INSTRUMENTATION AND CONTROLS FOR SAFETY .


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Naturally SAFE DESIGN. Procedure RISK MANAGEMENT METHODS USED DURING THE DESIGN PHASE CAN BE PUT INTO 4 CATEGORIES:InherentPassiveActiveProceduralTARGET IS A FAIL-SAFE INSTALLATIONFROM: Dennis C. Hendershot and Kathy Pearson-Dafft, Safety Through Design in the Chemical Process Industry: Inherently Safer Process Design , AIChE Process Plant Safety Symposium, 27OCT98.
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INSTRUMENTATION AND CONTROLS FOR SAFETY M. B. Jennings CHE 185

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INHERENTLY SAFE DESIGN PROCESS RISK MANAGEMENT METHODS USED DURING THE DESIGN PHASE CAN BE PUT INTO 4 CATEGORIES: Inherent Passive Active Procedural TARGET IS A FAIL-SAFE INSTALLATION FROM: Dennis C. Hendershot and Kathy Pearson-Dafft, Safety Through Design in the Chemical Process Industry: Inherently Safer Process Design , AIChE Process Plant Safety Symposium, 27OCT98

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INHERENT SAFETY DESIGN Inherent — Eliminating the peril by utilizing materials and process conditions which are non-dangerous. Minimize — Reduce amounts of risky substances Substitute — Use less dangerous substances Moderate — Use less perilous process conditions, less unsafe types of materials, or arrange offices to minimize affect from risky material discharges or uncontrolled vitality discharge Simplify — Configure offices to improve operation

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PASSIVE SAFE DESIGN Passive — Minimizing the danger by process and hardware configuration highlights which lessen either the recurrence or result of the danger without the dynamic working of any gadget. Area of offices – division of start sources and fills from different offices Design gear for configuration weight in overabundance of the adiabatic weight from a response.

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ACTIVE SAFE DESIGN Active — Using offices to distinguish and revise handle conditions: controls security interlocks checking frameworks for perils that create over a long haul and crisis shutdown frameworks to identify and amend prepare deviations.

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PROCEDURAL SAFE DESIGN Procedural — Prevention or minimization of episode effects utilizing: Safe working strategies and administrator preparing Administrative security checks Management of Change Planned crisis reaction

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DESIGN IN OVERALL SAFETY MANAGEMENT Art M. Dowell, III, Layer of Protection Analysis, 1998 PROCESS PLANT SAFETY SYMPOSIUM, October 27, 1998 Houston, TX

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DESIGN OF SAFETY INSTRUMENTED SYSTEMS ACTIVE INHERENTLY SAFE DESIGN PROCEDURE (Separate instrumentation and control segment in CHE 165 Design) First Level – Alarm frameworks for out of range circumstances and administrator activity Second Level – Interlock frameworks to naturally enact security gadgets Third Level – Devices to minimize effect of crazy conditions

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USE OF HAZAN AND HAZOP PHA\'s (Process Hazards Analysis) Are utilized to characterize regions of concern HAZAN and HAZOP give an outline of the sort of hazard connected with different process areas and operations Frequency ought to be resolved Intensity ought to be resolved

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OVERPRESSURIZATION EXAMPLE OVERPRESSURIZATION IS THE SUBJECT OF NUMEROUS CODES & REGULATIONS AIChE Design Institute for Emergency Relief Systems (DIERS) OSHA 29 CFR 1910.119 – Process Safety Management of Highly Hazardous Chemicals NFPA 30 – Flammable & Combustible Liquids API RP 520 and API RP 521 – Pressure Relieving Devices and Depressurization Systems ASME Boiler & Pressure Vessel Code ASME Performance Test Code 25, Safety & Relief Valves

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SOURCES OF OVERPRESSURIZATION API 521 LISTS THE FOLLOWING CATEGORIES OF SOURCES

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FIRST LEVEL DESIGN HOW ARE SOURCES ADDRESSED FOR A STORAGE TANK? Thing 1 in past rundown - Closed outlets on vessels Would be a sympathy toward a spout utilized for weight control in the tank, amid filling operations. Maybe a transitory visually impaired spine would have been left set up after a support operation. A weight help valve may breakdown. A PAH weight switch ( Δ P) could be introduced if there was quantifiable distinction between the Normal Operating Pressure and the Maximum Allowable Working Pressure.

