GB2091414A

GB2091414A - Solid fuel combustion appliances

Info

Publication number: GB2091414A
Application number: GB8039086A
Authority: GB
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1980-12-05
Filing date: 1980-12-05
Publication date: 1982-07-28

Abstract

A solid fuel combustion appliance includes a primary combustion zone (6) for burning solid fuel in a firebed (50) from which exhaust gases issue into a secondary combustion zone (30). The zone (30) has a chamber (38) of greater cross-sectional area than the inlet (39) or the outlet (40) thereof. <IMAGE>

Description

SPECIFICATION Improvements in or relating to solid fuel combustion appliances This invention concerns improvements in or relating to solid fuel combustion appliances.

An object of the invention is provide a solid fuel combustion appliance with an enhanced capability of reducing smoke emission.

Accordingly the invention provides a solid fuel combustion appliance including a body incorporating a grate for supporting a fire bed in a primary combustion zone, a fuel feed access to the primary combustion zone, a primary air inlet in the body, an exhaust gas outlet from the body, and a secondary combustion zone located upstream of the exhaust gas outlet for receiving exhaust products of combustion from the primary combustion zone, the secondary combustion zone having an inlet and an outlet leading to and from a chamber the cross-sectional area of which is greater than the cross-sectional area of the inlet or the outlet thereto.

The appliance may conveniently be provided with waterways which constitute a boiler of single or double pass configuration.

The appliance may, however, be in the form of a stove or warm air unit in which case, waterways may be not be provided.

A secondary air inlet arrangement may advantageously be provided and may be located adjacent the inlet to the secondary combustion zone.

The secondary combustion zone comprises the chamber and the inlet and outlet thereto all of which may be formed of refractory material either of unitary construction or of one or more parts registering one with the other. The appliance preferably operates on a down-draught principle whereby primary combustion air is drawn down through the fire bed, the exhaust products of combustion leaving the fire bed at the base thereof. The secondary combustion zone is conveniently disposed adjacent the base of the fire bed with one wall of the chamber constituting a boundary of the bed. The secondary air inlet arrangement may be formed in the lower part of that boundary wall and includes one or more outlets directed towards the inlet to the secondary combustion zone.

By way of example only one embodiment of a solid fuel combustion appliance according to the invention is described below with reference to the accompanying drawing which is a sectional side view.

Referring to the drawing, a solid fuel combustion appliance 1 includes a body 2 enclosing a grate 4 provided with a riddling device (not shown). An ash receiving area 5 is located beneath the grate 4. A primary combustion zone 6 is defined within the body 2 between the front 8 thereof which incorporates a fuel feed access door 10, and at the relatively upper part of the zone, a waterway 1 2. Further waterways 14 to the rear of 12 define flue passages 1 6 which lead to a main flue 18.

A primary combustion air inlet 20 is provided in the front 8 as is a water thermostat 22 which is operable to vary the opening of the inlet 20 by means of a plate 24. A bypass 26 is located adjacent the top of the body 2 and the top of the waterway 12.

A secondary combustion zone 30 is situated adjacent the top of the grate 4 and at the base of the rear of the primary combustion zone 6. The zone 30 is defined by one or more refractory members and has a front wall 34 forming the lower rear boundary of the primary combustion zone 6, and a rear wall 36, a chamber 38 being disposed between the walls 34, 36. The walis 34, 36 extend between the sides (not shown) of the body 2 of the appliance 1 and form at the lower and upper edges, an inlet 39 and an outlet 40 respectively. The chamber 38 is of greater crosssection than either the inlet 39 or the outlet 40.

The front wall 34 has formed in its lower region a passageway 42 to which is connected a conduit 44 for the supply of secondary combustion air which in use issues from apertures 46 provided in the wall 34, the apertures being directed towards the inlet 39.

In use, solid fuel, coal, is fed to the appliance 1 to form a fire'bed 50 in the primary combustion zone 6 and after ignition, primary combustion air is drawn through the inlet 20 down into the bed 5 to promote combustion, the exhaust products of combustion leaving at the base of the fire bed 50 to pass to the flue passages 1 6. However, these products which include volatiles emitted during combustion, first enter the secondary combustion zone 30 through the inlet 39. At this point secondary combustion air is added via the apertures 46 and the mixture of air and combustion products enters the chamber 38. In the chamber 38, the products from primary combustion undergo secondary combustion in order to burn the volatiles prior to exhaust emission to the atmosphere through the main flue 18.Since both the inlet 39 and the outlet 40 are of smaller cross-sectional area than the chamber 38, a constriction is imposed upon gas flow and the shape of the chamber 38 which tends to be curvilinear, result in a swirling effect being given to the mixture of secondary air and combustion products thus affording a greater residence time and improved mixing than would otherwise be the case. The volatiles can therefore be burnt off more effectively thus giving an enhanced smoke reduction.

The products of the secondary combustion issue through the outlet 40 from zone 30 and thence pass through the flue passages 1 6 giving up heat to the water in the waterways 12, 14 before their final egress through the main flue 1 8.

