CN212456946U

CN212456946U - High-efficient preheater that cooperation radiant tube nozzle used

Info

Publication number: CN212456946U
Application number: CN202021812263.XU
Authority: CN
Inventors: 芮州峰; 程奇伯; 王宏宇; 张道明; 冯霄红; 雍海泉
Original assignee: Chongqing CISDI Thermal and Environmental Engineering Co Ltd
Current assignee: Chongqing CISDI Thermal and Environmental Engineering Co Ltd
Priority date: 2020-08-26
Filing date: 2020-08-26
Publication date: 2021-02-02
Anticipated expiration: 2030-08-26

Abstract

The utility model belongs to the technical field of metallurgy, and relates to a high-efficiency preheater matched with radiant tube burners for use, which comprises a cold air inlet, a preheated mixed combustion-supporting gas outlet, a smoke exhaust outlet, an air distribution chamber, an air tube bundle, an air collection chamber and an air-smoke mixed central tube which are arranged in a shell, wherein the air distribution chamber is connected with the cold air inlet, two ends of the air tube bundle are respectively connected with the air collection chamber and the air distribution chamber, one end of the air-smoke mixed central tube is connected with the preheated mixed combustion-supporting gas outlet, the other end of the air-smoke mixed central tube is stretched into the air high-speed spray tube of the air collection chamber and is communicated with the air high-speed spray tube of the air collection chamber and, one end of the heat insulation sleeve is blocked by the air distribution chamber, a seam is left between the other end of the heat insulation sleeve and the outer wall of the air high-speed spray pipe, and a horn mouth which is a tapered conical surface along the smoke flowing direction is formed at the end part on the same side of the air-smoke mixing central pipe. The utility model has the advantages of light weight, simple process and low manufacturing cost.

Description

High-efficient preheater that cooperation radiant tube nozzle used

Technical Field

The utility model belongs to the technical field of air preheating device, a high-efficient pre-heater that cooperation radiant tube nozzle used is related to, especially air preheating device that cooperation W/U type radiant tube nozzle used.

Background

Energy saving effect of industrial equipment and reduction of NO_XThe effect of discharging pollutants becomes an important index concerned by industrial production enterprises. In the metal heat treatment industry, in order to prevent the surface of a metal product from directly contacting with flue gas with complex chemical components, a radiation tube indirect heating mode is usually adopted, W-shaped and U-shaped radiation tubes are two commonly used radiation tubes, and the temperature uniformity of the tube wall of each radiation tube is one of important factors influencing the heat treatment effect.

In order to improve the heat transfer coefficient, a common air preheating device matched with a W/U-shaped radiant tube burner is generally in a mode of adopting a finned tube or a corrugated tube, and the improvement of the heat transfer coefficient is limited; meanwhile, the finned tubes and the corrugated tubes are usually processed in a casting mode, the processing technology is complex, the yield is low, and the tube walls are thick, so that the whole preheating device is heavy, and the manufacturing cost of equipment is high. In addition, the conventional air preheating device used in cooperation with the W/U-shaped radiant tube burner is generally provided with a flue gas circulating device, and a part of flue gas is mixed into air so as to reduce the oxygen concentration of combustion-supporting gas, reduce the local high temperature of a combustion area and play a role in inhibiting the generation of NOx. The air preheating device with the flue gas circulation can be divided into two types, namely realizing flue gas backflow at the outlet of the preheating device (rear flue gas backflow) and realizing flue gas backflow at the inlet of the preheating device (front flue gas backflow). The adoption of a rear flue gas reflux mode has the following problems: because the flue gas backflow is realized at the outlet of the preheating device, the higher the flue gas circulation rate is, the larger the flue gas quantity passing through the preheating device is, and under the condition that the air quantity is not changed, the higher the flue gas temperature is, the lower the heat efficiency is; the service life of the preheating device is shorter due to the fact that the high-temperature smoke passing through the preheating device is more. The front flue gas backflow mode is adopted, the flue gas backflow in front of the preheating device is realized through a specially-made flue gas backflow piece, but the flue gas backflow piece is very complex in structure, high-grade heat-resistant steel or other heat-resistant materials are required to be used for casting, the yield is very low, and the cost is high.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model aims at providing a high-efficient preheater that cooperation radiant tube nozzle was used, through optimizing leading flue gas backflow circulation structure and fin heat transfer structure, solve the complicated, with high costs problem of structure in the leading flue gas backflow mode of preheater.