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SECOND LEVEL DESIGN HOW ARE SOURCES ADDRESSED FOR A STORAGE TANK? Thing 1 in past rundown - Closed outlets on vessels Add a weight alleviation valve to permit gas to leave the tank and be coordinated to a proper flare or scrubber. Set direct needs toward be at or marginally over the Maximum Allowable Working Pressure Need an interlock to: Alarm to show valve has been enacted and getting unit (flare or scrubber) is actuated. Closed down a valve in the tank fill line and additionally close off a pump utilized for filling.

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THIRD LEVEL DESIGN HOW ARE SOURCES ADDRESSED FOR A STORAGE TANK? Thing 1 in past rundown - Closed outlets on vessels Add a break plate to calm to either a flare or scrubber. This level is to shield the gear from disappointment on a noteworthy scale Need to have a sign that the break circle has opened – commonly a wire over the plate Need to decide activities vital when the circle opens – quit filling, begin flare, and so on

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OTHER DESIGN CONSIDERATIONS An extensive stockpiling tank is filled physically by an administrator opening and shutting a valve. Once every year, the tank packs as the administrator is occupied by different exercises. A high weight caution is added to the tank. After the alert is included, the tank is normally stuffed twice per year. Why?

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EXAMPLE 1 After the alert was introduced, the administrator depended on it to show an abnormal state and did not oversee the filling nearly. The caution circle ended up having a disappointment rate of twice every year, so the framework was not as solid as the manual operation.

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OTHER CONSIDERATIONS – EXAMPLE 2 Fail-safe valves are either Air-to-Open or Air-to-Close, which liken to Fail Closed and Fail Open, individually. Prescribe the right valve for the accompanying procedures: Flammable dissolvable warmed by steam in a warmth exchanger. Valve is on the steam supply line. Exothermic response. Valve is on the reactant encourage line. Endothermic response. Valve is on the reactant encourage line. Gas-let go utility heater. Valve is on the gas supply line.

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EXAMPLE 2 - CONTINUED SPECIFY EITHER FAIL-CLOSED OR FAIL-OPEN FOR THE VALVES IN THESE SYSTEMS Remote-worked valve on the deplete for a capacity tank. Remote-worked valve on the fill line to a capacity tank. Gas-let go Combustion heater. Valve is reporting in real time supply line. Steam supply line. Valve controls the downstream steam weight from the heater.

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EXAMPLE 2 – SOLUTIONS 1 Valve to FAIL-CLOSED to anticipate overheating the dissolvable Valve to FAIL-CLOSED to maintain a strategic distance from a runaway response Valve to FAIL-CLOSED to keep away from reactor warm burdens. Valve to FAIL-CLOSED to stop gas stream to uncontrolled burning.

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EXAMPLE 2 – SOLUTIONS 2 Valve to FAIL-CLOSED to keep emptying material out of tank Valve to FAIL-CLOSED to forestall stuffing tank Valve to FAIL-OPEN to boost wind stream to heater Valve to FAIL-OPEN to maintain a strategic distance from confined overpressure of line

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EXAMPLE 3 4 kg of water is caught in the middle of gulf and release piece valves in a pump. The pump keeps on working at 1 hp. What is the rate of temperature increment in C/hr if the cP for the water is steady at 1 kcal/(kg C)? What will happen if the pump keeps on working?

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EXAMPLE 3 SOLUTION - 1 Assume adiabatic conditions for the estimations:

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EXAMPLE 3 SOLUTION - 2 Allowing the pump to keep on running will inevitably bring about high weight steam development. This could bring about the pump detonating. Including a warm switch or a high weight change to close down the pump can keep this from happening.

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