Method for measuring oxygen content in combustion air

Abstract

The application discloses a method for measuring and calculating oxygen content in combustion-supporting air. Under the premise that the gas composition and volume fraction, and the CO2 volume fraction of dry flue gas are known, the flue gas volume is obtained according to the CO2 volume, the H2O volume and the CO2 volume fraction of dry flue gas. The N2 amount carried by the combustion-supporting gas is calculated according to the flue gas volume. According to the calculation that the air is mainly composed of oxygen and nitrogen, the oxygen volume fraction in the combustion-supporting gas can be obtained through analysis and calculation. The method realizes the reduction of energy consumption and the improvement of combustion efficiency, and promotes the popularization and application of energy-saving and carbon-reducing technologies such as oxygen-rich combustion.

Description

Technical Field

[0001] This invention belongs to the field of industrial combustion technology, specifically relating to a method for calculating the oxygen content in combustion air. Background Technology

[0002] In industrial combustion processes, controlling the oxygen concentration in the combustion air is crucial for improving combustion efficiency, reducing emissions, and saving energy. Traditional methods for calculating oxygen enrichment typically rely on a single parameter or a simple model, lacking consideration for the complexity of the combustion process, which limits the accuracy of the calculation results.

[0003] Chinese invention patent (authorization announcement number CN104791777B) discloses a combustion method for reducing NOx using flue gas self-circulation. This method achieves low NOx combustion by recirculating the flue gas discharged from the furnace back into the system. Specifically, a portion of the flue gas discharged from the regenerator system is extracted to dilute the combustion air and gas, reducing their concentrations and creating high-temperature, oxygen-deficient combustion conditions before the gases enter the burner. Through flue gas self-circulation and quantitative control of the mixing ratio, the calorific value of the fuel gas, the oxygen content of the air, and the combustion atmosphere in the furnace can be controlled, improving the stability of the regenerator combustion system and its applicability to wider furnace sizes. However, the lack of consideration for the complexity of the combustion process limits the accuracy of the calculation results. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for calculating the oxygen content in combustion air to reduce energy consumption and improve combustion efficiency.

[0005] To achieve the above objectives, the present invention provides a method for calculating the oxygen content in combustion air:

[0006]

[0007] in, This represents the volume fraction.

[0008] Furthermore, the oxygen volume fraction The derivation process is as follows:

[0009] Under conditions of an air-fuel ratio α of 1, complete combustion of coal gas, and no residual oxygen in the flue gas, according to the ideal gas law and the law of conservation of mass, the combustion process involves H2, CH4, CO, and C. n H m After complete combustion, the gases are converted into CO2 and H2O respectively. The N2 in the flue gas comes partly from the coal gas and partly from the combustion-supporting gases. Therefore:

[0010]

[0011] Furthermore, the online gas monitoring system of the calculation method includes a combustion reactor, a gas branch pipe connected to the burner at the top of the combustion reactor, an air branch pipe connected to the burner at the top of the combustion reactor, and a main flue gas pipe connected to the flue gas outlet of the combustion reactor. A gas analyzer is arranged on the gas branch pipe, and a flue gas analyzer is arranged on the main flue gas pipe.

[0012] Furthermore, the gas branch pipe is equipped with a gas branch pipe electric regulating valve and a gas branch pipe flow meter, and the air branch pipe is equipped with an air branch pipe electric regulating valve and an air branch pipe flow meter.

[0013] Furthermore, the gas branch pipe electric regulating valve, the gas branch pipe flow meter, the air branch pipe electric regulating valve, and the air branch pipe flow meter are all connected to the data acquisition and processing system via data cables.

[0014] Furthermore, both the flue gas analyzer and the coal gas analyzer are connected to the data acquisition and processing system via data cables.

[0015] Furthermore, adjust the opening degree of the electric regulating valves for the gas branch pipe and the air branch pipe to ensure that the furnace is in an ideal combustion state:

[0016] The flue gas O2 < 0.2% and CO < 50ppm. Take the measured value of CO2 in the dry flue gas at this time.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: by dynamically monitoring the composition of dry-based coal gas and the CO2 content in the dry flue gas produced under ideal combustion conditions (the oxygen content in the flue gas is 0 and there are no air-fuel substances), the oxygen content in the combustion air can be directly calculated, thereby reducing energy consumption and improving combustion efficiency, and promoting the application of energy-saving and carbon-reducing technologies such as oxygen-enriched combustion. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the online gas monitoring system of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments to facilitate a clearer understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0020] Given the composition and volume fraction of the combustion gas, and the volume fraction of CO2 in the dry flue gas, the flue gas volume is obtained based on the volume of CO2, the volume of H2O, and the volume fraction of CO2 in the dry flue gas. The amount of N2 introduced by the combustion-supporting gas is then calculated from the flue gas volume. Assuming that air is primarily composed of oxygen and nitrogen, the oxygen volume fraction in the combustion-supporting gas can be calculated through analysis. The specific calculation method is as follows:

[0021]

[0022] in, This represents the volume fraction.

