the lower connecting pipe, and the flange of the upper pipe is connected to the upper connecting pipe. The separation cylinder includes a square top plate, square-tube side plates and bottom quadrangular frustum cylinder side plates. A circular hole is provided at the center of the separation cylinder top plate, and the circumference of the hole is fully welded to the bottom circumference of the upper connecting pipe. The side length of the separation cylinder top plate is 1.5 - 2 times the inner diameter of the transport pipe. 1 - 4 equal-diameter exhaust holes are evenly opened on the separation cylinder top plate outside the bottom circumference of the upper connecting pipe. The bottom quadrangular frustum cylinder is arranged upside down by 180°. The small bottom side of the bottom quadrangular frustum cylinder is 0.25 - 0.75 times the inner diameter of the transport pipe. A large number of equal-diameter air holes are vertically opened on the side plates of the bottom quadrangular frustum cylinder. The side plates of the bottom quadrangular frustum cylinder, the side plates of the outer quadrangular frustum cylinder, the top ring plate of the gas collecting pipe and the side plates of the inner quadrangular frustum cylinder enclose a pressure equalizing chamber. The large bottom side of the bottom quadrangular frustum cylinder is fully welded to the small bottom side of the outer quadrangular frustum cylinder. The large bottom side of the outer quadrangular frustum cylinder is fully welded to the outer edge of the top ring plate of the gas collecting pipe. The small bottom side of the inner quadrangular frustum cylinder is fully welded to the small bottom side of the bottom quadrangular frustum cylinder. The large bottom side of the inner quadrangular frustum cylinder is fully welded to the inner edge of the top ring plate of the gas collecting pipe. The top ring plate of the gas collecting pipe is evenly provided with a large number of equal-diameter air holes. The small bottom side of the middle quadrangular frustum cylinder is fully welded to the side plate of the bottom quadrangular frustum cylinder. The distance between the parallel sides of the small bottom surface of the middle quadrangular frustum cylinder and the small bottom surface of the bottom quadrangular frustum cylinder is less than 50mm. The annular plate area between the large bottom side of the outer quadrangular frustum cylinder and the large bottom side of the middle quadrangular frustum cylinder is 50% of the area of the top ring plate of the gas collecting pipe. The lower connecting pipe is a square-to-round pipe and the inner diameter of the round pipe is equal to the inner diameter of the upper connecting pipe. The top surface of the lower connecting pipe is horizontally arranged and the four sides are fully welded to the side plates of the inner quadrangular frustum cylinder. Above the top surface of the lower connecting pipe, a large number of air holes are evenly opened on the two opposite trapezoidal plates of the side plates of the inner quadrangular frustum cylinder and the horizontal projections of the air holes do not overlap. 50% of the clean gas blown into the gas collecting pipe forms a planar flow through the air holes on the side plates of the bottom quadrangular frustum cylinder and enters the near-wall area of the separation cylinder, driving the remaining filling gas of the near-wall pellets to leave the ball bed and flow towards the exhaust holes of the separation cylinder. The remaining 50% of the clean gas forms a horizontal parallel flow in the top cavity of the inner quadrangular frustum cylinder after passing through the air holes of the two trapezoidal plates, and the parallel flow drives the remaining filling gas to flow back into the separation cylinder from the small bottom surface of the bottom quadrangular frustum cylinder.

[0009] Usage method of the device for removing oxygen filling in pellet gaps. Two-stage deoxygenation devices are used in series. The flange of the upper connecting pipe of the first-stage deoxygenation device is connected to the upstream pipe, the flange of the lower connecting pipe is connected to the upper connecting pipe of the second-stage deoxygenation device, and the flange of the lower connecting pipe is connected to the downstream pipe. Nitrogen and hydrogen are respectively introduced into the gas collecting pipes of the first and second-stage deoxygenation devices. The negative pressure in the top cavity of the separation cylinder of each deoxygenation device is -20 Pa to -60 Pa, the height of the top cavity is equal to 1 - 2 times the inner diameter of the transport pipe, the height of the ball bed does not exceed the inner diameter of the transport pipe, the height of the top cavity of the inner quadrangular frustum cylinder is equal to 1 - 2 times the inner diameter of the transport pipe, and the static pressure of the gas collecting pipe is maintained at 0.4 MPa to 0.6 MPa.

[0010] The sintered pellet safety transport and smelting site for hydrogen reduction metallurgy in iron and steel enterprises can use the present invention.

[0011] The invention features efficient transportation, efficient smelting, and safe and stable operation. The static pressure distribution in the sintered pellet transport pipe and the smelting furnace is stable, without micro-explosion or explosion, and no filled oxygen is carried into the smelting furnace. Description of the Drawings

[0012] Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 are respectively the vertical sectional view, top view, horizontal sectional view, and bottom view of the device for expelling the filled oxygen in the pellet gaps. Figures 1 to 4 In, 1 is the upper connecting pipe, 2 is the separating cylinder in the shape of a square cylinder, 3 is the outer frustum of a square pyramid cylinder, 4 is the collecting pipe in the shape of a square ring, 5 is the inner frustum of a square pyramid cylinder, 6 is the middle frustum of a square pyramid cylinder, and 7 is the lower connecting pipe. In the separating cylinder 2, 21 is the top plate, 22 is the side plate of the square cylinder, and 23 is the side plate of the bottom frustum of a square pyramid cylinder. Detailed Embodiment

