Drums design example

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 ... 

We now have a geometric design tool to analyze a flash drum. For example, we can determine the pressure needed to produce a vapor with 75 mol% benzene, the relative flow rates, and the composition of the liquid stream (Figure 4.60). 

Calculate the vapor-liquid separation of the gross overhead product at the conditions of temperature and hydrocarbon partial pressure existing in the reflux drum. These calculations are detailed in the design example. The detailed calculation procedure is as follows. 

Internal Rotary-Drum Filters An example of an internal rotary-drum filter is illustrated in Figure 14. The filter medium is contained on the inner periphery. This design is ideal for rapidly settling slurries that do not require a high degree of washing. Tankless filters of this design consist of multiple-compartment drum vacuum filters. 

A condensible blowdown tank, designed on a similar basis to that described above for phenol, may be provided in other services where a conventional condensible blowdown drum would not be acceptable (e.g., due to effluent water pollution considerations). Examples of such cases are methyl ethyl ketone (MEK) and dimethyl formamide (DMF). A suitable absorbing material is specified (e.g., a lube oil stock for MEK water for DMF), and the design must include consideration of maximum permissible operating temperatures to prevent excessive vapor evolution or the boiling of water. 

The horizontal natural circulation systems do not use a kettle design exchanger, but rather a 1-2 (1 shell side, 2 tube-side passes) unit, with the vaporized liquid plus liquid not vaporized circulating back to a distillation column bottoms vapor space or, for example, to a separate drum where the vapor separates and flows back to the process system and where liquid recirculates back along with make-up feed to the inlet of the horizontal shell and tube reboiler. See Figures 10-96A-C. 

Some examples of ambient air impactors include the low-pressure impactor (LPI) (10), the Battelle (II, 12), the Multi-Day (MD) (13), the Davis Rotating Unit for Monitoring (DRUM) (14, 15), the Berner Low-Pressure Impactor (BLPI) (16), and the Micro-Orifice Uniform Deposit Impactor (MOUDI) (17). Each has a different way of collecting particulate matter. Because of the small mass of aerosols, certain parameters of the design of the impactor are adjusted so that the aerosol can be analyzed with a maximum degree of sensitivity. Some of the parameters involve the flow rate at which the impactor operates the material is concentrated to a smaller area or the... 

Normal vertical knockout drums are designed for a K value of about 0.20 to 0.25. If we are installing a KO drum ahead of a reciprocating compressor—and they really hate liquids in their feed—a K value of 0.14 might be selected. If we really do not care very much about entrainment, a K value of 0.4 might be selected. An example of this would be venting waste gas to the flare from a sour-water stripper reflux 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. 

For the flow conditions of Example 18.2, design a drum with a standard efficiency stainless steel wire mesh pad. For this condition, k = 0.35, so that... 

Chemical process equipment is of two kinds custom designed and built, or proprietary off the shelf. For example, the sizes and performance of custom equipment such as distillation towers, drums, and heat exchangers are derived by the process engineer on the basis of established principles and data, although some mechanical details remain in accordance with safe practice codes and individual fabrication practices. 

For example, when we consider the design of specialty chemical, polymer, biological, electronic materials, etc. processes, the separation units are usually described by transport-limited models, rather than the thermodynamically limited models encountered in petrochemical processes (flash drums, plate distillations, plate absorbers, extractions, etc.). Thus, from a design perspective, we need to estimate vapor-liquid-solid equilibria, as well as transport coefficients. Similarly, we need to estimate reaction kinetic models for all kinds of reactors, for example, chemical, polymer, biological, and electronic materials reactors, as well as crystallization kinetics, based on the molecular structures of the components present. Furthermore, it will be necessary to estimate constitutive equations for the complex materials we will encounter in new processes. 

After the secondary reformer of steam reforming plants the gas has to be brought down from around 1000 °C to about 350 °C for the HT shift. In earlier-generation plants two boilers were usually installed in series, with a bypass around the second to control the inlet temperature for the HTS. Common practice for a long time was to use a water-tube design. A famous example is the Kellogg bayonet-tube boiler, applied in more than 100 plants. Because of size limitations two parallel units were installed. For sufficient natural water circulation these boilers needed a steam drum at a rather high elevation and a considerable number of downcomers (feed water) and risers (steam/water mixture). 

Vacuum drum filters, 319 air flow rates, 328 applications, 332 cycle design, 328 flowsketch, 326 laboratory test data, 312 minimum cake thickness, 328 operation, calculation example, 312,... 

---