Horizontal drums

With hafQes Horizontal drum Double cone revolving around long axis Twin shell Ciihe Twin rotor Tiirhine Paddle mixer Sifter (tiirhosifter) Attrition mill Elevator loading Pneumatic conveying Vibrating... 

Horizontal Blowdown Drum/Catch Tank This type of drum, shown in Fig. 26-16, combines both the vapor-liquid separation and holdup functions in one vessel. Horizontal drums are commonly used where space is plentiful, such as in petroleum refineries and petrochemical plants. The two-phase mixture usually enters at one end and the vapor exits at the other end. For two-phase streams with very high vapor flow rates, inlets may be provided at each end, with the vapor outlet at the center of the drum, thus minimizing vapor velocities at the inlet and aiding vapor-hquid separation. 

For small volumes of liquid, it may be necessary to provide more liquid surge than is necessary to satisfy the L/D > 3. Otherwise this criteria should be observed. If the required liquid surge volume is greater than that possible in a vessel having L/D < 5, a horizontal drum must be provided. 

A reladvely simple example of a HAZOP study using guidewords is shown for a boiler drum in Fig. 15.7.1 and Table 15.7.2. The intent of die operation is to maintain die water level in die horizontal drum between 30 and 40% of die volume. 

Horizontal vessels as cylinders are generally more suitable for diameters up to about 8 feet than other shapes, or vertical, due in part to the increased interfacial area for interface formation. For a horizontal drum (See Figure 4-12) ... 

When a-sulfo fatty acid esters are used as the major active component in detergents they can cause problems because of their foaming properties. In European horizontal drum-type automatic washers they produce too much foam, and in the rinse cycle of the American and Japanese pulsator-type washers the foam cannot be completely rinsed out [38]. The problem of inefficient rinsing can be solved by the addition of soap [63] or sulfonated unsaturated fatty acid esters [64]. For European applications special foam inhibitors are needed. 

The water can be assumed to be dispersed in the hydrocarbon. Estimate the size of decanter required to separate the mixture in a horizontal drum with a length to diameter ratio of 3 to 1 and an interface across the center of the drum. 

So far, we have only been talking about washing machines in general without differentiating between the various types. In terms of construction, the washing machines most frequently available on world markets can be divided into two groups, those with a horizontal drum axis and those with a vertical drum axis as shown in Fig. 3.1. 

Roseman B, Donald MB. Mixing and de-mixing of solid particles part 2 effect of varying the operating conditions of a horizontal drum mixer. Br Chem Eng 1962 7(1) 823. 

Thermal cracking or pyrolysis, the oldest of the these processes,1 was first carried out by Burton2 in his treatment of the residue remaining from the distillation of volatile components (so-called straight-run gasoline) of oil. The residue was treated in a horizontal drum by heating to 450-550°C under 5-6 atm. The volatile components were distilled off continuously until only coke remained in the still. The Burton process was supplanted by the continuous Dubbs process Operating... 

L, Extended length of inlet nozzle (horizontal drum)... 

Eq. (20), (21). (27), (28) and (29) constitute the basic equations for the vapor-phase sizing of the horizontal drum separator, both the gravity settler and the impingement. 

Horizontal drum design—an example The following example from API-521, p. 47 (1st ed.) will serve to illustrate the application of the equations that have been developed ... 

A wire-mesh pad in a horizontal drum greatly enhances separation and significantly reduces drum size. For lower pressure drop across the pad. the requirement for a high-performance pad can be relaxed by designing so the vapor space removes larger droplets, reducing the load on the pad. 

The design-base particle diameter to be separated in the vapor space should not exceed the pad-disengage-mt-nt droplet diameter. 1). To be on the safe side, a maximum droplet diameter should be limited to 400 pm. In horizontal drum design, the mesh pad should be regarded as a polisher for removing small droplets not separated in the vapor space—i.e., as a secondary mechanism in vapor-liquid separation... 

The design of liquid-phase separation in the horizontal drum (both gravity and impingement types) is identical to that for the vertical drum. 

The diameter again is figured from the volumetric rate of the vapor and the linear velocity from Eq. (18.9). Since the upward drag of the vapor is largely absent in a horizontal drum, however, the coefficient K often is raised by a factor of 1.25. Example 18.3 deals with the design of both kinds of drums. 

Flat sheets can be made using a rotating cylinder with lips on the ends. The cylinder must be level to ensure even thickness. The polyurethane mixture is added to the bottom of the horizontal drum, which is rotated at a speed of between 2 and 15 revolutions per minute. The thickness of the sheet is controlled by the weight of polyurethane added. The speed of rotation must be adjusted to suit the diameter of the cylinder and the viscosity of the mixture. The cylinder must be fully coated before gelation starts. 

Finally, an agglomerator design combining features of both the inclined disc and the horizontal drum should be noted. This machine, known as a cone pelletizer, is described in Fig. 3.17 and Table 3.4. As the name implies, the vessel is in the form of a truncated cone and the scraped inner surface has a bowl-like shape as build-up takes place during operation. The cone... 

Fig. 8.4. Construction of slowly-revolving horizontal drum for sludge dewatering [15] the Dehydrum . (Reprinted with permission of the American Water Works Association from Journal AWWA, Volume 67, Copyrighted 1975.)...

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