HAZOP Report.pdf - Environment Agency

Hudson Consultants Ltd

511A London Road

Davenham

Northwich

Cheshire

CW9 8NA

Tel: 07879 608616

E-mail: [email protected]

Date: 18th June 2019 Company no. 5573113

VAT. No. 868395267

To: HAZOP team – Brenntag

HAZOP Report – Brenntag Lutterworth – Clorious 2 production project rev 2 – May

2019

This note summarises the discussions and HAZOP for the Brenntag Lutterworth –

Clorious project carried out during a Lutterworth site visit in June 15. It has been

amended to rev 1 following a visit to Brenntag Duisburg (Germany) on the 21st July

2015. The visit report has been included as appendix 6.

Following an extended delay, the project has restarted in 2019. The intention is to

produce Clorious in the site new multi product filling plant. Several meetings have been

carried out in April & May 2019 to discuss this. This HAZOP report rev 2 has been

updated (in blue) based on the available information and knowledge. It is recommended

that the team reconvene in say June/July 19 to review and update as further information

becomes available.

HAZOP Chairman’s report

A multi-disciplinary team carried out the HAZOP over 1 day. The team represented an

adequate range of skills and knowledge required for a HAZOP study.

The documentation available is listed below. Each document was reviewed along with all

previous correspondence.

A visit was carried out to Brenntag Duisburg on the 21/7/15 to allow this HAZOP study

to be completed – see action 1.

The documentation that records the HAZOP is included. All guidewords on the attached

HAZOP checklist were considered for each stage. All parameters & associated deviations

were recorded. This allows the HAZOP record to be a full reporting method.

Actions have been listed below from both the documentation review and the HAZOP. It

is important that all actions are formally responded to (i.e. actioned). Therefore, the

HAZOP study is not considered complete until all actions have been signed off. The

HAZOP record sheet must be completed to demonstrate this.

Documents Considered

1. Brenntag Clorious – Description of production process v4.0 dated 2/5/17

2. P&IDs

a. 21292-07-0001AB01 - 25M3 Multi Product Blending P&ID

b. 21292-07-0003AB01 - Fume & Dust Scrubber P&ID

c. 21292-07-0011AB01 - Multi Product Filling P&ID

3. Brenntag European HSE Manual – Standard Procedure: Handling of Clorious2 ref

HSE_SP2.05_10 rev 0 dated 22/8/14

4. Clorious Material Specifications - Sodium Persulphate, Sodium Chlorite Solutions and

utilities

5. Brenntag MSDS - Sodium Chlorite Solution 10-25% v5.1 dated 6/9/13

6. Brenntag MSDS - Sodium Persulphate v4 dated 6/7/12

Actions (updated following the visit to Brenntag Duisburg on the 21/7/15 – see

appendix 6 for more details)

No. Action Update May 19

1 Visit the Clorious 2 plant at Brenntag Duisburg to gain a greater

understanding of the process, potential hazards and measures in place

to prevent, control & mitigate the hazards. This will then allow this

HAZOP to be completed. Include the following considerations:

• Does overheating of the Sodium Persulphate matter? Is there an

influence on the potential generation of ClO2 within the package?

This will determine the controls/interlocks required for heating.

Overheating is not considered to be a significant factor on the

potential generation of ClO2. It is considered good practice

though to heat the water on addition to the vessel and have a high

temperature trip – see action 9

• The Sodium Chlorite is added first to the drum/pack and then the

Sodium Persulphate. Does it matter if they are added

simultaneously or in reverse order? Is there an influence on the

potential generation of ClO2 within the package? This will

determine the controls/interlocks required for addition (i.e.

interlock between the 2 addition pumps or fill sequence etc).

The order of addition or if they are added together is not

considered to be a significant factor on the potential generation of

ClO2.

• How likely is ClO2 release when a drum is opened? Are exposure

limits likely to be breached without protection?

After the drum is filled, there is negligible generation of ClO2. In

any case, there is extraction. Release of ClO2 is more probable

during sampling – see actions.

• What are the other potential factors that could influence the

release of ClO2? For example:

o Sodium Chlorite concentration

o Sodium Chlorite quantity added

o Sodium Persulphate concentration

o Sodium Persulphate quantity added

Confirm high

temp trip on

multi product

blending tank

The main factor influencing the potential generation of ClO2 is the

concentration of Sodium Chlorite – see actions

2 Consider the Sodium Persulphate powder form and the potential for

dust when transferring into the mixing vessel. If an issue consider

purchasing a form that generates less dust or, if not possible, assess

what personnel protection is required i.e. LEV, RPE etc.

Not considered to be an issue due to the nature of the material used.

Complete

3 Prepare a Functional Design Specification (FDS) for the project

which is to include:

• Design of batch flowmeters to achieve accuracy requirements

(not required as propose to gravity fill)

• Design/location of batch filling systems (including data entry

limitations to minimise human failure)

• Provision of a local temperature gauge on the Sodium Persulphate

vessel to allow the operator to monitor the temperature prior to

adding Sodium Persulphate powder.

