Energy-saving environment-friendly self-pumping oxygen measuring probe for optimizing combustion of industrial boiler

Abstract

The invention relates to an energy-saving and environment-friendly self-pumping type oxygen measuring probe for optimizing combustion of an industrial boiler, which comprises a zirconium oxide measuring element, a stainless steel protective cover, a ceramic thermal insulation layer, a ceramic electric heater, a temperature thermocouple and the like, one end of the zirconium oxide measuring element is closed, the other end of the zirconium oxide measuring element is of an open structure, a measuring electrode and a reference electrode are arranged at corresponding positions of the inner wall and the outer wall of the middle section of the zirconium oxide measuring element, a reference gas heat convection channel and a measured gas measuring channel are arranged in the measuring system, and when gases with different oxygen concentrations pass through the inner side and the outer side of the zirconium oxide measuring element, electromotive force is generated. The ceramic filter can prevent dust and impurities in the flue gas from scouring and corroding the measuring electrode and causing aging and falling of the measuring electrode, and also has a damping effect on the measured gas, so that the flow of the reference gas and the flow of the measured gas are relatively consistent, and the standard and the requirement of the zirconium oxide oxygen measurement technology on the gas flow are met.

Description

Technical Field

[0001] This invention relates to a measuring device in a zirconia oxygen analyzer, specifically to a self-extracting oxygen measuring probe. Background Art

[0002] Zirconia oxygen measurement technology has been widely applied in various fields, including coal-fired, oil-fired, and gas-fired boilers and other industrial kilns. The zirconia oxygen analyzer is a specialized instrument for detecting the excess air content in flue gas during boiler fuel combustion. It has significant economic and social benefits for optimizing combustion, controlling production processes, and reducing air pollution. During boiler operation, heat loss mainly occurs in four areas: flue gas loss, incomplete combustion loss, incomplete carbon combustion loss, and heat dissipation loss. Flue gas loss is the primary loss. For example, in a coal-fired boiler with a combustion efficiency of 75%, of the 25% heat loss, flue gas loss and incomplete combustion account for the largest share, approximately 18%. Incomplete combustion of carbon accounts for approximately 3%, and heat loss is approximately 4%. Therefore, using an oxygen analyzer to control the air / fuel ratio to optimize combustion, reduce flue gas losses, and prevent air pollution is a primary method for protecting the environment and improving thermal efficiency. During boiler combustion, when the excess air oxygen content is too low (i.e., insufficient oxygen), although flue gas losses are reduced, incomplete combustion increases carbon monoxide content, resulting in incomplete chemical and mechanical combustion, causing heat loss and reducing combustion efficiency. This wastes fuel and produces large amounts of black smoke, causing air pollution and severely impacting the environment. Conversely, when the excess air oxygen content is too high, although incomplete combustion losses are reduced, the excess air carries... The heat lost will escape through the chimney, increasing flue gas losses and reducing thermal efficiency. Furthermore, the excessive oxygen, nitrogen, and sulfur at high temperatures generate toxic nitrogen oxides, causing environmental pollution and severe corrosion at the boiler tail section. To achieve high boiler combustion thermal efficiency, reduce environmental pollution, and lower harmful gases in the flue gas, the excess oxygen content must be controlled within an appropriate range. This is achieved by using a zirconia oxygen analyzer to optimize combustion, thereby achieving energy conservation and environmental protection. The core component of the oxygen analyzer is the measuring probe. The measuring element in the probe becomes a stable solid electrolyte that can only conduct oxygen ions at high temperatures. Porous platinum or silver electrodes are attached to both sides of the electrolyte. When the electrolyte... When different concentrations of oxygen pass through the flue gas, charge accumulates on both surfaces, creating a potential difference known as the concentration cell electromotive force (EMF). The magnitude of this EMF depends solely on the oxygen concentration in the gases on both sides. After conversion, this EMF directly reflects the oxygen content in the flue gas. Currently, the commonly used measurement method is a constant-temperature direct-insertion method, where the oxygen measurement probe is directly inserted into the outlet of the high-temperature economizer through a protective sleeve. The flue gas then contacts the electrode layer of the zirconia measuring element through the probe. However, due to unreasonable sampling methods and defects in the probe structure, the accuracy and reliability of the measurement results are directly affected, failing to meet the needs of optimized combustion, energy saving, and environmental protection.

[0003] Summary of the Invention: In order to overcome the unreasonableness of the gas sampling system and the structural defects of the measuring probe, the present invention aims to provide a self-extracting zirconia oxygen measuring probe.

