m09 Batch Hazop

HAZO HA ZOP P Study Study of Ba Batc tch h Plan Plants ts an and d Ope Opera ratio tions ns

Data Requirements 

Definition of steps, including process conditions, agitation / mixing, charging, reacting, discharging etc.



Interlocks in operation during step (e.g. ( e.g. valves held closed)



Necessary conditions to move to next step



Details of alarms, including “watchdog” timers

© Det Norske Veritas AS. All rights rights reserved.

2

Preparations Leader and some members should prepare before study to understand: 

Hazards of the process



Control scheme, including sequence control



Cycle of operations and main process steps



Study sections to be used

© Det Norske Veritas AS. All rights reserved.

3

Preparations Leader must decide how to carry out the study, after preparing the following: 



A matrix showing the process steps and the study sections, and showing which section is active in which step A chart showing which valves, drives, pumps and instruments are active in each step of the process


4

Guidewords 

The standard guidewords from Process HAZOP are used



Additionally, guidewords related to the following parameters are used: - Time - Step - Action


5

Additional Guidewords: Time 

NO TIME



Event or action missed altogether



MORE TIME



Event occurs after it should or takes longer time



LESS TIME



Event occurs before it should or takes shorter time



WRONG TIME



Event or action occurs when it should not


6

Additional Guidewords: Step 

STEP TOO LATE



An input fault prevents step on



STEP TOO EARLY



Step on conditions met early



STEP LEFT OUT



Operator forgets a step



STEP BACKWARDS



Fault causes incorrect transfer to another step


7

Additional Guidewords: Step 

STEP TOO LATE



An input fault prevents step on (= MORE TIME)



STEP TOO EARLY



Step on conditions met early (= LESS TIME)



STEP LEFT OUT



Operator forgets a step (= NO TIME)



STEP BACKWARDS





Thus, guidewords associated with the parameter STEP can be addressed by TIME


Fault causes incorrect transfer to another step (= WRONG TIME)

8

Additional Guidewords: Action 

PART ACTION



One sub-action in a step is missed



EXTRA ACTION



Operator includes an action from another step



WRONG ACTION



An aberration - needs serious brain storming


9

Procedure: Option 1 – Step by Step 



Consider 1st step, for all active sections, then all inactive sections Use all guidewords for active sections, not for inactive sections, where “becomes active” is the deviation



Take each step in turn and repeat this process



Identify and study other sections not in normal operation


10

Step by Step Method st

1 Step

st

Take 1 Active Section

Complete Logsheet

No Take next active section

Last Active Section ?

Yes Take other inactive sections

Complete Logsheet

Last Step ? Yes Finshed


11

Next

Step

Procedure: Option 2 – Section by Section 

Consider 1st section, for all steps: - First for steps when it is active - Then for others



Use all guidewords for active steps, not for inactive steps, where “becomes active” is the deviation



Take each section in turn, and repeat this process



Identify and study other sections not in normal operation


12

Section by Section Method st

1 Section

st

Take 1 Step in which this section is active

Complete Logsheet

No Take next step in which this section is active

Last Step in which this section is active ?

Yes Take steps in which this Section is not active

Complete Logsheet

Last Section ? Yes Finshed


13

Next

Section

Procedure: Which Option? Consider matrix showing steps and sections: 

If there are fewer steps, use step-by-step



If there are fewer sections, use section-by-section



If there are equal numbers of each, it does not matter which option you choose


14

Refrigerated Ship Loading: Batch HAZOP Example XCV4

V281

T1

P1

Q.R.C. 10” 150#

T1

V284

V282 1.5”

10” Export Line 1.5”

XCV3

V78 1”

V280

3”

V283 V80

V77

To Sea

e.g. Ammonia or LNG


8” Vapour Return Line

15

Analysis Matrix for Refrigerated Ship Loading Steps

(1) Cool Line

(2) Connect Arm

(3) Cool Arm

Delivery Line

A

I

A

A

I

I

Recirculation Line

A

I

I

I

I

I

Loading Arm

I

A

A

A

A

A

Sections

(4) (5) (6) Load Ship Purge and Disconnect Drain Arm Arm



Which approach is recommended: section-by-section or step-by-step?



In what order should the steps be considered for each section?


16

Open/Closed Valves etc. for Refrigerated Ship Loading Steps

(1) Cool Line

(2) Connect Arm

(3) Cool Arm

V77

O

O

C

C

C

M

V80

C

C

C

C

C

C

V78

C

C

O

O

C

C

V284

C

C

C

C

C

C

XCV3

C

C

O

O

C

C

V280

C

C

C

C

C

C

XCV4

C

C

C

C

C

C

V281

C

C

O

O

O

C

QRC

D

Conn

Conn

Conn

Conn

D

V282

C

C

O

O

O

C

V283

C

C

C

C

O

C

Valves etc.

