CN211176783U - Natural gas combustion closed-loop control system - Google Patents
Natural gas combustion closed-loop control system Download PDFInfo
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- CN211176783U CN211176783U CN201921856406.4U CN201921856406U CN211176783U CN 211176783 U CN211176783 U CN 211176783U CN 201921856406 U CN201921856406 U CN 201921856406U CN 211176783 U CN211176783 U CN 211176783U
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Abstract
A natural gas combustion closed-loop control system comprises a control system, a combustor, a proportion regulating valve, a fan, a wind pressure sensor and a zirconia oxygen sensor; the proportion regulating valve is arranged at the gas inlet; the air inlet is communicated with the fan; the zirconia oxygen sensor is arranged at the tail part of the combustor or on the smoke exhaust pipeline and is electrically connected with the control system; the wind pressure sensor and the wind pressure switch are arranged at the air inlet; the wind pressure sensor, the proportion regulating valve and the fan are electrically connected with the control system. The utility model discloses can guarantee that gas and air mix the homogeneous combustion completely abundant to can improve zirconia oxygen sensor validity and reliability in signal transmission process greatly, more accurate detection discharges, accomplishes energy-concerving and environment-protective improvement combustion efficiency.
Description
Technical Field
The utility model relates to a burning technical field specifically is a natural gas burning closed-loop control system.
Background
The combustion system is a combination of equipment and corresponding smoke, wind and coal (coal powder) pipelines, which are required for enabling fuel to be fully combusted in a boiler hearth and discharging smoke generated by combustion into the atmosphere. The task of the combustion system is to convert the chemical energy contained in the fuel into heat energy that can be absorbed by the steam and water by combustion. Therefore, the quality of the combustion system will directly affect the thermal efficiency of the boiler. The combustion efficiency depends on the mixing state of the combustible and the comburent. Currently, combustion devices generally employ various regulating valves or devices to control the supply of fuel and air in a certain proportion, and then mix and burn in a combustion chamber, which is limited by space (sufficient space is required for diffusion mixing) and time (the combustion speed is matched with the diffusion speed). The premixing technology is characterized in that fuel and air are completely mixed before entering a nozzle of a combustion chamber, and gas molecules are fully stirred and dispersed and mixed through a premixing cavity, so that the mixing is more complete, the combustion speed is not limited by physical conditions such as gas diffusion speed and the like, and the combustion speed is higher and the efficiency is higher.
Traditional combustion methods can not carry out closed-loop control more, and combustion system can only burn according to the mechanical valve aperture of preliminary adjustment, when external operating mode changes, can not respond in time and make the adjustment, leads to combustion efficiency greatly reduced, and the burning inadequately leads to discharging to exceed standard. The full premixing technology is combined with the combustion sensor tail gas detection method, so that complete mixing, uniform combustion and full combustion of gas and air are guaranteed, meanwhile, emission is detected in real time, emission is guaranteed to reach the standard, energy conservation and environmental protection are achieved, and the combustion efficiency is improved.
The combustion sensor tail gas detection method generally utilizes an oxygen sensor to detect tail gas, a zirconia oxygen sensor can be suitable for the environment with the temperature of more than 600 ℃, however, the zirconia oxygen sensor is traditionally applied in a way that a mutation point signal of the zirconia sensor is transmitted to an ECU, and the theoretical air-fuel ratio of fuel oil control is as follows: a/F is 14.7:1, λ is 1. When the mixed gas is thickened, namely the oxygen content in the tail gas is low, the output voltage of the oxygen sensor is close to 1V; when the mixed gas becomes dilute, namely the output signal of the high oxygen content sensor in the tail gas is close to 0V, the ECU judges the emission state according to the sudden change of the signal so as to adjust the opening of the fuel valve, thereby realizing the real-time monitoring of the smoke emission. In a natural gas combustion system, in order to ensure that the emission reaches the standard and the combustion efficiency is high, the air-fuel ratio is controlled to be 21.57:1 through a large amount of experimental test data, lambda is 1.25, the zirconia oxygen sensor is always in an over-lean state, and an output voltage signal is always smaller than 0.45V; it can be seen that there is a great difference between the use of zirconia oxygen sensors in natural gas combustion systems and in fuel oil, mainly expressed as a difference in the target value for controlling the excess air; the output signal of a zirconia oxygen sensor in a natural gas combustion system is weak, and the effectiveness and the reliability of the zirconia oxygen sensor in signal transmission are greatly reduced.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a natural gas burning closed-loop control system can guarantee that gas and air mix the homogeneous combustion completely abundant to can improve zirconia oxygen sensor validity and reliability in signal transmission process greatly, and then form closed-loop control system, more accurate detection emission ensures to discharge up to standard, accomplishes energy-concerving and environment-protective improvement combustion efficiency.