1. A solid fuel combustion appliance including a body incorporating a grate for supporting a fire bed in a primary combustion zone, a fuel feed access to the primary combustion zone, a primary

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to solid fuel combustion appliances This invention concerns improvements in or relating to solid fuel combustion appliances. An object of the invention is provide a solid fuel combustion appliance with an enhanced capability of reducing smoke emission. Accordingly the invention provides a solid fuel combustion appliance including a body incorporating a grate for supporting a fire bed in a primary combustion zone, a fuel feed access to the primary combustion zone, a primary air inlet in the body, an exhaust gas outlet from the body, and a secondary combustion zone located upstream of the exhaust gas outlet for receiving exhaust products of combustion from the primary combustion zone, the secondary combustion zone having an inlet and an outlet leading to and from a chamber the cross-sectional area of which is greater than the cross-sectional area of the inlet or the outlet thereto. The appliance may conveniently be provided with waterways which constitute a boiler of single or double pass configuration. The appliance may, however, be in the form of a stove or warm air unit in which case, waterways may be not be provided. A secondary air inlet arrangement may advantageously be provided and may be located adjacent the inlet to the secondary combustion zone. The secondary combustion zone comprises the chamber and the inlet and outlet thereto all of which may be formed of refractory material either of unitary construction or of one or more parts registering one with the other. The appliance preferably operates on a down-draught principle whereby primary combustion air is drawn down through the fire bed, the exhaust products of combustion leaving the fire bed at the base thereof. The secondary combustion zone is conveniently disposed adjacent the base of the fire bed with one wall of the chamber constituting a boundary of the bed. The secondary air inlet arrangement may be formed in the lower part of that boundary wall and includes one or more outlets directed towards the inlet to the secondary combustion zone. By way of example only one embodiment of a solid fuel combustion appliance according to the invention is described below with reference to the accompanying drawing which is a sectional side view. Referring to the drawing, a solid fuel combustion appliance 1 includes a body 2 enclosing a grate 4 provided with a riddling device (not shown). An ash receiving area 5 is located beneath the grate 4. A primary combustion zone 6 is defined within the body 2 between the front 8 thereof which incorporates a fuel feed access door 10, and at the relatively upper part of the zone, a waterway 1 2. Further waterways 14 to the rear of 12 define flue passages 1 6 which lead to a main flue 18. A primary combustion air inlet 20 is provided in the front 8 as is a water thermostat 22 which is operable to vary the opening of the inlet 20 by means of a plate 24. A bypass 26 is located adjacent the top of the body 2 and the top of the waterway 12. A secondary combustion zone 30 is situated adjacent the top of the grate 4 and at the base of the rear of the primary combustion zone 6. The zone 30 is defined by one or more refractory members and has a front wall 34 forming the lower rear boundary of the primary combustion zone 6, and a rear wall 36, a chamber 38 being disposed between the walls 34, 36. The walis 34, 36 extend between the sides (not shown) of the body 2 of the appliance 1 and form at the lower and upper edges, an inlet 39 and an outlet 40 respectively. The chamber 38 is of greater crosssection than either the inlet 39 or the outlet 40. The front wall 34 has formed in its lower region a passageway 42 to which is connected a conduit 44 for the supply of secondary combustion air which in use issues from apertures 46 provided in the wall 34, the apertures being directed towards the inlet 39. In use, solid fuel, coal, is fed to the appliance 1 to form a fire'bed 50 in the primary combustion zone 6 and after ignition, primary combustion air is drawn through the inlet 20 down into the bed 5 to promote combustion, the exhaust products of combustion leaving at the base of the fire bed 50 to pass to the flue passages 1 6. However, these products which include volatiles emitted during combustion, first enter the secondary combustion zone 30 through the inlet 39. At this point secondary combustion air is added via the apertures 46 and the mixture of air and combustion products enters the chamber 38. In the chamber 38, the products from primary combustion undergo secondary combustion in order to burn the volatiles prior to exhaust emission to the atmosphere through the main flue 18.Since both the inlet 39 and the outlet 40 are of smaller cross-sectional area than the chamber 38, a constriction is imposed upon gas flow and the shape of the chamber 38 which tends to be curvilinear, result in a swirling effect being given to the mixture of secondary air and combustion products thus affording a greater residence time and improved mixing than would otherwise be the case. The volatiles can therefore be burnt off more effectively thus giving an enhanced smoke reduction. The products of the secondary combustion issue through the outlet 40 from zone 30 and thence pass through the flue passages 1 6 giving up heat to the water in the waterways 12, 14 before their final egress through the main flue 1 8. CLAIMS

1. A solid fuel combustion appliance including a body incorporating a grate for supporting a fire bed in a primary combustion zone, a fuel feed access to the primary combustion zone, a primary air inlet in the body, an exhaust gas outlet from the body, and a secondary combustion zone located upstream of the exhaust gas outlet for receiving exhaust products of combustion from the primary combustion zone, the secondary combustion zone having an inlet and an outlet leading to and from a chamber the cross-sectional area of which is greater than the cross-sectional area of the inlet or the outlet thereto.

2. The appliance according to claim 1 in which a secondary air arrangement is provided adjacent to the inlet to the secondary combustion zone.

3. An appliance according to claim 1 or 2 in which the chamber of the secondary combustion zone is formed of refractory material.

4. An appliance according to claim 3 in which the refractory material forming the chamber is of unitary construction.

5. An appliance according to claim 3 in which the refractory material forming the chamber is made of one or more parts.

6. A solid fuel combustion appliance substantially as hereinbefore described with reference to the accompanying drawing.