Industrial boiler SCR reactor outlet waste heat recovery heat exchanger

Abstract

An industrial boiler SCR reactor outlet waste heat recovery heat exchanger comprises a water outlet header and a water inlet header. A high-temperature section double-H fin type heat exchange tube group, a middle-temperature section light tube type heat exchange tube group, a middle header and a low-temperature section light tube type heat exchange tube group are sequentially communicated between the water outlet header and the water inlet header; the water outlet header is installed at the topmost end of the heat exchanger, and the water inlet header is installed at the bottommost end of the heat exchanger. The interior of the heat exchanger is sequentially divided into a high-temperature flue gas area, a medium-temperature flue gas area and a low-temperature flue gas area from top to bottom. The high-temperature section double-H fin type heat exchange tube set is arranged in a high-temperature flue gas area, the medium-temperature section light tube type heat exchange tube set is arranged in a medium-temperature flue gas area, and the low-temperature section light tube type heat exchange tube set is arranged in a low-temperature flue gas area. A middle header is arranged at an outlet of the low-temperature section light pipe type heat exchange pipe set. The heat exchanger has the advantages of being moderate in size, convenient to overhaul and deash structurally, and convenient to overhaul and replace a low-temperature section corroded and damaged pipeline.

Description

Technical Field

[0001] This utility model relates to the field of industrial boiler flue gas denitrification technology, specifically to a waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor. Background Technology

[0002] The existing SCR reactor outlet waste heat recovery heat exchanger technology has the following problems:

[0003] Existing all-smooth tube heat exchangers lack enhanced heat transfer capabilities, have a large number of tube rows, are bulky, and occupy a lot of space. They are difficult to arrange due to limited outlet space for industrial boiler SCR reactors. They also consume a lot of steel, have high costs, lack an inlet water mixing and temperature control system, and are prone to ash accumulation and corrosion in the low-temperature section.

[0004] After ash accumulation and corrosion in the low-temperature section, cleaning and maintenance become difficult. This can lead to leaks in individual heat exchange tubes. Emergency repairs require blindly plugging an entire row of heat exchange tubes, resulting in significant heat exchange area loss and making replacement of damaged pipes difficult.

[0005] Existing all-fin heat exchangers lack inlet water mixing and temperature control systems. Due to their finned heat exchange structure, they are prone to dust accumulation and corrosion in the low-temperature section.

[0006] After ash accumulation and corrosion in the low-temperature section, cleaning and maintenance become difficult. This can lead to leaks in individual heat exchange tubes. Emergency repairs require blindly plugging an entire row of heat exchange tubes, resulting in significant heat exchange area loss and making replacement of damaged pipes difficult. Utility Model Content

[0007] In order to overcome the defects of the existing technology, this utility model proposes a waste heat recovery heat exchanger for the outlet of an industrial boiler SCR reactor. The heat exchanger has the characteristics of moderate heat exchanger size, easy structure for maintenance and ash removal, and convenient maintenance and replacement of corrosion-damaged pipes in the low-temperature section.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0009] An industrial boiler SCR reactor outlet waste heat recovery heat exchanger includes an outlet water header 1 and an inlet water header 6; the outlet water header 1 and the inlet water header 6 are connected in sequence to a high temperature section double H fin heat exchange tube group 2, a medium temperature section bare tube heat exchange tube group 3, an intermediate header 4, and a low temperature section bare tube heat exchange tube group 5.

[0010] The outlet water header 1 is installed at the top of the heat exchanger, and the inlet water header 6 is installed at the bottom of the heat exchanger.

[0011] The heat exchanger is divided into three zones from top to bottom: a high-temperature flue gas zone, a medium-temperature flue gas zone, and a low-temperature flue gas zone.

[0012] The high-temperature section double H-fin heat exchanger tube group 2 is located in the high-temperature flue gas region, the medium-temperature section bare tube heat exchanger tube group 3 is located in the medium-temperature flue gas region, and the low-temperature section bare tube heat exchanger tube group 5 is located in the low-temperature flue gas region; an intermediate header 4 is installed at the outlet of the low-temperature section bare tube heat exchanger tube group 5.

