Multistage Concurrent Absorption of Heavy Hydrocarbons

MgoPg/ gPgo 1- For example, as the pressure changed from 4 to 12 MPa at = 0.1 kg/m, the molar fractions increased by 1 or 2 orders of magnitude. A similar picture is observed for the other values of q. 

Consider now the multistage concurrent absorption calculations, as exemplified by the spray absorber and by absorption inside the pipeline. 

One possible design of a direct-flow spray absorber is shown schematically in Fig. 20.3. Each stage of the absorber consists of a contact chamber and a mesh separator placed in tandem. To simplify calculations, assume that the separator operates with a 100% efficiency, i.e. dry gas comes out from the contact stage. 

Gas composition at the entrance of the absorber, and composition of the fresh absorbent (straw oil) is given in Table 20.2. Fractions into which hydrocarbons Ce+ are grouped are designated by Fi. 

For the given values of p, T, and Qg, it is possible to determine the length of the contact zone, by demanding, for example, that molar concentrations at the exit differ by 1% from their corresponding equilibrium values. Using expression (20.4), we then obtain  

---

Multistage Concurrent Absorption of Heavy Hydrocarbons 645 Table 20.3 Initial composition of the gas and the absorbent (molar fraction %). 

---