Heating Furnace Energy Saving Control System

Abstract

The present invention discloses an energy-saving control system for a heating furnace, which includes a DCS control system, a mainframe, an operation station, an engineer station, a flue gas analyzer, a flue gas CO analysis sensor, a flue gas O2 analysis sensor, a temperature sensor, a pressure sensor, an actuator, an optical fiber temperature measurement system and a temperature measurement optical fiber; the mainframe is connected to the upper-level DCS control system; the operation station and the engineer station are respectively connected to the mainframe; the flue gas analyzer and the optical fiber temperature measurement system are respectively connected to the mainframe; the flue gas CO analysis sensor and the flue gas O2 analysis sensor are respectively connected to the flue gas analyzer; the temperature measurement optical fiber is connected to the optical fiber temperature measurement system; the actuator is connected to the mainframe. The present invention can automatically establish an independent control model for the heating furnace, enabling the heating furnace to reach the best and most energy-saving combustion operation state.

Description

Technical Field

[0001] The present invention relates to a heating furnace device burning gaseous fuel, and particularly to an energy-saving control system for a heating furnace. Background Art

[0002] In modern industrial production, taking petrochemical production as an example, petrochemical production plays an extremely important role. It is the provider of most of the energy and raw materials for modern industry, the lubricant and broad-spectrum energy for the normal operation of modern society, and also a large energy consumer in modern industry. Petrochemical enterprises have thousands of heating furnaces burning gaseous fuel, which provide heat energy for the normal operation of process units. These heating furnaces account for most of the total production energy consumption of petrochemical enterprises. If each heating furnace can operate safely, burn completely, and be in the best heating process, then it will be in the best energy-saving working state. The country requires industrial upgrading and major enterprises to save energy and reduce emissions. If all heating furnaces using fuel gas in petrochemical enterprises can be in the best combustion working state with the highest energy efficiency, the energy saved nationwide every year will be extremely huge, and the energy-saving benefits will also be very remarkable.

[0003] Figure 2 It is a control flow chart of a conventional heating furnace and a waste heat recovery system. The heating furnace uses gaseous fuel gas to enter the furnace chamber of the heating furnace for combustion, generating heat to heat the chemical raw materials in the furnace tubes of the heating furnace to reach the temperature required by the process. The heating furnace controls the flow rates of air and fuel gas entering the furnace chamber of the heating furnace, and controls the negative pressure in the furnace chamber of the heating furnace to achieve safe and complete combustion of the fuel gas. The flue gas after combustion carries a huge amount of heat, and the waste heat of the flue gas of the heating furnace needs to be recovered to achieve an energy-saving effect. This is the waste heat recovery system of the heating furnace, which exchanges heat between the flue gas containing a huge amount of heat and the air required by the heating furnace, so that the temperature of the air entering the heating furnace rises, thereby reducing the consumption of fuel gas.

[0004] Figure 3It is the control flow chart of the vacuum furnace in the atmospheric and vacuum distillation unit during the petrochemical production process. This control flow chart is a relatively common control scheme for the heating furnace in the petrochemical production process. To avoid coking of the furnace tubes in the heating furnace, which may cause accidents such as furnace tube rupture. A large number of thermocouples on the surface of the furnace tubes are installed on the furnace tube walls to detect the temperature change inside the furnace tubes in real time, and to detect whether the medium flow rate inside the furnace tubes slows down and the medium temperature rises too high due to coking of the furnace tubes, resulting in accidents such as furnace tube rupture. The thermocouples on the surface of the furnace tubes require an insertion depth of several meters. Each thermocouple needs to be connected from the heating furnace site to the device cabinet room through compensating wires, and is connected to the device DCS control system through a safety barrier (intrinsic safety control system) for data recording and processing, with a huge overall investment. In addition, the furnace tubes are located inside the heating furnace furnace. Generally, the furnace temperature is much higher than the medium temperature inside the furnace tubes. This poses strict requirements for the manufacture and installation of the thermocouples on the surface of the furnace tubes. The installation of the thermocouples on the surface of the furnace tubes must isolate heat from the furnace. Once the heat isolation is not good, the temperature detected by the surface thermocouple is no longer the temperature of the furnace tube wall, but the furnace temperature. If it is necessary to repair the surface thermocouple, the furnace must be shut down for maintenance. Now, petrochemical plants generally operate continuously for four years before they can be shut down for maintenance.

