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Carbon Capture and Storage: Why and How?

Carbon Capture and Storage: Why and How?

Carbon (CO 2 ) capture and storage (CCS) i...

Can Valves Mitigate Flooding from Severe Weather Events

Can Valves Mitigate Flooding from Severe Weather Events

Hurricanes Harvey and Irma have certainl...

Machine Learning: A Brave New World

Machine Learning: A Brave New World

Whether you embrace it as a way to more ...

The Road to Valve Knowledge

The Road to Valve Knowledge

Valve expertise is a journey, not a dest...

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Industry Headlines

Permian ‘Super Basin’ Holds Trillions in Untapped Oil

Monday, 25 September 2017  |  Chris Guy

Energy researchers at IHS Markit have completed the first, three-year phase of a massive Permian Basin research project that models and interprets the...

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Industry Headlines

Flowserve Appoints Lee Eckert as CFO

8 HOURS AGO

Flowserve has named Lee Eckert as senior vice president and chief financial officer (CFO), effective October 9, 2017. Eckert joins Flowserve from CHC Group LLC., a global commercial helicopter service provider to the offshore oil and gas industry, where he served as senior vice president and CFO since...

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Velan Announces New Sales Structure

4 DAYS AGO

Velan is re-designing its sales structure to be better aligned with customers’ market approach. This change is intended to focus Velan’s resources on maximizing impact and competitiveness in today’s challenging economy.

Paul Dion has been appointed as vice-president of sales, process ...

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Permian ‘Super Basin’ Holds Trillions in Untapped Oil

2 HOURS AGO

Energy researchers at IHS Markit have completed the first, three-year phase of a massive Permian Basin research project that models and interprets the giant basin’s key geologic characteristics to better estimate its remaining hydrocarbon potential, and initial results indicate the giant basin ...

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DowDuPont Opens New Ethylene and Plastics Plant in Texas

4 HOURS AGO

DowDuPont Materials Science announced the startup of its new integrated world-scale ethylene production facility and its new ELITE enhanced polyethylene production facility, both in Freeport, TX. Both units will continue to ramp up through the third quarter and are expected to reach full rates in the ...

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U.S. Manufacturers Seeking More Renewable Energy

4 DAYS AGO

A new report from David Gardiner and Associates finds that 83% of the largest manufacturing companies with a U.S. footprint have established greenhouse gas reduction targets and 25% of manufacturers have established renewable energy targets. The analysis also finds that enabling access to renewable en...

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Harvey Caused Steep Drop in U.S. Industrial Output

7 DAYS AGO

Industrial production declined 0.9% in August following six consecutive monthly gains. Hurricane Harvey is estimated to have reduced the rate of change in total output by roughly 0.75%. The index for manufacturing decreased 0.3%; storm-related effects appear to have reduced the rate of change in facto...

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A Case for Mechanical Temperature Control

vmwnt12_beyond_valves_fig1Instrument, mechanical or project engineers may see a multitude of temperature applications cross their desks. Their immediate reaction might be to employ a temperature control loop. But could a mechanical, self-operated temperature regulator be a better solution for the valve application?

When approaching a temperature control application, the engineer usually considers:

  • The degree of accuracy needed
  • Whether the application requires feedback (Are limit switches/output signals used?)
  • Whether the application needs to be controlled through a DCS, PLC or other type of controller
  • The budget for the application.

The answer to whether a mechanical temperature regulator might be a cost-effective and reliable solution for the application depends on those considerations.

In almost any process facility, a variety of temperature control applications can be found. As with any controlled variable, both the accuracy and criticality of those applications can vary widely. Often, non-critical temperature applications become instrumented control loops even when a self-operated or mechanical regulator could provide the desired accuracy along with a substantial cost savings.


WHAT’S CONSIDERED

vmwnt12_beyond_valves_fig1Figure 1. Temperature regulatorA typical temperature control loop ­(Figure 1) requires:

  • a temperature sensor
  • wiring and conduit
  • connection to a controlling device
  • a control valve (and sometimes a positioner and/or I/P converter, and an air-filter regulator)
  • plant air

A self-contained temperature regulator requires no power, no air supply or other expensive compo­nents to operate. Representative costs based on a 1-inch line size would be:

  • Temperature transmitter: $300-1,000
  • Temperature controller: $400-1,000
  • Control valve and actuator: $1,500-3,000
  • I/P converter: $200-350
  • Air set regulator: $100-150
  • Positioner: $500-2,000
  • Control loop total: $3,000-7,500
  • Temperature regulator: $500-2,500

Although designs may vary from manufacturer to manufacturer, most temperature regulators operate on the same principle. A premeasured amount of “fill” is drawn into the thermal system filling the upper diaphragm chamber, the capillary tube and most of the bulb. As the controlled temperature increases, the fill in the sensing bulb begins to vaporize and creates pressure on the sealed system. This pressure drives the valve stem, closing direct-acting valves or opening reverse-acting valves. By using different fill fluids, many different temperature control ranges can be offered for both cooling and heating applications—temperature ranges are readily available from -20° F (-29° C) to 500° F (260° C).

Applications for which these devices might be ideal include tank farms, large heat exchangers, heat exchangers with slow temperature changes, area heating/cooling (warehouse/maintenance shops) and steam tracing.

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