ballast water treatment naocl active ingredient hydrogen management discussion document rev d

BWTS NaOCl Hydrogen management of 23 ISPC © 2012

Ballast Water Treatment Systems

Electrochlorination NaOCl Active Ingredient

Hydrogen By-product Management

Discussion Document

Prepared by

Ian Perrett Consultant ISPC [email protected]

ISPC specialises as a technical consultancy service in the field of Electrochlorination Package (ECP) Engineering, primarily as utilised within Land Based and Offshore applications. As with maritime seawater system anti-fouling control Electrochlorination has been widely, safely and effectively utilised for decades in the LB and OS industries.

From published test data, marketing material and discussions viewed there

did not appear to be a wide coverage of Hydrogen by-product management available in the public domain when the electrolysis of seawater or brine solutions is utilised to supply the active ingredient of NaOCl (Sodium Hypochlorite) in BWTS’s.

This discussion document therefore endeavours to translate the principles

and understandings of Hydrogen by-product management, as applied within the LB and OS industries, to the relatively new application of ECP’s as generating systems for BWTS’s. It also addresses whether the historical experience of installation and operating of ECP’s for shipboard cooling water system fouling protection can be translated to their use for BWTS.

mailto:[email protected]

BWTS NaOCl Hydrogen management ISPC © 2012

Content 1) Electrochlorination

2) Historical Shipboard Application

3) BWTS Electrochlorination

a. Direct Injection Ballast Tank Natural Aspiration of Hydrogen By-

product

b. Indirect Injection with pre-dosing Hydrogen Dis-entrainment

4) Electrolyser Installation

5) Comments

Appendices

1) BWTS - Hydrogen Calculations Direct Injection 2) BWTs - Hydrogen Calculations Indirect Injection 3) BWTS Indirect NaOCl Injection Hazardous Area Calculations 4) BWTS Indirect NaOCl Injection Hazardous Area Calculations


1) Electrochlorination

The application of Electrochlorination is a well understood method of

controlling marine bio-fouling in a seawater system, utilising readily available seawater for partial conversion of the NaCl and H2O media by electrolysis to a low concentration NaOCl solution to accommodate the dosing requirements of the seawater system. With the advent of BWTS’s utilising this technology the question occurs whether existing electrochlorination experience in the marine environment can be applied to BWTS?

The focus of attention herein is the management of the Hydrogen generated

as one of the by-products of that electrolysis. The volume of Hydrogen by-product can be determined by a factor of 0.316 m3 @ 0°C @ 1 bara for every 1 kg of NaOCl production, the volume adjusted for the applicable design temperature.

The hypothetical examples explored within this document include:- BWT 01/02 which describes systems where a 10,000m3 ballast tank is filled at

a rate of 1,250m3/h treated to 10 mg/l NaOCl for a design ambient air temperature of 25°C.

NaOCl kg/h = (Flow m3/h x NaOCl mg/l) ÷ 1000 NaOCl kg/h = (1,250 x 10) ÷ 1000 NaOCl kg/h = 12.5 kg/h Therefore the rate of Hydrogen production can be calculated as:- H2 m

3/h = NaOCl kg/h x 0.316 x ((273 + Design Temp °C) ÷ 273) H2 m

3/h = 4.31 m3/h (355 g/h) Fill duration = 10,000 m3 ÷ 1250 m3/h Fill duration = 8 h Total H2 = 34.6 m3 (2.84kg)

2) Historical Shipboard Applications

Historically electrochlorination as a means of controlling marine bio-fouling

has largely been in the application of cooling systems water treatment. Using a side stream of the seawater system the electrolyser installation main equipment would consist of an Electrolyser assembly and a Transformer Rectifier to convert the on board AC supply utility to a DC supply for the electrolyser cells. Typically the electrolyser seawater carrier stream NaOCl discharge would be directly manifolded to the various sea chests for injection to the suction side of the seawater pumps, with flows adjusted and balanced for the fixed electrolyser mass balance of which the NaOCl production is variable by DC current control, which once set will be of a single NaOCl product concentration, i.e. production of the sum of the user weight demands with respective flow adjustment to the users.


The NaOCl dosing regime would typically be governed by monitoring the overboard discharge(s) for a trace residual chlorine concentration. This has proven adequate to ensure the seawater system as a hostile environment for marine organisms with the result that the system remains clear of marine fouling.

There are many publications that correctly identify these thousands of

installations as of proven success but can this success with cooling water treatment be wholly translated to BWTS? In a cooling water system the residence time is brief and the overboard discharge residual chlorine is not indicative of a sterile solution, it is only indicative that a trace chlorine residual exists after a brief period of time, i.e. the dosing regime does not necessarily satisfy the complete chlorine demand of the seawater. The seawater cooling system dosing regime for NaOCl is typically in the region of 0.5-1 mg/l whereas the dosing regime for BWTS is generally far higher and with much longer residence times in which the active NaOCl is effective, that dosing regime is targeted more at sterilisation which is not necessarily achieved, nor required, for once through cooling system protection from marine fouling.

Similarly Hydrogen management on historical Electrochlorination cooling

water system applications has typically been reliant on the solubility of Hydrogen in seawater maintaining the Hydrogen in solution throughout the system until it is safely released at the overboard discharge. This has been acceptable where the dosing regime and subsequent Hydrogen content is relatively low and the seawater is not exposed to atmospheric pressure and Hydrogen release within the confines of the seawater system. Again where a higher NaOCl dosing regime is employed for BWTS then the forgoing argument for Hydrogen retention as a solute would no longer be applicable.

