Low-carbon low-nitrogen industrial heating system and method

Abstract

The invention belongs to the technical field of industrial heating in the petrochemical industry, and discloses a low-carbon low-nitrogen industrial heating system and method. The system comprises an industrial furnace, a fossil fuel combustor and a low-carbon fuel combustor. The fossil fuel burner is arranged at the bottom and / or the side wall of the industrial furnace; the fossil fuel combustor is provided with an air side inlet and a fossil fuel side inlet; the industrial furnace is provided with an air inlet and a top flue gas outlet; the low-carbon fuel burner is provided with a gas inlet and a gas outlet; the air inlet is connected with an air inlet pipeline and a low-carbon fuel pipeline; the air outlet is connected with the air side inlet and / or is connected with an air inlet of the industrial furnace; the fossil fuel side inlet is connected with a fossil fuel pipeline; and a top flue gas outlet of the industrial furnace is connected to a chimney through a flue gas pipeline. The main body structure of an industrial heating system is not changed, the system adapts to low-carbon fuel combustion characteristics and supply fluctuation, emission of carbon dioxide and nitrogen oxide is reduced, and high-quality development of the petroleum and petrochemical industry is supported.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial heating in the petrochemical industry, and more specifically, relates to a low-carbon and low-nitrogen industrial heating system and method. Background Art

[0002] Industrial heating systems are important systems in the petrochemical industry, mainly industrial furnace systems. In devices and units such as atmospheric and vacuum distillation, hydrogenation, reforming, aromatics, ethylene cracking, environmental incineration, and power boilers, industrial furnace systems are required to provide energy for heating materials or reactions and maintain temperature. According to the type of device, the energy consumption of industrial furnaces can account for 40% - 90% of the device energy consumption. Existing industrial heating systems heat by burning fossil fuels to generate flames and high-temperature gases. During this process, a large amount of flue gas is generated from the combustion of fossil fuels, among which more than 10% (wt) of the components are carbon dioxide, and there is also nitrogen oxides, a major air pollutant. The generation of nitrogen oxides is directly related to the combustion temperature and oxygen concentration. Therefore, industrial heating systems are concentrated emission sources of carbon dioxide and nitrogen oxides in petrochemical enterprises and are difficult points in nitrogen oxides emission reduction. How to reduce carbon dioxide and nitrogen oxides emissions is a key task in current industrial heating technology research.

[0003] New energy sources such as green hydrogen and green ammonia produced from resources such as light, wind, water, and nuclear, which have low carbon dioxide emissions, and biomass energy with net-zero carbon emissions throughout the life cycle provide a technical approach to reducing carbon dioxide emissions in industrial heating systems. Especially green hydrogen, as an energy storage and peak-shaving carrier, is very suitable as an industrial heating fuel. There is no carbon dioxide generated during the heating process, and it can save intermediate energy losses in processes such as green hydrogen power generation, and has good application prospects in carbon reduction. Related technical research mainly focuses on achieving low-carbon combustion by blending green hydrogen, green ammonia, etc. into fossil fuels. Although this method reduces carbon emissions to a certain extent, due to the relatively fast combustion speed of hydrogen and the relatively high temperature required for ammonia combustion, after mixing with fossil fuels, it has high requirements for burners and is difficult to adapt to the ratio fluctuations of low-carbon fuels and fossil fuels, and problems such as flameout, burner head burning, and nitrogen oxides exceeding the standard are likely to occur. Moreover, solid-phase biomass fuels without secondary processing cannot be mixed with fossil fuels, and the operation flexibility, fuel adaptability, and environmental protection performance of heating systems are greatly affected.

[0004] Therefore, it is necessary to provide a new low-carbon and low-nitrogen industrial heating system and method. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art, adapt to the current technology and energy supply level, and provide a low-carbon and low-nitrogen industrial heating system and method. The present invention does not change the main structure of the industrial heating system, and adapts to the combustion characteristics and supply fluctuations of low-carbon fuels, reducing carbon dioxide and nitrogen oxides emissions, which is beneficial to supporting the high-quality development of the petrochemical industry.

[0006] To achieve the above object, a first aspect of the present invention provides a low-carbon and low-nitrogen industrial heating system, which includes an industrial furnace, a fossil fuel burner, and a low-carbon fuel burner;

[0007] The fossil fuel burner is disposed at the bottom and / or side wall of the industrial furnace; the fossil fuel burner is provided with an air-side inlet and a fossil fuel-side inlet;

[0008] The industrial furnace is provided with an air inlet and a top flue gas outlet;

[0009] The low-carbon fuel burner is provided with an air inlet and an air outlet; the air inlet is connected with an air intake pipeline and a low-carbon fuel pipeline; the air outlet is connected with the air-side inlet, and / or, with the air inlet of the industrial furnace;

[0010] The fossil fuel-side inlet is connected with a fossil fuel pipeline;

[0011] The top flue gas outlet of the industrial furnace is connected to a chimney through a flue gas pipeline.

[0012] According to the present invention, preferably, the system further includes a flue gas-air preheater; the flue gas-air preheater is provided with a hot flue gas inlet, a cold flue gas outlet, a cold air inlet, and a hot air outlet; the low-carbon fuel burner is disposed downstream or upstream of the air side of the flue gas-air preheater;

[0013] When the low-carbon fuel burner is disposed downstream of the air side of the flue gas-air preheater: the first section of the air intake pipeline is connected with the cold air inlet, and the hot air outlet is connected with the air inlet of the low-carbon fuel burner through the second section of the air intake pipeline; the flue gas pipeline is connected with the hot flue gas inlet, and the cold flue gas outlet is connected to the chimney;

[0014] When the low-carbon fuel burner is disposed upstream of the air side of the flue gas-air preheater: the air outlet of the low-carbon fuel burner is connected with the cold air inlet, and the hot air outlet is connected with the air-side inlet through a hot air outlet pipeline, and / or, with the air inlet provided in the industrial furnace; the flue gas pipeline is connected with the hot flue gas inlet, and the cold flue gas outlet is connected to the chimney.

