BOILER WATER TREATMENT

MARINESHELF publishes articles contributed by seafarers and other marine related sites solely for the benefit of seafarers .All copyright materials are owned by its respective authors or publishers.

What is the purpose of boiler water treatment?

(a)     To prevent scale formation in the boiler

(b)     To give alkalinity and minimize corrosion

(c)      To condition sludge (by sodium aluminate).

(d)     To remove oxygen from water.

(e)     To reduce risk of caustic cracking.

(f)      To reduce risk of carry over of foam (by antifoam)

(g)      To minimize feed and condensate system from corrosion and filming amines

The principal objects of boiler feed water treatment should be:-

          (a)     Prevention of scale formation in the boiler and feed system by

                    (i)      Using distilled water or

                    (ii)     Precipitating all scale forming salts into the form of a non-         adherent sludge.

(b)     Prevention of corrosion in the boiler and feed system by maintaining the boiler water in and alkaline condition and free from dissolved gases.

(c)      Control of sludge formation and prevention of carry over with the system.

(d)     Prevention of entry into the boiler of foreign matter such as oil, waste, mill-scale, iron oxide, copper particles, sand weld spatter etc.  By careful use of coil heating arrangements, effective pre-commission cleaning and maintaining the steam & condensate system in a non-corrosive condition.       

Boiler water should be regularly tested and the treatment of the boiler water should be conducted according to the results obtained from the results.  For low pressure boilers salinometers and litmus paper s are still frequently used as testing equipment.  For accurate testing of the boiler water, above said tests are inadequate.  Refined tests are being practiced to ascertain the exact quantity of alkalinity and salinity concentrations.

TOTAL HARDNESS TEST

Apparatus                                                              Reagents

1-Burette, automatic, 10 ml                          16 oz, bottle Versenate solution

                                                                   Ethylenedimaine Tetraacetate

                                                                    (1ml equals 1 ml as CaCO₃)

1-Evaporating Dish                                        4 oz. bottle Drew Dry total

                                                                   Hardness Buffer Reagent with plastic

                                                                   scoop

1-Cylinder, graduated,100ml capacity            4 oz. bottle Drew Dry Total

                                                                   Hardness Indicator

1-Strirring Rod                                             

1-Brass measuring scoop                                                                    

Procedure

1.       Transfer 50 ml feedwater sample to the evaporating dish.

2.       Add one plastic scoop of Drew Dry Total Hardness indicator.  Stir until dissolved.

3.       Add one brass scoop of Drew Dry Total Hardness indicator.  Stir until dissolved.

4.       If a pure blue color develops, the hardness is zero.  Any reddish color indicates hardness is present.

5.       Titrate with standard versenate solution, adding the reagent drop by drop with continuous stirring as the red color fades.  The end point is a pure sky blue color without any reddish tinge.

Calculations:

          Total hardness (PPM as CaCO3) equals ml versenate solution X 20. If test result is in excess of _____________ add ____________ B according to dosing instructions and investigate source of contamination.

ALKALINITY TEST

Apparatus

10 ml automatic burette

White porcelain evaporating dish

100ml graduated cylinder

Stirring rod

Reagents

Sulfuring acid N/50 16 oz. bottle with burette

Phenolphthalein Indicator1 oz dropping bottle

Total Alkalinity Indiacator 1 oz. dropping bottle

Procedure

A.      PHENOLPHTHALEIN ALKALINITY TEST

1.    Fill burette to 0.0 mark with N/50 sulfuric acid\

2.    Using graduated cylinder, measure 50ml of boiler water to be tested.

3.    Add 4 drops of phenolphthalein Indicator.  Stir.

4.    If no pink or red color develops, record Zero phenolphthalein alkalinity.  Proceed to Part B (Total Alkalinity test)

5.    If, however, sample turns pink or red with Phenolphthalein, add N/50 sulfuric acid drop by drop while stirring continuously.  Continue until pink color disappears (sample is back to its original color.)                                           Do not discard sample  do not refill burette

6.    Calculations of results

(Ml of N/50 sulfuric acid) X 20 = (ppm phenolphthalein alkalinity).  For convenience, use the titration chart to get result.

