Built-in heat exchanger, RTO and method for treating organic waste liquid and organic waste gas

Abstract

The present invention discloses a built-in heat exchanger, RTO and a method for treating organic waste liquid and organic waste gas, comprising a frame-type heat exchanger support with a fluid inlet, a return pipe with a fluid outlet and a fluid heat exchange pipeline, the return pipe is arranged in a square frame shape below the top of the heat exchanger support, the heat exchange pipeline is arranged in a mirror image in the width direction of the heat exchanger support and arranged along its length direction, the heat exchange pipeline is arranged in a serpentine shape with two ends of the curved section with a zigzag structure with alternating directions, including a first vertical section, a second inclined section and a third horizontal section connected in sequence, the length of the second inclined section decreases from the end to the center along the width direction of the heat exchanger support, and the two ends of the heat exchange pipeline are the first vertical sections with the openings flush upward and are respectively connected in the length direction of the heat exchanger support and the return pipe. A multi-layer stacking structure is adopted, and each layer of heat exchange tubes adopts multiple circulation channels to increase the heat exchange area and effectively absorb the shrinkage of thermal expansion and contraction, forming three different spatial structures.

Description

Technical Field

[0001] The invention belongs to the technical field of waste liquid and waste gas purification treatment, and relates to a built-in heat exchanger, an RTO and a method for treating organic waste liquid and organic waste gas. Background Art

[0002] RTO (Regenerative Thermal Oxidizer) is an industrial waste gas treatment equipment used to treat volatile organic compounds (VOCs) and other harmful gases. The waste gas is first heated to a temperature close to the thermal oxidation temperature by a thermal storage body, and then enters the combustion chamber for thermal oxidation. During this process, the organic matter is basically converted into oxygen and water and releases heat. The purified gas passes through another thermal storage body, the temperature drops, and it is discharged after meeting the emission standards. If the heat released is greater than the heat required by the RTO itself, waste heat recovery can be performed.

[0003] VOCs contain nitrogen or nitrogen oxides, and during their decomposition process, the high temperature causes N2 and O2 in the air to react to generate NOx. If the fuel supply is unstable or the temperature control during the combustion process is inaccurate, it may cause NOx to exceed the standard. NOx will pollute the atmosphere and is one of the most important controlled pollutants in existing environmental governance.

[0004] Conventional RTO removes nitrogen oxides by setting up post-treatment, such as SCR denitration, to reduce the concentration of nitrogen oxides in the exhaust gas. Or use a scrubber as a post-treatment measure to remove nitrogen oxides through chemical reactions. Although this method can effectively remove nitrogen oxides from exhaust gas, it requires additional equipment and operating steps, which increases the complexity of the system and investment and operating costs.

[0005] Therefore, an RTO with a specially structured built-in heat exchanger is needed to treat VOCs. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a built-in heat exchanger, an RTO, and a method for treating organic waste liquid and organic waste gas. The heat exchanger tubes of the present invention adopt a multi-layer stacking structure, and each layer of heat exchange tubes adopts a multi-circulation flow channel structure, which not only increases the heat exchange area, but also effectively absorbs the shrinkage caused by thermal expansion and contraction. At the same time, three different spatial structures are formed by using the heat exchanger tubes. The process method based on the heat exchanger thermal storage oxidation furnace not only treats organic waste liquid and organic waste gas, but also eliminates nitrogen oxides and recovers heat energy by a three-stage oxidation method.

[0007] The technical solution provided by the present invention is as follows:

[0008] In the first aspect, the present invention provides a built-in heat exchanger, comprising a frame-type heat exchanger bracket with a fluid inlet, a return pipe with a fluid outlet, and a fluid heat exchange pipeline. The return pipe is arranged in a square frame shape below the top of the heat exchanger bracket, the fluid heat exchange pipeline is mirrored in the width direction of the heat exchanger bracket and a plurality of fluid heat exchange pipelines are arranged along the length direction of the heat exchanger bracket, the fluid heat exchange pipeline is arranged in a serpentine shape with curved sections with alternating directions, and both ends of the curved sections are connected to a zigzag structure, the zigzag structure includes a first vertical section, a second inclined section, and a third horizontal section connected in sequence, the length of the second inclined section gradually decreases from the end to the center along the width direction of the heat exchanger bracket, and the two ends of the fluid heat exchange pipeline are first vertical sections with openings flush upward and are respectively connected in the length direction of the heat exchanger bracket and the return pipe.

