Flow distribution device of flue gas distributor of air pre-heater of delayed coking device

Abstract

The invention provides a flow distribution device of a flue gas distributor of an air pre-heater of a delayed coking device. The flow distribution device comprises an upper guide wheel and a lower guide wheel. The upper guide wheel is composed of an outer barrel and a plurality of deflection guide vanes which are evenly distributed. The edges, making contact with the inner wall of the outer barrel, of the deflection guide vanes deflect by a specific angle in the circumferential direction from an inlet to an outlet. The lower guide wheel is composed of an outer cylinder and a plurality of straight guide vanes evenly distributed, and the outer edges of the straight guide vanes are tightly attached to the inner wall of the outer cylinder. The upper guide wheel and the lower guide wheel of the flow distribution device can be installed separately or integrally according to actual on-site conditions. The sizes of the flow distribution devices are different according to different installation modes. The deflection guide vane and the straight guide vane in the guide wheel interact with each other, so that the flue gas bias flow phenomenon in the flue gas distributor is effectively improved, and equal-flow distribution of flue gas in the distributor is realized.

Description

Technical Field

[0001] This invention relates to the field of gas distribution technology, and to a flow distribution device for distributing flue gas in the air preheater of a delayed coking unit. Background Technology

[0002] The air preheater (hereinafter referred to as air preheater) of the waste heat recovery system of the delayed coking unit consists of two plate heat exchangers operating in parallel. The high-temperature flue gas from the combustion furnace enters the flue gas distributor through the flue gas pipeline. In the distributor, it is divided into two streams, which enter the heat exchangers on both sides to exchange heat with the cold air. After the heat exchange is completed, the streams merge at the outlet of the heat exchangers and are discharged.

[0003] Due to space constraints at the installation site, the air preheater and its flue gas distributor are mismatched with the inlet piping system, resulting in significant flue gas flow deviation within the distributor. The flue gas flow rate allocated to one heat exchanger is greater than that to the other, leading to a temperature difference in the cold flue gas at the outlets of the two heat exchangers. This causes the heat exchangers to operate under non-design conditions, impacting their safety and reliability. Therefore, it is necessary to address the flue gas flow deviation problem within the distributor, ensuring that the heat loads of the two heat exchangers below the distributor are comparable, thereby improving the overall heat exchange efficiency of the unit. Summary of the Invention

[0004] This invention provides a flow distribution device that can effectively solve the problems of flue gas flow deviation and uneven flow in the flue gas distributor of the air preheater in delayed coking units. This device can achieve equal flow distribution of flue gas on the left and right branches of the flue gas distributor and control the velocity distribution of the flow cross section without changing the structure and layout of the on-site equipment, thereby improving the heat exchange efficiency of the air preheater.

[0005] This invention provides the following technical solutions:

[0006] A flow distribution device for a flue gas distributor in an air preheater of a delayed coking unit includes an upper guide wheel and a lower guide wheel. The upper guide wheel consists of two sets of four deflecting guide vanes and an outer cylinder. The inner edge of the deflecting guide vanes coincides with the axis of the outer cylinder, and the outer edge of the deflecting guide vanes in contact with the outer cylinder rotates circumferentially through a specific angle from the inlet to the outlet. The lower guide wheel consists of two sets of four straight guide vanes and an outer cylinder. The inner edge of the four straight guide vanes coincides with the axis of the outer cylinder, and the outer edge is in close contact with the inner wall of the outer cylinder.

[0007] The distribution device can be installed in the distributor piping system in two ways: split type and integral type. The installation method determines the deflection angle of the upper guide wheel deflector vane, and the air preheater and its piping system layout determine the deflection direction and installation orientation of the upper guide wheel deflector vane.

[0008] When installed in a split configuration, the upper guide wheel is located slightly behind the inlet of the vertical flue gas pipe. One set of deflecting guide vanes on the upper guide wheel must have its leading edge aligned with the axis of the horizontal flue gas pipe, while the other set of deflecting guide vanes is circumferentially evenly distributed with the first set. The lower guide wheel is installed at the outlet of the vertical flue gas pipe, and its outlet is the inlet of the flue gas distributor. The trailing edge of one set of straight guide vanes on the lower guide wheel must be aligned with the left and right symmetrical planes of the flue gas distributor, while the other set of guide vanes on the lower guide wheel is circumferentially evenly distributed with the first set.

[0009] In the integrated installation, the number of deflecting guide vanes on the upper guide wheel is the same as the number of straight guide vanes on the lower guide wheel. The trailing edge of the deflecting guide vane connects with the leading edge of the straight guide vane on the lower guide wheel, forming a combined guide vane that shares a single outer cylinder, thus becoming a composite guide wheel. The composite guide wheel is installed between the inlet of the flue gas distributor and the outlet of the vertical flue gas pipe, with the outlet of the composite guide wheel being the inlet of the flue gas distributor. The deflection angle of the deflecting guide vane in the combined guide wheel is greater than that in the separate installation, requiring that the leading edge line of one set of combined guide vanes be parallel to the axis of the horizontal flue gas inlet pipe.

