JPS6020649B2 - Required air amount control device for gaseous fuel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for controlling the amount of air required for gaseous fuel, which continuously controls and measures the amount of air required for gaseous fuel using an oxygen detector made of a solid electrolyte.

In general, in various combustion devices that use thermal energy by mixing fluid fuel with air and combusting it, the flow rates of fuel and air are set at a certain ratio prior to combustion in order to use the fuel effectively. Combustion devices that use a so-called air-fuel ratio control mechanism that then combusts, and combustion devices that use a mechanism that measures the oxygen concentration in the combustion exhaust gas and controls the air-fuel ratio by feeding back this signal are widely known. There is.

However, the former has the disadvantage that if the composition of the fuel varies, an error occurs in the air-fuel ratio, resulting in excess air or, conversely, excess fuel, making it extremely difficult to perform proper combustion. In addition, the latter has the same drawbacks as the former, such as a large response delay in gas sampling and fuels whose composition changes. In order to solve this problem, conventional gaseous fuel compositions such as CH4, C4, o
, &, C○, etc. in the gaseous fuel are individually analyzed by gas chromatography, and from the results, the amount of air required for proper combustion of the gaseous fuel according to the analyzed composition is calculated, and the combustion Combustion devices that perform proper combustion by adjusting the amount of air supplied to the device are also known. However, since analysis time using gas chromatography takes a long time, approximately 1 hour, feeding this back online is only applicable when the fuel composition is relatively stable, and the analysis time is only suitable for gaseous fuels whose composition changes constantly. Until now, almost no measures have been taken regarding combustion, and there have been many problems in terms of fuel consumption and exhaust gas countermeasures. The required air amount control device for gaseous fuel of the present invention not only solves these conventional drawbacks and problems, but also produces gaseous fuel with a stable composition.
This device can quickly and continuously control and measure the amount of air required for gaseous fuel whose composition is constantly changing.

The present invention provides: - a gas mixer that mixes a constant flow rate of gaseous fuel and air; a mixed gas constant flow device that makes the mixed gas discharged from the gas mixer a constant flow rate; and the mixed gas constant flow device. An oxygen detector consisting of a solid electrolyte that detects the residual oxygen concentration in the combustion exhaust gas while burning the mixed gas at a constant flow rate in a high-temperature combustion zone, and an electromotive force E corresponding to the oxygen concentration from the oxygen detector. , and a reference voltage E2 corresponding to a preset reference oxygen concentration. It consists of at least an air flow controller inserted into the air introduction path to control the amount of air remaining in the combustion exhaust gas, and an air flow meter that measures the constant flow rate of air controlled by the air flow controller. The amount of air required for combustion is measured and controlled so that the concentration matches the standard oxygen concentration set in advance, and the amount of air required for gaseous fuel is measured before the gaseous fuel is combusted in the combustion device. A device for controlling the amount of air required for gaseous fuel is characterized by controlling an air flow rate controller.

The configuration will be explained below with reference to the drawings showing one embodiment.