3) BWTS Electrochlorination

Electrochlorination applied as part of a BWTS basically supplies the active

ingredient of NaOCl and the discussions herein are not related to its efficacy, they relate only to the installation and Hydrogen management where it is employed.

There are two main electrochlorination practices employed for BWTS. a) By direct injection where the electrolysis cells are configured either in the

ballast water stream or by direct injection from a seawater side stream.

b) Indirect injection by means of a side stream seawater supply to the Electrolyser assembly and introduction of an inter stage Hydrogen degassing system between the Electrolyser assembly and dosing points.

NB It should be noted that Electrochlorination systems which are also installed on FPSO’s could well be subject to existing requirements of a classified area, whether this is to a self-generated Hydrogen gas group or reflect an existing hazardous area assessment and whether that gas group classification includes Hydrogen would be considered on an individual basis..


Hydrogen as a highly flammable gas is an inherent by-product in the

electrochlorination of seawater or any brine solution. The argument that has to be considered is whether the potential exists for it to escape to atmosphere within the NaOCl generating system or application and thus self-generate a classified (hazardous) area.

Both the Hydrogen and NaOCl are generated within the electrolyser stream(s)

reaching a maximum concentration at the discharge of the electrolyser assembly. It is custom and practice to report the LEL of Hydrogen as 4% in Air, this level

is in reality the LFL with an UFL of 75%, the actual LEL of Hydrogen in Air is 17% and the UEL is 56%. Typically dilution of the Hydrogen by-product of the electrolysis of seawater is to 1% in Air by forced draught ventilation which is then considered safe to discharge into an unclassified area without changing the classification of that area.

It is generally and instinctively accepted that Hydrogen is a hazardous gas

and as a reminder of the potential hazard some of its properties are listed below Molecular weight [g/mol] 2.01594 Diffusion coefficient @ NTP (2) [m2/s] 0.61*10-4 Diffusion velocity @ NTP (2) [m/s] < 0.02 Buoyant velocity [m/s] 1.2 - 9 Specific heat (constant p) of gas @ NTP (2) [kJ/(kg K)] 14.85 gas @ STP (1) [kJ/(kg K)] 14.304 Flammability limits in air [vol%] 4.0 - 75.0 (4) Detonability limits in air [vol%] 13 - 70 (5) Minimum ignition energy [J] 1.9*10-5 for detonation ~ 10,000 Auto-ignition temperature in air [K] 793 – 1023 (858) Hot air jet ignition temperature [K] 943 Gross heat of combustion or HHV [kJ/mol] @ 15 °C 286.1 Net heat of combustion or LHV [kJ/mol] @ 15 °C 241.7 Flame temperature [K] 2318 Laminar burning velocity in air [m/s] 2.65 - 3.25 Visible laminar flame speed [m/s] 18.6 Deflagration pressure ratio 8.15 Adiabatic flame temperature [K] 2318 Detonation velocity [m/s] 1480 - 2150 Energy release [MJ/kg mixture] 2.82 TNT equivalent [g TNT/g] 26.5


a. Direct Injection Ballast Tank Natural Aspiration of Hydrogen By-product

In Land Based and Offshore applications of ECP’s Hydrogen management is

effected primarily by either forced draught air dilution (vented tanks) or by naturally aspirated (effectively open topped) Hydrogen dis-entrainment tanks before the media is utilised for dosing a seawater system. In respect of a direct injection BWTS a comparison can be drawn to naturally aspirated land based degassing tanks. A generally accepted proviso for naturally aspirated tanks would be that they have minimal ullage for Hydrogen concentration at the media surface therein and also inherit a Zone 0 C rating. The tank would typically be designed with a top cover and screened side vents to prevent wind borne debris ingress, with the side vents of equal area to the media surface to facilitate unrestricted Hydrogen escape to atmosphere and the tank physically located such that no pockets of hydrogen could be collected in adjacent structures.

However a ballast tank has a large ullage decreasing as the periodic fills

progress, arguably presenting a large but decreasing volume vented through a top vent only. The ballast tank will therefore differ by virtue of not presenting the large venting facility associated with land based naturally aspirated tanks with the Hydrogen by-product released at the rate at which it is produced into a relatively confined space. Whilst there is no forced draught air dilution there would be an exhaust by ullage air volume displacement as the ballast tank fill progresses, therefore the natural buoyancy of Hydrogen in Air has to be considered with respect to the actual Hydrogen in Air concentration that exists in the ballast tank ullage at any given time. An extract from a mathematical model BTW-02 is appended to this document which explores a theoretical equilibrium for the Hydrogen in Air concentration for a direct NaOCl injection example related to the forgoing.

Available data for Hydrogen solubility in water has been utilised and whilst

data for Hydrogen solubility in seawater is not readily available it is understood that solubility is less in chloride solutions. Again it should be appreciated that what has not been predicted in the theoretical model, based on equilibrium against solubility in a liquid mass subject to a rate of change, is the impact Hydrogen’s buoyancy in air would have through natural aspiration via the tank vents during the fill cycle.

Also an incremental theoretical model is subject to some minor inaccuracies

as the sum of the increments, particularly in the final minutes of fill where it reports increases of the Hydrogen content in excess of the actual quantity of Hydrogen produced by the electrolysis. The absolute results however correspond well with the by-product quantity calculated separately by Faradays Law. Given the forgoing argument regarding the natural buoyancy of Hydrogen in Air empirical data has also to be considered to draw conclusions on the actual hazard potential.