[0015] According to the present invention, preferably, the air intake pipeline is provided with a bypass to enable all or part of the air to flow through the low-carbon fuel burner to control the flame temperature of the low-carbon fuel burner. Among them, the air that does not flow through the low-carbon fuel burner is sent to at least one of the air-side inlet of the fossil fuel burner, the cold air inlet of the flue gas-air preheater, and the air inlet of the industry. Specifically:

[0016] When the low-carbon fuel burner is downstream of the flue gas-air preheater, the air that does not flow through the low-carbon fuel burner directly goes to the fossil fuel burner or the furnace;

[0017] When the low-carbon fuel burner is upstream of the flue gas-air preheater, the air that does not flow through the low-carbon fuel burner directly goes to the flue gas-air preheater or the fossil fuel burner or the furnace;

[0018] The cold air can also directly enter the furnace to supplement the oxygen in the furnace without flowing through the flue gas-air preheater and the burner. Generally, not 100% of the air flows into the furnace at this time.

[0019] According to the present invention, preferably, the system further includes an induced draft fan and / or a blower; the cold flue gas outlet is connected to the chimney through the induced draft fan; the blower is connected to the other end of the air intake pipe.

[0020] According to the present invention, preferably, the low-carbon fuel burner is further provided with an oxygen input port, and the oxygen input port is connected to a pure oxygen pipe and / or an oxygen-enriched pipe.

[0021] According to the present invention, preferably, the system further includes a feedback control subsystem; the feedback control subsystem includes a control unit, a target temperature signal monitoring and feedback unit, a low-carbon fuel flow monitoring unit, a low-carbon fuel flow control unit, a fossil fuel flow monitoring unit, a fossil fuel flow control unit, and a high-temperature flue gas oxygen content monitoring and feedback unit;

[0022] The target temperature signal monitoring and feedback unit is used to monitor the heating temperature in the industrial furnace and / or the heating temperature at the outlet of the heated medium in the industrial furnace and feed back the temperature data to the control unit;

[0023] The low-carbon fuel flow monitoring unit is used to monitor the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feed back the low-carbon fuel flow data to the control unit;

[0024] The fossil fuel flow monitoring unit is used to monitor the magnitude of the fossil fuel flow entering the fossil fuel burner and feed back the fossil fuel flow data to the control unit;

[0025] The high-temperature flue gas oxygen content monitoring and feedback unit is used to monitor the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner and feed back the oxygen content data to the control unit;

[0026] The control unit is used to control the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and the magnitude of the fossil fuel flow entering the fossil fuel burner respectively through the low-carbon fuel flow control unit and the fossil fuel flow control unit.

[0027] The second aspect of the present invention provides a low-carbon and low-nitrogen industrial heating method. The method uses the described system and includes the following steps:

[0028] S1: Feed air and low-carbon fuel into the low-carbon fuel burner for combustion to obtain high-temperature flue gas;

[0029] S2: Feed the high-temperature flue gas into the fossil fuel burner to mix with fossil fuel for combustion, and / or feed it into the industrial furnace to provide heat energy for the industrial furnace;

[0030] Obtain combustion gas in the fossil fuel burner, and feed the combustion gas into the industrial furnace to provide heat energy for the industrial furnace;

[0031] S3: Send the flue gas in the industrial furnace through the top flue gas outlet to the chimney through the flue gas pipeline and then discharge it to the atmosphere.

[0032] According to the present invention, preferably, before feeding the air in step S1 into the low-carbon fuel burner, exchange heat between the air and the flue gas discharged from the flue gas pipeline in step S3 in the flue gas-air preheater to obtain heated air and cooled flue gas;

[0033] Feed the heated air and low-carbon fuel into the low-carbon fuel burner for combustion to obtain high-temperature flue gas;

[0034] Send the cooled flue gas to the chimney and then discharge it to the atmosphere.

[0035] According to the present invention, preferably, before performing step S2, exchange heat between the high-temperature flue gas and the flue gas discharged from the flue gas pipeline in step S3 in the flue gas-air preheater to obtain heated flue gas and cooled flue gas;

[0036] Feed the heated flue gas into the fossil fuel burner through the hot air outlet pipeline, and / or feed it into the industrial furnace to provide heat energy for the industrial furnace;

[0037] Send the cooled flue gas to the chimney and then discharge it to the atmosphere.

[0038] According to the present invention, preferably, the method further includes: using the target temperature signal monitoring and feedback unit to monitor the heating temperature in the industrial furnace and / or the heating temperature at the outlet of the heated medium in the industrial furnace and feedback the temperature data to the control unit; setting an industrial furnace temperature set value in the control unit; using the control unit to make the difference between the industrial furnace temperature set value and the temperature data stable at a first control threshold; and when the difference between the industrial furnace temperature set value and the temperature data exceeds the first control threshold:

[0039] The control unit is used to issue instructions to the low-carbon fuel flow control unit and the fossil fuel flow control unit respectively, and then the low-carbon fuel flow control unit is used to control the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner, and the fossil fuel flow control unit is used to control the magnitude of the fossil fuel flow entering the fossil fuel burner; meanwhile, the low-carbon fuel flow monitoring unit is used to monitor the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feedback the low-carbon fuel flow data to the control unit; and the fossil fuel flow monitoring unit is used to monitor the magnitude of the fossil fuel flow entering the fossil fuel burner and feedback the fossil fuel flow data to the control unit; so that the difference between the industrial furnace temperature set value and the temperature data is stabilized within the first control threshold.