• Provision of emergency stops (location and function – LEV to be

kept operational)

• Interlock the agitator operation to a minimum vessel level i.e.

avoid agitator/vessel damage if run dry.

To be reviewed

Confirm high

level trip on

multi product

blending tank

will stop IBC

filling

4 Consider filling the Clorious package (i.e. drum/pack) on weigh

scales to allow overflow protection to be included.

Yes this is confirmed to be required.

Not required as

Permex system

considered

adequate

5 Consider filling the Clorious drum/pack via the dispensing system

(see supporting ref 9). This would have the potential advantage of

eliminating the step of removing the filling system and installing the

dispensing system after the drum/pack has been filled. This is of

significance as there is a potential for operator exposure to Chlorine

Dioxide fumes. It is believed that the DrumQuik Pro system has a

check valve such that when the filling coupler is removed after

filling, fume is prevented from being released whilst the plug is

inserted (to be confirmed).

Not possible – see appendix 6.

Not possible

6 Ensure that the scrubber operation is interlocked with the fill systems

(both Sodium Chlorite & Sodium Persulphate transfer pumps). The

scrubber package needs to be specified however typically the

interlock can be linked to the scrubber fan and the scrubber liquid

recirc (pump/flow).

To be done

7 Consider designing the effluent system to be self-contained (rather

than linking the system to the adjacent alkaline effluent system).

Spillages should be rare and rainwater ingress is minimised by the

use of a canopy. Any contaminated effluent can be collected and

transferred for waste disposal.

To be checked

8 Modify the site emergency plan to incorporate the required response

to potential incidents on this plant. Include the potential for spillage

and the provision of Sodium Bisulphite to ‘neutralise’ ClO2 and the

actions in the event of a ClO2 gas release.

To be done

9 Modify the P&ID to include the following changes (as well as some

of the actions above):

• Remove the lute arrangement on both vessels as they only require

an atmospheric vent.

• Sodium Persulphate vessel – add an air connection to the bottom

outlet in the event of powder build up and potential blockage.

• Heat the Demin water feed to the Sodium Persulphate vessel.

There should be an independent high temperature cut out on the

water (set at approx 45°C). Remove the heating element from the

vessel

• Sodium Chlorite vessel as HDPE

• Gravity feed both Sodium Persulphate & Sodium Chlorite into

the drum/keg on a weigh scale using batch feed systems with auto

close.

• Include both pH monitoring of the scrubber and the monitoring of

the scrubber recirculation flow. If both are out of range (pH < 8.5

and flow < set point to be determined) then the fill systems will

not be operational.

See action 6 re

scrubber

monitoring and

interlock

10 Modify the site layout to include the following changes:

• Sump to be moved away from the area where the operator is

filling the drum/pack.

• Scrubber to be located on opposite side (east rather than west

side) as this is the closest side to the point sources

No longer

relevant

11 Select the Clorious drum/pack storage location. The potential

requirement for refrigerated storage (to extend ‘shelf life’) to be

considered.

To be done

12 Consider the methodology of sampling. There is a potential for ClO2

exposure during this operation. Consider if there is a more inherently

safe option.

To be done

13 Develop a design for drum laundry plant taking into account the

Duisburg experience. Things to consider:

• Sodium Bisulphite IBC to have vapour extraction to scrubber on

vent (just in case the Sodium Bisulphite is consumed)

• Vapour extraction to be provided around where the drum is

handled (as ClO2 may be emitted from the nozzles when opened.

Carry out a HAZOP of this proposed design.

No longer

relevant as no

drum laundry.

Only new drums

to be used.

14 Consider the Sodium Chlorite dilution system design to minimise the

potential for ensuring that a diluted solution of 2.77% is achieved.

This may include the use of a batch dilution system that requires

water to be added prior to allowing the drum fill system to become

active. It will also require sampling and lab analysis to pass off the

batch prior to being used for drum fill.

Consider

controls to

check that

imported IBCs

are correct conc

15 Extraction system – ensure that the capacity is sufficient to withdraw

ClO2 vapours from the drum nozzle which would be generated if a

25% Sodium Chlorite solution was used to fill drums.

To be done

Appendix 1 - HAZOP RECORD SHEET

1. Complete this section before starting the study

Business: Brenntag Location: Lutterworth

HAZOP Ref: rev 2 HAZOP Title: Clorious project

Description (areas included) See below

Senior manager responsible: Rob Bagshaw HAZOP champion Rob Bagshaw

2. Complete this section at the start of the study

Study leader: Andrew Hudson Scribe: Andrew Hudson

Method used for scribing: Typed File name: Brenntag Lutterworth

Clorious project HAZOP report May 19 rev 2

Team members : Job title/function:

Andrew Hudson – Hudson Consultants Ltd – Hazop Chair & scribe

Alistair Hunter – Brenntag Leeds

Rob Bagshaw – Brenntag Lutterworth Ops Mgr.

