Direct-fired heating device for denitrification system

Abstract

The present invention is a direct-fired heating device for a denitration system, comprising a plurality of flame burners, each of which is used to directly heat and heat the flue gas; the plurality of flame burners constitute at least two burner groups; the center line of the flame stream of each flame burner of each burner group is tangent to an imaginary tangent circle, and the cutting directions of two adjacent burner groups are oppositely arranged; the flame injection direction of each flame burner is arranged opposite to the direction of the flue gas flow, and the flame injection length is adjustable; the central axis of each flame burner is arranged at an adjustable first angle to the horizontal direction, and the central axis of each flame burner is arranged at an adjustable second angle to the vertical direction. The present invention directly heats the flue gas, causes the flue gas temperature to reach the temperature range of the ideal denitration reaction of the catalyst, realizes the expected denitration reaction, meets the ultra-low emission requirements, and improves the economic benefits of equipment operation.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas denitration, and in particular to a direct-fired heating device for a denitration system. Background Art

[0002] The control of air pollution is an important part of environmental governance. With the development of industry and the improvement of living standards, people are paying more and more attention to environmental issues and atmospheric environmental protection issues.

[0003] Nitrogen oxides (NOx) are a major type of atmospheric pollutant and one of the main factors in the formation of acid rain, photochemical smog and PM2.5 pollution. At present, industrial sources of NOx emissions in my country account for more than 70% of the total NOx emissions. The control emission technologies of NOx in industrial flue gas mainly include combustion control technology and post-combustion control technology. Combustion control technology includes low-nitrogen combustion technology, reburning technology and flue gas recirculation technology. Among the post-combustion control technologies, selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and SCR-SNCR hybrid technology are the main technologies. Considering economic and technical benefits, selective catalytic reduction is the most effective NOx post-control technology.

[0004] The coal combustion process will produce a large amount of air pollutants such as SO2 and NOx, causing serious air pollution and economic losses. The pollutants in the flue gas emitted by thermal power, steel and other industries are diverse, and strict requirements are put forward for the emission of NOx. The purpose of denitrification is mainly to remove nitrogen monoxide (NO) and nitrogen dioxide (NO2).

[0005] The proportion of nitric oxide (NO) in flue gas to nitrogen oxide (NOx) is very high, often above 90%. Nitric oxide is a polluting gas. When it is directly discharged into the atmosphere, it is easy to pollute the atmosphere, soil and water sources. Therefore, when factories discharge flue gas, especially when the flue gas contains nitric oxide, they need to denitrify the flue gas. Among them, the existing flue gas denitrification technologies are mainly dry and wet. Compared with the wet flue gas denitrification technology, the main advantages of dry flue gas denitrification technology are: low basic investment, simple equipment and process, high efficiency of removing NOx, no wastewater and waste treatment, and not easy to cause secondary pollution.

[0006] The completion of the SCR reaction requires the use of a catalyst. Currently, the most widely used is a medium-temperature catalyst with an operating temperature of 320 to 450°C, so the reaction temperature of catalytic reduction denitrification should be controlled at 320 to 450°C. When the reaction temperature is lower than 300°C, side reactions will occur on the catalyst surface. Ammonia reacts with sulfur trioxide and water to generate (NH4)2SO4 or NH4SO4 to reduce the reaction with NOx. The product adheres to the catalyst surface, blocking the catalyst channels and micropores, reducing the catalyst activity. In addition, if the reaction temperature is higher than the applicable temperature of the catalyst, the catalyst channels and micropores will deform, thereby deactivating the catalyst. Therefore, ensuring the appropriate reaction temperature is the key to the normal operation of the selective catalyst reduction method. Low boiler load or low atmospheric temperature will cause the SCR inlet temperature to be lower than the catalyst operating temperature. Among them, SCR denitrification requires a temperature window of 300 to 400°C. NOx is reduced to N2 under the action of the catalyst and NH3, and the denitrification efficiency can reach more than 90%.

[0007] In the denitrification process, the flue gas needs to be heated to a preset temperature before the denitrification process can be carried out efficiently and stably. In the prior art, the flue gas heating is often achieved by setting a heating source below the denitrification flue and allowing the high-temperature gas to rise and mix evenly with the flue gas to achieve the heating purpose. However, since the denitrification system pipelines are generally long in size, heat loss is inevitably caused during the rising process of the high-temperature gas below the mixing layer. At the same time, during the rising process of the high-temperature gas, the axial mixing length with the flue gas is long enough, but the radial mixing surface cannot be guaranteed to be large enough, so the complete and uniform mixing of the high-temperature gas and the flue gas cannot be guaranteed.

[0008] In the steel, metallurgy and coal chemical industries, the exhaust gas temperature of sintering machines and other equipment is relatively low. In order to meet the subsequent denitrification treatment or other process requirements in the SCR equipment, the exhaust gas needs to be heated. There are many ways to heat the flue gas, such as directly adding a heat exchanger, setting up electric heating, etc., which use high-temperature heat sources for heating. These methods require additional heat sources, resulting in high operating costs.

[0009] In addition, since a large amount of blast furnace gas, converter gas, coke oven gas and other fuel gases are usually generated in industrial equipment in the steel, metallurgy and coal chemical industries. Therefore, in the prior art, many companies will use these fuel gases to set up a separate heating furnace outside the flue, and set up one or more blast furnace gas or coke oven gas burners according to the power of the heating furnace. The fuel gas in the burner is burned to produce high-temperature flue gas, and the high-temperature flue gas is sent into the flue through a branch and mixed with the original flue gas in the flue to achieve heating of the original flue gas. Since the above method needs to set up a separate heating furnace outside the flue, on the one hand, the investment cost is relatively high, and on the other hand, after the high-temperature flue gas after the combustion of the fuel gas is mixed with the original flue gas in the flue, the total amount of flue gas in the flue will increase sharply, thereby causing a greater impact on the flue system, and also causing the problem of insufficient output of the existing induced draft fan.

