CN112710161A - Pure oxygen combustion control system and control method of steel rolling heating furnace - Google Patents
Pure oxygen combustion control system and control method of steel rolling heating furnace Download PDFInfo
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 132
- 238000002485 combustion reaction Methods 0.000 title claims abstract description 106
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 37
- 239000010959 steel Substances 0.000 title claims abstract description 37
- 238000005096 rolling process Methods 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 96
- 239000001301 oxygen Substances 0.000 claims abstract description 96
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 96
- 239000007789 gas Substances 0.000 claims abstract description 64
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000003546 flue gas Substances 0.000 claims abstract description 33
- 239000003034 coal gas Substances 0.000 claims abstract description 29
- 239000003570 air Substances 0.000 claims description 34
- 238000005070 sampling Methods 0.000 claims description 20
- 238000002791 soaking Methods 0.000 claims description 16
- 229910001882 dioxygen Inorganic materials 0.000 claims description 11
- 239000000779 smoke Substances 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 3
- 239000000446 fuel Substances 0.000 abstract description 18
- 230000000694 effects Effects 0.000 abstract description 7
- 238000012937 correction Methods 0.000 abstract description 6
- 238000012544 monitoring process Methods 0.000 abstract description 6
- 238000001514 detection method Methods 0.000 abstract description 5
- 238000012545 processing Methods 0.000 abstract description 2
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000036284 oxygen consumption Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D19/00—Arrangements of controlling devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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Abstract
The invention discloses a pure oxygen combustion control system and a pure oxygen combustion control method for a steel rolling heating furnace, and belongs to the technical field of detection control. The system comprises on-line coal gas, oxygen and flue gas monitoring equipment and data acquisition and processing equipment; the high-speed oxygen lance is arranged beside a burner, air is firstly sent into a heating furnace, and then pure oxygen is sent into the downstream of the flame, so that the first-stage air and fuel are subjected to over-rich combustion, the flame temperature can be effectively reduced, and the generation of thermal NOx is inhibited; the second stage combustion-supporting air is supplemented at the downstream of the flame through the high-speed oxygen lance to form diffuse flameless combustion, and the temperature uniformity of the hearth is improved. The method of the invention adopts a mode of gas component guidance and combustion flue gas generation subsection monitoring and correction, guides combustion operation according to combustion-supporting air ratio determined by gas characteristics, and carries out feedback correction on the combustion-supporting air ratio of each combustion section according to the residual situation of oxygen and combustible components in the combustion flue gas, thereby achieving safe and optimal combustion control effect.
Description
Technical Field
The invention relates to the technical field of detection control, in particular to a pure oxygen combustion control system and a pure oxygen combustion control method for a steel rolling heating furnace.
Background
The heating furnace is important equipment of a steel rolling process, is also a main energy consumption and pollutant discharge device of the steel rolling process, and meets the requirements of a rolling process, and simultaneously achieves the aims of reducing energy consumption, discharge and oxidation burning loss, which are pursued by the production process of the steel rolling heating furnace.
The oxygen-enriched combustion technology is an efficient energy-saving combustion technology, and is mainly characterized in that O in air2The content of N is more than 21 percent till pure oxygen, thereby reducing 79 percent of N which does not participate in combustion reaction in combustion air2Resulting in smoke loss. The oxygen-enriched combustion technology has the following characteristics when being applied to a steel rolling heating furnace:
1) energy is saved, unit fuel consumption is reduced, and heat efficiency is improved. The oxygen-enriched combustion reduces combustion air and combustion waste gas, increases the introduction of effective physical heat in the combustion air, and reduces the heat loss brought away by flue gas, thereby reducing the consumption of ton steel fuel.
2) The heat transfer efficiency is good, and the yield of the heating furnace is high. The oxygen-enriched combustion-supporting can reduce the ignition temperature of the fuel and accelerate the combustion reaction speed; the theoretical combustion temperature of the fuel increases with the increase of the oxygen concentration of the oxygen-enriched air; the oxygen-enriched combustion can improve the content of radioactive gas CO in the combustion products2And H2O, the radiant power of which is 2 times that of the air combustion products.
3) Short heating time and less oxidation burning loss. The heating time and the oxidation burning loss rule in the high-temperature oxygen-enriched combustion process of the walking beam furnace are that the heating time is reduced along with the increase of the oxygen-containing concentration, the higher the oxygen-enriched concentration is, the more complete the combustion is, and the shorter the heating time is. The shorter the time that the surface of the steel billet in the high temperature section is in contact with oxygen and participates in the reaction, the less the scale is generated.
