Sizing vapor/liquid separator

Scheiman, A.D. Size Vapor-Liquid Separators Quicker by Nomograph, Hydrocarbon Processing and Petroleum Refiner, Oct. 1963, p. 165. 

IV.2.2 Sizing vapor/liquid separator with mist eliminator [2]... 

For rough sizing check of vapor/liquid separators and accumulators, see the Fluor method in Chapter 8, Separators/Accumulators—Vapor/Liquid calculation method. 

Vapor-liquid separators (drums) are used to separate a liquid from a vapor-liquid stream with a minimum of liquid carryover. The separator size is determined by the vapor velocity which depends on the entrainment method used. The working equation is ... 

The heating surface usually determines the evaporator cost and the vapor head the space requirements. The vapor—liquid separator must have enough horizontal plan area to allow the bulk of the initial entrainment to settle back against the rising flow of vapor and enough height to smooth out variations in vapor velocity and to prevent splashing directly into the vapor outlet. Separators are usually sized on the basis of the Souders-Brown expression ... 

Vapor-liquid separators often perform two functions. Their primary task is to separate the vapor phase from the liquid phase but they may also provide surge capacity. They must be sized to provide a low velocity and thus separate the liquid from the vapor. 

Evans (1980) proposed a stepwise design procedure for sizing empty vertical and horizontal vapor-liquid separators. The steps are outlined as follows ... 

The following steps are used to size a vertical drum. Step 1. Calculate the vapor-liquid separation factor. 

Florizontal vessels are used for substantial vapor-liquid separation where the liquid holdup space must be large. Maximum vapor velocity and minimum vapor space are determined as in the vertical drum, except that for horizontal separators is generally set at 1.25K. The following steps are carried out in sizing horizontal separators. 

Control system. For subsequent selection and sizing of pumps and compressors, we need to map out the number and location of the control valves. Since the number of control valves is related to the number of control degrees of freedom, identify the control degrees of freedom. For example, a typical hydrodealkyllation process with a reactor, furnace, vapor-liquid separator, recycle compressor, two heat exchangers, and three distillation columns has 23 control degrees of freedom (Luyben et al., 1997). This requires 23 control valves whose location affects the rest of the design and the safety and hazards (see Section 16.7). 

Nomographs can be used to quickly size vertical knockout drums, oil separator drums, compressor dry drums, flash drums or any other vertical vapor-liquid separator. 

A vapor-liquid separator is to be sized for a true vapor flow of 1.5 cfs. Vapor density is 0.65 pounds per cubic foot. Liquid density is 63 pounds per cubic foot. Use = 0.2 for this service. What diameter drum is required ... 

Scheiman, A.D. Use Nomographs to Size Horizontal Vapor-Liquid Separators. Hydrocarbon Processing Petroleum Refiner, 1964, p. 155. 

Vapor/Liquid Separator Sizing Method Uquid Entrainment Method... 

This part, on applications, covers the following unit operations 8. Evaporation 9. Drying of Process Materials 10. Stage and Continuous Gas-Liquid Separation Processes (humidification, absorption) 11. Vapor-Liquid Separation Processes (distillation) 12. Liquid—Liquid and Fluid-Solid Separation Processes (adsorption, ion exchange, extraction, leaching, crystallization) 13. Membrane Separation Processes (dialysis, gas separation, reverse osmosis, ultrafiltration) 14. Mechanical-Physical Separation Processes (filtration, settling, centrifugal separation, mechanical size reduction). 

We work in a stagnant industry. It s true that vapor-liquid separation can be greatly improved by the use of vertical vortex tubes, which are a relatively new development. Yet most vapor-liquid separators are still empty vessels that depend on gravity settling and are sized in accordance with Stokes Law. 

IV.2.1 a Sizing vertical gravity settling vapor/liquid separator... 

Onoe allowable velocity (va) is known, vapor/liquid separator can be sized as follows ... 

---