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] As shown in the attached Figure 1 ~attached Figure 4 figures, the device for expelling the filled oxygen in the pellet gaps mainly includes a circular tubular upper connecting pipe 1, a square cylinder-shaped separating cylinder 2, an outer frustum of a square pyramid cylinder 3, a square ring-shaped collecting pipe 4, an inner frustum of a square pyramid cylinder 5, a middle frustum of a square pyramid cylinder 6, and a lower connecting pipe 7. The lower connecting pipe 7 is a square-to-round pipe. After the transport pipe is disconnected to become the upstream pipe and the downstream pipe, the top surface of the downstream pipe and the bottom flange of the circular pipe of the lower connecting pipe 7 are sealed and connected by flanges, and the bottom surface of the upstream pipe and the top surface of the upper connecting pipe 1 are sealed and connected by flanges. The central axes of the separating cylinder 2, the upper connecting pipe 1, and the upstream pipe are collinear and are vertically installed.

[0015] As shown in the attached Figure 2 figures, the separating cylinder 2 includes a top plate 21, a side plate 22 of the square cylinder, and a side plate 23 of the bottom frustum of a square pyramid cylinder. A circular hole for the pellets to fall into is provided at the center of the top plate 21. The pellets fall from the central hole of the top plate 21 of the separating cylinder 2 and are discharged from the small bottom surface of the bottom frustum of a square pyramid cylinder 23. The bottom circumference of the upper connecting pipe 1 and the circumference of the central hole of the top plate 21 of the separating cylinder 2 are fully welded and connected, and the bottom surface of the upper connecting pipe 1 and the top plate 21 of the separating cylinder 2 are coplanar. The side length of the top plate 21 of the separating cylinder 2 is 1.5 - 2.0 times the inner diameter of the transport pipe. 1 - 4 equal-diameter exhaust holes are evenly opened on the top plate 21 of the separating cylinder 2 outside the bottom circumference of the upper connecting pipe 1, and the filling gas in the top cavity of the separating cylinder 2 is sucked by the induced draft fan. Attached Figure 2The diagonal dotted line is the circumferential partition board, and the square dotted line is the top edge of the lower connecting pipe 7. If the filling gas discharged by the induced draft fan contains a lot of dust, it will be purified by the dust collector and then emptied, otherwise it will be directly emptied. The exhaust holes of the separation cylinder 2 are not arranged on the side plate 22 of the separation cylinder 2, because this is likely to cause the pellets to slip into the exhaust pipe and block the suction failure of the induced draft fan. The bottom frustum cylinder 23 is the side plate of the frustum cylinder arranged upside down at 180°. The side length of the small bottom surface of the bottom frustum cylinder 23 is 0.25 to 0.75 times the inner diameter of the transport pipe.

[0016] As shown in the appendix Figure 3 As shown, a large number of equal-diameter air holes are vertically and evenly opened on the side plate of the bottom frustum cylinder 23, and the aperture of the air holes is 2 mm to 4 mm smaller than the diameter of the pellets. The side plate of the bottom frustum cylinder 23, the side plate of the outer frustum cylinder 3, the top ring plate of the gas collecting pipe 4, and the side plate of the inner frustum cylinder 5 enclose a pressure equalizing chamber. The large bottom edge of the bottom frustum cylinder 23 and the small bottom edge of the outer frustum cylinder 3 are fully welded and connected. The large bottom edge of the outer frustum cylinder 3 and the outer edge of the top ring plate of the gas collecting pipe 4 are fully welded and connected. The small bottom edge of the inner frustum cylinder 5 and the small bottom edge of the bottom frustum cylinder 23 are fully welded and connected. The large bottom edge of the inner frustum cylinder 5 and the inner edge of the top ring plate of the gas collecting pipe 4 are fully welded and connected. The outer edge of the top ring plate of the gas collecting pipe 4 is fully welded and connected to the large bottom edge of the outer frustum cylinder 3, and the inner edge of the top ring plate of the gas collecting pipe 4 is fully welded and connected to the large bottom edge of the inner frustum cylinder 5. A large number of equal-diameter air holes are evenly opened on the top ring plate of the gas collecting pipe 4, and the aperture of the air holes is 2 mm to 4 mm smaller than the diameter of the pellets. The small bottom edge of the middle frustum cylinder 6 is fully welded and connected to the side plate of the bottom frustum cylinder 23. The parallel side length distance between the two small bottom surfaces of the middle frustum cylinder 6 and the bottom frustum cylinder 23 is less than 50 mm. Air holes can be opened or not opened on the side plate of the bottom frustum cylinder 23 between the small bottom edge of the middle frustum cylinder 6 and the small bottom edge of the inner frustum cylinder 5. As shown in the appendix Figure 3There are no air holes opened on the side plates of the bottom frustum cylinder 23 between the small bottom edges of the middle frustum cylinder 6 and the small bottom edges of the inner frustum cylinder 5. The large bottom edge of the middle frustum cylinder 6 is fully welded to the top ring plate of the gas collector 4. The ring plate area between the large bottom edge of the outer frustum cylinder 3 and the large bottom edge of the middle frustum cylinder 6 is 50% of the area of the top ring plate of the gas collector 4. The large bottom surfaces of the outer frustum cylinder 3, the middle frustum cylinder 6, the inner frustum cylinder 5, and the top ring plate of the gas collector 4 are all horizontally arranged and coplanar. The small bottom surfaces of the outer frustum cylinder 3, the middle frustum cylinder 6, the inner frustum cylinder 5, the large bottom surface of the bottom frustum cylinder 23, and the small bottom surface of the bottom frustum cylinder 23 are all horizontally arranged. The side plates of the middle frustum cylinder 6 are between the side plates of the inner frustum cylinder 5 and the side plates of the outer frustum cylinder 3, dividing the uniform chamber into two equal parts. The top of the lower connecting pipe 7 is a square-to-round pipe, and the bottom is a round pipe. The inner diameter of the round pipe of the lower connecting pipe 7 is equal to the inner diameter of the upper connecting pipe 1. The top edge of the lower connecting pipe 7 is horizontally arranged and fully welded to the side plate of the inner frustum cylinder 5. The distance between the top surface of the lower connecting pipe 7 and the small bottom surface of the inner frustum cylinder 5 exceeds the inner diameter of the transport pipe. A large number of air holes are evenly opened on the opposite two isosceles trapezoidal plates of the side plates of the inner frustum cylinder 5 above the top surface of the lower connecting pipe 7, and the horizontal projections of the air holes do not overlap. No air holes are opened on the other two isosceles trapezoidal plates. After the clean gas passes through the air holes in the opposite two trapezoidal plates, a high-speed horizontal parallel flow is formed in the frustum space between the small bottom surface of the bottom frustum cylinder 23 and the top surface of the lower connecting pipe 7. Under the resistance of the downstream pipe pellet, the clean gas drives the remaining filling gas to flow back from the small bottom surface of the bottom frustum cylinder 23 to the central area of the separation cylinder 2.

