Patent ID: 8748677

Claim:
A method for making fuel enriched by mixed pentanes comprising the steps: a) providing a fuel blending unit characterized by: i) a first enclosed conduit transmitting a fuel stream, and ii) a second enclosed conduit transmitting an additive stream having a positive vapor pressure blend value on the fuel stream, wherein the additive stream comprises n-pentane and isopentane at a ratio of from 1:4 to 4:1, and iii) an outlet in the second enclosed conduit forming a fluid connection with an inlet in the first enclosed conduit, b) providing: i) a volatility for the additive stream (the “additive stream volatility”), ii) a flow rate for the fuel stream (the “fuel stream flow rate”), iii) an octane value for the fuel stream (the “fuel stream octane value”), and iv) a maximum blended volatility for the fuel stream (the “maximum blended volatility”), c) measuring the fuel stream for its actual volatility (the “fuel stream volatility”), upstream or downstream of the fluid connection, d) calculating a rate (the “additive stream flow rate”) at which the additive stream can be added to the fuel stream so as not to exceed the maximum blended volatility, wherein the calculating is based upon: i) the fuel stream volatility, ii) the additive stream volatility, and iii) the fuel stream flow rate, and e) adding the additive stream to the fuel stream at the additive stream flow rate at the fluid connection to make pentane enriched fuel having a final octane value, wherein said ratio of isopentane to n-pentane in said mixed pentane stream is adequate to overcome the depression in octane induced by said n-pentane, such that the n-pentane does not cause the final octane value to drop below the fuel stream octane value.