[0009] Furthermore, a plurality of U-shaped flow channel supports corresponding to the curved sections above the fluid heat exchange pipelines are connected between the width sides of the heat exchanger support, and the U-shaped flow channel supports support a plurality of fluid heat exchange pipelines arranged along the length direction of the heat exchanger support.

[0010] Furthermore, the heat exchanger support includes a first horizontal tube located at the top and a second horizontal tube located at the bottom arranged along the width direction, a first vertical tube located at the top and a second vertical tube located at the bottom arranged along the length direction, and a vertical tube connecting the horizontal tubes and the vertical tubes, and three of the first horizontal tubes and three of the second horizontal tubes are provided. A fluid inlet is provided in the middle position of the first horizontal tube located on the front side, and a fluid outlet is provided on the return pipe parallel to the middle position of the first horizontal tube on the front side, which is perpendicular to the fluid inlet and opens downward.

[0011] Furthermore, the fluid inlet and the fluid outlet are interchangeable interfaces, and both the fluid inlet and the fluid outlet can input fluid medium or output fluid medium.

[0012] Furthermore, the fluid medium is any one of water, air or heat transfer oil.

[0013] Furthermore, the multiple first vertical sections and the multiple first horizontal sections of the fluid heat exchange pipeline are stacked to form a right-angled trapezoid, and the multiple first inclined sections are stacked to form an isosceles trapezoid.

[0014] Furthermore, the heat exchanger bracket and the flow channel bracket are both hollow pipe structures made of high temperature resistant materials.

[0015] In a second aspect, the present invention provides an RTO with the above-mentioned built-in heat exchanger, comprising a combustion chamber and three heat storage chambers connected to the combustion chamber, a first built-in heat exchanger and a second built-in heat exchanger are respectively installed in the combustion chambers on both sides of the middle heat storage chamber, a first burner is installed in the middle of the outer plate of the first built-in heat exchanger, and the fluid heat exchange pipeline of the first built-in heat exchanger encloses to form an oxygen-deficient combustion chamber, a second burner is installed at the bottom of the outer plate of the second built-in heat exchanger, and the fluid heat exchange pipeline of the second built-in heat exchanger encloses to form a mixing zone of cooled exhaust gas, and the combustion chambers outside the first built-in heat exchanger and the second built-in heat exchanger form an oxygen-rich environment.

[0016] In a third aspect, the present invention provides a method for treating organic waste liquid and organic waste gas using the above-mentioned RTO with a built-in heat exchanger, comprising the following steps:

[0017] The organic waste liquid or nitrogen-containing organic waste gas is sprayed into the oxygen-deficient combustion chamber through the first burner for the first stage of oxygen-deficient combustion to generate tail gas containing CO2, CO, N2 and H2O;

[0018] The exhaust gas after combustion passes through the heat exchange section of the first built-in heat exchanger for the second stage of cooling. The fluid medium in the heat exchanger absorbs the excess heat in the exhaust gas, so that the exhaust gas temperature is reduced from 1050~1350℃ to 760~950℃;

[0019] The cooled tail gas flows into the combustion chamber and undergoes the third stage of thermal oxidation in an oxygen-rich environment. CO in the tail gas further reacts with O2 to generate CO2, obtaining purified tail gas. Heat is released at the same time to increase the temperature of the combustion chamber. The purified tail gas enters the heat storage chamber for heat recovery and is then discharged from the flue gas outlet to the heat storage chamber oxidation furnace.