7.    Record the Phenolphthalein Alkalinity in the daily log and proceed with Part B

B.       TOTAL ALKALINITY TEST

1.    Do not refill burette. Use the same sample that was used for the Phenolphthalein Alkalinity test and add exactly 4 drops of Total Alkalinity Indicator.  Sample will turn a green color.

2.    Add sulfuric acid, drop by drop, stirring continuously.  A purple color will soon begin to form where the drops fall into the sample.  When a permanent, pale purple color develops throughout the sample, the test is ended.  Color change will go from green to slate gray to purple.  The purple color is the end point.

3.    Calculation of result:

(Total ml of N/50 sulfuric acid – 0.6) X 20 = ppm Total Alkalinity.   For convenience use titration chart to get results.

4.     Record the total alkalinity in the daily log.  Discard sample.

CHLORIDE TEST

Apparatus

10 ml automatic burette

White porcelain evaporating dish

100ml graduated cylinder

Stirring rod

Reagents

Mixed Chloride Indicator – Make up fresh every 4 weeks.  Discard any indicator over 4                                               weeks old

Nitric Acid N/50 1 oz. dropping bottle

Mercuric Nitrate, 0.0141 N 16 0z.bottle with burette

Preparation of mixed chloride indicator

Apparatus

100 ml  graduated cylinder

4 oz. Amber glass dropping bottle

Reagents

1 capsule of mixed chloride indicator (Diphenyl Carbazone Indicator) Methyl alcohol

(anhydrous)

Procedure

1.  Empty capsule of indicator powder into 4 oz. amber glass dropping bottle.

2.  Measure 100ml alcohol and add to bottle.

3.  Cap bottle, Dissolve powder by swirling or shaking.

4.  Make up fresh every 4 weeks.  Discard any indicator that is 4 weeks old.

CAUTION!    METHYL ALCOHOL IS POISONOUS.  DO NOT SWALLOW.  AVOID CONTACT WITH EYES

Test procedure

1. Do not use th4e sample that was used for the Alkalinity tests.  Fill burette to 0.0 mark with 0.0141 N Mercuric Nitrate.
2. Using graduated cylinder, measure 50 ml of boiler water and transfer into the evaporating dish.
3. Add 10 drops of Mixed Chloride Indicator.  Stir.
4. Add N/5 Nitric Acid drop by drop, while stirring.  Continue until sample just turns yellow.  Then add another 5 drops of the acid.
5. Add 0.0141 N Mercuric Nitrate drop by drop while stirring until the sample shows the first permanent violet color.  Read the burette.
6. Calculation of results: 

(Ml of 0.0141 N Mercuric Nitrate) X 10 = ppm Chloride.  For convenience, use the titration chart to get results.  Compare test result with limit marked on the control chart.  If too high, start continuous blowdown and investigate source.  Repeat test in 30 minutes.

7. Place the comparator base slide in its slot the base.  Move the slide form side to side, while comparing the color of the sample with those of the standards in the slide.  Continue until the color of the sample color appears to be between two standards.  In the latter case, take the average of both readings.

NOTE that a comparison can be made only when one of the white lines on the slide is opposite the middle (sample) tube.

8. When a color match is obtained, read the test result in ppm phosphate from the numbers on the slide.  Compare phosphate readings with limit marked on the control chart.  Readings in excess of limits require blowdown.  Readings below recommended limits require proportionate dosing.  Refer to dosing instructions.

If the results of the phosphate test show a reading above the upper limit of 25 ppm, it will be necessary to repeat the testing using a diluted sample.

Procedure

(1)      Filter 5 ml of boiler water into the phosphate mixing tube.  Dilute to 10 ml with distilled or demineralized* water.  Proceed with steps 2 through 8 and, for results, double the ppm reading.  (for example if slide shows 15 ppm with diluted sample, the actual reading is 30 ppm).

_*       To make demineralized water, simply fill plastic bottle with distillate and squeeze though demineralizer cartridge.  The water discharged from the cartridge will be equivalent to distilled water.

          The cartridge is good until the demineralizer beads change color as indicated in the manufacturer’s instructions.   (In the “Deem” cartridge, the color change is from blue to brown.)  When this occurs, simply replace the cartridge.

Boiler water treatment using “BOILER WATER TEST KIT (FULL SERVICE) SPECTRAPAK 311

          This test kit is for phosphate, P&M alkalinity chloride and pH.  The hydrazine is an optional extra (Spectrapak 312).