[0010] At present, the environmental protection situation in the steel industry is becoming increasingly severe, and steel companies need to carry out ultra-low emission transformation in steps. The most commonly used technology in steel plants that have implemented low-emission transformation is to build a set of SCR denitrification equipment, and then use the steel plant's own blast furnace gas to heat the flue gas, so as to meet the denitrification inlet flue gas temperature requirements.

[0011] Blast furnace gas is not easy to ignite due to its low calorific value. Generally, an insulated ignition duct with a separate castable is used. Natural gas or light oil gun is used for ignition first. After the temperature in the ignition duct is raised, blast furnace gas is introduced for combustion. Finally, the high-temperature flue gas after combustion is mixed into the denitrification flue to heat the denitrification flue gas. Although blast furnace gas has a low calorific value, it burns in an insulated flue, and the high-temperature flue gas it produces can reach a temperature of 1200-1400°C. During the ignition process, if natural gas or an oil gun is used for ignition, the combustion temperature will be even higher, reaching 1500-1700°C, while the operating temperature of ordinary refractory castables is around 1300°C, which can easily cause the ignition air duct castable to fall off, and then the air duct steel plate will be deformed by high temperature and its life will be shortened; if refractory castables with better performance, such as alumina hollow ball castables, are used, the manufacturing cost will be greatly increased due to their high price; in addition, there is also the prior art that uses a large excess air coefficient to reduce the combustion flue gas temperature, but this method will greatly increase the additional air required for heating, thereby requiring more gas, resulting in poor economic efficiency.

[0012] In the prior art, there is a direct-fired temperature-rising heating device for a denitrification system (CN 209501296 U), and there is also a flue gas heating system (CN 210069874 U). In both, the direct-fired furnaces are arranged in a counter-hedge manner, the flame combustion area is relatively fixed, and the flue gas heating area is small, and it is impossible to heat a flue with a large cross-section. The temperature of the area close to the flame area of ​​the direct-fired furnace is higher, and the temperature of the area close to the walls around the flue is lower. The airflow mixing effect on the cross-sectional axis is poor, which is not conducive to the rapid transfer and uniform distribution of heat.

[0013] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a direct-fired heating device for a denitrification system to overcome the defects of the prior art. Summary of the invention

[0014] The purpose of the present invention is to provide a direct-fired heating device for a denitrification system to overcome the problems existing in the prior art. The device directly heats the flue gas, causing the flue gas temperature to reach the temperature range of the ideal denitrification reaction of the catalyst, thereby realizing the expected denitrification reaction, meeting the ultra-low emission requirements, and improving the economic benefits of equipment operation.

[0015] The objective of the present invention is achieved in this way. A direct-fired heating device for a denitrification system comprises a plurality of flame burners penetrating the side wall of a denitrification flue, each of the flame burners being used to directly heat and raise the temperature of the flue gas; the plurality of flame burners constitute at least two burner groups; the center line of the flame stream of each flame burner of each burner group is tangent to an imaginary tangent circle, and the center line of each flame stream of two adjacent burner groups is opposite to the cutting direction of the imaginary tangent circle; the flame injection direction of each flame burner is opposite to the flue gas flow direction, and the flame injection length of each flame burner is adjustable; the central axis of each flame burner is arranged at an adjustable first angle to the horizontal direction, and the central axis of each flame burner is arranged at an adjustable second angle to the vertical direction.

[0016] In a preferred embodiment of the present invention, the direct-fired heating device for the denitration system also includes a control system.

[0017] In a preferred embodiment of the present invention, each of the flame burners includes a combustion-stabilizing flue structure, a flame injection port is arranged at the first end of the combustion-stabilizing flue structure, and the central axis of the combustion-stabilizing flue structure constitutes the central axis of the flame burner; the second end of the combustion-stabilizing flue structure is connected to a combustion-supporting chamber and a combustion gas chamber; a first rotating structure is connected to the side wall of the combustion-stabilizing flue structure, and the first rotating structure is used to drive the combustion-stabilizing flue structure to swing to adjust the first angle; a second rotating structure is connected to the top of the combustion-stabilizing flue structure, and the second rotating structure is used to drive the combustion-stabilizing flue structure to swing to adjust the second angle.

[0018] In a preferred embodiment of the present invention, the first rotating structure includes a rotating frame, a first reducer and a first motor, and the first reducer and the first motor are both electrically connected to the control system; the rotating frame is fixedly mounted on the stable combustion flue structure, the rotating frame is hinged on a fixed bracket, the first reducer is connected to the fixed bracket through a first flange, the first motor is connected to the rotating frame through the first reducer, and the first motor can drive the rotating frame to rotate to adjust the first angle.

[0019] In a preferred embodiment of the present invention, the second rotating structure includes a rotating support, a second reducer and a second motor, and the second reducer and the second motor are both electrically connected to the control system; the rotating support is fixedly connected to the top of the stable combustion flue structure, the second reducer is connected to the top of the rotating support through a second flange, and the second motor is connected to the rotating support through the second reducer, and the second motor can drive the rotating support to rotate to adjust the second angle.

[0020] In a preferred embodiment of the present invention, a burner through hole is arranged on the side wall of the denitrification flue, the combustion-stabilizing flue structure passes through the burner through hole, and the diameter of the burner through hole is larger than the diameter of the combustion-stabilizing flue structure; a third flange is sleeved on the side wall of the combustion-stabilizing flue structure, one end of the bellows is connected to the third flange, and the other end of the bellows is connected to the fourth flange, the fourth flange is sealed and connected to the side wall of the denitrification flue outside the burner through hole, and the third flange, the bellows and the fourth flange constitute an elastic connection sealing cover of the burner.

