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Change Your Board

Operator to a Process

Manager With State

Based Control

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Tom Nolan

• Tom Nolan is a Senior Consultant for ProSys, a global

process control software and engineering firm

headquartered in Baton Rouge, LA. Tom joined ProSys

in April of 2013. He brings more than 24 years of state

based control experience from his tenure at Dow

Chemical. Tom has extensive experience in all aspects of

state based control.

Abstract

This presentation examines the attributes of state based

control and the value delivered to manufacturing from the

initial design through the operating life of the facility by

improving the effectiveness of operators.

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Background

Before DCS

• Smaller span of control for the operators

• Panel mounted controller and trends were visible by walking the

board

• Fewer, more strategic alarms

• Most things needed were in view and in reach

• The operator ran the plant differently depending on the state of

the process

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Background

After DCS

• Larger span of control for the operators

• Many more things to alarm and more ways to alarm them

• Only the trends and graphics called up are visible

• Many more, probably less well thought out alarms

• Need to work through the HMI to get to what you need to see

and change

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Background

Not Utilizing DCS Capabilities

• Systems take advantage of bringing in tremendous amounts of

data and alarming it in many different ways

• Not maximizing the DCS’ ability to enable alarms and drive

outputs based on state

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Background

Control systems are, for the most part, configured for

optimal performance in the running state.

• Makes sense in terms of time

• Hopefully spend most of the time in the running state

In terms of risk, it is not able to deliver.

• 70% of incidences occur in start up or shutdown

• Everyone has the least amount of experience with these states

• The control system is either not helping or is a hindrance

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What is a State?

“It is a definable operating state in which the control system

needs to take action to achieve the desired objective for

that operating state.”

- Dustin Beebe, President/CEO of ProSys, Baton Rouge, LA

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What is a State?

States

• Processes move through definable states

as they operate

• States range from being down for

maintenance to running in steady state or

cycling through a batch.

• States can include:

• Filling, Establishing Fractionation, Total

Reflux, Recycle, Running, Normal

Shutdown, Emergency Shutdown

• State based control changes with the state

of the process

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State Based Control

There are two types of state based control:

• Inferred State – Using process measurements to infer what state

the process is in

• Driven State – Using the DCS to drive the outputs to put the

process in the desired state

• This is the emphasis of this presentation

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Why State Based Control?

Processes don’t operate in one state.

• What is normal and abnormal changes with the state

• Alarms need to inform operators about what is abnormal and

requires operator action to prevent undesirable consequences

• Control mode needs change with state

• Controller tuning may need to change with state

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Why State Based Control?

Processes don’t operate in one state.

• A control system configured for only one state can not perform

optimally for the other states

• A low coil outlet temperature alarm is important in a running state

• It is extraneous information when the plant is down for maintenance

• Crowding out the things that are important

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Beyond a Safety Function to a Safe

State: A Coordinated Safety Response

• Single loop Safety Instrumented Functions do a good job of reducing

risk at the designed Safety Integrity Level to bring the plant to a safe

state in that the designed for scenario will not occur.

• For instance, if the reactor has a high pressure, close the steam valve

• Now that the steam valve has closed on the reactor, there is a lot going on and a

lot for the operator to deal with in the reactor unit and upstream and downstream

units

• State based control brings the reactor to a predetermined safe

control state.

• The DCS drives all of the output immediately to where it needs to go

• The reactor unit communicates its status to up and down stream units so that

they know how to respond automatically as well

• Moving to and staying at their highest state of readiness for when the reactor

comes back on line

• There can be multiple safe states that the DCS drives the process to

depending on the scenario.

• The safe state can be used for any number of different scenarios.

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Beyond a Safety Function to a Safe

State: A Coordinated Safety Response

The designed for scenario does

not occur. A lot else does:

• An alarm shower

• Up and down stream equip

effected

• Loops are put in manual

• Increased risk

• Down time

• Bypasses may need to be set

for start up

The designed for scenario does

not occur.

• The plant stays at it’s highest

state of readiness to minimize

process interruption

• The operator is in a heads up

mode monitoring the process, not

trying to operate controllers in

manual

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High Rx

Pressure

Normal control

scheme

State Based Control(Coordinated Safety

Response)

SIS closes steam valve

Operator deals with the

ramifications manually

Rx moves to a safe stateClose steam valve

Stop feeds

Full cooling

Reduce pressure

Alarm dynamically

managed

enabling proper operator

action

Move the back end to

recycle state ready for

when the reactor comes

back up

Cost of Not Automating

State based control gets at the root causes of unscheduled

shutdowns.

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Cost of Not Automating

State based control hits the heavy hitter in cost of incidents.