[0013] The high-temperature section double H-fin heat exchanger tube group 2 is double H-fin type, the medium-temperature section bare tube heat exchanger tube group 3 is bare tube type, and the low-temperature section bare tube heat exchanger tube group 5 is bare tube type, together forming a rectangular heat exchanger.

[0014] Compared with the all-smooth tube heat exchanger assembly, the high-temperature section double H-fin heat exchanger assembly 2, the medium-temperature section bare tube heat exchanger assembly 3, and the low-temperature section bare tube heat exchanger assembly 5 have reduced volume and steel consumption.

[0015] The medium-temperature section bare tube heat exchanger assembly 3 is equipped with 25 layers of bare tube heat exchangers according to actual needs, and a dust removal and maintenance door 7 is provided on the longer side of the bare tube heat exchanger.

[0016] The low-temperature section bare tube heat exchanger assembly 5 is equipped with 5 layers of bare tube heat exchanger tubes according to actual needs. The bottom (inlet) of the bare tube heat exchanger assembly 5 is equipped with a water inlet header 6, and the top (outlet) is equipped with an intermediate header 4.

[0017] Inspection and cleaning manholes 8 are provided on the flue wall of the inspection and cleaning space between the high-temperature section double H finned heat exchanger tube group 2 and the medium-temperature section bare tube heat exchanger tube group 3. Inspection and cleaning manholes 8 are provided on the heat exchanger wall along the flue gas flow direction between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5.

[0018] Maintenance space is provided between the high-temperature section double H finned heat exchanger tube group 2 and the medium-temperature section bare tube heat exchanger tube group 3, and between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5. At the same time, an intermediate header 4 is set between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5 to facilitate inspection, cleaning and replacement of corroded and leaking heat exchanger tubes. If a single heat exchanger tube leaks, only one blind tube needs to be blinded.

[0019] The beneficial effects of this utility model are:

[0020] The shape and structure of this utility model make the heat exchanger of moderate size, easy to inspect and clean, and convenient to repair and replace corrosion-damaged pipes in the low-temperature section.

[0021] The high-temperature section double H-fin heat exchanger tube assembly, the medium-temperature section bare tube heat exchanger tube assembly, and the low-temperature section bare tube heat exchanger tube assembly have reduced volume and lower steel consumption.

[0022] With the addition of an intermediate header, this utility model only requires replacing the heat exchange tubes between the inlet header and the intermediate header in case of leakage, thus avoiding the impact on the medium-temperature and high-temperature heat exchange tubes between the intermediate header and the outlet header. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] like Figure 1 As shown, an industrial boiler SCR reactor outlet waste heat recovery heat exchanger includes an outlet water header 1 and an inlet water header 6; the outlet water header 1 and the inlet water header 6 are connected in sequence to a high temperature section double H fin heat exchange tube group 2, a medium temperature section bare tube heat exchange tube group 3, an intermediate header 4, and a low temperature section bare tube heat exchange tube group 5.

[0026] The outlet water header 1 is installed at the top of the heat exchanger, and the inlet water header 6 is installed at the bottom of the heat exchanger.

[0027] The heat exchanger is divided into three zones from top to bottom: a high-temperature flue gas zone, a medium-temperature flue gas zone, and a low-temperature flue gas zone.

[0028] The high-temperature section double H-fin heat exchanger tube group 2 is located in the high-temperature flue gas region, the medium-temperature section bare tube heat exchanger tube group 3 is located in the medium-temperature flue gas region, and the low-temperature section bare tube heat exchanger tube group 5 is located in the low-temperature flue gas region; an intermediate header 4 is installed at the outlet of the low-temperature section bare tube heat exchanger tube group 5.

[0029] The high-temperature section double H-fin heat exchanger tube group 2 is double H-fin type, the medium-temperature section bare tube heat exchanger tube group 3 is bare tube type, and the low-temperature section bare tube heat exchanger tube group 5 is bare tube type, together forming a rectangular heat exchanger.