[0017] As shown in the appendix Figure 1 As shown, the high-speed horizontal parallel flow of clean gas in the top cavity of the inner frustum cylinder 5 drives the remaining filling gas in the pellet gaps to flow back from the small bottom surface of the bottom frustum cylinder 23 to the inner cavity of the separation cylinder 2, flow upward through the central ball bed of the separation cylinder 2, and then be sucked into the induced draft fan. The bottom circumference of the lower connecting pipe 7 is flange-sealed to the top circumference of the downstream pipe. The top surface of the lower connecting pipe 7 is horizontally arranged and perpendicular to the central axis of the inner frustum cylinder 5. The inner diameters of the downstream pipe, the lower connecting pipe 7, the upper connecting pipe 1, and the upstream pipe are equal. The central axes of the upstream pipe, the upper connecting pipe 1, the separation cylinder 2, the outer frustum cylinder 3, the gas collector 4, the inner frustum cylinder 5, the middle frustum cylinder 6, the lower connecting pipe 7, and the downstream pipe are collinear, vertically installed, and pairwise sealed.

[0018] The principle of the invention for expelling the pellet filling gas is described as follows:

[0019] During the pellet transportation process, the pellet filling gas always moves downstream at the same speed. When the pellet moves to the top plate 21 of the separation cylinder 2, the pellet freely falls into the separation cylinder 2 under the action of its own gravity. During the falling process of the pellet, it follows the discrete body flow law, the interaction force between the pellets disappears, and the flow resistance of the pellet filling gas in the center of the upper connecting pipe 1 decreases. The suction effect of the induced draft fan makes the negative pressure in the near-wall area of the top cavity of the separation cylinder 2 as low as -20 Pa to -60 Pa. When the pellet filling gas flows to the top ring surface 21 of the separation cylinder 2 along with the pellet, since the side length of the separation cylinder 2 is 1.5 to 2 times the inner diameter of the transport pipe, the flow channel cross-sectional area suddenly expands, the flow velocity of the filling gas decreases, the filling gas and the pellet are quickly separated, and then under the strong suction effect of the induced draft fan, the streamline of the filling gas rapidly reverses 180° and flows to the top exhaust port of the separation cylinder 2, achieving the effect of expelling most of the filling gas. Under the action of the plane flow formed by the clean gas passing through the air holes on the side plate of the bottom frustum cylinder 23, on the one hand, the pellet filling gas in the near-wall area of the separation cylinder 2 leaves the pellet bed and flows towards the top exhaust port of the separation cylinder 2, and on the other hand, under the guiding action of the pellets in the near-wall area of the separation cylinder 2 sliding along the side plate of the bottom frustum cylinder 23 towards the small bottom surface of the bottom frustum cylinder 23, the pellet filling gas in the near-wall area of the separation cylinder 2 flows towards the small bottom surface of the bottom frustum cylinder 23. Under the combined guiding action of the plane flow in the near-wall area of the separation cylinder 2 and the downward volleyball of the small bottom surface of the bottom frustum cylinder 23 on the pellet filling gas flow in the pellet bed of the separation cylinder 2, the pellet filling gas in the pellet bed of the separation cylinder 2 converges towards the center, that is, there is less filling gas near the wall and more filling gas in the center, providing a basis for organizing an efficient washing area (the top cavity area of the inner frustum cylinder 5 above the top surface of the lower connecting pipe 7) downstream of the separation cylinder 2.