[0040] According to the present invention, preferably, the industrial furnace temperature set value is the set value of the heating temperature in the industrial furnace of 550°C - 1300°C, and / or the set value of the heating temperature at the outlet of the heated medium in the industrial furnace of 200°C - 1000°C (determined according to the medium properties and heating requirements). (Wherein, the "heating temperature at the outlet of the heated medium in the industrial furnace" is the temperature when the medium heated in the industrial furnace flows out of the industrial furnace; the heated medium in the industrial furnace is the fluid to be heated in the furnace tube and / or the workpiece to be heated in the furnace chamber; the "heating temperature in the industrial furnace" is the temperature in the furnace chamber)

[0041] According to the present invention, preferably, the first control threshold is 1 - 20°C.

[0042] According to the present invention, preferably, when the difference between the industrial furnace temperature set value and the temperature data is stabilized within the first control threshold, the control unit is used to control the flow rates of the low-carbon fuel and the fossil fuel according to the temperature data, so as to achieve the quantitative carbon dioxide emission of the system or achieve the variable carbon dioxide emission of the system;

[0043] Preferably, the control unit is used to fix the flow rate of the fossil fuel according to the temperature data, and the control unit is used to adjust the flow rate of the low-carbon fuel according to the temperature data, so as to achieve the quantitative carbon dioxide emission of the system;

[0044] Preferably, the control unit is used to fix the flow rate of the low-carbon fuel according to the temperature data, and the control unit is used to adjust the flow rate of the fossil fuel according to the temperature data, so as to achieve the variable carbon dioxide emission of the system;

[0045] Preferably, the control unit is used to adjust the flow rates of the low-carbon fuel and the fossil fuel according to the temperature data, so as to achieve the variable carbon dioxide emission of the system.

[0046] According to the present invention, preferably, the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner is monitored by the high-temperature flue gas oxygen content monitoring and feedback unit and the oxygen content data is fed back to the control unit; an oxygen content set value in the high-temperature flue gas is set in the control unit; under the condition that the total heat release of the low-carbon fuel and the fossil fuel remains unchanged, the control unit is used to control the difference between the oxygen content data and the oxygen content set value to be stable at a second control threshold, thereby reducing the content of nitrogen oxides in the combustion gas;

[0047] When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is higher than the oxygen content set value: the control unit is used to send an increasing instruction to the low-carbon fuel flow control unit, and then the low-carbon fuel flow control unit is used to increase the low-carbon fuel flow rate entering the low-carbon fuel burner; and the control unit is used to send a decreasing instruction to the fossil fuel flow control unit, and then the fossil fuel flow control unit is used to reduce the fossil fuel flow rate entering the fossil fuel burner; meanwhile, the low-carbon fuel flow monitoring unit is used to monitor the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and feed back the low-carbon fuel flow data to the control unit; the fossil fuel flow monitoring unit is used to monitor the magnitude of the fossil fuel flow rate entering the fossil fuel burner and feed back the fossil fuel flow data to the control unit; so that the difference between the oxygen content data and the oxygen content set value is stable at the second control threshold, thereby reducing the content of nitrogen oxides in the combustion gas;

[0048] When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is lower than the oxygen content set value: the control unit is used to send a decreasing instruction to the low-carbon fuel flow control unit, and then the low-carbon fuel flow control unit is used to reduce the low-carbon fuel flow rate entering the low-carbon fuel burner; the control unit is used to send an increasing instruction to the fossil fuel flow control unit, and then the fossil fuel flow control unit is used to increase the fossil fuel flow rate entering the fossil fuel burner; meanwhile, the low-carbon fuel flow monitoring unit is used to monitor the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and feed back the low-carbon fuel flow data to the control unit; the fossil fuel flow monitoring unit is used to monitor the magnitude of the fossil fuel flow rate entering the fossil fuel burner and feed back the fossil fuel flow data to the control unit; so that the difference between the oxygen content data and the oxygen content set value is stable at the second control threshold, thereby reducing the content of nitrogen oxides in the combustion gas.

[0049] According to the present invention, preferably, the oxygen content set value is 10-35 mol% by mole, and more preferably 15-20 mol% by mole.

[0050] According to the present invention, preferably, the second control threshold is 0.5 - 3.5% in mole percentage.

[0051] According to the present invention, preferably, the method further includes adjusting the oxygen content in the high-temperature flue gas by adjusting the air supply volume of the blower.

[0052] According to the present invention, preferably, the method further includes inputting pure oxygen and / or oxygen-enriched air into the low-carbon fuel burner through the oxygen input port to adjust the oxygen content in the high-temperature flue gas.

[0053] In the present invention, in the low-carbon fuel burner, the low-carbon fuel is mixed with excess air and undergoes staged combustion. The "staged combustion" refers to a form in which the fuel and / or air are injected into different regions of the flame in two or more separate streams for combustion.

[0054] According to the present invention, preferably, the mole percentage of oxygen in the high-temperature flue gas is 0 - 35%, and preferably, the mole percentage of oxygen in the high-temperature flue gas is 15 - 20%, at which time the control effect of nitrogen oxide emissions is better.

[0055] According to the present invention, preferably, the low-carbon fuel burner is at least one of a burner using hydrogen as fuel, a burner using ammonia as fuel, and a burner using biomass as fuel; preferably, the low-carbon fuel burner is a green hydrogen burner using hydrogen produced by electrolyzing water with green electricity; further preferably, the green electricity is green electricity generated in at least one of the forms of light, wind, water, and nuclear.