4) Can improve the theoretical combustion temperature of the fuel, and is beneficial to the reasonable utilization of low-calorific-value fuels such as blast furnace gas, producer gas, converter gas and the like.
In 2018, a combustion control system of a 1580 hot rolling heating furnace of a horse steel is transformed by adopting a flameless oxygen-enriched combustion technology, and the implementation effect shows that the heating capacity is improved by more than 15%, the fuel consumption is reduced by more than 15%, the burning loss is reduced by more than 18%, the horse steel becomes a standard pole case which is successfully applied to large-scale steel rolling heating furnaces in the domestic steel industry for the first time in an industrialized mode, and is highly accepted and concerned by the domestic steel industry.
However, in practice, it is found that there are some problems in using pure oxygen to feed into the heating furnace, (1) because the pure oxygen is fed into the heating furnace differently from the conventional oxygen-enriched air, the calculation of the air quantity and the oxygen quantity cannot use the calculation formula under the conventional oxygen-enriched condition, and the redesign is needed, so as to calculate the air quantity and the oxygen quantity of each section of the heating furnace under the pure oxygen condition. (2) When the pure oxygen is used in production, the safety problem is especially required to be noticed, and if the oxygen and gas flow is not controlled, or the control is not reasonable or even wrong, great safety accidents, such as explosion and the like, can be caused, thereby causing great damage to the safety of equipment and personnel.
Through retrieval, the Chinese patent application number: ZL201811436118.3, application date is: 11 and 28 months in 2018, the invention name is: a pure oxygen flue gas circulation heating furnace control system and its control method, the system of this application includes the heating furnace, the heating furnace connects with oxygen pipeline, circulation flue gas pipeline, high calorific value gas pipeline and low calorific value gas pipeline separately through the many fuel burners; and the oxygen in the oxygen pipeline and the circulating flue gas in the circulating flue gas pipeline are mixed in the multi-fuel burner to form combustion-supporting gas, the combustion-supporting gas enters the heating furnace, and the comprehensive oxygen concentration of the combustion-supporting gas is controlled by different coal gas heat values in the high-heat-value coal gas pipeline or the low-heat-value coal gas pipeline. The heating furnace control system of this application adopts the mode that pure oxygen and flue gas circulation combine, realizes that combustion-supporting gas synthesizes oxygen concentration adjustable through the flow of control circulation flue gas and oxygen. However, in this application, the circulating flue gas and the oxygen are mixed for combustion, and the oxygen consumption cannot be accurately calculated in the subsequent process, so that the subsequent combustion cannot be accurately controlled, and the complete combustion cannot be ensured.
Disclosure of Invention
1. Technical problem to be solved by the invention
In view of the problems that the pure oxygen combustion of the existing heating furnace lacks an accurate control method, and the complete fuel combustion cannot be ensured and the safe application of the pure oxygen cannot be ensured, the pure oxygen combustion control system and the control method of the steel rolling heating furnace accurately calculate the oxygen demand of the fuel, continuously detect and adjust the oxygen demand in the subsequent process, ensure the full combustion of the fuel and ensure the safety of personnel.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention discloses a pure oxygen combustion control system of a steel rolling heating furnace, which comprises a heating furnace, wherein the heating furnace is divided into four heating sections from an inlet to an outlet, namely a preheating section, a heating first section, a heating second section and a soaking section; the system also comprises an air main pipe, an oxygen main pipe, a gas analyzer and a flue gas analyzer; the air main pipe is respectively connected into four heating sections of the heating furnace through air branch pipes; the oxygen main pipe is respectively connected into four heating sections of the heating furnace through oxygen branch pipes; the gas main pipe is respectively connected into four heating sections of the heating furnace through gas branch pipes; the gas analyzer is communicated with the gas main pipe through a gas sampling pipe; the flue gas analyzer is connected to the heating furnace through a flue gas sampling tube.
Furthermore, one end of the oxygen branch pipe connected to the heating furnace is provided with a high-speed oxygen lance; one end of the coal gas branch pipe connected to the heating furnace is provided with a burner; the position of the burner is close to the high-speed oxygen lance.
