Optical method for determining fouling of crude and heavy fuels

A non-transitory computer-readable medium product having stored thereon instructions that, when executed by at least one processor, perform a method, the method comprising:

• extending a probe from a retracted position to an extended position within a flowing fluid;
• detecting formation of a second phase in a hydrocarbon mixture with a first phase using data from a probe positioned in a flowing fluid comprising the hydrocarbon mixture and a known property of the hydrocarbon mixture, wherein the probe is responsive to an electromagnetic signal that has passed through a portion of the mixture across a gap in the probe, the portion of the mixture having entered the probe through the gap.

A method for detecting phase formation in a hydrocarbon mixture using a probe comprising a housing, comprising:

• installing the probe for operation in a flowing fluid comprising the hydrocarbon mixture such that an exterior of the housing is immersed in the flowing fluid, the probe configured to be retracted while not in operation;
• and
• detecting, in situ, formation of a second phase in the hydrocarbon mixture with a first phase by comparing a change in a parameter of interest of the hydrocarbon mixture, wherein the parameter of interest is estimated by the probe and the change exceeds a selected threshold.

A method for detecting phase formation in a hydrocarbon mixture using a probe comprising a housing, comprising:

• detecting, in situ, formation of a second phase in the hydrocarbon mixture with a first phase using data from the probe and a known property of the hydrocarbon mixture, wherein the probe is responsive to an electromagnetic signal that has passed through a portion of the mixture across a gap in the probe, wherein the gap is configured to draw the portion of the mixture into the gap through capillary action.