GB2121313A - Method of lining vessels - Google Patents

Abstract

A method of lining a vessel, e.g. a fluidised bed chlorinator or a furnace, with a fired refractory concrete in which at least part of the lining is shaped in segments 17 separated at least vertically from adjacent segments by spacing members 14 of refractory material which is easily friable. After firing of the segments of the refractory composition the spacing members are removed creating gaps of known location and size which are then filled with a refractory composition which is then fired. The method produces a refractory lining in which any cracks initially introduced are in known positions and of very small size. <IMAGE>

Description

SPECIFICATION Method of lining vessels The invention relates to a method of lining a vessel and particularly to a method of lining a vessel with a fired-refractory material.

Hitherto the production of fired linings of socalled "plastic" refractory compositions has almost invariably resulted in the production of cracks which on cooling after the firing process have required sealing with ceramic fibrous material. During subsequent use at high temperature the cracks remain sealed by the fibres which are held under compression but on cooling, say to enable inspection to take place or for some other purpose, the cracks tend to open again. Prior to use again the cracks have required refilling with the fibres. Any failure to fill the cracks properly can result in damage to the vessel wall and/or escape of noxious fumes from the vessel.

These cracks produced on firing are of varying size and randomly located and it is desirable that control should be exercised over the size, location and frequency of these cracks. A reduction in the size of the cracks would be most beneficial if this avoided the need to fill the cracks with ceramic fibres.

According to the present invention a method of lining a vessel with a fired refractory lining comprises shaping at least part of the lining of a refractory composition curable by firing, firing the composition until an adequate state of cure has been achieved and allowing the lining to cool in which process at least a part of the lining is applied in sections divided at least vertically by spacing members of a refractory material easily friable when compared to said fired refractory composition, said spacing members have a width between adjacent sections of refractory composition sufficient to provide a gap readily fillable, removing the spacing members after firing and cooling the refractory composition, filling the gaps so created between adjacent sections of fired refractory composition with uncured refractory composition, firing the vessel again to cure the uncured refractory compositions in said gaps.

The method of the invention in applying the refractory composition in the form of a segmented lining has a major advantage over previous methods of lining. The spacing members on removal produce gaps, the position, size and frequency of which is controlled and there is little or no other cracking of the lining. These gaps are then filled and after firing there may be cracks between the newly inserted composition in the gap and the segments but the size is so small that no further action is needed.

The method is of particular advantage for use in the lining of vessels and in the repair of lining of vessels to be used to contain fluid beds in which ingress of bed material into cracks can produce highly disadvantageous situations resulting in breakage of the lining and damage to the vessel wall in addition to other happenings mentioned hereinbefore. In such vessels the method can be used to line the inner wall in the region only of the fluid bed material or can be used to line the whole of the wall. The method can also be used to produce a refractory lining in a chosen inner area of only part depth of the overall depth of lining of the vessel such as in repair of a lining or initially on lining the vessel to produce a dual lining composition.

The method is used at least to introduce vertical spacing members and preferably also horizontal spacing members are employed to divide the lining into rectangular sections.

Although generally after removal of vertically aligned spacing members there is no need to employ temporary supports in the gaps it is advisable, depending on the particular structure of the vessel, to insert spaced supporting pieces of a suitable material into horizontal gaps to support any upper area of lining which could move downwardly to close a gap. Such spaced supporting pieces may be allowed to remain in the gap after they have been filled and fired. Typically these small supporting pieces may be formed of a fired composition similar to that forming the lining and/or to that used to fill the gaps.

The spacing members used to separate the areas of lining are of a material which is more friable than the lining when fired which enables the spacing member to be removed to produce the gap. The spacing member can be produced from a refractory or ceramic composition having a reduced amount of bonding agent as compared to the refractory lining. Alternatively any other suitable composition can be used to pre-form the spacing members, The size and number of the spacing members depends on the size of the vessel to be lined and on the particular use to which it is to be put. For a cylindrical vessel with its longitudinal axis vertically aligned the vertical spacing members can be arranged conveniently at distances of from 100 cm to 1 50 cm apart at their innermost edges.

The method of the invention is of particular use in lining vessels to be used at high temperatures such as furnaces, chlorinators and other reactors or treatment vessels. The method can be employed very successfully to line a chlorinator vessel for a titaniferous material such as mineral rutile in which the mineral rutile in finely divided form is chlorinated with chlorine gas in the presence of a carbonaceous reducing agent to produce, after separation of impurities and other metallic chlorides, gaseous titanium tetrachloride which can be used in the production of pigmentary titanium dioxide. Usually the finely divided mineral rutile is maintained in fluid suspension by the passage upwardly through a bed of the rutile of the chlorine gas.

Methods of lining a vessel will now be described in detail by way of example only with reference to the accompanying drawings in which: Figure 1 is a sectional view of a chlorinator, Figure 2 is a further sectional view of the chlorinator during lining thereof, Figure 3 is a horizontal cross-sectional view of the chlorinator of Figure 2, and Figure 4 is a horizontal cross-sectional view of another chlorinator at a stage in the method similar to that of Figure 2.

