1、Loss Prevention,Loss prevention in chemical industries involve: Identification and assessment of major hazards Control of hazards by containment, substitution, improved maintenance Control of process by utilizing automatic control, relief system , interlock, alarm Limitation of loss when accident ha

2、ppens,Loss Prevention,The major formalized techniques are: Hazards and Operability (HAZOP) Fault Tree Analysis (FTA) Failure mode-and-effect analysis (FMEA) Safety indexes Safety audit,What is HAZOP?,Systematic technique to IDENTIFY potential HAZard and OPerating problems A qualitative technique bas

3、ed 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 Considerable engineering insight is involved,4,HAZOP study are applied during : Normal operation Foresee

4、able 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,HAZOP Team,Team Leader Team S

5、ecretary Process Engineer Mechanical Engineer Commissioning/Operations Engineer/Manager Instrument Engineer,HAZOP studies are carried out using a brainstorming approach by a team, chaired and coordinated by a qualified person experienced in HAZOPs:,6,HAZOP is a systematic, reasonably comprehensive a

6、nd flexible. It gives good identification of cause and excellent identification of critical deviations. The use of keywords is effective and the whole group is able to participate. HAZOP is an excellent well-proven method for studying large plant in a specific manner.,Strength of HAZOP,7,HAZOP is ve

7、ry time consuming and can be laborious with a tendency for boredom for analysts. It tends to be hardware-oriented and process-oriented, although the technique should be amenable to human error application. HAZOP does not identify all causes of deviations and therefore omits many scenarios.,Weakness

8、of HAZOP,8,NONE /Noe.g., NO FLOW caused by blockage; pump failure; valve closed or jammed : REVERSE Opposite, e.g., REVERSE FLOW caused by pump failure MORE Quantitative increase, e.g., MORE FLOW, Temp, LESS Quantitative increase, e.g., LESS FLOW, Temp, As Well AsQualitative increase, e.g. impurity.

9、 PART OF Qualitative decrease, Change in composition high or low concentration of mixture; additional reactions in reactor or other location ; feed change. Other thanNothing of the intent happen, completely different occurs,Guide Words,HAZOP Steps,These guide words are applied to flow, temperature,

10、pressure, liquid level and composition. Deviation of these variables from normal operation is considered The consequences of these deviations on the process is then assessed. The measures needed to correct these consequences are then established,This process enables a comprehensive evaluation of Haz

11、ard control systems and produces recommendations for any necessary modifications. The overall result is a reduction in both hazards and potential operational problems,11,HAZOP STUDY REPORT FORM TITLE : Sheet 1 of LINE 1 :,HAZOP Study Form,Storage Tank,HAZOP Table - level,HAZOP Table - pressure,Hazop

12、 Table - composition,HAZOP Table - Temperature,17,Preliminary HAZOP Example,Refer to reactor system shown. The reaction is exothermic. A cooling system is provided to remove the excess energy of reaction. In the event of cooling function is lost, the temperature of reactor would increase. This would

13、 lead to an increase in reaction rate leading to additional energy release. The result could be a runaway reaction with pressures exceeding the bursting pressure of the reactor. The temperature within the reactor is measured and is used to control the cooling water flow rate by a valve. Perform HAZO

14、P Study,18,Preliminary HAZOP on Reactor,19,Case Study Shell & Tube Heat Exchanger,Using relevant guide works, perform HAZOP study on shell & tube heat exchanger,20,HAZOP on Heat Exchanger,Documents needed for HAZOP Study, For Preliminary HAZOP Process Flow Sheet ( PFS or PFD ) Description of the Pro

15、cess For Detailed HAZOP Piping and Instrumentation Diagram ( P & ID ) Process Calculations Process Data Sheets Instrument Data Sheets Interlock Schedules Layout Requirements Hazardous Area Classification Description of the Process,Planning for HAZOP,Additional required information: Safety procedures

16、 documents Relief/venting philosophy Chemical involved Piping specifications Previous HAZOP report,Planning for HAZOP,Carry out the study Record the results (may need a secretary) Follow-up of actions noted final report contain resolution of all recommended actions must appoint someone as leader to

17、check progress of action team may meet again if answers to questions do not simply lead to an action team may meet again if significant design changes in interim report,Responsibility of HAZOP Team Members,HAZOP leader Plan sessions and timetable Control discussion Limit discussion Encourage team to

18、 draw conclusion Ensure secretary has time for taking note Keep team in focus Encourage imagination of team members Motivate members Discourage recriminations Judge importance issues,HAZOP Secretary Take adequate notes Record documentations Inform leader if more time required in taking notes If uncl

19、ear, check wording before writing Produce interim lists of recommendations Produce draft report of study Check progress of chase action Produce final report,Responsibility of HAZOP TeamMembers,Process Engineer Provide a simple description Provide design intention for each process unit Provide inform

20、ation on process conditions and design conditions Provide a simple description Provide design intention for each process unit Provide information on process conditions and design conditions,Responsibility of HAZOP TeamMembers,Mechanical Design Engineer Provide specification details Provide vendor pa

21、ckage details Provide equipment and piping layout information Instrument Engineer Provide details of control philosophy Provide interlock and alarm details Provide info on shutdown, safety features,Responsibility of HAZOP TeamMembers,Plant Engineer or Manager Provide information on compatibility with any existing adjacent plant Provide details of site utilities and services Provide (for stu