[0020] and / or,

[0021] The nitrogen-free organic waste gas is sprayed into the combustion chamber through the second burner for thermal oxidation in an oxygen-rich environment to generate CO2 and H2O, obtain purified tail gas, and release a large amount of heat;

[0022] The purified exhaust gas is cooled in the heat exchange section of the second built-in heat exchanger, and the excess heat in the exhaust gas is absorbed by the fluid medium in the heat exchanger, so that the exhaust gas temperature is reduced to 200~250℃ before entering the mixing zone; wherein, the cooled exhaust gas is transported into the combustion chamber for heat absorption through the air duct between the combustion fan on the second burner and the mixing zone of the second built-in heat exchanger, thereby promoting self-circulation of the combustion chamber.

[0023] Furthermore, the third thermal oxidation stage also includes temperature control, and the control includes:

[0024] When the temperature of the purified exhaust gas is lower than 800℃, the second burner is activated to raise the temperature to 850℃; when the temperature of the purified exhaust gas is higher than 950℃, the blower of the second burner is activated to use the cold air outside the furnace to cool down the RTO combustion chamber, and at the same time, the RTO thermal bypass is opened for exhaust to maintain the balance of the RTO inlet and outlet gas volumes.

[0025] Beneficial effects:

[0026] The heat exchanger tube of the present invention adopts a multi-layer stacking structure, and each layer of heat exchange tube adopts a multi-circulation flow channel structure, which not only increases the heat exchange area, but also effectively absorbs the shrinkage caused by thermal expansion and contraction. At the same time, three different spatial structures are formed by using the heat exchanger tube. The heat exchanger bracket and the flow channel bracket can provide support and suspension for the fluid heat exchange pipeline, and form a heat exchanger as a whole with the fluid heat exchange pipeline, which can withstand the high temperature environment inside the RTO while having higher heat exchange efficiency. All supporting structures use round tubes to maintain structural strength, and the tubes are filled with cooling medium. The cooling medium is the same as the cooling medium required by the system, which not only plays a role in cooling protection, but also increases the heat exchange area of ​​the heat exchanger. The inlet and outlet of the cooling medium of the heat exchanger can be replaced with each other, thereby forming different temperature gradients in three areas, thereby meeting different application requirements.

[0027] The present invention divides the RTO combustion chamber into three relatively independent spaces by arranging a heat exchanger with a special structure inside the RTO, thereby creating sufficient conditions for subsequent applications. By arranging an external burner at the heat exchanger near the waste liquid inlet on the RTO, the combustion chamber where the heat exchanger is located becomes an excellent combustion cavity, which not only creates an oxygen-deficient environment for the combustion of the waste liquid, causing it to incompletely burn to generate CO and inhibit the formation of fuel-type nitrogen oxides, but also reduces the flame temperature and inhibits the formation of thermal nitrogen oxides.

[0028] The present invention can adapt to the needs of organic waste liquid combustion, high-concentration organic waste gas oxidation and high-LEL organic waste gas treatment by switching the forward and reverse flow channels; the RTO heat exchanger sets water, air or heat transfer oil as the cooling medium, converts excess heat into hot water, high-temperature steam or high-temperature heat transfer oil and transports it to the corresponding heat-using equipment, thereby reducing energy consumption.

[0029] The process method of the present invention not only treats organic waste liquid and organic waste gas, but also eliminates nitrogen oxides and recovers heat energy by adopting a three-stage oxidation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the built-in special structure heat exchanger in an embodiment of the present invention.

[0031] Figure 2 It is a schematic diagram of the fluid heat exchange pipeline in the built-in special structure heat exchanger in the embodiment of the present invention.

[0032] Figure 3 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0033] Figure 4 Schematic diagram of the overall structure for treating VOCs in an embodiment of the present invention.

