RU2343349C1 - Pulverised-coal burner with aerodynamic converter of air-and-coal mixture flow - Google Patents

Abstract

FIELD: heating systems.

SUBSTANCE: invention refers to heat engineering and can be used as a pulverised-coal burner for the boilers of thermal power stations and industrial boiler houses. This is ensured by the fact that the aerodynamic converter installed in an annular duct meant for supplying air-and-coal mixture after the swirler in the direction of air-and-coal mixture is made in the form of at least three longitudinal radial partitions uniformly located in a circumferential direction of annular duct, and parallel once-through ducts forming a system.

EFFECT: simplifying the design, increasing fuel ignition velocity and efficiency of fuel combustion during two-stage pulverised coal combustion at maintaining the reduced output of fuel nitrogen oxides.

3 cl, 2 dwg

Description

The invention relates to a power system and can be used as a pulverized coal burner for boilers of thermal power plants and industrial boiler rooms.

Known is taken as the closest analogue of the invention to a vortex dust-coal burner containing a central channel for accommodating an ignition device, consecutively arranged annular channels for supplying air mixture and secondary air with blade swirls in each channel and installed in the channel for supplying air mixture behind the swirl along the air mixture aerodynamic flow transducer [1]. The aerodynamic transducer according to [1] is made in the form of a confuser-cylindrical insert and a confuser-diffuser nozzle that are installed sequentially along the flow stream, which makes it possible to reduce the formation of fuel nitrogen oxides as a result of the optimal distribution of the air mixture components over the cross section of the annular jet at the outlet of the burner. The disadvantages of the burner [1] include the structural complexity of the technical solution, as well as the deteriorated conditions for the implementation of the first stage (with a lack of oxygen) of the two-stage process of burning coal dust, resulting from the displacement by the central concentrated dust stream of high-temperature paraxial recirculation gases moving towards it.

The achieved result of the invention is to simplify the design, increase the ignition rate and completeness of fuel combustion during the two-stage combustion of coal dust while maintaining a reduced yield of fuel nitrogen oxides.

This is ensured by the fact that in a vortex pulverized coal burner containing a central channel for accommodating a kindling device, annular channels for supplying air mixture and secondary air with blade swirlers in each channel and installed in the channel for supplying the air mixture behind the swirl through aerosol mixture aerodynamic flow transducer, aerodynamic transducer according to the invention is made in the form of at least three longitudinal radial partition walls evenly spaced around the circumference of the annular channel and forming a system of direct-flow parallel channels.

Moreover, the recommended optimal number of partitions is 4 ÷ 8, and the optimal length of each partition is 1.5 ÷ 2.5 D, where D is the larger of the two inner diameters of the annular channel.

Figure 1 shows a pulverized coal burner according to the invention in longitudinal section; figure 2 is a view along arrow In figure 1.

The burner contains a central channel 1 for accommodating a kindling device, which in this particular case is a fuel oil nozzle 2 with a pipe 3 for supplying part of the air to the channel (central air). Around the central channel 1, an annular channel 4 for supplying air mixtures and two annular channels 5 and 6 for supplying secondary air are concentrically arranged coaxially with it. Channels 4, 5, 6 are equipped with inlet nozzles 7, 8, 9. In each channel 1, 4, 5, 6, blade swirls are installed, respectively, 10, 11, 12, 13 (Fig. 1). In this case, the swirlers in all channels except channel 4 for supplying air mixtures are installed at their output sections, and the swirler 11 in channel 4 is installed at the input section of this channel. An aerodynamic flow transducer is installed behind the swirler 11 at the output section of the channel 4 for supplying the air mixture; in this example, it is made in the form of six longitudinal radial baffles 14 uniformly spaced around the circumference of the annular channel 4 and forming a system of direct-flow parallel channels 15 (Fig. 2) for the release of jets 16 dust flow. The length L of each partition (Fig. 1) is 1.5 ÷ 2.5 D, where D is the larger of the two inner diameters of the annular channel 4. Each partition 14 can be made concave from the side of the incident swirling flow of the mixture. The burner is installed in the embrasure of the wall 17 of the combustion chamber.

Vortex pulverized coal burner according to the invention operates as follows. First, fuel and air are supplied to a kindling device (oil burner 1) and pipe 3 of the central channel 1, respectively. Then, air mixture and secondary air are supplied through the supply pipes 7,8,9, respectively. All flows of air and air mixtures during forward movement along the corresponding channels are vortexed using scapular swirlers 10, 11, 12, 13. The swirling flow of air mixture in the outlet part of the channel 4 runs onto the radial partitions 14 (aerodynamic flow transducer). On each partition 14, when meeting with the oncoming flow of a swirling air mixture, a stream of air-depleted coal dust is concentrated. In the furnace space, these flows move rectilinearly and fall into the axial zone of recirculation of combustion products with a low oxygen content. At the same time, on the one hand, due to the direct-flow nature of the movement of dust jets, centrifugal forces do not discard coal particles to the inner surface of the secondary air flow, where oxygen is usually intensively mixed with flammable volatile fuels. This ensures a reduced yield of fuel nitrogen oxides. On the other hand, compared with [1], the burner according to the invention, due to the separation of a continuous stream of concentrated dust into separate jets with structural simplicity, provides more favorable conditions for the efficient flow of the first stage of a two-stage fuel combustion process.

Information sources

1. Patent RU No. 2053442, 7 F 23 D 1/06, 1992.

Claims (3)

1. Vortex pulverized coal burner containing a central channel for accommodating the kindling device, successively arranged annular channels for supplying the air mixture and secondary air with blade swirls in each channel around the central channel, and an aerodynamic transducer installed in the channel for supplying the air mixture behind the swirler along the air mixture flow, characterized in that the aerodynamic transducer is made in the form of at least three longitudinal radial partitions, uniformly aspolozhennyh circumference of the annular channel and forming parallel channels ramjet system. 2. Vortex pulverized coal burner according to claim 1, characterized in that the number of partitions is 4-8. 3. Vortex pulverized coal burner according to claim 1 or 2, characterized in that the length of each partition is 1.5-2.5 D, where D is the larger of the two inner diameters of the annular channel.

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