[0021] In a preferred embodiment of the present invention, a combustion stabilizing center hole is axially provided on the combustion stabilizing flue structure, the combustion stabilizing center hole constitutes a combustion mixing chamber, an igniter is provided in the combustion mixing chamber, and the igniter is electrically connected to the control system; a combustion-supporting gas inlet is connected to the combustion-supporting gas chamber, and a gas inlet is connected to the gas chamber; an ejector is provided in the gas chamber and the combustion-supporting gas chamber, the ejector is coaxially provided with the combustion stabilizing flue structure, the ejector is used to accelerate the combustible gas in the gas chamber to be sprayed into the combustion mixing chamber, a necked ejection channel is formed between the combustion-supporting gas chamber and the combustion mixing chamber, and the combustion-supporting gas in the combustion-supporting gas chamber is ejected into the combustion mixing chamber through the ejection channel.

[0022] In a preferred embodiment of the present invention, the combustion stabilizing flue structure includes a combustion stabilizing inner tube and a combustion stabilizing outer tube that are coaxially and radially spaced apart, the cross-section of the combustion stabilizing inner tube being a closed contour formed by splicing multiple circular arcs, the cross-section of the combustion stabilizing outer tube being a circle, a combustion stabilizing annular space is formed between the combustion stabilizing inner tube and the combustion stabilizing outer tube, and the combustion stabilizing annular space is filled with a refractory castable material unit.

[0023] In a preferred embodiment of the present invention, a flame detector and a temperature detector are arranged in the combustion mixing chamber, and both the flame detector and the temperature detector are electrically connected to the control system; the flame detector is used to detect the flame burning condition in the combustion mixing chamber, and the temperature detector is used to detect the temperature in the combustion mixing chamber.

[0024] In a preferred embodiment of the present invention, the ejector includes a straight pipe section, a contraction section, a throat section, an expansion section and a straightening section, the straight pipe section is located in the fuel gas chamber, the contraction section, the throat section, the expansion section and the straightening section are located in the combustion-supporting gas chamber; an air inlet is provided at the first end of the straight pipe section, the second end of the straight pipe section is connected to the first end of the contraction section, the diameter of the contraction section is gradually contracted from the first end to the second end, the second end of the contraction section is connected to the first end of the throat section, the second end of the throat section is connected to the first end of the expansion section, the diameter of the expansion section is gradually expanded from the first end to the second end, the second end of the expansion section is connected to the first end of the straightening section, and the second end of the straightening section is provided with an air outlet.

[0025] In a preferred embodiment of the present invention, the rectifying section includes a rectifying inner tube and a rectifying outer tube which are coaxially and radially spaced apart, the cross-section of the rectifying inner tube is a closed contour formed by splicing multiple arc segments, the cross-section of the rectifying outer tube is a circle, a rectifying annular space is formed between the rectifying inner tube and the rectifying outer tube, and the rectifying annular space is filled with a refractory castable material unit.

[0026] In a preferred embodiment of the present invention, the first angle ranges from 10° to 50°, and the second angle ranges from 15° to 85°.

[0027] In a preferred embodiment of the present invention, the denitrification flue is a rectangular flue and is arranged vertically, and two of the burner groups are arranged on two opposite side walls of the denitrification flue, each of the burner groups includes four of the flame burners, and each of the flame burners constitutes an octagonal double-cut circle combustion structure.

[0028] As described above, the direct-fired heating device for a denitration system provided by the present invention has the following beneficial effects:

[0029] (1) In the direct-fired heating device for the denitration system of the present invention, a plurality of flame burners are arranged in groups in the denitration flue, and the heat of the flame combustion of the flame burners is used to directly heat the flue gas, thereby improving the heat utilization efficiency and reducing heat loss;

[0030] (2) Multiple flame burners in the denitrification flue are grouped to form independent swirl zones, achieving a dynamic swirl effect of the flue gas, promoting turbulent flow of the flue gas, promoting heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange zone in the flue, and achieving temperature uniformity; the flame burners carry out efficient combustion of combustible gas and combustion-supporting air, and utilize the jet swirl effect of multiple flame burners to promote rapid mixing and heat exchange between high-temperature gas and flue gas;

[0031] (3) The flame jet direction of the flame burner is arranged opposite to the direction of the flue gas flow, which promotes rapid and efficient heat exchange between the flue gas and the high-temperature flame, shortens the time required for heat exchange, reduces the length of the flue required for uniform flue gas temperature, and promotes uniform temperature in the flue;

[0032] (4) The angle between the central axis of each flame burner and the horizontal and vertical directions can be adjusted to achieve the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and achieve dynamic adjustment of the size and intensity of the swirl area;

[0033] (5) The flame burner adopts ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of equipment operation; the cross-section of the stable combustion inner tube and the rectifier section of the stable combustion flue structure is spliced ​​by multiple arc sections, which increases the contact area between the combustible gas and the combustion-supporting gas, while maintaining the stability of combustion, and achieving a good gathering effect of the jet flame, avoiding premature divergence and attenuation of the flame, ensuring that the flames ejected by multiple flame burners have high kinetic energy, and efficiently stirs the flue gas turbulently to promote heat exchange; at the same time, the multi-arc circular cross-section structure can reduce the local oxygen content of the combustible gas combustion, reduce the local high temperature of the flame burner, avoid the generation of NOx, and achieve low-nitrogen combustion;

[0034] (6) The direct-fired heating device for the denitration system of the present invention directly heats the flue gas, causing the flue gas temperature to reach the temperature range of the ideal denitration reaction of the catalyst, thereby achieving the expected denitration reaction, meeting the ultra-low emission requirements, and improving the economic benefits of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0036] in:

[0037] Figure 1 : It is a schematic diagram of the installation of the direct-fired heating device for the denitration system of the present invention.

