Oxygen-enriched combustion heating furnace system and heating method

Abstract

The invention discloses an oxygen-enriched combustion heating furnace system and a heating method, and the heating furnace system comprises a second heat exchanger which is used for heating normal-temperature air to preheated air through discharged flue gas; the first heat exchanger is used for heating the preheated air to heated air through high-temperature oxygen-deficient air; the preheating furnace is used for incompletely combusting fuel, oxygen-enriched gas and circulating flue gas to generate pre-combusted flue gas containing CO and heating the heated air to high-temperature air; the oxygen-permeable membrane reactor is provided with an oxygen-permeable membrane tube and is used for separating the high-temperature air into high-temperature oxygen-deficient air and oxygen, so that after the pre-combustion flue gas and the oxygen are completely combusted, the pre-combustion flue gas and the oxygen form oxygen-enriched gas; and the material heating furnace is used for combusting oxygen-enriched gas and fuel so as to generate high-temperature flue gas for heating the materials, and the high-temperature flue gas heats the materials to be cooled so as to form discharged flue gas and circulating flue gas. The device and the method are used for improving the heat efficiency and reducing the difficulty of pollutant treatment and CO2 capture.

Description

Technical Field

[0001] The present invention relates to the technical field of heating furnaces, in particular to an oxygen-enriched combustion heating furnace system and a heating method. Background Art

[0002] At present, most of the tubular heating furnaces in refineries use fuel and air contact combustion to heat the process medium, and the high-temperature flue gas is discharged after passing through the waste heat recovery system. During the heating process, the exhaust temperature of the flue gas is high, generally above 120°C, and a large amount of heat is wasted, making it difficult to improve the efficiency of the heating furnace; the direct contact combustion of fuel gas and air, at a flame temperature greater than 1200°C, will produce thermal NO x and fast-acting NO x The exhaust gas contains a large amount of NO x , resulting in serious pollutant emissions and high difficulty in pollutant control; the flue gas of traditional heating furnaces has extremely low CO2 concentration, and it consumes a lot of energy to concentrate and capture it. It is generally discharged directly into the atmosphere, and efficient capture of CO2 cannot be achieved. Summary of the Invention

[0003] The present invention aims to provide an oxygen-enriched combustion heating furnace system and a heating method for improving thermal efficiency and reducing the difficulty of pollutant treatment and CO2 capture.

[0004] In order to solve the above technical problems, the specific solution adopted by the present invention is: an oxygen-enriched combustion heating furnace system having:

[0005] The second heat exchanger heats the normal temperature air to preheated air through the exhaust gas;

[0006] The first heat exchanger raises the temperature of the preheated air to heated air through high-temperature oxygen-depleted air;

[0007] The preheating furnace provides incomplete combustion of fuel, oxygen-rich gas and circulating flue gas, produces pre-combustion flue gas containing CO and heats the heated air to high-temperature air;

[0008] The oxygen permeable membrane reactor has an oxygen permeable membrane tube that separates high-temperature air into high-temperature oxygen-depleted air and oxygen, which is used for the pre-combustion flue gas to be completely burned with oxygen and then form oxygen-rich gas with oxygen;

[0009] The material heating furnace is used to burn oxygen-rich gas and fuel to generate high-temperature flue gas for heating the material. The high-temperature flue gas heats the material and then cools it down to form exhaust flue gas and circulating flue gas.

[0010] Preferably, the oxygen permeable membrane reactor is of tube-sheet type, the operating temperature of the oxygen permeable membrane reactor is 400-1100°C, the pressure difference on both sides of the oxygen permeable membrane tube is 0-10 MPa, and the pressure inside the oxygen permeable membrane tube is not lower than the pressure outside the oxygen permeable membrane tube.

[0011] Preferably, the oxygen permeable membrane tube is a circular membrane tube with a diameter of 1-30 mm and a thickness of 0.1-6 mm. The spacing between the oxygen permeable membrane tubes is 0.5-4 times the diameter.

[0012] Preferably, the oxygen permeable membrane in the oxygen permeable membrane tube is a perovskite, fluorite-perovskite, fluorite-metal or perovskite-metal structure.

