1. Blending process

2. The desired RVP of a gasoline is obtained by blending n-butane with naphtha. The amount of n-butane required to give the needed RVP is calculated by:

5. Vapor pressure blending indices (VPBI) have been compiled as a function of the RVP of the blending streams
Reid vapor pressure of the blend is closely approximated by the sum of all the products of the volume fraction (v) times the VPBI for each component. In equation form:
In the case where the volume of the butane to be blended for a given RVP is desired:

6. Although this differs slightly from the result obtained in Example 1, they agree well within the limits required for normal refinery operation.

9. Blending of viscosities may be calculated conveniently by using viscosity factors. In equation form:
The pour point index of the blend is the sum of the products of the volume fraction times the pour point blending index (PPBI) for each component, or

10. The requirements are to produce a gasoline with;
Reid vapor pressures of 10.2 psi (70.3 kPa). VPBI of 18.2 (see equation);
Pool octane number (PON) needed is 89.
The available basic blending stocks are then selected for blending
After selecting the stocks, the quantity of n-butane required to give the desired vapor pressure is calculated first because the n-butane contributes significantly to the octane of the finished product.
The gasoline blending streams available from the various units are:

11. Octane number : Is a measure of a gasoline’s resistance to knock in a cylinder of a pertol engine.
The higher octane number, the higher the resistance to knock, the higher is the efficiency of the fuel to produce work.
RON (Research Octane Number) is determined in a single cylinder variable compression ratio engine that operates at 600 rpm with a 65.6 ºC inlet air temperature at standard barometric pressure.
MON (Motor Octane Number) is determined at engine speed of 900 rpm and ºC inlet air temperature.
Usually RON> MON
RON-MON=sensitivity of the gasoline

12. The quantity of n-butane required (W) to give the desired vapor pressure (10.2psi or VPBI=18.2) is calculated first

14. METHYL TERTIARY BUTYL ETHER (MTBE)
Methyl tertiary butyl ether (MTBE) is produced by the reaction of isobutene with methanol.
Its main use is as a gasoline blending component, due to its high octane level (RON = 115—135, MON = ).
Any hydrocarbon stream containing isobutene can be used for the production of MTBE.