[0005] For the control of a conventional heating furnace, generally, the flue gas damper is controlled by the pressure in the convection section of the furnace to control the convection section pressure at -20 Pa (negative pressure), and it is generally a fixed-value control under normal circumstances. In addition, an oxygen zirconia O2 analyzer is installed in the heating furnace to detect the content of O2 in the flue gas of the heating furnace. The purpose is to detect the combustion condition of the heating furnace and try to achieve complete combustion of the fuel in the heating furnace to save energy. Generally, the content of O2 in the flue gas of the heating furnace is used to control the opening of the air damper of the heating furnace. By controlling the total amount of combustion air, the remaining O2 content in the flue gas is minimized.

[0006] The oxygen zirconia O2 measurement uses the point-contact O2 measurement principle. During the use of the zirconia head of the oxygen zirconia, since it needs to contact the flue gas, it is prone to failure during long-term operation. Therefore, in the actual control of the heating furnace, the data of the O2 content in the flue gas measured by the oxygen zirconia O2 analyzer generally cannot be used as a control parameter to participate in the control of the opening of the air damper of the heating furnace. The current common practice is to manually adjust the air damper once using the work experience of the operator. However, generally, a heating furnace is composed of multiple burners. Generally, there is only one main air duct. In this way, there will be a slight difference in the air pressure entering different burners, and the same is true for the fuel gas channels. Thus, manually adjusting the opening of the air damper of the heating furnace burners cannot achieve precise control of the burners. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an energy-saving control system for a heating furnace, so that each heating furnace is always in the best and most energy-saving combustion operation state, so as to achieve an energy-saving and emission-reduction working mode and meet the increasingly stringent national energy-saving and emission-reduction enterprise production standards.

[0008] To solve the above technical problems, the technical solution of the present invention is as follows:

[0009] An energy-saving control system for a heating furnace, including a DCS control system, a host computer, an operation station, an engineer station, a flue gas analyzer, a flue gas CO analysis sensor, a flue gas O2 analysis sensor, a temperature sensor, a pressure sensor, an actuator, an optical fiber temperature measurement system and a temperature measurement optical fiber; the host computer is connected to the upper DCS control system; the operation station and the engineer station are respectively connected to the host computer; the flue gas analyzer and the optical fiber temperature measurement system are respectively connected to the host computer; the flue gas CO analysis sensor and the flue gas O2 analysis sensor are respectively connected to the flue gas analyzer; the temperature measurement optical fiber is connected to the optical fiber temperature measurement system; the actuator is connected to the host computer.

[0010] Preferably, in the inlet and outlet furnace tubes of the heating furnace, optical fiber protection sleeves are pre-buried; the temperature measurement optical fiber is inserted into the optical fiber protection sleeve.

[0011] Preferably, within the optical fiber length of the temperature measurement optical fiber, non-stop temperature measurement is carried out every 25 cm.

[0012] Preferably, the optical fiber temperature measurement system measures various temperature data inside the furnace tube through the temperature measurement optical fiber and transmits them to the host computer, and the host computer generates a furnace tube temperature rise curve and a furnace tube length temperature difference curve.

[0013] Preferably, the actuator includes a chimney regulating baffle and a furnace bottom pneumatic damper; the pressure sensor detects the pressure in the convection chamber of the heating furnace furnace, and the host computer controls the chimney regulating baffle according to the pressure in the convection chamber of the furnace; the flue gas O2 analysis sensor detects the O2 content in the flue gas of the heating furnace chimney, and the host computer controls the opening degree of the furnace bottom pneumatic damper according to the O2 content in the flue gas.

[0014] Preferably, the host computer controls the actuator according to the detected temperature, pressure, flue gas O2 content, flue gas CO content, furnace tube temperature rise curve and the fuel gas flow rate of the heating furnace, and establishes an optimal combustion temperature rise model for the heating furnace.

