RU2582722C2 - Vortex furnace - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to swirl furnaces with tangential arrangement of burners. Swirl furnace is divided by double-sided wafer core into afterburner chamber with additional burners and underlying combustion chamber with tangentially installed main burners. Tangential feed of coal dust with primary blowing through burner generates high-temperature combustion core and molten fire flow moving first, bottom and raising in combustion chamber walls as peripheral vortex, which washes roots flames.

EFFECT: invention increases efficiency, widens range of load control.

7 cl, 2 dwg

Description

The invention relates to a semi-open chamber vortex furnace devices with a tangential arrangement of burners, which provides a rotating pulverized coal torch and stable combustion, including coal-containing and other waste, coal in the form of coal-water fuel - VUT. The device can be used in industrial and energy boilers, including when converting them from liquid and gaseous fuels to coal by pre-processing it into a VUT.

Known range fire chamber VTI [Kotler V.R. Special furnaces of power boilers. - M .: Energoatomizdat, 1990, p.17-30.] Semi-open type. The furnace is divided by a two-sided pinch into a combustion chamber and an afterburner located above it and has direct-flow burners, with the main burners installed downwardly inclined at the lower faces of the pinch, and additional burners above them at an angle less than 10 °. Thanks to the counter-inclined placement of the torch, torches are created with loop-shaped trajectories in the form of the letter γ (gamma) passing through the roots of the torches. Impact of flares and supply of high-temperature flue gases to the root of flares provide intense ignition and combustion. Gamma firebox is high temperature, it works with liquid slag removal.

The disadvantages of the VTI gamma furnace are: large emission of harmful emissions and intense slagging caused by high temperature. Gamma fire chamber VTI is not intended for the use of VUT.

Of the known technical solutions, the closest in technical essence to the claimed device, which is selected as a prototype, is a low-temperature vortex furnace - NTV. [Kotler V.R. Special furnaces of power boilers. - M .: Energoatomizdat, 1990, p. 43, Fig. 22]. The NTV contains a combustion chamber, passing in the lower part into a cold funnel, direct-flow burners located on the lower edge of the pinch on the front wall of the combustion chamber and directed downwards, as well as blast nozzles installed in the mouth of the cold funnel directed opposite to the burners. This pair of fuel-air jet streams and the pinch on the front wall form a vortex in the furnace and supply of burning flue gases to the root of the torches, ensure the retention of fuel particles and the low-temperature combustion process - uniform, with its spread into a cold funnel. NTV is characterized by low emission of harmful emissions and is not slagged.

The disadvantages of the prototype are: low profitability, a small range of load regulation and the inability to burn fuel oil. Low profitability arises due to the large mechanical underburning. Indeed, a uniform low temperature level is maintained in a low-temperature furnace; therefore, ignition and burning of particles is slowed down. On the other hand, due to poor retention, the particles are removed from the NTV and burn out poorly, in addition, there is a significant failure at the mouth of the cold funnel. The small range of load regulation is explained by the fact that in the low-temperature furnace of NTV, when working with reduced loads, the temperature level decreases even more, unstable combustion and pulsations occur. Accordingly, for example, with a low summer heating load, the furnace and all equipment must be periodically stopped and started up, which is extremely uneconomical. For this reason, coal, cheap sludge and coal-containing wastes cannot be involved in the fuel balance when they are fed in the form of HLW, since the NTV furnace is unsuitable for their disposal due to low temperature.

The aim of the invention is:

- increase in profitability;

- expanding the range of load regulation;

- involvement of sludge, carbon-containing and other sticky wastes in the fuel balance by feeding and burning them in the form of HLW;

- transfer of industrial and energy gas-oil boilers from liquid and gaseous fuels to coal, through preliminary processing and supply of coal for combustion in the form of high-temperature fuel.

Features of the use of VUT [Zaydenvarg V.E., Trubetskoy K.N., Murko V.I., Nekhoroshiy I.Kh. Production and use of coal water fuel. - M.: Publishing House of the Academy of Mining Sciences, 2001. - 176 p.] Require explanation. Sticky waste: sludge, sludge and wet coal treatment waste are typically represented by micron-sized fine particles. It is proposed that they be processed and fed in the form of HLT pumps and sprayed with nozzles. Thus, it is possible to easily supply sticky streams that cover the fuel path. Since HLW from waste has a low calorific value, below 2500-2900 kcal / kg, and for its ignition and stable burning, high-calorie fuel is required, it is proposed to dispose of HLW from waste together with pulverized coal burning.

On the other hand, coal, for example, by wet grinding can also be converted into HLW, but with a calorie content of more than 3000 kcal / kg. It is proposed to supply coal to the boiler in the form of a fuel-injection pump to replace expensive liquid and gaseous fuels, while theoretically no additional fuel is required for stable combustion. Note that wet grinding does not require a drying agent, drying of coal and is performed regardless of the operation of the boiler.

