An incineration flue gas waste heat recovery heat exchanger material selection experimental system and method

Abstract

The present application relates to the field of waste incineration power generation, and discloses a kind of incineration flue gas waste heat recovery heat exchanger material selection experiment system and method, comprising: flue gas is introduced unit, heat exchanger main part, test sleeve unit, waterway heat exchange unit, condensate water collection unit, flue gas mixing discharge unit and parameter monitoring unit;Method steps are: experimental preparation work is carried out, adjusts condensate flow, adjusts flue gas flow, system stable operation, adjusts corresponding air fan flow, after system stable operation one detection period, sleeve sampling analysis is carried out, and the next cycle experiment is carried out by replacing sleeve;The present application solves the problem that the prior art considers practicability and economy under the condition, develops the heat exchanger suitable for adaptation, realizes the cost reduction and benefit increase of incineration plant, provides basis for the selection and manufacturing of heat exchanger.

Description

Technical Field

[0001] This invention relates to the field of waste incineration power generation, and in particular to an experimental system and method for selecting materials for a heat exchanger for recovering waste heat from incineration flue gas. Background Technology

[0002] Waste-to-energy incineration systems convert combustible components of waste into heat energy, which is then used to generate electricity through a thermoelectric conversion system. This achieves the reduction, harmlessness, and resource recovery of waste, and is an important aspect of building a "zero-waste city."

[0003] Currently, waste-to-energy incineration faces significant heat loss issues. The flue gas outlet temperature of waste incinerators and waste heat boilers typically exceeds 200℃. After treatment by the flue gas purification system, the emission temperature is generally 130-150℃, meaning approximately 15% of the total incineration heat is lost with the flue gas and cannot be effectively recovered. Existing flue gas recovery technologies, for corrosion prevention reasons, only reduce the flue gas temperature from 130-150℃ to slightly above 100℃, recovering only a portion of the sensible heat. It is worth noting that the moisture content of waste incineration flue gas reaches 20%-25%, containing a considerable latent heat of vaporization. Therefore, accurately analyzing the acid dew point characteristics of flue gas under different operating conditions, and selecting corrosion-resistant heat exchanger materials to further reduce the exhaust temperature below the water dew point (60-65℃), achieving deep recovery and utilization of flue gas waste heat, is crucial for reducing operating costs, improving energy efficiency, and reducing carbon emissions in waste incineration plants. Summary of the Invention

[0004] The present invention aims to provide an experimental system and method for material selection of incineration flue gas waste heat recovery heat exchangers, in order to solve the problem in the existing technology of developing suitable heat exchangers while taking into account practicality and economy, so as to achieve cost reduction and efficiency improvement in incineration plants and provide a basis for heat exchanger selection and manufacturing.

[0005] To achieve the above objectives, the present invention provides the following method:

[0006] The present invention provides an experimental system for material selection of incineration flue gas waste heat recovery heat exchangers:

[0007] The system includes: a flue gas conveying unit, a heat exchanger body, a test sleeve unit, a water heat exchange unit, a condensate collection unit, a flue gas mixing and emission unit, and a parameter monitoring unit;

[0008] The flue gas delivery unit includes a variable frequency induced draft fan. The inlet of the variable frequency induced draft fan is connected to the chimney of the waste incineration plant. The outlet is divided into a main path and a bypass path. Both the main path and the bypass path are equipped with electric valves and check valves. The main path is connected to the flue gas inlet of the heat exchanger body, and the bypass path is connected to the flue gas mixer inlet of the flue gas mixing and emission unit.

[0009] The heat exchanger body is a gas-water tube heat exchanger. Along the flue gas flow direction, it consists of a flue gas duct A without heat exchange tubes, four heat exchange tube bundles a / b / c / d, and a flue gas duct E without heat exchange tubes. Heat exchange chambers B / C / D are sequentially arranged between the four heat exchange tube bundles a / b / c / d. Connecting water pipes between adjacent heat exchange tube bundles are installed within heat exchange chambers B / C / D. Flue gas ducts A and E are equipped with sleeve insertion ports, and heat exchange chambers B / C / D are equipped with multiple test sleeve interfaces. Along the flue gas flow direction, the materials of the four heat exchange tube bundles a / b / c / d are, in order, carbon steel, ND steel, 316L stainless steel, and 2205 stainless steel.

[0010] The test sleeve unit includes several test sleeves. The test sleeves are connected to the sleeve insertion port and the test sleeve interface flange. The test sleeve includes a flange port, a metal pipe cavity and a built-in air pipe. The cold air inlet of the air pipe is connected to a fan and a regulating valve. Temperature measuring points are provided on the outer surface of the test sleeve and are used to wrap the metal sheet to be tested.