The method for using the zirconia oxygen sensor in the natural gas combustion mainly comprises the steps of utilizing the output voltage of the sensor, transmitting the output voltage signal of the sensor to P L C, judging the oxygen content in the combustion tail gas of the natural gas according to the signal of the oxygen sensor by P L C, and adjusting the opening of a gas valve according to the over-rich and over-lean state, thereby realizing the closed-loop control of the natural gas tail gas emission.
The output signal of the oxygen sensor in the combustion system is weak, so that the output signal of the oxygen sensor needs to be processed to ensure the validity and reliability of the signal, the signal processing mainly comprises signal anti-interference processing and signal amplification, the anti-interference processing mainly adopts a filter capacitor to prevent external alternating current signal interference, meanwhile, an amplifier has a common-mode rejection function, can effectively prevent an external interference source from causing signal distortion, and ensures the reliability and stability of the signal.
The utility model discloses a specific technical scheme is:
a natural gas combustion closed-loop control system comprises a control system, a combustor, a proportion regulating valve, a fan, a wind pressure sensor and a zirconia oxygen sensor;
wherein the burner is respectively communicated with the gas inlet and the air inlet; the proportion regulating valve is arranged at the gas inlet; the air inlet is communicated with the fan; the zirconia oxygen sensor is arranged at the tail part of the combustor or on the smoke exhaust pipeline and is electrically connected with the control system; the wind pressure sensor is arranged at the air inlet; the wind pressure sensor, the proportion regulating valve and the fan are electrically connected with the control system.
Further, the zirconia oxygen sensor is connected with a signal amplifier and a filter.
The gas mixing device further comprises a premixer, wherein an air interface, a gas interface and a mixed gas outlet are arranged on the premixer; the air inlet is communicated with the air interface, and the gas inlet is communicated with the gas interface; the mixed gas outlet is communicated with the burner.
Further, the control system comprises an ignition controller, an igniter and a P L C controller.
The utility model has the advantages that the scheme is that the premixer is the venturi mixer, air inlet does the air inlet of venturi mixer, the gas interface does the induction port of venturi mixer, the mist outlet does the gas outlet of venturi mixer.
Further, the wind pressure switch is further included.
Further, the heating voltage of the zirconia oxygen sensor is preheated by low-voltage DC5V, and the voltage is boosted to DC12V for heating after preheating.
Compared with the prior art, the utility model has the advantages as follows:
1) the utility model has the advantages of full combustion, high combustion efficiency, and the fuel with the same volume can be converted and utilized with a larger proportion of heat energy, thereby saving more energy on the premise of using clean energy; and the effectiveness and the reliability of the zirconia oxygen sensor in the signal transmission process can be greatly improved, a closed-loop control system is further formed, the emission is low, carbon oxides and nitrogen oxides generated by combustion are extremely low, and the environmental protection is remarkably contributed.
2) The utility model discloses but automated inspection ignition deflagration and tempering problem to in time the adjustment, safety when guaranteeing to ignite and catch fire guarantees to ignite stably effectively, improves the operation of system safety and stability.
3) The utility model discloses can realize real-time supervision combustion state, the state of the inside flame burning of accurate judgement furnace body, effectual assurance burning is abundant, in time carries out fault identification, ensures combustion system's safe high-efficient steady operation.
