Modularized waste heat boiler with SCR (Selective Catalytic Reduction) flue

Abstract

A modularized waste heat boiler with an SCR flue comprises an evaporator module which comprises a plurality of evaporators distributed in parallel and is detachably connected to the side wall of the boiler in an inserted mode. The boiler barrel exchanges heat with the multiple evaporators through a descending pipe and an ascending pipe; and the SCR flue is detachably arranged between the two rear evaporators and is used for carrying out denitration on the flue gas. The device is compact and reasonable in structure and convenient to operate, and all the modules are connected through flues on site. The flue gas high-temperature area adopts a light tube for heat exchange, the flue gas low-temperature area adopts a spiral finned tube for enhancing heat exchange, the heating surface is reasonably arranged, and the SCR flue 6 is arranged for flue gas denitration; the waste heat boiler is compact in structure, modularized in delivery, rapid and convenient to install and capable of reducing the field welding workload, improving the overall quality of the boiler and reducing the content of nitric oxide in smoke.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat boilers, in particular to a modular waste heat boiler with an SCR flue. Background Art

[0002] Waste heat boilers are commonly used devices for energy recovery of industrial high-temperature exhaust gas. They are used in various industrial fields. When recovering high-temperature flue gas, waste heat boilers generally adopt shell or water tube heat exchange structures. When the flow rate of waste heat flue gas is large, it is usually a water tube bulk structure. The volume and weight of water tube bulk boilers will be large, and a large amount of on-site installation work will be required. The cost of the boiler will also be correspondingly high. Moreover, with the improvement of environmental protection requirements, the flue gas emissions of waste heat boilers must also meet the corresponding emission standards. If the nitrogen oxides in the flue gas exceed the standard, denitrification treatment is required. At this time, a waste heat boiler with a compact structure, high heat transfer efficiency, quick and easy installation, and denitrification function is required.

[0003] To this end, we propose a modular waste heat boiler with an SCR flue. Utility Model Content

[0004] In view of the shortcomings of the above-mentioned existing production technology, the applicant provides a modular waste heat boiler with an SCR flue, which is modularized and shipped from the factory, and is quick and convenient to install, which can reduce the workload of on-site welding.

[0005] The technical solution adopted by the utility model is as follows:

[0006] A modular waste heat boiler with an SCR flue, comprising:

[0007] The evaporator module includes a plurality of evaporators arranged in parallel and detachably plugged into the side wall of the boiler to form an evaporation section;

[0008] A boiler drum, which exchanges heat with a plurality of evaporators through downcomers and upcomers;

[0009] The SCR flue is detachably arranged between the two rear evaporators and is used for denitrification of the flue gas.

[0010] Optionally, the evaporator modules are evaporator I, evaporator II and evaporator III in sequence along the flue gas flow direction, and the structure of each evaporator includes:

[0011] Steel frame, which plays a connecting and supporting role;

[0012] There are four upper headers forming a horizontally distributed rectangular structure, and the multiple upper headers are fixed by a steel frame;

[0013] There are four lower headers, which are distributed corresponding to the upper headers, and multiple groups of tube bundles are connected between the upper headers and the lower headers;

[0014] The upper header is connected to the rising pipe joint of the boiler drum through an ascending pipe, and the lower header is connected to the descending pipe joint of the boiler drum through a descending pipe.

[0015] Optionally, the tube bundle of the evaporator I is a plain tube; the tube bundles of the evaporator II and the evaporator III are spiral finned tubes.

[0016] Optionally, a flue gas inlet pipe is arranged on the left side of the evaporator I, a connecting flue is arranged between the modules, a superheater is arranged on the right side of the evaporator II, an SCR flue is arranged between the superheater and the evaporator III, and a flue gas outlet pipe is connected to the right side of the economizer.

[0017] Optionally, it also includes:

[0018] A smoke inlet pipe, which is arranged at the smoke inlet end and is used for smoke to enter;

[0019] A superheater, which is arranged between the evaporator II and the SCR flue, and is used to further heat the flue gas from the saturation temperature to the superheat temperature;

[0020] Connect the flue to install the SCR flue;

[0021] Smoke outlet pipe to facilitate the outflow of smoke;

[0022] The economizer is connected to the flue gas outlet pipe to recover the waste heat of the exhaust gas.

