CHEMICAL







Chemical Manufacturer Avoids Shutdowns by

Using Fieldbus Technology

RESULTS



� Avoided chemical reactor shutdown



� Estimated cost savings of $1.5 million in lost production



� Avoided labor and material costs associated with unplugging the

  reactor





                                                                                  The Rosemount 848T and

APPLICATION

                                                                                  3420 provided an efficient,

Monitoring reactor temperature during polymerization process

                                                                                  cost-effective solution.

CUSTOMER

A North American chemical manufacturing company

CHALLENGE

It is typical to carefully monitor the transition of a chemical reactor during

start-up with a process designed to run at constant steady state

conditions. In this case, a chemical manufacturing company was preparing

to start up one of its production trains for a particular product type. Precise

control of the operating conditions was necessary to regulate the

polymerization process to produce on-spec product.

To observe the progress of the reaction during start-up, the customer

wanted to monitor the temperature profile of the reactor's dome. Any

indication of the temperature moving outside the normal limits could

indicate that polymerization was occurring in the wrong stage of the

reaction. This could create a solid polymer plug in the reactor, which could

cause a unit shutdown. If the reactor were to plug, it could cost the

customer anywhere from two to three weeks in downtime, depending on

the severity of the plugging or polymerization. Lost production for this unit

is estimated at approximately $3000 per hour of downtime. This number

does not include the labor and material costs that would be required to

unplug the reactor.



SOLUTION

The project team first evaluated a traditional approach using individual

transmitters on 16 temperature sensors. Because of the long wire run and

high installation costs, the project was not funded. However, when the

team learned of the Rosemount 848T Eight Input temperature transmitter

and its potential wiring cost savings due to the FOUNDATIONâ„? fieldbus









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© 2006 Rosemount Inc. All rights reserved

CHEMICAL





technology, they quickly realized they had a cost-effective alternative. They

also used the Rosemount 3420 Fieldbus Interface Module because their

5-year-old TDC DCS did not have fieldbus capability, but a Modbus Serial

interface was available. The cost of the 848T/3420 solution was about 50%

of the traditional analog installation.

The instrumentation used in this application consisted of two 848Ts and

one 3420. Sixteen Type J thermocouple assemblies with magnetic pull

downs were installed at each required temperature monitoring point. The

sensor lead wires were run to a nearby 848T with each transmitter

accepting eight sensor inputs. The 848Ts are mounted in a junction box

and wired to a fieldbus terminal block. A single pair of wires is run from the

848Ts to the 3420, which is located about 650 feet away in the control

room where they are then interfaced to the DCS.

This cost effective temperature monitoring solution proved beneficial to

                                                                                   The Rosemount 848T installed.

the customer during start-up. The 848T and 3420 enabled the customer to

notice an increase in temperature on the dome of the reactor during

start-up. Upon entering the reactor, plastic buildup on the inside of the

dome was identified. Without these extra monitoring points, the problem

would not have been identified early enough to avoid a shutdown. The

customer estimated a savings of approximately $1.5 million in lost

production.



RESOURCES

Rosemount 848T

http://www.emersonprocess.com/rosemount/products/temperature/

m848t.html

Rosemount 3420

http://www.emersonprocess.com/rosemount/products/accessories/

m3420.html









FOUNDATION is a trademark of the Fieldbus Foundation.

Rosemount and the Rosemount logotype are registered trademarks of Rosemount Inc.

All other marks are the property of their respective owners.



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