Drawings
Fig. 1 is a schematic structural diagram of a combustion system in an embodiment of the present invention;
FIG. 2 is a control diagram of a combustion system according to an embodiment of the present invention;
fig. 3 is a circuit diagram of a signal amplifier and a filter connected to the zirconia oxygen sensor of the present invention.
In the figure: 1. a control system; 2. a fan; 3. a proportional regulating valve; 4. a burner; 5. a wind pressure sensor; 6. a wind pressure switch; 7. a zirconia oxygen sensor connected with a signal amplifier and a filter; 8. an igniter; 9. a premixer; 10. a gas inlet; 11. an air inlet; 12. a smoke exhaust pipeline.
Detailed Description
The following description is provided for illustrative purposes, and other advantages and features of the present invention will become apparent to those skilled in the art from the following detailed description.
It should be understood that the structures, ratios, sizes, etc. shown in the drawings of the present application are only used for matching with the contents disclosed in the specification, so as to be known and read by those skilled in the art, and are not used for limiting the limit conditions that the present invention can be implemented, so that the present invention has no technical essential meaning, and any modification of the structures, change of the ratio relationship or adjustment of the sizes should still fall within the scope of the present invention without affecting the functions and the achievable purposes of the present invention. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof may be made without substantial technical changes, and the present invention is also regarded as the scope of the present invention.
Example 1
The embodiment discloses a natural gas combustion closed-loop control system, as shown in fig. 2, which includes a control system 1, a burner 4, a proportional control valve 3, a fan 2, a wind pressure sensor 5, a wind pressure switch 6, and a zirconia oxygen sensor 7 connected with a signal amplifier and a filter.
As shown in figure 1, an air interface, a gas interface and a mixed gas outlet are arranged on a premixer 9, an air inlet 11 is communicated with the air interface, a gas inlet 10 is communicated with the gas interface, the mixed gas outlet is communicated with a combustor 4, a proportional regulating valve 3 is arranged on the gas inlet 10, the proportional regulating valve has a wide regulating range and strong adjustability, can realize different working conditions and different environmental temperatures, has strong environmental change resistance and improved adaptability, is high in regulating speed and quick in response, the air inlet 11 is communicated with a fan 2, a zirconia oxygen sensor 7 connected with a signal amplifier and a filter is arranged on a smoke exhaust pipeline 12, the zirconia oxygen sensor is connected with a signal amplifier and a filter (shown as a signal amplifying and filtering circuit diagram in figure 3) and is electrically connected with a control system, a wind pressure sensor and a wind pressure switch are arranged at the air inlet, the wind pressure sensor 5, the wind pressure switch 6, the proportional regulating valve 3 and the fan 2 are all electrically connected with the control system, the control system 1 comprises an ignition controller, an igniter, a flame detector and a P L C controller 636, wherein the wind pressure sensor 5, the wind pressure switch 6, the wind pressure sensor is connected with the fan 2, the low-temperature-heating sensor is adopted for the purpose of preventing the DC heating sensor from being heated under the DC heating voltage from damaging under the DC heating condition that the DC voltage.
Furthermore, the premixer is a venturi mixer, the air interface is the air inlet of the venturi mixer, the gas interface is the air suction port of the venturi mixer, and the mixed gas outlet is the air outlet of the venturi mixer.
The control system can monitor the instantaneous flow and the accumulated flow of the natural gas in real time, realize input control, effectively judge the real-time combustion state and the tail gas emission, carry out self-adaptive adjustment, and effectively overcome the influence of non-uniform fuel combustion values of various regions on the combustion efficiency.