The theoretical model also takes into account the Hydrogen solute during the

fill cycle and that which will be dis-entrained on completion of the ballast fill cycle. Again the residence time for complete dis-entrainment on fill completion would have to be subject to empirical data as the equilibrium based model is a worst case result where continuing dis-entrainment after ballast fill completion is a function of both the Hydrogen solute and bubble rise velocity from the bottom fill.


NB. The theoretical models are based on a continuous ballast fill cycle and

consequently the continuous ullage Air/Hydrogen mixture displacement which forms part of the dilution reports of the theoretical equilibrium models. Should however a pause in the ballast fill occur then the dis-entrainment of the entrained Hydrogen and Hydrogen Solute will continue for a period of time with the probability of an increase over and above the theoretical concentrations recorded below in the absence of this displacement. A risk assessment should also consider any potential for the vents to be restricted which would similarly present the potential for an increase in Hydrogen in Air concentration within the tank.

b. Indirect Injection with pre-dosing Hydrogen Dis-entrainment

By means of an inter-stage Hydrogen disengagement system such as a

degassing tank or a hydro-cyclone assembly the electrolyser product stream is subject to entrained Hydrogen removal prior to its utilisation for dosing of the ballast water. Utilising forced draught air dilution blowers these systems are typically argued to remove 99% of the Hydrogen product from the NaOCl media. More accurately they are argued to reduce the Hydrogen in Air concentration to 1% for safe discharge to atmosphere, therefore given that the atmosphere adjacent to the media surface is 1% Hydrogen in Air a certain amount of Hydrogen will remain as a solute in the media used for dosing.

Based on this criterion an extract of a further mathematical model BWT-01,

based on equilibrium, exploring the theoretical Hydrogen in Air concentrations in the ballast tank during the fill cycle is appended. The forgoing arguments relating to the model are also applicable to this model.


4) Electrolyser Installation

The other area necessary for examination is the electrolyser installation. It

has been argued above that where there is a potential for Hydrogen to escape from the process equipment the electrolyser installation has a potential for self-generation of a hazardous area.

For the purposes of simplifying this discussion the potential for self-generation

of a hazardous area can be viewed as dependent on the NaOCl product concentration prior to Hydrogen dis-entrainment as the ratio would be consistent. In the cases discussed above this would be either from the point of production to the ballast tank in the case of direct NaOCl injection or between the point of production up to and including the Hydrogen dis-entrainment facilities.

These two cases are explored in the appended Hazardous Area

Assessments, one for each case of the above mentioned systems. These example hypothetical studies have been conducted to EN-60079-10 with similar design / operating parameters applied. The variable design conditions include the temperature which has been applied @ 55°C as a maximum, the ventilation velocity as a minimum for machinery spaces, and the pressures utilised are estimates of operating pressures at the low end of the scale. With the potential leak sized for 0.2mm2 as will be noted the hazardous area envelopes indicated vary considerably, but by this assessment they do exist.

With regard to the pressure variable utilised it has been considered that

plastic type piping would be utilised for the higher NaOCl concentrations generated by indirect injection as is standard within the industry. Careful consideration should be given to the pressure temperature relationship of these materials at the design temperature of 55°C and the potential for leakage.

In indirect systems where a degassing tank is employed the interconnecting

piping should also be assessed for similar hazards if, for example, flange connections are utilised in the interconnecting piping where the electrolyser assembly and the degassing tank are remote from each other.

Another factor for consideration where an inter stage degassing tank is

employed is the residence time the Electrolyser media discharge requires in the degassing tank for Hydrogen dis-entrainment. Typically 5 minutes this represents an H2 volume in this hypothetical example of 0.4m3 at any given time which in the event of power failure would result in its undiluted release to the discharge vent at varying concentrations of Hydrogen in Air if redundant means of dilution are not employed.

In the writers experience there has been reference made that

Electrochlorination Packages do not change an areas’ classification in which case it would be supported by Notified Body Certification to that effect. This would equally apply where an Electrochlorination Package is certified for installation in a hazardous area, but not necessarily certificated not to change that area classification if the pre-existing applicable gas group did not include Hydrogen.


5) Comments

In the LB and OS OEM supply there are differing schools of thought regarding

Hazardous area zoning of Electrolyser installations but a relatively common understanding of Hydrogen dis-entrainment tank classification.

In the cases under discussion and with regard to the Ballast Tank treatment it

is arguable that during the fill cycle that the surface of the seawater would be at least Zone 2 C based on its intermittent operation, Zone 0 C at the surface during the fill cycle. It is also arguable that the vented discharge mixture could contain a content of flammable gas above LEL and strict application could advocate a Zone 2 C rating for that area.

Given that this is a marine environment rather than LB or OS the

concentration criteria and application suggests that a different approach may be appropriate. If empirical testing suggests that a hazard presented by a theoretical model does not exist in practice then a judgement call is necessary, qualified by consideration of the forgoing arguments and any means of mitigation employed. It should be noted from the models however that a significant weight of H2 could theoretically be present in the relatively confined ballast tanks with the concentrations indicated by the equilibrium model impacted by the natural buoyancy of H2 in Air.

Whilst endeavouring to offer an objective assessment of the above mentioned

hypothetical examples this discussion document and related documents are not to be taken as ISPC advocacy of any area classification. Primarily it is an aide memoir for consideration by others to their particular project parameters.

Not dealt with in this discussion document are the subjects of corrosion and

sedimentation. The corrosive effects of the relatively dilute NaOCl media are well understood, less well understood is that for any electrolytic process is the necessity for process DC current containment to avoid media borne stray current corrosion of inline metallic piping and fittings. Similarly the electrolysis of seawater also has insoluble by-products which are typically managed by maintenance of line velocity and tank agitation to avoid their precipitation, i.e. settlement is avoided by process design.