[0020] The pellets pass through the large bottom surface of the bottom quadrangular frustum cylinder 23 into the inner cavity of the bottom quadrangular frustum cylinder 23, then fall from the small bottom surface of the bottom quadrangular frustum cylinder 23, and then enter the top cavity area (high-efficiency pellet washing area) of the inner quadrangular frustum cylinder 5. After being washed by numerous small air streams on the left and right through stagnation impact and horizontal shear washing, they fall into the lower connecting pipe 7. The side plates of the bottom quadrangular frustum cylinder 23 separate the inner cavity of the separation cylinder 2 from the pressure equalizing chamber, and maintain the negative pressure in the inner cavity of the separation cylinder 2 and the positive pressure in the pressure equalizing chamber, so as to maintain the upward flow of the pellet bed filling gas and the clean gas in the pressure equalizing chamber to the exhaust port at the top of the separation cylinder 2. The side plates of the middle quadrangular frustum cylinder 6 divide the pressure equalizing chamber into two inner and outer pressure equalizing chambers. Since 50% of the ventilation area outside the top ring plate of the gas collecting pipe 4 (50% of the ventilation area of the top ring plate of the gas collecting pipe 4) faces the pressure equalizing chamber, and 50% of the ventilation area inside the top ring plate of the gas collecting pipe 4 (50% of the ventilation area of the top ring plate of the gas collecting pipe 4) faces the inner pressure equalizing chamber, 50% of the clean gas blown into the inner cavity of the gas collecting pipe 4 enters the near-wall area of the separation cylinder 2 through the air holes on the side plates of the bottom quadrangular frustum cylinder 23 from the outer pressure equalizing chamber, and the remaining 50% of the clean gas is horizontally sprayed into the top cavity of the inner quadrangular frustum cylinder 5 through the air holes on the two opposite trapezoidal plates of the side plates of the inner quadrangular frustum cylinder 5 to form a high-speed horizontal parallel flow. Under the action of the pressure difference (positive pressure in the outer pressure equalizing chamber - negative pressure in the separation cylinder 2), the clean gas in the outer pressure equalizing chamber passes through the air holes on the side plates of the bottom quadrangular frustum cylinder 23 and then through the gaps in the pellet bed in the near-wall area of the separation cylinder 2 and flows upward from bottom to top, preventing the pellet bed filling gas in the near-wall area of the separation cylinder 2 from flowing downward from top to bottom. The clean gas in the inner pressure equalizing chamber is horizontally sprayed into the top cavity of the inner quadrangular frustum cylinder 5 through the air holes on the two opposite trapezoidal plates of the side plates of the inner quadrangular frustum cylinder 5, and forms a high-speed horizontal parallel flow in the top cavity area of the inner quadrangular frustum cylinder 5. During the process of the pellets passing through the top cavity of the inner quadrangular frustum cylinder 5, each pellet is washed by the clean gas. Under the action of the negative pressure suction at the top cavity of the separation cylinder 2 and the resistance of the pellet bed in the lower connecting pipe 7, the clean gas together with the remaining filling gas of the pellets flows upward from bottom to top through the small bottom surface of the bottom quadrangular frustum cylinder 23, and at the same time prevents the remaining filling gas in the pellet bed in the central area of the separation cylinder 2 from flowing downward from top to bottom, and finally completely expels the remaining filling gas in the pellet gaps, so as to ensure that when the pellets fall into the lower connecting pipe 7, only the clean gas surrounds the pellets, and each pellet is completely washed. The pellets in the separation cylinder 2 are discretely passed through the high-efficiency washing area, and the remaining filling gas hiding in the pellet gaps is prevented from continuing to flow into the lower connecting pipe 7. At the same time, the negative pressure in the top cavity of the separation cylinder 2 also reduces the amount of gap filling gas flowing downward with the pellets from top to bottom.

[0021] The invention requires the configuration of induced draft fans to ensure that the negative pressure in the top cavity of the separation cylinder 2 reaches -20 Pa to -60 Pa. To increase the suction force of the induced draft fans on the filling gas in the top cavity of the separation cylinder 2, the top cavity of the separation cylinder 2 can be evenly divided, equal-diameter exhaust holes are opened on the top surface of each divided area, and one induced draft fan is arranged for each exhaust hole. All the induced draft fans have the same model and motor power, so as to avoid the irregular flow of the pellet filling gas in the top cavity of the separation cylinder 2 and affect the quick discharge and expulsion effect of the filling gas. The invention requires the configuration of Roots blowers to ensure that the clean gas can pass through the air holes on the side plates of the bottom quadrangular prism cylinder 23 and form a planar flow in the near-wall area of the separation cylinder 2, and can pass through the air holes on the two opposite trapezoidal plates at the top of the side plates of the inner quadrangular prism cylinder 5 and form a horizontal parallel flow in the top cavity of the inner quadrangular prism cylinder 5. The air supply mode of the gas collecting pipe 4 can be designed as a multi-chamber air supply (attached Figure 4 as a single-chamber air supply) mode to improve the pressure equalization effect of the pressure equalization chamber and avoid the non-uniformity of the planar flow in the near-wall area of the separation cylinder 2. The gas collecting pipe 4 is evenly divided (attached Figure 4 not marked), equal-diameter air supply holes are opened in each divided area, and one Roots blower is connected to each air supply hole. All the Roots blowers have the same model and motor power.