[0011] The water heat exchange unit is connected to the internal water channels of the four heat exchange tube bundles a / b / c / d, and adopts a gas-water countercurrent heat exchange method. Cold water enters from the low-temperature section of the heat exchanger body and hot water flows out from the high-temperature section.

[0012] The condensate collection unit includes condensate collection boxes and sampling ports located at the bottom of the four heat exchange tube bundles. The drain pipe of the condensate collection box is connected to the sewage treatment system.

[0013] The flue gas mixing and emission unit includes a flue gas mixer and a chimney. The low-temperature flue gas from the heat exchanger body enters the flue gas mixer through the flue gas pipe E, mixes with the bypass unheated flue gas, and is then discharged from the chimney.

[0014] The parameter monitoring unit includes temperature, pressure, and flow measurement points installed in flue gas ducts A / E and heat exchange chambers B / C / D, for real-time monitoring of flue gas parameters.

[0015] Preferably, the water heat exchange unit includes a water supply pump, a regulating valve, and a hot water tank. The inlet of the water supply pump is connected to condensate or demineralized water at 28-32°C from the incineration plant, and the outlet is connected to the internal water inlet of the heat exchange tube bundle d via the regulating valve. The internal water outlet of the heat exchange tube bundle a is connected to the hot water tank. The outlet of the hot water tank is equipped with a water supply pump and connected to the deaerator of the incineration plant. The heated water enters the deaerator or the next stage heater according to the operating conditions of the incineration plant.

[0016] Preferably, the temperature range for flue gas treatment is 60-150℃, and the flue gas being treated is compliant with GB18485-2014 emission standards after being treated by the waste incineration flue gas purification system, with an initial flue gas temperature of 130-150℃.

[0017] Preferably, the metal pipe cavity of the test sleeve is a closed structure. After the cold air enters the air pipe through the fan, it absorbs heat to form hot air and flows out of the pipe. The cold air flow rate is adjusted by the regulating valve to accurately control the wall temperature of the metal sheet to be tested on the outer surface of the test sleeve.

[0018] This invention discloses an experimental method for selecting materials for a waste heat recovery heat exchanger from incineration flue gas, characterized by the following steps:

[0019] S1. Experimental preparation: According to the specifications of the metal material to be tested, cut the corresponding metal sheet and wrap it around the outer surface of each test sleeve. Connect the flange of the wrapped test sleeve to the sleeve insertion port of the heat exchanger body and the test sleeve interface of the heat exchange cavity. Check the sealing performance and normal working condition of each pipeline, valve, measuring point and unit.

[0020] S2. Flue gas delivery and operating condition adjustment: Start the variable frequency induced draft fan, open the main electric valve, and deliver the purified 130-150℃ flue gas from the waste incineration plant chimney to the heat exchanger body. Adjust the flue gas flow rate through the variable frequency induced draft fan and adjust the bypass flue gas flow rate through the opening of the bypass electric valve. Set the basic operating conditions of the flue gas for the experiment.

[0021] S3, Water circuit heat exchange start-up: Start the water supply pump of the water circuit heat exchange unit to transport the incinerator condensate / demineralized water to the heat exchange tube bundle d in the low temperature section of the heat exchanger body through the regulating valve, so as to realize the reverse heat exchange between water and flue gas. The water flow rate is adjusted by the regulating valve to control the cooling rate of the flue gas, so that the flue gas temperature along the flue gas flow direction in the heat exchanger body gradually drops to 60℃.

[0022] S4. Test sleeve wall temperature control: Start the fan of the test sleeve unit, open the regulating valve of the cold air inlet, and introduce cold air into the air pipe of the test sleeve. Control the cold air flow by adjusting the opening of the regulating valve, and adjust the wall temperature of the metal sheet to be tested on the outer surface of each test sleeve to the experimental set value. Use the parameter monitoring unit to record the flue gas temperature, pressure, flow parameters and test sleeve wall temperature parameters in real time in the flue gas pipe and heat exchange chamber.

[0023] S5. Condensate collection and sampling: During the heat exchange process, condensate is collected from the condensate collection tank at the bottom of each heat exchange tube bundle. The condensate in each heat exchange section is sampled periodically through the sampling port on the drain pipe to test the acidity and concentration of the condensate.

[0024] S6. Multi-condition corrosion test: By adjusting the air volume of the variable frequency induced draft fan, the water flow rate of the water circuit regulating valve, and the cold air flow rate of the test sleeve, the flue gas conditions, heat exchange temperature, and metal sheet wall temperature are changed to carry out metal corrosion tests under multiple conditions and continuously set the test duration.

[0025] S7. Corrosion Detection and Analysis: After the experiment, the metal sheet outside the test sleeve was removed, and the corrosion degree and surface morphology of the metal sheet were detected. Combined with the flue gas parameters and condensate parameters under various working conditions, the corrosion resistance characteristics of each metal material under different wall temperatures and flue gas ambient temperatures were analyzed.