Furthermore, sampling holes are formed in the inlet of the heating furnace, the preheating section, the heating section and the heating section, and the flue gas sampling tube is respectively connected to the inlet of the heating furnace, the preheating section, the heating section and the heating section through the sampling holes.
Furthermore, the air branch pipe, the oxygen branch pipe and the coal gas branch pipe are provided with electromagnetic valves and flow meters; the electromagnetic valve and the flowmeter are electrically connected with the processor through signal lines; the processor is also electrically connected with the gas analyzer and the flue gas analyzer through signal wires.
The invention discloses a control method for pure oxygen combustion of a steel rolling heating furnace by using the system, which comprises the following steps:
step one, calculating the required combustion-supporting air quantity and the required combustion-supporting oxygen quantity after pure oxygen is fed;
step two, presetting O in smoke components of each heating section2And CO content control range;
step three, detecting and comparing O in the hearth2And CO content, judging whether the combustion deviates from the state; when O is present2Judging that the air is excessive when the CO exceeds the set range, and judging that the gas is excessive when the CO exceeds the set range;
and step four, controlling the temperature within a set range, and adjusting the flow of air, oxygen and coal gas according to the temperature change.
Furthermore, in the second step, the ratio of CO: 0 to 100ppm, O2<3.0 percent; heating the CO in the first stage<1000ppm、O2: 0.5 to 1.0 percent; heating CO in two stages<1000ppm、O2: 1.0% -2.0%; CO in the soaking section: 1000 to 3000ppm, O2<0.5％。
Furthermore, in the fourth step, the first step,
1) when the control temperature is in the set range, if O2If the air flow is excessive, the air flow is reduced, namely the air excess coefficient is reduced; if the CO is excessive, reducing the gas flow, namely increasing the air excess coefficient;
2) when the control temperature is higher than the set maximum value, reducing the gas flow and the air flow step by step, and optimizing the combustion state by adjusting the air excess coefficient;
3) and when the control temperature is lower than the set minimum value, increasing the air flow and the coal gas flow step by step, and optimizing the combustion state by adjusting the air excess coefficient.
Furthermore, in the first step, the required theoretical dry air amount is calculated according to the formula (1),
L0＝0.0238(H2+CO)+0.0952×CH4+0.0476×3×CmHn-0.0476×O2 (1)
wherein L is0For theoretical dry air amount, each of the formulaeThe composition represents the volume percentage of the coal gas.
According to the obtained theoretical dry air quantity, the air quantities of the preheating section, the first heating section, the second heating section and the soaking section are respectively calculated by the combination formula (2),
Lair conditioner＝L0×αAir conditioner×T (2)
Wherein L isAir conditionerFor each amount of air, αAir conditionerAnd T is the air excess coefficient of each section, and T is the coal gas quantity of each section.
Since pure oxygen is 5 times of oxygen content in air, the oxygen excess coefficient alphaOxygen gasVariation (air factor excess factor alpha)Air conditionerVariation)/5; calculating the air reduction amount after pure oxygen is added according to the formula (3),
Lair conditioner＝L0×αAir conditionerVariation amount XT (3)
Calculating the pure oxygen increment after pure oxygen is fed according to the formula (4),
Loxygen gas＝L0×αOxygen gasThe variation × T (4).
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) according to the pure oxygen combustion control system of the steel rolling heating furnace, the high-speed oxygen lance is arranged beside the burner, certain air and fuel are fed into the heating furnace for combustion, then the high-speed oxygen lance is used for feeding pure oxygen at the downstream of flame, and pure oxygen flow uniformly reacts when passing through a flame zone, so that first-stage air (alpha is less than 0.8) and all fuel are fed into the furnace for over-rich combustion, the flame temperature can be effectively reduced, and the generation of thermal NOx can be inhibited; the second-stage combustion-supporting air is supplemented at the downstream of the flame through the high-speed oxygen lance, a diffuse flameless combustion form is formed, and the temperature uniformity of the hearth is improved. The problems of theoretical combustion temperature increase, thermal NOx increase, poor temperature uniformity of a hearth and the like caused by the traditional combustion air oxygen enrichment mode are solved.