Appendix 1


ISPC Electrochlorination Package Engineering

Title BWTS - Hydrogen Calculations Direct Injection

Document BWT 02

Revision A Date 26-Oct-12 Project Various - Marine Environment

Client TBA Page 7 of 13

Ballast Tank Atmosphere Calculations

Tank Volume 10000 m

3

Ballast Pump 1250 m

3/h 20.83 m

3/min

Duration

8.000 h 48 x 10 min increments Rate of Vent Air + H2 Discharge from Tank

= Ballast Pump 1250 m

3/h 20.83 m

3/min

Hydrogen

Hydrogen

Solute

Rate of Release 4.31 m3/h 0.072 m

3/min

as a

Hydrogen Hydrogen

Solute Solute

as a as a

Ullage Volume Volume

Volume Volume Volume Weight Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen when incremental

Increment Mins Water Ullage Hydrogen Hydrogen Conc Conc Vented Vented Ullage Solubility Volume Solute Released increase

Start m3 m

3 m

3

interval

g interval % Increase %

Cumulative

g

Increment

g

Cumulative

g g/l m3 g m

3 m

3

1 10 208 9792 0.72 59.17 0.0073% 0.0073% 1.26 1.26 59.17 0.000000 0.72 0.025 0.00

2 20 417 9583 0.72 59.09 0.0075% 0.0148% 2.54 3.80 117.00 0.000000 1.42 0.099 0.00 0.00

3 30 625 9375 0.72 59.06 0.0076% 0.0225% 3.86 7.66 173.52 0.000000 2.11 0.226 0.00 0.00

4 40 833 9167 0.72 59.00 0.0078% 0.0303% 5.20 12.86 228.67 0.000000 2.78 0.405 0.00 0.00

5 50 1042 8958 0.72 58.95 0.0080% 0.0383% 6.57 19.42 282.42 0.000001 3.43 0.640 0.01 0.00

6 60 1250 8750 0.72 58.90 0.0082% 0.0465% 7.97 27.39 334.75 0.000001 4.06 0.932 0.01 0.00

7 70 1458 8542 0.71 58.85 0.0084% 0.0548% 9.41 36.80 385.63 0.000001 4.68 1.283 0.01 0.00

8 80 1667 8333 0.71 58.79 0.0086% 0.0634% 10.88 47.67 435.01 0.000001 5.28 1.696 0.02 0.00

9 90 1875 8125 0.71 58.73 0.0088% 0.0722% 12.38 60.06 482.87 0.000001 5.86 2.172 0.02 0.01

10 100 2083 7917 0.71 58.67 0.0090% 0.0812% 13.93 73.98 529.16 0.000001 6.43 2.715 0.03 0.01

11 110 2292 7708 0.71 58.61 0.0092% 0.0904% 15.51 89.49 573.84 0.000001 6.97 3.326 0.04 0.01

12 120 2500 7500 0.71 58.54 0.0095% 0.0999% 17.14 106.63 616.88 0.000002 7.49 4.008 0.04 0.01


Hydrogen Hydrogen

Solute Solute

as a as a




Start m3 m

3 m

3

interval g interval % Increase %

Cumulative g

Increment g

Cumulative g g/l m

3 g m

3 m

3

13 130 2708 7292 0.71 58.47 0.0097% 0.1096% 18.81 125.43 658.22 0.000002 7.99 4.766 0.05 0.01

14 140 2917 7083 0.71 58.40 0.0100% 0.1196% 20.52 145.96 697.81 0.000002 8.47 5.601 0.06 0.01

15 150 3125 6875 0.71 58.33 0.0103% 0.1299% 22.29 168.25 735.62 0.000002 8.93 6.518 0.07 0.01

16 160 3333 6667 0.71 58.25 0.0106% 0.1405% 24.11 192.36 771.57 0.000002 9.37 7.521 0.08 0.01

17 170 3542 6458 0.71 58.17 0.0109% 0.1515% 25.99 218.35 805.63 0.000002 9.78 8.612 0.10 0.01

18 180 3750 6250 0.71 58.08 0.0113% 0.1627% 27.92 246.27 837.72 0.000003 10.17 9.798 0.11 0.01

19 190 3958 6042 0.70 57.99 0.0117% 0.1744% 29.92 276.19 867.79 0.000003 10.54 11.083 0.12 0.01

20 200 4167 5833 0.70 57.90 0.0121% 0.1865% 31.99 308.19 895.76 0.000003 10.88 12.473 0.14 0.02

21 210 4375 5625 0.70 57.79 0.0125% 0.1989% 34.13 342.32 921.56 0.000003 11.19 13.973 0.16 0.02

22 220 4583 5417 0.70 57.69 0.0129% 0.2119% 36.35 378.67 945.12 0.000003 11.48 15.590 0.17 0.02

23 230 4792 5208 0.70 57.57 0.0134% 0.2253% 38.65 417.32 966.34 0.000004 11.73 17.331 0.19 0.02

24 240 5000 5000 0.70 57.45 0.0140% 0.2392% 41.05 458.37 985.14 0.000004 11.96 19.204 0.21 0.02

25 250 5208 4792 0.70 57.32 0.0145% 0.2538% 43.54 501.91 1001.41 0.000004 12.16 21.219 0.24 0.02

26 260 5417 4583 0.69 57.18 0.0151% 0.2689% 46.14 548.05 1015.06 0.000004 12.32 23.385 0.26 0.02

27 270 5625 4375 0.69 57.03 0.0158% 0.2847% 48.85 596.90 1025.95 0.000005 12.46 25.714 0.29 0.03