In FIG. 1, the gaseous fuel 28 enters from the sample gas inlet 1, is sucked in by the sample gas sampling pump 2 and raised to a constant pressure or higher, and then passes through the sample gas constant flow meter 3 to maintain a constant flow rate and constant pressure. The gas is introduced into the gas mixer 7. On the other hand, pressurized air 271 enters from the air inlet 4, is controlled in flow rate by the air flow controller 5, and is then introduced into the gas mixer through the air flow meter 6. After a certain amount of gaseous fuel and air are thoroughly mixed in a gas mixer 7, they are branched into two branches, one of which is made into a constant flow rate by a mixed gas constant flow device 8, and then separated from a cylindrical solid electrolyte having a high-temperature combustion zone. At the same time, the combustion exhaust gas is completely combusted in the oxygen detector 9, and an electromotive force E corresponding to the residual oxygen concentration in the combustion exhaust gas is detected. After being burned in a suitable combustion furnace via a gas flow divider regulator 10, it is discharged from an outlet port 1.The mixed gas constant flow meter 8 is configured so that even if the flow rate changes, the oxygen detector 9 detects fluctuations in the gas flow rate. As shown in FIG. 900-1 with a catalyst bed 17 made of platinum and porous porcelain on the mixed gas inlet 16 side
The high temperature zone 8 of 500 mm and the low temperature zone 28 of 600 to 900 mm, in which the electromotive force E corresponding to the residual oxygen concentration in the combustion exhaust gas is obtained using the electrodes 19 and 2, are the heating wires 22 and 28, respectively. It is heated and maintained at a predetermined temperature at 23. Therefore, a constant flow rate of the mixed gas from the mixed gas constant flow meter 8 is introduced into the oxygen detector 9 through the mixed gas inlet 16, and is first completely combusted in the catalyst bed 17 of the high temperature zone 18, and then the combusted sample gas is In the low temperature zone 281, an electromotive force E corresponding to the residual oxygen concentration in the combustion gas is generated between the standard gas introduced from the standard gas inlet 24 to the outside of the cylindrical solid electrolyte due to ion conduction. Electrodes 19, 20
1 is generated, and the electromotive force E,' is transmitted to the oxygen concentration setting device 12 by the lead wires 25 and 26. In this case, the relationship between oxygen concentration and electromotive force in the cylindrical solid electrolyte is 0.
It is shown in equation 1. E,=St. g groove [mV] …o'
Here, E,: electromotive force, R: gas constant, T: absolute temperature,
F: Fade constant, cPo2: oxygen concentration at the cathode side electrode ~ aPo2: oxygen partial pressure at the front side electrode.

Now, if we keep aPo2 constant here, E, then cPo
2 is required. Therefore, if the oxygen concentration in the mixed gas and the oxygen equivalent concentration of the combustible component are mPo2 and x, respectively, the combustible component is burned in the high temperature zone, so the electromotive force of the oxygen detector 9 is E, : zone.

G home to X [mV].・It becomes a cape.

Here, E is an electromotive force corresponding to the oxygen concentration in the combustion exhaust gas, and a reference voltage 2 corresponding to the reference oxygen concentration is obtained. The oxygen concentration setting device 12, which receives an electromotive force E corresponding to the oxygen concentration in the exhaust gas through the lead wires 25 and 26, has a built-in reference voltage E2 corresponding to a certain predetermined oxygen concentration, that is, a reference oxygen concentration. E2 and E are compared, and an electrical signal proportional to the difference is generated.The electrical signal is transmitted to the signal converter 13, where it is used to drive the air flow controller 5. The signal is converted into another appropriate signal to control the air flow rate controller 5, and at the same time, the air flow rate is measured and indicated by the air flow meter 6. For example, if you want to find the required amount of air so that the residual oxygen concentration in the combustion exhaust gas of a certain gaseous fuel is 1%, first, set the reference voltage tile 2 corresponding to the reference oxygen concentration of the oxygen concentration setting device 12 to 1%. Set the voltage corresponding to %. If the composition changes and the combustible content of the gaseous fuel increases, the residual oxygen concentration in the combustion exhaust gas will naturally decrease.
The air flow rate is automatically increased, and when the combustible content of the gaseous fuel is low, the air flow rate is automatically reduced to keep the residual oxygen concentration in the combustion exhaust gas consistent with the standard oxygen concentration. The air volume is automatically controlled and measured. Therefore,
Even if the composition of the gaseous fuel changes, that is, the required amount of air changes, the air flow rate is automatically controlled and measured so that the oxygen concentration in the combustion exhaust gas matches the reference oxygen concentration, and the amount of air is adjusted to match the gaseous fuel. This system quickly and continuously controls and measures the amount of air required. Then, stable combustion in the burner can be ensured by controlling the combustion device air controller 30 that controls the flow rate of the combustion air 29 supplied to the burner 31 of the combustion device 32 based on the measured required air amount signal. It is.

Next, a specific example using the control device of the present invention will be described.

For the combustible component, C, prepare various sample gases containing CO and CO, analyze each of the above combustible components by gas chromatography, and calculate the required air amount from the analysis results (theoretical air amount). The comparison result between the value converted to the stoichiometric air-fuel ratio (amount/fuel amount) and the measured value measured using the device of the present invention is as shown in Figure 3, and the two values almost match. . In addition, it was confirmed that the results of long-term continuous measurements using a sample gas with a stoichiometric air-fuel ratio of 3.4 using the device of the present invention were stable with almost no change over time observed due to the blockage in Figure 4. It was done.