(4) (5) (6) Load Ship Purge and Disconnect Drain Arm Arm

O = Open; C = Closed; D = Disconnected; Conn = Connected


17

Batch Reactor HAZOP Example Distillation Column

Nitrogen Purge Solvent A

Condenser

HV-1

Reactant B

PCV-1

HV-2

Reactant C

HV-5

Coolant in TCV-2 Catalyst D

HV-3 HV-7

Stirrer AG-1

HV-4

AV-1

Vent

Receiver R2

Heating/cooling fluid TCV-1

Vacuum

Distillate Transfer

Batch Reactor R1 P-3

HV-6 Product discharge to storage P-1

P-2

PCV-2


Excess heating/cooling fluid discharge

Slide 18

HAZOP Procedure For Batch Units VALVE/EQUIPMENT ITEM PROCESS STEP

HV-1

HV-2

HV-3

HV-4

HV-5

HV-6

HV-7

PCV1

PCV2

AV-1

TCV1

TCV2

AG-1

P-1

P-2

P-3

Before start of batch

C

C

C

C

C

C

C

C

C

C

C

C

Off

Off

Off

Off

1. Nitrogen Purge

C

C

C

C

C

C

O

C

C

O

C

C

Off

Off

Off

Off

2. Charging Solvent A

O

C

C

C

C

C

C

C

C

O

C

O

Off

Off

Off

Off

3. Charging Reactant B

C

O

C

C

C

C

C

C

C

O

C

O

On

Off

Off

Off

4. Charging Reactant C

C

C

O

C

C

C

C

C

C

C

C

O

On

Off

Off

Off

5. Charging Catalyst D

C

C

C

O

C

C

C

C

C

C

C

O

On

Off

Off

Off

6. Heating

C

C

C

C

C

C

C

C

M

C

M

O

On

On

Off

Off

7. Pull Vac on Reactor

C

C

C

C

O

C

C

M

M

C

M

O

On

On

Off

Off

8. Distillation

C

C

C

C

O

C

C

M

M

C

M

O

On

On

Off

Off

9. Break vacuum

C

C

C

C

O

C

O

C

M

C

M

O

On

On

Off

Off

10. Cooling

C

C

C

C

C

C

C

C

M

O

M

O

On

On

Off

Off

11. Discharge Distillate

C

C

C

C

C

C

C

C

M

O

M

O

On

On

Off

On

12. Discharge Product

C

C

C

C

C

O

C

C

C

O

C

C

Off

Off

On

Off

Symbols used:

C = closed O = open M = modulating


Slide 19

HAZOP Procedure For Batch Units PROCESS STEPS STUDY SECTIONS

1

2

3

4

5

6

7

8

9

10

11

12

1. Nitrogen purge

A

I

I

I

I

I

I

I

A

I

I

I

2. Reactor

A

A

A

A

A

A

A

A

A

A

A

A

3. Jacket heating/cooling

I

I

I

I

I

A

A

A

A

A

A

I

4. Heating/cooling supply

I

I

I

I

I

A

A

A

A

A

A

I

5. Heating/cooling discharge

I

I

I

I

I

A

A

A

A

A

A

I

4. Solvent A

I

A

I

I

I

I

I

I

I

I

I

I

5. Reactant B

I

I

A

I

I

I

I

I

I

I

I

I

6. Reactant C

I

I

I

A

I

I

I

I

I

I

I

I

7. Vacuum system

I

I

I

I

I

I

A

A

I

I

I

I

8. Vent system

A

A

A

I

I

I

I

I

I

A

A

A

9. Catalyst D

I

I

I

I

A

I

I

I

I

I

I

I

10. Distillation Column & Condenser

A

A

A

A

A

A

A

A

A

A

A

A

11. Condenser coolant

I

A

A

A

A

A

A

A

A

A

A

I

12. Receiver

A

A

A

A

A

A

A

A

A

A

A

A

13. Distillate transfer system

I

I

I

I

I

I

I

I

I

I

A

I

14. Product Discharge system

I

I

I

I

I

I

I

I

I

I

I

A

circulation system


© Det Norske Veritas AS. All ri hts

22 May

Slide 20

Batch HAZOP Logsheet Project:

Batch Reactor HAZOP Node: 001

Node Description:

Step 1 Nitrogen Purge to reactor Section Nitrogen purging line to reactor (active for this step)

GUIDEWORD/ DEVIATION

No Flow

More Pressure

Less Time

CAUSES

CONSEQUENCES

Page: 1

SAFEGUARDS

REC #

RECOMMENDATION

R1

Provide a flowmeter in the nitrogen supply line to indicate nitrogen flow to the reactor during purging.