[0015] Preferably, the actuator includes an induced draft fan and a blower; the host computer controls the frequency conversion of the induced draft fan according to the pressure in the convection chamber of the furnace and controls the frequency conversion of the blower according to the O2 content in the flue gas of the chimney.

[0016] Preferably, the host computer monitors the real-time temperature and temperature difference of the medium in the furnace tubes entering and leaving the heating furnace. When the temperature difference curve of the furnace tube length changes, it automatically calculates the coking thickness of the furnace tube. When the coking thickness of the furnace tube exceeds the alarm value required by the process, the host computer sends an alarm signal to the DCS control system.

[0017] Preferably, the actuator participates in the interlock setting; the signal input / output cards participating in the interlock are redundantly designed, and the controller is also redundantly designed.

[0018] Preferably, an automatic ignition device and a pilot flame monitoring device are installed on the heating furnace burner; the host computer automatically ignites the pilot lamp through the automatic ignition device and monitors the pilot flame information through the pilot flame monitoring device.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The present invention adopts advanced software and hardware control technologies and is independent of the DCS control system of the process device. An independent control model can be automatically established for each heating furnace, including a detection system for the furnace tube temperature rise curve and the furnace tube length temperature difference curve, real-time O2 and CO analysis of the flue gas, and automatically adjusts and controls the operating state of the heating furnace, so that the heating furnace is always in the best and most energy-saving combustion operating state, in order to achieve the energy-saving and emission-reduction working mode and meet the increasingly stringent national energy-saving and emission-reduction enterprise production standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural diagram of the energy-saving control system of the heating furnace of the present invention;

[0022] Figure 2 is a control flow chart of a conventional heating furnace and a waste heat recovery system;

[0023] Figure 3 is a control flow chart of a vacuum furnace in a crude oil distillation unit;

[0024] Figure 4 is a schematic diagram of the installation of the optical fiber temperature measurement system of the heating furnace of the present invention;

[0025] Figure 5 is a schematic structural diagram of the newly added laser O2 and CO analyzers of the heating furnace of the present invention;

[0026] Figure 6 is a control flow chart of the DCS control system of the heating furnace of the present invention, with an output signal of the fuel gas flow rate of the heating furnace added to the energy-saving control system of the heating furnace.

[0027] Figure 1In the figure: 1 - DCS control system; 2 - Host computer communication card; 3 - Host; 4 - Operator station; 5 - Engineer station; 6 - First communication card; 7 - Flue gas analyzer; 8 - Flue gas CO analysis sensor; 9 - Flue gas O2 analysis sensor; 10 - Temperature signal input card; 11 - Temperature sensor; 12 - Pressure signal input card; 13 - Pressure sensor; 14 - First control signal output card; 15 - First actuator; 16 - Second control signal output card; 17 - Second actuator; 18 - Second communication card; 19 - Optical fiber temperature measurement system; 20 - Temperature measurement optical fiber

[0028] Figure 2 In the figure: P1 - 4 is the bottom pressure of the furnace; P5 - 6 is the top pressure of the furnace; P7 - 8 is the pressure of the flue gas leaving the convection section; PA1 is the pressure of the air entering the preheater; PA2 is the pressure of the air leaving the preheater; PG1 is the pressure of the flue gas entering the preheater; PG2 is the pressure of the flue gas leaving the preheater; T1~4 is the flue gas temperature in the radiant section; T5~6 is the temperature of the flue gas leaving the radiant section; T7~8 is the temperature of the flue gas leaving the convection section; T9 is the temperature of the flue gas discharged from the chimney; TA1 is the temperature of the air entering the preheater; TA2 is the temperature of the air leaving the preheater; TG1 is the temperature of the flue gas entering the preheater; TG2 is the temperature of the flue gas leaving the preheater; A1 is the zirconia O2 analyzer; DP1 - 2 is the chimney regulating baffle; DP3 is the flue duct bypass seal baffle; DP4 is the flue duct seal baffle; DA1~2 are the pneumatic butterfly valves in the hot air duct; AD1~6 are the pneumatic dampers in the air duct; DA3 is the air bypass baffle; DA4~5 are the baffle actuators of the induced draft and forced draft fans