An important feature of VUT is the need for preliminary drying of drops. Otherwise, the passage of VUT drops to the walls of the furnace will cause them to stick in the form of a fast-growing "coat" filling the volume of the furnace. In addition, in the drying stage, the temperature of the particles slightly exceeds the boiling point of water, 100 ° C, so a significant period of time can elapse before heating and ignition of already dried particles. For boilers when they are transferred to VUT, it is typical: instability, extinction, and tightening of the VUT torch into a superheater with its burnout.

The technical result, which provides a solution to the problem, is expressed in the allocation of a vortex combustion chamber and the creation in its volume of a high-temperature combustion core and a hot burning stream moving from this core downward and rising further along the walls of the combustion chamber upward in the form of a peripheral vortex washing the torch roots and initiating their ignition. In this case, the high-temperature combustion core and the burning peripheral vortex provide:

- increased efficiency - due to ignition and further intensive burning of fuel-air jets in a vortex combustion chamber;

- expanding the range of load control - due to reliable ignition, retention of burning particles under pinch, and stable combustion of the high-temperature core itself, including in gasification mode, even with minimal fuel supply to the vortex combustion chamber, that is, at low boiler load;

- the possibility of involving sludge and carbon-containing waste in the fuel balance with feeding it in the form of HLW, since the high-temperature core of burning the main fuel with washing with the peripheral vortex of the roots of their torches creates conditions for intensive drying, ignition and stable burning of low-calorific HLW;

- the possibility of transferring gas-oil boilers from liquid and gaseous fuels to coal in the form of HLW, since stable burning of HLW can be ensured in reconstructed with the release of a vortex combustion chamber in the furnaces of gas-oil boilers during their operation in gasification mode.

The presence of even the smallest dimensions of a combustion chamber allocated with double-sided clamping with a high-temperature combustion core will always initiate ignition, sustain combustion and flame propagation into the afterburner when additional fuel is supplied through the upper tier, especially when the combustion chamber is in gasification mode and secondary blast is added in the neck area pinch. In this case, the afterburning chamber provides not only the overall high load of the furnace, but also the regulation of the temperature of the steam overheating in the boiler by pulling the combustion torch with the secondary blast stream into the afterburning chamber.

In order to eliminate fuel losses with a failure, additional technical solutions can be used: a afterburning grate and / or lower blast nozzles are installed at the mouth of the cold funnel, overlapping its mouth and oriented in accordance with the rotation of the vortex.

A comparative analysis of the characteristics of the claimed device with the signs of a prototype and analogue indicates the conformity of the claimed technical solution to the criterion of "novelty."

The claimed features solve the following functional tasks.

The sign “the combustion chamber is separated by a double pinch with the main burners installed with a slope downward on the lower faces of the pinch and made with a cold funnel, and the main burners are installed tangentially” ensures that the burning particles are kept under the pinch, forms a high-temperature combustion core and a hot burning stream moving from this core down the axis of the combustion chamber and rising further along its walls upwards in the form of a peripheral vortex washing the roots of the torches, and this ensures:

- increase in efficiency and completeness of fuel burnout;

- expanding the range of load control due to reliable ignition and stable combustion.

The sign “additional burners of the lower tier are located in the area of the neck of the pinch and are connected to the supply lines of the HLW, and they are installed with a slope down and tangentially, their jets cover the jets of the main burners from below” provides the possibility of feeding and involving sludge and coal-containing waste into the fuel balance in the form of HLW . In the combustion chamber, the flows of VUT droplets are washed from above by the torches of the main burners and the high-temperature combustion core, and from below by the oncoming burning stream of the peripheral vortex, therefore they are intensively dried, heated, ignited and burn steadily.

The sign “secondary blast nozzles are located in the area of the pinch neck” increases the efficiency of holding and burning particles by discarding them by the secondary blast jets, allows introducing a two-stage combustion scheme with gasification in the combustion chamber and tightening the vortex plume and generating heat into the afterburner. In this case, all the screens of the vortex furnace perceive heat evenly in height. The temperature of the gases at the outlet of the furnace increases, providing control of the superheat temperature of the steam. Maintaining the superheat temperature of steam in the entire range of load regulation is necessary when the boiler is operating with a turbine.

The sign “additional burners of the upper tier are connected to the supply path of fine coal” provides the overall high load of the furnace and boiler, as well as the regulation of the temperature of the superheat of steam in the entire range of load control.

The signs “there is a afterburning grate at the mouth of the cold funnel” and “on the walls of the cold funnel there are at least one tier of the lower blast nozzles directed to the opposite wall of the cold funnel and oriented in plan in accordance with the direction of the burners” suppress the failure with a failure, further increase the efficiency of the swirl chamber.

