Production of Synthesis Gas By Partial Oxidation of Natural

GasEnvironment, Safety, and

Economic Evaluation

Group II : Bibi AL-Mutawa’aMariam AL-Shamma’aDalal AL-Othman

Prof. Mohamed A. Fahim

Eng. Yusuf Ismail Ali

Prof. Mohamed A. Fahim

Eng. Yusuf Ismail Ali

Bibi Yousef Al-Motawa204112571

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Plant SafetyPlant SafetyBy: Bibi Al-Mutawa’a

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• Systematic technique to identify potential hazard and Operating problems

• A formal systematic rigorous examination to the process and engineering facets of a production facility

• A qualitative technique based on “guide-words” to help provoke thoughts about the way deviations from the intended operating conditions can lead to hazardous situations or operability problems

• hazop is basically for safety

- Hazards are the main concern

- Operability problems degrade plant performance (product quality, production rate, profit)

• Considerable engineering insight is required - engineers working independently could develop different results

What is HAZOP?

Objective of HAZOP

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• For identifying cause and the consequences of operations of equipment and associated operator interfaces in the context of the complete system.

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• HAZOP identifies potential hazards , failures and operability problems.

• Its use is recommended as a principal method by professional institutions and legislators on the basis of proven capabilities for years.

• It is most effective as a team effort consists of plant and prices designers, operating personnel, control and instrumentation engineer.

• It encourages creativity in design concept evaluation.

• Necessary changes to a system for eliminating or reducing the probability of operating deviations are suggested by the analytical procedure.

• HAZOP provides a necessary management tool and bonus in so far that it demonstrates to insurers and inspectors evidence of comprehensive thoroughness.

How and Why HAZOP is Used

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• HAZOP reports are an integral part of plant and safety records and are also applicable to design changes and plant modifications, thereby containing accountability for equipment and its associated human interface throughout the operating lifetime.

• HAZOP technique is now used by most major companies handling and processing hazardous material, especially those where engineering practice involves elevated operating parameters :

- oil and gas production

- flammable and toxic chemicals

- pharmaceuticals etc

• Progressive legislation in encouraging smaller and specialty manufacturing sites to adopt the method also as standard practice.

How and Why HAZOP is Used

Features of HAZOP Study

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Subsystems of interestline and valve ,Equipment, Vessels

Modes of operationNormal operationStart -up mode

Shutdown modeMaintenance /construction /

inspection mode

Trigger events Human failureEquipment /instrument/component

failureSupply failure

Emergency environment eventOther causes of abnormal operation,

including instrument disturbance

Features of HAZOP Study

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Effects within plant Changes in chemical conditionsChanges in inventory

Change in chemical physical conditions

Hazardous conditionsRelease of materialChanges in material hazard characteristics

Operating limit reachedEnergy source exposed etc.

Corrective actionsChange of process designChange of operating limits

Change of system reliabilityImprovement of material containment

Change control systemAdd/remove materials

Features of HAZOP Study

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How would hazardous During normal operation

conditions detected ?Upon human failure

Upon component failure In other circumstances

Contingency actions Improve isolation

Improve protection

Documents Needed for HAZOP Study

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Process Flow Sheet ( PFS or PFD )Description of the ProcessProcess Data SheetsInstrument Data SheetsHazardous Area Classification Description of the Process

Before Detailed HAZOP

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The development will follow a normal standard procedure and include the following considerations:

Basic process control system - this is a closed loop control to maintain process within an acceptable operating region.

Alarm system - this is to bring unusual situation to attention of a person monitoring the process in the plant

Safety interlock system - this is to stop operation or part of the process during emergencies.

Relief system - this is to divert material safely during emergencies.

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GUIDE WORDS

POSSIBLE CAUSES DEVIATION ( FROM DESIGN AND/OR OPERATING INTENT )

CONSEQUENCES

ACTION(S) REQUIRED OR RECOMMENDEED

HAZOP Study Procedure

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NONE No forward flow when there should be

MORE More of any parameter than there should be, more flow, more pressure, more temperature.

LESS As above, but "less of" in each instance

PART System composition difference from what it should be.

MORE THAN More "components" present than there should be for example, extra phase, impurities.

OTHER What needs to happen other than normal operation, e.g. start up, shutdown, maintenance

Guide Words

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NONE e.g., NO FLOW caused by blockage; pump failure; valve closed or jammed : leak: valve open ;suction vessel empty; delivery side over - pressurized : vapor lock ; control failure

REVERSE e.g., REVERSE FLOW caused by pump failure : NRV failure or wrongly inserted ; wrong routing; delivery over pressured; back- siphoning ; pump reversed

MORE OF e.g., MORE FLOW caused by reduced delivery head ; surging ; suction pressurised ; controller failure ; valve stuck open leak ; incorrect instrument reading.

Guide Words

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MORE OF MORE TEMPERATURE, pressure caused by external fires; blockage ; shot spots; loss of control ; foaming; gas release; reaction;explosion; valve closed; loss of level in heater; sun.

LESS OF e.g., LESS FLOW caused by pump failure; leak; scale in delivery; partial blockage ; sediments ; poor suction head; process turndown.