[0023] Optionally, the SCR flue is provided with:

[0024] Spray gun interface, used to connect the spray gun to provide ammonia water;

[0025] The disturbance zone forces the flue gas to be disturbed, so that the flue gas and ammonia water are fully mixed;

[0026] The rectification area changes the smoke from a turbulent state to a uniform and stable state;

[0027] In the reaction zone, under the action of the catalyst, the flue gas undergoes an oxidation-reduction reaction, and NOx reacts to generate N2 and H2O, completing the denitrification function of the flue gas.

[0028] The beneficial effects of the utility model are as follows:

[0029] The utility model has a compact and reasonable structure, is easy to operate, and each module is connected on site by a flue. The utility model adopts light tube heat exchange in the flue gas high temperature zone, and spiral fin tubes are used to enhance heat exchange in the flue gas low temperature zone, reasonably arranges the heating surface, and sets an SCR flue 6 for flue gas denitrification; the waste heat boiler has a compact structure, is modularized and shipped from the factory, is quick and easy to install, can reduce the workload of on-site welding, improve the overall quality of the boiler, and can reduce the nitrogen oxide content in the flue gas.

[0030] The following advantages are also required:

[0031] Each evaporator in the utility model is modularized, and each module is welded and fixed to the connecting flue after being in place, which improves the installation efficiency. The heating surface of each evaporator in the utility model is composed of four groups of headers and tube bundles, and an upper header and a lower header are a group with the tube bundle. The advantage is that a single tube group can be manufactured separately first, and then formed into a whole with other tube groups after ensuring the quality is qualified. The tube bundle 17 of evaporator I3 in the utility model is a light tube; the tube bundle 17 of evaporator II4 and evaporator III7 is a spiral fin tube. Because the temperature of the flue gas contacted by evaporator I3 close to the flue gas inlet direction is higher, the tube sheet of the light tube can meet the heat exchange requirements, and there is no need to increase the contact area additionally. The high-temperature flue gas has lowered its temperature after heat exchange. When the flue gas contacts another subsequent evaporator, the contact area is increased by using spiral fin tube sheets, thereby meeting the heat exchange effect. In this embodiment, the inlet flue gas temperature of the first evaporator is as high as 900℃, which is suitable for light tubes. The inlet flue gas temperature of the second evaporator is 713℃. Finned tubes can be used at this temperature to reduce weight and volume. The third module is a superheater, and the inlet flue gas temperature is 390℃. Because the slightly superheated steam 208 is superheated to 210℃, not many heating surfaces are required, so it is arranged behind the second evaporator. The advantage of this arrangement is that the heat exchange temperature difference is small, the superheater area is sufficient, and the temperature of the superheated steam can be guaranteed to be stable. The fourth module is a denitrification module, and the flue gas temperature is 365℃, which is in the designed denitrification range. Because the flue gas temperature is still relatively high after denitrification, the flue gas temperature is about 350℃. If the economizer module is used directly, the economizer will boil due to the excessively high flue gas temperature, so the third evaporator is also required. The flue gas temperature at the outlet of the third evaporator is 265℃, and the economizer module is used to continue cooling to 150℃. At this time, the inlet water level of the economizer module is 104°C, and the outlet water temperature is 182°C, which is not boiling. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the front view of the utility model.

[0033] Figure 2 It is a side view of the utility model.

[0034] Figure 3 This is a front view of the SCR flue 6 of the utility model.

[0035] Among them: 1. Expansion joint; 2. Flue gas inlet pipe; 3. Evaporator I; 4. Evaporator II; 5. Superheater; 6. SCR flue; 7. Evaporator III; 8. Connecting flue; 9. Economizer; 10. Flue gas outlet pipe; 11. Steel frame; 12. Boiler drum; 13. Downcomer; 14. Upcomer; 15. Lower header; 16. Upper header; 17. Tube bundle;

[0036] 601, spray gun interface; 602, turbulence zone; 603, rectification zone; 604, reaction zone. DETAILED DESCRIPTION

[0037] The specific implementation of the present utility model is described below in conjunction with the accompanying drawings.

[0038] The utility model relates to the technical field of waste heat boilers, and in particular to a modular waste heat boiler with an SCR flue 6. It includes a steel frame 11, the upper part of the steel frame 11 fixes a boiler drum, and the lower part of the steel frame 11 is a plurality of modules, and the modules include a plurality of evaporator modules, a superheater 5, an SCR flue 6, and an economizer 9. The evaporator modules mainly include evaporator I3, evaporator II4, and evaporator III7. The modules are connected on site by flues. The utility model adopts light tube heat exchange in the high-temperature zone of flue gas, and spiral finned tubes to enhance heat exchange in the low-temperature zone of flue gas, reasonably arranges the heating surface, and is provided with an SCR flue 6 for flue gas denitrification; the waste heat boiler has a compact structure, is modularized at the factory, and is quick and convenient to install, which can reduce the workload of on-site welding, improve the overall quality of the boiler, and can reduce the content of nitrogen oxides in the flue gas.

