Novel high-temperature air preheater

Abstract

The utility model provides a novel high-temperature air preheater which comprises a shell. A heat exchange tube is mounted in the shell and is supported by a partition plate; the shell is connected with the hot air inlet tube plate, the hot air outlet tube plate, the partition plate and the horizontal connecting plate into a whole; a smoke inlet non-metal expansion joint and a smoke outlet non-metal expansion joint are arranged on the two sides of the shell. A tubular structure is adopted, a medium in the tube is hot air, a medium outside the tube is high-temperature flue gas, the inlet temperature of the hot air is 280 DEG C, the outlet temperature of the hot air is 420 DEG C, the inlet temperature of the high-temperature flue gas is 550 DEG C, and the outlet temperature of the high-temperature flue gas is 430 DEG C. A high-temperature air preheater adopts external heat preservation, a heat exchange tube is horizontally arranged, and the hot air and the high-temperature flue gas adopt cross flow heat exchange. Non-metal expansion joints are arranged at flue gas side inlet and outlet flanges and air side inlet and outlet tube plates of the high-temperature air preheater to absorb expansion of the high-temperature air preheater in all directions and absorb vibration generated by high-speed flowing of media at the same time.

Description

Technical Field

[0001] This utility model belongs to the field of high-temperature air preheaters, and specifically relates to a novel high-temperature air preheater. Background Technology

[0002] The alkane dehydrogenation to olefins process generates a large amount of high-temperature waste heat, which is generally recovered through waste heat boilers. Since this process requires a large amount of high-temperature hot air, taking a 600,000-ton / year alkane dehydrogenation process as an example, it requires about 1,000 tons / hour of high-temperature hot air at around 420°C. Therefore, if the process waste heat energy can be converted into high-temperature hot air heat, the natural gas consumption in the downstream process heating furnace can be reduced. For every 1°C increase in hot air temperature, approximately 30 Nm3 / h of natural gas can be saved, thereby creating huge economic benefits for enterprises. However, due to the high temperature of the process waste heat and hot air, the thermal expansion problem between the heat exchange tubes and the shell is difficult to solve, so traditional low-temperature air preheaters cannot be used.

[0003] In recent years, the alkane dehydrogenation to olefins process has been widely promoted in China. This process is favored by chemical companies due to its low investment, short construction period, and high profits. Taking a 600,000-ton / year alkane dehydrogenation process as an example, after the dehydrogenation reaction is completed, the reactor discharges a large amount of high-temperature waste heat, typically around 570℃, with a flue gas flow rate of approximately 1100 t / h. Discharging such a large amount of high-temperature waste heat into the atmosphere would result in a huge waste of energy and environmental pollution. Therefore, a waste heat boiler is needed to recover the heat. However, waste heat boilers generally produce medium-temperature, medium-pressure superheated steam. Some chemical companies do not have a large demand for superheated steam, but they have a large demand for high-temperature hot air. For example, in a 600,000-ton / year alkane dehydrogenation process, the high-temperature hot air requirement is approximately 1000 t / h, requiring a hot air temperature of 420℃. Therefore, a high-temperature air preheater is needed to convert waste heat energy into air heat. Traditional low-temperature air preheaters cannot solve the thermal expansion problem when used at high temperatures. A new type of high-temperature air preheater with a special structure is needed to solve the problem of thermal expansion between the heat exchange tubes and the shell. Utility Model Content

[0004] The purpose of this invention is to provide a novel high-temperature air preheater that solves the problem of thermal expansion between the heat exchange tube and the shell.

[0005] A novel high-temperature air preheater includes a shell; heat exchange tubes are installed inside the shell and supported by a partition; the shell is integrated with a hot air inlet tube sheet, a hot air outlet tube sheet, a partition, and a horizontal connecting plate; a flue gas inlet non-metallic expansion joint and a flue gas outlet non-metallic expansion joint are provided on both sides of the shell.

[0006] Furthermore, both the flue gas inlet non-metallic expansion joint and the flue gas outlet non-metallic expansion joint are provided with two flue gas inlet non-metallic expansion joint flanges, which are respectively connected to the waste heat boiler flue and the shell.

[0007] Furthermore, the shell material is 12Cr1MoV, and when in contact with high-temperature flue gas, the expansion amount along the flue gas flow direction is 35mm.

[0008] Furthermore, the heat exchange tube is made of 12Cr1MoVG material.

[0009] Furthermore, the hot air inlet tube sheet and the hot air outlet tube sheet are made of 12Cr1MoV material, and the heat exchange tubes are welded to the hot air inlet tube sheet and the hot air outlet tube sheet.

[0010] Furthermore, the hot air inlet tube sheet and the hot air outlet tube sheet are respectively provided with a hot air inlet non-metallic expansion joint and a hot air outlet non-metallic expansion joint.

[0011] Furthermore, the shell and heat exchange tube are 7-8m long, the shell expands by 65mm along the length of the heat exchange tube, and the heat exchange tube expands by 40mm along the length.

