GB2126676A - Riffle assembly - Google Patents

Abstract

A riffle assembly comprises a casing 10 having at least one inlet 14, a plurality of outlets 16, at least one riffle unit 18 between the or each inlet and the outlets, communication passages within the assembly having streamlined design. A through passage 12 for input of material to a mill may be provided. The or each riffle unit may be of the type described in U.K. Patent Specification No. 1297372. <IMAGE>

Description

SPECIFICATION Improvements in and relating to riffle assemblies for the control of moving fluids This invention relates to a riffle assembly for the control of a moving fluid, and in particular is concerned with the control of delivery of pulverised fuel from a mill to an electric power station.

According to the present invention there is provided a riffle assembly comprising a casing having at least one inlet, a plurality of outlets, and at least one riffle box unit disposed between the or each inlet and the outlets to distribute material entering the inlet evenly amongst the outlets, communication passages in the casing between the location of the or each riffle box unit and the outlets having a streamlined design for passage of material therethrough.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a riffle assembly according to the invention; and Fig. 2 is a front elevation of the assembly of Fig. 1.

Referring to the drawings, a riffle assembly comprises a casing 10 through which passes a portion of a through passageway 1 2 for feeding material such as coal, to be pulverised into a pulverising mill (not shown). The pulverised material is carried upwards by an air stream from the mill to the riffle assembly. The latter has two bottom inlets 14 each of which communicates through passages of the casing 10 with each of the outlets 16.

Between each inlet 14 and the outlets 16 is a riffle box unit 1 8 comprising a riffle box 20 and a supporting cover plate 22. The riffle box 20 incorporates a series of pockets or passages 24 all opening to the inlet, and alternate passages of which are directed towards different ones of the two outlets 1 6. The riffle boxes 20 therefore divide the incoming fuel/air mixture entering each of the inlets 1 4 evenly between the two outlets 1 6. The riffle box is preferably constructed in accordance with that described in our U.K. Patent Specification No. 1 297372 but other constructions of riffle box can also be used.

Each riffle box unit is substantially triangular in end view and is adapted for slidabie location in the casing 10 through an aperture 26. When fully in position the unit may be detachably secured to the casing 10 in any desired fashion and is then correctly located between the associated inlet 14 and the two outlets 16 but can be readily removed for repair or replacement.

To achieve as efficient a flow of material as possible, the internal passages communicating between the riffle box units 1 8 and the outlets 1 6 are streamlined to approach as near as possible to passages of tubular cross-section.

The riffle assembly is basically designed to fit directly on to a two outlet mill. When fuel passes through a pulverising mill without assembly fitted, it is impossible to obtain even distribution from the two outlets and the differential can be as much as 20%. Consequently the air/fuel ratio serving the burners is uneven, resulting in different temperature gradients and heavy carbon ingrit losses due to the poor firing conditions.

With the riffle assembly fitted, the air/fuel is subdivided to give an even flow from each outlet and consequently the above problems of poor firing conditions are rectified and stable conditions across the boiler width are maintained.

Various modifications may be made without departing from the invention. For example the riffle box units may be of any desired shape in end view adapted to fit into appropriately shaped openings in the assembly casing. Moreover there may be only one, or more than two riffle boxes.

The assembly can be used in other situations where control of fluids or suspensions is required and need not have a central through passage.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.

Claims

1. A riffle assembly comprising a casing having at least one inlet, a plurality of outlets, and at least one riffle box unit disposed between the or each inlet and the outlets to distribute material entering the inlet evenly amongst the outlets, communication passages in the casing between the location of the or each riffle box unit and the outlets having a streamlined design for passage of material therethrough.

2. A riffle assembly as claimed in claim 1, in which there is provided a passageway through the assembly, the passageway receiving material to be pulverised, said material leaving the passageway and passing to a pulverising mill associated with said assembly, pulverised material being received from said mill through the or each unit.

3. A riffle assembly as claimed in claim 1 or claim 2, in which the or each riffle box comprises a unit substantially triangular in end elevation having a plurality of side by side compartments each compartment communicating at one end with the or one of the inlets, alternate compartments communicating at their other ends with a respective one of the outlets.

4. A riffle assembly as claimed in any preceding claim, in which the or each riffle unit is releasably mounted in the assembly.