[0030] Compared with the all-smooth tube heat exchanger assembly, the high-temperature section double H-fin heat exchanger assembly 2, the medium-temperature section bare tube heat exchanger assembly 3, and the low-temperature section bare tube heat exchanger assembly 5 have reduced volume and steel consumption.

[0031] The widest side panel of the medium-temperature section bare tube heat exchanger assembly 3 is provided with a dust removal and maintenance door 7.

[0032] The low-temperature section bare tube heat exchanger assembly 5 is provided with 5 layers of bare tube heat exchanger assembly 5. The bottom inlet of the bare tube heat exchanger assembly 5 is provided with a water inlet header 6, and the upper outlet is provided with an intermediate header 4.

[0033] Inspection and cleaning manholes 8 are provided on the flue wall of the inspection and cleaning space between the high-temperature section double H finned heat exchanger tube group 2 and the medium-temperature section bare tube heat exchanger tube group 3. Inspection and cleaning manholes 8 are provided on the heat exchanger wall along the flue gas flow direction between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5.

[0034] Maintenance space is provided between the high-temperature section double H finned heat exchanger tube group 2 and the medium-temperature section bare tube heat exchanger tube group 3, and between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5. At the same time, an intermediate header is set between the medium-temperature section bare tube heat exchanger tube group 3 and the low-temperature section bare tube heat exchanger tube group 5 to facilitate inspection, cleaning and replacement of corroded and leaking heat exchanger tubes. If a single heat exchanger tube leaks, only the leaking heat exchanger tube needs to be blinded, avoiding short circuit of the entire heat exchanger tube row due to leakage of a single heat exchanger tube, which would cause a large loss of heat exchanger heat exchange area.

[0035] The working principle of this utility model:

[0036] The boiler return water enters from the heat exchanger inlet header 6 and flows from bottom to top inside the heat exchanger tubes. It passes through the low-temperature section bare tube heat exchanger tube assembly 5 and is collected in the intermediate header 4. Then it enters the medium-temperature section bare tube heat exchanger tube assembly 3 and then the high-temperature section double H fin heat exchanger tube assembly 2. After being collected in the outlet header 1, it goes to the boiler inlet. The boiler flue gas flows from top to bottom outside the heat exchanger tubes. The heat of the flue gas is transferred to the water flowing from bottom to top inside the heat exchanger tubes under the action of convection heat transfer. The water temperature increases along the water flow direction, while the flue gas temperature decreases along the flue gas flow direction.

[0037] The top of the heat exchanger is connected to the outlet of the SCR denitrification reactor, where the flue gas temperature is approximately 320℃~350℃. The bottom is connected to the inlet of the bag filter, where the flue gas is cooled by heat absorption through the heat exchanger, resulting in a flue gas temperature of approximately 120℃~150℃.

[0038] In the high-temperature section, the water temperature inside the double H-fin heat exchanger tube group is above 65℃, and the flue gas temperature outside the tubes is the highest at 320℃~350℃ in all sections of the economizer. The tube wall temperature is the highest, far above the flue gas acid dew point and water dew point, and also above the ammonium bisulfate decomposition temperature of 290℃. The flue gas velocity is the highest, and ash can be carried away by the flue gas. Although there is a double H-fin structure to enhance convective heat transfer, it is not easy to accumulate ash or corrode.

[0039] The medium-temperature section heat exchanger tube group 3, where the flue gas temperature is between 150℃ and 290℃, is prone to the formation of viscous ammonium bisulfate, and the low-temperature section heat exchanger tube group 5, where the flue gas temperature is between 120℃ and 150℃, is prone to acid and water condensation on the tube walls, and is also prone to ash accumulation and corrosion. Both sections utilize a bare tube structure that is less prone to ash accumulation and easier to clean. An intermediate header 4 is installed between the low-temperature section heat exchanger tube group 5 (where the flue gas temperature is between 120℃ and 150℃) and the medium-temperature section bare tube heat exchanger tube group 3 to isolate the low-temperature section tube group from the medium and high-temperature section tube groups. High-temperature heat exchange tubes are prone to corrosion and leakage. With the addition of an intermediate header, only the heat exchange tubes between the inlet header and the intermediate header need to be replaced when leakage occurs. This avoids affecting the medium-temperature and high-temperature heat exchange tubes between the intermediate header and the outlet header. Moreover, there is maintenance space between the medium-temperature bare tube heat exchange tube group 3 and the low-temperature bare tube heat exchange tube group 5, which facilitates inspection, cleaning, and replacement of corroded and leaking heat exchange tubes. If a single heat exchange tube leaks, only one blind tube needs to be blinded, avoiding short-circuiting the entire heat exchange tube row due to a single heat exchange tube leak, which would cause significant loss of the heat exchanger's heat exchange area.