[0026] S8. Material Selection: Based on corrosion detection and analysis results, and combined with the cost of each metal material, determine the suitable materials for each heat exchange section of the heat exchanger within the flue gas temperature range of 60-150℃, and form a heat exchanger material selection scheme.

[0027] Preferably, in step S3, the counter-current heat exchange between flue gas and water satisfies the following: the flue gas gradually cools down along the flow direction of heat exchange tube bundle a / b / c / d, and the water gradually heats up along the flow direction of heat exchange tube bundle d / c / b / a. The high-temperature section of the flue gas and the high-temperature section of the water coincide at point a of the heat exchange tube bundle.

[0028] Preferably, in step S5, the condensate collected in the condensate collection tank is collected by the drain pipe and then transported to the sewage treatment system to avoid pollution caused by the direct discharge of acidic condensate.

[0029] Preferably, in step S6, the variables in the multi-condition experiment include flue gas velocity, flue gas temperature, water flow rate, metal sheet wall temperature, and acid gas concentration, and the adjustment range of each variable matches the actual operating conditions of the waste incineration plant.

[0030] Preferably, in step S8, the heat exchanger material selection scheme should take into account both the corrosion resistance and cost economy of the material. 2205 stainless steel is selected in the low temperature corrosion high incidence range of 60-80℃, 316L stainless steel is selected in the range of 80-100℃, ND steel is selected in the range of 100-120℃, and carbon steel is selected in the range of 120-150℃.

[0031] Preferably, during the experiment, if the temperature of the low-temperature flue gas discharged from the heat exchanger body is too low, the bypass electric valve is opened to allow the bypass unheated flue gas to mix with the low-temperature flue gas in the flue gas mixer, thereby increasing the flue gas emission temperature and preventing corrosion of the flue inside the chimney.

[0032] The beneficial effects of this invention are as follows: 1. By using the actual flue gas emitted by a waste incineration plant as the experimental input, this invention can accurately reflect the actual engineering situation compared to the immersion experiment.

[0033] 2. The use of a sleeve-type experimental system allows for multi-condition experiments to be conducted within one experimental cycle, effectively accelerating the experimental progress.

[0034] 3. All corrosion tests are destructive tests. Using a sleeve-type heat exchanger is not only easier to replace than manufacturing complete heat exchangers of different materials, but also reduces equipment investment. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0036] Figure 1 This is a schematic diagram of an experimental system for selecting materials for a waste heat recovery heat exchanger from incineration flue gas, provided in an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the cavity provided in an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of the sleeve provided in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of an experimental method for selecting materials for a waste heat recovery heat exchanger from incineration flue gas, provided in an embodiment of the present invention.

[0040] Figure labels: 1-Waste incineration plant chimney, 2-Variable frequency induced draft fan, 3-Hot water tank, 401-Flue gas duct A, 402-Heat exchange tube bundle a, 403-Condensate drain pipe a1, 501-Heat exchange cavity B, 502-Heat exchange tube bundle b, 503-Condensate drain pipe b1, 601-Heat exchange cavity C, 602-Heat exchange tube bundle c, 603-Condensate drain pipe c1, 701-Heat exchange cavity D, 702-Heat exchange tube bundle d, 703-Condensate drain pipe d1, 8-Flue gas duct E, 9-Flue gas mixer, 10-Flue gas duct F, 11-Chimney, 12-Condensate discharge, 13-Condensate drain, 14-Flange, 15-Heat exchanger tube, 16-Cold air inlet, 17-Hot air inlet, 18-Test sleeve. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or end that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or ends.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] Currently, waste-to-energy incineration faces significant heat loss issues. The flue gas outlet temperature of waste incinerators and waste heat boilers typically exceeds 200℃. After treatment by the flue gas purification system, the emission temperature is generally 130-150℃, meaning approximately 15% of the total incineration heat is lost with the flue gas and cannot be effectively recovered. Existing flue gas recovery technologies, for corrosion prevention reasons, only reduce the flue gas temperature from 130-150℃ to slightly above 100℃, recovering only a portion of the sensible heat. It is worth noting that the moisture content of waste incineration flue gas reaches 20%-25%, containing a considerable latent heat of vaporization. Therefore, accurately analyzing the acid dew point characteristics of flue gas under different operating conditions, and selecting corrosion-resistant heat exchanger materials to further reduce the exhaust temperature below the water dew point (60-65℃), achieving deep recovery and utilization of flue gas waste heat, is crucial for reducing operating costs, improving energy efficiency, and reducing carbon emissions in waste incineration plants.