Andrew Leach – Brenntag Lutterworth

Gareth Dobinson – Brenntag Leeds

Aneeb Chaudhry – Brenntag Leeds

Study dates: 2/6/15 & 21/7/15 & May 19

3. Complete this section when study is finished

Study checked for completion and logic ( )

HAZOP champion (responsible for follow up) Rob Bagshaw

Study approved for issue (signed study leader): ……………….. Date:

Study sheets issued ( ) Action sheets issued ( ) Date:

4. Sign off when ALL actions complete

All actions complete ( )

Signed (HAZOP champion): ……………………….. Date:

Audit complete (if requested): Date:

Signed (Senior manager): …………………………..

Please send a copy of this sheet with Parts 1 and 2 complete to A Hudson

HAZOP Study No. : Brenntag Lutterworth Clorious project HAZOP report May 19 rev

2

Date: 2/6/15 & 21/7/15 & May 19

Meeting No. : As dates

Team:

Andrew Hudson – Hudson Consultants Ltd – Hazop Chair & scribe

Alistair Hunter – Brenntag Leeds

Rob Bagshaw – Brenntag Lutterworth Ops Mgr.

Andrew Leach – Brenntag Lutterworth

Gareth Dobinson – Brenntag Leeds

Aneeb Chaudhry – Brenntag Leeds

Documentation:

1. Brenntag Clorious – Description of production process v4.0 dated 2/5/17

2. P&IDs

a. 21292-07-0001AB01 - 25M3 Multi Product Blending P&ID

b. 21292-07-0003AB01 - Fume & Dust Scrubber P&ID

c. 21292-07-0011AB01 - Multi Product Filling P&ID

3. Brenntag European HSE Manual – Standard Procedure: Handling of Clorious2 ref

HSE_SP2.05_10 rev 0 dated 22/8/14

4. Clorious Material Specifications - Sodium Persulphate, Sodium Chlorite Solutions and

utilities

5. Brenntag MSDS - Sodium Chlorite Solution 10-25% v5.1 dated 6/9/13

6. Brenntag MSDS - Sodium Persulphate v4 dated 6/7/12

Section/Stage:

The system was dealt with as 3 nodes to allow further study to sufficient detail.

Node 1: Sodium Chlorite solution addition to blending tank and filling to drum

Node 2: Sodium Persulphate solution preparation in blending tank

Node 3: Sodium Persulphate solution addition to drum to generate Clorious product

(including LEV/scrubber)

Description of operation:

The purpose of the proposed plant is to produce 0.65% Chlorine Dioxide (ClO2) in

solution by the oxidation of Sodium Chlorite solution using Sodium Persulphate solution.

There are 2 grades of Clorious 2 – 6000ppm & 2000ppm. The most common grade is

6000ppm and the quantities/concentrations quoted are for this grade.

The reaction occurs within the package that is filled (200l drum) i.e. there is no

intermediate reactor. The package is capped and left for a pre-determined period

(typically 4 days) over which the reaction occurs between the two components producing

Clorious solution. There is a unit in operation since December 2012 at Brenntag Duisburg

which was visited on the 21/7/15 to help understand better the process and potential

hazards. The visit report is in appendix 6.

Node 1: Sodium Chlorite solution addition to blending tank and filling to drum

Sodium Chlorite (approx concentration of 2.65%) is transferred from imported IBCs into

the 25m3 Multi product blending tank TK-21-001. The quantity transferred is the required

amount for the final Clorious batch. The tank has high level switching which is

interlocked to a valve in line to prevent tank overfilling. The blending tank is also

equipped with level instrumentation. The vessel is located in a bund sized for at least

110% of the contents. The blending tank is agitated when the minimum level is reached.

Approx 65 Kg of Sodium Chlorite solution is transferred to each drum via the multi-

product package filling system (Permex). This is pumped via pump P-21-001 to the drum

using a totalising mass flow meter. The addition is shutoff automatically when the 65Kg

is completed. There is also independent high level protection which shuts off the filling

system.

Node 2: Sodium Persulphate solution preparation in blending tank

Sodium Persulphate powder is used to manufacture a Sodium Persulphate solution with

warm water. The powder is dissolved in the 25m3 Multi product blending tank TK-21-

001, with agitator into deionised water, heated to 40°C. This process is endothermic with

water temperature lowering to approximately 20°C during the solutionising process. The

blending tank is located in a bund sized for at least 110% of the contents. The vessel has a

platform around the top to allow a pallet of bags to be lifted and located on the platform.

This will then allow the operator to open the manway and ‘rip and tip’.

Deionised water is pumped into the mixing vessel, through a batch meter into the mixing

tank. The blending tank has high level switching which is interlocked to a valve in line to

prevent overfilling. The blending tank is also equipped with level instrumentation.