[0013] Preferably, the oxygen permeable membrane in the oxygen permeable membrane tube is a single-layer membrane or a multi-layer membrane.

[0014] Heating is performed using any of the above-mentioned oxygen-enriched combustion heating furnace systems.

[0015] Preferably, the temperature, pressure and flow rate of the air entering the oxygen permeable membrane reactor are controlled to adjust the oxygen concentration in the oxygen-rich gas.

[0016] Preferably, the volume concentration of oxygen in the oxygen-rich gas is adjusted to 0-80%.

[0017] Preferably, the volume concentration of oxygen in the oxygen-rich gas is adjusted to 25-30%.

[0018] Preferably, the oxygen-enriched gas entering the material heating furnace accounts for 10-100% of the total amount of the oxygen-enriched gas.

[0019] Preferably, the fuel entering the material heating furnace accounts for 0-90% of the total fuel.

[0020] Preferably, when the material heating temperature in the material heating furnace is lower than 500°C, all the fuel is passed into the preheating furnace, and a complete reaction is achieved in the oxygen permeable membrane reactor. All the high-temperature gas generated in the oxygen permeable membrane reactor is led out into the material heating furnace to heat the material.

[0021] Preferably, the circulating flue gas accounts for 80-95% of the total flue gas drawn out of the material heating furnace. Beneficial effects

[0022] First, the exhaust of the heating furnace system of the present invention is only oxygen-depleted air below 60°C. Compared with the flue gas emission temperature of 120°C of traditional heating furnaces, the exhaust temperature of the present invention is reduced by 60°C, thereby improving the thermal efficiency of the heating furnace by 3-4 percentage points, thereby significantly improving the thermal efficiency.

[0023] Second, the fuel in the present invention burns with oxygen-rich gas without contacting nitrogen in the air, thus generating no thermal NOx. x At the same time, after the water is separated by low-temperature flue gas condensation, CO2 can be directly collected and processed, so the process of the present invention can achieve no CO2, NO x Emissions are reduced to achieve environmentally friendly operation of the heating furnace.

[0024] Third, the flue gas generated by the present invention contains only CO2 and H2O. After the flue gas is condensed, CO2 with a concentration of more than 99% can be separated and can be directly collected and processed.

[0025] Fourth, the oxygen-enriched combustion system in the heating furnace of the present invention is simple, fast, and highly efficient. Conventional technologies such as cryogenic distillation, membrane separation, pressure swing adsorption, and chemical looping air separation are expensive and complex to produce pure oxygen. The present invention utilizes a simple oxygen-permeable membrane reactor to enrich oxygen, reducing operating costs by over 20% compared to existing oxygen production technologies. The oxygen-enriched combustion system in the heating furnace is simple, fast, and highly efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of an oxygen-enriched combustion heating furnace system of the present invention;

[0027] Figure 2 Schematic diagram of an oxygen-enriched heating furnace system with a heating temperature below 500° C. provided in this embodiment;

[0028] Markings in the figure: 1. Preheating furnace, 2. Oxygen permeable membrane reactor, 3. Material heating furnace, 4. Second heat exchanger, 5. First heat exchanger. DETAILED DESCRIPTION

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides an oxygen-enriched heating furnace system, which mainly includes a preheating furnace 1, an oxygen permeable membrane reactor 2, a material heating furnace 3, a second heat exchanger 4, and a first heat exchanger 5. The oxygen permeable membrane reactor 2 has an oxygen permeable membrane tube. The oxygen permeable membrane on the oxygen permeable membrane tube is a perovskite mixed conductor oxygen permeable membrane. The pressure difference across the oxygen permeable membrane tube is 1 MPa. The specific implementation process of this embodiment is as follows:

[0031] (1) 20°C normal temperature air enters the second heat exchanger 4 and exchanges heat with the 150-300°C exhaust gas to raise the temperature to 30-50°C to form preheated air. The preheated air enters the first heat exchanger 5 and exchanges heat with the 600-900°C high temperature oxygen-depleted air. After the temperature rises to 400-800°C, it forms heated air and enters the preheating furnace 1. It is further heated to 450-850°C high temperature air and enters the oxygen permeable membrane reactor 2. In the oxygen permeable membrane reactor 2, the oxygen in the high temperature air passes through the inner side of the oxygen permeable membrane tube and enters the outside of the tube. The 600-900°C high temperature oxygen-depleted air in the oxygen permeable membrane tube enters the first heat exchanger 5 and exchanges heat with the 30-50°C preheated air, becoming low temperature oxygen-depleted air at 40-60°C and then is discharged.

