Inherently Safer Technology

Inherently Safer Technology

The Use ofInherently Safer Technology


Objectives• Demonstrate reasons for

implementation of inherently safer technology

• Provide examples of applications • Discuss how inherently safer

technology fits into overall Process Risk management

• Discuss key learnings from experience


Philosophy

“The essence of the inherently saferapproach to plant design is the

avoidance of hazards rather thantheir control by added-on

protective equipment.”

Trevor Kletz“Plant Design for Safety –

A User-friendly Approach,” 1991


Q. Why embracing the use of inherently safer technology?

A1. It is the right thing to do for our employees, contractors, communities.

A2. It is good for business.


A Strategy for Inherent Safety• Intensification

Using smaller quantities of hazardous substances

• SubstitutionReplacing a material with a less hazardous substance

• AttenuationUsing less hazardous conditions or less hazardous form of material

• Limitation of EffectsDesigning to minimize impact of release of material or energy

• Simplification and Error ToleranceDesigning to eliminate or tolerate operating errors.


Examples

Intensification - Using smaller quantities of hazardous substances

• Reducing inventory of phosgene through improved process control and insitu production

20

30

40

50

60

70

80

90

100

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

% IN

VEN

TORY

VS

1985

BA

SE Y

EAR

YEAR

PHOSGENE INVENTORY REDUCTION

• Using continuous reaction processes in stead of batch reaction processes for polyethylene and polypropylene plastic resins


Intensification - Using smaller quantities of hazardous substances

• Redesign of an Acrolein plant to dramatically reduce Acrolein inventory on site. Later a new process unit was built to convert Acrolein to a less hazardous derivative reducing the transportation risk (Substitution).

Examples


Substitution - Replacing a material with a less hazardous substance

• Replacement of benzene as azeotroping agent

• Using sodium hypochlorite bleach to replace chlorine gas as a water purification chemical

• Replacement of a flammable solvent in a process with a less hazardous solvent

Note: Substitution is limited by the chemistry of the process and often requires new equipment

Examples


Attenuation - Using less hazardous conditions or less hazardous form of material

• Use of a new generation of catalysts in an exothermic polymerization process that loose activity upon temperature increase (loss of cooling etc.)

• Storing highly toxic or flammable materials (e.g., chlorine, LNG) as a refrigerated liquid at atmospheric pressure rather than at atmospheric temperature under pressure

• Using aqueous HCl solution rather anhydrous HCl reduces spill consequences

Examples


Limitation of Effects - Designing to minimize impact of release of material or energy

• Use of small diameter piping or restricting orifices to limit flow rate

• Designing process equipment to contain the maximum foreseeable pressures

• Use of high wall dikes and other secondary containment to severely limit surface area available for evaporation of toxic liquid spills

Examples


Simplification & Error Tolerance - Designing to eliminate or tolerate operating errors.

• Design equipment to make incorrect assembly impossible in reactor cleaning

• Eliminate use of hoses in hazardous services in favor of hard piped connections

• Use of Safety Instrumented Systems to provide automated emergency shutdown of critical operations

Examples


Strategy for Safer Operations:A Multi-faceted Approach

• Design using inherently safer technology• Employ passive safeguards• Use active controls and mitigation• Adopt procedural methods (Operations and

Maintenance)• Use Operating Discipline Management System

All strategies work together to achieve safer operations


• It’s never too late to consider inherent safety.• The Inherent Safety Checklist is included in PHA• Applying new inherently safer technology to existing

plants often is not economically feasible.

Key Learning #1:Making Chemical plants safer through the application of inherently safer technology is an evolutionary process.


Key Learning #2:Inherently safer technology is best implemented early in a project when a chemical process is first designed.

• New chemical processes will eventually replace the processes of today; these new facilities offer the best opportunity to apply inherently safer technology

• An Inherent Safety Checklist as part of the Project Methodology

• Fundamental changes in chemistry and materials are often cost prohibitive after the plant is built.


Key Learning #3:Inherently safer technology can be misapplied and result in higher risk if the “big picture” is not properly considered. • Minimizing the size of a raw material storage tank will

reduce potential impact in the process area but if the tank is too small to unload an entire tank car of material at once you will increase the risk of the unloading operation

• Substituting bleach for chlorine in water treatment reduces risk at the site of the water treatment plant but increases the amount of chlorine required at the bleach manufacturing site. Is overall risk reduced?


• There are many facets of inherently safer technology.

• Government regulation tends to dictate a “one-size fits all” approach.

• Misapplication of inherently safer technology can result in increased risks.

Key Learning #4:It would be unsound to attempt to regulate the use of Inherently Safer Technology.


• Inherent safety must employed along with other risk reduction strategies

• It takes expert knowledge to properly evaluate the risk reduction potential of a proposed change.

Key Learning #5:Inherently safer technologies are not a panacea for safe operations.

Inherently Safer Technology

Documents

Transcript of Inherently Safer Technology