28 280 5833 4167 0.69 56.87 0.0166% 0.3013% 51.70 648.60 1033.97 0.000005 12.55 28.219 0.31 0.03

29 290 6042 3958 0.69 56.70 0.0174% 0.3187% 54.68 703.29 1038.97 0.000005 12.62 30.913 0.34 0.03

30 300 6250 3750 0.69 56.51 0.0183% 0.3370% 57.82 761.11 1040.80 0.000005 12.64 33.815 0.38 0.03

31 310 6458 3542 0.68 56.30 0.0193% 0.3563% 61.13 822.24 1039.28 0.000006 12.62 36.944 0.41 0.03

32 320 6667 3333 0.68 56.07 0.0204% 0.3767% 64.64 886.88 1034.22 0.000006 12.56 40.322 0.45 0.04

33 330 6875 3125 0.68 55.82 0.0217% 0.3984% 68.36 955.24 1025.40 0.000006 12.45 43.976 0.49 0.04

34 340 7083 2917 0.67 55.54 0.0231% 0.4215% 72.33 1027.57 1012.58 0.000007 12.29 47.938 0.53 0.04

35 350 7292 2708 0.67 55.22 0.0248% 0.4463% 76.57 1104.14 995.47 0.000007 12.09 52.246 0.58 0.05

36 360 7500 2500 0.67 54.86 0.0266% 0.4729% 81.15 1185.29 973.76 0.000008 11.82 56.947 0.63 0.05

37 370 7708 2292 0.66 54.45 0.0288% 0.5018% 86.10 1271.39 947.06 0.000008 11.50 62.099 0.69 0.06

38 380 7917 2083 0.66 53.97 0.0315% 0.5332% 91.49 1362.88 914.93 0.000009 11.11 67.775 0.75 0.06

39 390 8125 1875 0.65 53.40 0.0346% 0.5678% 97.43 1460.31 876.84 0.000009 10.65 74.070 0.82 0.07

40 400 8333 1667 0.64 52.72 0.0384% 0.6062% 104.02 1564.32 832.13 0.000010 10.10 81.108 0.90 0.08

41 410 8542 1458 0.63 51.88 0.0432% 0.6494% 111.43 1675.75 780.00 0.000010 9.47 89.060 0.99 0.09

42 420 8750 1250 0.62 50.82 0.0494% 0.6988% 119.90 1795.65 719.40 0.000011 8.73 98.167 1.09 0.10


Hydrogen Hydrogen

Solute Solute

as a as a




Start m3 m

3 m

3

interval g interval % Increase %

Cumulative g

Increment g

Cumulative g g/l m

3 g m

3 m

3

43 430 8958 1042 0.60 49.43 0.0576% 0.7564% 129.79 1925.44 648.93 0.000012 7.88 108.792 1.21 0.12

44 440 9167 833 0.58 47.52 0.0692% 0.8257% 141.67 2067.10 566.66 0.000013 6.88 121.511 1.35 0.14

45 450 9375 625 0.54 44.67 0.0868% 0.9124% 156.56 2223.66 469.67 0.000015 5.70 137.335 1.53 0.18

46 460 9583 417 0.49 39.96 0.1164% 1.0289% 176.54 2400.19 353.07 0.000017 4.29 158.303 1.76 0.23

47 470 9792 208 0.37 30.45 0.1775% 1.2064% 206.99 2607.18 206.99 0.000019 2.51 189.647 2.11 0.35

48 480 10000 0 2.11 173.74 0.0000% 0.0000% 0.00 0.00 0.00 0.000000 0.00 0.000 0.00 -2.11

33.77 2780.92 2607.18 Max 2.11

Final Increment 48 In 1 Minute Increments

Ullage Hydrogen

Volume Volume Volume Weight Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Solute

Water Ullage Hydrogen Hydrogen Conc Conc Vented Vented Ullage Solubility Volume Solute Released

Increment Mins m3 m

3 m

3 g interval % Increase %

Cumulative g

Increment g

Cumulative g g/l m

3 g m

3

As Above 470 9792 208 0.37 30.45 0.1775% 1.2064% 206.99 2607.18 206.99 0.000019 2.51 189.647 2.11

1 471 9813 188 0.07 5.92 0.0383% 1.2447% 21.36 2628.54 192.21 0.000020 2.33 196.086 2.18

2 472 9833 167 0.07 5.92 0.0431% 1.2878% 22.10 2650.64 176.77 0.000021 2.15 203.308 2.26

3 473 9854 146 0.07 5.92 0.0493% 1.3371% 22.94 2673.58 160.59 0.000021 1.95 211.532 2.35

4 474 9875 125 0.07 5.92 0.0575% 1.3945% 23.93 2697.50 143.56 0.000022 1.74 221.092 2.46

5 475 9896 104 0.07 5.92 0.0690% 1.4635% 25.11 2722.62 125.55 0.000023 1.52 232.515 2.59

6 476 9917 83 0.07 5.92 0.0862% 1.5497% 26.59 2749.21 106.36 0.000025 1.29 246.731 2.74

7 477 9938 63 0.07 6.46 0.1149% 1.6647% 31.18 2780.38 93.53 0.000027 1.04 265.588 2.95

8 478 9958 42 0.07 6.46 0.1724% 1.8371% 34.41 2814.79 68.81 0.000029 0.77 293.712 3.27

9 479 9979 21 0.07 6.46 0.3448% 2.1819% 40.87 2855.66 40.87 0.000035 0.45 349.575 3.89