[0012] Furthermore, the diameter of the heat exchange tube is Ф32-Ф48.

[0013] The beneficial effects of this utility model are as follows:

[0014] 1. This utility model sets non-metallic expansion joints at both ends of the tube sheet of the high-temperature air preheater. The tube sheet serves as both a flange on one side of the non-metallic expansion joint and part of the high-temperature air preheater for fixing the heat exchange tubes. This unique structure can effectively solve the problem of expansion difference between the heat exchange tubes and the shell in the length direction of the heat exchange tubes under high temperature conditions (when both the flue gas side medium temperature and the air side medium temperature are high), and avoid cracking of the air preheater due to expansion difference.

[0015] 2. This utility model provides non-metallic expansion joints at both ends of the flue gas side of the high-temperature air preheater, which can solve the problem of the shell expanding along the flue gas direction under high temperature conditions (when both the flue gas side medium temperature and the air side medium temperature are high), and avoid cracking of the air preheater due to expansion.

[0016] 3. This invention can effectively absorb vibrations caused by high flue gas velocity and high air velocity.

[0017] 4. The high-temperature air preheater of this utility model has high flue gas velocity and high air velocity, which can enhance heat exchange and reduce the size of the equipment.

[0018] 5. In this utility model of high-temperature air preheater, the heat exchange medium, high-temperature flue gas and hot air, adopt a cross-flow, which can enhance heat exchange.

[0019] 6. This invention converts the high-temperature flue gas waste heat energy generated in the process into hot air heat. Due to the constraints of the waste heat boiler cross-sectional size and heat exchange requirements, the flue gas side cross-sectional size of the high-temperature air preheater is relatively large, and the heat exchange tube is relatively long, making it difficult to solve the problem of thermal expansion between the heat exchange tube and the shell. This invention develops a high-temperature air preheater suitable for alkane dehydrogenation waste heat boilers, which can effectively solve the thermal expansion problem. At the same time, in order to enhance heat exchange, the air velocity inside the tube and the flue gas velocity outside the tube are selected to be relatively high during the development process. The air velocity inside the tube reaches 35-45 m / s, and the flue gas velocity outside the tube reaches 20-30 m / s. While the high velocity enhances heat exchange, it can also cause vibration of the high-temperature air preheater. This invention can solve this problem simultaneously. Attached Figure Description

[0020] Figure 1 This is a top view of the present invention;

[0021] Figure 2 This is a structural diagram of the hot air inlet tube sheet and the hot air outlet tube sheet of this utility model. Detailed Implementation

[0022] The present invention will now be further described with reference to the accompanying drawings.

[0023] like Figure 1 As shown, a novel high-temperature air preheater includes a high-temperature flue gas flow and a hot air flow.

[0024] 1. High-temperature flue gas process

[0025] High-temperature flue gas at 550°C enters the flue gas inlet non-metallic expansion joint 14 from the left side of the high-temperature air preheater, flows horizontally through the heat exchange tube 1, and after exchanging heat with the heat exchange tube 1, heats the hot air inside the heat exchange tube 1 from 280°C to 420°C, and then flows out of the high-temperature air preheater through the flue gas outlet non-metallic expansion joint 6.

[0026] The flue gas inlet non-metallic expansion joint flange A13 is connected to the waste heat boiler flue, the flue gas inlet non-metallic expansion joint flange B15 is connected to the shell 16, the flue gas outlet non-metallic expansion joint flange A5 is connected to the shell 16, and the flue gas outlet non-metallic expansion joint flange 7 is connected to the waste heat boiler flue.

[0027] The shell 16 is made of 12Cr1MoV material and is in direct contact with high-temperature flue gas. The expansion amount along the flue gas flow direction is 35mm. The non-metallic expansion joint 14 at the flue gas inlet and the non-metallic expansion joint 6 at the flue gas outlet can effectively absorb the expansion amount in this direction and prevent the shell 16 from cracking.

[0028] To enhance heat exchange, the high-temperature flue gas flows horizontally across the heat exchange tube at a velocity of 20 m / s to 30 m / s. The high-speed flow of the flue gas will cause vibration in the high-temperature air preheater. The non-metallic expansion joint 14 at the flue gas inlet and the non-metallic expansion joint 6 at the flue gas outlet can effectively absorb the vibration.

[0029] 2. Hot air flow

[0030] High-temperature hot air at 280°C enters heat exchange tube 1 from the end of heat exchange tube 1 at the hot air inlet tube sheet 2, is heated to 420°C inside heat exchange tube 1, and then flows out of heat exchange tube 1.

[0031] The hot air inlet tube sheet 2 serves as both a side flange of the hot air inlet non-metallic expansion joint 3 and part of the high-temperature air preheater. The hot air inlet non-metallic expansion joint flange 4 is connected to the shell 16.