[0039] like Figure 1 As shown, the modular waste heat boiler with SCR flue of this embodiment includes:

[0040] The evaporator module includes multiple evaporators distributed in parallel and removably plugged into the side wall of the boiler to form the evaporation section of the boiler. Each evaporator is modularized. After each module is in place, it is welded and fixed to the connecting flue. At the same time, the heating surface of each evaporator is composed of four groups of headers and tube bundles, one upper header and one lower header and the tube bundle are a group. The advantage is that a single tube group can be manufactured separately first, and then formed into a whole with other tube groups after ensuring the quality is qualified.

[0041] The boiler drum 12 exchanges heat with a plurality of evaporators through a downcomer 13 and an upcomer 14;

[0042] The SCR flue 6 is detachably arranged between the two rear evaporators and is used for denitrifying the flue gas.

[0043] In this embodiment, Figure 1As shown, the evaporator modules are evaporator I3, evaporator II4 and evaporator III7 in the direction of flue gas flow, and the structure of each evaporator includes:

[0044] Steel frame 11, which plays a connecting and supporting role;

[0045] There are four upper headers 16 which are arranged in a horizontally distributed rectangular structure, and the upper headers 16 are fixed by a steel frame 11;

[0046] There are four lower headers 15 and they are distributed corresponding to the upper headers 16, and multiple groups of tube bundles 17 are arranged between the upper headers 16 and the lower headers 15;

[0047] The upper header 16 is connected to the ascending pipe joint of the boiler drum 12 through the ascending pipe 13 , and the lower header 16 is connected to the descending pipe joint of the boiler drum 12 through the descending pipe 14 .

[0048] In this embodiment, the tube bundle 17 of the evaporator I3 is a plain tube; the tube bundle 17 of the evaporator II4 and the evaporator III7 is a spiral finned tube.

[0049] Regarding the design of the tube segment structure, referring to a finned tube waste heat boiler disclosed in application number CN202121370872.9, the difference in heat exchange effects of the two tube segments is explained in this patent. Because the temperature of the flue gas contacted by the evaporator I3 close to the flue gas entry direction is higher, the tube segments of the bare tube can meet the heat exchange requirements without the need to increase the contact area. The high-temperature flue gas has a lower temperature after heat exchange. When the flue gas contacts another subsequent evaporator, the contact area is increased by using spiral finned tube segments, thereby meeting the heat exchange effect.

[0050] In this embodiment, a flue gas inlet pipe 2 is arranged on the left side of the evaporator I3, a central connecting flue 8 is arranged between the modules, a superheater 5 is arranged on the right side of the evaporator II4, an SCR flue 6 is arranged between the superheater 5 and the evaporator III7, and a flue gas outlet pipe 10 is connected to the right side of the economizer 9.

[0051] The modular waste heat boiler with SCR flue of this embodiment further includes:

[0052] A smoke inlet pipe 2, which is arranged at the smoke inlet end for smoke to enter;

[0053] A superheater 5, which is arranged between the evaporator II4 and the SCR flue 6, and is used to further heat the flue gas from the saturation temperature to the superheat temperature;

[0054] Connecting the flue 8 for installing the SCR flue 6;

[0055] A flue gas outlet pipe 10 is provided to facilitate the outflow of flue gas;

[0056] The economizer 9 is connected to the flue gas outlet pipe 10 and is used to recover the waste heat of the exhaust gas.

[0057] In this embodiment, the SCR flue 6 is provided with the following components in sequence along the flue gas inlet direction:

[0058] Spray gun interface 601, used to connect a spray gun to provide ammonia water;

[0059] The disturbance zone 602 forces the flue gas to be disturbed, so that the flue gas and the ammonia water are fully mixed;

[0060] The rectifying area 603 changes the smoke from a turbulent state to a uniform and stable state;

[0061] In the reaction zone 604, under the action of the catalyst, the flue gas undergoes an oxidation-reduction reaction, and NOx reacts to generate N2 and H2O, completing the denitration function of the flue gas.

[0062] The specific structural functions are as follows:

[0063] like Figure 1 and Figure 2 In the illustrated embodiment, it mainly includes a steel frame 111, a boiler drum 13 is fixed on the upper part of the steel frame 111, and an inlet flue 2, an evaporator I3, an evaporator II4, a superheater 5, an SCR flue 6, an evaporator III7, and an economizer 9 are arranged on the lower part of the steel frame 111.