[0038] Figure 2 :for Figure 1 Middle AA section view.

[0039] Figure 3 : It is the front view of the outer structure of the flame burner of the present invention.

[0040] Figure 4 : is a side view of the outer structure of the flame burner of the present invention.

[0041] Figure 5 : It is a schematic diagram of the connection between the flame burner of the present invention and the side wall of the denitrification flue.

[0042] Figure 6 : is a cross-sectional view of a flame burner of the present invention.

[0043] Figure 7 :for Figure 6 Center B view.

[0044] Figure 8 : is a schematic diagram of the ejector of the present invention.

[0045] Fig. 9 :for Figure 8 Center C view.

[0046] In the figure:

[0047] 100. Direct-fired heating device for denitration system;

[0048] 1. Flame burner;

[0049] 10. Imaginary tangent circle; 11. Stable combustion flue structure; 111. Stable combustion center hole; 112. Stable combustion inner tube; 113. Stable combustion outer tube; 12. Flame jet port; 13. Third flange; 14. Bellows; 15. Fourth flange; 16. Ignitor; 17. Flame detector; 18. Temperature detector;

[0050] 2. Combustion-supporting gas chamber; 21. Combustion-supporting gas inlet;

[0051] 3. Gas chamber; 31. Gas inlet;

[0052] 4. A first rotating structure;

[0053] 41. rotating frame; 42. first reducer; 43. first motor; 44. fixed bracket; 45. first flange;

[0054] 5. The second rotating structure;

[0055] 51. Rotating support; 52. Second reducer; 53. Second motor; 54. Second flange;

[0056] 6. Ejector;

[0057] 61, straight pipe section; 62, contraction section; 63, throat section; 64, expansion section; 65, rectification section; 651, rectification inner pipe; 652, rectification outer pipe; 66, air inlet; 67, air outlet;

[0058] 7. Refractory casting material unit;

[0059] 9. Denitrification flue;

[0060] 91. front side wall; 92. rear side wall; 93. burner through hole. DETAILED DESCRIPTION

[0061] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0062] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0064] like Figures 1 to 9As shown, the present invention provides a direct-fired heating device 100 for a denitration system, comprising a plurality of flame burners 1 penetrating the side wall of a denitration flue 9, each flame burner 1 being used for directly heating and raising the temperature of the flue gas; the plurality of flame burners 1 constitute at least two burner groups, and the number of the burner groups is an even number; the center line of the flame stream of each flame burner in each burner group is tangent to an imaginary tangent circle, and the center line of each flame stream of two adjacent burner groups is opposite to the cutting direction of the imaginary tangent circle 10; the flame injection direction of each flame burner 1 is arranged opposite to the direction of the flue gas flow, and the flame injection length L of each flame burner 1 is adjustable, and the flame length of the flame burner can be adjusted by adjusting the flow rate and ratio of the combustible gas and the combustion-supporting gas of the flame burner; the central axis of each flame burner 1 is arranged at an adjustable first angle α with the horizontal direction, and the central axis of each flame burner 1 is arranged at an adjustable second angle with the vertical direction; the direct-fired heating device 100 for a denitration system also includes a control system (not shown in the figure).

[0065] The method of directly heating the flue gas in the flue can not only save the amount of flue gas, but also greatly save the engineering cost and the land in the factory. The existing method of directly heating the flue gas in the flue has certain technical difficulties: the negative pressure in the flue is large, and the burner is not easy to burn stably; the flue gas directly in contact with the flame has a high temperature rise, while the flue gas far from the flame has a low temperature rise, so the flue gas temperature is uneven; the scouring of the flame by the flue gas can easily cause the flame to be extinguished; the ignition point of the combustible gas is high, and the inert gas content is high, which is not easy to burn stably. The direct-fired heating device for the denitrification system of the present invention can effectively solve the above problems.

[0066] In the denitration flue of the denitration system, before direct combustion heating, the flue gas flows from top to bottom. The center line of the flame stream of the flame burner in the present invention is oriented toward the direction of the flue gas flow and is arranged opposite to the direction of the flue gas flow (from bottom to top and in an inclined state); Figure 1 As shown, the flame burner 1 is tilted upward, and the flame and the flue gas before heating flow in opposite directions, which increases the turbulence degree of heat exchange between the high-temperature flue gas and the original flue gas, shortens the time required for heat exchange, increases the contact area between the flame and the flue gas, and increases the time for heat exchange between the high-temperature flame and the flue gas, which is beneficial to the uniformity of the flue gas temperature.

[0067] The center line of each flame stream of two adjacent burner groups is set opposite to the cutting direction of the imaginary tangent circle, that is, the center line of each flame stream of two adjacent burner groups and the cutting direction of the imaginary tangent circle adopt the opposite swirl mode, eliminating the impact of the two groups of swirl flame burners and realizing the stable operation of the swirl. The number of burner groups is an even number to ensure the stable operation of the heating device.

[0068] The flame spray length of each flame burner 1 can be adjusted, the diameter of the imaginary tangent circle tangent to the center line of the flame flow of each flame burner in each burner group is different, and the height position of the imaginary tangent circle is different. Different swirl mixing area controls can be achieved under different flue gas flow conditions. The position of the high temperature zone of the flame in the flue is adjustable to achieve dynamic adjustment of the flue gas mixing.