Sampling

          A representative ware sample is required.  Always take water sample from the same place.  Allow the water to flow from the sample cock before taking the sample for testing to ensure the line is clear of sediment.

Phosphate PPM PO₄

·         Take the comparator with the 10 ml cells provided.

·         Slide the phosphate disc into the comparator.

·         Filter the water sample into both cells up to the 10ml mark.

·         Place one cell in the left hand compartment

·         To the other cell add one phosphate tablet, crush and mix until completely dissolved.

·         After 10 min place this cell into the right hand compartment of the comparator.

·         Hold the comparator towards a light.

·         Rotate the disc until a colour match is obtained.

·         Record the result obtained on the log sheet provided, against the date on which the test was taken.

P Alkalinity (PPM CaCO₃)

·         Take a 200ml  water sample in the stopped bottle.

·         Add one P alkalinity tablet and shake or rush to disintegrate.

·         If alkalinity is present the sample will turn blue.

·         Repeat the tablet addition, one at a time (giving time for the tablet to dissolve), until the blue colour turns to permanent yellow.

·         Count the number of tablets used and carry out the following calculations:-

P Alkalinity, ppm CaCO₃ = (Number of tablets x 20) – 10

e.g. 12 tablets = (12 x 20)-10 = 230 ppm CaCO₃

·         Record the result obtained on the log sheet provided, against the date on which the test was taken.

·         Retain the sample for the M Alkalinity test.

M Alkalinity (PPM CaCO₃)

·         To the P alkalinity sample add one M alkalinity tablet and shake or crush to disintegrate.

·         Repeat tablet addition, one at a time (giving time for the tablet to dissolve), until the sample turns to permanent red/pink.

·         Count the number of tablets used and carry out the following calculations:-

M Alkalinity, ppm CaCO₃ = (Number of P & M tablets x 20) – 10

e.g. 12 P, and 5M.  Alkalinity tablets are used

M alkalinity = [(12+5) x 20)]-10 = 330 ppm CaCO₃

·         Record the result obtained on the log sheet provided, against the date on which the test was taken.

Chloride (PPM) Cl

The range of chloride to be tested determines the size of water sample used.  The higher the chloride level the smaller the size of water sample used – this saves tablets.

 e.g. for low chloride levels use 100ml water sample

        for higher chloride levels use 50ml water sample

·         Take the water sample in the stoppered bottle provided.

·         Add one chloride tablet and shake to disintegrate.  Sample should turn yellow if chlorides are present.

·         Repeat the tablet addition, one at a time (giving time for the tablet to dissolve), until the yellow colour changes to permanent red/brown.

·         Count the number of tablets used and perform the following calculations:-

For 100ml water sample –

Chloride ppm = (Number of tablets x 10)-10

e.g. 4 tablets = (4 x 10) – 10 = 30 ppm

For 50ml water sample –

Chloride ppm = (Number of tablets x 20)-20

          e.g. 4 tablets = (4 x 20) – 20 = 60 ppm

          For smaller steps of ppm chloride use a larger sample.

          For larger steps of ppm chloride use a smaller sample.

·         Record the result obtained on the log sheet provided, against the date on which the test was taken.

pH Test        7.5 – 14.0 For boiler water

                   6.5 – 10.0 For condensate water

·         Take a 50ml sample of water to be tested in the plastic sample container provided.

·         Using the white 0.6grm scoop provided, add one measure of the pH reagent to the water sample, allow to dissolve.  Stir if required.

·         Select the correct range of pH test strip and dip it into the water sample for approximately 10 seconds.

·         Withdraw the strip from the sample and compare the colour obtained with the colour scale on the pH indicator strips container.

·         Record the pH value obtained on the log sheet provided, against the date at which the test was taken.

Hydrazine PPM Spectrapak 312

          This is an optional extra (order Spectrapak 312).  This test must be performed below 21⁰C.  A cooling coil should be fitted at the sampling point or the sample should be cooled immediately under cold running water.  Cloudy samples should be filtered before testing.

·         Take the comparator with the 10ml cells provided.

·         Slide the hydrazine disc into the comparator.

·         Add the water sample to both cells up to the 10 ml mark.

