GB2025014A - Fluidisable Bed Combustion Chamber - Google Patents

Abstract

A fluidisable bed combustion chamber of the kind having a tubular heat exchange member 2, for example one or more cooling coils, in a bed 1 of fluidisable material, a heat exchange medium being arranged to flow through the heat exchange member 2. A container 10 for the fluidisable bed and the heat exchange member 2 are mutually movable in a vertical direction for the purpose of performing rapid control of the heat transmission between the fluidisable bed and the heat exchange member. Suitably, the heat exchange member 2 is stationary and the container 10 is vertically movable by means of hydraulic piston and cylinder assemblies 6. <IMAGE>

Description

SPECIFICATION Fluidisable Bed Combustion Chamber This invention relates to a fluidisable bed combustion chamber of the kind having a tubular heat exchange member in a bed of fluidisable material, through which heat exchange member a heat exchange medium can flow.

During operation of a combustion chamber of the kind referred to it is not normally possible to reduce the temperature of the bed below a certain level without causing a serious risk of incomplete combustion in the bed. One way of controlling the bed temperature is to divide the fluidisable bed into several sections which can be switched in and out as desired. This, however, usually results in a rather coarse and rather slow control.

Another way of achieving temperature control is to vary the amount of bed material, since the heat transmission to the heat exchange member is many times greater inside the bed material than above it. However, this method of control is also relatively slow, both in the upward and the downward direction.

The present invention aims to provide a combustion chamber of the kind referred to in which temperature control of the heat exchange member can be effected more rapidly and more accurately than in hitherto known fluidisable bed combustion chambers.

According to the invention, a fluidisable bed combustion chamber having a tubular heat exchange member in a bed of fluidisabie material, through which heat exchange member a heat exchange medium can flow, is characterised in that the fluidisable bed and the heat exchange member are mutually movable in a vertical direction for the purpose of performing rapid control of the heat transmission between the fluidisable bed and the heat exchange member.

If those cases where the tubular heat exchange member, for example one or more cooling coils, contains water or steam under a pressure which is much higher than the pressure in the fluidisable bed, it is often advantageous to make the fluidisable bed raisable and lowerable while the heat exchange member is stationary.

The invention will now be described, by way of example, with reference to the accompanying drawing, the single Figure of which is a schematic sectional view of a fluidisable bed combustion chamber in accordance with the invention.

The Figure shows a combustion chamber with a container 10 in which there is a bed 1 of fluidisable material. A fluidising medium for the bed material and a fuel are supplied to the bed in any conventional manner (not shown).

A cooling coil 2 is immersed in the bed material. The coil 2 is suspended in stationary manner from a roof 3 above the bed 1 and passes down to the bed through sealing lead-in tubes 4 in a wall of the container 10.

For varying the level of the bed surface 5, the container 10 is arranged to be vertically movable by hydraulic piston and cylinder assemblies 6. In this way it is possible to lower the bed very rapidly so that parts of the cooling coil 2 are released from the bed material, thus reducing the load on the cooling coil. This is of particularly great importance if the cooling coil constitutes the boiler of a steam boiler plant, in which case it is virtually impossible to perform any control of the liquid-filled coil.

Instead of making the container 10 movable, it may be stationary and the cooling coil 2 movable.

However, in view of the fact that the pressure in the cooling coil is normally much higher than in the container 10, it is as a rule easier to make the container movable despite its greater weight.

Claims

1. A fluidisabie bed combustion chamber having a tubular heat exchange member in a bed of fluidisable material, through which heat exchange member a heat exchange medium can flow, in which the fluidisable bed and the heat exchange member are mutually movable in a vertical direction for the purpose of performing rapid control of the heat transmission between the fluidisable bed and the heat exchange member.

2. A combustion chamber according to claim 1, in which inlet and outlet pipes of the heat exchange member are led in a vertical direction through sealing lead-in tubes in a wall of a container for the bed material.