[0045] The present invention aims to provide an experimental system and method for material selection of incineration flue gas waste heat recovery heat exchangers, in order to solve the problem in the existing technology of developing suitable heat exchangers while taking into account practicality and economy, so as to achieve cost reduction and efficiency improvement in incineration plants and provide a basis for heat exchanger selection and manufacturing.

[0046] like Figures 1-3 As shown in the figure, a specific embodiment of the present invention provides an experimental system for material selection of a waste heat recovery heat exchanger for incineration flue gas, the system comprising:

[0047] The system includes a flue gas delivery unit, a heat exchanger body, 18 test sleeve units, a water heat exchange unit, a condensate collection unit, a flue gas mixing and emission unit, and a parameter monitoring unit.

[0048] The flue gas delivery unit includes a variable frequency induced draft fan 2. The inlet of the variable frequency induced draft fan 2 is connected to the chimney 1 of the waste incineration plant. The outlet is divided into a main road and a bypass road. Both the main road and the bypass road are equipped with electric valves and check valves. The main road is connected to the flue gas inlet of the heat exchanger body, and the bypass road is connected to the inlet of the flue gas mixer 9 of the flue gas mixing and emission unit.

[0049] The heat exchanger body is a gas-water tube heat exchanger. Along the flue gas flow direction, it consists of a flue gas duct A401 without heat exchange tubes, four heat exchange tube bundles a402 / b502 / c602 / d702, and a flue gas duct E8 without heat exchange tubes. Heat exchange chambers B501 / C601 / D701 are sequentially arranged between the four heat exchange tube bundles a402 / b502 / c602 / d702. Heat exchange chambers B501 / C602 / D701... 601 / D701 is equipped with connecting water pipes for adjacent heat exchange tube bundles, and flue gas pipes A401 and E8 are equipped with sleeve insertion ports. Heat exchange chambers B501 / C601 / D701 are equipped with multiple test sleeve 18 interfaces. Along the flue gas flow direction, the materials of the four heat exchange tube bundles a402 / b502 / c602 / d702 are carbon steel, ND steel, 316L stainless steel, and 2205 stainless steel, respectively.

[0050] The test sleeve 18 unit includes several test sleeves 18, which are connected to the sleeve insertion port and the test sleeve 18 interface flange 14. The test sleeve 18 includes the flange 14 port, a metal pipe cavity and an internal air pipe. The cold air inlet of the air pipe is connected to a fan and a regulating valve. Temperature measuring points are set on the outer surface of the test sleeve 18 and used to wrap the metal sheet to be tested. The metal pipe cavity of the test sleeve 18 is a closed structure. After the cold air enters the air pipe through the fan, it absorbs heat to form hot air and flows out of the pipe. The cold air flow rate is adjusted by the regulating valve to accurately control the wall temperature of the metal sheet to be tested on the outer surface of the test sleeve 18.

[0051] The water heat exchange unit is connected to the internal water channels of the four heat exchange tube bundles a402 / b502 / c602 / d702, and adopts a gas-water countercurrent heat exchange method. Cold water enters from the low-temperature section of the heat exchanger body and hot water flows out from the high-temperature section. The water heat exchange unit includes a water pump, a regulating valve, and a hot water tank 3. The inlet of the water pump is connected to the condensate or demineralized water at 28~32℃ of the incineration plant, and the outlet is connected to the internal water inlet of the heat exchange tube bundle d702 via the regulating valve. The internal water outlet of the heat exchange tube bundle a402 is connected to the hot water tank 3. The outlet of the hot water tank 3 is equipped with a water pump and is connected to the deaerator of the incineration plant. The heated water enters the deaerator or the next stage heater according to the operating conditions of the incineration plant. The temperature range of the flue gas treatment is 60-150℃. The treated flue gas is compliant with the GB18485-2014 emission standard after being treated by the waste incineration flue gas purification system, and the initial temperature of the flue gas is 130-150℃.

[0052] The condensate collection unit includes condensate collection tanks and sampling ports located at the bottom of the four heat exchange tube bundles. The drain pipe of the condensate collection tank is connected to the sewage treatment system.

[0053] The flue gas mixing and emission unit includes a flue gas mixer 9 and a chimney 11. The low-temperature flue gas from the heat exchanger body enters the flue gas mixer 9 through the flue gas duct E8, mixes with the bypass non-heat exchanged flue gas, and is then discharged from the chimney 11.

[0054] The parameter monitoring unit includes temperature, pressure and flow measurement points installed in flue gas ducts A401 / E8 and heat exchange chambers B501 / C601 / D701, for real-time monitoring of flue gas parameters.

[0055] like Figure 4 As shown, this invention discloses an experimental method for selecting materials for a waste heat recovery heat exchanger from incineration flue gas, characterized by the following steps:

[0056] S1. Experimental preparation: According to the specifications of the metal material to be tested, cut the corresponding metal sheet and wrap it on the outer surface of each test sleeve 18. Connect the flange 14 of the wrapped test sleeve 18 to the sleeve insertion port of the heat exchanger body and the test sleeve 18 interface of the heat exchange cavity. Check the sealing performance and normal working condition of each pipeline, valve, measuring point and unit.

