GB2165514A

GB2165514A - Improvements in or relating to pneumatic feeder systems

Info

Publication number: GB2165514A
Application number: GB08426130A
Authority: GB
Inventors: Thomas Ronald Leigh; Andrew John Robertson
Original assignee: STURTEVANT ENG CO Ltd; Coal Industry Patents Ltd
Current assignee: STURTEVANT ENG CO Ltd; Coal Industry Patents Ltd
Priority date: 1984-10-16
Filing date: 1984-10-16
Publication date: 1986-04-16
Also published as: JPS6196320A; GB8426130D0

Abstract

A pneumatic feeder system 1 includes a pressure vessel 2 coupled to a metering pipe 18 having a first valve 14 at its entry and a second valve 22 at its exit, the second valve being perforated at 26 to provide a vent. The volumetric capacity of the pipe 18 determines the quantity of material to be fed in slug form through a conveying pipe to the point of use, an air knife or injector 16 being provided to propel the charge of material from the metering pipe 18 along the conveying pipe. <IMAGE>

Description

SPECIFICATION Improvements in or relating to pneumatic feeder systems This invention concerns improvements in or relating to pneumatic feeder systems.

In particular, the invention has reference to such systems used for the conveyance and delivery of discrete materials, for example particulate coal, in metered quantities.

In combustion equipment, it is highly desirable to be able to introduce fuel at a predetermined measured rate for control purposes to ensure that combustion proceeds with the appropriate intensity in relation to the heat output required. This requirement is especially important for boilers and more particularly so for those employing fluidised bed combustion which is sensitive to variations in fuel feed input rates.

Pneumatic feeder systems are known and generally include a pressure vessel into which the material is introduced through a valved inlet. Valving is arranged in a conveying pipe downstream of the vessel which in use is pressurised to provide the impetus for conveying the material then the valve is open. In some systems, a further air injection is provided in the conveying pipe. Systems of the known type are perfectly adequate when the delivered quantity of material is neither important nor critical. However, in operational circumstances where the material quantity is important, for example in the applications indicated above, the conventional feeder systems are inadequate.

An object of the invention is to provide an improved pneumatic feeder system which enables accurate quantities of material to be conveyed and delivered to a user location.

According to the invention a pneumatic feeder system includes a pressure vessel, an inlet to the vessel, a valve associated with the inlet, an outlet from the vessel, a metering pipe coupled to the outlet, a first valve associated with the metering pipe at the entry thereto, a second valve downstream of the first valve at the exit from the metering pipe, and a vent arranged in the second valve.

Preferably the first and second valves are ball valves spaced apart a distance determined by the length of the metering pipe, the dimensions of which define the quantity of material to be discharged by the system incrementally.

The vent in the second valve is conveniently formed by perforations in the ball.

An air injector is advantageously provided in the metering pipe intermediate the first and second valves, preferably adjacent and downstream of the first valve.

Means are provided for pressurising the pressure vessel such as in use to impel a charge of material into the metering pipe, the first valve being open.

The pressure vessel is preferably orientated with its axis vertical, the metering pipe extending either coaxially vertical therewith, or disposed horizontally, an appropriate elbow connection being provided between the outlet of the pressure vessel and the metering pipe.

By way of example only, one form of pneumatic feeder system is described with reference to the accompanying drawing which is a general arrangement of the system.

Referring to the drawing, a pneumatic feeder system shown generally at 1 includes a pressure vessel 2 of inverted hollow frusto - conical form having a domed cap 4 incorporating an inlet 6 with which is associated a solenoid controlled pneumatic charging valve 8. The pressure vessel 2 has a flanged outlet 10 coupled via an elbow joint 12 to a solenoid controlled pneumatically operable ball valve 14 adjacent to which and downstream thereof is an air injector 16.

A metering pipe 18 of predetermined length is coupled to the injector 16 and has located at its exit 20 a second solenoid controlled pneumatically operable ball valve 22, the ball 24 of which is perforated as at 26 to provide a vent integral with the valve mechanism. The length and the diameter of the metering pipe dictate its volumetric capacity and therefore the increment or slug of material to be conveyed and delivered by the system. In operation, discrete material, for example particulate coal which may be that designated 'small' i.e. 25 mm to zero in size, is introduced into the vessel 2 through inlet 6, the valve 8 having been opened as a first step in the cycle. After the vessel has been filled with the coal, the valve 8 is closed and the vessel is pressurised pneumatically through lines 30,32. As a result, the coal moves down within the vessel 2 to fill the elbow joint 12.Whilst the pressurisation is maintained, the first ball valve 14 is opened and coal is forced through the valve into the metering pipe 18, the coal abutting the ball 24 of the second valve 22 and the conveying air venting through the perforations 26.

The metering pipe 18 is thus completely filled with a specific volume and thus weight of coal. The first ball valve 14 is then closed against the head of coal leaving the metered quantity of coal in the pipe 18.

The second ball valve 22 is then opened and compressed air is introduced through the injector 16 to impel the coal slug along the conveying pipeline (not shown) which is attached via a reducer 38 to the discharge side of the second ball valve 22.

The valve 22 is then closed and the cycle is repeated at preset intervals as required to give an accurate feed of a predetermined quantity of coal on each occasion. This is a prime advantage of the present invention which is of relatively simple configuration and operation. The system is particularly, although not exclusively, useful as a feeder for boilers or furnaces to which specific quantities of fuel need to be delivered.