[0064] Four upper headers 16 are arranged at the upper part of each evaporator module, and four lower headers 15 are arranged at the lower part of the evaporator module. The upper headers 16 are supported on the steel frame 11 of the evaporator module; multiple groups of tube bundles 17 are arranged between the upper headers 16 and the lower headers 15, and the water inlet and outlet ends of each tube bundle 17 are respectively connected to the lower header 15 and the upper header 16. The lower header 15 of each evaporator module is connected to the rising pipe joint of the drum 12 through the rising pipe 13, and the upper header 16 of each evaporator module is connected to the descending pipe joint of the drum 12 through the descending pipe 14; the lower header 15 is only suspended by the tube bundle 17. The tube bundle 17 of the evaporator I3 is a bare tube; the tube bundle 17 of the evaporator II4 and the evaporator III7 is a spiral finned tube. A flue gas inlet pipe 2 is arranged on the left side of the evaporator I3, a central connecting flue 8 is arranged between the modules, a superheater 5 is arranged on the right side of the evaporator II4, an SCR flue 6 is arranged between the superheater 5 and the evaporator III7, and an outlet flue 10 is connected to the right side of the economizer 9.

[0065] like Figure 1 and Figure 2 In the illustrated embodiment, the four lower headers 15 of the evaporator are connected to the ascending pipe joints of the drum 12 through the ascending pipes 13 , respectively. The four upper headers 16 of the evaporator are connected to the descending pipe joints of the drum 12 through the descending pipes 14 .

[0066] like Figure 1 and Figure 2 In the shown embodiment, a flue gas inlet pipe 2 is arranged on the left side of the evaporator I3, and the flue inlet pipe 2 has an expansion joint 1. The high-temperature flue gas enters the evaporator I3 through the flue gas inlet pipe 2 and exchanges heat with the medium in the tube bundle 17. A connecting flue 8 is arranged between each module. The right side of the evaporator I3 is connected to the evaporator II4, the right side of the evaporator II4 is connected to the superheater 5, the right side of the superheater 5 is connected to the SCR flue 6, the right side of the SCR flue 6 is connected to the evaporator III7, the right side of the evaporator III7 is connected to the economizer 9, and the right side of the economizer 9 is connected to the flue gas outlet pipe 10.

[0067] like Figure 3 In the embodiment shown, the SCR flue 6 is provided with a spray gun interface 601, and the flue gas passes through the disturbance zone 602, the rectification zone 603, and the reaction zone 604 in sequence. After the flue gas enters the SCR flue 6, it mixes with the ammonia water sprayed by the spray gun, and then enters the disturbance zone 602, where the disturbance device can force the flue gas to be disturbed, so that the flue gas and the ammonia water are fully mixed, and then enters the rectification zone 603, where the rectification device changes the flue gas from a turbulent state to a uniform and stable state, and then the flue gas enters the reaction zone 604, and under the action of the catalyst, the flue gas undergoes an oxidation-reduction reaction, and NO x The reaction generates N2 and H2O, completing the denitrification function of the flue gas.

[0068] The working principle and use process of the utility model: After the utility model is installed, the waste heat flue gas passes through the evaporator I3, evaporator II4, superheater 5, SCR flue 6, evaporator III7 and economizer 9 in sequence. When the hot flue gas enters the evaporators I3, II, and III, it exchanges heat with the internal tube bundle 17 and generates steam. The steam enters the drum 12 through the riser 14. After the hot flue gas comes out of the evaporator II4, it enters the superheater 5 and exchanges heat with the tube bundle in the superheater 5 to generate superheated steam. Then the hot flue gas enters the SCR flue 6 for flue gas denitrification to reduce the nitrogen oxide content in the flue gas. The hot flue gas then enters the economizer 9, exchanges heat with the internal spiral finned tubes to generate hot water, which enters the drum 12 through the water supply pipe. The utility model is quick and convenient to install, and can not only generate superheated steam, but also reduce nitrogen oxides in the flue gas.

[0069] In this embodiment, the inlet flue gas temperature of the first evaporator is as high as 900°C, which is suitable for using light tubes. The inlet flue gas temperature of the second evaporator is 713°C, and finned tubes can be used at this temperature to reduce weight and volume. The third module is a superheater, and the inlet flue gas temperature is 390°C. Because the slightly superheated steam 208 is superheated to 210°C, not much heating surface is required, so it is arranged behind the second evaporator. The advantage of this arrangement is that the heat exchange temperature difference is small and the superheater area is sufficient to ensure the stability of the superheated steam temperature.