The utility model discloses a realize through following technical scheme:

the utility model provides a high-efficiency preheater matched with radiant tube burners, which comprises a cold air inlet, a preheated mixed combustion-supporting gas outlet and a smoke outlet which are arranged on a shell, and an air distribution chamber, an air tube bank, an air collection chamber and an air-smoke mixed central tube which are arranged in the shell, wherein the air distribution chamber is connected with the cold air inlet, two ends of the air tube bank are respectively connected with the air collection chamber and the air distribution chamber, one end of the air-smoke mixed central tube is connected with the preheated mixed combustion-supporting gas outlet, the other end of the air-smoke mixed central tube is extended into the air high-speed spray tube of the air collection chamber and is communicated with the air high-speed spray tube of the air collection chamber and forms a, one end of the heat insulation sleeve is blocked by the air distribution chamber, a seam is left between the other end of the heat insulation sleeve and the outer wall of the air high-speed spray pipe, and a horn mouth which is a tapered conical surface along the smoke flowing direction is formed at the end part on the same side of the air-smoke mixing central pipe.

Furthermore, the shape of the inner cavity space of the air distribution chamber is topologically equivalent to a ring, and the air distribution chamber is provided with an inlet connected with a cold air inlet and a plurality of outlets connected with an air tube bundle; the spatial shape of the inner cavity of the air collection chamber is topologically equivalent to a column shape, and the air collection chamber is provided with a plurality of inlets connected with the air pipe bundle and more than one outlet connected with the air high-speed nozzle; the number of the corresponding air high-speed spray pipes is more than one.

Further, the air distribution chamber and the air collection chamber are in communication through one or more rings of air tube bundles having a tube structure including, but not limited to, a straight tube bundle or a spiral tube bundle.

Further, the inside of the pipe of the air pipe bundle is provided with an insert for enhancing heat exchange, and the cross section of the insert comprises but is not limited to a straight line shape, a cross shape or a straight spiral shape.

Further, the corresponding end surface of the air collection chamber facing the smoke gas in the coming direction is provided with a convex surface for reducing the smoke gas flow resistance, and the convex surface comprises but is not limited to a spherical surface or an ellipsoidal surface; the outlet end face of the air collection chamber is provided with a flow guide surface for reducing the air flow resistance in the air chamber, and the flow guide surface comprises but is not limited to a conical surface.

Further, an air heat insulation interlayer is formed between the pipe wall of the heat insulation sleeve and the pipe wall of the air-smoke mixing central pipe, and the ratio of the outer diameter of the heat insulation sleeve to the inner diameter of the air-smoke mixing central pipe ranges from 1.5 to 3.

Furthermore, the ratio of the distance between the inlet end face and the outlet end face of the bell mouth and the inner diameter of the air-smoke mixing central pipe ranges from 0.8 to 1.2.

Furthermore, the outlet end of the high-speed air spray pipe extends into the bell mouth, and the ratio of the distance between the outlet end face of the high-speed air spray pipe and the inlet end face of the bell mouth to the inner diameter of the air-smoke mixing central pipe is within the range of 0.5-1.4.

Furthermore, the position of the smoke backflow inlet is between the end face of the outlet of the high-speed air spray pipe and the end face of the outlet of the air collection chamber, and the flow area of the smoke backflow inlet is not smaller than the flow cross-sectional area of the air-smoke mixing central pipe.