[0057] S2. Flue gas delivery and operating condition adjustment: Start the variable frequency induced draft fan 2, open the main electric valve, and deliver the purified 130-150℃ flue gas from the waste incineration plant chimney 111 to the heat exchanger body. Adjust the flue gas flow rate through the variable frequency induced draft fan 2, and adjust the bypass flue gas flow rate through the opening of the bypass electric valve to set the basic flue gas operating conditions for the experiment.

[0058] S3. Start-up of water heat exchange: Start the water supply pump of the water heat exchange unit to deliver the incinerator condensate / demineralized water to the heat exchange tube bundle d702 in the low-temperature section of the heat exchanger body through the regulating valve, so as to realize the reverse heat exchange between water and flue gas. The water flow rate is adjusted by the regulating valve to control the cooling rate of the flue gas, so that the temperature of the flue gas along the flue gas flow direction in the heat exchanger body gradually drops to 60℃.

[0059] In this embodiment of the invention, the counter-current heat exchange between flue gas and water satisfies the following: the flue gas gradually cools down along the flow direction of the heat exchange tube bundles a402 / b502 / c602 / d702, while the water gradually heats up along the flow direction of the heat exchange tube bundles d702 / c602 / b502 / a402, and the high-temperature section of the flue gas and the high-temperature section of the water coincide at the heat exchange tube bundle a402.

[0060] S4. Test sleeve 18 wall temperature control: Start the fan of the test sleeve 18 unit, open the regulating valve of the cold air inlet, and introduce cold air into the air duct of the test sleeve 18. Control the cold air flow by adjusting the opening of the regulating valve, and adjust the wall temperature of the metal sheet to be tested on the outer surface of each test sleeve 18 to the experimental set value. Use the parameter monitoring unit to record the flue gas temperature, pressure, flow parameters and the wall temperature parameters of the test sleeve 18 in real time in the flue gas duct and heat exchange chamber.

[0061] S5. Condensate Collection and Sampling: During the heat exchange process, condensate is collected from the condensate collection tanks at the bottom of each heat exchange tube bundle. The condensate in each heat exchange section is sampled periodically through the sampling port on the drain pipe to test the acidity and concentration of the condensate.

[0062] In this embodiment of the invention, the condensate collected by the condensate collection tank is transported to the sewage treatment system via the drain pipe, thus avoiding pollution caused by the direct discharge of acidic condensate.

[0063] S6. Multi-condition corrosion test: By adjusting the air volume of the variable frequency induced draft fan 2, the water flow rate of the water circuit regulating valve, and the cold air flow rate of the test sleeve 18, the flue gas conditions, heat exchange temperature, and metal sheet wall temperature are changed to carry out metal corrosion tests under multiple conditions, and the test duration is continuously set.

[0064] In this embodiment of the invention, the variables in the multi-condition experiment include flue gas velocity, flue gas temperature, water flow rate, metal sheet wall temperature, and acid gas concentration. The adjustment range of each variable matches the actual operating conditions of the waste incineration plant.

[0065] S7. Corrosion Detection and Analysis: After the experiment, the metal sheet outside the test sleeve 18 was removed, and the corrosion degree and surface morphology of the metal sheet were detected. Combined with the flue gas parameters and condensate parameters under various working conditions, the corrosion resistance characteristics of each metal material under different wall temperatures and flue gas ambient temperatures were analyzed.

[0066] S8. Material Selection: Based on corrosion detection and analysis results, and combined with the cost of each metal material, determine the suitable materials for each heat exchange section of the heat exchanger within the flue gas temperature range of 60-150℃, and form a heat exchanger material selection scheme.

[0067] In this embodiment of the invention, the heat exchanger material selection scheme needs to take into account both the corrosion resistance and cost economy of the material. 2205 stainless steel is selected in the high-incidence low-temperature corrosion range of 60-80℃, 316L stainless steel is selected in the range of 80-100℃, ND steel is selected in the range of 100-120℃, and carbon steel is selected in the range of 120-150℃. During the experiment, if the low-temperature flue gas temperature discharged from the heat exchanger body is too low, the bypass electric valve is opened to mix the bypass unheated flue gas with the low-temperature flue gas in the flue gas mixer 9, thereby increasing the flue gas emission temperature and avoiding corrosion of the flue inside the chimney 11.

[0068] Example 1:

[0069] The system includes:

[0070] The system includes a flue gas delivery unit, a heat exchanger body, 18 test sleeve units, a water heat exchange unit, a condensate collection unit, a flue gas mixing and emission unit, and a parameter monitoring unit.

