Air preheater for bottom burner of ethylene cracking furnace

Abstract

The utility model discloses an air preheater for a burner at the bottom of an ethylene cracking furnace, and relates to the field of ethylene cracking, the air preheater comprises an air preheater body and a connecting air duct, the air preheater body comprises a preheater shell, an air inlet and an air outlet are formed in the two ends of the preheater shell respectively, and a heat exchange tube bundle is arranged in the preheater shell; a heat source inlet and a heat source outlet are formed in the preheater shell and connected to the two ends of the heat exchange tube bundle correspondingly. The air outlet is connected to a combustor at the bottom of the cracking furnace through a connecting air duct; one air preheater body is matched with a plurality of cracking furnace bottom combustors. The cracking furnace solves the problem that the bottom space of the cracking furnace is limited, is suitable for limited space, saves occupied area and is high in heat exchange efficiency.

Description

TECHNICAL FIELD

[0001] The utility model relates to an air preheater for ethylene cracking furnace bottom burner, aims at heating the combustion air of ethylene cracking furnace bottom burner. BACKGROUND

[0002] Ethylene cracking furnace is a big energy consumer of ethylene cracking process, accounts for more than 50% of the energy consumption of the whole ethylene plant area, at present, all the ethylene plants in China are carrying out research on the energy saving and consumption reduction of ethylene cracking furnace. In recent years, in the newly built ethylene refining integrated project, the cracking furnace bottom burner air preheating energy saving technology is adopted, the air preheater is additionally arranged at the inlet of the cracking furnace bottom burner, the low-temperature waste heat (circulating quenching water, various condensates, process hot water, etc.) of the device area is utilized to preheat the combustion air entering the burner, on the one hand, the fuel gas consumption is reduced, the carbon dioxide emission is reduced, and the overall thermal efficiency of the cracking furnace is improved. On the other hand, the low-temperature waste heat is recycled, and the technology has achieved good energy saving and emission reduction effect, and is widely applied to ethylene cracking furnaces.

[0003] However, part of the early built ethylene cracking furnaces do not consider arranging the air preheater at the bottom burner in the initial design, the cracking furnace bottom is arranged with fuel gas pipelines, nitrogen reduction steam pipelines, decoking gas pipelines, burner adjusting connecting rods and various pipelines, and the space condition of the furnace bottom is relatively nervous, which brings great difficulty to additionally arrange the air preheater. UTILITY MODEL CONTENT

[0004] The technical problem solved by the present application is to overcome the shortcomings of the prior art, provide an air preheater for ethylene cracking furnace bottom burner, solve the problem of tight space at the bottom of the cracking furnace, and be suitable for limited space, save land occupation and have high heat exchange efficiency.

[0005] The technical scheme provided by the present application is as follows:

[0006] An air preheater for ethylene cracking furnace bottom burner, comprising an air preheater body and a connecting air duct, the air preheater body comprises a preheater shell, both ends of the preheater shell are an air inlet and an air outlet respectively, a heat exchange tube bundle is arranged in the preheater shell, a heat source inlet and a heat source outlet are arranged on the preheater shell, and the heat source inlet and the heat source outlet are connected to both ends of the heat exchange tube bundle respectively; the air outlet is connected to the cracking furnace bottom burner through the connecting air duct; one air preheater body is matched with more than one cracking furnace bottom burner.

[0007] The connecting air duct comprises an air duct inlet, a distribution air duct, an air duct outlet, pressure detection and an adjusting distributor, the air duct inlet is connected with the air outlet, the air duct outlet is connected with the bottom burner of the cracking furnace, the air duct inlet and the air duct outlet are connected by the distribution air duct, the number of the air duct inlets is the same as the number of the preheater bodies, the number of the air duct outlets is the same as the number of the matched bottom burners of the cracking furnace, the pressure detection is arranged on each air duct outlet and is used for detecting the pressure in the air duct outlet, and the adjusting distributor is arranged in the distribution air duct and is located between adjacent air duct outlets and is used for adjusting the distribution of the heated air so that the pressure of each air duct outlet is consistent.