·         Place one cell in the left hand compartment of the comparator.

·         To the other cell add one measure of hydrazine powder (using the black 1grm scoop provided) and mix until completely dissolved.

·         Wait 2 minutes and place the cell in the right hand compartment of the comparator.

·         Hold up to the light and rotate the disc until a colour match is obtained.

·         Record the reading shown as ppm hydrazine.

Safety:  These reagents are for chemical testing only.  Not to be taken internally.  Wash hands after use.  Keep away from children.

MARINESHELF publishes articles contributed by seafarers and other marine related sites solely for the benefit of seafarers .All copyright materials are owned by its respective authors or publishers.

ACCIDENTS AND FINDINGS

FIONA (31 August 1988)

The forward cargo tank of the FIONA exploded while a surveyor measured cargo temperature prior to unloading, resulting in one death. The National Transportation Safety Board (NTSB) concluded that

• A steam leak in the tank caused static charge to be generated
• The charge accumulated on an ungrounded temperature probe and discharged as the probe was withdrawn from the tank,
• The resulting sparks ignited explosive vapors from the residue of the tank's previous cargo [9].

NTSB's recommendations addressed the foregoing items and other contributory factors:

• FIONA's cargo tanks should have been inerted.
• Inert gas system (IGS) should be used with all cargoes unless tanks are gas free.
• The main source of the explosive vapors was contamination of the cargo by previous condensate cargo, while release of light hydrocarbons by the fuel oil in the tank may have been contributory.
• Masters of vessels carrying Grade E cargoes should certify that explosive vapors are not present prior to sampling or measuring cargoes with a combustible gas indicator device.
• The static charge was generated by a steam leak in the cargo heating pipes and accumulated on an ungrounded temperature probe. Better maintenance might have prevented the casualty. · The probe lacked a precautionary nameplate stating the, need for grounding the instrument during use. Underwriters Laboratory UL) should adopt the Canadian Standards Association requirement for such a nameplate. The internal grounding wiring on these probes should also be checked periodically.

AMERICAN EAGLE (26, 27 February 1984)

The AMERICAN EAGLE, sailing in ballast, exploded and sank in the Gulf of Mexico with the loss of four lives. The NTSB concluded that the most probable cause of the explosion was the use of a steam powered air ventilator fitted with a long plastic sleeve in a non-gas free tank

The ship had been carrying fuel oil and gasoline. The tank in question had been washed, but not gas freed; an explosive mixture in the tank was possible.

The probable cause of ignition was an incentive spark between the tank structure and charged steam condensate falling from the plastic sleeve through which the air was being driven.

The crew was unaware of the clear warning against the introduction of steam into potentially explosive atmospheres. The use of non-conductive material contributed to the accumulation of static charge.

As a result of the accident, NTSB recommended that "A Manual for the Safe Handling of Flammable and Combustible Liquids and Other Hazardous Products", be revised to thoroughly address static electricity hazards on tank vessels.

 

MARINESHELF publishes articles contributed by seafarers and other marine related sites solely for the benefit of seafarers .All copyright materials are owned by its respective authors or publishers.

Hypothermia

Key points

• Hypothermia is defined as a core body temperature below 35ºC (95ºF)
• Suspect toxic, metabolic, or endocrine etiology in patients who present with hypothermia without a history of environmental exposure
• Initial management includes rewarming, cardiopulmonary and hemodynamic stabilization, trauma assessment, finger stick for blood glucose determination, blood tests to assess patient's general biochemical and physiologic status, and an electrocardiogram (ECG) and cardiac monitoring to identify arrhythmias
• Rewarm at rates of 0.5ºC to 2ºC per hour (0.9ºF-3.6ºF/h) using one or more rewarming techniques, including passive external rewarming with removal of wet clothing and wrapping in warm blankets; active external rewarming with hot water bottles and other devices; active core rewarming via airway and heated body cavity irrigation; and extracorporeal blood rewarming via cardiopulmonary bypass
• Patients with severe hypothermia (<30°C or 86°F) are at risk of ventricular arrhythmias and require more rapid rewarming with active internal rewarming techniques
• Monitor patient during active core warming for dysrhythmias or vascular collapse
• Cardiac drugs and defibrillation are generally less effective or ineffective in the presence of acidosis, hypoxia, and hypothermia
• Patient movement should be kept to a minimum as it can lead to dysrhythmias
• Patients with severe hypothermia may appear to be dead, but should be rewarmed before terminating resuscitative efforts. Due to vasoconstriction and profound bradycardia that can be seen in severe hypothermia, palpating pulses can be difficult
• Hypothermia induces a neuroprotective state, and there are many case reports of patients surviving prolonged resuscitation attempts