[0023] oxygen volume fraction The derivation process is as follows:

[0024] Under conditions of an air-fuel ratio α of 1, complete combustion of coal gas, and no residual oxygen in the flue gas, according to the ideal gas law and the law of conservation of mass, the combustion process involves H2, CH4, CO, and C. n H m After complete combustion, the gases are converted into CO2 and H2O respectively. The N2 in the flue gas comes partly from the coal gas and partly from the combustion-supporting gases. Therefore:

[0025]

[0026]

[0027] By dynamically monitoring the composition of dry-based coal gas and the CO2 content in the dry flue gas produced under ideal combustion conditions (zero oxygen content in the flue gas and no air-fuel substances), the oxygen content in the combustion air can be directly calculated, thereby reducing energy consumption and improving combustion efficiency.

[0028] The online gas monitoring system for the calculation method includes a combustion reactor 1, a gas branch pipe 3 connected to the burner 2 at the top of the combustion reactor 1, an air branch pipe 6 connected to the burner 2 at the top of the combustion reactor 1, and a main flue gas pipe 9 connected to the flue gas outlet of the combustion reactor 1. A gas analyzer 10 is installed on the gas branch pipe 3, and a flue gas analyzer 11 is installed on the main flue gas pipe 9. A gas branch pipe electric regulating valve 4 and a gas branch pipe flow meter 5 are installed on the gas branch pipe 3, and an air branch pipe electric regulating valve 7 and an air branch pipe flow meter 8 are installed on the air branch pipe 6. The gas branch pipe electric regulating valve 4, the gas branch pipe flow meter 5, the air branch pipe electric regulating valve 7, the air branch pipe flow meter 8, the flue gas analyzer 11, and the gas analyzer 10 are all connected to the data acquisition and processing system 12 via data cables.

[0029] The heating furnace ensures complete combustion of the coal gas, heats the materials inside, and maintains a furnace temperature of 1000–1300℃ and a furnace pressure of slightly positive pressure (10–20 Pa). The online coal gas monitoring system primarily detects components such as O2, CO, and CO2 in the dry coal gas, and adjusts the opening of the electric regulating valve 4 in the coal gas branch pipe and the electric regulating valve 7 in the air branch pipe to ensure ideal combustion conditions inside the furnace.

[0030] The flue gas O2 < 0.2% and CO < 50ppm. Take the measured value of CO2 in the dry flue gas at this time.

[0031] Example

[0032] dry gas composition

[0033]

[0034] Dry flue gas components

[0035]

[0036] When the oxygen volume fraction is 18%, the flue gas contains

[0037] Conversely, when flue gas is generated, the flue gas contains... When it is 8.71%:

[0038]

Claims

1. A method for calculating the oxygen content in combustion air, characterized in that: in, It is the volume fraction; These represent the volume fraction of CO and C in dry coal gas, respectively. n H m Volume fractions of CO2, CH4, N2, H2, and O2; The volume fraction of O2 in the combustion-supporting air, This represents the volume fraction of CO2 in the dry flue gas after the combustion of dry coal gas. oxygen volume fraction The derivation process is as follows: Under conditions of an air-fuel ratio α of 1, complete combustion of coal gas, and no residual oxygen in the flue gas, according to the ideal gas law and the law of conservation of mass, the combustion process involves H2, CH4, CO, and C. n H m After complete combustion, the gases are converted into CO2 and H2O respectively. The N2 in the flue gas comes partly from the coal gas and partly from the combustion-supporting gases. Therefore:

2. The method for calculating the oxygen content in combustion air according to claim 1, characterized in that: The online gas monitoring system of the calculation method includes a combustion reactor (1), a gas branch pipe (3) connected to the burner (2) at the top of the combustion reactor (1), an air branch pipe (6) connected to the burner (2) at the top of the combustion reactor (1), and a flue gas main pipe (9) connected to the flue gas outlet of the combustion reactor (1). A gas analyzer (10) is arranged on the gas branch pipe (3), and a flue gas analyzer (11) is arranged on the flue gas main pipe (9).

3. The method for calculating the oxygen content in combustion air according to claim 2, characterized in that: The gas branch pipe (3) is equipped with a gas branch pipe electric regulating valve (4) and a gas branch pipe flow meter (5), and the air branch pipe (6) is equipped with an air branch pipe electric regulating valve (7) and an air branch pipe flow meter (8).

4. The method for calculating the oxygen content in combustion air according to claim 2, characterized in that: The gas branch electric regulating valve (4), gas branch flow meter (5), air branch electric regulating valve (7) and air branch flow meter (8) are all connected to the data acquisition and processing system (12) via data cables.

5. The method for calculating the oxygen content in combustion air according to claim 2, characterized in that: Both the flue gas analyzer (11) and the coal gas analyzer (10) are connected to the data acquisition and processing system (12) via data cables.

6. The method for calculating the oxygen content in combustion air according to claim 3, characterized in that: Adjust the opening of the gas branch pipe electric regulating valve (4) and the air branch pipe electric regulating valve (7) to ensure that the furnace is in an ideal combustion state: The flue gas O2 < 0.2% and CO < 50ppm. Take the measured value of CO2 in the dry flue gas at this time.

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