[0008] The adjusting distributor comprises an adjusting shaft and an air adjusting plate, the adjusting shaft penetrates through the distribution air duct and is rotationally connected with the distribution air duct, and the air adjusting plate is located in the distribution air duct and is fixedly connected with the adjusting shaft.

[0009] A scale dial is arranged outside the distribution air duct, a pointer is arranged on the adjusting shaft, and the opening degree of the air adjusting plate is determined by the relative positions of the pointer and the scale dial.

[0010] A distribution air plate is arranged at the inlet of the distribution air duct, and the distribution air plate is a porous plate.

[0011] The heat exchange tube bundle comprises a base pipe, fins and turbulence elements, the fins are connected to the outer wall of the base pipe, the inner wall surface of the base pipe is provided with a plurality of turbulence elements, each turbulence element comprises a plurality of cyclone blades, and the heat source generates a cyclone after passing through the heat exchange tube bundle.

[0012] The turbulence elements are arranged at intervals inside the base pipe, and the interval distance between adjacent two turbulence elements is 0.2-0.6 m.

[0013] An air filter screen is arranged at the air inlet of the preheater shell, the air filter screen is used for filtering air, the preheater shell is provided with a support, and the air filter screen is slidingly connected with the support so as to be easily pulled out.

[0014] A soot blowing device is arranged on the side of the air filter screen away from the air inlet direction, the soot blowing device comprises a soot blowing interface, a soot blowing manifold and a blowing nozzle, the soot blowing manifold is arranged in multiple rows, a plurality of blowing nozzles are arranged on each row, the blowing nozzles blow the air filter screen, and the soot blowing interface is used for connecting the soot blowing manifold with a blowing medium conveying pipeline.

[0015] The heat source inlet is used for the inflow of the heat source, the heat source flows out from the heat source outlet after passing through the heat exchange tube bundle, the air inlet is used for the inflow of air, the air flows out from the air outlet after being heated by the heat exchange tube bundle, and the flow direction of the heat source and the flow direction of the air are in a counterflow mode.

[0016] In summary, the present application at least has the following beneficial technical effects:

[0017] The utility model relates to an air preheater for ethylene cracking furnace bottom burner, adopt a preheater body, match the type of multiple cracking furnace bottom burners, be applicable to the case that cracking furnace bottom space is nervous. The form of connecting air flue is according to the number of air preheater body and matched cracking furnace bottom burner, and sets up distribution air flue, carries out uniform distribution to combustion air. Heat exchange tube bundle adopts finned tube type, and the fin adopts the material such as aluminium or copper of high heat exchange coefficient, has higher heat exchange efficiency, in the heat exchange tube, interval sets up multiple turbulence elements, and the cyclone blade on turbulence element can make fluid produce rotating flow, enhances heat exchange effect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the "one pair of two" type front view schematic drawing of the air preheater example of the utility model.

[0019] Figure 2 It is the "two pairs of three" type front view schematic drawing of the air preheater example of the utility model.

[0020] Figure 3 It is the side view schematic drawing of the air preheater of the utility model.

[0021] Figure 4 It is the schematic drawing of heat exchange tube bundle and turbulence element of the utility model.

[0022] Figure 5 It is the schematic drawing of cyclone blade of the utility model.

[0023] BRIEF DESCRIPTION OF DRAWINGS: 1 - support, 2 - air inlet, 3 - heat source outlet, 4 - preheater shell, 5 - heat source inlet, 6 - air outlet, 7 - air flue inlet, 8 - temperature detection, 9 - spare air door, 10 - air flue outlet, 11 - pressure detection, 12 - regulating distributor, 13 - distribution air flue, 14 - tube sheet, 15 - air distribution plate, 16 - soot blowing manifold, 17 - soot blowing interface, 18 - purging spray head, 19 - air filter screen, 20 - heat exchange tube bundle, 21 - turbulence element, 22 - fin, 23 - base pipe, 24 - cyclone blade. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantage of the utility model more clear, the following will combine the attached drawing, and the embodiment disclosed by the utility model is further described in detail.