5. A riffle assembly as claimed in claim 4, in which the or each riffle unit is slidably received in the assembly.

6. A riffle assembly as claimed in claim 4, in which the or each riffle unit has an end wall which

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in and relating to riffle assemblies for the control of moving fluids This invention relates to a riffle assembly for the control of a moving fluid, and in particular is concerned with the control of delivery of pulverised fuel from a mill to an electric power station. According to the present invention there is provided a riffle assembly comprising a casing having at least one inlet, a plurality of outlets, and at least one riffle box unit disposed between the or each inlet and the outlets to distribute material entering the inlet evenly amongst the outlets, communication passages in the casing between the location of the or each riffle box unit and the outlets having a streamlined design for passage of material therethrough. An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a riffle assembly according to the invention; and Fig. 2 is a front elevation of the assembly of Fig. 1. Referring to the drawings, a riffle assembly comprises a casing 10 through which passes a portion of a through passageway 1 2 for feeding material such as coal, to be pulverised into a pulverising mill (not shown). The pulverised material is carried upwards by an air stream from the mill to the riffle assembly. The latter has two bottom inlets 14 each of which communicates through passages of the casing 10 with each of the outlets 16. Between each inlet 14 and the outlets 16 is a riffle box unit 1 8 comprising a riffle box 20 and a supporting cover plate 22. The riffle box 20 incorporates a series of pockets or passages 24 all opening to the inlet, and alternate passages of which are directed towards different ones of the two outlets 1 6. The riffle boxes 20 therefore divide the incoming fuel/air mixture entering each of the inlets 1 4 evenly between the two outlets 1 6. The riffle box is preferably constructed in accordance with that described in our U.K. Patent Specification No. 1 297372 but other constructions of riffle box can also be used. Each riffle box unit is substantially triangular in end view and is adapted for slidabie location in the casing 10 through an aperture 26. When fully in position the unit may be detachably secured to the casing 10 in any desired fashion and is then correctly located between the associated inlet 14 and the two outlets 16 but can be readily removed for repair or replacement. To achieve as efficient a flow of material as possible, the internal passages communicating between the riffle box units 1 8 and the outlets 1 6 are streamlined to approach as near as possible to passages of tubular cross-section. The riffle assembly is basically designed to fit directly on to a two outlet mill. When fuel passes through a pulverising mill without assembly fitted, it is impossible to obtain even distribution from the two outlets and the differential can be as much as 20%. Consequently the air/fuel ratio serving the burners is uneven, resulting in different temperature gradients and heavy carbon ingrit losses due to the poor firing conditions. With the riffle assembly fitted, the air/fuel is subdivided to give an even flow from each outlet and consequently the above problems of poor firing conditions are rectified and stable conditions across the boiler width are maintained. Various modifications may be made without departing from the invention. For example the riffle box units may be of any desired shape in end view adapted to fit into appropriately shaped openings in the assembly casing. Moreover there may be only one, or more than two riffle boxes. The assembly can be used in other situations where control of fluids or suspensions is required and need not have a central through passage. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon. Claims

1. A riffle assembly comprising a casing having at least one inlet, a plurality of outlets, and at least one riffle box unit disposed between the or each inlet and the outlets to distribute material entering the inlet evenly amongst the outlets, communication passages in the casing between the location of the or each riffle box unit and the outlets having a streamlined design for passage of material therethrough.

2. A riffle assembly as claimed in claim 1, in which there is provided a passageway through the assembly, the passageway receiving material to be pulverised, said material leaving the passageway and passing to a pulverising mill associated with said assembly, pulverised material being received from said mill through the or each unit.

3. A riffle assembly as claimed in claim 1 or claim 2, in which the or each riffle box comprises a unit substantially triangular in end elevation having a plurality of side by side compartments each compartment communicating at one end with the or one of the inlets, alternate compartments communicating at their other ends with a respective one of the outlets.

4. A riffle assembly as claimed in any preceding claim, in which the or each riffle unit is releasably mounted in the assembly.

5. A riffle assembly as claimed in claim 4, in which the or each riffle unit is slidably received in the assembly.

6. A riffle assembly as claimed in claim 4, in which the or each riffle unit has an end wall which when the unit is received within the assembly forms part of the casing.

7. A riffle assembly substantially as hereinbefore described with reference to the accompanying drawings.