The use method of the zirconia oxygen sensor in the combustion of natural gas comprises the following steps:
1) the P L C controller gives an ignition starting signal, and the blower works according to the specified rotating speed;
2) the proportional regulating valve is opened after the igniter starts to heat to reach a certain temperature; natural gas enters the premixing cavity at a natural gas inlet to be fully mixed with air;
3) the mixed gas after being fully mixed enters a burner, the mixed gas is ignited under the heating action of an igniter, and the igniter stops heating after ignition and enters a flame detection mode;
4) the P L C controller collects signals of a wind pressure sensor, a wind pressure switch and a zirconia oxygen sensor connected with a signal amplifier and a filter in real time, judges the ignition state according to the collected signals and carries out automatic adjustment, thereby achieving the best working state and higher working efficiency, and timely cutting off the natural gas to ensure the safety and stability of the system when abnormity occurs.
Specifically, according to the comparison between a P L C controller and a set original oxygen content, according to the actual oxygen content deviation, a P L C controller adjusts the opening of a proportional regulating valve to increase or decrease the natural gas amount so that the oxygen content after combustion reaches the original set value, a P L C controller controls and adjusts the duty ratio of a speed regulating signal of a fan to adjust the flame size, meanwhile, a P L C controller controls a zirconia oxygen sensor to detect the oxygen content after combustion in a combustor again, according to the feedback oxygen content value of the oxygen sensor, the P L C controller compares the oxygen content with the originally set oxygen content value again to adjust in a circulating mode until the oxygen content after combustion reaches the original set value.
The state of an air side is effectively judged according to the wind pressure sensor, accidental tempering is prevented, the state of an ignition moment can be effectively detected according to the wind pressure switch, whether tempering and deflagration states exist or not is judged, faults are found, and the fire is immediately stopped, so that the safety and stability of the system are improved; the signal of the oxygen sensor is processed and used, so that the validity and the reliability of the sensor signal are improved, and the stability of control is improved. When the air inlet and outlet holes and the furnace core are seriously blocked, the automatic shutdown is realized according to the feedback of the air pressure sensor and the zirconia oxygen sensor, so that the equipment safety is ensured.
For example, the air side intake is slightly blocked: the air inlet of the air side is slightly blocked, the air pressure of the air inlet side is changed, the air inlet amount is changed, namely the ratio of the premixed air amount to the fuel gas amount is changed, the combustion is insufficient, and the combustion efficiency is reduced; wind pressure data are collected in real time by a wind pressure sensor in the combustion system, combustion tail gas emission parameters are monitored in real time by an oxygen sensor, and when the data change, the quick response is realized, the rotating speed of a fan and the opening degree of a proportional control valve are adjusted, and high-efficiency full combustion is ensured.
The embodiment can realize abundant burning, the combustion efficiency is high, the fuel with the volume can convert the heat energy of utilizing bigger proportion, and can improve zirconia oxygen sensor validity and the reliability in signal transmission process greatly, and then form closed-loop control system, the emission is low, carbon oxide and nitrogen oxide that the burning produced are extremely low, can realize real-time supervision combustion state, the state of the inside flame burning of accurate judgement furnace body, effectual assurance burning is abundant, in time carry out fault recognition, ensure combustion system's safe high-efficient steady operation.
Example 2
The embodiment discloses a signal amplification circuit of a zirconia oxygen sensor, wherein the zirconia oxygen sensor adopts the signal amplification circuit shown in figure 3, the signal amplification circuit comprises a signal amplifier and a filter, the adopted filter is a filter capacitor, external alternating current signal interference is prevented, meanwhile, the amplifier has a common-mode rejection function, signal distortion caused by an external interference source can be effectively prevented, and the reliability and the stability of signals are ensured; the signal amplifier is adopted to amplify the signal, so that the signal can be conveniently acquired and processed by the controller, and the control function can be conveniently realized; however, the signal amplification circuit according to the present invention is not limited to the circuit disclosed in the present embodiment, and may be another signal amplification circuit that achieves the above-described functions.
This embodiment is applied to natural gas combustion system and can realize abundant burning, high combustion efficiency, the fuel with the volume can convert the heat energy of utilizing bigger proportion, and can improve zirconia oxygen sensor validity and reliability in signal transmission process greatly, and then form closed-loop control system, the emission is low, carbon oxide and nitrogen oxide that the burning produced are extremely low, can realize real-time supervision combustion state, the state of the inside flame burning of accurate judgement furnace body, effectual assurance burning is abundant, in time carry out fault identification, ensure combustion system's safe high-efficient steady operation.