(2) Because the pure oxygen combustion mode has high safety risk and the combustion control mode is the premise of ensuring the safety of the pure oxygen combustion, the pure oxygen combustion control method of the steel rolling heating furnace adopts the modes of gas component guidance and combustion flue gas sectional monitoring and correction, guides the combustion operation according to the combustion-supporting air ratio determined by the gas characteristics, and carries out feedback correction on the combustion-supporting air ratio of each combustion section according to the residual conditions of oxygen and combustible components in the combustion flue gas, thereby achieving the safe and optimal combustion control effect.
(3) The invention discloses a pure oxygen combustion control method of a steel rolling heating furnace, which is characterized in that the air quantity required by different coal gases is calculated according to the components of the coal gases, and the air quantity and the oxygen quantity introduced are calculated and adjusted according to the difference between the oxygen contents of the pure oxygen and the air, so as to ensure that the fuel can be fully combusted. Meanwhile, furnace gas control of each combustion section adopts a mode of gradually reducing residual oxygen, namely the highest residual oxygen of the preheating section and the weak reducing atmosphere of the soaking section are kept, so that double purposes of reducing oxidation burning loss of steel billets and saving energy are achieved.
Drawings
FIG. 1 is a schematic structural view of a combustion control system of a steel rolling heating furnace according to the present invention;
FIG. 2 is a schematic diagram of the combustion optimization system of the steel rolling heating furnace of the invention.
The reference numbers in the figures illustrate:
1. heating furnace; 11. a preheating section; 12. heating for a first period; 13. heating for the second stage; 14. a soaking section; 21. an air manifold; 22. an air branch pipe; 31. an oxygen main pipe; 32. an oxygen branch pipe; 33. a high-speed oxygen lance; 41. a gas main pipe; 42. a gas branch pipe; 43. burning a nozzle; 5. a gas analyzer; 51. a gas sampling tube; 6. a processor; 61. a signal line; 7. a flue gas analyzer; 71. a flue gas sampling tube; 72. and (4) sampling holes.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Because the pure oxygen combustion mode has high safety risk, the combustion control mode is the premise of ensuring the safety of the pure oxygen combustion, the combustion control mode adopts a coal gas component guidance and combustion produced flue gas segmented monitoring and correction mode, namely: the combustion operation is guided according to the combustion air ratio determined by the coal gas characteristics, and the combustion air ratio of each combustion section is subjected to feedback correction according to the residual conditions of oxygen and combustible components in the combustion flue gas, so that the safe and optimal combustion control effect is achieved. The method of the invention adopts a side-burning oxygen-blowing staged combustion mode, and can flexibly adjust the oxygen proportion, thereby adapting to the influence of the fluctuation of the coal gas heat value and meeting different heating process requirements. The combustion flue gas monitoring and controlling adopts a segmented mode, and can carry out targeted monitoring and adjustment around different process control requirements of each combustion section. Meanwhile, furnace gas control of each combustion section adopts a mode of gradually reducing residual oxygen, namely the preheating section 11 has the highest residual oxygen and the soaking section 14 keeps a weak reducing atmosphere, so that double purposes of reducing oxidation burning loss of steel billets and saving energy are achieved.
Example 1
Referring to fig. 1, the pure oxygen combustion control system of a steel rolling heating furnace of the present embodiment includes a heating furnace 1, wherein the heating furnace 1 is divided into four heating sections from an inlet to an outlet, which are a preheating section 11, a heating section 12, a heating section 13 and a soaking section 14; the device also comprises an air main pipe 21, an oxygen main pipe 31, a coal gas main pipe 41, a coal gas analyzer 5 and a flue gas analyzer 7; the air main pipe 21 is respectively connected into the four heating sections of the heating furnace 1 through the air branch pipes 22; the oxygen main pipe 31 is respectively connected into the four heating sections of the heating furnace 1 through the oxygen branch pipes 32; the gas main pipe 41 is respectively connected into four heating sections of the heating furnace 1 through gas branch pipes 42; the gas analyzer 5 is communicated with the gas main pipe 41 through a gas sampling pipe 51; the flue gas analyzer 7 is connected to the heating furnace 1 through a flue gas sampling pipe 71. Wherein one end of the oxygen branch pipe 32 connected to the heating furnace 1 is provided with a high-speed oxygen lance 33; one end of the coal gas branch pipe 42 connected to the heating furnace 1 is provided with a burner 43. The burner 43 is arranged close to the high-speed oxygen lance 33.