[0032] (2) 10-100% of the fuel enters the preheating furnace 1 and mixes with 0-90% of the 600-900℃ oxygen-enriched gas from the oxygen permeable membrane reactor 2 and the 150-300℃ circulating flue gas from the material heating furnace 3, undergoing incomplete combustion to generate pre-combustion flue gas containing CO to heat the high-temperature air in the furnace tube. The oxygen concentration in the oxygen-enriched gas can be adjusted by controlling the temperature, pressure, and flow rate of the air entering the oxygen permeable membrane reactor 2. The higher the air temperature, the greater the pressure, and the greater the flow rate, the faster the oxygen separation and transfer speed, and the higher the oxygen concentration. During operation, one, two, or three of these parameters can be adjusted to meet actual needs, and vice versa.

[0033] (3) After heating the air, the pre-combustion flue gas at 700-1000°C enters the oxygen permeable membrane reactor 2, reacts with the oxygen that permeates outside the oxygen permeable membrane tube, and is completely burned, providing heat for the oxygen migration of the oxygen permeable membrane reactor 2, and mixes with the oxygen to form an oxygen-rich gas at 600-900°C.

[0034] (4) 0-90% of the fuel enters the material heating furnace 3 and is mixed with 10-100% of the 600-900°C oxygen-rich gas coming out of the oxygen permeable membrane reactor 2 and fully burned to heat the material.

[0035] (5) The high-temperature flue gas generated by the combustion in the material heating furnace 3 is cooled to 150-300°C by the heating furnace material. 5-20% of the flue gas enters the preheating furnace 1 as circulating flue gas, and 80-95% of the flue gas enters the second heat exchanger 4 as exhaust flue gas. After heat exchange and cooling with the air, it becomes a low-temperature flue gas of 30-50°C, and CO2 is subsequently separated and collected.

[0036] Example 2

[0037] like Figure 2 As described above, this embodiment provides an oxygen-enriched heating furnace system with a heating temperature below 500°C. The material outlet temperature of the material heating furnace 3 is below 500°C. The oxygen permeable membrane is a perovskite mixed conductor oxygen permeable membrane, and the pressure difference across the oxygen permeable membrane tube is 1 MPa. The specific implementation process of this embodiment is as follows:

[0038] (1) 20℃ normal temperature air enters the second heat exchanger 4 and exchanges heat with 200℃ exhaust gas to raise its temperature to 40℃ to form preheated air. The preheated air enters the first heat exchanger 5 and exchanges heat with 750℃ high temperature oxygen-depleted air. After the temperature rises to 600℃, it forms heated air and enters the preheating furnace 1. The high temperature air further heated to 650℃ in the preheating furnace 1 enters the oxygen permeable membrane reactor 2. In the oxygen permeable membrane reactor 2, the oxygen in the high temperature air passes through the inside of the oxygen permeable membrane tube and enters the outside of the tube. The 750℃ high temperature oxygen-depleted air in the oxygen permeable membrane tube enters the first heat exchanger 5 and exchanges heat with the 40℃ preheated air, becoming low temperature oxygen-depleted air at 50℃ and then being discharged.

[0039] (2) The fuel enters the preheating furnace 1 and mixes with 10% of the 750℃ oxygen-rich gas and 200℃ circulating flue gas from the oxygen permeable membrane reactor 2, undergoing incomplete combustion to generate pre-combustion flue gas containing CO to heat the air in the furnace tube.

[0040] (3) After heating the air, the 850°C pre-combustion flue gas enters the oxygen permeable membrane reactor 2, reacts with the oxygen that has permeated outside the oxygen permeable membrane tube, and is completely burned, providing heat for the oxygen migration in the oxygen permeable membrane reactor 2, and mixes with the oxygen to form a 750°C high-temperature gas.

