1. Field of the Invention
The invention relates to a conveyor, e.g. for coal, with a conveyor box and with a substantially cylindrical housing which is spaced from and surrounds the conveyor box.
When coal is fed to coal pulverisers for coal dust furnaces the conveyors used must have a pressure-tight housing in order to withstand not only the operating pressure, which is higher than the atmospheric pressure, but also the pressure of an explosion which may occur in the interior of the coal pulveriser and be propagated upstream into the conveyor.
2. Description of the Prior Art
In order to satisfy these requirements, a conveyor of the type described above is known (British Pat. No. 2065586) which has a cylindrical housing which surrounds the conveyor box and is spaced from it and wherein the gap between conveyor box and housing wall is packed with a fire-inhibiting plastic foam. This plastic foam is intended to transfer the internal pressure, which occurs when there is an explosion, uniformly to the cylindrical housing wall, which is in turn dimensioned so that it can withstand the explosion gas pressure.
It is doubtful in the case of the known apparatus whether the pressure is actually transmitted uniformly to the total cylindrical housing wall. Above all, however, it is disadvantageous that the trays and side walls of the conveyor, which suffer heavy wear, are connected to the plastic foam over their entire surfaces after the cavities have been foamed, and can then no longer easily be removed or exchanged. However, this removal is necessary because the side walls and trays of the conveyor box have a considerably shorter useful life than the housing surrounding the conveyor, due to corrosion and due to the wearing effect of the conveyor chains of the conveyor.