[0022] When using the present invention, it is required to connect two deoxidizing devices in series and of the same type to respectively complete the two-step operation of driving out the filling oxygen (target gas) with N2 (clean gas) and driving out the filling nitrogen (target gas) with H2 (clean gas), so as to realize the safe replacement of the pellet filling oxygen with H2, and there is no possibility of direct contact between oxygen and hydrogen molecules, thus ensuring the stable and safe performance of hydrogen reduction smelting. The one-step method of driving out the filling oxygen, that is, only using one deoxidizing device to directly drive the pellet filling oxygen with H2. Due to the small gaps between pellets and the large flow resistance of pellets, the flow heat transfer and mass transfer conditions of hydrogen and oxygen molecules are poor, and the local retention of hydrogen molecules is likely to cause the hydrogen concentration to be within the flammable range, that is, the hidden danger of deflagration has not been completely eliminated.

[0023] When the present invention is used, the top surface of the connecting pipe 1 on the first deoxidation device is flange-sealedly connected to the bottom surface flange of the upstream pipe, the bottom surface of the lower connecting pipe 7 is flange-sealedly connected to the top surface flange of the connecting pipe 1 on the second deoxidation device, and the bottom surface of the lower connecting pipe 7 of the second deoxidation device is flange-sealedly connected to the top surface flange of the downstream pipe. Nitrogen (clean gas) at 0.4 MPa to 0.6 MPa is introduced into the gas collecting pipe 4 of the first deoxidation device. The oxygen in the pellet filling (target gas) and nitrogen are discharged from the exhaust holes at the top of the separation cylinder 2, and the negative pressure in the cavity at the top of the separation cylinder 2 reaches -20 Pa to -60 Pa. Control the downward movement speed of the pellets in the upper connecting pipe 1, the separation cylinder 2 and the lower connecting pipe 7, so that the cavity with a height of 1 to 2 times the inner diameter of the transport pipe below the top plate 21 of the separation cylinder 2 is not filled with pellets, the height of the pellet bed in the separation cylinder 2 does not exceed the inner diameter of the transport pipe, and the cavity at the top of the inner quadrangular frustum cylinder 5 above the top surface of the lower connecting pipe 7 is not filled with pellets. The height of the cavity at the top of the inner quadrangular frustum cylinder 5 is equal to 1 to 2 times the inner diameter of the transport pipe. Hydrogen (clean gas) at 0.4 MPa to 0.6 MPa is introduced into the gas collecting pipe 4 of the second deoxidation device. The nitrogen in the pellet filling (target gas) and hydrogen are discharged from the exhaust holes at the top of the separation cylinder 2, and the negative pressure in the cavity at the top of the separation cylinder 2 reaches -20 Pa to -60 Pa. Control the downward movement speed of the pellets in the upper connecting pipe 1, the separation cylinder 2 and the lower connecting pipe 7, so that the cavity with a height of 1 to 2 times the inner diameter of the transport pipe below the top plate 21 of the separation cylinder 2 is not filled with pellets, the height of the pellet bed in the separation cylinder 2 does not exceed the inner diameter of the transport pipe, and the cavity at the top of the inner quadrangular frustum cylinder 5 below the small bottom surface of the bottom quadrangular frustum cylinder 23 is not filled with pellets. The height of the cavity at the top of the inner quadrangular frustum cylinder 5 is equal to 1 to 2 times the inner diameter of the transport pipe.

[0024] When the height of the pellet bed in the separation cylinder 2 exceeds the inner diameter of the transport pipe, the flow of the remaining filling gas and the clean gas through the pellet bed will be significantly hindered due to the excessive accumulation of pellets. The pellets in the upper connecting pipe 1 continuously impact the top surface of the pellet bed, controlling the height of the pellet bed in the separation cylinder 2. The bottom quadrangular frustum cylinder 23 is arranged in a "V" shape, and together with the horizontal parallel flow of the cavity at the top of the inner quadrangular frustum cylinder 5 flowing upward from bottom to top, it is beneficial to break the material arch in the inner cavity of the separation cylinder 2 and increase the stability of pellet transport in the invention device. In addition, the "V" shape arrangement of the bottom quadrangular frustum cylinder 23 is beneficial for the pellets in the near-wall area of the separation cylinder 2 to move towards the discharge port, achieving the effect of discharging all the pellets in the separation cylinder 2.

[0025] The use of the invention requires correctly configuring the rated air volume of each fan and controlling the moving speed of the pellets to ensure the stability of the operation of pellet transport to expel the filling gas. The total air volume of the induced draft fan exceeds the sum of the total air volume of the Roots blower and the pellet filling gas volume. The moving speed of the pellets in the upper connecting pipe 1 is equal to the moving speed of the pellets in the lower connecting pipe 7, and the discharging speed of the pellets in the bottom quadrangular frustum cylinder 23 is equal to the moving speed of the pellets in the upper connecting pipe 1, maintaining the height of the pellet bed in the separation cylinder 2 equal to the inner diameter of the transport pipe and the stability of the cavity areas upstream and downstream of the pellet bed.