[0025] The embodiment of the application discloses an air preheater for ethylene cracking furnace bottom burner, as shown in Figure 1 And Figure 2 Shown, including preheater body, connecting air flue, air filter screen, soot blowing device and support.

[0026] The corresponding mode of the preheater body and the bottom burner of the cracking furnace is that one air preheater body matches multiple bottom burners of the cracking furnace, or multiple air preheater bodies match multiple bottom burners of the cracking furnace, but the number of the bottom burners of the cracking furnace is greater than that of the air preheater bodies.

[0027] As shown in Figure 1 , the air preheater body is used for heat exchange between the heat source and the combustion air, and the air preheater body comprises a preheater shell 4, a heat exchange tube bundle 20 arranged in the preheater shell 4, a heat source inlet 5, a heat source outlet 3, an air inlet 2, an air outlet 6, a soot blowing device and the like. The heat source enters the preheater shell 4 from the heat source inlet 5, heats the air through the heat exchange tube bundle 20, and then flows out of the air preheater through the heat source outlet 3. The combustion air enters from the air inlet 2, flows out from the air outlet 6 after being heated, enters the connecting air duct, and enters the bottom burner of the cracking furnace through the connecting air duct. The flow direction of the heat source and the flow direction of the air are in counterflow mode.

[0028] The capacity of the air preheater body is designed to meet the simultaneous operation of multiple bottom burners of the cracking furnace, as shown in Figure 1 , generally, one air preheater body matches two bottom burners, that is, a “one-to-two” type, as shown in Figure 2 , two air preheater bodies match three bottom burners, that is, a “two-to-three” type. The scheme of matching multiple bottom burners with one air preheater occupies less space and can effectively solve the problem of tight space of the bottom of the cracking furnace.

[0029] As shown in Figure 4 , the heat exchange tube bundle 20 adopts a finned tube, which is composed of a base pipe 23, a fin 22 and a turbulence element 21. The fin 22 is made of aluminum or copper and has a high heat exchange coefficient to improve the heat exchange efficiency. The base pipe 23 is circular or elliptical in shape. The heat exchange tube bundle 20 is arranged in multiple layers, and multiple turbulence elements 21 are arranged inside the heat exchange tube bundle 20. The adjacent two turbulence elements 21 are spaced apart by 0.2-0.6 m. Each turbulence element contains multiple cyclone blades 24, which can enhance the heat exchange effect without increasing excessive pressure loss, as shown in Figure 5 .

[0030] The air filter screen 19 is made of stainless steel woven mesh with a mesh size of 4-10, which is used to block impurities such as flying fibers and dust in the air to prevent the heat exchange tube bundle from being blocked and affecting the normal operation of the preheater. The air filter screen 19 is located at the air inlet 2 of the preheater body, and the bracket 1 is placed at the bottom of the preheater to support the preheater. The air filter screen 19 is placed on the support member pre-welded on the bracket 1, and a handle is provided to pull out the air filter screen 19 for cleaning and purging of the filter screen.

[0031] AsFigure 3 The soot blowing device is arranged above the air filter screen 19 and consists of a soot blowing interface 17, a soot blowing manifold 16 and a blowing nozzle 18. The soot blowing interface 17 is in the form of a flange and is connected to a blowing medium conveying pipe. The soot blowing interface 17 is used to connect the soot blowing manifold 16 so that the blowing medium enters the soot blowing manifold 16 from the blowing medium conveying pipe. The soot blowing manifold 16 is arranged in multiple rows, and multiple blowing nozzles 18 are arranged above each row. The blowing nozzles 18 blow the air filter screen 19, and the medium used is compressed air or low-pressure steam.

