RU2419050C1 - Heat generator operating on straw - Google Patents

Abstract

FIELD: power engineering. ^ SUBSTANCE: heat generator comprises a gasification chamber locked with a door, equipped with air ducts having nozzles to supply primary air and an afterburning chamber comprises nozzles for secondary air supply. Primary air ducts are arranged at the distance from the gasification chamber sole, the space under pipes serves to collect ashes. The afterburning chamber is arranged vertically inside the gasification chamber, gas inlet into the afterburning chamber happens via an open lower end of the afterburning chamber in the lower part of the gasification chamber. The afterburning chamber outlet is equipped with channels with a device for supply (recirculation) of some smoke gases into air ducts of the primary air. ^ EFFECT: heat generator design makes it possible to reduce ash content in smoke gases, to improve quality of gas afterburning, application of hot smoke gases recirculation makes it possible to improve heat generator capacity and to burn straw of high moisture. ^ 2 cl, 2 dwg

Description

The invention relates to heat engineering, in particular to heat generators operating on renewable biofuel, mainly on straw in cylindrical rolls, designed to produce hot flue gases, and can be used in grain drying complexes for drying grain, for heating livestock farms, industrial and residential buildings etc.

A heat generator is known (RF patent No. 2263852, IPC F24H 1/44, dated April 16, 2004) containing a firebox closed by a door serving as a gasification chamber. In the lower part of the furnace there is a grate, on which a straw roll is placed. In the upper part of the furnace there is a post-combustion chamber located at the entrance to the heat exchange unit. The afterburner is equipped with a secondary air supply device.

The burning of straw in such a heat generator cannot occur efficiently, since during burning each straw is covered with a layer of ash, which prevents the access of atmospheric oxygen to the unburned part of the straw. Despite the uniform distribution of air, the grate cannot, due to the low velocity of the air, allow the ash to be blown off from the straws, which reduces the burning rate and reduces the heat output of the heat generator. With lower combustion of fuel and the upper location of the afterburner, the gas passes through a layer of straw that varies in thickness as the roll burns out, because of which its composition is constantly changing, which leads to unstable thermal power of the heat generator.

A heat generator (patent EP 1695009 B1, IPC F23G 7/06, dated January 14, 2009) of a gas-generating type for straw bales is also known.

The heat generator comprises a gasification chamber, which is also a loading chamber, in which a straw roll is placed, and a nozzle is located in the lower part of the gasification chamber, through which gas enters the downstream combustion chamber. On both sides of the nozzle in the gasification chamber are recesses in which ash is collected. To remove ash from straws, a blower fan is installed on the gasification chamber. Final flue gas cleaning is carried out in an inertial cleaner.

The disadvantage of this technical solution is that in a downward flow of gas, the gas contains a significant amount of fly ash, an inertial cleaner is used to clean it, which complicates the design. Also, because of the afterburner, located under the gasification chamber, the heat generator has bulky dimensions.

The closest in technical essence to the proposed invention is a heat generator (Installation and Operating Instructions for FARM 2000 Boilers, p.17 (Installation and Operating Instructions for FARM 2000 Boilers, http://www.farm2000.co.uk/docs/Installation.pdf )) gas-generating type for biofuel, incl. and for straw rolls.

The heat generator comprises a gasification chamber closed by a door, which is at the same time a loading chamber in which a straw roll is placed. At the bottom of the gasification chamber there is an air duct with nozzles through which primary air enters for the gasification of straw. At the entrance to the heat exchange unit located on the roof of the gasification chamber, there is a afterburning zone into which secondary air enters through the air duct with nozzles.

The burning of a straw roll is as follows. A roll of straw is laid in the gasification chamber, which is gasified by supplying primary air, the resulting gas burns out in the afterburning zone, where secondary air is supplied through the nozzles.

The design of the known heat generator cannot be considered technically perfect. The nozzles for supplying primary air are located close to the bottom of the gasification chamber, where ash is collected from burning straw, the ash rises by jets of primary air, as a result of which flue gases are polluted. The location of the primary air duct on the hearth reduces the amount of space in which the ash accumulates, this requires frequent cleaning of the ash chamber of the gasification. The afterburning of gas occurs in the afterburning zone, which opens on three sides to the gasification chamber, such a technical solution does not exclude the possibility of getting unburned gas into the heat exchange unit.

The objective of the present invention is to increase the intensity of combustion of straw in order to increase the thermal power of the heat generator, the quality of gas afterburning, reduce the content of fly ash in flue gases and the possibility of burning straw with high humidity.