10 480 10000 2 0.07 6.46 3.5921% 5.7741% 108.14 2963.80 10.38 0.000093


Water volume = Increment Minutes x ballast Pump flow per minute

Volume Ullage = Tank volume - water Volume

Volume Hydrogen = Incremental volume of Hydrogen discharged to tank at NaOCl production rate and at design temperature - equivalent volume of solute incremental weight gain

Hydrogen Weight = Incremental weight of Hydrogen discharged to tank at NaOCl production rate and at design temperature

Hydrogen Conc. % Increase= Ullage Volume / Hydrogen volume increment discharge

Hydrogen Conc. % Cumul've= Hydrogen increment % increase + previous increment % concentration

Hydrogen Vented g increment = m3 per increment (83) x increment cumulative % concentration x Hydrogen density at design temperature

Hydrogen Vented g cumulative = Incremental vented Hydrogen weight + preceding cumulative hydrogen weight vented

Hydrogen Ullage g = Current Hydrogen Weight in current increment ullage @ current cumulative concentration

Hydrogen Solubility g/l = ((0.978 x H2 % incremental Conc)/1228)x 2.015 (Henry)

Hydrogen Volume = Ullage volume x Hydrogen cumulative % at design temperature

Hydrogen Solute = Water volume x 10^3 x increment hydrogen solubility

Hydrogen Solute m3 = Hydrogen volume at design temperature if atmosphere at 0% Hydrogen concentration

Hydrogen Solute increment m3 = Increment of Hydrogen production retained in solute and not discharged to tank during that increment


Appendix 2


ISPC Electrochlorination Package Engineering

Title BWT - Hydrogen Calculations Indirect Injection

Document BWT 01

Revision A

Date 26-Oct-12

Project Various - Marine Environment

Client TBA

Page 7 of 13

Ballast Tank Atmosphere Calculations

Tank Volume 10000 m3

Ballast Pump 1250 m3/h 20.83 m

3/min

Duration 8 h 48 x 10 min increments

Rate of Vent Air + H2 Discharge from Tank

= Ballast Pump 1250 m3/h 20.83 m

3/min

Hydrogen

Rate of Release 0.04 m3/h 0.001 m

3/min

Hydrogen Hydrogen

Solute Solute

as a as a




Start m3 m

3 m

3 g interval %

Increase

%

Cumulative

g

Increment

g Cumulative g g/l m3 g m

3 m

3

1 10 208 9792 0.01 0.65 0.0001% 0.0001% 0.01 0.01 0.65 0.000000 0.01 0.000 0.00

2 20 417 9583 0.01 0.65 0.0001% 0.0001% 0.03 0.04 1.28 0.000000 0.01 0.001 0.00 0.00

3 30 625 9375 0.01 0.65 0.0001% 0.0002% 0.04 0.08 1.90 0.000000 0.02 0.002 0.00 0.00

4 40 833 9167 0.01 0.65 0.0001% 0.0003% 0.06 0.14 2.50 0.000000 0.03 0.004 0.00 0.00

5 50 1042 8958 0.01 0.65 0.0001% 0.0004% 0.07 0.21 3.09 0.000000 0.03 0.006 0.00 0.00

6 60 1250 8750 0.01 0.65 0.0001% 0.0005% 0.09 0.30 3.66 0.000000 0.04 0.009 0.00 0.00

7 70 1458 8542 0.01 0.65 0.0001% 0.0005% 0.10 0.40 4.22 0.000000 0.05 0.013 0.00 0.00

8 80 1667 8333 0.01 0.65 0.0001% 0.0006% 0.12 0.52 4.76 0.000000 0.05 0.017 0.00 0.00

9 90 1875 8125 0.01 0.65 0.0001% 0.0007% 0.14 0.66 5.29 0.000000 0.06 0.022 0.00 0.00

10 100 2083 7917 0.01 0.65 0.0001% 0.0008% 0.15 0.81 5.80 0.000000 0.06 0.027 0.00 0.00

11 110 2292 7708 0.01 0.65 0.0001% 0.0009% 0.17 0.98 6.29 0.000000 0.07 0.033 0.00 0.00

12 120 2500 7500 0.01 0.65 0.0001% 0.0010% 0.19 1.17 6.77 0.000000 0.08 0.040 0.00 0.00

13 130 2708 7292 0.01 0.65 0.0001% 0.0011% 0.21 1.37 7.23 0.000000 0.08 0.048 0.00 0.00


Hydrogen Hydrogen

Solute Solute

as a as a




Start m3 m

3 m

3 g interval %

Increase %

Cumulative g

Increment g Cumulative g g/l m

3 g m

3 m

3

14 140 2917 7083 0.01 0.65 0.0001% 0.0012% 0.23 1.60 7.67 0.000000 0.09 0.056 0.00 0.00

15 150 3125 6875 0.01 0.65 0.0001% 0.0013% 0.25 1.85 8.09 0.000000 0.09 0.066 0.00 0.00

16 160 3333 6667 0.01 0.65 0.0001% 0.0014% 0.27 2.11 8.49 0.000000 0.09 0.076 0.00 0.00

17 170 3542 6458 0.01 0.65 0.0001% 0.0015% 0.29 2.40 8.87 0.000000 0.10 0.087 0.00 0.00

18 180 3750 6250 0.01 0.65 0.0001% 0.0016% 0.31 2.70 9.23 0.000000 0.10 0.099 0.00 0.00

19 190 3958 6042 0.01 0.65 0.0001% 0.0018% 0.33 3.03 9.57 0.000000 0.11 0.112 0.00 0.00

20 200 4167 5833 0.01 0.65 0.0001% 0.0019% 0.35 3.39 9.88 0.000000 0.11 0.126 0.00 0.00