[0034] Explanation of the accompanying drawings: 11. First built-in heat exchanger; 12. Second built-in heat exchanger; 111. Heat exchanger bracket; 112. Flow channel bracket; 113. Fluid heat exchange pipeline; 114. Reflux pipe; 2. First burner; 3. Second burner; 4. Oxygen-deficient combustion chamber; 5. High temperature zone; 6. Mixing zone; 7. Heat exchange section; A. Fluid inlet; B. Fluid outlet; C. Exhaust gas inlet; D. Exhaust gas outlet; L. Middle of outer plate; M. Bottom of outer plate. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0038] Example 1

[0039] An embodiment of the present invention provides a built-in heat exchanger, comprising a frame-type heat exchanger support 111 with a fluid inlet A, a return pipe 114 with a fluid outlet B, and a fluid heat exchange pipeline 113. The return pipe 114 is in a square frame shape and is arranged below the top of the heat exchanger support 111. The fluid heat exchange pipeline 113 is distributed in a mirror-symmetrical manner in the width direction of the heat exchanger support 111, and a plurality of fluid heat exchange pipelines 113 are arranged along the length direction of the heat exchanger support 111. The fluid heat exchange pipeline 113 is arranged in a serpentine shape with curved sections with alternating directions. Both ends of the curved sections are connected to a zigzag structure. The zigzag structure includes a first vertical section, a second inclined section, and a third horizontal section connected in sequence. The length of the second inclined section gradually decreases from the end to the center along the width direction of the heat exchanger support 111. Both ends of the fluid heat exchange pipeline 113 are first vertical sections with openings flush upward and are respectively connected in the length direction of the heat exchanger support 111 and the return pipe 114.

[0040] In this embodiment, a plurality of U-shaped flow channel supports 112 corresponding to the curved sections above the fluid heat exchange pipelines 113 are connected between the width sides of the heat exchanger support 111, and the U-shaped flow channel supports 112 support a plurality of fluid heat exchange pipelines 113 arranged along the length direction of the heat exchanger support 111.

[0041] Specifically, the first built-in heat exchanger 11 and the second built-in heat exchanger 12 both include a heat exchanger bracket 111 and a fluid heat exchange pipeline 113. The heat exchanger bracket 111 adopts a full-channel structure. The overall bracket is made of hollow pipelines welded together, using high-temperature resistant materials and having fluid inside. In addition, a flow channel bracket 112 is provided on the heat exchanger bracket 111. The flow channel bracket 112 is also a hollow pipeline structure made of high-temperature resistant materials, which supports and suspends the fluid heat exchange pipeline 113. The heat exchanger bracket 111, the fluid heat exchange pipeline 113 and the flow channel bracket 112 together constitute the heat exchanger. As a whole, the fluid heat exchange pipeline 113 is a serpentine loop with a zigzag structure, and both ends of the fluid heat exchange pipeline 113 are provided with fluid openings opening upward (that is, both ends of the fluid heat exchange pipeline 113 are the first vertical sections opening upward and flush), the fluid openings near the two sides of the heat exchanger bracket 111 are connected with the pipelines on both sides of the length direction of the heat exchanger bracket 111, and the fluid openings near the inside of the heat exchanger bracket 111 are connected with both sides of the length direction of the return pipe 114, and the return pipe 114 is also supported by the fluid heat exchange pipeline 113 below the top of the heat exchanger bracket 111.

[0042] In this embodiment, the heat exchanger support 111 includes a first horizontal tube located at the top and a second horizontal tube located at the bottom arranged along the width direction, a first vertical tube located at the top and a second vertical tube located at the bottom arranged along the length direction, and vertical tubes connecting the horizontal tubes and the vertical tubes. There are three of each of the first horizontal tubes and the second horizontal tubes. A fluid inlet A is provided in the middle position of the first horizontal tube located on the front side, and the return pipe 114 is parallel to the middle position of the first horizontal tube on the front side and is provided with a fluid outlet B that is perpendicular to the fluid inlet A and opens downward.

[0043] In this embodiment, the fluid inlet A and the fluid outlet B are interchangeable interfaces, and both the fluid inlet A and the fluid outlet B can input or output fluid media, and the forward and reverse flow channels are switched, thereby increasing the heat exchange area and improving the heat exchange efficiency.

[0044] In this embodiment, the fluid medium is any one of water, air or heat transfer oil.

[0045] In this embodiment, the multiple first vertical sections and the multiple first horizontal sections of the fluid heat exchange pipeline 113 are stacked to form a right-angled trapezoid, and the multiple first inclined sections are stacked to form an isosceles trapezoid.