[0026] The structural features, technical features and the resulting technical effects of the invention are described in detail as follows:

[0027] The device of the present invention has the structural features of "pellets fall from the central hole of the top plate 21 of the separation cylinder 2, the top side length of the separation cylinder 2 is 1.5 to 2 times the inner diameter of the transport pipe, the top surface of the pellet bed in the separation cylinder 2 is 1 to 2 times the inner diameter of the transport pipe away from the inner wall of the top of the separation cylinder 2, the negative pressure in the top cavity of the separation cylinder 2 reaches -20 Pa to -60 Pa, and the exhaust holes are evenly arranged on the top plate 21 of the separation cylinder 2". The technical effects caused by this structural feature are "efficient separation of the main filling gas and pellets, the induced draft fan sucks the main filling gas in the top cavity of the separation cylinder 2, and enriches the solution to the problem of the diffusion and flow of the filling oxygen in the central pellets to the near-wall area. When the pellets in the upper connecting pipe 1 enter the separation cylinder 2, due to the sudden expansion of the flow channel area of the filling gas and the deceleration of the filling gas, the negative pressure of -20 Pa to -60 Pa in the near-wall area of the top cavity of the separation cylinder 2 improves the ability of the filling gas streamline to reverse rapidly. Coupled with the fact that the pellets become discrete bodies and the interaction force between the pellets disappears, the resistance for the filling gas to move out from the gaps between the pellets becomes smaller. When the pellets pass through the top cavity of the separation cylinder 2, most of the process of the filling gas detaching and expelling from the gaps between the pellets is completed, naturally reducing the difficulty and input of driving the remaining filling gas with clean gas.

[0028] The device of the present invention has the structural features of "the bottom frustum cylinder 23 is arranged upside down by 180°, and the small bottom side of the bottom frustum cylinder 23 is 0.25 to 0.75 times the inner diameter of the transport pipe. The side plates of the bottom frustum cylinder 23, the side plates of the outer frustum cylinder 3, the top ring plate of the gas collecting pipe 4 and the side plates of the inner frustum cylinder 5 enclose a pressure equalizing chamber, and the pressure equalizing chamber is divided into an inner and an outer pressure equalizing chamber by the side plate of the middle frustum cylinder 6. 50% of the clean gas passes through the outer pressure equalizing chamber and the air holes on the side plate of the bottom frustum cylinder 23 to form a planar flow flowing through the pellet gaps in the near-wall area of the separation cylinder 2, and 50% of the clean gas passes through the inner pressure equalizing chamber and the air holes at the top of the side plate of the inner frustum cylinder 5 and is sprayed into the top cavity of the inner frustum cylinder 5 to form a horizontal parallel flow. When the pellets in the separation cylinder 2 pass through the horizontal parallel flow area in a discrete state, the filling gas flows back to the separation cylinder 2 along with the clean gas". The technical effects caused by this structural feature are "the planar flow drives the remaining filling gas in the near-wall area of the separation cylinder 2, and the horizontal parallel flow drives the remaining filling gas in the central area of the separation cylinder 2, enriches the solution to the expulsion of the filling oxygen in the pellet gaps, and ensures the economy and effect of the expulsion of the remaining filling oxygen in the pellets".

[0029] The device of the present invention has a structural feature of "front balloon separation zone - separation cylinder 2 ball bed - rear balloon separation zone". The technical effect caused by this structural feature is that "the main part and the remaining part of the pellet filling gas are expelled twice. The front balloon separation zone completes the expulsion of the main filling gas, saving the consumption of clean gas required for the subsequent expulsion of the remaining filling gas. The rear balloon separation zone completes the expulsion of the remaining filling gas, which not only improves the operation economy of the device but also ensures the expulsion effect of the pellet filling gas". The top cavity of the separation cylinder 2 with a height of 1 to 2 times the inner diameter of the transport pipe below the top plate 21 of the separation cylinder 2 is the front balloon separation zone. The upstream pipe pellets in the front balloon separation zone pass through the inner cavity of the top of the separation cylinder 2 in a discrete state, completing the separation process of the pellets and the filling gas. Most of the filling gas flows out and is expelled through the suction of the induced draft fan from the gaps between the pellets. The top cavity of the inner frustum cylinder 5 with a height equal to the inner diameter of the transport pipe below the small bottom surface of the bottom frustum cylinder 23 is the rear balloon separation zone. A high-speed horizontal parallel flow of clean gas is formed in the rear balloon separation zone, and the pellets discharged from the small bottom surface of the bottom frustum cylinder 23 are washed one by one when passing through the horizontal parallel flow in a discrete state. The filling gas near the surface of each pellet is expelled through the impact and shear flow of the clean gas, completing the operation of expelling the remaining filling gas from the pellets. The air supply pressure of the Roots blower exceeds the resistance of the central ball bed of the separation cylinder 2 and is much less than the resistance of the lower connecting pipe 7 and the downstream pipe pellets. The top cavity of the inner frustum cylinder 5 above the top surface of the lower connecting pipe 7 is under positive pressure, and the horizontal parallel flow of clean gas in the top cavity of the inner frustum cylinder 5 can only be discharged from the small bottom surface of the separation cylinder 2 and cannot be discharged from the lower connecting pipe 7. To maintain the mass conservation of the clean gas in the top cavity of the inner frustum cylinder 5, the flow rate of the clean gas entering the top cavity of the inner frustum cylinder 5 is equal to the flow rate of the clean gas leaving the small bottom surface of the bottom frustum cylinder 23. The clean gas blown into the separation cylinder 2 through the small bottom surface of the bottom frustum cylinder 23 is sufficient to drive the filling gas in the central ball bed of the separation cylinder 2. The invention can solve the problem of large resistance when the filling gas in the center of the ball bed flows to the edge area and the problem of filling oxygen in the backflow area on the leeward side of the pellets.