Furthermore, all set up on air tube bank and the insulation sleeve and have the breach and be parallel alternative interval distribution's flue gas vortex baffle with this breach, and air tube bank and insulation sleeve run through in flue gas vortex baffle.

The utility model has the advantages that:

1. the utility model discloses an optimize leading flue gas circulation structure to improve the finned heat exchanger structure, make equipment whole have processing technology simple, and draw and penetrate a structure weight and alleviate about 40%, equipment is whole to alleviate about more than 30%, is favorable to having reduced equipment cost.

2. The utility model discloses realize reducing combustion-supporting gas O in the leading flue gas backward flow of pre-heater₂When the temperature in the tube reaches a certain condition, the concentration can be matched with a specific burner to realize stable flameless combustion, so that NO is greatly reduced_XAnd (5) discharging.

3. Compared with a heat exchanger structure with a finned tube or a corrugated tube, the utility model greatly increases the heat exchange area under the condition of occupying the same space, and can lead the preheating temperature of the combustion-supporting gas to be higher; and compare in the structure that realizes the flue gas backward flow in the pre-heater export, realize the flue gas backward flow in the pre-heater entrance, its flue gas volume that flows through pre-heater and empty flue gas mixture heat transfer is still less, and under the certain condition of air quantity, preheating temperature, exhaust gas temperature is lower, and preheating temperature is higher, is favorable to flue gas waste heat recovery, compares and can energy-conserving about 10% in traditional structure.

4. The utility model discloses realize the flue gas backward flow at the pre-heater entry, make it can realize higher gas recirculation multiplying power under the same air inlet pressure. For example, under the conditions of the same flue gas reflux amount (30%) and the same preheating temperature (507 ℃) of combustion-supporting gas (air and injected flue gas mixed gas), the pressure required by an air inlet is reduced by more than 35%.

5. The utility model discloses owing to realized higher preheating temperature to can reach stable flameless combustion state under the intraductal temperature condition of lower radiant.

6. The utility model discloses when realizing stable flameless burning, radiant tube wall temperature is more even, can improve thermal treatment product quality.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and/or combinations particularly pointed out in the appended claims.

Drawings

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail with reference to the accompanying drawings, in which:

fig. 1 is a schematic sectional view of the internal structure of the embodiment of the present invention.

Fig. 2 is an enlarged schematic view of a part I in fig. 1.

FIG. 3 is a schematic view of the gas flow direction inside the preheater, wherein a is a perspective view, B is a side view, c is a sectional view taken along line A-A, and d is a sectional view taken along line B-B.

FIG. 4 is a schematic view of a system in which a preheater is used with burners on radiant tubes; a is a W-shaped radiant tube, and b is a U-shaped radiant tube.

FIG. 5 is a schematic view of an outer profile of the flue gas turbulator.

FIG. 6 is a schematic view of the arrangement of the straight tube bundles of the air tube bundle; a is four, and b is six.

FIG. 7 is a schematic diagram of the arrangement of the spiral tube bundles of the air tube bundle.

FIG. 8 is a schematic cross-sectional view of an insert in an air harness; a is in a straight line shape, b is in a cross shape, and c is in a straight spiral shape.

Reference numerals: the device comprises a shell 1, a cold air inlet 2, a preheated mixed combustion-supporting gas outlet 3, a smoke exhaust outlet 4, an air distribution chamber 5, an air tube bundle 6, an air collection chamber 7, an air-smoke mixed central tube 8, an air high-speed spray tube 9, a heat insulation sleeve 10, a bell mouth 11, a smoke backflow inlet 12 and a smoke turbulence baffle 13; an insert 61; and a notch 131.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the features in the following embodiments and examples may be combined with each other without conflict.

