An efficient flue gas cooler

Abstract

The present invention discloses an efficient flue gas cooler, which includes a flue gas inlet, a flue gas outlet, and a heat exchange module disposed between the flue gas inlet and the flue gas outlet. The heat exchange module includes several rows of tube rows composed of high specific surface area efficient tubes. The axis of the high specific surface area efficient tubes is perpendicular to the flue gas flow direction. Air flows inside the high specific surface area efficient tubes, and flue gas flows in the space composed of tube sheets, side plates, and the outer surface of the high specific surface area efficient tubes. The efficient flue gas cooler of the present invention adopts modular and standardized design and production, and can be flexibly assembled according to actual needs, shortening the manufacturing, supply, and installation time and reducing costs. The high specific surface area efficient tubes have high heat exchange efficiency; the tube rows have good anti-vibration performance, the flue gas flow field is uniform, and it is not easy to accumulate ash; the special tube layout form at the flue gas side inlet and outlet, and different tube pitches are adopted for the tube bundle, reducing the flow velocity difference in different regions.

Description

Technical Field

[0001] The present invention relates to an efficient flue gas cooler, which is mainly applied to the production system of glass furnaces. Background Art

[0002] In traditional technologies, the flue gas of glass furnaces has a relatively high dust content, and contains dust with relatively high hardness such as silicon dioxide, has a relatively high alkali content, strong adhesiveness, and is not easy to clean ash.

[0003] With the increasingly high national environmental protection requirements, original polluting enterprises need to carry out technological upgrades again, and severely rectify enterprises with serious pollution processes. Glass furnace enterprises are highly polluting enterprises. The current exhaust gas temperature of glass furnaces is too high, and there is no dust removal, denitrification, and desulfurization. In order to meet the national environmental protection requirements, it is necessary to carry out dust removal, denitrification, and desulfurization treatments on the flue gas with too high exhaust gas temperature. However, the flue gas coming out of the glass furnace is as high as 600 °C, which cannot meet the process requirements of dust removal, high-temperature denitrification, and desulfurization. Therefore, it is necessary to use an efficient heat exchanger to reduce the flue gas temperature.

[0004] At present, most existing air preheaters generally use smooth tubes or corrugated tubes as their heat exchange elements, and carry out heat exchange by the flue gas flowing across their tube bundles. Since smooth tubes do not have enhanced heat transfer, the heat transfer efficiency is extremely low, and the heat transfer coefficient is generally 15 - 20 W / (m²·°C), resulting in a sharp increase in the weight and volume of the air preheater. The heat transfer coefficient of corrugated tubes is increased compared with that of smooth tubes, and there is a certain strengthening effect, but the effect is not obvious. Instead, the resistance inside and outside the tubes brought by the corrugations increases, and it is also easy to scale and corrode severely. In order to solve the problems of the large weight and volume, large resistance, easy scaling and corrosion of conventional air preheaters or flue gas coolers, which lead to the problem of the relatively tight on-site conditions, it is urgent to introduce an efficient heat exchange tube for the current gas-gas heat exchanger problems.

[0005] Content of the Invention Patent

[0006] The purpose of the present invention is to provide an efficient flue gas cooler to solve the problem of limited installation space in the glass furnace system, solve the resistance, reduce wear and ash blockage, extend the equipment life, and at the same time reduce the exhaust gas temperature to meet the process requirements of environmental protection upgrade and transformation, and avoid the problem of the flue gas cooler failing due to ash blockage, wear, and low heat transfer efficiency.

[0007] To achieve the above purposes, the present invention proposes the following technical solutions:

[0008] An efficient flue gas cooler includes a flue gas inlet, a flue gas outlet, and at least one heat exchange module disposed between the flue gas inlet and the flue gas outlet. The heat exchange module includes a cubic frame. Inside the cubic frame, there are several rows of tube rows composed of high-specific-surface efficient tubes. The axial direction of the high-specific-surface efficient tubes is perpendicular to the flue gas flow direction. Tube plates are provided on the frame end faces perpendicular to the axial direction of the high-specific-surface efficient tubes. Side plates are provided at the top and bottom of the frame. Air flows inside the high-specific-surface efficient tubes, and flue gas flows in the space composed of the tube plates, side plates, and the outer surfaces of the high-specific-surface efficient tubes.

[0009] The high-specific-surface efficient tubes are of a spiral structure.

[0010] The spacing between tube rows is greater than the maximum outer diameter of the high-specific-surface efficient tubes.

[0011] The spacing between tubes in the tube row is equal to the maximum outer diameter of the high-specific-surface efficient tubes. The tubes are in contact through bumps, and the bumps are fixed by welding to form an integral tube row.

[0012] Wear-resistant tiles are provided on the outside of the high-specific-surface efficient tubes closest to the flue gas inlet in each tube row.

[0013] Along the flue gas flow direction, the tube row density inside the frame gradually increases.