[0032] The heat exchange tube 1 is made of 12Cr1MoVG, and the hot air inlet tube sheet 2 and hot air outlet tube sheet 12 are made of 12Cr1MoV. The heat exchange tube 1 is connected to the hot air inlet tube sheet 2 and the hot air outlet tube sheet 12 by welding. Heat treatment is required before and after welding.

[0033] The partition 9 is welded to the shell 16 using intermittent welding. The heat exchange tube 1 passes horizontally through the partition 9 without being welded to it. The partition 9 serves to support the heat exchange tube 1.

[0034] The four partitions are connected by horizontal connecting plates 8 using intermittent welding.

[0035] The hot air inlet tube sheet 2, the hot air outlet tube sheet 12, the partition 9, the horizontal connecting plate 8, and the shell 16 are connected as a whole.

[0036] The shell 16 and the heat exchange tube 1 are 7-8m long. The shell 16 expands by 65mm in the length direction of the heat exchange tube, and the heat exchange tube 1 expands by 40mm in the length direction. The expansion difference between the two is 25mm. This expansion is absorbed by the non-metallic expansion joint 3 at the hot air inlet and the non-metallic expansion joint 11 at the hot air outlet, which can effectively solve the problem of cracking of the high-temperature air preheater caused by the expansion difference.

[0037] The hot air velocity inside heat exchange tube 1 is 35-45 m / s. High velocity will cause vibration of the high-temperature air preheater. The non-metallic expansion joint 3 at the hot air inlet and the non-metallic expansion joint 11 at the hot air outlet can effectively absorb the vibration.

[0038] This utility model's high-temperature air preheater adopts a tubular structure, with hot air inside the tubes and high-temperature flue gas outside. The inlet temperature of the hot air is about 280℃ and the outlet temperature is about 420℃, while the inlet temperature of the high-temperature flue gas is about 550℃ and the outlet temperature is about 430℃. The high-temperature air preheater is externally insulated, and the heat exchange tubes are arranged horizontally. The hot air and high-temperature flue gas exchange heat through a cross-flow. Non-metallic expansion joints are installed at the flue gas side inlet and outlet flanges and the air side inlet and outlet tube sheets of the high-temperature air preheater to absorb the expansion of the high-temperature air preheater in all directions and to absorb the vibration generated by the high-speed flow of the medium.

[0039] This utility model's high-temperature air preheater is equipped with non-metallic expansion joints at both the flue gas inlet and outlet, as well as the air inlet and outlet. These joints effectively absorb expansion in all directions, solving the thermal expansion problem of the high-temperature air preheater, and also effectively absorb vibrations generated by high-speed hot air and flue gas flow. Based on the cross-sectional dimensions and layout requirements of the waste heat boiler, the heat exchange tubes of this high-temperature air preheater are arranged horizontally, with high-temperature flue gas entering from the left and exiting from the right, and hot air entering from the front and exiting from the rear, employing a cross-flow heat exchange method to enhance heat transfer.

[0040] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A novel high-temperature air preheater, characterized in that, It includes a shell (16); heat exchange tubes (1) are installed inside the shell (16) and supported by a partition (9); the shell (16) is connected as a whole with a hot air inlet tube sheet (2), a hot air outlet tube sheet (12), a partition (9) and a horizontal connecting plate (8); a flue gas inlet non-metallic expansion joint (14) and a flue gas outlet non-metallic expansion joint (6) are provided on both sides of the shell (16).

2. The novel high-temperature air preheater according to claim 1, characterized in that, Both the flue gas inlet non-metallic expansion joint (14) and the flue gas outlet non-metallic expansion joint (6) are provided with two flue gas inlet non-metallic expansion joint flanges, which are respectively connected to the waste heat boiler flue and the shell (16).

3. A novel high-temperature air preheater according to claim 1, characterized in that, The shell (16) is made of 12Cr1MoV and is in contact with high-temperature flue gas. Its expansion amount along the flue gas flow direction is 35mm.

4. A novel high-temperature air preheater according to claim 1, characterized in that, The heat exchange tube (1) is made of 12Cr1MoVG material.

5. A novel high-temperature air preheater according to claim 1, characterized in that, The hot air inlet tube sheet (2) and hot air outlet tube sheet (12) are made of 12Cr1MoV material, and the heat exchange tube (1) is welded to the hot air inlet tube sheet (2) and hot air outlet tube sheet (12).

6. A novel high-temperature air preheater according to claim 1, characterized in that, The hot air inlet tube sheet (2) and the hot air outlet tube sheet (12) are respectively provided with a hot air inlet non-metallic expansion joint (3) and a hot air outlet non-metallic expansion joint (11).

7. A novel high-temperature air preheater according to claim 1, characterized in that, The shell (16) and heat exchange tube (1) are 7-8m long. The shell (16) expands by 65mm in the length direction of the heat exchange tube, and the heat exchange tube (1) expands by 40mm in the length direction.

8. A novel high-temperature air preheater according to claim 1, characterized in that, The diameter of the heat exchange tube (1) is Ф32-Ф48.

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