The sign “main and additional burners of the lower tier, located in the area of the neck of the pinch, are connected to the supply path of the HLW, with secondary blast nozzles installed in the zone of the neck of the pinch” provides the possibility of feeding and burning coal in the form of HLW, including in gas-oil boilers reconstructed from the separation of the two-sided pinch operating in gasification mode of the vortex combustion chamber. In the combustion chamber, the flows of VUT droplets are washed from above by a burning core, and from below by a burning stream of a peripheral vortex, they are intensively dried and ignited. The main combustion of the VUT torch spreads to the afterburner, the fuel burns in the secondary blast stream coming through nozzles in the area of the pinch neck.

The invention is illustrated by drawings, in Fig.1 shows a cross section and in Fig.2 a longitudinal section of the proposed swirl furnace.

The vortex furnace 1 is divided by a two-sided pinch 2, which is formed by folding the side screens 3 into an afterburner 4 with additional burners of the lower 5 and upper 6 tiers and a combustion chamber located below it 7. The combustion chamber 7 has the main burners installed with a downward inclination on the lower faces of the pinch 8 9 and is made with a cold funnel 10, and the burners 9 are installed tangentially - tangentially to the conditional circle 11 located in the combustion chamber 7.

Additional burners 5 of the lower tier are used to supply fuels and waste in the form of HLW. They are located on the front 12 and rear 13 screens in the region 14 of the neck of the pinch and connected to the supply paths of the fuel-and-chemical assembly. Additional burners 5 of the lower tier are installed, like the main burners, with an inclination downward and tangentially, and their jets cover the jets of the main burners from below, Fig.2. In the region 14 of the neck of the pinch on the front 12 and rear 13 screens are also located nozzles of the secondary blast 15.

Note that the double-sided pinch 2 can be installed on the front and rear screens, and additional burners 5 and secondary blast nozzles 15 on the side screens, and not as shown in figure 1 and figure 2.

Important elements for describing the operation of the furnace are the high-temperature core 16 and the incandescent burning stream of the peripheral vortex 17 rising along the walls of the combustion chamber 7.

In the mouth of the cold funnel 10, in order to reduce losses with a failure, a post-combustion grate 18 can be located, and / or in at least one tier of the lower blast nozzle 19, can be installed on the walls of the cold funnel on the walls of the cold funnel, directed to the opposite wall of the cold funnel and oriented in accordance with the direction of the burners and vortex.

The superheater 20 may include convective and radiation heating surfaces, it is located, as usual, at the exit of the vortex furnace 1 behind the aerodynamic protrusion.

This scheme, FIG. 1 and FIG. 2, can be implemented by reconstruction not only in existing pulverized coal boilers, but also in gas-oil boilers by installing double-sided clamping, afterburning grate and / or lower blast nozzles, as well as an ash removal channel. Moreover, when transferring gas-oil boilers to coal burning due to the typical tightness of the boiler room, a more acceptable solution would be to use coal-fired HLW.

The proposed swirl furnace 1 operates as follows.

The combustion chamber 7, the furnace volume of which includes a cold funnel 10 and is distinguished by a double-sided pinch 2 formed by folding the side shields 3, is used to ignite and stabilize combustion in the furnace with fuel supplied with primary blast through the main burners 9 installed on the lower faces of pinch 8. Important that the combustion chamber 7 can also work in gasification mode with filling its volume with an enriched fuel mixture and supplying the missing air at the outlet through the secondary blast nozzles 15 and burner 6. Stabilization of combustion, including follows using enriched fuel mixture needed to provide the minimum firing loads, as well as the condition of maintaining the operating temperature in the combustion chamber 7 below slagging temperature of its walls.

When considering the operation of a vortex furnace, three options for the fuels used must be considered: pulverized coal; VUT of low quality prepared from sludge and waste when co-incinerated with pulverized coal fuel; high-calorific fuel from coal in the form of VUT.

When the boiler is running on coal, the bulk of the coal is fed through the burners 6 of the upper tier. The combustion chamber 7 works as a combustion stabilizer and allows you to have a low load of the furnace and boiler. The supply of coal dust with primary blast through the main burners 9 tangentially to the circumferential circle 11 located in the combustion chamber 7, creates in this small volume a zone of impact of flares and forms a high-temperature combustion core 16 and an incandescent burning stream, moving down and rising further along the walls of the chamber combustion 7 upward in the form of a peripheral vortex 17. This peripheral vortex 17 washes the roots of the torches, the mouth of the main 9 and additional 5 burners of the lower tier, initiates the intense ignition of their torches. The largest particles can fall out of the vortex stream down. Then they return to the vortex with jets that flow through the nozzles of the lower blast 19 and overlap the cross section of the cold funnel. The failed particles burn out on the afterburning grate 18 located at the mouth of the cold funnel 10.