[0046] Example 2

[0047] An embodiment of the present invention provides an RTO with the built-in heat exchanger described in Example 1, including a combustion chamber and three heat storage chambers connected to the combustion chamber, a first built-in heat exchanger 11 and a second built-in heat exchanger 12 are respectively installed in the combustion chambers on both sides of the middle heat storage chamber, a first burner 2 is installed in the middle L of the outer plate of the first built-in heat exchanger 11, and the fluid heat exchange pipeline of the first built-in heat exchanger 11 encloses to form an oxygen-deficient combustion chamber 4, a second burner 3 is installed at the bottom M of the outer plate of the second built-in heat exchanger 12, and the fluid heat exchange pipeline of the second built-in heat exchanger 12 encloses to form a mixing zone 6 of the cooled exhaust gas, and the combustion chambers outside the first built-in heat exchanger 11 and the second built-in heat exchanger 12 form an oxygen-rich environment, i.e., a high temperature zone 5.

[0048] Example 3

[0049] The present invention also provides a method for treating organic waste liquid and organic waste gas by using an RTO with a built-in heat exchanger as described in Example 2, comprising the following steps:

[0050] The organic waste liquid or nitrogen-containing organic waste gas is sprayed into the oxygen-deficient combustion chamber 4 through the first burner 2 for the first stage of oxygen-deficient combustion to generate tail gas containing CO2, CO, N2 and H2O;

[0051] The exhaust gas after combustion passes through the heat exchange section 7 of the first built-in heat exchanger 11 for the second stage of cooling, and the fluid medium in the heat exchanger absorbs the excess heat in the exhaust gas, so that the exhaust gas temperature is reduced from 1050~1350℃ to 760~950℃;

[0052] The cooled tail gas flows into the oxygen-rich environment of the combustion chamber, i.e., the high temperature zone 5, for the third stage of thermal oxidation. CO in the tail gas further reacts with O2 to generate CO2, thereby obtaining purified tail gas. Meanwhile, heat is released to increase the temperature of the combustion chamber. The purified tail gas enters the heat storage chamber for heat recovery and is then discharged from the flue gas outlet to the heat storage chamber oxidation furnace.

[0053] and / or,

[0054] The nitrogen-free organic waste gas is sprayed into the oxygen-rich environment of the combustion chamber, i.e., the high-temperature zone 5, through the second burner 3 for thermal oxidation to generate CO2 and H2O, obtain purified tail gas, and release a large amount of heat;

[0055] The purified exhaust gas is cooled in the heat exchange section 7 of the second built-in heat exchanger 12, and the excess heat in the exhaust gas is absorbed by the fluid medium in the heat exchanger, so that the exhaust gas temperature is reduced to 200~250℃ before entering the mixing zone 6; wherein, the cooled exhaust gas is transported into the combustion chamber for heat absorption through the air duct between the combustion fan on the second burner 3 and the mixing zone 6 of the second built-in heat exchanger 12, thereby promoting self-circulation of the combustion chamber.

[0056] In this embodiment, the third thermal oxidation stage also includes temperature control, and the control includes:

[0057] When the temperature of the purified exhaust gas is lower than 800°C, the second burner 3 is activated to raise the temperature to 850°C; when the temperature of the purified exhaust gas is higher than 950°C, the blower of the second burner 3 is activated to use the cold air outside the furnace to cool the RTO combustion chamber, and at the same time, the RTO thermal bypass is opened for exhaust to maintain the balance of the RTO inlet and outlet gas volumes.