[0071] The flue gas delivery unit includes a variable frequency induced draft fan 2. The inlet of the variable frequency induced draft fan 2 is connected to the chimney 1 of the waste incineration plant. The outlet is divided into a main road and a bypass road. Both the main road and the bypass road are equipped with electric valves and check valves. The main road is connected to the flue gas inlet of the heat exchanger body, and the bypass road is connected to the inlet of the flue gas mixer 9 of the flue gas mixing and emission unit.

[0072] The main body of the heat exchanger is a gas-water tube heat exchanger. Along the flue gas flow direction, there are sequentially arranged flue gas ducts A401 (without heat exchange tube bundles), four heat exchange tube bundles a402 / b502 / c602 / d702, and a flue gas duct E8 (without heat exchange tube bundles). Heat exchange chambers B501 / C601 / D701 are sequentially arranged between the four heat exchange tube bundles a402 / b502 / c602 / d702. Connecting water pipes between adjacent heat exchange tube bundles are installed within heat exchange chambers B501 / C601 / D701. Flue gas ducts A401 and E8 are also equipped with… The heat exchange chambers B501 / C601 / D701 are equipped with multiple test sleeve 18 interfaces at the sleeve insertion port; along the flue gas flow direction, the materials of the four heat exchange tube bundles a402 / b502 / c602 / d702 are carbon steel, ND steel, 316L stainless steel, and 2205 stainless steel, respectively. The four heat exchange tube bundles a402 / b502 / c602 / d702 are respectively connected to condensate drain pipes a1403, b1503, c1603, and d1703 below them.

[0073] The test sleeve 18 unit includes several test sleeves 18, which are connected to the sleeve insertion port and the test sleeve 18 interface flange 14. The test sleeve 18 includes the flange 14 port, the metal pipe cavity and the built-in air pipe. The cold air inlet 16 of the air pipe is connected to the variable frequency fan 2 and the regulating valve. Temperature measuring points are set on the outer surface of the test sleeve 18 and used to wrap the metal sheet to be tested. The metal pipe cavity of the test sleeve 18 is a closed structure. After the cold air enters the air pipe through the fan, it absorbs heat to form hot air and flows out from the hot air inlet 17 pipe. The cold air flow rate is adjusted by the regulating valve to accurately control the wall temperature of the metal sheet to be tested on the outer surface of the test sleeve 18. The heat exchanger tube 15 is inclined and set inside the cavity.

[0074] The water heat exchange unit is connected to the internal water channels of the four heat exchange tube bundles a402 / b502 / c602 / d702, and adopts a gas-water countercurrent heat exchange method. Cold water enters from the low-temperature section of the heat exchanger body and hot water flows out from the high-temperature section. The water heat exchange unit includes a water pump, a regulating valve, and a hot water tank 3. The inlet of the water pump is connected to the condensate or demineralized water at 28~32℃ of the incineration plant, and the outlet is connected to the internal water inlet of the heat exchange tube bundle d702 via the regulating valve. The internal water outlet of the heat exchange tube bundle a402 is connected to the hot water tank 3. The outlet of the hot water tank 3 is equipped with a water pump and is connected to the deaerator of the incineration plant. The heated water enters the deaerator or the next stage heater according to the operating conditions of the incineration plant. The temperature range of the flue gas treatment is 60-150℃. The treated flue gas is compliant with the GB18485-2014 emission standard after being treated by the waste incineration flue gas purification system, and the initial temperature of the flue gas is 130-150℃.

[0075] The condensate collection unit includes condensate collection tanks and sampling ports located at the bottom of the four heat exchange tube bundles. The drain pipe of the condensate collection tank is connected to the sewage treatment system.

[0076] The flue gas mixing and emission unit includes a flue gas mixer 9 and a chimney 11. The low-temperature flue gas from the heat exchanger body enters the flue gas mixer 9 through the flue gas pipe E8. The flue gas mixer 9 is fixedly connected to the rear end of the flue gas pipe F10 and mixes with the bypass non-heat exchanged flue gas before being discharged from the chimney 11. Condensate is discharged into the device from the condensate discharge 12, and the condensate is collected and discharged from the condensate discharge 13.

[0077] The parameter monitoring unit includes temperature, pressure and flow measurement points installed in flue gas ducts A401 / E8 and heat exchange chambers B501 / C601 / D701, for real-time monitoring of flue gas parameters.

[0078] The beneficial effects of this invention are as follows: 1. By using the actual flue gas emitted by a waste incineration plant as the experimental input, this invention can accurately reflect the actual engineering situation compared to the immersion experiment.

[0079] 2. The use of a sleeve-type experimental system allows for multi-condition experiments to be conducted within one experimental cycle, effectively accelerating the experimental progress.

