Drum Materials

Since C-VfcMo plate is supplied in the as-rolled condition in the thickness normally used for coke drums (-1 in. [25 mm] thick), the toughness is usually poor. To obtain improved toughness at minimal cost, one should specify that the C- Mo be made to fine grain practice. Most coke drums have been made of iCr-v Mo materials for about the last 15 y because of the controversy over C-V Mo and the higher allowable 

Fluid Coking and Cracking, Delayed Coking, Alkylation, Sulfur Plants, and Sour Water Strippers 

Delayed cokers are usually clad with 12Cr to avoid high-temperature sulfur attack. For cladding, type 4f OS (UNS S41008) SS is preferred over type 405 (UNS S40500) SS because the higher chromium in type 405 SS causes problems with forming and 885°F (475°C) embrittlement (discussed in Chapter One). 

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Blowdown drum materials must be adequate for any corrosive substance that may be released into it, and for the temperamre limits defined. 

An account is given of exotherm and foaming consequent upon adding the acid to a waste solvent drum materials known to be present were xylene and and butyl chloride [1]. Sulfuric acid would catalyse the Friedel Crafts reaction of these, evolving hydrogen chloride, though immiscibility means a delay might be expected and reaction seems to have been immediate [2]. 

Let us now examine changes in mineral adhesion that are related to the choice of drum material [137]. For the separation of powders such as quartz, magnetite, hematite, pyrite, barite, asbestos, and j3-spodumene, the yield of the retained fraction on brass and aluminum surfaces was found to vary from 26 to 50%, and on tin plate and steel from 46 to 66%. The adhesion of these powders to tin plate and steel was greater than the adhesion to brass or aluminum. 

The yields of retained fraction for coal and coal constituents, depending on the drum material, were found to be as follows [137] ... 

Yield (in %) of retained fraction with indicated drum material brass. 

We can see from these data that the yield of retained fraction can be changed approximately twofold by the choice of drum material. 

These examples show that by changing the drum material and drum surface, or the particle size and shape, we can change the magnitude of adhesive interaction and the yield of the retained fraction. Variation of particle size gives the greatest possibilities for changing the adhesive force. 

One production line of a paper mill consists according the size and the quality of the produced paper sometimes from more than 50 steam drums to dry and flatten the produced paper. These drums (cylinders with flat bottoms, see figure 1) will be used with a steam pressure up to 500 kPa (5 bar) and additionally with a rotation speed up 1200 m.min the material is mainly grey cast iron (with lamellar graphite). The diameters can reach up to 2.2 m and the cylindrical lengths up to 10 m. For the specific flattening drums the cyhndrical diameters can be up to 5 m and more. 

A fatal accident and some other disasters, which were caused by small cracks, lead to a more strict consideration of the security of these steam drums. Parallel to these the economical pressure, due to the globalisation of the today s industry, lead to the increase of the pressure and the rotation speed of the paper production machines for a higher output of the production, which means, that all safety aspects from the design and the material will be exploited totally. On the other hand cast iron is also not a ductile and comfortable material, like the most steels for the pressure equipment. 

Based on our practical experiences in the applieation of AE on pressure equipments since 1979, we started in the year 1994 to apply AE on steam drums in combination with pneumatic tests. Before we are able to do this, we have to perform extensive lab tests with the specific material (grey cast iron and cast steel) from which these drums are produced. 

Plastic bags Plastic beads Plastic bearing materials Plastic cements Plastic drums Plastic electronic package Plastic encapsulant... 

Drum Dyers. Indirect-heat dmm dryers, like spray dryers, are usable only for materials that are fluid initially and pumpable. Drying is effected by applying a thin film of material onto the outer surface of a rotating heated dmm using appHcator roUs, spray nozzles, or by dipping the dmm into a reservoir. Usually the dmm is cast iron or steel and chrome-plated to provide a smooth surface for ease of product release by doctoring. Dmm rotational speed is such that... 

Guard and safety Raw-material and finished-product storage—tanks, spheres, drums, bins. 

Portable tanks, drums, or bottles are shipped by rail, ship, air, or truck. Portable tanks containing hazardous materials must conform to DOT regulations. Parts 173 and 178, Siibpart H. 

Rotating-Drum Type This type (Fig. 11-55 a and b) is not an adaptation of a material-handling device (though volumetric material throughput is a first consideration) but is designed specifically for... 

The burden must have a definite sohdification temperature to assure proper pickup from the feed pan. This limitation can be overcome by side feeding through an auxiliary rotating spreader roll. Apphcation hmits are further extended by special feed devices for burdens having oxidation-sensitive and/or supercoohng characteristics. The standard double-drum model turns downward, with adjustable roll spacing to control sheet thickness. The newer twin-drum model (Fig. ll-55b) turns upward and, though subject to variable cake thickness, handles viscous and indefinite solidification-temperature-point burden materials well. 

Not appbcable Not applicable Suitable for thin or mechanically weak sheets which can be dried in contact with a heated surface. Special surface effects obtainable Suitable for materials which need not be dried flat and which will not be injured by contact with hot drum... 

The turbo-tray dryer can handle materials from thick slurries [1 million (N s)/m (100,000 cP) and over] to fine powders. It is not suitable for fibrous materials which mat or for doughy or tacky materials. Thin slurries can often be handled by recycle of dry product. Filter-press cakes are granulated before feeding. Thixotropic materials are red directly from a rotary filter by scoring the cake as it leaves the drum. Pastes can be extruded onto the top shelf and subjected to a hot blast of air to make them firm and free-ffowing after one revolution. 

Rotary Drum Filters The rotaiy drum filter is the most widely used of the continuous filters. There are many design variations, including operation as either a pressure filter or a vacuum filter. The major difference between designs is in the technique for cake discharge, to be discussed later. All the alternatives are characterized by a horizontal-axis drum covered on the cylindrical portion by filter medium over a grid support structure to allow drainage to manifolds. Basic materials of construc tion may be metals or plastics. Sizes (in terms of filter areas) range from 0.37 to 186 m (4 to 2000 ft ). 

Alternating-polarity drum separator. This device is used for the treatment of coarse material (minus 40 mm, plus 0.15 mm) containing strongly magnetic particles when a high-grade concentrate is required. The capacity of this device varies with feed-particle size, up to 100 t/(h m). 

Unigap drum separator. This device is used for materials finer than 6 mm at feed rates of up to 10 t/(h m). 

High-speed, low-intensity drum magnetic separator. This device is designed to handle very fine material (minus 0.15 mm and finer) to produce a high-grade magnetic concentrate. 

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