21 210 4375 5625 0.01 0.65 0.0001% 0.0020% 0.38 3.76 10.18 0.000000 0.11 0.141 0.00 0.00

22 220 4583 5417 0.01 0.65 0.0001% 0.0021% 0.40 4.17 10.45 0.000000 0.12 0.158 0.00 0.00

23 230 4792 5208 0.01 0.65 0.0001% 0.0023% 0.43 4.59 10.69 0.000000 0.12 0.176 0.00 0.00

24 240 5000 5000 0.01 0.65 0.0001% 0.0024% 0.45 5.05 10.91 0.000000 0.12 0.195 0.00 0.00

25 250 5208 4792 0.01 0.65 0.0001% 0.0026% 0.48 5.53 11.10 0.000000 0.12 0.215 0.00 0.00

26 260 5417 4583 0.01 0.65 0.0002% 0.0027% 0.51 6.04 11.26 0.000000 0.13 0.238 0.00 0.00

27 270 5625 4375 0.01 0.65 0.0002% 0.0029% 0.54 6.58 11.40 0.000000 0.13 0.262 0.00 0.00

28 280 5833 4167 0.01 0.65 0.0002% 0.0031% 0.57 7.16 11.50 0.000000 0.13 0.288 0.00 0.00

29 290 6042 3958 0.01 0.65 0.0002% 0.0033% 0.61 7.77 11.57 0.000000 0.13 0.315 0.00 0.00

30 300 6250 3750 0.01 0.65 0.0002% 0.0034% 0.64 8.41 11.61 0.000000 0.13 0.345 0.00 0.00

31 310 6458 3542 0.01 0.65 0.0002% 0.0036% 0.68 9.10 11.61 0.000000 0.13 0.378 0.00 0.00

32 320 6667 3333 0.01 0.65 0.0002% 0.0039% 0.72 9.82 11.57 0.000000 0.13 0.413 0.00 0.00

33 330 6875 3125 0.01 0.65 0.0002% 0.0041% 0.77 10.59 11.49 0.000000 0.13 0.452 0.01 0.00

34 340 7083 2917 0.01 0.65 0.0002% 0.0043% 0.81 11.40 11.37 0.000000 0.13 0.493 0.01 0.00

35 350 7292 2708 0.01 0.65 0.0003% 0.0046% 0.86 12.26 11.21 0.000000 0.12 0.539 0.01 0.00

36 360 7500 2500 0.01 0.65 0.0003% 0.0049% 0.92 13.18 10.99 0.000000 0.12 0.589 0.01 0.00

37 370 7708 2292 0.01 0.65 0.0003% 0.0052% 0.97 14.15 10.72 0.000000 0.12 0.644 0.01 0.00

38 380 7917 2083 0.01 0.65 0.0003% 0.0055% 1.04 15.19 10.39 0.000000 0.12 0.705 0.01 0.00

39 390 8125 1875 0.01 0.65 0.0004% 0.0059% 1.11 16.30 10.00 0.000000 0.11 0.774 0.01 0.00

40 400 8333 1667 0.01 0.65 0.0004% 0.0064% 1.19 17.49 9.53 0.000000 0.11 0.851 0.01 0.00

41 410 8542 1458 0.01 0.65 0.0005% 0.0069% 1.28 18.78 8.99 0.000000 0.10 0.940 0.01 0.00

42 420 8750 1250 0.01 0.65 0.0006% 0.0074% 1.39 20.17 8.35 0.000000 0.09 1.044 0.01 0.00

43 430 8958 1042 0.01 0.65 0.0007% 0.0081% 1.52 21.69 7.60 0.000000 0.08 1.168 0.01 0.00


Hydrogen Hydrogen

Solute Solute

as a as a




Start m3 m

3 m

3 g interval %

Increase %

Cumulative g

Increment g Cumulative g g/l m

3 g m

3 m

3

44 440 9167 833 0.01 0.65 0.0009% 0.0090% 1.68 23.37 6.73 0.000000 0.07 1.322 0.01 0.00

45 450 9375 625 0.01 0.65 0.0011% 0.0101% 1.90 25.27 5.69 0.000000 0.06 1.525 0.02 0.00

46 460 9583 417 0.01 0.65 0.0017% 0.0119% 2.22 27.49 4.44 0.000000 0.05 1.824 0.02 0.00

47 470 9792 208 0.01 0.65 0.0034% 0.0153% 2.87 30.36 2.87 0.000000 0.03 2.406 0.03 0.01

48 480 10000 0 0.00 0.00 0.0000% 0.0000% 0.00 0.00 0.00 0.000000 0.00 0.000 0.00 -0.03

0.34 30.36 30.36 Max 0.03

Final Increment 48 In 1 Minute Increments

Ullage Hydrogen

Volume Volume Volume Weight Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Hydrogen Solute

Water Ullage Hydrogen Hydrogen Conc Conc Vented Vented Ullage Solubility Volume Solute Released

Increment Mins m3 m

3 m

3 g interval %

Increase

%

Cumulative

g

Increment

g Cumulative g g/l m3 g m

3

As Above 470 9792 208 0.01 0.65 0.0034% 0.0153% 2.87 30.36 2.87 0.000000 0.03 2.406 0.03

1 471 9813 188 0.00 0.06 0.0004% 0.0157% 0.29 30.65 2.64 0.000000 0.03 2.471 0.03

2 472 9833 167 0.00 0.06 0.0004% 0.0161% 0.30 30.95 2.42 0.000000 0.03 2.545 0.03