The problem is achieved in that the heat generator, which runs on straw mainly in cylindrical rolls, contains a gasification chamber closed by the door, in the lower part of the gasification chamber are installed primary air ducts (air supply pipes) containing nozzles, an afterburner with nozzles for feeding secondary air is installed vertically in the gasification chamber, while the gas enters the afterburner in the lower part of the gasification chamber through the open lower end EASURES afterburning, on the arch upper part of the gasification chamber afterburner interfaced with the flue pipe.

The task is also achieved by the fact that the output of the afterburner (the upper part of the afterburner) is equipped with channels with a device for feeding (recirculating) part of the flue gases into the primary air ducts.

The claimed technical solution is illustrated by drawings, where figure 1 shows a General view of the device; figure 2 is a section aa.

The straw heat generator comprises a gasification chamber 1 with a door 2. At the bottom of the gasification chamber are air supply pipes 3 with primary air supply nozzles 4. Air supply pipes 3 are located at a distance from the bottom of the gasification chamber 1. A straw 5 roll is placed on the air supply pipes 3 A vertically mounted afterburning chamber 6 with secondary air nozzles 7 is located in the gasification chamber 1. The open lower end of the afterburning chamber 6 is located in the lower part of the gasification chamber 1, inner the surface of the afterburning chamber can be lined with a heat-insulating material to increase its life 8. The afterburning chamber 6, with its upper part on the roof of the gasification chamber 1, is connected to the gas duct 9. The upper part of the afterburning chamber 6 is connected by channels 10 equipped with recirculation devices 11, for example, ejectors, with air supply pipes 3. At the bottom of the gasification chamber 1 is a door 12 and / or a screw (screw) conveyor 13 for removing ash. The heat generator operates as follows. In the gasification chamber 1, through the door 2, a straw 5 roll is installed on the air supply pipes 3. The straw is ignited from the burning residues of the previous roll or during the initial kindling from specially laid and ignited biomass. The air necessary for gasification is supplied through the air supply pipes 3 and through nozzles 4 it enters the straw roll 5. The gas generated during the gasification of straw enters the afterburner 6 through the open bottom end, secondary air is supplied through the nozzles 7. Flue gases enter the gas duct 9. Since the lower end of the afterburner 6, through which the gas enters, is located in the lower part of the gasification chamber 1, the flow of air and gasification products has a mainly horizontal direction, which leads to the combustion of straw in horizontal layers and, as a result, stabilization of the calorific value of the gas as the straw roll burns out. The gas at the entrance to the gasification chamber 6 changes the direction of the flow from horizontal to vertical upward, due to which there is an inertial purification of gas from volatile ash particles. The ash generated during the combustion of a roll of straw 5, and also falling out under the inlet of the afterburner 6, is collected in the lower part of the gasification chamber 1 under the air supply pipes 3. The air supply pipes 3 are located at a distance from the bottom of the gasification chamber 1 to reduce the rise of ash with primary air jets and for the convenience of cleaning the gasification chamber 1 from ash. Ash is periodically removed manually through the door 12 or mechanically by a screw conveyor 13. Due to the high content of alkali metal salts, straw ash has a low melting point of 900-950 ° C. To reduce the temperature of combustion and prevent melting of the ash, part of the flue gas is recirculated through channels 10 by recirculation devices 11 into the primary air. Lowering the combustion temperature allows you to supply additional air and thereby increase the capacity of the heat generator. On the other hand, recirculating flue gases add additional heat to the gasification chamber, which contributes to better gasification of straw with high humidity. This also contributes to the heat radiated from the outer surface of the afterburner 6.

For grain drying, flue gases leaving the heat generator through a gas duct 9 at a high temperature then enter the mixing chamber, where they are ballasted with air to the temperature necessary for drying the grain, or to the heat exchanger, where the heat carrier is supplied to heat buildings and premises.

Thus, the vertical placement of the afterburning chamber 6 in the gasification chamber 1 and the location of the primary air supply pipes 3 at a distance from the bottom of the gasification chamber 1 allows to reduce the ash content in the flue gases, providing a gas inlet through the open lower end of the afterburning chamber ensures high-quality interaction with the secondary air jets and improves the quality of gas afterburning, the use of channels 10 with recirculation devices 11 flue gases can increase the power of the heat generator and burn straw with high humidity.

Claims (2)

1. A heat generator operating on straw mainly in cylindrical rolls, comprising a gasification chamber closed by a door, equipped with air ducts with nozzles for supplying primary air, and an afterburner containing nozzles for supplying secondary air, characterized in that the primary air ducts are located at a distance from hearth of the gasification chamber, the afterburner is located vertically inside the gasification chamber, the lower end of the afterburner, open for gas inlet, is located at the bottom of the chamber ry gasification. 2. The heat generator according to claim 1, characterized in that the output of the afterburner is equipped with channels with devices for supplying part of the flue gases to the primary air ducts.

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