LESS e.g., low temperature, pressure caused by Heat loss; vaporization ; ambient conditions; rain ; imbalance of input and output ; sealing ; blocked vent .

PART OF Change in composition high or low concentration of mixture; additional reactions in reactor or other location ; feed change. 

Guide Words

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MORE THAN Impurities or extra phase Ingress of contaminants such as air, water, lube oils; corrosion products; presence of other process materials due to internal leakage ; failure of isolation ; start-up features.

OTHER Activities other than normal operation start-up and shutdown of plant ; testing and inspection ; sampling ; maintenance; activating catalyst; removing blockage or scale ; corrosion; process emergency ; safety procedures activated ; failure of power, fuel, steam , air, water or inert gas; emissions and lack of compatibility with other emission and effluents.

Guide Words

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HAZOP study are applied during :

• Normal operation

• Foreseeable changes in operation, e.g. upgrading, reduced output, plant start-up and shut-down

• Suitability of plant materials, equipment and instrumentation

• Provision for failure of plant services, e. g . steam, electricity, cooling water

• Provision for maintenance.

HAZOP Study

Case Study – Shell & Tube Heat Exchanger

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Using relevant guide works, perform HAZOP study on shell & tube heat exchanger

Processfluid

Cooling water

HAZOP on Heat Exchanger

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Guide Word Deviation Causes Consequences Action

Less Less flow of cooling water

Pipe blockage

Pipe leakage

Heat tubes burst

Temperature of process fluid remains constant

Process fluid temperature too low

Explosion

High Temperature Alarm

Installation of flow meter

Flow alarm or shutdown

Less pressure in tubes

Burst pipe Explosion Alarm low pressure

More More cooling flow

Failure of cooling water valve

Temperature of process fluid decrease (TOO LOW)

Low Temperature Alarm

Flow alarm

More pressure on tube side

Failure of process fluid valve

Tube blockage

Bursting of tube

Tube failure

Install high pressure alarm

Pressure relief system on tubes

HAZOP on Heat Exchanger

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Guide Word Deviation Causes Consequences Action

NONE No cooling water flow

Failure of inlet cooling water valve to open

Process fluid temperature does not decreased

Install Temperature indicator before and after the process fluid line

CONTAMINATION Process fluid contamination

Contamination in cooling water

Outlet temperature too low

Proper maintenance and operator alert

Other Maintenance Equipment failure , pipe leak

Process stops Ensure all pipes and fittings are constructed of the right material and are stress relieved

HAZOP on Heat Exchanger

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Part of Low fuel gas Empty storage Cooler freezing Install low flow alarm in fuel gas

Low cooling water

Empty storage Decrease absorption

Increase pollution

Increase impurities in syngas product

Install low level alarm on cooling water

More than Organic acid present

Corrosion of tube

Less cooling and crack of tube

Hardness of cooling water

Proper maintenance to check suitability of material of construction

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HAZOP TEAM

Team Leader / Chairman Extensive experience of process design and preferably commissioning and operations in a processing environment. Good motivation and meeting leadership skills are required. Independent of the design team.

Secretary / Scribe Familiar with the technology and terminology of the study. Competent to record the proceedings with a minimum of direction from the chairman. Keyboard skills necessary for word processor and software recording packages.

Independent Process Engineer Senior chemical/process engineer with at least five years experience in the relevant process technology. Independent of the design team. Role is to question process design assumptions, ensure design is to appropriate standards, advise team about process technology and assess likely consequences of process deviations.

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Operations Representative Considerable operating experience in the type of process under study. Role is to describe operating practices, identify potential for deviation from operating intent and provide information about plant stability, ergonomics, means of preparing plant for maintenance, etc.

Design Process Engineer Familiar with the design intent. Role is to describe overall scheme and process safety systems, provide design intention and process conditions for each plant section, and explain process consequences of deviations.

Instrument / Control Engineer Provide information about overall control and safeguarding philosophy, interlocks and alarms, plant shutdown system, safety features, e.g. F&G detection.

Plant Engineer Provide information about compatibility with existing plant, site utilities, plant layout, maintainability and reliability requirements

Safety Engineer Provide information about plant safety philosophy, safety equipment, emergency response procedures, previous incidents and matters concerning public safety.

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CONCLUSION

During the design of a new plant, design personnel are under pressure to keep the project on schedule.  This pressure frequently results in errors and oversights.  HAZOP study is an opportunity to correct these before such changes become too expensive, or impossible to accomplish.

Besides safety hazards, the HAZOP technique is very effective for identifying plant operability problems, threats to the environment, product quality, plant throughput and for highlighting critical maintenance requirements.

Benefit of hazop

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CONCLUSION

Limitation of Hazop HAZOP is a powerful technique but the extent to which it can uncover all foreseeable hazards is limited by the knowledge, experience and deductive skills of the HAZOP team. For these reasons, it is difficult to assess the ‘quality' of a given HAZOP in any objective or auditable way. Audits can be carried out to establish that the process has been followed, but they cannot verify the competence of the team.

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Thank you