[0080] 3. All corrosion tests are destructive tests. Using a sleeve-type heat exchanger is not only easier to replace than manufacturing complete heat exchangers of different materials, but also reduces equipment investment.

[0081] The above descriptions are merely embodiments of the present invention. Commonly known technical solutions or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the scope of the present invention, and these should also be considered within the protection scope of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An experimental system for selecting materials for a waste heat recovery heat exchanger from incineration flue gas, characterized in that, The system includes: a flue gas conveying unit, a heat exchanger body, a test sleeve unit, a water heat exchange unit, a condensate collection unit, a flue gas mixing and emission unit, and a parameter monitoring unit; The flue gas delivery unit includes a variable frequency induced draft fan (2). The inlet of the variable frequency induced draft fan (2) is used to connect with the chimney (1) of the waste incineration plant. The outlet is divided into a main road and a bypass road. Both the main road and the bypass road are equipped with electric valves and check valves. The main road is connected to the flue gas inlet of the heat exchanger body. The bypass road is connected to the inlet of the flue gas mixer (9) of the flue gas mixing and emission unit. The heat exchanger body is a gas-water tube heat exchanger. Along the flue gas flow direction, a flue gas duct A (401) without heat exchange tube bundles, four heat exchange tube bundles a (402) / b (502) / c (602) / d (702), and a flue gas duct E (8) without heat exchange tube bundles are arranged sequentially. Heat exchange chambers B (501) / C (601) / D (701) are arranged sequentially between the four heat exchange tube bundles a (402) / b (502) / c (602) / d (702). The heat exchange chamber B (502)... 1) / C(601) / D(701) is provided with connecting water pipes for adjacent heat exchange tube bundles, and flue gas pipes A(401) and E(8) are provided with sleeve insertion ports, and heat exchange chambers B(501) / C(601) / D(701) are provided with multiple test sleeve (18) interfaces; along the flue gas flow direction, the materials of the four heat exchange tube bundles a(402) / b(502) / c(602) / d(702) are carbon steel, ND steel, 316L stainless steel, and 2205 stainless steel, respectively; The test sleeve unit includes several test sleeves (18), the test sleeves (18) are connected to the sleeve insertion port and the test sleeve (18) interface flange (14), the test sleeves (18) include the flange (14) port, the metal pipe cavity and the built-in air pipe, the cold air inlet of the air pipe is connected to the fan and the regulating valve, and the outer surface of the test sleeves (18) is provided with temperature measuring points and used to wrap the metal sheet to be tested; The water heat exchange unit is connected to the internal water circuit of the four heat exchange tube bundles a(402) / b(502) / c(602) / d(702), and adopts a gas-water countercurrent heat exchange method. Cold water enters from the low-temperature section of the heat exchanger body and hot water flows out from the high-temperature section. The condensate collection unit includes condensate collection boxes and sampling ports located at the bottom of the four heat exchange tube bundles. The drain pipe of the condensate collection box is connected to the sewage treatment system. The flue gas mixing and emission unit includes a flue gas mixer (9) and a chimney (11). The low-temperature flue gas from the heat exchanger body enters the flue gas mixer (9) through the flue gas pipe E (8), mixes with the bypass unheated flue gas, and is discharged from the chimney (11). The parameter monitoring unit includes temperature, pressure and flow measurement points installed in flue gas ducts A(401) / E(8) and heat exchange chambers B(501) / C(601) / D(701) for real-time monitoring of flue gas parameters.

2. The experimental system for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 1, characterized in that: The water heat exchange unit includes a water pump, a regulating valve, and a hot water tank (3). The inlet of the water pump is connected to condensate or demineralized water at 28~32℃ in the incineration plant, and the outlet is connected to the internal water inlet of the heat exchange tube bundle d (702) via the regulating valve. The internal water outlet of the heat exchange tube bundle a (402) is connected to the hot water tank (3). The outlet of the hot water tank (3) is equipped with a water pump and connected to the deaerator of the incineration plant. The heated water enters the deaerator or the next stage heater according to the working conditions of the incineration plant.

3. The experimental system for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 1, characterized in that: The temperature range for flue gas treatment is 60-150℃. The flue gas being treated is compliant with GB18485-2014 emission standards after being treated by the waste incineration flue gas purification system, and the initial temperature of the flue gas is 130-150℃.

4. The experimental system for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 1, characterized in that: The metal pipe cavity of the test sleeve (18) is a closed structure. After the cold air enters the air pipe through the fan, it absorbs heat to form hot air and flows out of the pipe. The cold air flow rate is adjusted by the regulating valve to accurately control the wall temperature of the metal sheet to be tested on the outer surface of the test sleeve (18).