On completion of the warm water batching, the powder is manually added to the vessel

and the mix agitated for a period of 2 hours or until the solution is clear.

Sodium Persulphate dust is not thought to present a hazard of a dust explosion. It has

been checked for the potential for a dust explosion via the German insurance database:

http://www.dguv.de/ifa/en/gestis/index.jsp and the MSDS. Both sources do not consider a

dust explosion risk to be credible.

Node 3: Sodium Persulphate solution addition to drum to generate Clorious product

(including LEV/scrubber)

Approx 143 Kg of Sodium Persulphate solution is transferred to each drum via the multi-

product package filling system (Permex). This is pumped via pump P-21-001 to the drum

using a totalising mass flow meter. The addition is shutoff automatically when the 65Kg

is completed. There is also independent high level protection which shuts off the filling

system. Only virgin drums/packs are to be used.

LEV is provided at the filling head and used to remove any potential Chlorine Dioxide

fume. Fume is extracted to a scrubber unit filled with Caustic Soda – see actions.

The following quantities are added per drum:

• 65 Kg Sodium Chlorite premix

• 143 Kg Sodium Persulphate premix

http://www.dguv.de/ifa/en/gestis/index.jsp

Each batch will be sampled and analysed to ensure that the correct quantities/

concentrations are being added (see actions)

Four drums are stored on a pallet and strapped into position – see appendix 4. The storage

location is to be determined – see actions

Any spills / wash down water is collected in a sump in the filling area. LEV is provided

above the sump in the filling area in case of inadvertent mixing of the 2 raw materials and

the generation of chlorine dioxide fume.

Chlorine Dioxide toxicity is quoted within the HSE document EH40/2005 Workplace

exposure limits:

• Long-term exposure limit (8-hr TWA reference period) – 0.1 ppm

• Short-term exposure limit (15 min reference period) – 0.3 ppm

APPENDIX 2 - HAZOP CHECKLIST

Node

See HAZOP Record Parameter Deviation

(Guide word and

parameter)

Flow No flow Less flow More flow Reverse flow Later flow Sooner flow Where else

Pressure More pressure Less pressure

Temperature More temperature Less temperature

Level Greater level Lower/less level

Viscosity More viscous Less viscous

Composition Missing

component

Extra component Different/wrong

stream

Contamination Extra phase

Sequence Step omitted Step shorter Step longer Wrong step/order

Other Start-up Shut-down Relief system Power/service

failure

Corrosion/erosion Materials of

construction

Toxic/asphyxia Maintenance

(isolation etc)

Double valves

(trapped liqs)

Valve access Instruments, trips,

testing

Fire Static electricity Noise Ionising radiations Sampling Thermal radiation Spares

What else

APPENDIX 3 - HAZOP 3 – RECORD

Date 2/6/15 & 21/7/15 & May 19

Team As front sheet

Section/Stage 1 – Sodium Chlorite solution addition to blending tank and filling to drum

Design intention

Sodium Chlorite (approx concentration of 2.65%) is transferred from imported IBCs into the 25m3 Multi product blending tank TK-21-

001. The quantity transferred is the required amount for the final Clorious batch. The tank has high level switching which is interlocked to a

valve in line to prevent tank overfilling. The blending tank is also equipped with level instrumentation. The vessel is located in a bund sized

for at least 110% of the contents. The blending tank is agitated when the minimum level is reached.

Approx 65 Kg of Sodium Chlorite solution is transferred to each drum via the multi-product package filling system (Permex). This is

pumped via pump P-21-001 to the drum using a totalising mass flow meter. The addition is shutoff automatically when the 65Kg is

completed. There is also independent high level protection which shuts off the filling system.

Guide

word

Deviation Cause Consequence Safeguards No Action

FLOW No Sodium

Chlorite

flow

Valves closed

IBC low level/empty

Batch flow meter

error

Lack of addition to

vessel and preparation

of a weak Sodium

Chlorite solution.

Batch flowmeter would

register the lack of Sodium

Chlorite addition

Vessel level would not

increase.

Less As per no flow

More

Sodium

Chlorite

flow

Human error in

adding additional

IBCs

Extra addition to

vessel leading to

overflow

Potential for increased

ClO2 generation &

operator exposure

Vessel level would show a

high level and alarm

3

Consider action of high

LS on blending tank

Reverse Not considered

credible as Sodium

Chlorite added into

the top of the mixing

vessel

Where else Leak from system Spillage to ground.

Potential splash to

operatives in area.

Oxidiser & classified

as dangerous to the

environment.

Bunded area with self -

contained effluent system.