[0070] The fourth module is the denitration module, and the flue gas temperature is 365℃, which is within the designed denitration range. Because the flue gas temperature is still relatively high after denitration, the flue gas temperature is about 350℃. If the economizer module is used directly, the economizer will boil due to the excessive flue gas temperature, so the third evaporator is also required. The flue gas temperature at the outlet of the third evaporator is 265℃, and the economizer module is used to continue cooling it down to 150℃. At this time, the inlet water level of the economizer module is 104℃, and the outlet water temperature is 182℃, which is not boiling.

[0071] At the same time, according to the flue gas temperature, light tubes and spiral fin tubes are used to enhance heat exchange, improve the heat exchange efficiency of the boiler heat exchange components, and make full use of the heat of the hot flue gas; at the same time, the volume of the waste heat boiler is improved, the weight is reduced, and an SCR flue 6 is provided to achieve modular factory delivery of the heating surface, ensure the quality of the boiler, achieve quick on-site assembly, and have a flue gas denitrification function.

[0072] The above description is an explanation of the utility model, not a limitation of the utility model. The scope of the utility model is defined by the claims. Any form of modification can be made within the protection scope of the utility model.

Claims

1. A modular waste heat boiler with an SCR flue, characterized in that: include: The evaporator module includes a plurality of evaporators arranged in parallel and detachably plugged into the side wall of the boiler to form an evaporation section; A boiler drum (12) which exchanges heat with a plurality of evaporators respectively through a downcomer (13) and an upcomer (14); The SCR flue (6) is detachably arranged between the two rear evaporators and is used to denitrate the flue gas.

2. A modular waste heat boiler with an SCR flue as claimed in claim 1, characterized in that: The evaporator modules are evaporator I (3), evaporator II (4) and evaporator III (7) in order along the flue gas flow direction, and the structure of each evaporator includes: A steel frame (11) which serves as a connecting support; There are four upper headers (16) which are arranged in a horizontally distributed rectangular structure, and the plurality of upper headers (16) are fixed by a steel frame (11); There are four lower headers (15) distributed corresponding to the upper headers (16), and a plurality of tube bundles (17) are arranged between the upper headers (16) and the lower headers (15); The upper header (16) is connected to the ascending pipe joint of the boiler drum (12) via the ascending pipe (14), and the lower header (15) is connected to the descending pipe joint of the boiler drum (12) via the descending pipe (13).

3. A modular waste heat boiler with an SCR flue as claimed in claim 2, characterized in that: The tube bundle (17) of the evaporator I (3) is a plain tube; the tube bundle (17) of the evaporator II (4) and the evaporator III (7) is a spiral finned tube.

4. A modular waste heat boiler with an SCR flue as claimed in claim 2, characterized in that: A flue gas inlet pipe (2) is arranged on the left side of the evaporator I (3), a central connecting flue (8) is arranged between the modules, a superheater (5) is arranged on the right side of the evaporator II (4), an SCR flue (6) is arranged between the superheater (5) and the evaporator III (7), and a flue gas outlet pipe (10) is connected to the right side of the economizer (9).

5. A modular waste heat boiler with an SCR flue as claimed in claim 2, characterized in that: Also includes: A smoke inlet pipe (2), which is arranged at the smoke inlet end and is used for smoke to enter; A superheater (5), which is arranged between the evaporator II (4) and the SCR flue (6), and is used to further heat the flue gas from the saturation temperature to the superheat temperature; Connecting flue (8) for installing SCR flue (6); A flue gas outlet pipe (10) for facilitating the outflow of flue gas; The economizer (9) is connected to the flue gas outlet pipe (10) and is used to recover the waste heat of the exhaust gas.

6. A modular waste heat boiler with an SCR flue as claimed in claim 1, characterized in that: The SCR flue (6) is provided with the following components in sequence along the flue gas inlet direction: A spray gun interface (601) is used to connect a spray gun to provide ammonia water; The turbulence zone (602) causes forced disturbance of the flue gas, so that the flue gas and the ammonia solution are fully mixed; The rectifying zone (603) changes the smoke from a turbulent state to a uniform and stable state; In the reaction zone (604), under the action of the catalyst, the flue gas undergoes an oxidation-reduction reaction, and NO x The reaction generates N2 and H2O, completing the denitrification function of the flue gas.

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