3 473 9854 146 0.00 0.06 0.0005% 0.0166% 0.31 31.26 2.18 0.000000 0.02 2.628 0.03

4 474 9875 125 0.00 0.06 0.0006% 0.0172% 0.32 31.58 1.93 0.000000 0.02 2.725 0.03

5 475 9896 104 0.00 0.06 0.0007% 0.0179% 0.33 31.92 1.67 0.000000 0.02 2.840 0.03

6 476 9917 83 0.00 0.06 0.0009% 0.0187% 0.35 32.27 1.40 0.000000 0.02 2.983 0.03

7 477 9938 63 0.00 0.06 0.0011% 0.0199% 0.37 32.64 1.12 0.000000 0.01 3.173 0.04

8 478 9958 42 0.00 0.06 0.0017% 0.0216% 0.40 33.05 0.81 0.000000 0.01 3.455 0.04

9 479 9979 21 0.00 0.06 0.0034% 0.0251% 0.47 33.52 0.47 0.000000 0.01 4.015 0.04

10 480 10000 2 0.00 0.06 0.0359% 0.0610% 1.14 34.66 0.11 0.000001


Water volume = Increment Minutes x ballast Pump flow per minute

Volume Ullage = Tank volume - water Volume

Volume Hydrogen = Incremental volume of Hydrogen discharged to tank at NaOCl production rate and at design temperature - equivalent volume of solute incremental weight gain

Hydrogen Weight = Incremental weight of Hydrogen discharged to tank at NaOCl production rate and at design temperature

Hydrogen Conc. % Increase= Ullage Volume / Hydrogen volume increment discharge

Hydrogen Conc. % Cumul've= Hydrogen increment % increase + previous increment % concentration

Hydrogen Vented g increment = m3 per increment (83) x increment cumulative % concentration x Hydrogen density at design temperature

Hydrogen Vented g cumulative = Incremental vented Hydrogen weight + preceding cumulative hydrogen weight vented

Hydrogen Ullage g = Current Hydrogen Weight in current increment ullage @ current cumulative concentration

Hydrogen Solubility g/l = ((0.978 x H2 % incremental Conc)/1228)x 2.015 (Henry)

Hydrogen Volume = Ullage volume x Hydrogen cumulative % at design temperature

Hydrogen Solute = Water volume x 10^3 x increment hydrogen solubility

Hydrogen Solute m3 = Hydrogen volume at design temperature if atmosphere at 0% Hydrogen concentration

Hydrogen Solute increment m3 = Increment of Hydrogen production retained in solute and not discharged to tank during that increment


Appendix 3


ISPC Electrochlorination Package Engineering Document BWT 05

Revision A Date 29-Oct-12 Project Electrochlorination Assembly

Client Standard - BWTS Indirect NaOCl Injection Page 3 of 7

Electrochlorination Package Data

Ambient Design Temperature

55 ºC EN DN 8861

Electrolyser Duty Streams

1.00 Qty Electrolyser Standby Streams

1.00 Qty

Electrolyser Seawater Carrier Stream Inlet Pressure 2.50 barg Electrolyser Seawater Carrier Stream Outlet Pressure 2.00 barg Electrolyser Seawater Carrier Stream Flowrate 12 m

3/h

Total ECP Flowrate

12 m3/h

Electrochlorination Package Capacity

12.50 kg/h Electrolyser Stream Capacity

12.50 kg/h

Hypochlorite Concentration

1000 mg/l Number of Electrolysers per Stream

1.00 Qty

Electrolyser Line Size

3.00 mm Leakage Orifice Size

0.20 mm

2 Standard

Leakage Orifice Diameter

0.50 mm ISO 5167-1 : 1991

Space Estimates Length

15.00 m Width

15.00 m

Height

15.00 m Occupancy

50%

Ventilation Estimate 28638 m3/h

Velocity Required (Typical)

0.10 m/sec EN DN 8861

Calculated Velocity

0.10 m/sec Air Changes per Hour (4-12 Typical)

16.97

Vz Radius

1265 mm


Appendix 4


ISPC Electrochlorination Package Engineering Document BWT 04

Revision A Date 29-Oct-12 Project Electrochlorination Assembly

Client Standard - BWTS Direct NaOCl Injection Page 3 of 7

Electrochlorination Package Data

Ambient Design Temperature

55 ºC EN DN 8861

Electrolyser Duty Streams

1.00 Qty Electrolyser Standby Streams

1.00 Qty

Electrolyser Seawater Carrier Stream Inlet Pressure 2.50 barg Electrolyser Seawater Carrier Stream Outlet Pressure 2.00 barg Electrolyser Seawater Carrier Stream Flowrate 1250 m

3/h

Total ECP Flowrate

1250 m3/h

Electrochlorination Package Capacity

12.50 kg/h Electrolyser Stream Capacity

12.50 kg/h

Hypochlorite Concentration

10 mg/l Number of Electrolysers per Stream

1.00 Qty

Electrolyser Line Size

3.00 mm Leakage Orifice Size

0.20 mm

2 Standard

Leakage Orifice Diameter

0.50 mm ISO 5167-1 : 1991

Space Estimates Length

15.00 m Width

15.00 m

Height

15.00 m Occupancy

50%

Ventilation Estimate 28638 m3/h

Velocity Required (Typical)

0.10 m/sec EN DN 8861

Calculated Velocity

0.10 m/sec Air Changes per Hour (4-12 Typical)

16.97

Vz Radius

303 mm

ballast water treatment naocl active ingredient hydrogen management discussion document rev d

Documents

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mgl naocl

naocl kgh x

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electrolysis of seawater

flow m3h x naocl mgl

available seawater