[0056] In the present invention, the low-carbon fuel and the fossil fuel supply heat together. Therefore, the use of fossil fuel is reduced, and since the low-carbon fuel does not produce carbon dioxide when burned, the carbon dioxide emissions of the system are thus reduced. Moreover, when the low-carbon fuel is burned, the excess air reduces the flame temperature, and together with the reducing property of the low-carbon fuel (green hydrogen), it inhibits the formation of nitrogen oxides. When the high-temperature flue gas generated in step S1 enters the fossil fuel burner for combustion support, due to the low oxygen concentration, the flame temperature is inhibited, so the formation of nitrogen oxides during the combustion process of the fossil fuel is inhibited, and the overall combustion process is low-nitrogen.

[0057] In the present invention, when the input low-carbon fuel continues to increase, the fossil fuel will continue to decrease, and the oxygen content in the high-temperature flue gas generated in step S1 tends to 0. Eventually, all the energy required by the industrial furnace can be provided by the low-carbon fuel, that is, the direct carbon dioxide emissions of the industrial furnace are zero.

[0058] The beneficial effects of the technical solution of the present invention are as follows:

[0059] (1) The present invention introduces low-carbon energy through a low-carbon fuel burner, reducing the carbon dioxide emissions of the system. By controlling the air supply of the low-carbon fuel burner and the oxygen content of the combustion gas (i.e., the oxygen content of the combustion-supporting gas of the fossil fuel burner), the nitrogen oxide emissions of the system can be reduced, achieving low-carbon and low-nitrogen combustion for heating.

[0060] (2) The low-carbon fuel and fossil fuel of the present invention coexist in an industrial heating system. During the operation of the industrial furnace, the input ratio of the low-carbon fuel to the fossil energy can be flexibly adjusted.

[0061] (3) The present invention does not change the main structure of the industrial heating system, reducing the design and manufacturing difficulty.

[0062] (4) The present invention has low requirements for the supply stability of the low-carbon fuel, enhancing the energy adaptability of the system. It can use solid-phase biomass fuels without secondary processing.

[0063] (5) The system of the present invention is suitable for tubular heating furnaces, industrial furnaces with reactions, incinerators, etc., with strong applicability.

[0064] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0065] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more apparent. Among them, in the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0066] Figure 1 The figure shows a schematic diagram of a low-carbon and low-nitrogen industrial heating system provided in Embodiment 1 of the present invention.

[0067] Figure 2 The figure shows a schematic diagram of a low-carbon and low-nitrogen industrial heating system provided in Embodiment 2 of the present invention.

[0068] Figure 3 The figure shows a schematic diagram of a low-carbon and low-nitrogen industrial heating system provided in Embodiment 3 of the present invention.

[0069] The description of the reference numerals in the drawings is as follows:

[0070] 1 Industrial furnace; 2 Flue gas-air preheater; 3 Induced draft fan; 4 Blower; 5 Chimney; 6 Hot flue gas inlet; 7 Cold flue gas outlet; 8 Control unit; 9 Cold air inlet; 10 Hot air outlet; 11 Fossil fuel burner; 12 Flue gas pipeline; 13 Air intake pipeline; 13-1 The first section of the air intake pipeline; 13-2 The second section of the air intake pipeline; 14 Fossil fuel pipeline; 15 Low-carbon fuel pipeline; 21 Low-carbon fuel burner.

[0071] F1 Fossil fuels; F2 Flue gas in industrial furnaces; F3 Cooling flue gas; F4 Air; F5 Heating air; F6 High-temperature flue gas; E1 Low-carbon fuels;

[0072] C1 Target temperature signal monitoring and feedback unit; C2 Low-carbon fuel flow monitoring unit; C3 Low-carbon fuel flow control unit; C4 Fossil fuel flow monitoring unit; C5 Fossil fuel flow control unit; C6 High-temperature flue gas oxygen content monitoring and feedback unit. Detailed implementation manners

[0073] The preferred implementation manners of the present invention will be described in more detail below. Although the preferred implementation manners of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the implementation manners set forth herein. On the contrary, these implementation manners are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0074] Embodiment 1

[0075] This embodiment provides a low-carbon and low-nitrogen industrial heating system, as Figure 1 shown, the system includes an industrial furnace 1, a flue gas-air preheater 2, a fossil fuel burner 11 and a low-carbon fuel burner 21;

[0076] The fossil fuel burner 11 is arranged at the bottom of the industrial furnace 1; the fossil fuel burner 11 is provided with an air-side inlet and a fossil fuel-side inlet;

[0077] The industrial furnace 1 is provided with an air inlet and a top flue gas outlet;

[0078] The flue gas-air preheater 2 is provided with a hot flue gas inlet 6, a cold flue gas outlet 7, a cold air inlet 9 and a hot air outlet 10;

[0079] The low-carbon fuel burner 21 is arranged downstream of the air side of the flue gas-air preheater 2; the low-carbon fuel burner 21 is provided with an air inlet and an air outlet;

[0080] The air inlet is connected with an air intake pipe and a low-carbon fuel pipe 15, wherein the first section 13-1 of the air intake pipe is connected with the cold air inlet 9, and the hot air outlet 10 is connected with the air inlet of the low-carbon fuel burner 21 through the second section 13-2 of the air intake pipe; the blower 4 is connected with the other end of the first section 13-1 of the air intake pipe;

[0081] The air outlet is connected with the air-side inlet;

[0082] The fossil fuel-side inlet is connected with a fossil fuel pipe 14;

[0083] The top flue gas outlet of the industrial furnace 1 is connected to the hot flue gas inlet 6 through a flue gas pipeline 12, and the cold flue gas outlet 7 is connected to the chimney 5 through the induced draft fan 3.