Background

Description

• Hypothermia is defined as a core body temperature below 35ºC (95ºF)
  • Mild: 35ºC to 32ºC (95ºF-90ºF)
  • Moderate: 32ºC to 30ºC (90ºF-86ºF)
  • Severe: below 30ºC (<86ºF)
• Classification by temperature is not universal and actual temperature cut-offs vary by source
• The body has a limited capacity to increase heat production, and hypothermia occurs when heat loss is greater than heat production
• Hypothermia can be considered:
  • Primary due to straightforward exposure to cold environments
  • Secondary due to disease or an environmental exposure coupled with another reason, such as intoxication
  • Intentional as in cardiac bypass or post-resuscitation therapeutic hypothermia
• Hypothermia affects all organs of the body; minor deviations from normal temperature can lead to clinically significant dysfunction
• Absence of respiratory and cardiac function may return as patients are rewarmed

Epidemiology

• Varies widely depending on location and season
• Estimates are difficult to quantify as hypothermia is often listed as a secondary diagnosis
• 0.3/100,000 deaths from primary hypothermia
• Extremes of age (young children and the elderly) are the most vulnerable to hypothermic injury
• Adults have highest probability of being exposed to hypothermic conditions
• Males more affected than females
• In urban populations of the U.S., most cases of hypothermia are due to homelessness, mental illness, or illicit drug and/or alcohol use
• Outdoor workers are at increased risk
• Poverty may be associated with inadequate indoor heating and poor clothing and predispose to climate-related hypothermia

Causes and risk factors

Causes:

• Decreased heat production:
  • Nutritional depletion: malnutrition, hypoglycemia, extremes of age (the very young and the very old)
  • Endocrine disorders: hypopituitarism, hypoadrenalism, hypothyroidism
  • Neuromuscular dysfunction: impaired shivering, immobility
• Increased heat loss:
  • Environmental exposure: trauma, mental illness, disorientation, suicide, myocardial infarction, recreational exposure such as skiing or mountain climbing
  • Drug intoxication: alcohol, toxins, sedative/hypnotics, narcotics, barbiturates
  • Skin disorders: burns
  • Iatrogenic: prolonged cardiopulmonary resuscitation (CPR), postsurgical, therapeutic, cold intravenous fluids, overcooling of patients with heat stroke
• Impaired thermoregulation:
  • Central: spinal cord injury, cerebrovascular accident
  • Peripheral: neuropathy, diabetes
  • Metabolic/toxic: drugs (benzodiazepines, phenothiazines, tricyclic antidepressants, barbiturates, lithium, clonidine), anorexia, diabetic ketoacidosis, hepatic failure, uremia, lactic acidosis, hypoglycemia
• Miscellaneous:
  • Sepsis: Gram-negative sepsis, meningitis
  • Pancreatitis
  • Uremia
  • Vascular insufficiency
  • Carcinomatosis
  • Seizure disorder
  • Peritonitis

Risk factors:

• Age: Mild hypothermia is more common in the elderly because of comorbidities, medications, reduced metabolic rate, and immobility. Elderly patients may have poor nutrition or be challenged by poverty resulting in inadequate heating
• Arterial disease
• Diabetes mellitus (type 1 or type 2)
• Altered mental status
• Homelessness
• Drug use (licit and illicit)

Screening

Summary approach

Not applicable.

Primary prevention

Summary approach

• Limit exposure to cold environmental temperature
  • If hypothermia is due to inadequate housing, clothing, or heat source, refer patient to social services
  • Extremes of age and those patients with medical, nutritional, or another propensity for hypothermia should be extra vigilant in minimizing cold exposure
• Avoid alcohol and illicit drugs during periods of cold exposure. Abstinence from alcohol and illicit drugs will minimize cases of hypothermia
• Satisfy fluid and nutritional requirements; correct dietary deficiencies