[0030] The method of using the inventive device has the technical feature of "two-step removal of filled oxygen by driving out filled oxygen (target gas) with N2 (clean gas) and driving out filled nitrogen (target gas) with H2 (clean gas)". The inventive device serially uses two pellet transport deoxidizers. First, the first deoxidizer completes driving out filled oxygen (target gas) with N2 (clean gas), and then the second deoxidizer completes driving out filled nitrogen (target gas) with H2 (clean gas), achieving safe replacement of the filled oxygen in the pellets by H2 without direct contact between oxygen and hydrogen molecules. Although it increases the investment in one more deoxidizer and the consumption of clean gas N2, the subsequent hydrogen reduction smelting has guaranteed stability and safety, enriching the solutions to the problems of H2 deflagration and difficult safe transportation. To strengthen the effect of driving out filled oxygen (target gas) with N2 (clean gas) and driving out filled nitrogen (target gas) with H2 (clean gas), two or more deoxidizers (with N2 as the clean gas and filled oxygen as the target gas) can be used in series and two or more deoxidizers (with H2 as the clean gas and N2 as the target gas) can be used in series. The upstream pipe is connected to the connecting pipe on the first deoxidizer (with N2 as the clean gas), and then the lower connecting pipe of the previous deoxidizer (with N2 as the clean gas) is connected to the upper connecting pipe of the next deoxidizer (with N2 as the clean gas). The lower connecting pipe of the last deoxidizer (with N2 as the clean gas) is connected to the upper connecting pipe of the first deoxidizer (with H2 as the clean gas), and then the lower connecting pipe of the previous deoxidizer (with H2 as the clean gas) is connected to the upper connecting pipe of the next deoxidizer (with H2 as the clean gas). The lower connecting pipe of the last deoxidizer (with H2 as the clean gas) is connected to the downstream pipe. The larger the diameter of the transport pipe, the more deoxidizers are configured for each step in the two-step method. The invention avoids using the design of removing filled oxygen in one step. Removing the filled oxygen in the pellets in one step, that is, only using one deoxidizer to directly drive out the filled oxygen in the pellets with hydrogen, there are countless opportunities for direct contact and mixing between hydrogen and oxygen molecules. Due to the small gap size of the pellets and the large flow resistance of the pellets, the flow, heat transfer, and mass transfer conditions of hydrogen and oxygen molecules are poor, and local retention of hydrogen molecules is likely to cause the hydrogen concentration to be within the flammable range, that is, the hidden danger of deflagration has not been completely eliminated.

[0031] The invention has the technical feature of "continuously removing the oxygen filled in pellets". In the first deoxygenation device, the pellets continuously fall into the separation cylinder 2 through the connecting pipe 1. The pellets in the separation cylinder 2 continuously fall into the lower connecting pipe 7 from the small bottom surface of the bottom quadrangular frustum cylinder 23, then flow through the connecting pipe 1 of the second deoxygenation device and continuously fall into the separation cylinder 2. The pellets in the separation cylinder 2 continuously fall into the lower connecting pipe 7 from the small bottom surface of the bottom quadrangular frustum cylinder 23. Finally, each pellet is surrounded by hydrogen and falls into the subsequent equipment. During the whole process, the gas flow in the separation cylinder 2 of the two deoxygenation devices and the pellet transportation are stable, without retention and blockage. Each link of each device always satisfies the law of mass conservation of the pellets, and it is suitable for large-capacity hydrogen reduction smelting. When the invention is used, both the upstream pipe and the downstream pipe are vertical pipes, filling the entire cross-sectional area of the pellet filling and transportation pipe. To remove the oxygen filled in the pellets, the conventional chemical method is designed as "packing the pellets in separate tanks + evacuating the airtight and isolated ball tanks at the inlet under the premise of vacuum" or "packing the pellets in separate tanks + using N2 to drive away the oxygen filled in the pellets". This method has reliable safety performance, but it has poor economy, great difficulty in vacuum pumping, discontinuous deoxygenation operation, low production efficiency, and there is still the problem that the filling gas in the center of the ball bed is difficult to diffuse to the near wall, so it is not suitable for large-capacity hydrogen reduction smelting production.

[0032] The sintered pellet safety transportation and smelting device for hydrogen reduction smelting iron in iron and steel enterprises can use the present invention.