[0010] Optionally, the guide wheel may consist of only a few guide vanes, which are directly fixed at specific positions on the vertical flue gas pipeline without an outer cylinder, thus simplifying the manufacturing and installation process.

[0011] Optionally, when the distribution device is installed in a split configuration, the number of guide vanes on the upper and lower guide wheels may be different; when it is installed as a single unit, the number of guide vanes on the upper and lower guide wheels may be the same.

[0012] Optionally, to reduce flow losses, the leading edge of the guide vane is machined into an arc shape, and the trailing edge is thinned.

[0013] This invention, through the design and installation of an upper guide wheel with deflecting guide vanes and a lower guide wheel with straight guide vanes, achieves equal flow distribution of flue gas in the left and right branches of the distributor outlet. The device of this invention has a simple structure, is easy to manufacture and install, has a small flow pressure drop, and can effectively improve the heat exchange efficiency and safety reliability of the air preheater. Attached Figure Description

[0014] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0015] Figure 1 This is a schematic diagram of the flow distribution device of the present invention being installed separately in the vertical air inlet pipe of the distributor;

[0016] Figure 2 This is a schematic diagram of the upper and lower guide wheels of the flow distribution device in a split installation according to an embodiment of the present invention;

[0017] Figure 3This is a schematic diagram of the structure of the upper guide wheel deflection guide vane and the lower guide wheel straight guide vane during the split installation of an embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of the overall installation of the flow distribution device at the inlet of the flue gas distributor in an embodiment of the present invention;

[0019] Figure 5 This is a schematic diagram of the composite guide wheel according to an embodiment of the present invention;

[0020] Figure 6 This is a schematic diagram of the combined guide vane structure of the flow distribution device according to an embodiment of the present invention.

[0021] In the figure: 1. Horizontal flue gas pipe; 2. 90° bend; 3. Vertically descending flue gas pipe; 4. Flue gas distributor; 5. Parallel heat exchanger; 6. Lower guide wheel of split-type distribution device; 7. Upper guide wheel of split-type distribution device; 61. Straight guide vane of lower guide wheel of split-type distribution device; 62. Outer shell of lower guide wheel of split-type distribution device; 71. Deflecting guide vane of upper guide wheel of split-type distribution device; 72. Outer shell of upper guide wheel of split-type distribution device; 63. Straight guide vane part of combined guide vane of integral distribution device; 73. Deflecting guide vane part of combined guide vane of integral distribution device; 64(74) Outer shell of integral distribution device. Detailed Implementation

[0022] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the exemplary embodiments shown in the drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Different optional technical solutions in the embodiments described below can be combined to form new embodiments.

[0023] Figure 1The diagram shows the air preheater and its flue gas piping system. The top of the air preheater 5 is the flue gas distributor 4. Flue gas enters the flue gas distributor 4 through the horizontal flue gas pipe 1, the 90° bend 2, and the vertical downcomer 3. After being diverted, it enters the lower part of the air preheater 5. The angle between the axis of the horizontal flue gas pipe 1 and the left and right symmetrical planes of the flue gas distributor 4 is less than 90°. When using a split-type installation, the upper guide wheel 7 of the distribution device is installed slightly below the inlet of the vertical flue gas pipe, requiring that the leading edge of one set of deflecting guide vanes is along the axis of the horizontal flue gas pipe 1. The two sets of deflecting guide vanes 71 in the upper guide wheel 7 are evenly distributed circumferentially, with the outer edges of the guide vanes tightly against the inner wall of the outer casing 72. The lower guide wheel 6 consists of two sets of straight guide vanes 61 and an outer casing 62, with the outer edges of the straight guide vanes tightly against the inner wall of the outer casing 62. The lower guide wheel 6 is located at the inlet of the flue gas distributor 4. One set of straight guide vanes has its leading edge coinciding with the left and right symmetrical planes of the flue gas distributor 4, while the other set of straight guide vanes is circumferentially evenly distributed with the first set. The flue gas entering the vertical downcomer 3 through the 90° bend 2 is deflected by the deflecting guide vanes of the upper guide wheel. When the flue gas enters the lower guide wheel 6, most of its rotational momentum is eliminated by the straight guide vanes 61, causing it to enter the flue gas distributor 4 below the lower guide wheel 6 in an axial, approximately symmetrical manner. After being evenly distributed by the flue gas distributor, the gas enters the heat exchangers on both sides, achieving equal load operation of the heat exchangers on both sides.