[0069] In the denitration system, a temperature detection device is arranged downstream of the SCR denitration catalyst to detect the actual temperature of the flue gas undergoing the denitration reaction. If the temperature is within the process requirement range, there is no need to adjust the flow rate and ratio of the flame burner. If the temperature is lower than the process requirement, the combustion calorific value of the flame burner is increased to further increase the flue gas temperature. If the temperature is higher than the process requirement, the combustion calorific value of the flame burner is reduced to further reduce the flue gas temperature. The combustion heat released by the flame burner is feedback-controlled through the temperature detection device to control the flue gas temperature within the optimal temperature range of the denitration reaction.

[0070] In the direct-fired heating device for the denitrification system of the present invention, a plurality of flame burners are arranged in groups in the denitrification flue, and the heat of the flame combustion of the flame burners is used to directly heat the flue gas, thereby improving the utilization efficiency of heat and reducing heat loss; the plurality of flame burners in the denitrification flue are grouped to form an independent swirl zone, thereby realizing the dynamic swirl effect of the flue gas, promoting the turbulent flow of the flue gas, promoting the heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange zone in the flue, and realizing temperature uniformity; the flame injection direction of the flame burner is arranged opposite to the direction of the flue gas flow, thereby promoting the rapid and efficient heat exchange between the flue gas and the high-temperature flame , shortening the time required for heat exchange, reducing the flue length required for uniform flue gas temperature, and promoting uniform temperature in the flue; the angle between the central axis of each flame burner and the horizontal and vertical directions can be adjusted to realize the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and realize dynamic adjustment of the size and intensity of the swirl area; the direct-fired heating device for the denitrification system of the present invention directly heats the flue gas, prompting the flue gas temperature to reach the temperature range of the ideal denitrification reaction of the catalyst, realize the expected denitrification reaction, meet the ultra-low emission requirements, and improve the economic benefits of equipment operation.

[0071] Furthermore, the first angle α is in the range of 10° to 50°, preferably in the range of 15° to 30°; the second angle is in the range of 15° to 85°, preferably in the range of 30° to 65°.

[0072] Further, if Figure 2As shown, the denitrification flue 9 is a rectangular flue and is arranged vertically. The center line of the two opposite side walls (front side wall 91 and rear side wall 92) of the denitrification flue 9 is the hedging center line. The flame burners are divided into two groups, each burner group includes four flame burners 1. The flame burners are in the form of tangential combustion. The gas streams of the flame burners are fed in a tangential manner. Each flame burner 1 forms an octagonal double tangential combustion structure. The center line of the flame streams ejected by each group of flame burners is tangent to the same imaginary tangential circle (ellipse or circle), and the rotation directions of the two groups of imaginary tangential circles (ellipse or circle) are opposite, one is clockwise and the other is counterclockwise.

[0073] In actual engineering applications, flame burners can be appropriately added to the front side wall 91 and the rear side wall 92 according to the cross-sectional size of the denitrification flue 9 ; flame burners can also be appropriately added to the other two side walls of the denitrification flue 9 .

[0074] like Figure 2 As shown, in a specific embodiment of the present invention, the angles between the eight flame burners and the side walls of the vertical denitrification flue 9 (i.e., the second angles) are β1, β2, β3, β4, β5, β6, β7, and β8, respectively, ranging from 15° to 85°, and preferably ranging from 30° to 65°.

[0075] Further, if Figure 3 , Figure 4 , Figure 6 As shown, each flame burner 1 includes a combustion-stabilizing flue structure 11, which adopts a cylindrical structure. A flame injection port 12 is arranged at the first end of the combustion-stabilizing flue structure 11, and the central axis of the combustion-stabilizing flue structure 11 constitutes the central axis of the flame burner; a combustion-supporting chamber 2 and a combustion gas chamber 3 are connected to the second end of the combustion-stabilizing flue structure 11; a first rotating structure 4 is connected to the side wall of the combustion-stabilizing flue structure 11, and the first rotating structure 4 is used to drive the combustion-stabilizing flue structure 11 to swing so as to adjust the first angle α; a second rotating structure 5 is connected to the top of the combustion-stabilizing flue structure 11, and the second rotating structure 5 is used to drive the combustion-stabilizing flue structure 11 to swing so as to adjust the second angle.

[0076] Further, if Figure 3As shown, the first rotating structure 4 includes a rotating frame 41, a first reducer 42 and a first motor 43, and the first reducer 42 and the first motor 43 are both electrically connected to the control system; the rotating frame 41 is fixedly mounted on the stable combustion flue structure 11, the rotating frame 41 is hinged on a fixed bracket 44, the first reducer 42 is connected to the fixed bracket 44 through a first flange 45, and the fixed bracket 44 is connected and fixed to the side wall of the denitrification flue 9. The first motor 43 is connected to the rotating frame 41 through the first reducer 42, and the first motor 43 can drive the rotating frame 41 to rotate to adjust the first angle α. The first motor 43 can realize the precise control of the number of motor rotations through an encoder (existing technology), meet the precise setting and control of the rotation angle of the flame burner, and realize the reset of the initial position of the stable combustion flue.

[0077] Further, if Figure 4 As shown, the second rotating structure 5 includes a rotating support 51, a second reducer 52 and a second motor 53, and the second reducer 52 and the second motor 53 are both electrically connected to the control system; the rotating support 51 can be fixedly connected to the top of the stable combustion flue structure 11, the second reducer 52 is connected to the top of the rotating support 51 through the second flange 54, and the second motor 53 is connected to the rotating support 51 through the second reducer 52. The second motor 53 can drive the rotating support 51 to rotate to adjust the second angle. The rotating support 51 and the stable combustion flue structure 11 are connected by welding. The rotating support 51 is connected to the output shaft of the second reducer 52. The second motor 53 is used to drive the rotating support 51 to rotate, and the stable combustion flue structure 11 is driven to rotate in the horizontal plane through the rotation of the rotating support 51. The second motor 53 can realize the precise control of the number of motor rotations through an encoder (existing technology), meet the precise setting and control of the rotation angle of the flame burner, and realize the reset of the initial position of the stable combustion flue.