If say spray exited from area

then leak into site surface

water system. This passes

into the site drains to an oil

interceptor before passing

through a Penstock valve pit

and into an offsite drain

7

8

Effluent system design

Emergency Plan

PRESSU

RE

More Transfer pump is

deadheaded

Potential spill – see

flow where else

Line is capable of

withstanding max pressure

Less See no/less flow

TEMP. More No issues envisaged

Less Low ambient

temperature

Potential freezing

albeit Sodium Chlorite

freeze pt. at 10-25% is

-10°C

System would be drained

when not in use and

potential freezing conditions

LEVEL High Vessel overfill due to

too much Sodium

Chlorite addition (see

more flow)

Potential overflow

into bunded area – see

flow where else

Vessel contents level alarm

Independent high level

switch

3 Consider action of high

LS on blending tank

Low See low/no flow Potential damage to

agitator if started

when not immersed

Low level interlock with

agitator

VISCOSI

TY

More No issues envisaged

Less No issues envisaged

COMPOS

ITION

Missing No issues envisaged

Extra comp No issues envisaged

Diff/wrong

stream

Potential for wrong

IBC to be positioned

Generation of ClO2

gas from mixing

vessel if acid added

Site procedures/training to

ensure close control of

incompatibles

Cont. No issues envisaged

Extra phase No issues envisaged

SEQUEN

CE

Step Omitted No issues envisaged

Step Shorter No issues envisaged

Step Longer No issues envisaged

Wrong Step/

Order

No issues envisaged

OTHER Start-up No issues envisaged

Shut-down No issues envisaged

Relief

system

Not applicable

Power/servic

e failure

No issues envisaged

Corrosion/

erosion

Potential for leak Materials considered

appropriate

Materials of

construction

Potential for leak Materials considered

appropriate

Toxic/asphy

xia

See diff/wrong

stream

Maintenance

(isolation

etc)

No issues envisaged

Double

valves

(trapped

liqs)

No issues envisaged

Valve access No issues envisaged

Instruments,

trips, testing

No issues envisaged To be part of site

systems

Fire No issues envisaged As Sodium Chlorite is

an Oxidiser if

decomposed it can

contribute to a fire.

Lack of

flammables/combustibles in

area

Static

electricity

No issues envisaged

Noise No issues envisaged

Ionising

radiations

No issues envisaged

Sampling No issues envisaged

Thermal

radiation

No issues envisaged

Spares No issues envisaged

What else No issues envisaged

Date 2/6/15 & 21/7/15 & May 19

Team As front sheet

Section/Stage 2 – Sodium Persulphate solution preparation in blending tank

Design intention. Sodium Persulphate powder is used to manufacture a Sodium Persulphate solution with warm water. The powder is

dissolved in the 25m3 Multi product blending tank TK-21-001, with agitator into deionised water, heated to 40°C. This process is

endothermic with water temperature lowering to approximately 20°C during the solutionising process. The blending tank is located in a

bund sized for at least 110% of the contents. The vessel has a platform around the top to allow a pallet of bags to be lifted and located on

the platform. This will then allow the operator to open the manway and ‘rip and tip’.

Deionised water is pumped into the mixing vessel, through a batch meter into the mixing tank. The blending tank has high level switching

which is interlocked to a valve in line to prevent overfilling. The blending tank is also equipped with level instrumentation.

On completion of the warm water batching, the powder is manually added to the vessel and the mix agitated for a period of 2 hours or until

the solution is clear.

Sodium Persulphate dust is not thought to present a hazard of a dust explosion. It has been checked for the potential for a dust explosion via

the German insurance database:

http://www.dguv.de/ifa/en/gestis/index.jsp and the MSDS. Both sources do not consider a dust explosion risk to be credible.

Guide

word


FLOW No water

flow

No Sodium

Persulphate

flow

Valves closed

Lack of supply

Batch flow meter

error

Operator failed to

add

Lack of water addition

to blending tank and

preparation of a

concentrated Sodium

Persulphate solution

Lack of addition to

blending tank and

preparation of a weak

Sodium Persulphate

solution.

Batch flowmeter would

register the lack of water

addition

Blending tank level would

not increase

Persulphate is in excess

within the drum so not

considered to be a factor on

the rate of generation of

ClO2.


not increase.

Less As per no flow

More water

flow

More

Sodium

Persulphate

flow

Batch flow meter

error or human error

in input

Human error in input

i.e. too many bags

added

Additional water

addition to blending

tank and preparation

of a weak Sodium

Persulphate solution

Extra addition to

vessel and preparation

of a concentrated

Sodium Persulphate

solution


show a high level


show a high level.

Persulphate is in excess

within the drum so not

considered to be a factor on

the rate of generation of

ClO2.


credible water added

into the top of the

mixing vessel


Potential splash to

operatives in area.

Oxidiser

Bunded area with self -

contained effluent system.








7

8


Emergency Plan

PRESSU

RE



TEMP. More Water in tank can be

> 40°C if

heater/thermostat

fails

Potential hot solution

of Sodium Persulphate

in vessel

High Persulphate

temperature is not

considered to be a

significant factor on the rate

of generation of ClO2.