As shown in fig. 1 and 2, the utility model provides a high-efficiency preheater used with radiant tube burner, which comprises a casing 1, the casing 1 is provided with a cold air inlet 2, a preheated mixed combustion-supporting gas outlet 3 and a smoke outlet 4, the interface direction of the air, smoke and air-smoke mixture on the casing can be adjusted according to the pipe distribution condition, the casing 1 comprises an air distribution chamber 5, the inlet of the air distribution chamber 5 is connected with the cold air inlet 2 through a steel pipe, the outlet of the air distribution chamber 5 is connected with the inlet ends of a group of air pipe bundles 6, the outlet of the air pipe bundles 6 is connected with the inlet of an air collection chamber 7, the outlet of the air collection chamber 7 is connected with an air high-speed spray pipe 9 extending into an air-smoke mixed central pipe 8, the air-smoke mixed central pipe 8 is used for mixing air and smoke, a circular seam is not sealed between the inlet end face of the air-smoke mixed, there is heat insulating sleeve 10 outside empty cigarette mixed center tube 8, do not seal between the one end that heat insulating sleeve 10 is close to empty cigarette mixed center tube 8 entry and the outlet end face of air collection chamber 7 and leave the circumferential weld, heat insulating sleeve 10 is close to empty cigarette mixed center tube 8 entry one end and empty cigarette mixed center tube 8 entry end and is connected through the conical steel sheet or the reducing steel pipe along the convergent of flue gas flow direction, form the bell mouth 11 that the flue gas penetrated the entry, the space between bell mouth 11 and the outlet end face of air collection chamber 7 forms flue gas backward flow entry 12, flue gas backward flow entry 12 is located between collection chamber 7 outlet end face and the high-speed spray tube 9 outlet end face of air, empty cigarette mixed center tube 8 exit end and preheating mix combustion-supporting gas export 3 and pass through the steel pipe intercommunication. In addition, in consideration of the thermal expansion of the steel pipes, it is necessary to weld pipe expansion joints (not shown) on each of the air tube bundle 6, the air-smoke mixing center pipe 8, and the heat insulating sleeve 10 to prevent thermal expansion of the pipes. By adopting the scheme, compared with the commonly used finned tube preheater, the utility model has the advantages of light weight, simple process and low manufacturing cost; and the heat exchange efficiency is increased, and the air preheating temperature is improved.

In this embodiment, an air heat insulation interlayer is formed between the wall of the heat insulation sleeve 10 and the wall of the air-smoke mixing central tube 8, so as to prevent that when the injected smoke reaches a certain amount, the temperature of the gas in the air-smoke mixing central tube 8 is higher than that of the gas outside the air-smoke mixing central tube, which causes a large amount of heat release of the mixed gas in the air-smoke mixing central tube 8 to the gas outside the air-smoke mixing central tube, and reduces the efficiency of the; the ratio of the outer diameter of the heat insulation sleeve 10 to the inner diameter of the air-smoke mixing central pipe 8 is controlled within the range of 1.5-3, and can be selected from 1.8, 2, 2.3, 2.5, 2.7 and the like.

In the embodiment, the ratio of the distance between the inlet end face and the outlet end face of the bell mouth 11 to the inner diameter of the air-smoke mixing central tube 8 is controlled within the range of 0.8-1.2, and can be selected as 0.9, 1, 1.1 and the like.

The high-speed air jet pipes 9 in the embodiment can be one jet pipe or a group of jet pipes; the outlet end of the air high-speed spray pipe 9 extends into the bell mouth, and the range of the ratio of the distance between the outlet end face of the air high-speed spray pipe 9 and the inlet end face of the bell mouth 11 to the inner diameter of the air-smoke mixing central pipe 8 is controlled between 0.5 and 1.4, preferably 0.6, 0.8, 1, 1.2 and the like.

The flow area of the smoke backflow inlet 12 in the embodiment is not smaller than the flow cross-sectional area of the air-smoke mixing central pipe 8; the position of the smoke backflow inlet 12 is between the end face of the outlet of the high-speed air spraying pipe 9 and the end face of the outlet of the air collection chamber 7, so that air is prevented from flowing out of the smoke backflow inlet 12 and mixing into smoke outside the mixing pipe 8.