[0058] Specific:

[0059] 1. Process for treating organic waste liquid and nitrogen-containing organic waste gas

[0060] a. in Figure 3 The first burner 2 is installed at the middle L of the outer plate of the first built-in heat exchanger 11. The organic waste liquid or nitrogen-containing organic waste gas is sprayed into the oxygen-deficient combustion chamber 4 of the first built-in heat exchanger 11 through the first burner 2 for the first stage of oxygen-deficient combustion to generate tail gas containing CO2, CO, N2 and H2O;

[0061] b. The exhaust gas after combustion passes through the heat exchange section 7 of the first built-in heat exchanger 11 for the second stage of cooling, and the excess heat in the exhaust gas is absorbed by the fluid medium in the heat exchanger to reduce the exhaust gas temperature to the required temperature (the temperature after combustion meets the regulatory requirements and the physical and chemical requirements of waste treatment, with a maximum temperature of 1350°C. The lowered temperature meets the operating requirements of the RTO, generally not less than 760°C);

[0062] c. The cooled tail gas flows into the combustion chamber in an oxygen-rich environment, i.e., the high temperature zone 5, for the third stage of thermal oxidation. CO in the tail gas further reacts with O2 to generate CO2, thereby obtaining purified tail gas. Heat is released at the same time, thereby increasing the temperature of the RTO combustion chamber. The purified tail gas enters the RTO heat storage body for heat recovery and is then discharged from the RTO.

[0063] d. in Figure 4 The second burner 3 is installed at the bottom M of the outer plate of the second built-in heat exchanger 12. If the temperature of the purified exhaust gas is lower than 800°C, the second burner 3 is enabled to raise the temperature to 850°C; if the temperature of the purified exhaust gas is higher than 950°C, only the blower of the second burner 3 is enabled to use the cold air outside the furnace to cool down the RTO combustion chamber, and at the same time, the heat bypass of the RTO is opened for exhaust to maintain the balance of the RTO inlet and outlet air volumes.

[0064] 2. Process for treating organic waste gas

[0065] a. Pass nitrogen-free organic waste gas through Figure 4 The second burner 3 at the bottom M of the outer plate sprays into the combustion chamber of the RTO, i.e., the high temperature zone 5, for sufficient high temperature thermal oxidation (flame is not necessary at this time), generating CO2 and H2O and releasing a large amount of heat;

[0066] b. The purified high-temperature exhaust gas passes through the second built-in heat exchanger 12 for waste heat recovery. The fluid medium in the second built-in heat exchanger 12 absorbs the excess heat in the exhaust gas, so that the exhaust gas temperature is reduced to the required temperature, generally not less than 200°C;

[0067] c. Install an air duct. Figure 4 The combustion-supporting fan of the second burner 3 at the outer plate bottom M of the second built-in heat exchanger 12 and Figure 4 The two mixing zones are connected, and the combustion-supporting fan is used to transport the clean exhaust gas that has been heat recovered entering the mixing zone 6 to the high-temperature thermal oxidation zone of the RTO combustion chamber for cooling, thereby facilitating the high-temperature exhaust gas after thermal oxidation to flow to the mixing zone 6 of the second built-in heat exchanger 12, while preventing overheating in the high-temperature zone.

[0068] In the RTO system, the main induced draft fan blows in the waste gas to be treated through the waste gas inlet C. The lower box of the RTO is equipped with a switching valve to control the switching of the waste gas. The switching valve controls the flow direction of the waste gas to achieve the periodic switching of the waste gas. The switching valve switches the blown waste gas to the heat storage chamber, which preheats it. The preheated waste gas enters the RTO combustion chamber for combustion and decomposition. When the combustion process is completed, the switching valve switches to allow new waste gas to enter. At the same time, the negative pressure generated by the main induced draft fan and the rear induced draft fan is used to discharge the treated purified gas from the waste gas outlet D.

[0069] 1. Removal of nitrogen oxides

[0070] When the RTO equipment is working, three working stages are set.

[0071] First stage: oxygen-deficient combustion. By adjusting the ratio of burner fuel and air in the combustion chamber inside the heat exchanger, oxygen-deficient combustion is formed. In a high-temperature environment, when the oxygen supply is insufficient, the fuel cannot be fully burned, a large amount of CO is generated, and heat is released. CO acts as a reducing agent to reduce nitrogen oxides to N2.