[0078] The first rotating structure 4 adjusts the first angle α, and the second rotating structure 5 adjusts the second angle, so that the flame jet stream of the flame burner can be dynamically adjusted. The first angle α (the angle between the central axis of each flame burner and the horizontal direction is controlled by controlling the rotation angle of the rotating frame 41) can be accurately set and controlled, and the initial position of the rotating frame 41 can be reset by the control system. The second angle (the angle between the stable combustion flue structure 11 and the vertical direction) can be accurately set and controlled by the number of rotations of the second motor 53 and the initial position of the stable combustion flue structure 11, and the initial position of the stable combustion flue structure 11 can be reset by the control system.

[0079] Further, if Figure 5As shown, a burner through hole 93 is provided on the side wall of the denitrification flue, and the combustion-stabilizing flue structure 11 passes through the burner through hole 93. The diameter of the burner through hole 93 is larger than the diameter of the combustion-stabilizing flue structure 11. In a specific embodiment of the present invention, the distance between the inner wall of the burner through hole 93 and the outer wall of the combustion-stabilizing flue structure 11 is not less than 300 mm (that is, the difference between the radii of the two is not less than 300 mm); the space between the inner wall of the burner through hole 93 and the outer wall of the combustion-stabilizing flue structure 11 can realize the combustion-stabilizing flue structure 11 in the horizontal direction and The vertical rotation realizes the spatial dynamic adjustment of the injection angle (first angle α and second angle) of the high-temperature flame jet of the flame burner; the third flange 13 is sleeved on the side wall of the stable combustion flue structure 11, and the third flange 13 is welded to the stable combustion flue structure 11; the third flange 13 is connected to one end of the bellows 14, and the other end of the bellows 14 is connected to the fourth flange 15. In this embodiment, the length of the bellows 14 is not less than 600mm, and the outlet end of the stable combustion flue structure 11 penetrates the inner wall of the flue side wall by no more than 100mm. The fourth flange 15 is sealed and connected to the denitrification flue side wall outside the burner through hole 93, and the third flange 13, the bellows 14 and the fourth flange 15 constitute the burner elastic connection sealing cover.

[0080] Further, if Figure 6 As shown, a stable combustion center hole 111 is axially provided on the stable combustion flue structure 11, and the stable combustion center hole 111 constitutes a combustion mixing chamber, and an igniter 16 is provided in the combustion mixing chamber, and the igniter 16 is electrically connected to the control system; a combustion-supporting gas inlet 21 is connected to the combustion-supporting gas chamber 2, and a gas inlet 31 is connected to the gas chamber 3; an ejector 6 is provided in the gas chamber 3 and the combustion-supporting gas chamber 2, and the ejector 6 is coaxially provided with the stable combustion flue structure 11, and the ejector 6 is used to accelerate the combustible gas in the gas chamber 3 to be sprayed into the combustion mixing chamber, and a necked ejection channel is formed between the combustion-supporting gas chamber 2 and the combustion mixing chamber, and the combustion-supporting gas in the combustion-supporting gas chamber 2 is ejected into the combustion mixing chamber through the ejection channel. The flame burner 1 adopts ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of the equipment operation. The combustion-supporting gas inlet 21 and the gas inlet 31 are connected to the corresponding pipelines through flanges, and a flow meter and a flow regulating valve are provided on the corresponding pipelines, and the flow meter and the flow regulating valve are electrically connected to the control system. The detection data of the temperature detection device in the denitrification system is used to calculate the required amount of combustible gas and combustion-supporting gas according to the control model, and the flow rate is adjusted through the flow control valve (electric control valve) until the flow rate reaches the predetermined demand.

[0081] The combustion-supporting gas can be connected to the flue gas after the heat exchanger (in the denitrification flue, prior art) in the inlet flue section (existing technology, the entrance of the denitrification flue) through a pipeline, and the flue gas in the original flue is used as the combustion-supporting gas to carry out the combustion reaction of the flame burner, thereby realizing the combustion of the combustible gas under low oxygen concentration conditions, avoiding the production of NOx, and realizing low-nitrogen combustion of the fuel gas.

[0082] The combustible gas entering the flame burner can be blast furnace gas, converter gas, coke oven gas, natural gas, etc., or a mixture of blast furnace gas, converter gas, coke oven gas or natural gas. The combustion-supporting gas entering the flame burner can be air, pure oxygen, or the original flue gas in the flue containing a certain amount of oxygen.

[0083] Further, if Figure 6 , Figure 7 As shown, the stable combustion flue structure 11 includes a stable combustion inner tube 112 and a stable combustion outer tube 113 which are coaxially and radially spaced. The cross section of the stable combustion inner tube 112 is a closed contour formed by splicing multiple arcs, and the number of spliced ​​arcs is preferably an even number; the cross section of the stable combustion outer tube 113 is circular, and a stable combustion annular space is formed between the stable combustion inner tube 112 and the stable combustion outer tube 113, and the stable combustion annular space is filled with a refractory castable material unit 7. The cross section of the stable combustion inner tube 112 is spliced ​​by multiple arcs, which increases the contact area between the high-temperature flame and the flue gas, promotes the heat exchange of the flue gas, and is conducive to maintaining a good gathering effect of the combustion flame, increasing the flame length, and avoiding premature divergence and attenuation of the flame.

[0084] Further, if Figure 6 As shown, a flame detector 17 and a temperature detector 18 are arranged in the combustion mixing chamber, and both the flame detector 17 and the temperature detector 18 are electrically connected to the control system; the flame detector 17 is used to detect the flame burning condition in the combustion mixing chamber, and if the flame is extinguished, the igniter is re-ignited through the control system to achieve stable combustion of the flame burner; the temperature detector 18 is used to detect the temperature in the combustion mixing chamber.