Bursting disc system on R2 reactor set at 3 Barg. (not shown on drawing).

Ensure that the nitrogen supply pressure is below 1 Barg to prevent failure of the reactor bursting disc should the reactor become pressurised with nitrogen. Include in operating procedures for Step 1 the time the reactor must be purged with nitrogen for before proceeding to Step 2.

Manual valve closed No nitrogen supply to reactor. or line blockage. There no purging and potential No nitrogen supply. flammable atmosphere in the reactor when solvent is charged (Step 2). Potential fire or explosion if there is a source of ignition. Nitrogen supply Possible overpressure of reactor, pressure too high distillation system and receiver which could cause failure.

Operator knowledge and training. Reliable nitrogen supply.

Operator does not purge reactor for long enough.

As for ‘No Flow’ (above).


As for ‘No Flow’ (above).


22 May

R3

Slide 21


Batch Reactor HAZOP

Node Description: Step 1 Section GUIDEWORD/ DEVIATION

CAUSES

Reverse low Reacor manway (Reactor) open

Less Flow (Vent Line)

Node: 002

Nitrogen Purge to reactor Reactor, Distillation line, condenser, receiver and vent line (all active for this step) CONSEQUENCES

SAFEGUARDS

Discharge of nitrogen around reactor area. Possible hazard to operators if they are close to the reactor

Standard pre-checks for this process are that reactor manway should be bolted closed before starting the nitrogen purge. Standard pre-checks for this process are that catalyst charge valve should be closed before starting the nitrogen purge. As before. Operating procedures.

Catalyst charge valve open.

As above.

Vent valve closed during nitrogen purging.

Inadequate purging with same consequences as for ‘No Flow’ and More Pressure in Node 1 (i.e. inadequate purging and increase in pressure in reactor system).


Page: 1


22 May

REC #

RECOMMENDATION

Slide 22


Node: 003


More flow (vacuum line)

Page: 1

Nitrogen Purge to reactor Other non-active sections in this step.

CAUSES

Vacuum valve PCV1 open when purging reactor with nitrogen.


CONSEQUENCES

SAFEGUARDS

Vacuum created in reactor and increased purging flow. No hazard.


22 May

REC #

RECOMMENDATION

Pressure gauge on reactor.

Slide 23


Node: 001


CAUSES

No flow

Operator forgets to charge solvent. Valve blocked.

More time.

Operator error. Batch meter set incorrectly.

Wrong Action

Operator error. Wrong solvent supply routed to reactor.


Page: 2

Charging Solvent A to reactor Solvent A feed line to reactor CONSEQUENCES

SAFEGUARDS

No solvent transfer to reactor. Potential exothermic reaction when other eactants are heated during the process. This would cause loss of product (failed batch). Too much solvent added to reactor. Reactor may be overfilled when reactants are added. Possible discharge of reactants and solvent from the catalyst charging connection during Step 5. Wrong solvent transferred to reactor. Loss of product (failed batch). Potential hazard of using incorrect solvents not known.

Operator checks solvent quantity added on meter upsteam. This is entered on the batch record sheet.


22 May

Operating procedures.

Operating procedures.

REC #

RECOMMENDATION

R4

Provide software interlock on batch meter for Solvent A to ensure that batch quantity cannot be exceeded.

Check what other solvent could be mistakenly added to the reactor and check whether these could create a hazard if they were used instead of Solvent A.

Slide 24


Node: 005

Node Description: Step 2 Section GUIDEWORD/ DEVIATION Less flow

CAUSES

Reactor drain valve open


Page: 1

Charging Solvent A to reactor Reactor (active during this step) CONSEQUENCES

SAFEGUARDS

Solvent discharged from reactor drain line. Inadequate solvent in reactor. Possible effect on reaction/product quality.

Operating procedues and pre-start checks that run out valve is closed before adding solvent. Solvent loss would be small since P2 must be used to remove material from the reactor


22 May

REC #

RECOMMENDATION

Slide 25


Node: 005

Node Description: Step 2 GUIDEWORD/ DEVIATION

Section CAUSES

Page: 1

Charging Solvent A to reactor Other non active sections CONSEQUENCES

SAFEGUARDS

REC #

RECOMMENDATION

No hazards identified.



22 May

Slide 26

Safeguarding life, property and the environment www.dnv.com


27

m09 Batch Hazop

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