PL239165B1 - Method and flow installation for spraying suspensions, in particular fuel suspensions, in burners - Google Patents

Description

Description of the invention

The subject of the invention is a method and a flow-through installation for spraying suspensions, especially fuel ones, in burners.

The condition for good combustion of liquid fuels is their good mixing with the oxidant (air or oxygen), heating and initialization, which is carried out in the burner.

Atmospheric (injector) burner is a type of burner in which the gaseous fuel flowing from the nozzle sucks in the oxidant around the nozzle, with which it mixes and forms a flammable mixture: in the case of liquid fuels, the process of mixing with the oxidant is preceded by the evaporation of the fuel. A blow (pressure / fan) burner is a type of burner in which the flow of the oxidant necessary to burn liquid fuel is forced through the initial pressure of the oxidant. In burners, this type of liquid fuel flowing from the nozzle is mixed with the oxidant flowing around it (obliquely or swirling). There are also known burners for the combustion of quasi-liquid fuels (coal dust) fed with the dust-air mixture produced in coal mills in the vortex and jet variants. There are also dual-fuel burner solutions in which, in the axis of a pulverized pulverized burner, there is a liquid fuel burner lance, from which the outgoing fuel stream is dispersed with the added stream of steam into a fine-droplet form prior to mixing with the oxidant.

A device for forming streams of a dust-air mixture is known from the patent application P.384187. in which the following are installed coaxially around the dust-air mixture duct: the cooling-separating air duct, the secondary air duct and the gas combustion air duct with gas lances installed at its outlet, around the burner, inside the duct with gas lances. However, for economic reasons, the continuous operation of the pulverized lance burner set is generally not used, and liquid or gaseous fuel is only burned exceptionally, most often during boiler start-up. In this situation, the lance burner is not used as part of a combustion system with low nitrogen oxide emissions.

Moreover, they are known from the literature (Manfred RK, Borio RW, Smith D. A, Rini MJ, LaFlesh RC, Marion JL: Current Progress in Coal-Water Slurry Burner Development. American Chemical Society Symposium March 20-25. 1983, Seattle, Washington) burners for the combustion of hydrocarbon suspension / suspension, where the suspension lance is placed in the axis of the burner, and there is an annular air duct with swirl blades concentrically around it. Burners operating on the same principle are described in the literature (Prakash Ramachandran. Ching-Yi Tsai. Gary W. Schanche: An Evaluation of Coal Water Slurry Fuel. Burners and Technology, USACERL Technical Report FE-93/09 November 1992).

It was unexpectedly found that when, in place of the low-temperature suspension, a high-pressure suspension of ground solid fuel is used, heated to a temperature slightly below the saturation parameters, explosive dispersion of fuel particles with wet vapor of the suspension carrier will occur as a result of expansion of the suspension in the nozzle, preceded by one or multi-stage mixing with the oxidant in the subsequent torch parts.

The method of spraying the suspension according to the invention consists in the fact that the suspension of particulate solid fuel in a liquid flows under high pressure to the burner in the furnace, which is heated in the suspension heater to a temperature close to the liquid saturation temperature and expands in the suspension nozzle in the burner to the pressure in the furnace. , and the saturated steam generated during expansion disperses fuel particles that form a suspension of solid fuel particles in a wet liquid vapor, while the suspension of fuel particles in wet vapor after single or multi-stage mixing with hot gas with an oxidant in concentric nozzles of the burner forms a combustible mixture, and after mixing with hot gas without oxidant in concentric nozzles creates conditions for drying the mixture.

The flow system for spraying the suspension is characterized by the fact that the tank for collecting the fuel suspension is connected by a pipeline with a high-pressure suspension pump, then with a suspension heater and suspension nozzle, which is equipped with a throttling suspension expansion unit consisting of a suspension nozzle and a valve plug with a driving actuator, and downstream of the nozzle for spraying the suspension, concentric nozzles of the multi-stage hot gas mixer with oxidant are installed, connected by a window to the furnace and a duct to the heater, and then to a duct preferably to a continuous flow machine.

The solution according to the invention allows direct combustion in the boiler burners of fuel suspensions such as flotation concentrate or coal sludge from sedimentation ponds without preliminary preparation.

This means that no costly grinding process is required and also no pre-drying. The burner according to the invention may be grouped into assemblies enabling the primary NOx reduction method based on air and fuel staging by selecting different combustion stoichiometry.

A flow-through plant for spraying the suspension can also be used as a premix with the hot drying gases in dryers.

The subject of the invention is illustrated in the embodiment in the drawing, which shows a diagram of the installation explaining the method of spraying suspensions, especially fuel suspensions, in the burners.

A suspension of crushed solid fuel in a liquid flows under high pressure to the burner 10 in the furnace, which is heated in the suspension heater 3 to a temperature close to the liquid saturation temperature and is expanded in the suspension nozzle 7 in the burner 10 to the pressure in the furnace, and the steam generated during expansion is saturated disperses fuel particles that form a suspension of solid fuel particles in a vapor of a wet liquid, while the suspension of fuel particles in wet vapor after one or more stages of mixing with hot gas with an oxidant in concentric nozzles 8, 9 of the burner 10 creates a combustible mixture burned in the burner 10 and after mixing with hot gas without oxidant in concentric nozzles 8, 9 it creates conditions for drying the mixture.

Water and / or oils and / or other flammable liquids are used to prepare a suspension of the comminuted solid fuel, and the comminuted solid fuel in the suspension is a flotoconcentrate, coal sludge or biomass with particle size R0.09 <50%.

The flow installation is equipped with a throttling suspension expansion unit consisting of a spray nozzle 7 and a valve plug 6 with a driving actuator 5, which generates a suspension of fuel particles in wet vapor. Downstream of the suspension spraying nozzle 7, there are concentric nozzles 8 and 9 of the multi-stage mixer connected by the window 11-2 to the furnace and the channel 11-1 to the heater 12, and then to the channel 13 preferably to the flow machine 14 inducing the gas flow with the oxidant for combustion in the burner 10, also preferably with a continuous flow machine 14 inducing a gas flow without oxidant in the suspension drying plant.

Claims (2)

Patent claims Method of spraying suspensions, especially fuel ones, in burners, characterized in that a suspension of particulate solid fuel in a liquid flows under high pressure to the burner 10 in the furnace, which is heated in the suspension heater 3 to a temperature close to the liquid saturation temperature and expands in the suspension nozzle 7 in the burner 10 to the pressure in the furnace, and the saturated steam generated during the expansion disperses fuel particles that form a suspension of solid fuel particles in a wet liquid vapor, the suspension of fuel particles in wet vapor after one or more stages mixing with the hot gas with the oxidant in concentric nozzles 8, 9 of burner 10 creates a combustible mixture and after mixing with hot gas without oxidant in concentric nozzles 8, 9 creates conditions for drying the mixture. 2. Flow system for spraying suspensions, especially fuel ones, in burners, characterized in that the tank 1 for collecting the fuel suspension is connected by a pipeline 4 with a high-pressure suspension pump 2, then with a suspension heater 3 and a suspension nozzle 7, which is equipped with a throttling suspension expansion unit consisting of a suspension nozzle 7 and a valve plug 6 with a drive actuator 5, and behind the suspension nozzle 7, concentric nozzles 8 and 9 of a multi-stage hot gas mixer with an oxidizer are installed, connected by a window 11-2 with a furnace and a duct 11-1 with a heater 12 a then through channel 13 preferably with a continuous machine 14.