Heating furnace oxygen-fuel combustion intelligent control system

Abstract

The utility model provides an intelligent control system for total oxygen combustion of a heating furnace. The intelligent control system comprises a fuel gas flow meter, an oxygen flow meter, a discharged flue gas flow meter, a circulating flue gas flow meter, a discharged flue gas regulating valve, an online analysis interlocking control device, a flue gas induced draft fan and a flue gas circulating fan. Smoke at an outlet of the heating furnace is led out through the smoke induced draft fan, one part of smoke is mixed with oxygen, enters an inlet of the smoke circulating fan and enters the heating furnace after being subjected to pressure increasing through the smoke circulating fan, the other part of smoke is divided into oxygen to be subjected to heat exchange with the smoke heat exchanger, heat in the smoke is recycled, and the smoke enters the chimney and then is exhausted into the atmosphere. The automation degree during oxygen-fuel combustion of the heating furnace can be improved, stable operation of operators of the heating furnace is facilitated, long-period operation of oxygen-fuel combustion of the heating furnace is achieved, the heat efficiency of the heating furnace is improved, and therefore energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of petrochemical industry, and particularly relates to an intelligent control system for oxy-fuel combustion of a heating furnace. Background Art

[0002] In recent years, the oxy-fuel combustion technology developed has effectively reduced the emission of NO x and achieved very significant energy conservation and emission reduction effects, and has been more and more widely applied in boilers and melting furnaces.

[0003] In the petrochemical heating furnace industry, the popularization and application of the oxy-fuel combustion technology have encountered many challenges and difficulties. The main problems are that when the heating furnace burns with pure oxygen, the production operation method is significantly different from the combustion method of the heating furnace with air-assisted combustion, the operation difficulty is large, and the negative pressure in the heating furnace hearth is extremely easy to fluctuate, resulting in the flash extinction of the heating furnace. Content of the Utility Model

[0004] The purpose of the utility model is to provide an intelligent control system for oxy-fuel combustion of a heating furnace. The system in the utility model effectively solves the problem of large operation difficulty during oxy-fuel combustion of the heating furnace, can stabilize the combustion condition, and enables the heating furnace to operate in the oxy-fuel combustion condition for a long period.

[0005] The utility model provides an intelligent control system for oxy-fuel combustion of a heating furnace, which includes a heating furnace, an external exhaust gas and oxygen heat exchanger, and a flue gas circulation fan;

[0006] A flue gas outlet is arranged at the top of the heating furnace, and the flue gas outlet is communicated with the inlet of a flue gas induced draft fan. The outlet of the flue gas induced draft fan is divided into two paths. One path is communicated with the flue gas inlet of the external exhaust gas and oxygen heat exchanger through a flue gas external exhaust pipeline, and the other path is communicated with the inlet of the flue gas circulation fan through a flue gas circulation pipeline;

[0007] An external exhaust gas flowmeter, a first flue damper and a first regulating valve are sequentially arranged on the flue gas external exhaust pipeline according to the flue gas flow direction, and the first flue damper and the first regulating valve are arranged in parallel;

[0008] A circulating flue gas flowmeter and a second flue damper are sequentially arranged on the flue gas circulation pipeline according to the flue gas flow direction;

[0009] The oxygen outlet of the external exhaust gas and oxygen heat exchanger is communicated with the inlet of the flue gas circulation fan;

[0010] The outlet of the flue gas circulation fan is communicated with the oxygen inlet at the bottom of the heating furnace.

[0011] Preferably, a third flue damper is arranged at the top of the heating furnace.

[0012] Preferably, a first online oxygen analyzer is provided at the flue gas outlet of the heating furnace.

[0013] Preferably, an oxygen flow meter and a second regulating valve are provided at the oxygen inlet of the external exhaust flue gas and oxygen heat exchanger.

[0014] Preferably, a gas inlet is further provided at the bottom of the heating furnace; the gas inlet is communicated with a gas flow meter and a third regulating valve.

