She whispered in my ear
Something crazy
She said,
Spill the wine, take that pearl!

("Spill the Wine," Eric Burden and War, 1970)

Time to string all the pearls of wisdom related to the Process Variable Temperature together.

Stringing those pearls will require a quick review of:

• Local and remote temperature detecting and measuring instruments.
• PID representation of temperature-related instruments and their input/output signal nomenclature.
• How the Process Variable Temperature is detected, measured, and conveyed in real world temperature-changing equipment.

Throughout this PTOA Segment 97 questions will be posed to PTOA Readers and Students related to temperature detecting and measurement devices.

PTOA Readers and Students should take the time to independently ponder the answer to the inquiries.

However, the answers to the questions are coming up.

The questions are posed to intentionally prime the pump for learning how increased molecular movement caused by absorbing heat is converted into a temperature that can be viewed on a dial or screen in a format that can be interpreted by a human being.

 

LOCAL TIs AND THEIR USE

PTOA Readers and Students first saw the TI pictured on the left in PTOA Segment #1 entitled "How Hot is Hot?"
PTOA Readers and Students could imagine this real-life TI as the same TI used to measure the  temperature of the contents inside a real-life vessel like that one shown in the photo at the below right.

This real-life TI and vessel might be the same vessel and TIs represented as ISA symbols on the below P&ID excerpt.

The temperature indicators on the vessels are positioned to detect, measure and locally indicate the temperature of the top, middle, and bottom of the carbon beds loaded into carbon filter V-200A and V-200B.

The above P&ID excerpt was introduced in PTOA Segment #7 entitled "What Do P&IDs Have in Common with Crime Scenes?"

While reading that PTOA Segment, PTOA Readers and Students also noticed TI 2, a temperature indicator located on the process line that flows into Vessel 220.

 

P&ID LINE SYMBOLS

The below table of ISA line Symbols was introduced in PTOA Segment #14 entitled "I Just Gotta Get a Message To U."

Alert PTOA Readers and Students noticed that the connection between the carbon filter TIs 3A through 3F and carbon filters V-200A and V-200B were drawn with a thin line.

According to this ISA line symbol chart shown to the left, the line attaching the TIs to the vessels are 'minor process lines.'

 

What does it mean in the real world to have a temperature detected, measured and indicated through a 'minor process line' connection?

How does the TI detect some kind of change in molecular movement, then convert the movement into a temperature measurement and also locally display the temperature in a way human beings can understand?

 

PROCESS INDUSTRY TEMPERATURE-CHANGING EQUIPMENT
REAL AND DIAGRAMMED

PTOA Readers and Students who are reading the PTOA Segments in the intended sequential order can expertly identify the  process industry equipment shown to the left as a shell and tube heat exchanger.

Thanks to Southern Heat Exchanger Company (SHECO), PTOA Readers and Students expertly understand how a heat exchanger works to transfer heat between a hot process stream and a colder process stream.  PTOA Segment #30 entitled "I Heat Up .... I Cool Down!" featured the animated graphic.

The picture of a real world shell and tube HEx and the SHECO animated graphic could be the shell and tube heat exchanger E-1004 that is featured in the P&ID excerpt shown below.

After completing the PTOA Temperature-Changing Focus Study Area and the PTOA Heat Transfer Focus Study Area, PTOA Readers and Students can now connect all the dots between the P&ID excerpt and the real world process industry equipment.

PTOA Readers and Students now visually understand the process flows that the P&ID suggests:

• The shell side process flow enters the bottom of E-1004 and exits the top; NOTE: after exiting E-1004, the process stream temperature is detected, measured, and transmitted by TE (Temperature Element) 10045.
• The process flow destined for the tube side of E-1004 enters the graphic on the below left; Some of the tube side process flow is bypassed around the E-1004.
• The portion of tube side process flow that flows into E-1004 can be visualized flowing through the channelhead inlet on the top of E-1004 → flowing through the tube bundle → exiting the channelhead on the bottom → reuniting with the portion of process stream that had bypassed

Wow! The P&ID schematic indicates that the  the amount of tube side flow bypassed around the exchanger is determined by the shell side effluent temperature that is detected, measured, and transmitted by TE 10045!  Very interesting!

PTOA Readers and Students focussed on the components of  Temperature Control Loop 10045 in PTOA Segment #16 entitled "Ever Evolving ISA Symbols."

PTOA Readers and Students have collected many, many more pearls of wisdom regarding temperature changing process industry equipment and heat transfer since reading PTOA Segment #16.

At this juncture, PTOA Readers and Students have a much better understanding what TE 10045 is and its important role with respect to the optimal transfer of heat between a the hot and cold process streams that enter E-1004.

What kind of physical connection does the P&ID excerpt illustrate exists between the shell side outlet  process flow line and TE 10045?

What kind of signal is sent from TE 10045 to TIC 10045?

How the heck can a TE detect a change in molecular movement  and convert that movement into a into a measurement that is eventually conveyed as an electric signal to the controller TIC 10045 located in the control room?

In summary,

Those little temperature measuring devices are performing important functions and expected to yield accurate temperatures.

And now PTOA Readers and Students are ready to learn how the Process Variable Temperature is detected, measured, indicated, and transmitted.

TAKE HOME MESSAGES: The purpose of this PTOA Segment was to review many of the concepts PTOA Readers and Students understand about the Process Variable Temperature management, both in the real world of processing and as depicted on P&IDs.

Accurate detection, measurement, indication, and transmitting of the sensed process temperature depends upon the temperature measuring device.

Temperature measuring devices convert molecular movement into an indication or signal that eventually can be understood by a human being to represent a process temperature.

 

©2016 PTOA Segment 00097
PTOA Process Variable Temperature Focus Study Area
PTOA Process Industry Automation Focus Study Area

 

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