[0033] The invention has good economy, can efficiently transport sintered pellets and ensure the safe and stable operation of the sintered pellet transportation and smelting device. The static pressure distribution of the pellet transportation pipe equipment is stable, without fluctuating changes, without micro-explosion or explosion, the effect of removing the filled oxygen is stable, and it does not carry the filled oxygen into the smelting furnace.

Claims

1. Oxygen removing device for filling the gaps between pellets, mainly including an upper connecting pipe, a square cylinder-shaped separation cylinder, an outer frustum of a square pyramid cylinder, a square ring-shaped gas collecting pipe, an inner frustum of a square pyramid cylinder, a middle frustum of a square pyramid cylinder, a bottom frustum of a square pyramid cylinder and a lower connecting pipe. After the transport pipe is disconnected into upper and lower pipes, the flange of the lower pipe is connected to the lower connecting pipe, and the flange of the upper pipe is connected to the upper connecting pipe. Its main features are as follows: The separation cylinder includes a square top plate, square cylinder side plates and bottom frustum of a square pyramid cylinder side plates. A circular hole is provided at the center of the separation cylinder top plate, and the circumference of the hole is fully welded to the bottom circumference of the upper connecting pipe. The side length of the separation cylinder top plate is 1.5 - 2 times the inner diameter of the transport pipe. 1 - 4 equal-diameter exhaust holes are evenly opened on the separation cylinder top plate outside the bottom circumference of the upper connecting pipe. The bottom frustum of a square pyramid cylinder is arranged upside down by 180°. The small bottom side of the bottom frustum of a square pyramid cylinder is 0.25 - 0.75 times the inner diameter of the transport pipe. A large number of equal-diameter air holes are vertically opened on the side plates of the bottom frustum of a square pyramid cylinder. The side plates of the bottom frustum of a square pyramid cylinder, the side plates of the outer frustum of a square pyramid cylinder, the top ring plate of the gas collecting pipe and the side plates of the inner frustum of a square pyramid cylinder enclose a pressure equalizing chamber. The large bottom side of the bottom frustum of a square pyramid cylinder is fully welded to the small bottom side of the outer frustum of a square pyramid cylinder. The large bottom side of the outer frustum of a square pyramid cylinder is fully welded to the outer edge of the top ring plate of the gas collecting pipe. The small bottom side of the inner frustum of a square pyramid cylinder is fully welded to the small bottom side of the bottom frustum of a square pyramid cylinder. The large bottom side of the inner frustum of a square pyramid cylinder is fully welded to the inner edge of the top ring plate of the gas collecting pipe. A large number of equal-diameter air holes are evenly opened on the top ring plate of the gas collecting pipe. The small bottom side of the middle frustum of a square pyramid cylinder is fully welded to the side plates of the bottom frustum of a square pyramid cylinder. The distance between the parallel sides of the small bottom surface of the middle frustum of a square pyramid cylinder and the small bottom surface of the bottom frustum of a square pyramid cylinder is less than 50 mm. The annular plate area between the large bottom side of the outer frustum of a square pyramid cylinder and the large bottom side of the middle frustum of a square pyramid cylinder is 50% of the area of the top ring plate of the gas collecting pipe. The lower connecting pipe is a square-to-round pipe, and the inner diameter of the round pipe is equal to the inner diameter of the upper connecting pipe. The top surface of the lower connecting pipe is horizontally arranged and the four sides are fully welded to the side plates of the inner frustum of a square pyramid cylinder. Above the top surface of the lower connecting pipe, a large number of air holes are evenly opened on the two opposite trapezoidal plates of the side plates of the inner frustum of a square pyramid cylinder, and the horizontal projections of the air holes do not overlap. 50% of the clean gas blown into the gas collecting pipe forms a plane flow through the air holes on the side plates of the bottom frustum of a square pyramid cylinder and enters the near-wall area of the separation cylinder, driving the remaining filling gas of the near-wall pellets to leave the ball bed and flow towards the exhaust holes of the separation cylinder. The remaining 50% of the clean gas forms a horizontal parallel flow in the top cavity of the inner frustum of a square pyramid cylinder after passing through the air holes on the two trapezoidal plates, and the parallel flow drives the remaining filling gas to flow back into the separation cylinder from the small bottom surface of the bottom frustum of a square pyramid cylinder.

2. The usage method of the oxygen removing device for filling the gaps between pellets as described in claim 1, its main features are as follows: Two-stage deoxygenation devices are used in series. The flange of the upper connecting pipe of the first-stage deoxygenation device is connected to the upstream pipe, the flange of the lower connecting pipe is connected to the upper connecting pipe of the second-stage deoxygenation device, and the flange of the lower connecting pipe is connected to the downstream pipe. Nitrogen and hydrogen are respectively introduced into the gas collecting pipes of the first and second-stage deoxygenation devices. The negative pressure in the top cavity of the separation cylinder of each deoxygenation device is -20 Pa to -60 Pa, the height of the top cavity is equal to 1 - 2 times the inner diameter of the transport pipe, the height of the ball bed does not exceed the inner diameter of the transport pipe, the height of the top cavity of the inner frustum of a square pyramid cylinder is equal to 1 - 2 times the inner diameter of the transport pipe, and the static pressure of the gas collecting pipe is maintained at 0.4 MPa to 0.6 MPa.

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