[0014] Using high-specific-surface efficient tubes as the heat exchange elements for the heat exchange surface of the low-temperature economizer solves the problems of small heat transfer coefficient of the flue gas cooler, saving the heat exchange area and space of the heat exchanger. Adopting an advanced tube layout method reduces resistance, prevents fouling on the heat exchange surface of the cooler, resulting in ash accumulation, and realizes the design concept of three-dimensional variable space, making the flow field

[0015] The high-specific-surface efficient tubes are in "bump" contact with each other, without the need for an external support structure. The tubes are spot-welded to form an integral body, improving the stiffness of the tube sheets. In this way, the tubes support each other, and even when the flow velocity of the fluid outside the tubes is very high, there will be no vibration impact on the heat exchange tube bundle.

[0016] When the fluid flows inside or outside the tubes, due to the influence of the special spiral structure inside the high-specific-surface tubes, the thermal boundary layer is destroyed, making the thermal boundary layer thinner and strengthening the heat exchange between the hot and cold fluids. And it increases the effective heat transfer distance between the fluids inside and outside the tubes. Because the fluid in the central part of the ordinary round tube basically does not participate in heat exchange, the heat exchange efficiency is low. The three-dimensional efficient tubes precisely shorten the effective heat transfer distance between the inside and outside of the tubes through optimized deformation, improving the heat transfer efficiency.

[0017] Since the inlet of the flue gas cooler is the high-temperature end, the volumetric flow rate is very large, which causes a very large impact on the heat exchange tubes, exacerbates wear, increases resistance. Therefore, a flexible "diversion" type tube layout is adopted at the inlet end of the heat exchange tubes, increasing the flow area, guiding the flue gas to enter the heat exchange tube bundle smoothly and comfortably, reducing the resistance loss caused by eddy currents, and increasing the tube spacing of the heat exchange tubes to reduce the flue gas flow velocity to a reasonable range. At the outlet end of the flue gas cooler, the volumetric flow rate of the flue gas becomes smaller. Appropriately increase the density of the heat exchange tubes, reduce the flow area, and increase the flue gas flow velocity to a reasonable range. By adopting different tube layouts for the inlet and outlet of the tube flue gas cooler and the intermediate tube bundle, the gap between the inlet and outlet flow areas is increased, thereby reducing the flow velocity gap, making the flow velocity of the entire heat exchange tube bundle relatively uniform, and optimizing the flow field.

[0018] The tube bundle of the flue gas cooler is arranged in tube rows, that is, the tube bundle is composed of tube rows, and the row spacing between tube rows is greater than the maximum outer diameter of the high specific surface area high-efficiency tube, aiming to reduce the flow velocity outside the tubes and reduce the resistance loss of the tube bundle. The spacing between tubes in the tube row is equal to the maximum outer diameter of the high specific surface area high-efficiency tube, that is, the tubes are in contact with each other and support each other, and the contact points between the tubes in the tube row are fixed by welding to form a whole, aiming to increase the rigidity of the tube row, eliminate the possibility of vibration of the flue gas cooler, reduce the formation of eddy currents, reduce the resistance loss outside the tubes, slow down the wear of the heat exchange tubes, and extend the service life of the flue gas cooler.

[0019] The flue gas cooler adopts modular and standardized design and production, and can be flexibly assembled according to actual needs, shortening the manufacturing, supply and installation time and reducing costs.

[0020] The beneficial effects of the present invention are as follows:

[0021] First, the heat exchange efficiency of the heat exchange element is high;

[0022] Second, it has good anti-vibration performance and small volume;

[0023] Third, the flue gas flow field is very uniform and not prone to ash accumulation;

[0024] Fourth, the special tube layout form at the inlet and outlet of the flue gas side, and different tube spacings are adopted for the tube bundle, reducing the flow velocity gap in different areas of the tube bundle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the high-efficiency flue gas cooler of the present invention;

[0026] Figure 2 is the front view of the heat exchange module;

[0027] Figure 3 is the front view of the heat exchange module;

[0028] Figure 4It is a top view of the heat exchange module;

[0029] Figure 5 It is Figure 4 Partial enlarged view B of the middle tube row

[0030] Figure 6 It is a sectional view of the tube row;

[0031] Figure 7 It is Figure 3 Partial enlarged view A of the inlet tube layout of

[0032] Figure 8 It is the tube layout diagram of the tube bundle.

[0033] Explanation of reference numerals: 1. Heat exchange module; 2. Frame; 3. Positioning pin; 4. Lifting lug; 5. High specific surface area high-efficiency tube; 6. Side plate; 7. Tube sheet; 8. Welding point; 9. Abrasion-resistant tile. Specific implementation mode

[0034] The content of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes.

[0035] As Figure 1 shown, a high-efficiency flue gas cooler is composed of two upper and lower heat exchange modules 1, a trumpet-shaped flue gas inlet and a flue gas outlet. The flue gas flows outside the high specific surface area high-efficiency tubes, and the air flows inside the high specific surface area high-efficiency tubes. The flue gas flows along the gap between the tube rows and exchanges heat with the air flowing inside the tubes in a cross-flow heat exchange mode. The heat exchange modules of the flue gas cooler can be freely combined, either in parallel or in series.