Less Lack of heating

Low ambient

temperature

Potential freezing

System would be drained

when not in use and


LEVEL High Vessel overfill due to

too much

water/Sodium

Persulphate addition

(see more flow)

Potential overflow

into bunded area – see

flow where else

Vessel contents level alarm

Independent high level

switch leading to closure of

water addition valve.

Low See low/no flow Potential damage to

agitator if started

when not immersed

3 Prepare a FDS

VISCOSI

TY



COMPOS

ITION

Missing No issues envisaged


Diff/wrong

stream

Potential for wrong

bagged powder to be

positioned

Potential Safety &

Quality issues



incompatibles



SEQUEN

CE

Step Omitted Potential to not add

water or Sodium

Persulphate

See no/more flow

Step Shorter Potential to add less

water or Sodium

Persulphate

Persulphate is in

excess within the

drum so not

considered to be a

factor on the rate of

generation of ClO2.

Use of a batch meter for

water and procedures

Step Longer Potential to add more

water or Sodium

Persulphate

Persulphate is in

excess within the

drum so not

considered to be a


generation of ClO2.

Use of a batch meter for

water and procedures

Wrong Step/

Order

Potential to add

Sodium Persulphate

then water

No issues envisaged



Relief

system

Not applicable

Power/servic

e failure

No issues envisaged

Corrosion/

erosion

No issues envisaged Use of Stainless Steel

Materials of

construction


Toxic/asphy

xia

See diff/wrong

stream

Dust exposure

Extreme high

temperature i.e. can

mean Sodium

Persulphate will

decompose and emit

Sulphur oxides gases

Operator exposure can

lead to health issues

Lack of


area

Operational experience

shows that dust is not an

issue.

Maintenance

(isolation

etc)

No issues envisaged

Double

valves

(trapped

liqs)

No issues envisaged


Instruments,

trips, testing


systems

Fire No issues envisaged As Sodium

Persulphate is an

Oxidiser if

decomposed it can

contribute to a fire.

Lack of


area

Sodium Persulphate dust is

not considered to be

flammable and create an

explosion.

Static

electricity

No issues envisaged


Ionising

radiations

No issues envisaged

Sampling No issues envisaged

Thermal

radiation

No issues envisaged



Date 2/6/15 & 21/7/15 & May 19

Team As front sheet

Section/Stage 3 – Sodium Persulphate solution addition to drum to generate Clorious product (including LEV/scrubber)

Design intention. Approx 143 Kg of Sodium Persulphate solution is transferred to each drum via the multi-product package filling system

(Permex). This is pumped via pump P-21-001 to the drum using a totalising mass flow meter. The addition is shutoff automatically when

the 65Kg is completed. There is also independent high level protection which shuts off the filling system. Only virgin drums/packs are to be

used.

LEV is provided at the filling head and used to remove any potential Chlorine Dioxide fume. Fume is extracted to a scrubber unit filled

with Caustic Soda – see actions.

The following quantities are added per drum:

• 65 Kg Sodium Chlorite premix

• 143 Kg Sodium Persulphate premix

Each batch will be sampled and analysed to ensure that the correct quantities/ concentrations are being added (see actions)

Four drums are stored on a pallet and strapped into position – see appendix 4. The storage location is to be determined – see actions

Any spills / wash down water is collected in a sump in the filling area. LEV is provided above the sump in the filling area in case of

inadvertent mixing of the 2 raw materials and the generation of chlorine dioxide fume.

Chlorine Dioxide toxicity is quoted within the HSE document EH40/2005 Workplace exposure limits:

• Long-term exposure limit (8-hr TWA reference period) – 0.1 ppm

• Short-term exposure limit (15 min reference period) – 0.3 ppm

Guide

word


FLOW No Sodium

Persulphate

flow

No

extraction

system flow

Valves closed

Lack of supply

Batch meter error

Extraction fan failure

Quality issues

Potential for operator

exposure to ClO2

Batch system would register

the lack of addition

6

15

Extraction system

interlocks

Less As per no flow

More

Sodium

Persulphate

flow

Batch meter error or

human error in input

Persulphate is in

excess within the

drum so not

considered to be a

High level trip on filling

system

Extraction system to

scrubber


generation of ClO2.


credible as materials

added separately


Potential splash to

operatives in area.

Potential for localized

ClO2 generation if

both materials come

into contact

Area with self - contained

effluent system.








Sump has LEV to scrubber

system

7

8

6


Emergency Plan

Scrubber interlocks

PRESSU

RE

More Increased pressure on

transfer pump due to

dead head

Drum pressure

increases

Leak from system –

see flow where else

Potential drum failure

Pump discharge has

spillback to ensure the

material is recycled to the

tank.