[0084] This embodiment also provides a low-carbon and low-nitrogen industrial heating method, which uses the above system and includes the following steps:

[0085] S1: Exchange heat between air and the flue gas (flue gas F2 in the industrial furnace) discharged from the flue gas pipeline in step S3 in the flue gas-air preheater 2 to obtain heated air F5 and cooled flue gas F3; Feed the heated air F5 and low-carbon fuel E1 into the low-carbon fuel burner 21 for combustion to obtain high-temperature flue gas F6;

[0086] Wherein: the low-carbon fuel E1 is green hydrogen produced by electrolyzing water with green electricity, and the green electricity is green electricity generated in at least one form of light, wind, water, and nuclear.

[0087] Under the condition that the total heat release of the low-carbon fuel E1 and the fossil fuel F1 remains unchanged, adjust the flow rate of the low-carbon fuel E1 and the flow rate of the fossil fuel F1 so that the molar percentage content of oxygen in the high-temperature flue gas F6 is 16%, reducing the content of nitrogen oxides in the combustion gas.

[0088] S2: Feed the high-temperature flue gas F6 into the fossil fuel burner 11 to mix and burn with the fossil fuel F1; Obtain combustion gas (the molar percentage content of oxygen in the combustion gas is 1.5%) in the fossil fuel burner 11, and feed the combustion gas into the industrial furnace 1 to provide heat energy for the target medium to be heated in the industrial furnace.

[0089] S3: Feed the flue gas F2 in the industrial furnace through the top flue gas outlet to the flue gas-air preheater 2 through the flue gas pipeline 12 first, and then send it to the chimney 5 through the induced draft fan 3 through the cold flue gas outlet 7 and discharge it to the atmosphere.

[0090] Obtain the carbon dioxide content in the flue gas of step S3 of this embodiment by flue gas sampling analysis, and measure the nitrogen oxides in the flue gas of step S3 of this embodiment with a NOx analyzer. It can be known from the test detection that:

[0091] The carbon dioxide content in the flue gas of step S3 of this embodiment is 5.9% v (the fossil fuel is refinery gas). When the method of this embodiment is not adopted, the carbon dioxide content in the flue gas discharged to the atmosphere is 8.5% v;

[0092] The content of nitrogen oxides in the flue gas of step S3 of this embodiment is 23 mg / Nm 3(When the furnace temperature is 785 - 790 °C), when the method of this embodiment is not adopted, the content of nitrogen oxides in the flue gas discharged to the atmosphere is 62 mg / Nm 3 .

[0093] Example 2

[0094] This embodiment provides a low-carbon and low-nitrogen industrial heating system. As Figure 2 shown, the system includes an industrial furnace 1, a fossil fuel burner 11, and a low-carbon fuel burner 21;

[0095] The fossil fuel burner 11 is arranged at the bottom and side walls of the industrial furnace; the fossil fuel burner 11 is provided with an air-side inlet and a fossil fuel-side inlet;

[0096] The industrial furnace 1 is provided with an air inlet and a top flue gas outlet;

[0097] The low-carbon fuel burner 21 is provided with an air inlet and an air outlet;

[0098] The air inlet is connected to an air intake pipe 13 and a low-carbon fuel pipe 15, and the blower 4 is connected to the other end of the air intake pipe 13;

[0099] The air outlet is connected to the air-side inlet;

[0100] The fossil fuel-side inlet is connected to a fossil fuel pipe 14;

[0101] The top flue gas outlet of the industrial furnace 1 is connected to the chimney 5 through a flue gas pipe 12.

[0102] This embodiment also provides a low-carbon and low-nitrogen industrial heating method. The method uses the above system and includes the following steps:

[0103] S1: Feed air F4 and low-carbon fuel E1 into the low-carbon fuel burner 21 for combustion to obtain high-temperature flue gas F6;

[0104] Wherein: the low-carbon fuel E1 is green hydrogen produced by electrolyzing water with green electricity, and the green electricity is green electricity generated in at least one form of light, wind, water, and nuclear;

[0105] Without changing the total heat release of the low-carbon fuel E1 and the fossil fuel F1, adjust the flow rate of the low-carbon fuel E1 and the flow rate of the fossil fuel F1 so that the molar percentage of oxygen in the high-temperature flue gas F6 is 17%, and reduce the content of nitrogen oxides in the combustion gas.

[0106] S2: Feed the high-temperature flue gas F6 into the fossil fuel burner 11 to mix with the fossil fuel F1 for combustion; obtain combustion gas in the fossil fuel burner 11, and feed the combustion gas into the industrial furnace 1 to provide heat energy for the target medium to be heated in the industrial furnace 1;

[0107] S3: Send the flue gas F2 in the industrial furnace to the chimney 5 through the top flue gas outlet via the flue gas pipeline 12 and then discharge it to the atmosphere.

[0108] Obtain the carbon dioxide content in the flue gas of step S3 of this embodiment by flue gas sampling analysis, and measure the nitrogen oxides in the flue gas of step S3 of this embodiment using a NOx analyzer. It can be known from the test detection that:

[0109] The carbon dioxide content in the flue gas of step S3 of this embodiment is 6.4% v (the fossil fuel is refinery gas). When the method of this embodiment is not adopted, the carbon dioxide content in the flue gas discharged to the atmosphere is 8.5% v;

[0110] The content of nitrogen oxides in the flue gas of step S3 of this embodiment is 29 mg / Nm 3 (the furnace temperature is 795 - 805 °C). When the method of this embodiment is not adopted, the content of nitrogen oxides in the flue gas discharged to the atmosphere is 55 mg / Nm 3 .