[0032] The connecting air duct is used to connect the preheater body and the cracking furnace bottom burner and to deliver the heated combustion air to the inlet of the cracking furnace bottom burner. The connecting air duct is provided with an air duct inlet 7, a distribution air duct 13, an air duct outlet 10, a pressure detector 11, a temperature detector 8, an adjusting distributor 12 and a standby air door 9. The air duct inlet 7 is connected to the air outlet 6 of the preheater body, and the number of the air duct inlets 7 is the same as that of the preheater body. The air duct outlet 10 is connected to the inlet of the cracking furnace bottom burner, and the number of the air duct outlets 10 is the same as that of the matched cracking furnace bottom burners. The distribution air duct 13 is arranged between the air duct inlet 7 and the air duct outlet 10. The distribution air duct 13 is provided with a wind distribution plate and the adjusting distributor 12. The wind distribution plate is in the form of a multiple-hole plate regularly distributed in a certain proportion, is located at the inlet of the distribution air duct 13, is fixedly connected to the inner wall of the distribution air duct 13 and is arranged perpendicularly to the flow direction of the combustion air. The adjusting distributor 12 is located between two adjacent air duct outlets 10. The adjusting distributor 12 comprises an adjusting shaft and an air adjusting plate. The adjusting shaft vertically penetrates the distribution air duct 13 and is rotationally connected to the distribution air duct 13. The air adjusting plate is located in the distribution air duct 13 and is fixedly connected to the adjusting shaft. The adjusting shaft is rotated to drive the air adjusting plate to rotate, so that the air adjusting plate is in contact with or separated from the inner wall of the distribution air duct 13 to adjust the opening degree of the distribution air duct 13. The heated combustion air flowing out of the air outlet 6 enters the distribution air duct 13 from the air duct inlet 7 and can be further adjusted in the distribution amount in the two adjacent air duct outlets 10 by the air adjusting plate. A scale disc is arranged outside the distribution air duct 13, a pointer is arranged on the adjusting shaft, and the opening degree of the air adjusting plate can be determined by the relative position of the pointer and the scale disc. The pressure detector 11 is arranged on each air duct outlet 10, and the adjusting distributor 12 is arranged on the distribution air duct 13. The adjusting distributor 12 is adjusted according to the pressure value of the pressure detector 11 to make the pressure of each air duct outlet 10 consistent, so as to realize the uniform distribution of the combustion air and satisfy the uniform consistency of the air flow of each burner. The temperature detector 8 is arranged on each air duct outlet 10 to directly display the temperature of the preheated air. The standby air door 9 is arranged on the connecting air duct. When the air preheater is blocked, the standby air door can be opened to supplement the insufficient air and maintain the normal working state of the burner.

[0033] Figure 1 In the "one-to-two" type shown, the air duct inlet 7 is provided as one, connected with the air outlet 6 of the preheater body, and the air duct outlet 10 is provided as two, respectively connected with the inlets of the two bottom burners of the cracking furnace. Figure 2 In the "two-to-three" type shown, the air duct inlet 7 is provided as two, connected with the air outlet 6 of the preheater body, and the air duct outlet 10 is provided as three, respectively connected with the inlets of the three bottom burners of the cracking furnace.

[0034] The accompanying drawings are used to further illustrate the present application. Figure 1 , the accompanying drawings are used to further illustrate the present application. Figure 2 The present application is described by two common types, but these two types are exemplary and only serve to illustrate. On this basis, the present application can be replaced and improved in many ways, all of which fall within the scope of the present application.

[0035] The contents not described in detail in the present application specification are well-known to those skilled in the art.

[0036] The present application is described in detail above in combination with specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be replaced, modified or improved in many ways without deviating from the spirit and scope of the present application, and all of these fall within the scope of the present application. The scope of protection of the present application is subject to the appended claims.