1. A pneumatic feeder system including a pressure vessel, an inlet to the vessel, a valve associated with the inlet, an outlet from the vessel, a metering pipe coupled to the outlet, a first valve associated with the metering pipe at the entry thereto, a second valve downstream of the first valve at the exit from the metering pipe, and a vent arranged in the second

**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 pneumatic feeder systems This invention concerns improvements in or relating to pneumatic feeder systems. In particular, the invention has reference to such systems used for the conveyance and delivery of discrete materials, for example particulate coal, in metered quantities. In combustion equipment, it is highly desirable to be able to introduce fuel at a predetermined measured rate for control purposes to ensure that combustion proceeds with the appropriate intensity in relation to the heat output required. This requirement is especially important for boilers and more particularly so for those employing fluidised bed combustion which is sensitive to variations in fuel feed input rates. Pneumatic feeder systems are known and generally include a pressure vessel into which the material is introduced through a valved inlet. Valving is arranged in a conveying pipe downstream of the vessel which in use is pressurised to provide the impetus for conveying the material then the valve is open. In some systems, a further air injection is provided in the conveying pipe. Systems of the known type are perfectly adequate when the delivered quantity of material is neither important nor critical. However, in operational circumstances where the material quantity is important, for example in the applications indicated above, the conventional feeder systems are inadequate. An object of the invention is to provide an improved pneumatic feeder system which enables accurate quantities of material to be conveyed and delivered to a user location. According to the invention a pneumatic feeder system includes a pressure vessel, an inlet to the vessel, a valve associated with the inlet, an outlet from the vessel, a metering pipe coupled to the outlet, a first valve associated with the metering pipe at the entry thereto, a second valve downstream of the first valve at the exit from the metering pipe, and a vent arranged in the second valve. Preferably the first and second valves are ball valves spaced apart a distance determined by the length of the metering pipe, the dimensions of which define the quantity of material to be discharged by the system incrementally. The vent in the second valve is conveniently formed by perforations in the ball. An air injector is advantageously provided in the metering pipe intermediate the first and second valves, preferably adjacent and downstream of the first valve. Means are provided for pressurising the pressure vessel such as in use to impel a charge of material into the metering pipe, the first valve being open. The pressure vessel is preferably orientated with its axis vertical, the metering pipe extending either coaxially vertical therewith, or disposed horizontally, an appropriate elbow connection being provided between the outlet of the pressure vessel and the metering pipe. By way of example only, one form of pneumatic feeder system is described with reference to the accompanying drawing which is a general arrangement of the system. Referring to the drawing, a pneumatic feeder system shown generally at 1 includes a pressure vessel 2 of inverted hollow frusto - conical form having a domed cap 4 incorporating an inlet 6 with which is associated a solenoid controlled pneumatic charging valve 8. The pressure vessel 2 has a flanged outlet 10 coupled via an elbow joint 12 to a solenoid controlled pneumatically operable ball valve 14 adjacent to which and downstream thereof is an air injector 16. A metering pipe 18 of predetermined length is coupled to the injector 16 and has located at its exit 20 a second solenoid controlled pneumatically operable ball valve 22, the ball 24 of which is perforated as at 26 to provide a vent integral with the valve mechanism. The length and the diameter of the metering pipe dictate its volumetric capacity and therefore the increment or slug of material to be conveyed and delivered by the system. In operation, discrete material, for example particulate coal which may be that designated 'small' i.e. 25 mm to zero in size, is introduced into the vessel 2 through inlet 6, the valve 8 having been opened as a first step in the cycle. After the vessel has been filled with the coal, the valve 8 is closed and the vessel is pressurised pneumatically through lines 30,32. As a result, the coal moves down within the vessel 2 to fill the elbow joint 12.Whilst the pressurisation is maintained, the first ball valve 14 is opened and coal is forced through the valve into the metering pipe 18, the coal abutting the ball 24 of the second valve 22 and the conveying air venting through the perforations 26. The metering pipe 18 is thus completely filled with a specific volume and thus weight of coal. The first ball valve 14 is then closed against the head of coal leaving the metered quantity of coal in the pipe 18. The second ball valve 22 is then opened and compressed air is introduced through the injector 16 to impel the coal slug along the conveying pipeline (not shown) which is attached via a reducer 38 to the discharge side of the second ball valve 22. The valve 22 is then closed and the cycle is repeated at preset intervals as required to give an accurate feed of a predetermined quantity of coal on each occasion. This is a prime advantage of the present invention which is of relatively simple configuration and operation. The system is particularly, although not exclusively, useful as a feeder for boilers or furnaces to which specific quantities of fuel need to be delivered. CLAIMS

1. A pneumatic feeder system including a pressure vessel, an inlet to the vessel, a valve associated with the inlet, an outlet from the vessel, a metering pipe coupled to the outlet, a first valve associated with the metering pipe at the entry thereto, a second valve downstream of the first valve at the exit from the metering pipe, and a vent arranged in the second valve.

2. A system according to claim 1 in which the first and second valves are ball valves.

3. A system according to claim 2 in which the vent in the second valve is formed by perforations in the ball.

4. A system according to any one of the preceding claims in which an air injector is provided in the metering pipe intermediate the first and second valves adjacent and downstream of the first valve.

5. A system according to any one of the preceding claims in which means are provided for pressurising the pressure vessel and for propelling a charge of material in use into the metering pipe.

6. A system according to any one of the preceding claims in which the pressure vessel is orientated with its axis vertical, the outlet being in the base of the vessel.

7. A system according to claim 6 in which the metering pipe is orientated horizontally.

8. A system according to claim 6 in which the metering pipe is orientated vertically and coaxially with the pressure vessel.

9. A system according to any one of the preceding claims in which the first and second valves are pneumatically operable solenoid controlled valves.

10. A pneumatic feeder system substantially as hereinbefore described with reference to the accompanying drawing.