The end surface of the air collection chamber 7 in the embodiment, which is in contact with the flue gas, is in a shape (not limited to an ellipsoid) which can effectively reduce the loss of the flow resistance of the flue gas, and the end surface of the outlet of the air collection chamber 7 is in a shape (not limited to a cone) which can effectively reduce the loss of the flow resistance of the air therein.

With reference to fig. 5, a set of flue gas turbulence baffle 13 is disposed on the air tube bundle 6 and the heat insulation sleeve 10 in the flue gas flowing direction in the embodiment, the flue gas turbulence baffle is fixed on the heat insulation sleeve 10 and alternately distributed according to the notch direction set thereon, if the heat exchange efficiency is increased, the distance between the flue gas turbulence baffles can be reduced, the number of the flue gas turbulence baffles is increased, thereby increasing the flue gas flowing length, the notch 131 on the flue gas turbulence baffle 13 is alternately distributed in parallel, and the air tube bundle 6 and the heat insulation sleeve 10 run through the flue gas turbulence baffle 13.

Referring to fig. 6 (not limited to the arrangement mode in fig. 5), in order to further increase the heat exchange area, the number of the air tube bundles 6 can be increased, and the openings on the flue gas turbulence baffle 13 are also adjusted correspondingly according to the arrangement mode of the air tube bundles 6.

Referring to fig. 7, in order to further increase the heat exchange area, a spiral tube bundle or other special-shaped tube bundles which can be distributed in an annular space can be used instead of the straight tube bundle under the condition of the same number of the air tube bundles 6.

Referring to fig. 8, to enhance heat exchange within air tube bundle 6, inserts of different cross-sectional shapes may be added, the cross-sectional shapes of which are not limited to in-line, cross, or in-line spiral.

The working principle of the embodiment is as follows:

referring to fig. 3 and 4, cold air enters the air distribution chamber 5 from the air inlet 2, flows into the air tube bundle 6 from the air distribution chamber 5, and starts to perform cross-flow heat exchange with flue gas flowing around the air tube bundle 6, the preheated air is converged into the air collection chamber 7 from the air tube bundle 6, then flows through the air high-speed nozzle 9 at the outlet of the air collection chamber 7 and is sprayed into the air-flue gas mixing central tube 8, a negative pressure area is formed around the high-speed air flow due to the high-speed spraying of the air flow, high-temperature flue gas with a certain proportion is sucked from the flue gas backflow inlet 12, the preheated air and the high-temperature flue gas are subjected to heat-mass exchange in the air-flue gas mixing central tube 8, and after flowing and mixing for a certain distance, the fully mixed air and flue gas flow out of the preheater from the preheated mixed combustion-supporting gas outlet 3 and flow. Because the flue gas is mixed, the oxygen concentration of the combustion-supporting gas is reduced, and the burner can realize flameless combustion in the radiant tube under the condition of lower temperature in the radiant tube, thereby greatly reducing NO_XThe temperature uniformity of the wall surface of the radiant tube is improved while the exhaust is carried out. A part of high-temperature flue gas in the radiant tube enters an air-flue gas mixing central tube 8 for circulation before entering a preheater due to the negative pressure entrainment effect; the other part of high-temperature flue gas passes through the air tube bundle 6 in the cross flow direction to exchange heat under the action of the flue gas turbulence baffle 13, and finally is discharged out of the preheater through the smoke discharge outlet 4. The amount of smoke which participates in air preheating through the preheater is lower than that of smoke flowing back at the outlet of the preheater, high-temperature smoke is injected at the inlet of the preheater under the condition that the air amount is unchanged, and lower smoke exhaust temperature can be achieved while the air preheating temperature is improved, so that the waste heat recovery amount is improved, and the energy is saved by about 10%; because the smoke is injected before entering the preheater, the injected smoke does not have the total flow resistance of the preheater, so that the negative pressure of the air required by the injected smoke is reduced compared with the injection at the outlet of the preheater, the pressure required by the air inlet is reduced, in other words, higher smoke circulation rate can be realized under the same air inlet pressure.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it is obvious that those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The utility model provides a high-efficient pre-heater that cooperation radiant tube nozzle used, including cold air entry (2) of setting on casing (1), preheat mixed combustion-supporting gas export (3) and outlet of discharging fume (4), a serial communication port, still including setting up air distributor box (5) in the casing, air tube bank (6), air collection chamber (7) and empty cigarette mixed center tube (8), the air distributor box links to each other with cold air entry, air tube bank both ends link to each other with air collection chamber and air distributor box respectively, empty cigarette mixed center tube one end links to each other with preheating mixed combustion-supporting gas export, the other end is stretched into the intercommunication by air high-speed spray tube (9) of air collection chamber and is formed with annular flue gas reflux inlet (12) with the outer wall, empty cigarette mixed center tube is equipped with heat insulating sleeve (10) outward, heat insulating sleeve one end is blocked by the air distributor box, leave annular between the other end and the air high-speed spray tube outer wall and be formed A bell mouth (11) with a tapered conical surface along the flowing direction of the flue gas.

