WO2010131213A1

WO2010131213A1 - Refractory lining of cooled pipes

Info

Publication number: WO2010131213A1
Application number: PCT/IB2010/052112
Authority: WO
Inventors: Antonio Ture
Original assignee: Refrasud International Srl
Priority date: 2009-05-15
Filing date: 2010-05-12
Publication date: 2010-11-18
Also published as: ITBA20090019A1; EP2430382A1

Abstract

Refractory lining of pipes cooled by water or other coolant, constituting the structure of furnaces for heating slabs, pipes or steel plates. Said lining is made up of a metal structure (sheet) and prefabricated supplemented concrete characterized by a low coefficient of thermal conductivity. According to different embodiments, the inventive object solves the problem of the anchorage of the refractory product to the pipe to be lined. Finally, in order to reduce the coefficient of thermal conductivity even more, between the metal sheet and the concrete it can be provided an inter-space to be filled with a layer of insulating material or to be left empty.

Description

REFRACTORY LINING OF COOLED PIPES

DESCRIPTION

Object of the present invention is a refractory lining of pipes constituting the structure of furnaces for heating steel semifinished products, which is structurally similar to the one described in the European patent EP 1181259 but different in the fixing to the tube. The furnaces for heating steel semi-finished products (slabs, pipes, plates) are usually provided with a supporting structure made up of pipes cooled by water or other coolant. Since the working temperatures of said furnaces are greater than 1300⁰C, the pipes need to be lined by a refractory lining which limits the loss of heat, that is to say the heat absorption by the coolant. The linings known so far are made up of concrete castings laid during installation, prefabricated concrete or coverings in ceramic fibre or other refractory material. However, the already known applications have significant disadvantages: the linings in concrete are disadvantageous for a great coefficient of thermal conductivity and, moreover, the installation times for the casting concrete are very long. The linings in ceramic fibre, instead, are disadvantageous because of their great toxicity grade, even though they have a low coefficient of thermal conductivity.

As already stated, the object of the present invention is structurally similar to the refractory lining described in EP 1181259, since it is as well a refractory lining or "covering" for cooled pipes made up of a metal structure (sheet) and prefabricated supplemented concrete characterized by a low coefficient of thermal conductivity. Said additive can be similar to the one described and claimed in the Italian patent for industrial invention n° 01243638. In this case, it is different from said patent in the different type of anchorage of the refractory product to the pipe to be lined, thus facilitating, for example, the application to the product to be lined. Yet, another new important aspect of the present invention is that it reduces the coefficient of thermal conductivity even more, by using a thin layer of insulating material between the metal sheet and the concrete, or by leaving an empty inter-space. These and other advantages will be highlighted in the detailed description of the invention, specifically referring to the drawings 1/5 to 5/5, which by way of example show different, not limiting, preferred embodiments. In particular: fig. 1 shows a tridimensional view of the refractory lining in its two variants with full or empty inter-space between sheet and concrete; figs. 2a and 2b show a first embodiment of the refractory lining in the case of horizontal module with inter-space to be filled with insulating material; figs. 3a and 3b show again the first embodiment of the refractory lining, in the case of vertical module, yet with the inter-space to be filled with insulating material; figs. 4a and 4b show a second embodiment of the refractory lining in the case of horizontal module with empty inter-space; figs. 5a and 5b show again the second embodiment of the refractory lining, in the case of vertical module, yet with empty inter-space. As it is shown in fig. 1 , the refractory lining 1 has to wrap the single pipe and, from the outside to the inside, it is made up of prefabricated blocks in supplemented concrete 2, an inter-space 3 to be filled with suitable insulating material or to be left empty, a shaped sheet 4 in direct contact with the pipe and a fixing system 5 to make the opposite blocks of concrete (or coverings) adhere to each other. Said fixing system is made up of a tab 5\ perpendicularly welded to the sheet on a covering, and a hook 5", welded on the opposite covering, almost crook- shaped, which is so shaped that it couples with the tab 5¹ to guarantee the coupling between the two coverings. So, depending on the shape of the pipe to be lined (horizontal or vertical), different construction modes of the same lining are possible.

Figs. 2a and 2b show a first embodiment of the lining in the case of horizontal pipe. The single block is made up of the sheet 4 wrapping the pipe, or possibly the couple of welded pipes, an intermediate layer 3 to be filled with suitable insulating materials as for example rock wool impregnated with fire-retardant paint or simple cardboard and the layer of refractory supplemented concrete 2. The sheet 4 is provided, in turn, with a series of anchorages 6 extending inside the concrete to increase the sealing of the same. The additive can be similar to the one described and claimed in the Italian patent for industrial invention n° 01243638, that is to say it is made up of a plurality of carbonates and, after calcination, it is characterized by the following weight %ages: 0-1 % Fe2O3, 65-80% CaO, 20- 30% SiO2, 0-2 AI2O3 and 0-1 % MgO. In this case, the coupling system 5, made up of the tab 5¹ and the hook 5", is provided only in the lower portion of the pipe since in the upper portion, the same pipe is directly welded to the structure.

Similarly in figs. 3a and 3b, it is shown again the first embodiment of the refractory lining with the inter-space 3 to be filled with suitable insulating material, but in case of vertical pipe. The structure as a whole is unchanged, with the sheet 4 wrapping the pipe provided with anchorages 6 for gripping in the concrete and with anchorage system 5, which is now provided in the upper portion as well as in the lower portion of the pipe (fig. 3a).

Figs. 5a and 5b are completely similar to figs. 2a and 2b and relate to the refractory lining for horizontal pipe with the only variant of the inter-space 3, which in this case is empty, yet guaranteeing optimal insulating properties. For the same reason, figs. 6a and 6b are completely similar to figs. 3a and 3b too, and relate to the refractory lining for vertical pipe, yet with empty inter-space 3. The anchorage system 5 made up of a tab 5¹ and a complementary shaped hook 5", provided in each different type of embodiment of the refractory product, is considerably advantageous with respect to the previous solutions, such for example fixing pins or hinged systems, above all concerning the mounting and demounting easiness of the product from the pipe to which it is to be applied.

Claims

1) Refractory lining (1) of pipes cooled by water or other coolant, constituting the structure of furnaces for heating slabs, pipes or steel plates, made up of two portions, each one comprising a metal structure (4) and prefabricated supplemented concrete (2) with low coefficient of thermal conductivity, characterized in that the coupling system of the refractory lining is made up of a coupling between a tab (5¹) perpendicularly welded to the sheet (4) on a covering and an almost crook- shaped hook (5"), welded on the sheet of the opposite covering, shaped so that it couples with the tab (5¹) to guarantee the coupling between the two coverings.

2) Refractory lining according to claim 1 , characterized in that said additive is similar to the one described and claimed in the Italian patent for industrial invention n° 01243638, that is to say it is made up of a plurality of carbonates and, after calcination, it is characterized by the following weight %ages: 0-1 % Fe2O3, 65-80% CaO, 20-30% SiO2, 0-2 AI2O3 and 0-1 % MgO.

3) Refractory lining according to any one of the preceding claims characterized in that, in order to reduce the coefficient of thermal conductivity even more, it further comprises an intermediate inter-space (3) between the metal sheet (4) and the concrete (2) to be filled during installation with insulating materials or to be left empty. 4) Refractory material according to any one of the preceding claims, wherein the sheet (4) wrapping the pipe or the couple of pipes comprises a series of metal anchorages (6) extending inside the concrete (2) to increase the sealing of the same concrete.