Methods for reducing transmix production on petroleum pipelines

1. An automated method for reducing transmix production on a pipeline comprising:

a) providing a flow of hydrocarbon in a transmission pipe comprising first and second hydrocarbon subtypes in sequence separated by transmix;

b) providing a transmix pipe in fluid communication with the transmission pipe separated from the transmission pipe by a transmix diverter under the control of a central processing unit;

c) repeatedly analyzing the flow for one or more physical property measurements;

d) comparing, in the central processing unit, one of the physical property measurements to a first subtype cut-point, and diverting the flow to a transmix pipe when the physical property measurement reaches the first subtype cut-point; and

e) resuming the flow through the transmission pipe when one of the physical property measurements reaches a second subtype cut-point.

2. The method of claim 1 , further comprising:

a) providing a second cut-point for the first subtype for a different physical property than the first cut-point;

b) providing a second cut-point for the second subtype for a different physical property than the first cut-point;

c) diverting the flow to a transmix pipe when the flow reaches the first or second cut-point of the first subtype; and

d) resuming the flow through the transmission pipe when the flow reaches the first and second cut-points of the second subtype.

3. The method of claim 1 , wherein the flow of hydrocarbon further comprises a third subtype in sequence, further comprising:

a) providing a first cut-point for the third subtype;

b) analyzing the flow for physical property measurements of the first cut-point of the second subtype and the first cut-point of the third subtype;

c) diverting the flow to the transmix pipe when a physical property measurement reaches the first cut-point of the second subtype; and

d) resuming the flow through the transmission pipe when the measurements reach the third subtype first cut-point.

4. The method of claim 1 wherein the flow comprises three or more hydrocarbon subtypes selected from conventional gasoline, reformulated gasoline, diesel fuel, ultra-low sulfur diesel, biodiesel fuel, aviation turbine fuel, heating oil, kerosene, reformulated blendstock for oxygenate blending, premium blendstock for oxygenate blending, conventional blendstock for oxygenate blending, subgrade gasoline, diluent, propane, pentane and butane.

5. The method of claim 1 wherein the first subtype is a high sulfur subtype and the second subtype is a low sulfur subtype, and the second subtype first cut-point comprises a sulfur content value.

6. The method of claim 5 , wherein the first subtype comprises aviation turbine fuel and the second subtype comprises diesel fuel.

7. The method of claim 1 wherein the first subtype is a low sulfur subtype and the second subtype is a high sulfur subtype, and the first subtype first cut-point is a sulfur content value.

8. The method of claim 7 wherein the first subtype comprises diesel fuel and the second subtype comprises aviation turbine fuel.

9. The method of claim 1 wherein the cut-points are physical property values selected from sulfur content, specific gravity, haze and flashpoint.

10. The method of claim 1 wherein:

a) physical properties are measured for aviation turbine fuels according to ASTM D1655-15d in effect on Jun. 1, 2016;

b) physical properties are measured for diesel fuels according to ASTM D975-15c in effect on Jun. 1, 2016.

11. The method of claim 1 wherein the flow is analyzed for the first cut-point of the first subtype at a frequency greater than once every 30 seconds.

12. The method of claim 1 wherein the flow of hydrocarbon is analyzed by:

a) withdrawing a sample of the flow of hydrocarbon from the transmission pipe;

b) transmitting the sample to an analyzing unit; and

c) either returning the sample to the transmission pipe, or transmitting the sample to a storage unit.

13. The method of claim 1 , wherein reaching a cut-point occurs when a physical property corresponding to the cut-point is greater than or equal to the cut-point when the cut-point defines a ceiling.

14. The method of claim 1 , wherein reaching a cut-point occurs when a physical property corresponding to the cut-point is less than or equal to the cut-point when the cut-point defines a floor.

15. The method of claim 1 , wherein reaching a cut-point occurs when two or more consecutive analyses of the flow yield a physical property measurement greater than or equal to the cut-point when the cut-point defines a ceiling, and a physical property measurement less than or equal to the cut-point when the cut-point defines a floor.