[0015] Preferably, a second online oxygen analyzer is provided at the outlet of the flue gas circulation fan.

[0016] The utility model provides an intelligent control system for oxy-fuel combustion of a heating furnace, which includes a heating furnace, an external exhaust flue gas and oxygen heat exchanger, and a flue gas circulation fan; a flue gas outlet is provided at the top of the heating furnace, and the flue gas outlet is communicated with the inlet of a flue gas induced draft fan. The outlet of the flue gas induced draft fan is divided into two paths. One path is communicated with the flue gas inlet of the oxygen heat exchanger through an external exhaust flue gas pipeline, and the other path is communicated with the inlet of the flue gas circulation fan through a flue gas circulation pipeline; a flue gas induced draft fan, an external exhaust flue gas flow meter, a first flue damper and a first regulating valve are sequentially arranged on the external exhaust flue gas pipeline according to the flue gas flow direction, and the flue damper and the regulating valve are arranged in parallel; a circulating flue gas flow meter and a second flue damper are sequentially arranged on the flue gas circulation pipeline according to the flue gas flow direction; the oxygen outlet of the external exhaust flue gas and oxygen heat exchanger is communicated with the inlet of the flue gas circulation fan; the outlet of the flue gas circulation fan is communicated with the oxygen inlet at the bottom of the heating furnace. By adding a flue gas circulation fan in the utility model, oxygen is incorporated into the fan inlet, and the operation of the fan mixes oxygen and flue gas, replacing the flue gas and oxygen mixer, so that the mixing effect of flue gas and oxygen is not affected by the device load; by adding an external exhaust flue gas flow meter and a circulating flue gas flow meter to measure instantaneous data, oxygen and flue gas are proportioned according to the data, which is convenient for operators to operate; a flue gas induced draft fan and a flue gas circulation fan are provided, and through the control of the two fans, the influence on the furnace negative pressure during the adjustment of the circulating flue gas volume is reduced, and stable operation can be achieved; an external exhaust flue gas by-pass line is added, and a regulating valve is provided on the by-pass line to accurately control the amount of flue gas sent out through the regulating valve. Through the above improvements, the utility model can improve the automation degree during the oxy-fuel combustion of the heating furnace, facilitate the stable operation of the heating furnace operator, realize the long-term operation of the oxy-fuel combustion of the heating furnace, improve the thermal efficiency of the heating furnace, and thus achieve energy conservation and emission reduction. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0018] Figure 1 This is a schematic structural diagram of the intelligent control system for the all-oxygen combustion of the heating furnace in the present utility model;

[0019] Among them, 1 is the heating furnace, 2 is the third flue damper, 3 is the first on-line oxygen analyzer, 4 is the flue gas induced draft fan, 5 is the external exhaust flue gas flowmeter, 6 is the first flue damper, 7 is the first regulating valve, 8 is the oxygen flowmeter, 9 is the second regulating valve, 10 is the external exhaust flue gas and oxygen heat exchanger, 11 is the circulating flue gas flowmeter, 12 is the second flue damper, 13 is the flue gas circulation fan, 14 is the second on-line oxygen analyzer, 15 is the gas flowmeter, 16 is the third regulating valve, and 17 is the chimney. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0021] The present utility model provides an intelligent control system for the all-oxygen combustion of a heating furnace, including a heating furnace, an external exhaust flue gas and oxygen heat exchanger, and a flue gas circulation fan;

[0022] A flue gas outlet is provided at the top of the heating furnace, and the flue gas outlet is connected to the inlet of the flue gas induced draft fan. The outlet of the flue gas induced draft fan is divided into two paths. One path is connected to the flue gas inlet of the oxygen heat exchanger through the external exhaust flue gas pipeline, and the other path is connected to the inlet of the flue gas circulation fan through the flue gas circulation pipeline;

[0023] The external exhaust flue gas pipeline is sequentially provided with a flue gas induced draft fan, an external exhaust flue gas flowmeter, a first flue damper, and a first regulating valve in the flue gas flow direction. The flue damper and the regulating valve are arranged in parallel;

[0024] The flue gas circulation pipeline is sequentially provided with a circulating flue gas flowmeter and a second flue damper in the flue gas flow direction;

[0025] The oxygen outlet of the external exhaust flue gas and oxygen heat exchanger is connected to the inlet of the flue gas circulation fan;

[0026] The outlet of the flue gas circulation fan is connected to the oxygen inlet at the bottom of the heating furnace.

