Process fluid device temperature control

• US 20070068922A1
• Filed: 09/29/2005
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Orth, Kelly, Westfield, Brian
• Granted Patent: US 7,679,033 B2
• Time in Patent Office: Days
• US Class Current: 219/447.100
• CPC Class Codes: G01L 19/04 Means for compensating for effects of changes of temperature , i.e. other than electric compensation
• CPC Class Codes: G05B 19/0423 Input/output
• CPC Class Codes: G05B 2219/25428 Field device
• CPC Class Codes: G05B 2219/31121 Fielddevice, field controller, interface connected to fieldbus
• CPC Class Codes: G05D 23/19 characterised by the use of electric means G05D23/1393 takes precedence

Abstract

A field device system for use in an industrial process includes a field device configured to couple to the industrial process and monitor or control the industrial process. The field device provides a temperature control signal output related to a temperature of the field device. A heater coupled to the field device heats the field device in response to the temperature control signal.

Claims

1. A field device system for use in an industrial process comprising:

a field device configured to couple to the industrial process and monitor or control the industrial process, the field device including a temperature control signal output related to a temperature of the field device; and

a heater coupled to the field device and configured to heat the field device in response to the temperature control signal.

2. A field device system of claim 1 wherein the field device comprises a transmitter configured to measure a process variable of the process and provide an output on a two-wire process control loop related to the measured process variable.

3. The apparatus of claim 1 wherein the field device includes an internal temperature sensor and the temperature control signal output is related to the temperature of the temperature sensor.

4. The apparatus of claim 1 wherein the temperature control signal output comprises a digital signal.

5. The apparatus of claim 1 wherein the temperature control signal output is provided on a two-wire process control loop coupled to the field device and to the heater.

6. The apparatus of claim 5 wherein the electrical connection provides isolation of DC signals.

7. The apparatus of claim 1 wherein the field device is configured to couple to a high purity vacuum process.

8. The apparatus of claim 1 wherein the heater couples to an external power supply.

9. The apparatus of claim 1 wherein the heater includes a heater element and wherein a relationship between the temperature control signal output and heat from the heater element is programmable.

10. The apparatus of claim 9 wherein the relationship between the temperature control signal output and heat from the heater element is programmed through a local interface.

11. The apparatus of claim 9 wherein the relationship between the temperature control signal output and heat from the heater element is programmed through digital signals received in accordance with the HART®

communications protocol.

12. The apparatus of claim 1 wherein the field device includes a pressure sensor configured to sense a pressure of the industrial process.

13. The apparatus of claim 12 wherein the pressure sensor includes a temperature sensor and the temperature control signal output is related to the temperature of the temperature sensor.

14. The apparatus of claim 1 wherein the heater includes a heater element and a controller configured to implement a control algorithm and responsively control heat from the heater element as a function of the temperature control signal output.

15. The apparatus of claim 1 wherein the heater includes thermal overload protection.

16. The apparatus of claim 1 wherein the heater includes a local output configured to provide an indication of heater status.

17. The apparatus of claim 1 wherein the heater is configured to diagnose impending failure of a heater element of the heater.

18. A method reducing accumulation of process material on a field device in an industrial process, comprising:

sensing an internal temperature of the field device;

providing a temperature control signal output related to the sensed temperature;

coupling the temperature control signal output to a heater which is thermally coupled to the field device; and

responsively heating the field device with the heater as a function upon the temperature control signal output.

19. The method of claim 18 including measuring temperature of the field device with an internal temperature sensor and the temperature control signal output is related to temperature of the temperature sensor.

20. The method of claim 18 wherein the temperature control signal output comprises a digital signal.

21. The method of claim 18 wherein the temperature control signal output is provided on a two-wire process control loop coupled to the field device and to the heater.

22. The method of claim 18 wherein the heater includes a heater element and wherein a relationship between the temperature control signal output and heat from the heater element is programmable.

23. The method of claim 18 including diagnosing impending failure of a heater element of the heater.

24. The method of claim 18 including controlling heating of the field device to prevent freezing of the device.