[0029] Figure 3 In the figure: TI - 108SA~H (SKIN), 109SA~H (SKIN), 110SA~H (SKIN), 111SA~H (SKIN) represent the thermocouples on the surface of the heating furnace tubes

[0030] Figure 4 In the figure: 21 - Vacuum heating furnace; 22 - Discharge furnace tube; 23 - Temperature measurement optical fiber; 24 - Shut-off gate valve; 25 - Optical fiber self-sealing device; 26 - Optical fiber connection nozzle; 27 - Feed furnace tube; 28 - Optical fiber protection sleeve

[0031] Figure 5 In the figure: Chimney regulating baffle actuator Pressure behind the regulating baffle Pressure in front of the regulating baffle Is the laser O2 analyzer (newly added); Laser CO analyzer (newly added); Temperature of the flue gas leaving the convection section Flue gas analyzer (original zirconia O2 analyzer, cancelled); Temperature of the flue gas entering the convection section Flue gas inlet convection pressure; Industrial television; Radiant furnace temperature; Radiant coil tube wall temperature; Furnace bottom pressure; Furnace bottom pneumatic damper; Air inlet branch duct pressure; Air inlet branch duct temperature; Duct pneumatic regulating butterfly valve. Specific implementation manner

[0032] The following further describes the specific implementation manner of the present invention in conjunction with the accompanying drawings. It should be noted here that the description of these implementation manners is used to help understand the present invention, but does not constitute a limitation on the present invention. In addition, the technical features involved in the various implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] As Figure 1 shown, a heating furnace energy-saving control system includes a DCS control system 1, a host 3, an operation station 4, an engineer station 5, a flue gas analyzer 7, a flue gas CO analysis sensor 8, a flue gas O2 analysis sensor 9, a temperature sensor 11, a pressure sensor 13, an actuator, an optical fiber temperature measurement system 19, and a temperature measurement optical fiber 20; the host 3 is connected to the upper DCS control system 1; the operation station 4 and the engineer station 5 are respectively connected to the host 3; the flue gas analyzer 7 and the optical fiber temperature measurement system 19 are respectively connected to the host 3; the flue gas CO analysis sensor 8 and the flue gas O2 analysis sensor 9 are respectively connected to the flue gas analyzer 7; the temperature measurement optical fiber 20 is connected to the optical fiber temperature measurement system 19; the actuator is connected to the host 3.

[0034] In this embodiment, the actuator includes a first actuator 15 and a second actuator 17, and may also include several different types of actuators, and there is no limitation on the number of actuators. Among them, the host 3 is connected to the DCS control system 1 through an upper computer communication card 2; the host 3 is connected to the flue gas analyzer 7 through a first communication card 6; the host 3 is connected to the temperature sensor 11 through a temperature signal input card 10; the host 3 is connected to the pressure sensor 13 through a pressure signal input card 12; the host 3 is connected to the first actuator structure 15 through a first control signal output card 14; the host 3 is connected to the second actuator 17 through a second control signal output card 16; the host 3 is connected to the optical fiber temperature measurement system 19 through a second communication card 18. In order to meet the requirements of the long-term safe operation of the energy-saving control system, all hardware is subjected to aging treatment.

[0035] In one embodiment, the present invention includes a heating furnace furnace tube heating curve detection function module. As Figure 4As shown in the figure, in the pressure-reducing heating furnace 21 of this embodiment, laser fiber temperature measurement is adopted. In the inlet and outlet furnace tubes of the heating furnace, fiber optic protection sleeves 28 are pre-buried. Since the diameter of the temperature-measuring optical fiber is very small, only φ3mm, therefore, its protection sleeve can also be made very thin, and the volume occupied in the furnace tube can be ignored. The wall thickness of the protection sleeve is determined according to the pressure rating of the furnace tube. Generally, a DN10 sleeve is sufficient, and a sleeve with a thicker wall can be selected. In order to prevent the possibility of accidents caused by the rupture of the sleeve due to sleeve quality problems, high-temperature and high-pressure media entering the sleeve and squeezing the temperature-measuring optical fiber to leak, the temperature-measuring optical fiber is installed using an optical fiber self-sealing device 25. The optical fiber temperature measurement system adopts a flanged installation method. The furnace tube corresponding to the optical fiber connection nozzle 26 uses a DN25 sleeve to facilitate the installation of the optical fiber self-sealing device 25. A cut-off gate valve 24 is also provided above the optical fiber connection nozzle 26.

