Systems and methods for detecting coking in a wash bed of a vacuum pipe still with a sensing cable including an optical fiber sensor array aligned with a heating element disposed in the vessel. An optical signal interrogator is configured to measure a first temperature profile at a plurality of sensor locations to determine a flow distribution. An excitation source is configured to propagate at least one heat pulse through the heating element and the optical signal interrogator is configured to measure a second temperature profile corresponding to the heat pulse at the sensor locations. A control unit is configured to detect coking by determining one or more properties of the media exposed to the sensing cable at each of the plurality of sensor locations based on the second temperature profile corresponding thereto.

A fluid sensor cable assembly and method uses one or more conductive bodies extending along an elongated core body for conducting a heating current to heat the cable assembly. The one or more conductive bodies also are configured to conduct an interrogation signal and to conduct reflections of the interrogation signal. One or more optical fibers extend along the length of the core body and include temperature sensitive elements at different locations along the length of the core body. The temperature sensitive elements measure heat flux out of the cable assembly at the different locations subsequent to heating the cable assembly and communicate the heat flux to a computer acquisition system.

A sensor for measuring flow speed of a fluid, comprising: a light-absorbing optical fiber having a fiber Bragg grating inscribed in the fiber; wherein light is emitted into the light-absorbing optical fiber to heat the optical fiber and the fiber Bragg grating, and when the fluid passes over the sensor, the flow speed of the fluid is determined by the rate of heat loss from the sensor, and the temperature of the sensor is determined from the wavelength shift of the central wavelength of the fiber Bragg grating.

A fluid measurement system and method for determining distributed measurement of a fluid type and a fluid velocity in a wellbore, pipeline or other conduit in which fluid is moving. Measurement is made by immersing one or more cables having sequential sampling sections in the fluid and monitoring a cooling effect across a cable on the sampling sections and the response to injection of a high frequency pulse each sampling section. A probabilistic model is then used to determine the distributed velocity and fluid types along the conduit.

The present disclosure provides a method for measuring flow velocity distribution of groundwater using distributed optical fiber with active heating, comprising: setting and optimizing field test parameters; conducting a background temperature monitoring test; performing a line-source active heating distributed temperature measurement test, including conducting multiple rounds of heating tests; denoising the obtained thermal plume attenuation signal data of the groundwater; and fitting the groundwater velocity-depth curve in the borehole by monitoring and analyzing the temperature difference signal between the internal temperature and the external temperature of the composite heating optical cable in a single depth section of the borehole, thereby obtaining a distributed groundwater velocity data set. The method of the present disclosure solves the problem that the existing groundwater flow velocity measurement technology cannot simultaneously conduct continuous and distributed measurements, improves the efficiency of groundwater velocity measurement, and it can avoid groundwater contamination during the measurement process.

A system for determining at least one calculated process parameter of a fluid in a pipe includes a data interface receiving nominal process parameters, which relate to nominal parameters of a process that relates to the fluid in the pipe; an invasive temperature sensor that determines a fluid temperature; a reference temperature sensor disposed outside of the pipe for determining a reference temperature; a surface temperature sensor disposed at a surface of the pipe for determining a surface temperature; a process model that determines a process parameter by using the reference temperature, the surface temperature, the received nominal process parameters, and the determined fluid temperature.

The present disclosure provides a method for measuring flow velocity distribution of groundwater using distributed optical fiber with active heating, comprising: setting and optimizing field test parameters; conducting a background temperature monitoring test; performing a line-source active heating distributed temperature measurement test, including conducting multiple rounds of heating tests; denoising the obtained thermal plume attenuation signal data of the groundwater; and fitting the groundwater velocity-depth curve in the borehole by monitoring and analyzing the temperature difference signal between the internal temperature and the external temperature of the composite heating optical cable in a single depth section of the borehole, thereby obtaining a distributed groundwater velocity data set. The method of the present disclosure solves the problem that the existing groundwater flow velocity measurement technology cannot simultaneously conduct continuous and distributed measurements, improves the efficiency of groundwater velocity measurement, and it can avoid groundwater contamination during the measurement process.