[0027] In an embodiment of the present utility model, the structure of the intelligent control system for the all-oxygen combustion of the heating furnace is as Figure 1As shown in the figure. The high-temperature flue gas in the convection section discharged from the heating furnace 1 is led out by the flue gas induced draft fan 4, and then divided into two paths. One path enters the external exhaust flue gas flowmeter 5, the first flue gas baffle 6, and the flue gas-oxygen heat exchanger 10 to exchange heat with the combustion-supporting oxygen from outside the device. The cooled flue gas after heat exchange enters the chimney 17 and is discharged. The other path passes through the circulating flue gas flowmeter 11, mixes with the oxygen after heat exchange, is pressurized by the flue gas circulating fan 13, and then enters the heating furnace 1 as the combustion-supporting medium for the fuel.

[0028] The intelligent all-oxygen combustion control system of the heating furnace includes the heating furnace 1, the third flue gas baffle 2, the first oxygen on-line analyzer 3, the flue gas induced draft fan 4, the external exhaust flue gas flowmeter 5, the first flue gas baffle 6, the first regulating valve 7, the oxygen flowmeter 8, the second regulating valve 9, the external exhaust flue gas and oxygen heat exchanger 10, the circulating flue gas flowmeter 11, the second flue gas baffle 12, the flue gas circulating fan 13, the second oxygen on-line analyzer 14, the gas flowmeter 15, the third regulating valve 16, and the chimney 17.

[0029] In an embodiment of the present invention, a third flue gas baffle 2 is provided at the top of the heating furnace 1 to control the discharge of flue gas from the flue gas outlet.

[0030] In an embodiment of the present invention, a first oxygen on-line analyzer 3 is provided at the flue gas outlet to monitor and detect the oxygen content in the gas. The flue gas outlet is connected to the flue gas induced draft fan 4. The flue gas induced draft fan 4 is used to draw out the high-temperature flue gas in the heating furnace 1. The outlet of the flue gas induced draft fan 4 is divided into two paths. One path is connected to the flue gas inlet of the external exhaust flue gas and oxygen heat exchanger 10 through the flue gas external exhaust pipeline, so that a part of the high-temperature flue gas exchanges heat with oxygen in the external exhaust flue gas and oxygen heat exchanger 10 and is discharged to the atmosphere through the chimney 17. The other path is connected to the inlet of the flue gas circulating fan 13 through the flue gas circulating pipeline; so that the remaining part of the flue gas passes through the circulating flue gas fan 13 and is circulated into the heating furnace 1.

[0031] In an embodiment of the present invention, an external exhaust flue gas flowmeter 5, a first flue gas baffle 6, and a first regulating valve 7 are sequentially arranged on the flue gas external exhaust pipeline in the direction of flue gas flow. The first flue gas baffle 6 and the first regulating valve 7 are arranged in parallel. The external exhaust flue gas flowmeter 5 is used to measure the instantaneous flow rate of the external exhaust flue gas, and the instantaneous flow rate of the external exhaust flue gas is adjusted by the opening degrees of the first flue gas baffle 6 and the first regulating valve 7. After the first flue gas baffle 6 is adjusted to an appropriate opening degree, the first regulating valve 7 is used to accurately adjust the external exhaust amount of the flue gas, so as to control the negative pressure in the heating furnace stably and ensure the combustion condition of the heating furnace.