2. A high efficiency preheater according to claim 1, wherein the air distribution chamber has an interior space topologically equivalent to a ring shape with an inlet connected to the cold air inlet and a plurality of outlets connected to the air tube bundle; the spatial shape of the inner cavity of the air collection chamber is topologically equivalent to a column shape, and the air collection chamber is provided with a plurality of inlets connected with the air pipe bundle and more than one outlet connected with the air high-speed nozzle; the number of the corresponding air high-speed spray pipes is more than one.

3. A high efficiency preheater according to claim 1 or claim 2, wherein said air distribution chamber and air collection chamber are connected by one or more air tube bundles having a tube structure including but not limited to a straight tube bundle or a spiral tube bundle.

4. A high efficiency preheater as recited in claim 3, wherein said air tube bundle tubes are provided with heat exchange enhancing inserts within said tubes, said inserts having cross-sections including but not limited to a straight, cross or straight spiral.

5. A high efficiency preheater according to claim 1, wherein the opposite end surface of the air collection chamber facing the flue gas inlet is provided with a convex surface for reducing the flow resistance of the flue gas, the convex surface including but not limited to a spherical surface or an ellipsoidal surface; the outlet end face of the air collection chamber is provided with a flow guide surface for reducing the air flow resistance in the air chamber, and the flow guide surface comprises but is not limited to a conical surface.

6. A high-efficiency preheater matched with a radiant tube burner for use according to claim 1, wherein an air heat insulation interlayer is formed between the tube wall of the heat insulation sleeve and the tube wall of the air-smoke mixing central tube, and the ratio of the outer diameter of the heat insulation sleeve to the inner diameter of the air-smoke mixing central tube ranges from 1.5 to 3.

7. A high-efficiency preheater matched with a radiant tube burner for use according to claim 1, wherein the ratio of the distance between the inlet end face and the outlet end face of the bell mouth to the inner diameter of the air-smoke mixing central tube ranges from 0.8 to 1.2.

8. A high-efficiency preheater matched with a radiant tube burner for use according to claim 1, wherein the outlet end of the air high-speed spray pipe extends into the bell mouth, and the ratio of the distance between the outlet end face of the air high-speed spray pipe and the inlet end face of the bell mouth to the inner diameter of the air-smoke mixing central pipe is in the range of 0.5-1.4.

9. A high-efficiency preheater used in cooperation with a radiant tube burner as claimed in claim 1, wherein the position of the flue gas backflow inlet is located between the outlet end face of the air high-speed spray pipe and the outlet end face of the air collection chamber, and the flow area of the flue gas backflow inlet is not smaller than the flow cross-sectional area of the air-smoke mixing central pipe.

10. A preheater as claimed in claim 1, wherein the air tube bundle and the heat shield are provided with gaps and flue gas baffle plates (13) disposed in parallel and alternately at intervals, and the air tube bundle and the heat shield penetrate the flue gas baffle plates.