[0036] As Figures 2 - 4 shown, it is one of the heat exchange modules of the flue gas cooler. The heat exchange module is composed of components such as an inlet frame 2, a positioning pin 3, a lifting lug 4, a high specific surface area high-efficiency tube 5, a side plate 6, a tube sheet 7, etc. The outer shape of the module is a regular cube. The flue gas enters from the inlet along the thickness direction of the module and flows along the gap between the heat exchange tube rows composed of the high-efficiency tubes 5. The flue gas flow channel formed by the tube rows enables the flue gas to flow smoothly, reduces the resistance loss of the flue gas flow, and at the same time reduces the abrasion of the high-dust flue gas on the high-efficiency tube 5. Since there are relatively few formed channel dead ends and the outer surface of the heat exchange element is relatively smooth, the dust accumulation is also relatively small. The heated medium - air flows along the inner side (inside the tube) of the high specific surface area high-efficiency tube 5 and forms a cross-flow shell-and-tube heat exchange with the flue gas. The tube sheet 7 and the high specific surface area high-efficiency tube 5 play a sealing role, effectively preventing the mutual leakage of the two medium fluids, that is, preventing the phenomenon of air leaking to the flue gas side and achieving absolute sealing. The side plate 6 prevents the outdoor air from flowing into the flue gas side of the module 2. Due to the high heat exchange efficiency of the heat exchange element, the consumption of materials of the module is greatly reduced, the structure is compact, and the volume is small.

[0037] AsFigures 5 - 6 As shown, it is Figure 2 a partially enlarged view of the tube bank. It describes the fixation of the high specific surface area efficient tubes 5 between the tube banks. Each cross-section perpendicular to the axial direction of each high specific surface area efficient tube 5 has a maximum bump. The bumps between the heat exchange tubes can contact each other, and these contacted bumps are spot-welded. This connection point is the welding point 8. After connecting the two ends of the heat exchange tubes to the tube sheet 7, the heat exchange tubes in contact with each other on the same plane are spot-welded and solidified together to form a tube bank component with extremely high strength, preventing vibration.

[0038] In addition, when the flue gas flows through the channels between the tube banks, there are also micro-channels n between the tubes of the tube bank, forming mutual mixing and cross-flow between the tube banks, further destroying the boundary layer of the fluid outside the tubes, achieving enhanced heat transfer of the fluid outside the tubes, and at the same time making the heat exchange tube bundle have no eddy current and dead angle, and is not easy to accumulate ash.

[0039] As Figure 7 shown, a partially enlarged view A of the tube layout on the tube sheet at the inlet end of the module. At the inlet end, the method of reducing the number of tube layouts is adopted, and a flexible "diversion" type tube layout is used to increase the flow area, guide the flue gas to enter the heat exchange tube bundle more smoothly and comfortably, reduce the resistance loss caused by eddy current, and increase the tube pitch of the heat exchange tubes to reduce the flue gas flow rate to a reasonable range. An anti-abrasion tile 9 is arranged on the first row of tubes perpendicular to the flue gas flow direction to reduce the damage degree of the first row of tubes with the largest impact and wear amount.

[0040] As Figure 8 shown, since the volume flow rate of the flue gas continuously shrinks as it cools, in order to make the flue gas flow rate in the module tend to be consistent, the density of the heat exchange tubes in different regions of the module must be different. As shown in regions 1 and 2 in the figure, the longitudinal tube pitch S of the two regions is equal, while the transverse tube pitch δ1 ≥ δ2. So that the flow areas of the two regions are 1 region ≥ 2 region, and thus the flow velocities tend to be consistent, reducing the resistance loss caused by the change in flow velocity.

[0041] The above detailed description is a specific description of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention should be included in the patent scope of this case.

Claims

1. An efficient flue gas cooler, characterized in that: It includes a flue gas inlet, a flue gas outlet, and at least one heat exchange module disposed between the flue gas inlet and the flue gas outlet. The heat exchange module includes a cubic frame. A number of tube rows composed of high specific surface efficient tubes are arranged inside the cubic frame. The axial direction of the high specific surface efficient tubes is perpendicular to the flue gas flow direction. Tube plates are arranged on the frame end faces perpendicular to the axial direction of the high specific surface efficient tubes. Side plates are arranged at the top and bottom of the frame. Air flows inside the high specific surface efficient tubes, and flue gas flows in the space composed of the tube plates, the side plates, and the outer surfaces of the high specific surface efficient tubes; along the flue gas flow direction, the tube row density inside the frame gradually increases; the high specific surface efficient tubes are of a spiral structure; wear-resistant tiles are arranged on the outside of the high specific surface efficient tubes closest to the flue gas inlet in each tube row.

2. The high-efficiency flue gas cooler according to claim 1, wherein: The spacing between the tube rows is greater than the maximum outer diameter of the high specific surface efficient tubes.

3. The high-efficiency flue gas cooler according to claim 1, wherein: The spacing between the tubes in the tube row is equal to the maximum outer diameter of the high specific surface efficient tubes. The tubes are in contact through bumps, and the bumps are fixed by welding to form an integral tube row.

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