[0032] In one embodiment of the utility model, the exhaust flue gas and oxygen heat exchanger 10 is used to provide a place for heat exchange between high-temperature flue gas and oxygen. The exhaust flue gas and oxygen heat exchanger 10 is provided with an oxygen inlet, an oxygen outlet, a flue gas inlet and a flue gas outlet. An oxygen flowmeter 8 and a second regulating valve 9 are provided at the oxygen inlet. The oxygen flowmeter 8 is used to measure the instantaneous flow of oxygen entering the exhaust flue gas and oxygen heat exchanger 10, and the instantaneous flow of oxygen is adjusted by the opening of the second regulating valve 9; the flue gas outlet is connected to the chimney 17 for discharging the flue gas after heat exchange; the oxygen outlet is connected to the flue gas circulation fan 13 for transporting the oxygen after heat exchange to the heating furnace as a combustion-supporting medium for the fuel gas.

[0033] In one embodiment of the utility model, the flue gas circulation pipeline is provided with a circulating flue gas flow meter 11 and a second flue baffle 12 in sequence according to the flue gas flow direction; the circulating flue gas flow meter 11 is used to measure the instantaneous flow of the circulating flue gas, and according to the flow display, the flow of oxygen is adjusted through the second regulating valve 9, and the flow of fuel gas is adjusted through the third regulating valve 16, so as to achieve the purpose of stabilizing the oxygen-fuel ratio and the oxygen content in the circulating flue gas.

[0034] In one embodiment of the utility model, the flue gas from the flue gas induced draft fan 4 entering the inlet of the flue gas circulation fan 13 and the oxygen after heat exchange through the exhaust smoke and oxygen heat exchanger 10 are mixed through the flue gas circulation fan 13 to replace the traditional oxygen and flue gas mixer, and the outlet is connected to the burner of the heating furnace 1.

[0035] In one embodiment of the utility model, a second oxygen online analyzer 14 is provided at the outlet of the flue gas circulation fan 13, and its function is to detect the oxygen content in the combustion-supporting gas after oxygen addition to ensure that the oxygen content in the combustion-supporting gas is uniform. The second oxygen online analyzer 14 and the first oxygen online analyzer 3 constitute an online analysis interlocking control system. The deviation of the analysis data of the two oxygen online analyzers indicates the degree of oxygen mixing uniformity. At the same time, a cascade control is set with the second regulating valve 9 to control the oxygen content after mixing to ≯35%.

[0036] The prior art has only one flue gas exhaust fan. When adjusting the flue gas circulation volume, it has a great impact on the furnace pressure of the heating furnace, causing combustion fluctuations. The utility model adopts a dual fan setting of a flue gas exhaust fan 4 and a flue gas circulation fan 13. When the heating furnace load needs to be adjusted, the amount of circulating flue gas entering the heating furnace is adjusted by adjusting the frequency of the flue gas circulation fan 13. The furnace negative pressure is stably controlled by the dual fans to avoid huge fluctuations that cause the burner to flash.

[0037] In an embodiment of the present utility model, a gas inlet is further provided at the bottom of the heating furnace 1; the gas inlet is communicated with a gas flowmeter 15 and a third regulating valve 16. The fuel gas flowmeter 15 is used to measure the instantaneous amount of fuel gas entering the heating furnace, and the instantaneous flow rate of the fuel gas is adjusted by the opening degree of the third regulating valve 16.

[0038] In an embodiment of the present utility model, the oxygen-fuel ratio is set according to the instantaneous values measured by the fuel gas flowmeter 15 and the oxygen flowmeter 8, fuel gas: oxygen = 2.05:1, and is controlled by the third regulating valve 16 and the second regulating valve 9 to ensure the ratio of fuel gas and oxygen entering the heating furnace and stable combustion.