TEMP. More Potential hot solution

of Sodium

Persulphate fed to

drum (see node 2)

Storage of Clorious

drums in hot ambient

conditions

Increased rate of

degradation

11

Consider package storage

location & refrigeration

Less Low ambient

temperature

Potential freezing System would be drained

when not in use and


LEVEL High Package overfill due

to too much Sodium

Chlorite/Sodium

Persulphate addition

(see more flow)

Potential overflow

into vent

High level trip on filling

system

Low See low/no flow

VISCOSI

TY



COMPOS

ITION

Missing Lack of caustic

within scrubbing

system

Release of unscrubbed

air to atmosphere

Regular checking of caustic

strength (as per site

procedures)

6

15

Extraction system

interlocks


Diff/wrong

stream

Potential for wrong

materials to be made

in vessels

Potential Safety &

Quality issues



incompatibles

Use of LEV & scrubber

system

6

Design LEV/scrubber

interlocks



SEQUEN

CE

Step Omitted Potential to not add

Sodium Chlorite or

Sodium Persulphate

Step Shorter Potential to add less

Sodium Chlorite or

Sodium Persulphate

Use of a batch meters

Step Longer Potential to add more

Sodium Chlorite or

Sodium Persulphate

Use of a batch meters

Wrong Step/

Order

Potential to add

Sodium Persulphate

then Sodium Chlorite



Relief

system

Not applicable

Power/servic

e failure

No issues envisaged

Corrosion/

erosion


Materials of

construction


Toxic/asphy

xia

See diff/wrong

stream

Generation of ClO2

and release when

changing over from

filling system to

dispensing system

ClO2 generation is

negligible at the end of

drum fill.

Extraction system to

scrubber

Maintenance

(isolation

etc)

No issues envisaged

Double

valves

(trapped

liqs)

No issues envisaged


Instruments,

trips, testing


systems

Fire No issues envisaged

Static

electricity

No issues envisaged


Ionising

radiations

No issues envisaged

Sampling Required after

approx 4 days after

drum fill to check

ClO2 content

Potential for operator

exposure

Use of sampling through

customer extraction system

12 Consider sampling

method design

Thermal

radiation

No issues envisaged



Appendix 4 – Photographs from site visit

Clorious drum showing nozzle that is used for filling/emptying

Pallet with 4 Clorious 2 drums

Appendix 5 – Past Accidents/Incidents

LPB216 Dec 2010 - Walkers fined after man killed by toxic gas

Food giant Walkers Snack Foods Ltd and chemical distributor Omnichem Ltd have been fined a

total of £350,000 after a worker died four years ago following exposure to a cloud of chlorine

dioxide fumes. The Health and Safety Executive (HSE) said that the worker was driving a lorry

containing four steel tanks, two with sodium chlorite and two containing hydrochloric acid, to the

Walkers’ site in Leicester. Both chemicals are used in Walkers’ starch reclamation unit, which

turns waste starch into food-grade material used to make snack foods. The worker inadvertently

mixed up the hoses on the tanks while transferring the two chemicals from the lorry, causing them

to produce chlorine dioxide fumes. When he realised his error, he stopped the transfer and began

to hose the area down, but he was already starting to be affected by the toxic gas. Although the

worker was taken to hospital, his condition gradually deteriorated, and he died from the effects of

the gas a month later.

The investigation uncovered a catalogue of serious failings, including:

• Insufficient written procedures for deliveries and receipt of chemicals, and insufficiently

labelled tanks.

• Employees who had tried to help did not know the type of operation that was being carried out,

nor the nature of the gas being released. They had no appropriate training and they had no idea

what to do.

• It took about an hour after the appearance of the gas cloud for Walkers to realise the severity of

the situation and evacuate employees from the area.

• There were no planned evacuation procedures for a chemical emergency at this location.

Appendix 6 Visit Report – Brenntag Duisburg 21/7/15

Hudson Consultants Ltd

511A London Road

Davenham

Northwich

Cheshire

CW9 8NA

Tel: 07879 608616

e-mail: [email protected]

Date: 24th July 2015

Company no. 5573113

VAT. No. 868395267

To: Chris Gilheaney, Rob Bagshaw,

Cc: Gareth Dobinson, Alistair Hunter

Brenntag Duisburg – Visit Note

A visit was made to the Brenntag Duisburg site on the 21/7/15 to vie the existing Clorious

production facility on the site and discuss with the site team the actions identified from the

HAZOP carried out. In addition, there were delegations from Brenntag Holland and Hungary as

they are looking to install Clorious production facilities as well.

The meeting was hosted by Dominic Schenk – Clorious Commercial Director. The Duisburg site

operational, chemistry and QA staff were also present.

Background

The production of Clorious on the Duisburg site started in December 2012. The method of

production was developed based on existing site equipment.

Summary of learning points from discussion & site visit

1. Sodium Persulphate – grade of product bought is important if the Clorious product is to be

used in drinking water

2. Sodium Persulphate – dust is not an issue. The material is granular in nature. The vessel used

for charging has limited sign of dust deposits.

3. Sodium Persulphate – heated water is added to the vessel (rather than the vessel being heated).

This just aids the dissolution of the solid into water. See actions.