In the embodiment, a side-burning heating mode is adopted, namely, the burner nozzles 43 are arranged on two side surfaces of the furnace body, the high-speed oxygen lance 33 is arranged beside the burner nozzles 43, certain air and fuel are fed into the heating furnace 1 for burning, then the high-speed oxygen lance 33 is used for feeding pure oxygen at the downstream of flame, the pure oxygen flow uniformly reacts when passing through the flame zone, the reaction rate is controlled by controlling the local pressure and temperature of reactants, and the oxygen-enriched burning of 35% -60% is realized. Thus, the first-stage air (alpha is less than 0.8) and all the fuel are fed into the furnace for over-rich combustion, the flame temperature can be effectively reduced, and the generation of thermal NOx can be inhibited; the second-stage combustion-supporting air is supplemented at the downstream of the flame through the high-speed oxygen lance, a diffuse flameless combustion form is formed, and the temperature uniformity of the hearth is improved. The problems of theoretical combustion temperature increase, thermal NOx increase, poor temperature uniformity of a hearth and the like caused by the traditional combustion air oxygen enrichment mode are solved. Meanwhile, each heating section of the embodiment is independently controlled, the heating temperature and the air (oxygen) gas flow ratio can be independently controlled, and the hearth pressure is controlled in a micro-positive pressure state (about 0 to +20 Pa).
In the embodiment, the following functions are realized through the sonic jet of the high-speed oxygen lance 33: firstly, stretching the flame to the middle part of a hearth, and reducing the temperature difference between the end part and the center; and the flameless combustion is realized, the high-temperature area of flame is reduced, and the temperature difference of the whole area is reduced, so that the effects of strengthening heating of the blank and reducing the heating temperature difference of the section are achieved.
Sampling holes 72 are formed in the inlet of the heating furnace 1, the preheating section 11, the heating section 12 and the heating section 13, and the flue gas sampling pipe 71 is connected to the inlet of the heating furnace 1, the preheating section 11, the heating section 12 and the heating section 13 through the sampling holes 72. In this example, O2By electrochemical or thermomagnetic detection, CO, CH4、CO2CmHn is detected by adopting an infrared principle, H2And (4) detecting by adopting a thermal conductivity principle. In order to prevent impurities such as tar, naphthalene and the like in the coal gas from blocking the sampling tube and safely considering, the sampling system is provided with a steam back flushing system, the temperature of steam is 120-180 ℃, and the pressure is not lower than 0.2 MPa. A gas treatment device is arranged in front of the analyzer, so that the purposes of gas washing (water consumption), filtering and drying (activated carbon consumption), cooling and dehydration (the cooling temperature is controlled within 5 ℃), fine dust removal and the like are achieved.
In this embodiment, the air branch pipe 22, the oxygen branch pipe 32 and the gas branch pipe 42 are all provided with electromagnetic valves and flow meters; the electromagnetic valve and the flowmeter are electrically connected with the processor 6 through a signal wire 61; the processor 6 is also connected with the gas branch through a signal wire 61The analyzer 5 is electrically connected with the smoke analyzer 7. All the parts are controlled by the processor 6, and the processor 6 obtains the flow of oxygen, air and coal gas to perform operation processing. The processor 6 collects data transmitted by the on-line gas detection system, calculates theoretical air coefficients in real time, and guides and adjusts the gas quantity and the air (oxygen) quantity of each section in real time according to the control temperature of each section to guide combustion control. Simultaneously, data transmitted from an online smoke detection system are collected in real time according to O2And the change conditions of thermal parameters such as CO and the like, and the theoretical air coefficient is corrected and fed back to optimize combustion control.