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Peripheral Cost of Incidents

Deepwater Horizon Oil Spill – BP – 2010

• U.S. Environmental Protection Agency (EPA) fines of $15 million

• Occupational Safety and Health Administration (OSHA) fine of

$51 million for a single facility

• Escrow account of $20 billion to the U.S. Government to cover

potential oil spill costs

• ~45% decrease in stock value in the months following the

incident

• Temporary reduction in sales at BP stations by as much as 40%

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Peripheral Cost of Incidents

Bhopal Disaster – Union Carbide – 1984

• ~15,000 incident related deaths

• ~550,000 incident related injuries

• ~$500 million in legal decisions and voluntary funding of support

facilities (hospitals, research facilities, etc.)

• ~30% decrease in stock value in the months following the

incident

• Eventual devaluing and sale of consumer products division

• Divesting of assets

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Reduction in Unplanned Events

Facilities grouped by

alarm loading and level of

automation

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Unplanned event data has

a strong correlation to the

quadrant a plant is in

Automation

Ala

rms

Reduction in Unplanned Events

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Performance• Consistent

• Repeatable

• Transferable

Aging Workforce and Knowledge Loss

• Within 5 years, 20% of

the workforce could

retire

• The Social Security

Administration

estimated 10,000 per

day

• Will create skills gaps

and large burden for

training

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The New Work Force

• More mobile younger workforce

• Not looking for or expecting 30 yrs and a pension

• According to the Bureau of Labor Statistics, the average

worker stays at each job for 4.4 years

• Most millennials expect that they will change jobs in less

than every three years

• Training cost and techniques have to change to keep up

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Knowledge Capture and Transfer With

State Based Control

• Operational process knowledge is captured and

leveraged in the design process

• Keeps the knowledge of the best operator on the board

at all times and reduces training demands

• The knowledge, once captured, can also be leveraged

through the corporation, improving the return on the

initial investment

• All of the operators on the board can manage the

process at a higher level based on the experience and

collective knowledge of everyone running the plant

• The plant to become smarter over time

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Benefits of State Based Control

• Increased productivity

• Higher asset utilization

• Enforces proper start up and shutdown sequencing improving

asset utilization

• Minimizes environmental incidents and violations

• More efficient use of resources

• Frees operators from mundane tasks

• Allows the operator to manage the process in a heads up

prioritized manner

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Benefits of State Based Control

• Reduces operator errors

• Less outputs to be managed in manual

• Automated response and recovery from abnormal

situations

• Provides a mechanism to capture and transfer

knowledge

• Best operator is always on the board

• Allows for the standardization and proliferation of best practices

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Proven Performance in Start Up

Performance

State based control has implemented which enabled start

up in one third of the time of non-state based control.

• This is consistent repeatable performance from all of the

operating staff

• Plant is also able to change product specification more quickly to

meet market demand

• The state based control is using the proper procedures on the

equipment to not unduly stress it for start up and shutdown,

therefore increasing asset utilization

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Degradation Scenarios

Managing Abnormal Situations

• Provides the ability to detect and optimize the automated

response to process upsets

• Keeps the plant safer in upset conditions

• Keeps the plant at the highest state of readiness to return to

normal operation as soon as possible

• Minimizes lost production and equipment damage

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Proven Performance in Handling

Upset Conditions

State based control has been implemented in a refinery that

handles upset conditions.

• Before state based control, the upset would cause a trip and

subsequent restart of the facility taking 8 to 12 hours

• With state based control, there is only a 15 to 45 minute process

disturbance with no trip

• This eliminates a shutdown and start up where 70% of incidences

occur

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State Based Control

Balancing Operator and Automatic Action

• Digital control systems provide information quickly

• Creates information overload that makes it more difficult to

operate the plant

• State based control uses available information to turn this

situation around

• Manages the alarms for required operator action

• Manages the outputs

• Drives the process to a safe state

• Returns the process to normal as quickly as possible

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Justification

Alarm and Instrumentation Justification

• Dynamic alarm management and alarm rationalization can be

designed in from the beginning

• New plant, no experience running it and overwhelmed by alarms is a

bad situation

• Instrument justification includes alarm rationalization and desired

level of automation

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Conclusion

• State based control is a viable option to improve the design process

through the use of standard reusable architecture and instrument

and alarm justification.

• State based control maximizes the investment in the DCS by

capturing knowledge in the form of operating discipline that can be

leveraged with greatly reduced training costs in a dynamic

workforce.

• Safety and operability are enhanced through the uses of safe states

in units and the communication between units to optimize the

response to degradation scenarios.

• Operators are in a position to manage the process through state

changes while having their heads up to see the big picture - avoiding

problems and optimizing performance.

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