[0085] Further, if Figure 8As shown, the ejector 6 includes a straight pipe section 61, a contraction section 62, a throat section 63, an expansion section 64 and a rectification section 65. The straight pipe section 61 is located in the combustion chamber 3, and the contraction section 62, the throat section 63, the expansion section 64 and the rectification section 65 are located in the combustion-supporting chamber 2; an air inlet pipe port 66 is arranged at the first end of the straight pipe section 61, and the second end of the straight pipe section 61 is connected to the first end of the contraction section 62, and the diameter of the contraction section 62 is gradually reduced from the first end to the second end, and the second end of the contraction section 62 is connected to the first end of the throat section 63, and the second end of the contraction section 62 and the throat section 63 adopt an arc smooth transition, and the second end of the throat section 63 is connected to the first end of the expansion section 64, and the diameter of the expansion section 64 is gradually expanded from the first end to the second end, and the second end of the expansion section 64 is connected to the first end of the rectification section 65, and the second end of the rectification section 65 is provided with an air outlet pipe port 67, and the air outlet pipe port 67 is in the ejection channel.

[0086] In a specific embodiment of the present invention, the length of the expansion section 64 is 6 to 10 times the diameter of the throat section 63, preferably 7 to 9 times, and the length of the straightening section 65 is not less than 100 mm. The distance between the ejector outlet 67 and the bottom of the combustion mixing chamber is between 100 and 300 mm, preferably 150 to 250 mm.

[0087] Further, if Figure 8 , Fig. 9 As shown, the rectifying section 65 includes a rectifying inner tube 651 and a rectifying outer tube 652 which are coaxially and radially spaced apart. The cross section of the rectifying inner tube 651 is a closed contour formed by splicing multiple arc segments, and the cross section of the rectifying outer tube 652 is a circular shape. A rectifying annular space is formed between the rectifying inner tube 651 and the rectifying outer tube 652, and the rectifying annular space is filled with a refractory castable material unit 7.

[0088] The multi-arc circular cross section of the rectifying section 65 can make the combustible gas still maintain the multi-arc circular cross section and spray forward after leaving the gas outlet 67. The multi-arc circular cross section shape increases the contact area between the combustible gas and the combustion-supporting gas, while maintaining the stability of combustion, and achieving a good gathering effect of the sprayed flame, avoiding premature dispersion and attenuation of the flame, ensuring that the flames sprayed by multiple flame burners have high kinetic energy, and efficiently stirring the flue gas in the flue to promote heat exchange. At the same time, the multi-arc circular cross section structure can reduce the local oxygen content of the combustible gas combustion, reduce the local high temperature of the flame burner, avoid the generation of NOx, and achieve low-nitrogen combustion.

[0089] As described above, the direct-fired heating device for a denitration system provided by the present invention has the following beneficial effects:

[0090] (1) In the direct-fired heating device for the denitration system of the present invention, a plurality of flame burners are arranged in groups in the denitration flue, and the heat of the flame combustion of the flame burners is used to directly heat the flue gas, thereby improving the heat utilization efficiency and reducing heat loss;

[0091] (2) Multiple flame burners in the denitrification flue are grouped to form independent swirl zones, achieving a dynamic swirl effect of the flue gas, promoting turbulent flow of the flue gas, promoting heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange zone in the flue, and achieving temperature uniformity; the flame burners carry out efficient combustion of combustible gas and combustion-supporting air, and utilize the jet swirl effect of multiple flame burners to promote rapid mixing and heat exchange between high-temperature gas and flue gas;

[0092] (3) The flame jet direction of the flame burner is arranged opposite to the direction of the flue gas flow, which promotes rapid and efficient heat exchange between the flue gas and the high-temperature flame, shortens the time required for heat exchange, reduces the length of the flue required for uniform flue gas temperature, and promotes uniform temperature in the flue;

[0093] (4) The angle between the central axis of each flame burner and the horizontal and vertical directions can be adjusted to achieve the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and achieve dynamic adjustment of the size and intensity of the swirl area;

[0094] (5) The flame burner adopts ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of equipment operation; the cross-section of the stable combustion inner tube and the rectifier section of the stable combustion flue structure is spliced ​​by multiple arc sections, which increases the contact area between the combustible gas and the combustion-supporting gas, while maintaining the stability of combustion, and achieving a good gathering effect of the jet flame, avoiding premature divergence and attenuation of the flame, ensuring that the flames ejected by multiple flame burners have high kinetic energy, and efficiently stirs the flue gas turbulently to promote heat exchange; at the same time, the multi-arc circular cross-section structure can reduce the local oxygen content of the combustible gas combustion, reduce the local high temperature of the flame burner, avoid the generation of NOx, and achieve low-nitrogen combustion;

[0095] (6) The direct-fired heating device for the denitration system of the present invention directly heats the flue gas, causing the flue gas temperature to reach the temperature range of the ideal denitration reaction of the catalyst, thereby achieving the expected denitration reaction, meeting the ultra-low emission requirements, and improving the economic benefits of equipment operation.