Referring to FIG. 2, the pure oxygen combustion control method for a steel rolling heating furnace according to the present embodiment first depends on the dry gas component (O) detected by a gas analyzer2、CO、H2、CH4、CO2CmHn, etc.), the theoretical amount of air for complete combustion of the gas is calculated (1 Nm when the flue gas produced by combustion contains no combustible components and the oxygen content is 03The amount of air required for the gas),
TABLE 1 gas composition table
Substituting the components in Table 1 into formula (1) to calculate the theoretical air quantity L0：
L0＝0.0238(H2+CO)+0.0952×CH4+0.0476×3×CmHn-0.0476×O2 (1)
Wherein L is0The components in the formula represent the volume percentage of the theoretical dry air in the coal gas. To obtain L0＝2.25。
Step one, calculating the required combustion-supporting air quantity and the required combustion-supporting oxygen quantity after pure oxygen is fed:
the air excess coefficient and heating temperature of each section are set as follows:
TABLE 2 setting table for air excess coefficient and heating temperature of each stage
Taking the soaking section as an example, the calculation methods of other heating sections are the same. Setting the gas quantity of the soaking zone to be 5000Nm3The soaking zone air amount is calculated according to equation (2):
Lair conditioner＝L0×αAir conditioner×T (2)
Wherein L isAir conditionerFor each amount of air, αAir conditionerAnd T is the air excess coefficient of each section, and T is the coal gas quantity of each section. The amount of air L in the soaking zoneAir conditioner＝2.25×0.8×5000＝9000Nm3。
The oxygen content in the air is about 21%, and 1Nm can be considered3Oxygen equivalent to 5Nm3The oxygen content of the air. Oxygen excess coefficient αOxygen gasVariation (air factor excess factor alpha)Air conditionerVariation)/5; calculating the air reduction amount after pure oxygen is added according to the formula (3),
Lair conditioner＝L0×αAir conditionerVariation amount XT (3)
And the pure oxygen increment after pure oxygen input is calculated according to the formula (4),
Loxygen gas＝L0×αOxygen gasVariation amount XT (4)
If the air coefficient of the soaking section is excessive coefficient alphaAir conditionerFrom 0.8 to 0.6, the oxygen excess coefficient αOxygen gasCorresponding increase of (0.8-0.6)/5 equals to 0.04, the air quantity before oxygen enrichment administration equals to 2.25 × 0.8 × 5000 equals to 9000Nm3(ii) a The amount of air L after oxygen enrichmentAir conditioner＝2.25×0.6×5000＝6750Nm3Oxygen amount LOxygen gas＝2.25×0.04×5000＝450Nm3. Namely: when the first stage combustion air quantity is reduced from 9000 to 6750Nm3The amount of the secondary combustion-supporting oxygen needs to be increased by 450Nm3。
Step two, presetting O in smoke components of each heating section2And CO content control range:
setting CO in the preheating section: 0 to 100ppm, O2<3.0 percent; heating the CO in the first stage<1000ppm、O2: 0.5 to 1.0 percent; heating CO in two stages<1000ppm、O2: 1.0% -2.0%; CO in the soaking section: 1000～3000ppm、O2<0.5％。
Step three, detecting and comparing O in the hearth2And CO content, judging whether the combustion deviates from the state; when O is present2Judging that the air is excessive when the CO exceeds the set range, and judging that the gas is excessive when the CO exceeds the set range;
step four, controlling the temperature within a set range, and adjusting the flow of air, oxygen and coal gas according to the temperature change:
1) when the control temperature is in the set range, if O2If the air flow is excessive, the air flow is reduced, namely the air excess coefficient is reduced; if the CO is excessive, reducing the gas flow, namely increasing the air excess coefficient;
2) when the control temperature is higher than the set maximum value, reducing the gas flow and the air flow step by step, and optimizing the combustion state by adjusting the air excess coefficient;
3) and when the control temperature is lower than the set minimum value, increasing the air flow and the coal gas flow step by step, and optimizing the combustion state by adjusting the air excess coefficient.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (10)
1. A pure oxygen combustion control system of a steel rolling heating furnace comprises a heating furnace (1), wherein the heating furnace (1) is divided into four heating sections from an inlet to an outlet, namely a preheating section (11), a heating section (12), a heating section (13) and a soaking section (14); the method is characterized in that: the device also comprises an air main pipe (21), an oxygen main pipe (31), a coal gas main pipe (41), a coal gas analyzer (5) and a flue gas analyzer (7); the air main pipe (21) is respectively connected into four heating sections of the heating furnace (1) through air branch pipes (22); the oxygen main pipe (31) is respectively connected into four heating sections of the heating furnace (1) through oxygen branch pipes (32); the gas main pipe (41) is respectively connected into four heating sections of the heating furnace (1) through gas branch pipes (42); the gas analyzer (5) is communicated with the gas main pipe (41) through a gas sampling pipe (51); the flue gas analyzer (7) is connected to the heating furnace (1) through a flue gas sampling tube (71).