[0039] Compared with the prior art, the present utility model has the following advantages:

[0040] When the oxygen and flue gas mixer adopted in the prior art operates at a low load of the device, due to low pressure and slow gas flow rate, the phenomenon of uneven mixing frequently occurs. The present utility model replaces the oxygen and flue gas mixer with a flue gas circulation fan. Oxygen is incorporated into the fan inlet, and the operation of the fan mixes oxygen and flue gas, replacing the flue gas and oxygen mixer, so that the mixing effect of flue gas and oxygen is not affected by the device compliance.

[0041] In the prior art, there is no flow detection for the externally discharged flue gas and the circulating flue gas. Operators can only adjust the ratio of oxygen and flue gas through the furnace negative pressure and the on-line oxygen analyzer, resulting in adjustment lag, frequent operation by on-site personnel, and great operation difficulty. The present utility model measures the instantaneous data by adding an externally discharged flue gas flowmeter and a circulating flue gas flowmeter, and proportions oxygen and flue gas according to the data, which is convenient for operators to operate.

[0042] In the prior art, there is only one flue gas extraction fan. When adjusting the flue gas circulation volume, it has a great impact on the furnace pressure of the heating furnace, resulting in combustion fluctuations. The present utility model is provided with a flue gas extraction fan and a flue gas circulation fan. Through the control of the double fans, the impact on the furnace negative pressure during the adjustment of the circulating flue gas volume is reduced, and stable operation can be achieved.

[0043] In the prior art, the amount of externally discharged flue gas is controlled by the opening degree of the first flue damper 6. Due to the valve type of the flue gas damper, the externally discharged flue gas volume cannot be accurately regulated, resulting in violent fluctuations in the furnace pressure of the heating furnace. The furnace fire of the heating furnace is extinguished due to the fluctuation of the furnace negative pressure. An externally discharged flue gas by-pass line is added, and a first regulating valve 7 is provided on the by-pass line to accurately regulate the externally delivered flue gas volume.

Claims

1. An intelligent control system for full oxygen combustion in a heating furnace, characterized in that: It includes a heating furnace, an exhaust gas and oxygen heat exchanger and a flue gas circulation fan; A smoke outlet is provided on the top of the heating furnace, and the smoke outlet is connected to the inlet of the smoke exhaust fan. The outlet of the smoke exhaust fan is divided into two paths, one of which is connected to the smoke inlet of the exhaust smoke and oxygen heat exchanger through a smoke exhaust pipeline, and the other is connected to the inlet of the smoke circulation fan through a smoke circulation pipeline; The smoke exhaust pipeline is provided with an exhaust smoke flow meter, a first smoke duct baffle and a first regulating valve in sequence according to the smoke flow direction, and the first smoke duct baffle and the first regulating valve are arranged in parallel; The flue gas circulation pipeline is provided with a circulating flue gas flow meter and a second flue baffle in sequence according to the flue gas flow direction; The oxygen outlet of the exhaust flue gas and oxygen heat exchanger is connected to the inlet of the flue gas circulation fan; The outlet of the flue gas circulation fan is connected to the oxygen inlet at the bottom of the heating furnace.

2. The intelligent control system for full oxygen combustion of a heating furnace according to claim 1 is characterized in that: A third flue baffle is arranged on the top of the heating furnace.

3. The intelligent control system for full oxygen combustion of a heating furnace according to claim 1 is characterized in that: A first oxygen online analyzer is arranged at the flue gas outlet of the heating furnace.

4. The intelligent control system for full oxygen combustion of a heating furnace according to claim 1 is characterized in that: The oxygen inlet of the exhaust flue gas and oxygen heat exchanger is provided with an oxygen flow meter and a second regulating valve.

5. The intelligent control system for full oxygen combustion of a heating furnace according to claim 1 is characterized in that: A gas inlet is also provided at the bottom of the heating furnace; the gas inlet is connected to a gas flow meter and a third regulating valve.

6. The intelligent control system for full oxygen combustion of a heating furnace according to claim 1 is characterized in that: A second oxygen online analyzer is arranged at the outlet of the flue gas circulation fan.

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