[0040] The cleaning and maintenance door 7 on the widest side panel of the medium-temperature section bare tube heat exchanger tube assembly 3 facilitates the cleaning and maintenance of the medium-temperature section bare tube heat exchanger tube assembly during boiler shutdown maintenance. The cleaning and observation manhole 8 facilitates the observation of ash accumulation and corrosion of the heat exchanger during operation and maintenance, and the inspection and cleaning of the heat exchanger during boiler shutdown maintenance.

Claims

1. A waste heat recovery heat exchanger for the outlet of an industrial boiler SCR reactor, characterized in that, It includes an outlet water header (1) and an inlet water header (6); the outlet water header (1) and the inlet water header (6) are connected in sequence to a high-temperature section double H fin heat exchange tube group (2), a medium-temperature section bare tube heat exchange tube group (3), an intermediate header (4), and a low-temperature section bare tube heat exchange tube group (5). The outlet water header (1) is installed at the top of the heat exchanger, and the inlet water header (6) is installed at the bottom of the heat exchanger. The heat exchanger is divided into three zones from top to bottom: a high-temperature flue gas zone, a medium-temperature flue gas zone, and a low-temperature flue gas zone. The high-temperature section double H fin heat exchange tube group (2) is set in the high-temperature flue gas area, the medium-temperature section bare tube heat exchange tube group (3) is set in the medium-temperature flue gas area, and the low-temperature section bare tube heat exchange tube group (5) is set in the low-temperature flue gas area; an intermediate header (4) is set at the outlet of the low-temperature section bare tube heat exchange tube group (5).

2. The waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor according to claim 1, characterized in that, The high-temperature section double H fin heat exchanger tube group (2) is double H fin type, the medium-temperature section bare tube heat exchanger tube group (3) is bare tube type, and the low-temperature section bare tube heat exchanger tube group (5) is bare tube type, together forming a rectangular heat exchanger.

3. The waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor according to claim 1, characterized in that, The medium-temperature section bare tube heat exchanger assembly (3) is equipped with bare tube heat exchangers, and a dust removal and maintenance door (7) is provided on the longer side of the bare tube heat exchanger.

4. The waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor according to claim 1, characterized in that, The low-temperature section bare tube heat exchanger assembly (5) is equipped with bare tube heat exchanger tubes. The bottom of the bare tube heat exchanger assembly (5) is equipped with a water inlet header (6) and the top is equipped with an intermediate header (4).

5. The waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor according to claim 1, characterized in that, Inspection and cleaning manholes (8) are provided on the flue wall of the inspection and cleaning space between the high-temperature section double H fin heat exchanger tube group (2) and the medium-temperature section bare tube heat exchanger tube group (3). Inspection and cleaning manholes (8) are provided on the heat exchanger wall along the flue gas flow direction between the medium-temperature section bare tube heat exchanger tube group (3) and the low-temperature section bare tube heat exchanger tube group (5).

6. The waste heat recovery heat exchanger at the outlet of an industrial boiler SCR reactor according to claim 1, characterized in that, Maintenance space is provided between the high-temperature section double H finned heat exchange tube group (2) and the medium-temperature section bare tube heat exchange tube group (3), and between the medium-temperature section bare tube heat exchange tube group (3) and the low-temperature section bare tube heat exchange tube group (5). At the same time, an intermediate header (4) is provided between the medium-temperature section bare tube heat exchange tube group (3) and the low-temperature section bare tube heat exchange tube group (5).

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