[0004] The technical solution adopted in this invention includes a self-extracting zirconia oxygen measurement probe comprising a stainless steel protective cover, a ceramic filter, an aluminum silicate insulation layer, a zirconia measuring element, and a temperature-sensing thermocouple. The zirconia measuring element has a U-shaped tubular structure with inner and outer electrodes positioned correspondingly on its inner and outer walls. A dual ceramic electric heater is located on the outside of the zirconia measuring element, and the temperature-sensing thermocouple is located at the center of the reference electrode inside the measuring element. The outer side of the zirconia measuring element consists, in sequence, a ceramic filter, an aluminum silicate insulation layer, a ceramic heat insulation layer, a stainless steel protective cover, and the measuring probe itself contains a reference gas (air) thermal convection channel and a working channel for the measured gas. Figure 1 As indicated by the arrows, the flue gas sampling at the inlet of the bypass flue should ensure that the measured gas in the flue gas after fuel combustion is representative. According to requirements, the inlet of the bypass flue should be located at the outlet of the high-temperature economizer. The insertion depth of the bypass flue into the outlet flue of the high-temperature economizer is crucial; it not only reflects the accuracy of the measurement results but also provides a basis for optimizing combustion. The optimal insertion depth of the bypass flue sampling tube is the center of the diagonal of the rectangular cross-section of the outlet flue of the high-temperature economizer. Generally, bypass flues A and B are set up, and two sets of zirconia oxygen analyzers are installed. The sampling device in the flue should be selected by directly connecting the bypass flues A and B with steel pipes. The steel pipes are drilled with regularly spaced honeycomb holes. The rapidly flowing flue gas in the flue enters the connecting pipe directly through the honeycomb holes. This invention uses a ceramic electric heater for heating. When the operating temperature is 700 degrees Celsius, the reference gas inside the zirconia measuring element flows naturally under the effect of thermal convection. Outside the zirconia element, the gas to be measured enters the gas measurement channel after being filtered by a ceramic filter to remove dust and impurities. This ensures that the gas flow rates of the gas to be measured and the reference gas are relatively consistent within the channel. When gases with different oxygen concentrations pass between the inner and outer zirconia elements, an electromotive force will be generated between the electrodes. The magnitude of the electromotive force is related to the oxygen content in the two gases. By measuring the oxygen content in the flue gas and controlling the production process, the combustion efficiency can be maximized.

[0005] This invention has the following advantages: It has a reasonable structure and strong practicality. The ceramic filter has a damping effect on the gas being measured, significantly reducing the smoke pressure of the gas after the filter. This ensures that the flow rates of the measured gas and the reference gas are relatively consistent, meeting the specifications and requirements for gas flow rates in zirconia oxygen measurement technology. This facilitates obtaining accurate measurement results. The ceramic filter also removes dust and impurities from the measured gas, preventing erosion and corrosion of the measuring electrodes, which could lead to electrode performance deterioration and measurement errors. The oxygen measurement probe, composed of a zirconia measuring element, a ceramic electric heater, a ceramic insulation layer, a thermocouple, and an adjustable probe length support tube, works well together to ensure the measuring element operates within a stable temperature field, meeting the requirements for measurement conditions. This results in more accurate and reliable measurement results, faster response times, and is beneficial for optimizing combustion and meeting energy-saving and environmental protection needs. Attached Figure Description Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention. In the diagram: 1. Ceramic filter 2. Stainless steel protective cover 3. Ceramic insulation layer 4. Aluminum silicate insulation layer 5. Ceramic electric heater 6. Measuring electrode lead hole 7. Gas measuring chamber 8. Zirconia measuring element 9. Reference electrode 10. Thermocouple 11. Measuring electrode 12. Measured gas measuring channel 13. Adjustable probe length support tube 14. Reference gas outlet 15. Gas three-way valve 16. Standard gas shut-off valve 17. Standard gas cylinder 18. Reference gas thermal convection inlet 19. Junction box 20. Measured gas outlet 21. Measuring pipeline expansion container 22. Fixed flange Detailed Description of Embodiments: The embodiments of the present invention will be further described below with reference to the accompanying drawings. Example 1. Figure 1As shown, the present invention discloses an industrial boiler optimized combustion, energy-saving, and environmentally friendly self-extracting oxygen measurement probe. The probe comprises a zirconium oxide measuring element 8, a ceramic electric heater 5, a ceramic insulation layer 3, an aluminum silicate insulation layer 4, a temperature measuring thermocouple 10, and an adjustable probe length support tube 13, all working in harmony. The heater is a double-layer ceramic electric heater 5, which has high insulation strength, is easy to install, and heats up quickly. The inner and outer walls of the ceramic insulation layer 3 are coated with an insulation material, and the middle layer is a porous ceramic air insulation layer, the purpose of which is to increase... Thermal resistance enhances the heat insulation effect, ensuring a stable environment for the zirconia measuring element and contributing to the accuracy of measurement results. The reference gas thermal convection channel includes: reference gas (air) enters through the thermal convection inlet hole 18, flows along the inner lower wall of the support tube 13 along the probe length adjustment, enters the inner side of the zirconia measuring element 8, and after passing through the heating zone, the reference gas forms thermal convection efficiency, flows along the inner upper wall of the support tube 13, and exits through the thermal convection outlet hole 14, forming the reference gas thermal convection channel. The measured gas flow channel includes: the measured gas passes through the ceramic filter 1... Entering the gas measurement chamber 7, the gas to be measured travels along the outer side of the zirconia measuring element 8, contacts the surface of the measuring electrode 11, and then enters the gas measurement channel 12. The negative pressure generated by the gas outlet pipe 20 draws the gas out. When the gas is flowing, the gas three-way valve should be in the straight-through position. When the measuring probe is being calibrated, the gas three-way valve 15 is switched from the straight-through to the bypass position. The standard gas shut-off valve 16 is adjusted so that the standard gas cylinder 17 enters the measuring probe at a gas flow rate of 300 mL / min. The temperature measuring thermocouple 10 and ceramic... The leads of the ceramic electric heater 5 and the zirconia measuring element 8 are connected to the junction box 19. Due to the structural requirements of the measuring probe, the measuring leads of the measuring electrode need to be connected through the measuring electrode lead hole. The upper inlet of the bypass flue expansion container 21 should be connected to the center of the diagonal of the rectangular section inside the high-temperature economizer outlet flue. The probe length adjustable support pipe 13 is connected to the fixed flange 22. When the measurement conditions meet the requirements of the measuring probe, the measurement results are accurate and reliable, and the response time is faster, which is conducive to optimizing combustion, saving energy and protecting the environment.