2. The pure oxygen combustion control system of a steel rolling heating furnace according to claim 1, characterized in that: one end of the oxygen branch pipe (32) connected to the heating furnace (1) is provided with a high-speed oxygen lance (33); one end of the coal gas branch pipe (42) connected to the heating furnace (1) is provided with a burner (43); the position of the burner (43) is close to the high-speed oxygen lance (33).
3. The pure oxygen combustion control system of a steel rolling heating furnace according to claim 2, characterized in that: sampling holes (72) are formed in the inlet of the heating furnace (1), the preheating section (11), the heating section (12) and the heating section (13), and the flue gas sampling tube (71) is respectively connected to the inlet of the heating furnace (1), the preheating section (11), the heating section (12) and the heating section (13) through the sampling holes (72).
4. The pure oxygen combustion control system of a steel rolling heating furnace according to claim 2 or 3, characterized in that: the air branch pipe (22), the oxygen branch pipe (32) and the coal gas branch pipe (42) are respectively provided with an electromagnetic valve and a flowmeter; the electromagnetic valve and the flowmeter are electrically connected with the processor (6) through a signal line (61); the processor (6) is also electrically connected with the gas analyzer (5) and the flue gas analyzer (7) through signal wires (61).
5. The method for controlling pure oxygen combustion of a steel rolling heating furnace by using the system of claim 4, which is characterized by comprising the following steps:
step one, calculating the required combustion-supporting air quantity and the required combustion-supporting oxygen quantity after pure oxygen is fed;
step two, presetting O in smoke components of each heating section2And CO content control range;
step three, detecting and comparing O in the hearth2And CO content, judging whether the combustion deviates from the state; when O is present2Judging that the air is excessive when the CO exceeds the set range, and judging that the gas is excessive when the CO exceeds the set range;
and step four, controlling the temperature within a set range, and adjusting the flow of air, oxygen and coal gas according to the temperature change.
6. The pure oxygen combustion control method of a steel rolling heating furnace according to claim 5, characterized in that: in the second step, setting the ratio of CO in the preheating section (11): 0 to 100ppm, O2<3.0 percent; heating CO in a first stage (12)<1000ppm、O2: 0.5 to 1.0 percent; heating CO in the second stage (13)<1000ppm、O2: 1.0% -2.0%; CO in the soaking section (14): 1000 to 3000ppm, O2<0.5％。
7. The pure oxygen combustion control method of a steel rolling heating furnace according to claim 6, characterized in that: in the fourth step, the first step is carried out,
1) when the control temperature is in the set range, if O2If the air flow is excessive, the air flow is reduced, namely the air excess coefficient is reduced; if the CO is excessive, reducing the gas flow, namely increasing the air excess coefficient;
2) when the control temperature is higher than the set maximum value, reducing the gas flow and the air flow step by step, and optimizing the combustion state by adjusting the air excess coefficient;
3) and when the control temperature is lower than the set minimum value, increasing the air flow and the coal gas flow step by step, and optimizing the combustion state by adjusting the air excess coefficient.
8. The pure oxygen combustion control method of a steel rolling heating furnace according to claim 7, characterized in that: in the first step, the required theoretical dry air amount is calculated according to the formula (1),
L0＝0.0238(H2+CO)+0.0952×CH4+0.0476×3×CmHn-0.0476×O2 (1)
wherein L is0Is the theoretical dry air amount, whereinEach component represents its volume percentage in the gas.
9. The pure oxygen combustion control method of a steel rolling heating furnace according to claim 8, characterized in that: according to the obtained theoretical dry air quantity, the combination formula (2) respectively calculates the air quantity of a preheating section (11), a heating section (12), a heating section (13) and a soaking section (14),
Lair conditioner＝L0×αAir conditioner×T (2)
Wherein L isAir conditionerFor each amount of air, αAir conditionerAnd T is the air excess coefficient of each section, and T is the coal gas quantity of each section.
10. The pure oxygen combustion control method of a steel rolling heating furnace according to claim 9, characterized in that: since pure oxygen is 5 times of oxygen content in air, the oxygen excess coefficient alphaOxygen gasVariation (air factor excess factor alpha)Air conditionerVariation)/5; calculating the air reduction amount after pure oxygen is added according to the formula (3),
Lair conditioner＝L0×αAir conditionerVariation amount XT (3)
Calculating the pure oxygen increment after pure oxygen is fed according to the formula (4),
Loxygen gas＝L0×αOxygen gasThe variation × T (4).
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