4. The conductivity of the demin water used should be less than 5microS.

5. The grade of stainless steel used for the Sodium Persulphate vessel is not considered to be

important.

6. Sodium Chlorite – the minimum concentration required is 2.77% to achieve 0.65% ClO2 in

the final product.

7. Sodium Chlorite – recommend the use of HDPE as the material of construction for the vessel

– see actions

8. Sodium Persulphate & Sodium Chlorite – vessels are gravity fed into the drum/keg on a weigh

scale using batch feed systems with auto close – see actions

9. Drum customer extraction system – these are added into the drum after the 2 materials are

added. It is not considered possible to fill through this system as there is a one way valve and

also the opening would be too small and would severely limit flow.

The red cap shows the customer extraction system has

been installed.

10. Vapour extraction is used but is only required as a precaution – the filled drum was opened

and only a very faint smell could be detected

The shroud around the Sodium Persulphate fill nozzle is the

vapour extraction system. The vapours are pulled via a fan to an

alkaline scrubber which is kept at a minimum pH of 8.5 – see

actions

11. The reaction between 2.77% Sodium Chlorite and an excess of Sodium Persulphate to form

0.65% Chlorine Dioxide solution (Clorious) is slow. It is not considered to be complete before

3 days. The drums are therefore sampled and analysed on day 4 after fill to ensure reaction

completion.

12. Sampling: Each produced batch is sampled and analysed for ClO2 concentration. The first,

middle and last drums are sampled only. The sample is taken from the customer extraction

system by using a pump into a glass jar. Standard PPE and a gas mask are used during

sampling – see actions.

13. Drum storage – a container is used which is air conditioned to a temperature of 15-20°C – see

actions.

14. Accidents/Incidents – none reported. Only issue has been low batch ClO2 concentration which

has been corrected by aiming for 0.65% rather than 0.6%. Lowest observed was 0.57%.

15. Drums are laundered prior to disposal – procedure has been developed which comprises of

• Pump out residual ClO2 via customer extraction system into IBC of Sodium

Bisulphite solution

• Add water into drum via other nozzle

• Pump out until clear

• IBC starts to discolour to yellow when the Sodium Bisulphite is consumed

See actions

16. Spillage – the filling/laundry areas are contained with any spillage routed to a sump. Sodium

Bisulphite is available to treat any spillage. The effluent would be treated and sent to the site

effluent neutralisation plant.

17. ClO2 generation rate – the main factor that would probably significantly increase the initial

rate of ClO2 generation would be if concentrated Sodium Chlorite was used to feed the drum.

As 25% is imported and diluted to 2.77% then this is a credible cause – see actions.

Agreed Actions

1. Modify the P&ID/Process Description to heat the Demin water feed to the Sodium

Persulphate vessel. There should be an independent high temperature cut out on the water (set

at approx 45°C). Remove the heating element from the vessel.

2. Modify the P&ID/Process Description to show the Sodium Chlorite vessel as HDPE

3. Modify the P&ID/Process Description to gravity feed both Sodium Persulphate & Sodium

Chlorite into the drum/keg on a weigh scale using batch feed systems with auto close. The

batch weighing systems to have maximum set points allowable to limit fill quantity which

could lead to drum/keg quality issue/overfill. To allow gravity feed the vessels will have to be

supported on steelwork to give sufficient head.

4. Modify the P&ID/Process Description to include both pH monitoring of the scrubber and the

monitoring of the scrubber recirculation flow. If both are out of range (pH < 8.5 and flow <

set point to be determined) then the fill systems will not be operational.

5. Consider the methodology of sampling. There is a potential for ClO2 exposure during this

operation. Consider if there is a more inherently safe option.

6. Consider the requirement for cool storage for Clorious drums in summer

7. Develop a design for drum laundry taking into account the Duisburg experience. Things to

consider:

• Sodium Bisulphite IBC to have vapour extraction to scrubber on vent (just in case

the Sodium Bisulphite is consumed)

• Vapour extraction to be provided around where the drum is handled (as ClO2 may

be emitted from the nozzles when opened.

8. Consider the Sodium Chlorite dilution system design to minimise the potential for ensuring

that a diluted solution of 2.77% is achieved. This may include the use of a batch dilution

system that requires water to be added prior to allowing the drum fill system to become active.

It will also require sampling and lab analysis to pass off the batch prior to being used for drum

fill.

9. Extraction system – ensure that the capacity is sufficient to withdraw ClO2 vapours from the

drum nozzle which would be generated if a 25% Sodium Chlorite solution was used to fill

drums.

Conclusion

The visit was extremely useful to answer the preliminary Clorious HAZOP questions. The way

the production method has evolved were explained which will help prevent repeating past

mistakes i.e. using a vessel to store Clorious prior to filling in a drum.

HAZOP Report.pdf - Environment Agency

Documents

Transcript of HAZOP Report.pdf - Environment Agency