Furthermore, two types of sample gases with stoichiometric air-fuel ratios of 1.5 and 8.0 were alternately flowed through this device, and the response time of the command was investigated. The results are shown in Figure 5, and the response time from the time when the command changed It was also confirmed that the time required to reach a value of 90% of full scale was about 19 seconds, and that the device of the present invention had extremely fast response. As described above, the device for controlling the amount of air required for gaseous fuel of the present invention can quickly control and measure the amount of air even for gaseous fuel whose composition changes significantly, and is suitable for controlling gaseous fuel in steel manufacturing, electric power, and petrochemical plants. By installing it in the fuel pipes of various combustion devices or boilers to be used, it is possible to extremely quickly set the most appropriate amount of air for gaseous fuel, improving thermal efficiency, reducing fuel consumption, and improving exhaust gas countermeasures. This is an extremely useful device industrially.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the required air amount control device for gaseous fuel of the present invention, FIG. 2 is an explanatory diagram showing a cross section of an oxygen detector in the control device of the present invention, and FIGS. 3 to 5 are FIG. 3 is an explanatory diagram of measurement results according to a specific example using the device of the present invention. -1...Sample gas inlet, 2...Sample gas sampling pump, 3...Sample gas constant flow meter, 4...
... Air inlet, 5 Air flow rate controller, 6... Air flow meter, 7... Gas mixer, 8 Mixed gas constant flow meter, 9
...Oxygen detector, 10...Mixed gas separation regulator, 11...Gas outlet, 12...Reference oxygen concentration setting device 13... Signal converter, 14...
・・・Solid electrolyte cylinder, 15...Electric furnace, 16...
...Mixed gas inlet, 17...Catalyst bed, 18...High temperature zone, 19,20...Electrode, 21...Low temperature zone, 22,23...Heating wire , 24... Standard gas inlet, 25, 26... Lead wire, 27
..... Pressurized air, 28 ..... Gaseous fuel, 2
9... Combustion air, 30... Combustion device air controller, 31... Burner ~ 32... Combustion device. Figure 1 Figure 2 Figure 4 Figure 3 Figure 5

Claims (1)

[Claims] 1. A gas mixer that mixes a constant flow rate of gaseous fuel and air, a mixed gas constant flow device that makes a constant flow rate of the mixed gas discharged from the gas mixer, and a constant flow rate of the mixed gas. An oxygen detector consisting of a solid electrolyte that burns a constant flow of mixed gas in a high-temperature combustion zone and detects the concentration of residual acid in the combustion exhaust gas, and an electromotive force corresponding to the oxygen concentration from the oxygen detector. Combustion air is controlled to the above-mentioned constant level by an oxygen concentration setting device that outputs an electric signal proportional to the difference between E_1 and a reference voltage E_2 corresponding to a preset reference oxygen concentration, and an electric signal output from the oxygen concentration setting device. an air flow controller inserted into the air introduction path to control the flow rate of the air;
It consists of at least an air flow meter that measures the amount of air at a constant flow rate controlled by the air flow controller, and measures the amount of air necessary for combustion so that the residual oxygen concentration in the combustion exhaust gas matches a preset reference oxygen concentration. Control of the required air amount of gaseous fuel, characterized in that the amount of air required for the gaseous fuel is measured and controlled before the gaseous fuel is combusted in the combustion device, and an air flow rate controller for the combustion device is controlled based on the measurement result. Device. 2. The oxygen detector includes a solid electrolyte cylinder, an electric furnace surrounding the solid electrolyte cylinder and having a high temperature zone on the inlet side and a low temperature zone on the outlet side, and a solid electrolyte in the high temperature zone of the electric furnace. It consists of a catalyst bed installed in a cylinder and electrodes installed inside and outside the solid electrolyte cylinder located in the low-temperature zone, and burns a fixed amount of mixed gas in the high-temperature combustion zone, and reduces the residual oxygen concentration in the combustion exhaust gas. 2. The required air amount control device for gaseous fuel according to claim 1, which is configured to detect the amount of air by means of electrodes provided inside and outside the low temperature zone.