[0111] Example 3

[0112] This embodiment provides a low-carbon and low-nitrogen industrial heating system. As Figure 3 shown, the difference between this embodiment and Embodiment 1 is only that:

[0113] The system further includes a feedback control subsystem; the feedback control subsystem includes a control unit 8, a target temperature signal monitoring and feedback unit C1, a low-carbon fuel flow monitoring unit C2, a low-carbon fuel flow control unit C3, a fossil fuel flow monitoring unit C4, a fossil fuel flow control unit C5, and a high-temperature flue gas oxygen content monitoring and feedback unit C6;

[0114] The target temperature signal monitoring and feedback unit C1 is used to monitor the heating temperature at the outlet of the heated medium in the industrial furnace and feed the temperature data back to the control unit;

[0115] The low-carbon fuel flow monitoring unit C2 is used to monitor the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feed the low-carbon fuel flow data back to the control unit;

[0116] The fossil fuel flow monitoring unit C4 is used to monitor the magnitude of the fossil fuel flow entering the fossil fuel burner and feed the fossil fuel flow data back to the control unit;

[0117] The high-temperature flue gas oxygen content monitoring and feedback unit C6 is used to monitor the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner and feed back the oxygen content data to the control unit;

[0118] The control unit is used to control the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and the magnitude of the fossil fuel flow rate entering the fossil fuel burner through the low-carbon fuel flow control unit C3 and the fossil fuel flow control unit C5 respectively.

[0119] This embodiment also provides a low-carbon and low-nitrogen industrial heating method. The difference between this method and that of Embodiment 1 is only that:

[0120] The method for "ensuring that the total heat release of the low-carbon fuel and the fossil fuel remains basically unchanged" is as follows: The target temperature signal monitoring and feedback unit C1 is used to monitor the heating temperature at the outlet of the heated medium in the industrial furnace and feed back the temperature data to the control unit; An industrial furnace temperature set value (the heating temperature set value at the outlet of the heated medium in the industrial furnace is 380 °C) is set in the control unit; The control unit is used to make the difference between the industrial furnace temperature set value and the temperature data stable at a first control threshold of 3 °C (that is, to ensure that the total heat release of the low-carbon fuel and the fossil fuel remains basically unchanged). When the difference between the industrial furnace temperature set value and the temperature data exceeds the first control threshold:

[0121] The control unit is used to send instructions to the low-carbon fuel flow control unit C3 and the fossil fuel flow control unit C5 respectively, and then the low-carbon fuel flow control unit C3 is used to control the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner, and the fossil fuel flow control unit C5 is used to control the magnitude of the fossil fuel flow rate entering the fossil fuel burner; At the same time, the low-carbon fuel flow monitoring unit C2 is used to monitor the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and feed back the low-carbon fuel flow rate data to the control unit; And the fossil fuel flow monitoring unit C4 is used to monitor the magnitude of the fossil fuel flow rate entering the fossil fuel burner and feed back the fossil fuel flow rate data to the control unit; Make the difference between the industrial furnace temperature set value and the temperature data stable at the first control threshold.

[0122] The method of "adjusting the flow rates of the low-carbon fuel and the fossil fuel so that the molar percentage content of oxygen in the high-temperature flue gas is 16%, and reducing the content of nitrogen oxides in the combustion gas" is as follows: Using the high-temperature flue gas oxygen content monitoring and feedback unit C6 to monitor the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner and feedback the oxygen content data to the control unit; setting the oxygen content set value in the high-temperature flue gas (i.e., the molar percentage content of 16%) in the control unit; under the condition that the total heat release of the low-carbon fuel and the fossil fuel remains unchanged, using the control unit to control the difference between the oxygen content data and the oxygen content set value to be stable at the second control threshold (i.e., the molar percentage content of 1%), thereby reducing the content of nitrogen oxides in the combustion gas;

[0123] When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is higher than the oxygen content set value: Using the control unit to send an increase instruction to the low-carbon fuel flow control unit C3, and then using the low-carbon fuel flow control unit C3 to increase the flow rate of the low-carbon fuel entering the low-carbon fuel burner; and using the control unit to send a decrease instruction to the fossil fuel flow control unit C5, and then using the fossil fuel flow control unit C5 to reduce the flow rate of the fossil fuel entering the fossil fuel burner; at the same time, using the low-carbon fuel flow monitoring unit C2 to monitor the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and feedback the low-carbon fuel flow data to the control unit; using the fossil fuel flow monitoring unit C4 to monitor the magnitude of the fossil fuel flow rate entering the fossil fuel burner and feedback the fossil fuel flow data to the control unit; making the difference between the oxygen content data and the oxygen content set value stable at the second control threshold, thereby reducing the content of nitrogen oxides in the combustion gas;

[0124] When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is lower than the oxygen content set value: the control unit issues a reduction instruction to the low-carbon fuel flow control unit C3, and then the low-carbon fuel flow control unit C3 reduces the low-carbon fuel flow entering the low-carbon fuel burner; the control unit issues an increase instruction to the fossil fuel flow control unit C5, and then the fossil fuel flow control unit C5 increases the fossil fuel flow entering the fossil fuel burner; meanwhile, the low-carbon fuel flow monitoring unit C2 monitors the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feeds back the low-carbon fuel flow data to the control unit; the fossil fuel flow monitoring unit C4 monitors the magnitude of the fossil fuel flow entering the fossil fuel burner and feeds back the fossil fuel flow data to the control unit; and the difference between the oxygen content data and the oxygen content set value is stabilized at the second control threshold, thereby reducing the nitrogen oxide content in the combustion gas.