[0041] (4) The 750°C high-temperature gas coming out of the oxygen permeable membrane reactor 2 enters the material heating furnace 3 to heat the material.

[0042] (5) After the material in the high-temperature gas heating furnace is cooled, 10% of the 200°C flue gas enters the preheating furnace 1 as circulating flue gas, and 90% of the 200°C flue gas enters the second heat exchanger 4 as exhaust flue gas to exchange heat with air and cool down, turning into 40°C low-temperature flue gas for subsequent separation and collection of CO2.

Claims

1. An oxygen-enriched combustion heating furnace system, characterized in that: have: The second heat exchanger heats the normal temperature air to preheated air through the exhaust gas; The first heat exchanger raises the temperature of the preheated air to heated air through high-temperature oxygen-depleted air; The preheating furnace provides incomplete combustion of fuel, oxygen-rich gas and circulating flue gas, produces pre-combustion flue gas containing CO and heats the heated air to high-temperature air; The oxygen permeable membrane reactor has an oxygen permeable membrane tube that separates high-temperature air into high-temperature oxygen-depleted air and oxygen, which is used for the pre-combustion flue gas to be completely burned with oxygen and then form oxygen-rich gas with oxygen; The material heating furnace is used to burn oxygen-rich gas and fuel to generate high-temperature flue gas for heating the material. The high-temperature flue gas heats the material and then cools it down to form exhaust flue gas and circulating flue gas.

2. The oxygen-enriched combustion heating furnace system according to claim 1, characterized in that: The oxygen permeable membrane reactor is of tube-sheet type. The operating temperature of the oxygen permeable membrane reactor is 400-1100°C. The pressure difference on both sides of the oxygen permeable membrane tube is 0-10MPa. The pressure inside the oxygen permeable membrane tube is not lower than the pressure outside the oxygen permeable membrane tube.

3. The oxygen-enriched combustion heating furnace system according to claim 1, characterized in that: The oxygen permeable membrane tube is a circular tube membrane with a diameter of 1-30 mm and a thickness of 0.1-6 mm. The spacing between the oxygen permeable membrane tubes is 0.5-4 times the diameter.

4. The oxygen-enriched combustion heating furnace system according to claim 1, characterized in that: The oxygen permeable membrane in the oxygen permeable membrane tube is a perovskite, fluorite-perovskite, fluorite-metal or perovskite-metal structure.

5. The oxygen-enriched combustion heating furnace system according to claim 1, characterized in that: The oxygen permeable membrane in the oxygen permeable membrane tube is a single-layer membrane or a multi-layer membrane.

6. The method for heating a material by oxygen-enriched combustion according to claim 1, wherein: Heating is performed using any one of the oxygen-enriched combustion heating furnace systems described in claims 1-5.

7. The method for heating a material by oxygen-enriched combustion according to claim 6, wherein: The temperature, pressure and flow of the air entering the oxygen permeable membrane reactor are controlled to adjust the oxygen concentration in the oxygen-rich gas.

8. The method for heating a material by oxygen-enriched combustion according to claim 7, wherein: The volume concentration of oxygen in the oxygen-rich gas is adjusted to 0-80%.

9. The method for heating a material by oxygen-enriched combustion according to claim 7, wherein: The volume concentration of oxygen in the oxygen-rich gas is adjusted to 25-30%.

10. The method for heating a material by oxygen-enriched combustion according to claim 6, wherein: The oxygen-rich gas entering the material heating furnace accounts for 10-100% of the total oxygen-rich gas.

11. The method for heating a material by oxygen-enriched combustion according to claim 6, wherein: The fuel entering the material heating furnace accounts for 0-90% of the total fuel.

12. The method for heating a material by oxygen-enriched combustion according to claim 6, wherein: When the material heating temperature in the material heating furnace is lower than 500°C, all the fuel is passed into the preheating furnace to achieve complete reaction in the oxygen permeable membrane reactor, and all the high-temperature gas generated in the oxygen permeable membrane reactor is led out into the material heating furnace to heat the material.

13. The method for heating a material by oxygen-enriched combustion according to claim 6, wherein: The circulating flue gas accounts for 80-95% of the total flue gas discharged from the material heating furnace.

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