Refractory lining wear

Refractory lining wear in blast furnaces is monitored by radioactive tracers. Sources of Co are embedded in refractory bricks during lining. The y rays of Co are monitored from outside the furnace and erosion of the bricks is detected as the extinction of the y rays. Tritiated water ( H20) provides a very sensitive way of testing watertightness of pieces connected with elastomer joints. 

Current designs for venturi scrubbers generally use the vertical downflow of gas through the venturi contactor and incorporate three features (1) a wet-approach or flooded-wall entry section, to avoid dust buildup at a wet-dry junction (2) an adjustable throat for the venturi (or orifice), to provide for adjustment of the pressure drop and (3) a flooded elbow located below the venturi and ahead of uie entrainment separator, to reduce wear by abrasive particles. The venturi throat is sometimes fitted with a refractory lining to resist abrasion by dust particles. The entrainment separator is commonly, but not invariably, of the cyclone type. An example of the standard form of venturi scrubber is shown in Fig. 17-48. The wet-approach... 

In a gasifier utilizing gas or liquid as a carbon source, refractory failure is primarily caused by thermal, chemical, and structural wear of the refractory liner. The hot face refractory lining in the gasifier is typically a dense high-alumina material (low in Si02 and FeO), followed by a porous layer composed of a material such as... 

The heart of this facility is a refractory-lined reactor cylinder with 20 cm in-diameier and a total height of about 6.5 m. The internal refractory forms two concentric cylinders (each one of thickness 6.5 cm) with different thermal conductivity and wearing properties. Additionally, the reactor tube, the cyclone and the recycling line are protected with outside insulation in order to minimise heat losses. The gasifier components (raiser, cyclone and standpipe) are equipped with ten thermocouples (K-type) and pressure transducers. The thermocouples probes are connected to a computer based data acquisition and control system. In addition, the feed rates of gasification... 

To allow for long campaign operation the following measures need to be taken apply a more persistent refractory lining of the shaft, bottom and the hearth apply water cooling of the furnace wall this keeps the wall temperature low and thus prevents rapid wearing of the hearth lining... 

The coating in the burning zone protects the refractory lining from wear and improves the thermal insulation of the kiln wall. As a rule, therefore, coating is a desirable feature. However, under adverse conditions it may become too thick or, as already mentioned, form objectionable rings. There are various methods of removing such excess features. 

To protect the shell against the effect of condensed acid vapours, the internal surfaces of the steel shell may be provided with an anticorrosion coating. When no refractory lining is used the surfaces shall be corrosion and wear resistant. 

The internal structure and refractory lining of the combustion chamber are subject to wear and corrosion, which limits their service life. Consequently, appropriate apertures for repair or replacement of the contaminated refractories shall be provided. 

Similar to the plastic refractory materials, ramming materials can have a ceramic or chemical (chemical ceramic) bond. Table 15 shows the properties of several ramming mixes, which, if installed properly, can be an excellent refractory lining. This is especially the case if liquid phases, slags, melts, etc., and thermal shock resistance are the main stress factors for the wear layer. The physical properties of these materials are comparable to those of dry-pressed refractory bricks. The production of ramming mixes is on the decline for two main reasons ... 

Primary diplegs internally lined with I inch (2.5 cm) thick, erosion-resistant lining. Secondary diplegs lined internally with I inch refractory on the top 5 feet (1.5 m) from the dust-bowl. Externally, diplegs should be lined where the spent catalyst returns and other known turbulent or wear areas. 

When heavier refractories are required because of operating conditions, insulating brick is installed next to the shell and firebrick is installed to protect the insulating brick. Industrial experience in many fields of application has demonstrated that such a lining will successfully withstand the abrasive conditions in the bed for many years without replacement. Most serious refractory wear occurs with coarse particles at high gas velocities and is usually most pronounced near the operating level of the fluidized bed. 

Catalyst-carrier lines. Catalyst-carrier lines as large as 105 in. in diameter are used (271). To provide wear resistance, these pipes are ordinarily lined with refractory castable cement reinforced by steel mesh which is welded directly to the inside of the line. In midget fluid units, however, alloy-steel carrier lines may be used in direct contact with the catalyst, because the small size of the lines makes it difficult to install internal insulation (237). Counterweights are used to help support long carrier lines, and shock absorbers have been employed in order to minimize vibration or jiggling (20). 

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