[0036] In this embodiment, the temperature-measuring optical fiber 23 in the optical fiber temperature measurement system can perform non-interval temperature measurement at intervals of 25 cm within the optical fiber length. In this way, both the inlet furnace tube 27 and the outlet furnace tube 22 can perform non-interval temperature measurement. When the heating furnace starts up, the energy-saving control system measures the temperature rise of the inlet and outlet furnace tubes of the heating furnace, and finally forms two temperature-rise curves. One temperature-rise curve is the furnace tube temperature-rise curve, including the dimensions of temperature and time, and the other is the furnace tube length temperature difference curve, including the two dimensions of temperature and furnace tube length. The furnace tube temperature-rise curve is used for the automatic model establishment of the heating furnace, and the furnace tube length temperature difference curve is used for the calculation, alarm and interlock of the coking thickness of the heating furnace tubes.

[0037] In this embodiment, the optical fiber temperature measurement system 19 is installed in the cabinet room, in a non-explosion-proof area, and is connected to the second communication card 18 through the serial port RS-232. The optical fiber temperature measurement system 19 transmits the temperature data of each point in the furnace tube measured by the temperature-measuring optical fiber 20 to the host computer 3, and the host computer 3 automatically generates two temperature measurement curves.

[0038] In one embodiment, the present invention includes a function module for controlling the negative pressure in the heating furnace furnace chamber.

[0039] As Figure 5 shown in the figure, a laser O2 analyzer is used to measure the content of residual O2 in the flue gas. The laser measurement uses a linear, non-contact O2 measurement principle, and a laser O2 measuring instrument is installed on the diameter of the heating furnace chimney. Since the laser O2 analyzer uses non-contact measurement, the laser O2 measuring instrument has high accuracy, high reliability and high repeatability. This O2 content data will be used to adjust the pneumatic damper at the bottom of the heating furnace. At the same time, a laser CO analyzer is used to measure the CO content in the flue gas to control the CO content in the flue gas to zero, achieving complete combustion of the heating furnace.

[0040] In this embodiment, the flue gas baffle is controlled according to the convection chamber pressure (negative pressure), and the bottom damper of the heating furnace is controlled according to the O2 content in the flue gas.

[0041] In one embodiment, the present invention includes an automatic model establishment function module for a heating furnace.

[0042] In this embodiment, during the design and operation of the heating furnace, the influence of altitude, climatic atmospheric pressure, season, morning and evening, and earth latitude on the negative pressure of the heating furnace furnace chamber is generally not considered. Therefore, the energy-saving control system of this designed heating furnace automatically establishes a control model for the heating furnace by software based on the temperature, pressure, flue gas O2 content, flue gas CO content, heating furnace tube temperature rise curve information, and heating furnace fuel gas flow installed on the heating furnace body. The combustion temperature rise models of different heating furnaces are different, and their optimal combustion point negative pressures are also different. This energy-saving control system of the heating furnace can automatically find the optimal combustion parameters of the heating furnace for the control of the heating furnace at the optimal negative pressure, making the heating furnace fully in the optimal combustion state and achieving the maximum energy-saving and emission-reduction effect of the heating furnace.

[0043] In one embodiment, the present invention includes a waste heat recovery control function module.

[0044] In this embodiment, the energy-saving control system of the heating furnace fully considers the heat exchange efficiency of the flue gas / air preheater and controls the frequency conversion of the induced draft fan according to the pressure (negative pressure) of the furnace convection chamber, and controls the frequency conversion of the forced draft fan according to the O2 content provided by the chimney flue gas laser O2 content analyzer. Only by making full use of the large amount of residual heat in the flue gas of the heating furnace can energy be saved.

[0045] In one embodiment, the present invention includes a heating furnace tube coking detection function module.