Example 3
The embodiment discloses a natural gas flow calculating method based on embodiment 2, which includes the following steps:
1) the P L C controller collects signals of a wind pressure sensor and a zirconia oxygen sensor connected with a signal amplifier and a filter in real time, and the P L C can calculate to obtain the flow of air according to the collected wind pressure data and the sectional area of the air side of the premixer;
2) obtaining an excess air coefficient according to the oxygen content of combustion emission;
3) the P L C controller can calculate the natural gas instantaneous flow according to the air quantity and the excess air coefficient;
4) the accumulated flow can be calculated by integrating the instantaneous flow.
The embodiment can utilize a P L C controller to collect signals, the flow of natural gas is calculated through a zirconia oxygen sensor and an air pressure sensor which are connected with a signal amplifier and a filter, the full combustion of a natural gas system is realized, the combustion efficiency is high, the fuel with the same volume can convert and utilize heat energy with a larger proportion, the effectiveness and the reliability of the zirconia oxygen sensor in the signal transmission process can be greatly improved, the emission is low, carbon oxides and nitrogen oxides generated by combustion are extremely low, the combustion state can be monitored in real time, the combustion state of flame in a furnace body can be accurately judged, the full combustion is effectively ensured, the fault identification is carried out in time, and the safe, efficient and stable operation of the combustion system is ensured.
The specific embodiments are only for explaining the present invention, and not for limiting the present invention, and those skilled in the art can make modifications to the embodiments as required after reading the present specification, but all the embodiments are protected by the patent laws within the scope of the claims of the present invention.
Claims (7)
1. A natural gas combustion closed-loop control system is characterized by comprising a control system, a combustor, a proportion regulating valve, a fan, a wind pressure sensor and a zirconia oxygen sensor;
wherein the burner is respectively communicated with the gas inlet and the air inlet; the proportion regulating valve is arranged at the gas inlet; the air inlet is communicated with the fan; the zirconia oxygen sensor is arranged at the tail part of the combustor or on the smoke exhaust pipeline and is electrically connected with the control system; the wind pressure sensor is arranged at the air inlet; the wind pressure sensor, the proportion regulating valve and the fan are electrically connected with the control system.
2. The natural gas combustion closed-loop control system of claim 1, wherein the zirconia oxygen sensor is connected with a signal amplifier and a filter.
3. The natural gas combustion closed-loop control system of claim 2, further comprising a premixer, wherein the premixer is provided with an air interface, a gas interface and a mixed gas outlet; the air inlet is communicated with the air interface, and the gas inlet is communicated with the gas interface; the mixed gas outlet is communicated with the burner.
4. The natural gas combustion closed-loop control system of claim 3, wherein the control system comprises an ignition controller, an igniter, and a P L C controller.
5. The closed-loop control system for natural gas combustion of claim 4, wherein the premixer is a venturi mixer, the air inlet is an air inlet of the venturi mixer, the gas interface is an air inlet of the venturi mixer, and the mixed gas outlet is an air outlet of the venturi mixer.
6. The closed-loop control system for natural gas combustion of claim 5 further comprising a wind pressure switch.
7. The closed-loop control system for natural gas combustion of claim 6, wherein the heating voltage of the zirconia oxygen sensor is preheated by low-voltage DC5V and then boosted to DC12V for heating.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113757718A (en) * | 2021-09-13 | 2021-12-07 | 营口千千里科技有限公司 | High-efficiency combustion control system and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113757718A (en) * | 2021-09-13 | 2021-12-07 | 营口千千里科技有限公司 | High-efficiency combustion control system and method |
| CN113757718B (en) * | 2021-09-13 | 2024-06-21 | 营口千千里科技有限公司 | High-efficiency combustion control system and method |
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