[0024] Figure 4 This is a schematic diagram of the air preheater device structure when the distribution device is installed as a whole. The trailing edge of the deflecting guide vane 73 of the upper guide wheel connects with the leading edge of the straight guide vane 63 of the lower guide wheel to form a combined guide vane, which shares a single outer shell 74 (or 64) to form a composite guide wheel, which is installed as a whole at the inlet position of the flue gas distributor 4. It is required that the leading edge line of the set of deflecting guide vanes 73 of the combined guide vane is parallel to the axis of the horizontal flue gas pipe 1. The deflecting guide vane 73 forces the flue gas to deflect, while the straight guide vane 63 eliminates most of the rotational motion of the flue gas. The combined guide vanes work together to adjust the distribution of flue gas velocity on the flow cross section, so that the flue gas, after entering the distributor, can be divided into two equal-flow-rate airflows on the left and right sides, which then enter the heat exchangers on both sides.

[0025] Working Principle: In the delayed coking unit, the flow in the air preheater flue gas inlet pipeline (horizontal flue gas pipe 1, 90° bend 2, and vertical downcomer 3) is symmetrically distributed relative to the horizontal inlet pipe axis, while the flow in the downstream distributor 4 and air preheater 5 is left-right symmetrical, resulting in a mismatch between the two flows. When the deflecting guide vanes 71 (or 73) of the upper guide wheel 7 of this invention force the flue gas to deflect and flow to the inlet of the lower guide 6, the flow of the flue gas in the flue gas pipe rotates to approximately symmetrical about the left-right symmetry plane of the flue gas distributor. The straight guide vanes 61 (or 63) of the lower guide wheel 6 guide the airflow from spiral flow to simple axial flow, approximately symmetrically distributed into the flue gas distributor, where it is divided into two equal-flow-rate airflows entering the lower heat exchanger, achieving equal-load operation of the two heat exchangers.

[0026] It should be noted that the above description is merely a preferred embodiment of the present invention and should not be used to limit the scope of protection of the present invention. Although the above embodiments provide a detailed description of the present invention, various modifications and variations made by those skilled in the art based on the present invention are all within the scope of protection claimed by the present invention.

Claims

1. A distribution device for a flue gas distributor, characterized in that, The flow distribution device includes an upper guide wheel and a lower guide wheel. The upper guide wheel is composed of evenly distributed deflecting guide vanes and an outer shell, and the lower guide wheel is composed of evenly distributed straight guide vanes and an outer shell. The inner edge of the deflection guide vane (71) of the upper guide wheel coincides with the axis of the upper guide wheel housing, and the outer edge is always in contact with the inner wall of the housing and deflects at a certain angle in the circumferential direction; the inner edge of the straight guide vane (61) of the lower guide wheel coincides with the axis of the lower guide wheel housing, the outer edge is parallel to the inner edge and is in close contact with the inner wall of the housing.

2. According to claim 1, the guide vane of the upper guide wheel (7) is a deflection guide vane, and the deflection direction and deflection angle of the deflection guide vane (71 or 73) are calculated and determined according to the installation position of the upper guide wheel and the arrangement of the distributor piping system.

3. According to claim 1, the guide vane of the lower guide wheel (6) is a straight guide vane, and the height of the straight guide vane (61) is determined by calculation.

4. According to claim 1, the number of guide vanes of the guide wheel is not less than 2, and the number of guide vanes of both the upper guide wheel and the lower guide wheel is determined by calculation.

5. According to claim 1, the distribution device has the following two installation methods, including: ① Split installation: The upper guide wheel (7) is located slightly behind the inlet of the vertical flue gas pipe (3), and the leading edge of one set of deflecting guide vanes (71) (i.e., two symmetrically distributed deflecting guide vanes) is aligned with the axis of the horizontal flue gas pipe; the lower guide wheel (6) is located at the inlet of the flue gas distributor (4), and the leading edge of one set of straight guide vanes (61) (i.e., two symmetrically distributed straight guide vanes) is along the left and right symmetrical planes of the flue gas distributor (4), and the bottom of the lower guide wheel (6) is the inlet of the flue gas distributor (4); ② Integrated installation: The trailing edge of the upper guide wheel deflecting guide vane (73) is connected to the leading edge of the straight guide vane (63) of the lower guide wheel (6) to form a combined guide vane, which shares a common outer cylinder (74) (or (64), becoming a composite guide wheel). The composite guide wheel is installed between the outlet of the vertical flue gas pipe (3) and the inlet of the flue gas distributor (4), ensuring that the leading edge line of one set of deflecting guide vanes of the upper guide wheel (7) (i.e., two symmetrically distributed deflecting guide vanes) is consistent with the axial direction of the horizontal flue gas pipe (1).

Images