FIELD

Embodiments of the present disclosure relate to industrial process temperature transmitters and, more specifically, to compensating temperature measurements performed by the temperature transmitter for a response time of the temperature measurement.

BACKGROUND

Industrial processes are used in the manufacturing and transport of many types of materials. In such systems, it is often required to measure different parameters within the process. One such parameter is a temperature of the process medium.

Industrial process temperature transmitters typically measure the temperature of the process medium using a temperature sensor and communicate the measured temperature to a desired location, such as a control room. Such temperature transmitters typically isolate the temperature sensor from the process medium to protect the temperature sensor and associated electronics from process conditions that may damage the sensor, and/or adversely affect the temperature measurement.

Some temperature transmitters house the temperature sensor within a thermowell. The temperature sensor is installed in the thermowell through an open end. A sealed end of the thermowell is inserted into the process medium. This allows the temperature sensor to measure the temperature of the process medium through the thermowell without being directly exposed to the process medium. Thus, the temperature sensor may be inserted into the process medium while providing protection from harsh conditions that could damage the sensor.

Other temperature transmitters measure the temperature of the process medium while avoiding any intrusion on the process. Such non-intrusive temperature transmitters typically position a temperature sensor in contact with the exterior surface of a process vessel wall containing the process medium, such as the exterior surface of a pipe containing the process medium. The temperature sensor measures the temperature of the process medium through the process vessel wall.

Temperature transmitters experience a delay in the detection of a change in the temperature of the process medium that is caused, at least in part, to the need to communicate the temperature through the wall of the thermowell or the wall of the process vessel. For some applications, such as those where temperature measurement timing is critical for process management, such a delay in the temperature measurement may be unacceptable.

SUMMARY

Embodiments of the present disclosure relate to industrial process temperature transmitters for measuring a temperature of a process medium, and methods for measuring a temperature of a process medium using an industrial process temperature transmitter. Some embodiments of the temperature transmitter include a temperature sensing unit, a compensation circuit, an output circuit and a housing. The temperature sensing unit includes a process temperature sensor that is separated from the process medium by an isolation wall, and a secondary temperature sensor that is configured to produce a secondary temperature signal based on a sensed temperature. The temperature sensing unit is configured to produce a temperature signal that is indicative of the temperature of the process medium based on a process temperature signal output from the process temperature sensor and the secondary temperature signal during a temperature measurement. The compensation circuit is configured to compensate the temperature signal for a response time of the temperature measurement to a change in the temperature of the process medium, and output a compensated temperature signal. The output circuit is configured to produce a temperature output as a function of the compensated temperature signal corresponding to the temperature of the process medium. The housing is attached to an exterior of the process vessel and contains the secondary temperature sensor.

In some embodiments of the method, a temperature measurement of a temperature of a process medium is performed using a temperature sensing unit including sensing the temperature of the process medium through an isolation wall using a process temperature sensor comprising a thermistor, and sensing a temperature of a terminal block of the transmitter using a secondary temperature sensor. A temperature signal is produced in response to the temperature measurement by processing a process temperature signal from the process temperature sensor and a secondary temperature signal from the secondary temperature sensor. The temperature signal is compensated for a response time of the temperature measurement and a compensated temperature signal is generated, in which the response time of the temperature measurement is reduced or eliminated, using a compensation circuit. A temperature output is produced as a function of the compensated temperature signal using an output circuit of the transmitter.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the Background.