[0096] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A direct-fired heating device for a denitration system, characterized in that: It comprises a plurality of flame burners which are arranged on the side wall of the denitrification flue, each of which is used for directly heating and raising the temperature of the flue gas; the plurality of flame burners constitute at least two burner groups; the center line of the flame stream of each flame burner of each burner group is tangent to an imaginary tangent circle, and the center line of each flame stream of two adjacent burner groups is arranged opposite to the cutting direction of the imaginary tangent circle; the flame injection direction of each flame burner is arranged opposite to the flue gas flow direction, and the flame injection length of each flame burner is arranged in an adjustable manner; the central axis of each flame burner is arranged at an adjustable first angle with the horizontal direction, and the central axis of each flame burner is arranged at an adjustable second angle with the vertical direction; The direct-fired heating device for the denitration system also includes a control system; Each of the flame burners comprises a combustion stabilizing flue structure, a flame injection port is arranged at a first end of the combustion stabilizing flue structure, and a central axis of the combustion stabilizing flue structure constitutes a central axis of the flame burner; The second end of the combustion-stabilizing flue structure is connected to the combustion-supporting chamber and the combustion chamber; a first rotating structure is connected to the side wall of the combustion-stabilizing flue structure, and the first rotating structure is used to drive the combustion-stabilizing flue structure to swing to adjust the first angle; a second rotating structure is connected to the top of the combustion-stabilizing flue structure, and the second rotating structure is used to drive the combustion-stabilizing flue structure to swing to adjust the second angle; A combustion stabilizing center hole is axially provided on the combustion stabilizing flue structure, the combustion stabilizing center hole constitutes a combustion mixing chamber, an igniter is provided in the combustion mixing chamber, and the igniter is electrically connected to the control system; a combustion-supporting gas inlet is connected to the combustion-supporting gas chamber, and a gas inlet is connected to the gas chamber; an ejector is provided in the gas chamber and the combustion-supporting gas chamber, the ejector is coaxially provided with the combustion stabilizing flue structure, the ejector is used to accelerate the combustible gas in the gas chamber to be sprayed into the combustion mixing chamber, a necked ejection channel is formed between the combustion-supporting gas chamber and the combustion mixing chamber, and the combustion-supporting gas in the combustion-supporting gas chamber is ejected into the combustion mixing chamber through the ejection channel; The combustion stabilizing flue structure comprises a combustion stabilizing inner tube and a combustion stabilizing outer tube which are coaxially and radially spaced apart, the cross section of the combustion stabilizing inner tube is a closed contour formed by splicing multiple arc segments, the cross section of the combustion stabilizing outer tube is a circular configuration, a combustion stabilizing annular space is formed between the combustion stabilizing inner tube and the combustion stabilizing outer tube, and the combustion stabilizing annular space is filled with a refractory castable material unit; The ejector comprises a straight pipe section, a contraction section, a throat section, an expansion section and a rectification section, wherein the straight pipe section is located in the combustion chamber, and the contraction section, the throat section, the expansion section and the rectification section are located in the combustion-supporting chamber; an air inlet is arranged at the first end of the straight pipe section, and the second end of the straight pipe section is connected to the first end of the contraction section, and the diameter of the contraction section is gradually contracted from the first end to the second end, and the second end of the contraction section is connected to the first end of the throat section, and the second end of the throat section is connected to the first end of the expansion section, and the diameter of the expansion section is gradually expanded from the first end to the second end, and the second end of the expansion section is connected to the first end of the rectification section, and the second end of the rectification section is provided with an air outlet; The rectifying section comprises a rectifying inner tube and a rectifying outer tube which are coaxially and radially spaced apart. The cross section of the rectifying inner tube is a closed contour formed by splicing multiple arc segments. The cross section of the rectifying outer tube is a circle. A rectifying annular space is formed between the rectifying inner tube and the rectifying outer tube. The rectifying annular space is filled with a refractory castable material unit.

2. The direct-fired heating device for a denitration system according to claim 1, characterized in that: The first rotating structure includes a rotating frame, a first reducer and a first motor, and the first reducer and the first motor are both electrically connected to the control system; the rotating frame is fixedly mounted on the stable combustion flue structure, the rotating frame is hinged on a fixed bracket, the first reducer is connected to the fixed bracket through a first flange, the first motor is connected to the rotating frame through the first reducer, and the first motor can drive the rotating frame to rotate to adjust the first angle.

3. The direct-fired heating device for a denitration system according to claim 2, characterized in that: The second rotating structure includes a rotating support, a second reducer and a second motor, and the second reducer and the second motor are both electrically connected to the control system; the rotating support is fixedly connected to the top of the stable combustion flue structure, the second reducer is connected to the top of the rotating support through a second flange, and the second motor is connected to the rotating support through the second reducer, and the second motor can drive the rotating support to rotate to adjust the second angle.

4. The direct-fired heating device for a denitration system according to claim 1, characterized in that: A burner through hole is arranged on the side wall of the denitrification flue, and the stable combustion flue structure passes through the burner through hole, and the diameter of the burner through hole is larger than the diameter of the stable combustion flue structure; a third flange is sleeved on the side wall of the stable combustion flue structure, and one end of the bellows is connected to the third flange, and the other end of the bellows is connected to the fourth flange, and the fourth flange is sealed and connected to the side wall of the denitrification flue outside the burner through hole, and the third flange, the bellows and the fourth flange constitute an elastic connection sealing cover of the burner.

5. The direct-fired heating device for a denitration system according to claim 1, characterized in that: A flame detector and a temperature detector are arranged in the combustion mixing chamber, and both the flame detector and the temperature detector are electrically connected to the control system; the flame detector is used to detect the flame combustion condition in the combustion mixing chamber, and the temperature detector is used to detect the temperature in the combustion mixing chamber.

6. The direct-fired heating device for a denitration system according to claim 1, characterized in that: The first angle ranges from 10° to 50°, and the second angle ranges from 15° to 85°.

7. The direct-fired heating device for a denitration system according to claim 1, characterized in that: The denitrification flue is a rectangular flue and is arranged vertically. Two burner groups are arranged on two opposite side walls of the denitrification flue. Each burner group includes four flame burners, and each flame burner forms an octagonal double-cut circle combustion structure.

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