3. A combustion chamber according to claim 1.

in which the heat exchange member is stationary and a container for the bed material is movable in a vertical direction.

4. A combustion chamber according to any of the preceding claims, in which the tubular heat exchanger comprises at least one cooling coil.

5. A fluidisable bed combustion chamber constructed and arranged substantially as herein described with reference to, and as illustrated in, the accompanying drawing.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fluidisable Bed Combustion Chamber This invention relates to a fluidisable bed combustion chamber of the kind having a tubular heat exchange member in a bed of fluidisable material, through which heat exchange member a heat exchange medium can flow. During operation of a combustion chamber of the kind referred to it is not normally possible to reduce the temperature of the bed below a certain level without causing a serious risk of incomplete combustion in the bed. One way of controlling the bed temperature is to divide the fluidisable bed into several sections which can be switched in and out as desired. This, however, usually results in a rather coarse and rather slow control. Another way of achieving temperature control is to vary the amount of bed material, since the heat transmission to the heat exchange member is many times greater inside the bed material than above it. However, this method of control is also relatively slow, both in the upward and the downward direction. The present invention aims to provide a combustion chamber of the kind referred to in which temperature control of the heat exchange member can be effected more rapidly and more accurately than in hitherto known fluidisable bed combustion chambers. According to the invention, a fluidisable bed combustion chamber having a tubular heat exchange member in a bed of fluidisabie material, through which heat exchange member a heat exchange medium can flow, is characterised in that the fluidisable bed and the heat exchange member are mutually movable in a vertical direction for the purpose of performing rapid control of the heat transmission between the fluidisable bed and the heat exchange member. If those cases where the tubular heat exchange member, for example one or more cooling coils, contains water or steam under a pressure which is much higher than the pressure in the fluidisable bed, it is often advantageous to make the fluidisable bed raisable and lowerable while the heat exchange member is stationary. The invention will now be described, by way of example, with reference to the accompanying drawing, the single Figure of which is a schematic sectional view of a fluidisable bed combustion chamber in accordance with the invention. The Figure shows a combustion chamber with a container 10 in which there is a bed 1 of fluidisable material. A fluidising medium for the bed material and a fuel are supplied to the bed in any conventional manner (not shown). A cooling coil 2 is immersed in the bed material. The coil 2 is suspended in stationary manner from a roof 3 above the bed 1 and passes down to the bed through sealing lead-in tubes 4 in a wall of the container 10. For varying the level of the bed surface 5, the container 10 is arranged to be vertically movable by hydraulic piston and cylinder assemblies 6. In this way it is possible to lower the bed very rapidly so that parts of the cooling coil 2 are released from the bed material, thus reducing the load on the cooling coil. This is of particularly great importance if the cooling coil constitutes the boiler of a steam boiler plant, in which case it is virtually impossible to perform any control of the liquid-filled coil. Instead of making the container 10 movable, it may be stationary and the cooling coil 2 movable. However, in view of the fact that the pressure in the cooling coil is normally much higher than in the container 10, it is as a rule easier to make the container movable despite its greater weight. Claims

1. A fluidisabie bed combustion chamber having a tubular heat exchange member in a bed of fluidisable material, through which heat exchange member a heat exchange medium can flow, in which the fluidisable bed and the heat exchange member are mutually movable in a vertical direction for the purpose of performing rapid control of the heat transmission between the fluidisable bed and the heat exchange member.

2. A combustion chamber according to claim 1, in which inlet and outlet pipes of the heat exchange member are led in a vertical direction through sealing lead-in tubes in a wall of a container for the bed material.

3. A combustion chamber according to claim 1.

in which the heat exchange member is stationary and a container for the bed material is movable in a vertical direction.

4. A combustion chamber according to any of the preceding claims, in which the tubular heat exchanger comprises at least one cooling coil.

5. A fluidisable bed combustion chamber constructed and arranged substantially as herein described with reference to, and as illustrated in, the accompanying drawing.