[0072] Stage 2: Cooling. Since the CO generated in the first stage of combustion cannot be discharged and needs to be converted into CO2, oxygen supplementation is required at this time. The temperature condition for CO to react with oxygen to generate CO2 is below 950°C, and to prevent N2 and O2 from reacting to generate thermal NOx during oxygen supplementation, the exhaust gas temperature needs to be reduced to below 950°C. Setting a heat exchanger in the RTO combustion chamber plays this role. The heat exchanger uses water, air or thermal oil as the heat exchange medium, so that the high-temperature flue gas passes through the heat exchanger for cooling, and transfers the excess heat to the low-temperature medium, thereby solving the heat resistance problem in the combustion chamber. In addition, the built-in heat exchanger is configured with multiple flow channels, cyclic and repeated heat exchange, and has high heat exchange efficiency.

[0073] The third stage: oxygen supplementation. The high-temperature flue gas generated by the first stage combustion is then converted to below 950°C through the built-in heat exchanger and enters the RTO combustion chamber. The oxygen concentration in the RTO combustion chamber is greater than 15%, which is an oxygen-rich environment. Under this temperature condition, the CO generated by the first stage oxygen-deficient combustion reacts with the O2 in the RTO box to generate CO2, which is then discharged.

[0074] In the above process, nitrogen oxides produced during combustion are converted into N2 and H2O, and CO is converted into CO2 and discharged.

[0075] 2. Heat recovery

[0076] In addition to effectively removing nitrogen oxides, the present invention also converts the high-temperature heat energy generated during the RTO exhaust gas treatment process into recyclable excess heat energy through a heat exchanger that uses water, air or heat transfer oil as a medium, thereby improving the energy efficiency of the equipment.

[0077] During operation, the heat exchange medium enters the heat exchanger from the fluid inlet, flows along the fluid heat exchange pipeline to cool down, and then is output from the fluid outlet. In this process, the medium such as water, air or heat transfer oil is converted from low temperature to high temperature. In addition, the excess heat is converted into high-temperature hot water through the high-temperature flue gas in the RTO cavity and stored in the hot water tank, and then the hot water is sent to the heat-using equipment through the water circulation system; or the excess heat is converted into high-pressure steam, which can be connected in parallel with the manufacturer's original steam boiler or municipal steam, and then transported to the corresponding heat-using equipment; or the excess heat is converted into high-temperature heat transfer oil, which can be used for self-heating or connected in series with the user's original heat transfer oil boiler and pipeline. This allows the high-temperature flue gas during the operation of the RTO to be effectively recycled.

Claims

1. A built-in heat exchanger, characterized in that: It includes a frame-type heat exchanger bracket with a fluid inlet, a return pipe with a fluid outlet and a fluid heat exchange pipeline. The return pipe is arranged in a square frame shape below the top of the heat exchanger bracket. The fluid heat exchange pipeline is mirrored in the width direction of the heat exchanger bracket and is arranged in a plurality of length directions of the heat exchanger bracket. The fluid heat exchange pipeline is arranged in a serpentine shape with curved sections with alternating directions. Both ends of the curved sections are connected to a zigzag structure. The zigzag structure includes a first vertical section, a second inclined section and a third horizontal section connected in sequence. The length of the second inclined section gradually decreases from the end to the center along the width direction of the heat exchanger bracket. Both ends of the fluid heat exchange pipeline are first vertical sections with openings flush upward and are respectively connected in the length direction of the heat exchanger bracket and the return pipe.

2. The built-in heat exchanger according to claim 1, characterized in that: A plurality of U-shaped flow channel supports corresponding to the curved sections above the fluid heat exchange pipelines are connected between the width sides of the heat exchanger support, and the U-shaped flow channel supports support a plurality of fluid heat exchange pipelines arranged along the length direction of the heat exchanger support.

3. The built-in heat exchanger according to claim 1, characterized in that: The heat exchanger support includes a first horizontal tube located at the top and a second horizontal tube located at the bottom arranged along the width direction, a first vertical tube located at the top and a second vertical tube located at the bottom arranged along the length direction, and vertical tubes connecting the horizontal tubes and the vertical tubes. There are three first horizontal tubes and three second horizontal tubes. A fluid inlet is provided in the middle position of the first horizontal tube located on the front side, and the return pipe is parallel to the middle position of the first horizontal tube on the front side and has a fluid outlet that is perpendicular to the fluid inlet and opens downward.