[0046] In this embodiment, the energy-saving control system of the heating furnace uses an optical fiber temperature measurement system to monitor the real-time temperature and temperature difference of the medium inside the furnace tubes entering and leaving the heating furnace, and at the same time compares the heating furnace temperature rise curve and the temperature difference curve. When the temperature difference curve changes, the system provides coking data of the furnace tubes through software, including the furnace tube number and the coking thickness of the furnace tubes. When the coking thickness of the furnace tubes exceeds the alarm value required by the process, the host can provide an alarm signal to the device DCS control system.

[0047] In one embodiment, the present invention includes a heating furnace and waste heat recovery safety management function module.

[0048] The heating furnace heats the medium inside the furnace tubes by burning fuel gas to achieve the temperature rise process of the medium required by the process. During this process, there are many high-temperature, high-pressure, flammable and explosive gases, and various parameters change greatly and the process is complex. All these are likely to cause potential safety hazards and the possibility of equipment damage, fire and explosion. Therefore, the safety management of the heating furnace and waste heat recovery is very important. In this embodiment, a SIL assessment level 1 design is adopted. The signal input cards participating in the interlock are redundantly designed, the controller is also redundantly designed, and the interlock signal output cards are also redundantly designed. The flue damper, air damper, blower, induced draft fan, etc. all participate in the interlock, which is realized by the host through software.

[0049] In one embodiment, the present invention includes a heating furnace ignition and flame monitoring function module.

[0050] The heating furnace heats the medium inside the furnace tubes in the furnace chamber by burning fuel gas to achieve its heating function. In order to ensure safe combustion, a pilot light is set in the heating furnace. Before the heating furnace starts operation, the pilot light must be lit first, and then the main fuel line can be opened. Therefore, the ignition and flame detection of the pilot light are extremely important from a safety perspective.

[0051] In this embodiment, an automatic ignition device and a pilot light flame monitoring device are installed on the burner. The pilot light can be automatically ignited through the system soft switch in the control room, and the pilot light flame information can be displayed on the pilot light flame monitoring system. Moreover, the fuel gas of this burner can be evenly distributed, enabling complete combustion of the fuel, so that the flame is stable, no nitrogen oxides are generated, and the best energy conservation and emission reduction effect is achieved.

[0052] As Figure 6 shown, the control flow chart of the DCS control system in the vacuum feed heating furnace. In the figure, the fuel gas flow rate is distributed by a safety barrier or a signal distributor in the cabinet room to allocate a signal to the heating furnace energy-saving control system.