[0125] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low-carbon and low-nitrogen industrial heating system, characterized in that, The system includes an industrial furnace, a fossil fuel burner, and a low-carbon fuel burner; The fossil fuel burner is disposed at the bottom and / or sidewall of the industrial furnace; the fossil fuel burner is provided with an air-side inlet and a fossil fuel-side inlet; The industrial furnace is provided with an air inlet and a top flue gas outlet; The low-carbon fuel burner is provided with an air inlet and an air outlet; the air inlet is connected to an air intake pipe and a low-carbon fuel pipe; the air outlet is connected to the air-side inlet, and / or, to the air inlet provided in the industrial furnace; The fossil fuel-side inlet is connected to a fossil fuel pipe; The top flue gas outlet of the industrial furnace is connected to a chimney through a flue gas pipe.

2. The low-carbon and low-nitrogen industrial heating system according to claim 1, wherein, The system further includes a flue gas-air preheater; the flue gas-air preheater is provided with a hot flue gas inlet, a cold flue gas outlet, a cold air inlet, and a hot air outlet; the low-carbon fuel burner is disposed downstream or upstream of the air side of the flue gas-air preheater; When the low-carbon fuel burner is disposed downstream of the air side of the flue gas-air preheater: the first section of the air intake pipe is connected to the cold air inlet, and the hot air outlet is connected to the air inlet of the low-carbon fuel burner through the second section of the air intake pipe; the flue gas pipe is connected to the hot flue gas inlet, and the cold flue gas outlet is connected to the chimney; When the low-carbon fuel burner is disposed upstream of the air side of the flue gas-air preheater: the air outlet of the low-carbon fuel burner is connected to the cold air inlet, and the hot air outlet is connected to the air-side inlet through a hot air outlet pipe, and / or, to the air inlet provided in the industrial furnace; the flue gas pipe is connected to the hot flue gas inlet, and the cold flue gas outlet is connected to the chimney.

3. The low-carbon and low-nitrogen industrial heating system according to claim 1, wherein, The air intake pipe is provided with a bypass to enable all or part of the air to flow through the low-carbon fuel burner; The system further includes an induced draft fan and / or a blower; the cold flue gas outlet is connected to the chimney through the induced draft fan; the blower is connected to the other end of the air intake pipe; The low-carbon fuel burner is further provided with an oxygen input port, and the oxygen input port is connected to a pure oxygen pipe and / or an oxygen-enriched pipe.

4. The low-carbon and low-nitrogen industrial heating system according to claim 1, wherein, The system further includes a feedback control subsystem; the feedback control subsystem includes a control unit, a target temperature signal monitoring and feedback unit, a low-carbon fuel flow monitoring unit, a low-carbon fuel flow control unit, a fossil fuel flow monitoring unit, a fossil fuel flow control unit, and a high-temperature flue gas oxygen content monitoring and feedback unit; The target temperature signal monitoring and feedback unit is configured to monitor the heating temperature inside the industrial furnace and / or the heating temperature at the outlet of the heated medium in the industrial furnace and feedback the temperature data to the control unit; The low-carbon fuel flow monitoring unit is configured to monitor the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feedback the low-carbon fuel flow data to the control unit; The fossil fuel flow monitoring unit is configured to monitor the magnitude of the fossil fuel flow entering the fossil fuel burner and feedback the fossil fuel flow data to the control unit; The high-temperature flue gas oxygen content monitoring and feedback unit is used to monitor the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner and feedback the oxygen content data to the control unit; The control unit is used to control the magnitude of the low-carbon fuel flow rate entering the low-carbon fuel burner and the magnitude of the fossil fuel flow rate entering the fossil fuel burner respectively through the low-carbon fuel flow control unit and the fossil fuel flow control unit.

5. A low-carbon and low-nitrogen industrial heating method, characterized in that, The method adopts the system described in any one of claims 1-4, and includes the following steps: S1: Feed air and low-carbon fuel into the low-carbon fuel burner for combustion to obtain high-temperature flue gas; S2: Feed the high-temperature flue gas into the fossil fuel burner to be mixed with fossil fuel for combustion, and / or feed it into the industrial furnace to provide heat energy for the industrial furnace; Obtain combustion gas in the fossil fuel burner, and feed the combustion gas into the industrial furnace to provide heat energy for the industrial furnace; S3: Send the flue gas in the industrial furnace to the chimney through the top flue gas outlet through the flue gas pipeline and then discharge it to the atmosphere.

6. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, Before feeding the air in step S1 into the low-carbon fuel burner, exchange heat between the air and the flue gas discharged from the flue gas pipeline in step S3 in the flue gas-air preheater to obtain heated air and cooled flue gas; Feed the heated air and low-carbon fuel into the low-carbon fuel burner for combustion to obtain high-temperature flue gas; Send the cooled flue gas to the chimney and then discharge it to the atmosphere.

7. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, Before performing step S2, exchange heat between the high-temperature flue gas and the flue gas discharged from the flue gas pipeline in step S3 in the flue gas-air preheater to obtain heated flue gas and cooled flue gas; Feed the heated flue gas into the fossil fuel burner through the hot air outlet pipeline, and / or feed it into the industrial furnace to provide heat energy for the industrial furnace; Send the cooled flue gas to the chimney and then discharge it to the atmosphere.

8. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The method further includes: using the target temperature signal monitoring and feedback unit to monitor the heating temperature in the industrial furnace and / or the heating temperature at the outlet of the heated medium of the industrial furnace and feedback the temperature data to the control unit; setting an industrial furnace temperature set value in the control unit; using the control unit to make the difference between the industrial furnace temperature set value and the temperature data stable at a first control threshold; and when the difference between the industrial furnace temperature set value and the temperature data exceeds the first control threshold: The control unit is used to issue instructions to the low-carbon fuel flow control unit and the fossil fuel flow control unit respectively, and then the low-carbon fuel flow control unit is used to control the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner, and the fossil fuel flow control unit is used to control the magnitude of the fossil fuel flow entering the fossil fuel burner; meanwhile, the low-carbon fuel flow monitoring unit is used to monitor the magnitude of the low-carbon fuel flow entering the low-carbon fuel burner and feed back the low-carbon fuel flow data to the control unit; and the fossil fuel flow monitoring unit is used to monitor the magnitude of the fossil fuel flow entering the fossil fuel burner and feed back the fossil fuel flow data to the control unit; so that the difference between the industrial furnace temperature set value and the temperature data is stabilized at a first control threshold; Preferably, the industrial furnace temperature set value is the set value of the heating temperature in the industrial furnace of 550°C - 1300°C, and / or, the set value of the heating temperature at the outlet of the heated medium of the industrial furnace of 200°C - 1000°C; Preferably, the first control threshold is 1 - 20°C.

9. The low-carbon and low-nitrogen industrial heating method according to claim 8, wherein, When the difference between the industrial furnace temperature set value and the temperature data is stabilized at the first control threshold, the control unit is used to control the flow rates of the low-carbon fuel and the fossil fuel according to the temperature data, so as to achieve the quantitative emission of carbon dioxide in the system or achieve the variable emission of carbon dioxide in the system; Preferably, the control unit is used to control the flow rate of the fossil fuel to be fixed according to the temperature data, and the control unit is used to adjust the flow rate of the low-carbon fuel according to the temperature data, so as to achieve the quantitative emission of carbon dioxide in the system; Preferably, the control unit is used to control the flow rate of the low-carbon fuel to be fixed according to the temperature data, and the control unit is used to adjust the flow rate of the fossil fuel according to the temperature data, so as to achieve the variable emission of carbon dioxide in the system; Preferably, the control unit is used to adjust the flow rates of the low-carbon fuel and the fossil fuel according to the temperature data, so as to achieve the variable emission of carbon dioxide in the system.

10. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The high-temperature flue gas oxygen content monitoring and feedback unit is used to monitor the oxygen content in the high-temperature flue gas generated by the low-carbon fuel burner and feed back the oxygen content data to the control unit; the oxygen content set value in the high-temperature flue gas is set in the control unit; under the condition that the total heat release of the low-carbon fuel and the fossil fuel remains unchanged, the control unit is used to control the difference between the oxygen content data and the oxygen content set value to be stabilized at a second control threshold, thereby reducing the content of nitrogen oxides in the combustion gas; When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is higher than the oxygen content set value: The control unit issues an increase command to the low-carbon fuel flow control unit, and then the low-carbon fuel flow control unit increases the low-carbon fuel flow rate into the low-carbon fuel burner; and the control unit issues a decrease command to the fossil fuel flow control unit, and then the fossil fuel flow control unit decreases the fossil fuel flow rate into the fossil fuel burner; At the same time, the low-carbon fuel flow monitoring unit monitors the magnitude of the low-carbon fuel flow rate into the low-carbon fuel burner and feeds back the low-carbon fuel flow data to the control unit; the fossil fuel flow monitoring unit monitors the magnitude of the fossil fuel flow rate into the fossil fuel burner and feeds back the fossil fuel flow data to the control unit; The difference between the oxygen content data and the oxygen content set value is stabilized at the second control threshold, thereby reducing the nitrogen oxide content in the combustion gas; When the difference between the oxygen content data and the oxygen content set value exceeds the second control threshold and the oxygen content data is lower than the oxygen content set value: The control unit issues a decrease command to the low-carbon fuel flow control unit, and then the low-carbon fuel flow control unit decreases the low-carbon fuel flow rate into the low-carbon fuel burner; the control unit issues an increase command to the fossil fuel flow control unit, and then the fossil fuel flow control unit increases the fossil fuel flow rate into the fossil fuel burner; At the same time, the low-carbon fuel flow monitoring unit monitors the magnitude of the low-carbon fuel flow rate into the low-carbon fuel burner and feeds back the low-carbon fuel flow data to the control unit; the fossil fuel flow monitoring unit monitors the magnitude of the fossil fuel flow rate into the fossil fuel burner and feeds back the fossil fuel flow data to the control unit; The difference between the oxygen content data and the oxygen content set value is stabilized at the second control threshold, thereby reducing the nitrogen oxide content in the combustion gas; Preferably, the oxygen content set value is 10-35 mol%, and more preferably 15-20 mol%; Preferably, the second control threshold is 0.5-3.5 mol%.

11. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The method further includes adjusting the oxygen content in the high-temperature flue gas by adjusting the air supply volume of the blower.

12. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The method further includes inputting pure oxygen and / or oxygen-enriched gas into the low-carbon fuel burner through the oxygen input port to adjust the oxygen content in the high-temperature flue gas.

13. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The molar percentage of oxygen in the high-temperature flue gas is 0-35%, and preferably, the molar percentage of oxygen in the high-temperature flue gas is 15-20%.

14. The low-carbon and low-nitrogen industrial heating method according to claim 5, wherein, The low-carbon fuel burner is at least one of a burner fueled by hydrogen, a burner fueled by ammonia, and a burner fueled by biomass; preferably, the low-carbon fuel burner is a green hydrogen burner fueled by hydrogen produced by electrolyzing water with green electricity; more preferably, the green electricity is green electricity generated in at least one of the forms of light, wind, water, and nuclear energy.

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