4. The built-in heat exchanger according to claim 3, characterized in that: The fluid inlet and the fluid outlet are interchangeable interfaces, and both the fluid inlet and the fluid outlet can input fluid medium or output fluid medium.

5. The built-in heat exchanger according to claim 4, characterized in that: The fluid medium is any one of water, air or heat transfer oil.

6. The built-in heat exchanger according to claim 1, characterized in that: The plurality of first vertical sections and the plurality of first horizontal sections of the fluid heat exchange pipeline are stacked to form a right-angled trapezoid, and the plurality of first inclined sections are stacked to form an isosceles trapezoid.

7. The built-in heat exchanger according to claim 2, characterized in that: The heat exchanger bracket and the flow channel bracket are both hollow pipe structures made of high temperature resistant materials.

8. An RTO with a built-in heat exchanger according to any one of claims 1 to 7, characterized in that: It includes a combustion chamber and three heat storage chambers connected to the combustion chamber. A first built-in heat exchanger and a second built-in heat exchanger are respectively installed in the combustion chambers on both sides of the middle heat storage chamber. A first burner is installed in the middle of the outer plate of the first built-in heat exchanger, and the fluid heat exchange pipeline of the first built-in heat exchanger encloses an oxygen-deficient combustion chamber. A second burner is installed at the bottom of the outer plate of the second built-in heat exchanger, and the fluid heat exchange pipeline of the second built-in heat exchanger encloses a mixing zone for cooled exhaust gas. The combustion chambers outside the first built-in heat exchanger and the second built-in heat exchanger form an oxygen-rich environment.

9. A method for treating organic waste liquid and organic waste gas based on the RTO with a built-in heat exchanger according to claim 8, characterized in that: The following steps are involved: The organic waste liquid or nitrogen-containing organic waste gas is sprayed into the oxygen-deficient combustion chamber through the first burner for the first stage of oxygen-deficient combustion to generate tail gas containing CO2, CO, N2 and H2O; The exhaust gas after combustion passes through the heat exchange section of the first built-in heat exchanger for the second stage of cooling. The fluid medium in the heat exchanger absorbs the excess heat in the exhaust gas, so that the exhaust gas temperature is reduced from 1050~1350℃ to 760~950℃; The cooled tail gas flows into the combustion chamber and undergoes the third stage of thermal oxidation in an oxygen-rich environment. CO in the tail gas further reacts with O2 to generate CO2, obtaining purified tail gas. Heat is released at the same time to increase the temperature of the combustion chamber. The purified tail gas enters the heat storage chamber for heat recovery and is then discharged from the flue gas outlet to the heat storage chamber oxidation furnace. and / or, The nitrogen-free organic waste gas is sprayed into the combustion chamber through the second burner for thermal oxidation in an oxygen-rich environment to generate CO2 and H2O, obtain purified tail gas, and release a large amount of heat; The purified exhaust gas is cooled in the heat exchange section of the second built-in heat exchanger, and the excess heat in the exhaust gas is absorbed by the fluid medium in the heat exchanger, so that the exhaust gas temperature is reduced to 200~250℃ before entering the mixing zone; wherein, the cooled exhaust gas is transported into the combustion chamber for heat absorption through the air duct between the combustion fan on the second burner and the mixing zone of the second built-in heat exchanger, thereby promoting self-circulation of the combustion chamber.

10. The method for treating organic waste liquid and organic waste gas by using an RTO with a built-in heat exchanger according to claim 9, characterized in that: The third thermal oxidation stage also includes temperature control, which includes: When the temperature of the purified exhaust gas is lower than 800℃, the second burner is activated to raise the temperature to 850℃; when the temperature of the purified exhaust gas is higher than 950℃, the blower of the second burner is activated to use the cold air outside the furnace to cool down the RTO combustion chamber, and at the same time, the RTO thermal bypass is opened for exhaust to maintain the balance of the RTO inlet and outlet gas volumes.

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