In gasification mode, the combustion chamber 7 is filled with an enriched combustible mixture of highly reactive products of incomplete combustion, so it can work stably at lower temperatures, this eliminates its slagging. When the supply of the missing air through the nozzles of the secondary blast 15, the torch from the combustion chamber 7 and heat dissipation propagate upward into the afterburner 4. As a result, by supplying the secondary blast, the superheat temperature of the steam in the superheater 20 is controlled.

On the other hand, a torch propagating into the afterburning chamber 4 from the combustion chamber 7 and heat generation allow reliable ignition. Therefore, by changing the coal supply through additional burners 6 of the upper tier to the afterburning chamber 4, it is possible to provide a quick power maneuver and overall high boiler load, deep load control, as well as control of the superheat temperature of steam in this load control range. For a more complete combustion of fuel and increased efficiency, fine grinding coal is fed into the afterburner, additional burners 6 of the upper tier are connected to its supply path.

The described stabilization is especially necessary in the application of the WUT from waste. In this case, the fluxes of VUT droplets sprayed by the nozzles of additional burners 5 of the lower tier are washed from above by the torches of the main burners and the high-temperature combustion core, and from below by the oncoming burning stream of the peripheral vortex, therefore, the droplets of the VUT are intensively dried, heated, ignited and burned. The entire flow of low-quality fuel-and-oil fuel assembly is supplied to the combustion chamber 7 through additional burners 5 of the lower tier, which are located on the front 12 and rear shields 13 in the area 14 of the pinch neck. Fuel, fuel injection pump, and coal dust illumination do not completely burn out in a small volume of the combustion chamber 7, and the torch fills the afterburner 4. The size of this torch is controlled by the supply of secondary blast through nozzles 15, and this also allows maintaining steam overheating.

In the variant of replacing expensive liquid and gaseous fuels with coal in the form of a high-quality high-calorific fuel oil, the entire stream of fuel oil is fed into the combustion chamber 7, moreover, it is supplied both through the main burners 9 and through additional burners 5 of the lower tier. Such an increased number of jets with VUT drops provides a large contact surface of the jets with the combustion medium. The combustion chamber 7 is transferred to a more stable mode of operation - in gasification mode with filling the combustion chamber 7 with a mixture of highly reactive products of incomplete combustion. These measures also make it possible to ensure sustained ignition of VUT. The main combustion of the VUT torch and the heat perception by the screens are distributed into the afterburner 4. The VUT particles are burned in the flow of the missing air entering through the nozzles 15 of the secondary blast in the region 14 of the pinch neck.

Thus, the use of the proposed swirl furnace in comparison with the prototype NTV [Kotler V.R. Special furnaces of power boilers. - M: Energoatomizdat, 1990, p. 43, fig. 22] allows:

- provide increased efficiency;

- expand the range of load regulation, while maintaining steam overheating and at low boiler load;

- involve in the fuel balance various sludges and carbon-containing waste with their supply in the form of HLW;

- to transfer gas-oil boilers from liquid and gaseous fuels to coal, including in the form of fuel-and-chemical fuel.

Claims (7)

1. A vortex furnace divided by a two-sided pinch formed by folding the screens onto an afterburner with additional burners and a combustion chamber located below it with the main burners installed with a downward inclination on the lower faces of the pinch, the combustion chamber made with a cold funnel and the main burners installed tangentially tangent to the conditional circle located in the combustion chamber, with an axis coinciding with the axis of the furnace. 2. The vortex furnace according to claim 1, characterized in that the additional burners of the lower tier are located in the area of the neck of the pinch and are connected to the feed path of the fuel-injection device, and they are installed, like the main burners, with an inclination downward and tangentially, their jets cover the jets of the main burners from below. 3. Vortex furnace according to claim 1 or 2, characterized in that in the zone of the neck of the pinch nozzles of the secondary blasting are located. 4. Vortex furnace according to claim 1 or 2, characterized in that the additional burners of the upper tier are connected to the supply path of fine coal. 5. Vortex furnace according to claim 1 or 2, characterized in that a post-combustion grate is located at the mouth of the cold funnel. 6. Vortex furnace according to claim 1 or 2, characterized in that in the right and left halves of the combustion chamber on the walls of the cold funnel are located at least one tier of the lower blast nozzle directed towards the opposite wall of the cold funnel, oriented in a coordinated plan with the direction of the burners. 7. Vortex furnace according to claim 1 or 2, characterized in that the main and additional burners of the lower tier, located in the area of the neck of the pinch, are connected to the supply path of the VUT.

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