Claims

1. An air preheater for the bottom burner of an ethylene cracking furnace, characterized in that: The air preheater body includes an air preheater body and a connecting air duct. The air preheater body includes a preheater shell (4), with an air inlet (2) and an air outlet (6) at its two ends. A heat exchange tube bundle (20) is provided inside the preheater shell (4), and a heat source inlet (5) and a heat source outlet (3) are provided on the preheater shell (4). The heat source inlet (5) and the heat source outlet (3) are respectively connected to the two ends of the heat exchange tube bundle (20). The air outlet (6) is connected to the burner at the bottom of the pyrolysis furnace through the connecting air duct. One air preheater body is matched with multiple bottom burners of pyrolysis furnaces.

2. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 1, characterized in that, The connecting air duct includes: an air duct inlet (7), a distribution air duct (13), an air duct outlet (10), a pressure sensor (11), and a regulating distributor (12). The air duct inlet (7) is connected to the air outlet (6), and the air duct outlet (10) is connected to the bottom burner of the pyrolysis furnace. The distribution air duct (13) is located between the air duct inlet (7) and the air duct outlet (10). The number of air duct inlets (7) is the same as the number of preheater bodies, and the number of air duct outlets (10) is the same as the number of matching bottom burners of the pyrolysis furnace. A pressure sensor (11) is provided on each air duct outlet (10). The pressure sensor (11) is used to detect the pressure in the air duct outlet (10). The regulating distributor (12) is located in the distribution air duct (13) and between adjacent air duct outlets (10). The regulating distributor (12) is used to regulate the distribution of heated air so that the pressure of each air duct outlet (10) is consistent.

3. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 2, characterized in that: The regulating distributor (12) includes an regulating shaft and an air regulating plate. The regulating shaft passes through the distribution air duct (13) and is rotatably connected to the distribution air duct (13). The air regulating plate is located inside the distribution air duct (13) and is fixedly connected to the regulating shaft.

4. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 3, characterized in that: A scale is provided outside the distribution air duct (13), and a pointer is provided on the adjustment shaft. The opening degree of the air regulating plate is determined by the relative position of the pointer and the scale.

5. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 2, characterized in that: An air distribution plate is provided at the inlet of the distribution air duct (13), and the air distribution plate is a perforated plate.

6. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 1, characterized in that: The heat exchange tube bundle (20) includes a base tube (23), fins (22) and a flow-turbing element (21). The fins (22) are connected to the outer wall of the base tube (23). Multiple flow-turbing elements (21) are provided on the inner wall of the base tube (23). Each flow-turbing element (21) includes multiple swirling blades (24) to generate swirling flow after the heat source passes through the heat exchange tube bundle (20).

7. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 6, characterized in that: The turbulence-disrupting elements (21) are spaced apart inside the base tube (23), with a spacing of 0.2~0.6m between two adjacent turbulence-disrupting elements (21).

8. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 1, characterized in that: An air filter (19) is provided at the air inlet (2) of the preheater shell (4) for filtering air; the preheater shell (4) is provided with a bracket (1), and the air filter (19) is slidably connected to the bracket (1) so that the air filter (19) can be pulled out.

9. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 8, characterized in that: The air filter (19) has a soot blowing device arranged on the side opposite to the air intake direction. The soot blowing device includes a soot blowing interface (17), a soot blowing manifold (16), and a purging nozzle (18). The soot blowing manifold (16) is arranged in multiple rows, with multiple purging nozzles (18) arranged on each row. The purging nozzles (18) purify the air filter (19). The soot blowing interface (17) is used to connect the soot blowing manifold (16) to the purging medium conveying pipeline.

10. An air preheater for a bottom burner of an ethylene cracking furnace according to claim 1, characterized in that: The heat source inlet (5) is used for the inflow of heat source. The heat source flows out from the heat source outlet (3) through the heat exchange tube bundle (20). The air inlet (2) is used for the inflow of air. After the air is heated by the heat exchange tube bundle (20), it flows out from the air outlet (6). The flow direction of the heat source and the flow direction of the air are in a counter-current manner.

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