[0006] In this embodiment, the operating temperature is 700±10 degrees Celsius, heated by a ceramic electric heater 5. A thermocouple measures the temperature, and the result is transmitted to the control unit. The control unit amplifies and adjusts the temperature to ensure the measuring element 8 in the probe is within a stable operating temperature field. Inside the zirconia measuring element 8, reference gas (air) at room temperature enters through the thermal convection inlet 18, flows along the lower inner wall of the adjustable support tube 13, and enters the zirconia measuring element. After passing through the heating zone, the reference gas flows out through the thermal outlet 14 along the upper inner wall of the adjustable support tube 13, forming a natural flow of reference gas. The gas to be measured enters the measuring element through the ceramic filter 1. After the outer side of the zirconia measuring element 8 contacts the surface of the measuring electrode 11 in the measuring chamber 7, it enters the gas measuring channel 12. The negative pressure generated by the gas outlet pipe 20 draws out the gas, allowing it to flow. During operation, when gases of different oxygen concentrations pass through the inner and outer sides of the zirconia measuring element 8, an electromotive force will be generated between the inner and outer electrodes. The magnitude of the electromotive force is related to the oxygen content in the gas on both sides of the zirconia measuring element 8. By detecting the oxygen content of the gas in the flue gas, the combustion conditions of the industrial boiler can be understood in a timely manner. Based on the oxygen content of the gas, the operating equipment can be corrected in a timely manner to obtain the optimal excess air oxygen value.

Claims

1. An energy-saving and environmentally friendly self-extracting oxygen measurement probe for optimized combustion in industrial boilers includes a stainless steel protective cover 2, a ceramic filter 1, a zirconia measuring element 8, a temperature measuring thermocouple 10, a double-layer ceramic electric heater 5, an adjustable probe length support tube 13, and a ceramic insulation layer 3, characterized in that... The zirconia measuring element 8 is a U-shaped tube, closed at one end and open at the other. Reference electrode 9, measuring electrode 11, and ceramic electric heater 5 are respectively provided on the inner and outer walls. On the outside of the zirconia measuring element 8, there are aluminum silicate insulation layer 4, ceramic heat insulation layer 3, stainless steel protective cover 2, and probe length adjustable support tube 13. Reference gas thermal convection inlet hole 18 and reference gas thermal convection outlet hole 14 are respectively provided on the upper and lower sides, which can form a reference gas convection channel. The gas to be measured enters the gas measuring chamber 7 through the ceramic filter 1, and after contacting the surface of the measuring electrode 11 of the zirconia measuring element 8, it enters the gas measuring channel 12 and is extracted by the negative pressure generated by the gas outlet pipe 20, forming the gas measuring channel.

2. The industrial boiler optimized combustion, energy saving, and environmental protection self-extracting oxygen measurement probe according to claim 1 or 2, characterized in that... The gas measurement channel 12.

3. The industrial boiler optimized combustion, energy saving, and environmental protection self-extraction oxygen measurement probe according to claim 1 or 2, characterized in that... The probe length is adjustable support tube 13.

4. The industrial boiler optimized combustion, energy saving, and environmental protection self-extracting oxygen measurement probe according to claim 1 or 2, characterized in that... The ceramic heat insulation layer 3.

5. The industrial boiler optimized combustion, energy saving, and environmental protection self-extracting oxygen measurement probe according to claim 1 or 2, characterized in that... The double-layer ceramic electric heater 5.

6. The industrial boiler optimized combustion, energy saving, and environmental protection self-extraction oxygen measurement probe according to claim 1 or 2, characterized in that... The reference gas measurement channel has an inlet hole 18 and an outlet hole 14.

7. The industrial boiler optimized combustion, energy saving, and environmental protection self-extraction oxygen measurement probe according to claim 1 or 2, characterized in that... The outlet pipe 20 of the gas being measured in the gas ejection method.

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