[0053] Taking the common 3 million tons / year atmospheric and vacuum distillation unit in the modern petrochemical industry as an example, during the normal operation of the unit, the atmospheric heating furnace requires 2400 m 3 / h of fuel gas, and the vacuum heating furnace requires 2400 m 3 / h of fuel gas. In this way, when the unit operates normally for 1 year, the total amount of fuel gas required is as high as 42,048,000 m 3 . Calculated at an average fuel gas price of 3 yuan / m 3 , only the atmospheric and vacuum heating furnaces of a single 3 million tons / year atmospheric and vacuum distillation unit will burn more than 126 million yuan worth of fuel gas every year; taking the common 2.6 million tons / year continuous reforming unit in the modern petrochemical industry as an example, during the normal operation of the unit, the reforming four-in-one heating furnace 201 requires 3400 m 3 / h of fuel gas; 202 furnace requires 4700 m 3Fuel gas of / h; Furnace 203 requires 4400 m 3 / h of fuel gas; Furnace 204 requires 3500 m 3 / h of fuel gas. The total amount of fuel gas consumed by the four-in-one furnace per hour is 16000 m 3 . In this way, when the device operates normally for 1 year, the total amount of fuel gas required is as high as 140160000 m 3 , calculated at an average fuel gas price of 3 yuan / m 3 . Just the four-in-one heating furnace of a 2.6 million-ton / year continuous reforming unit burns more than 420 million yuan worth of fuel gas every year. With such a huge energy consumption, if the thermal efficiency of the heating furnace can be increased by 1%, the energy-saving effect will be very remarkable! It is very meaningful for the country, the enterprise, and the people. Therefore, the energy-saving control system of the heating furnace makes full use of existing scientific and technological means to conduct all-round and refined control of the heating furnace in the gas chemical plant, enabling the heating furnace to operate in the best fuel consumption state and achieving the maximum energy-saving effect. If thousands of heating furnaces across the country can adopt this advanced control system, it will save a huge amount of energy consumption for the country and the enterprise, making an important contribution to the country's energy conservation and emission reduction and industry upgrading.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. An energy-saving control system for a heating furnace, characterized in that: It includes a DCS control system, a main unit, an operation station, an engineer station, a flue gas analyzer, a flue gas CO analysis sensor, a flue gas O2 analysis sensor, a temperature sensor, a pressure sensor, an actuator, an optical fiber temperature measurement system, and a temperature measurement optical fiber; the main unit is connected to the upper DCS control system; the operation station and the engineer station are respectively connected to the main unit; the flue gas analyzer and the optical fiber temperature measurement system are respectively connected to the main unit; the flue gas CO analysis sensor and the flue gas O2 analysis sensor are respectively connected to the flue gas analyzer; the temperature measurement optical fiber is connected to the optical fiber temperature measurement system; the actuator is connected to the main unit; The optical fiber temperature measurement system is installed by flange, and the optical fiber connection nozzle is installed on the upper surface of the inlet and outlet furnace tubes of the heating furnace. A cut-off gate valve is provided above the optical fiber connection nozzle. In the inlet and outlet furnace tubes of the heating furnace, an optical fiber protection sleeve is buried in advance; the optical fiber self-sealing device is installed on the optical fiber connection nozzle, and the temperature measurement optical fiber is installed through the optical fiber self-sealing device, and the temperature measurement optical fiber is inserted into the optical fiber protection sleeve; Within the optical fiber length of the temperature measurement optical fiber, non-stop temperature measurement is carried out every 25 cm; The optical fiber temperature measurement system measures various temperature data inside the furnace tube through the temperature measurement optical fiber and transmits them to the main unit. The main unit generates a furnace tube heating curve and a furnace tube length temperature difference curve. The furnace tube heating curve includes the dimensions of temperature and time, and the furnace tube length temperature difference curve includes the two dimensions of temperature and furnace tube length. The furnace tube heating curve is used for the establishment of the automatic model of the heating furnace, and the furnace tube length temperature difference curve is used for the calculation, alarm and interlock of the coking thickness of the heating furnace tube; The main unit monitors the real-time temperature and temperature difference of the medium inside the furnace tubes entering and leaving the heating furnace. When the furnace tube length temperature difference curve changes, it automatically calculates the coking thickness of the furnace tube. When the coking thickness of the furnace tube exceeds the alarm value required by the process, the main unit sends an alarm signal to the DCS control system.

2. The energy-saving control system of the heating furnace according to claim 1, characterized in that: The actuator includes a chimney regulating baffle and a furnace bottom pneumatic air damper; the pressure sensor detects the pressure of the convective chamber of the heating furnace furnace, and the main unit controls the chimney regulating baffle according to the pressure of the convective chamber of the furnace; the flue gas O2 analysis sensor detects the O2 content of the flue gas in the chimney of the heating furnace, and the main unit controls the opening of the furnace bottom pneumatic air damper according to the O2 content of the flue gas.

3. The energy-saving control system for a heating furnace according to claim 1, wherein: The main unit controls the actuator according to the detected temperature, pressure, flue gas O2 content, flue gas CO content, furnace tube heating curve, and the fuel gas flow rate of the heating furnace, and establishes an optimal combustion heating model for the heating furnace.

4. The energy-saving control system for a heating furnace according to claim 1, characterized in that: The actuator includes an induced draft fan and a blower; the main unit controls the frequency conversion of the induced draft fan according to the pressure of the convective chamber of the furnace and controls the frequency conversion of the blower according to the O2 content of the flue gas in the chimney.

5. The energy-saving control system for a heating furnace according to claim 1, wherein: The actuator participates in the interlock setting; the signal input / output cards participating in the interlock are redundantly designed, and the controller is also redundantly designed.

6. The energy-saving control system for a heating furnace according to claim 1, wherein: An automatic ignition device and a pilot flame monitoring device are installed on the burner of the heating furnace; the main unit automatically ignites the pilot lamp through the automatic ignition device and monitors the pilot lamp flame information through the pilot flame monitoring device.

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