5. A method for selecting materials for a waste heat recovery heat exchanger from incineration gas, based on the experimental system for material selection of a waste heat recovery heat exchanger from incineration gas as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Experimental preparation: According to the specifications of the metal material to be tested, cut the corresponding metal sheet and wrap it on the outer surface of each test sleeve (18). Connect the flange (14) of the wrapped test sleeve (18) to the sleeve insertion port of the heat exchanger body and the test sleeve (18) interface of the heat exchange cavity. Check the sealing performance and normal working status of each pipeline, valve, measuring point and unit. S2. Flue gas delivery and operating condition adjustment: Start the variable frequency induced draft fan (2), open the main electric valve, and deliver the purified 130-150℃ flue gas in the waste incineration plant chimney (1) to the heat exchanger body. Adjust the flue gas flow rate through the variable frequency induced draft fan (2), adjust the bypass flue gas flow rate through the opening of the bypass electric valve, and set the basic flue gas operating conditions for the experiment. S3, Water circuit heat exchange start-up: Start the water supply pump of the water circuit heat exchange unit to transport the incinerator condensate / demineralized water to the heat exchange tube bundle d(702) in the low temperature section of the heat exchanger body through the regulating valve, realize the reverse heat exchange between water and flue gas, regulate the water flow rate through the regulating valve to control the cooling rate of flue gas, so that the flue gas temperature along the flue gas flow direction in the heat exchanger body gradually drops to 60℃. S4. Test sleeve (18) wall temperature control: Start the fan of the test sleeve (18) unit, open the regulating valve of the cold air inlet, and introduce cold air into the air pipe of the test sleeve (18). Control the cold air flow by adjusting the opening of the regulating valve, and adjust the wall temperature of the metal sheet to be tested on the outer surface of each test sleeve (18) to the experimental set value. Use the parameter monitoring unit to record the flue gas temperature, pressure, flow parameters and test sleeve (18) wall temperature parameters in real time in the flue gas pipe and heat exchange chamber. S5. Condensate collection and sampling: During the heat exchange process, condensate is collected from the condensate collection tank at the bottom of each heat exchange tube bundle. The condensate in each heat exchange section is sampled periodically through the sampling port on the drain pipe to test the acidity and concentration of the condensate. S6. Multi-condition corrosion test: By adjusting the air volume of the variable frequency induced draft fan (2), the water flow rate of the water circuit regulating valve, and the cold air flow rate of the test sleeve (18), the flue gas conditions, heat exchange temperature, and metal sheet wall temperature are changed to carry out a multi-condition corrosion test of metal materials and continuously set the test duration. S7. Corrosion detection and analysis: After the experiment, remove the metal sheet outside the test sleeve (18), detect the corrosion degree and surface morphology of the metal sheet, and analyze the corrosion resistance characteristics of each metal material under different wall temperatures and flue gas ambient temperatures in combination with flue gas parameters and condensate parameters under various working conditions. S8. Material Selection: Based on corrosion detection and analysis results, and combined with the cost of each metal material, determine the suitable materials for each heat exchange section of the heat exchanger within the flue gas temperature range of 60-150℃, and form a heat exchanger material selection scheme.

6. The experimental method for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 5, characterized in that: In step S3, the counter-current heat exchange between flue gas and water satisfies the following: the flue gas gradually cools down along the heat exchange tube bundle a(402) / b(502) / c(602) / d(702), and the water gradually heats up along the heat exchange tube bundle d(702) / c(602) / b(502) / a(402). The high-temperature section of the flue gas and the high-temperature section of the water coincide at heat exchange tube bundle a(402).

7. The experimental method for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 5, characterized in that: In step S5, the condensate collected in the condensate collection tank is collected by the drain pipe and then transported to the sewage treatment system to avoid pollution caused by the direct discharge of acidic condensate.

8. The experimental method for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 5, characterized in that: In step S6, the variables in the multi-condition experiment include flue gas velocity, flue gas temperature, water flow rate, metal sheet wall temperature, and acid gas concentration. The adjustment range of each variable matches the actual operating conditions of the waste incineration plant.

9. The experimental method for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 5, characterized in that: In step S8, the heat exchanger material selection scheme should take into account both the corrosion resistance and cost economy of the material. 2205 stainless steel is selected in the low temperature corrosion high incidence range of 60-80℃, 316L stainless steel is selected in the range of 80-100℃, ND steel is selected in the range of 100-120℃, and carbon steel is selected in the range of 120-150℃.

10. The experimental method for material selection of a waste heat recovery heat exchanger for incineration flue gas according to claim 5, characterized in that: During the experiment, if the temperature of the low-temperature flue gas discharged from the heat exchanger body is too low, open the bypass electric valve to mix the bypass unheated flue gas with the low-temperature flue gas in the flue gas mixer (9), thereby increasing the flue gas emission temperature and preventing corrosion of the flue inside the chimney (11).

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