As shown in Figure 1 the vessel consists of a metal (steel) shell 1 having a lining 2 of a fired refractory composition. The vessel has a lined lid 3, The base of the vessel is closed by an apertured base plate 4 carrying a gas distribution arrangement 5 including gas distribution tubes 6 in a refractory infill material 7. Below the base plate 4 is a wind box assembly 8 with a gas inlet pipe 9. In use the material forming the bed 10 of the material to be fluidised is carried on the gas distributor arrangement 5. The vessel is also provided with a gas outlet 11 and bed inlet means 1 2 situated in the wail of the vessel.

Figure 2 shows the vessel without the gas distributor arrangement 5 base plate 4 and wind box assembly 8 and during the method of lining of the vessel. Only the bottom half of the vessel in the region of the bed 10 is to be lined according to the invention employing spacing members. Prior to application of the lining lower spacing members 13 and upper spacing members 14 are positioned.

These members are formed of pieces of readily friable concrete having a width of say about 5 cm when used with a vessel having a diameter of about 5 metres. Horizontally positioned spacing members of similar thickness are positioned as shown 1 5 and 1 6. The lining 2 of refractory composition is then applied to the inner surface of the shell 1 The vessel is closed after the lining has been applied and the temperature raised to fire the composition. The fired vessel is then cooled and the spacing member 13, 14, 15 and 1 6 removed.

When the lower horizontal spacing members 1 5 are removed small support pieces are inserted to support the upper segments 17 of the lining. No small support pieces are required when the upper spacing members 1 6 are removed since the upper lining portion 1 8 is retained in position by outlet 11 and inlet 12 at least. These spacing members are removed by any suitable technique such as drilling.

The spaces produced by removal of the spacing members are then filled with additional refractory composition and the vessel heated again to fire the fillings.

On cooling it was seen that the lining in the region of the bed 10 contained very small cracks of no significance along the edges of the spacing members.

Cracks in the upper lining portion 18 are not a critical disadvantage and can be tolerated.

The particular refractory composition which can be used to form the lining of the vessel are such compositions curable by firing. Typical refractory compositions are those formed of a refractory concentrate containing an aggregate and say a high alumina containing cementitious binder. For instance a typical cementitious binder contains aluminium values in an amount of at least 50% by weight when expressed as Al2O3 and the most preferred binders containing aluminium values in an amount of at least 65% by weight when expressed as Awl203. Typical overall amounts of aggregate and binder in such compositions are such that the refractory composition contains aluminium values in an amount of from 44% to 50% by weight as Awl203, silicon values in an amount of from 40 to 45% by weight when expressed as SiO2 and iron values in an amount of up to 2% by weight when expressed as Fe2O3. The most preferred type of refractory composition which may be used to form the lining are those subject to high shrinkage e.g. one comprising a mixture of an aggregate being formed of a calcined clay containing aluminium in an amount of from 43 to 63% by weight and silicon in an amount of from 53% to 33% by weight of the aggregate and the binder being an aluminium phosphate composition in an amount of from 2 to 10% by weight.

Any other type of refractory composition curable by firing and suitable for the particular use to which the vessel is to be put may be used in the method of the present invention.

A modified method involves using the method of the invention for only a part of the thickness of the lining as shown in Figure 4. As shown the existing lining 2 continues to the base region 4 of the vessel but is thinner in the bottom half of the vessel The remainder of the required thickness of the lining is applied using the method of the invention using spacing members 21 of friable concrete between the segments 22 of the lining being provided. After firing of the segment concrete the members 21 are removed and the spaces filled with additioned refractory composition.

It will be appreciated that the lining 2 and the segments 22 can be of different composition if desired and that the method modified as shown in Figure 4 can be used to effect the repair of an existing lining by removing damaged refractory to a desired depth and not necessarily to the full depth of the lining.

Claims (10)

1. A method of lining a vessel with a fired refractory lining which comprises shaping at least part of the lining of a refractory composition curable by firing, firing the composition until an adequate state of cure has been achieved and allowing the lining to cool in which process at least a part of the lining is applied in sections divided at least vertically by spacing members of a refractory material easily friable when compared to said fired refractory composition, said spacing members having a width between adjacent sections of refractory composition sufficient to provide a gap readily fillable, removing the spacing member after firing and cooling the refractory composition, filling the gaps so created between adjacent sections of fired refractory composition with uncured refractory composition and firing the vessel again to cure the uncured refractory composition in said gaps.

2. A method according to claim 1 in which the lining is applied in sections divided horizontally by spacing members of a refractory composition easily friable when compared to said fired refractory composition.

3. A method according to claim 2 in which spaced supporting pieces are inserted in the horizontal gaps produced by removal of the spacing members.

4. A method according to claim 3 in which the supporting pieces are allowed to remain in the gap after filling thereof with uncured refractory composition.

5. A method according to any one of claims 1 to 4 in which the spacing members are formed of a refractory or ceramic composition with a reduced amount of bonding agent as compared to the refractory lining.

6. A method according to any one of the preceding claims in which the vertical spacing members are spaced apart at a distance of from 100 cm to 1 50 cm at their innermost edges.

7. A method according to any one of the preceding claims in which the lining is applied in segments having a thickness of only part of the total thickness of the lining.

8. A method according to any one of the preceding claims in which the lining is applied in segments in the region in which a bed of particulate material is to be maintained.

9. A method of lining a vessel substantially as described herein and shown in Figures 1 to 3 of the accompanying drawings.

10. A method of lining a vessel substantially as described herein and shown in Figure 4 of the accompanying drawings.