GROUP 4-5CHEA

I. INTRODUCTION

Unilever Philippines1351 United Nations Ave, Manila

Unilever is an Anglo–Dutch multinational company, which is one of the world’s leading suppliers of fast consumer goods sold in over 190 countries and used by 2 billion consumers everyday.

HISTORY

Unilever wasn't formed until 1930, the companies that joined forces to create the business we know today were already well established before the start of the 20th century.

Unilever's founding companies, Lever Brothers and Margarine Unie produced products made of oils and fats, principally soap and margarine. Since palm-oil was the major content of production for soap and margarine, they agree to merge - and so Unilever is created. Their merger made them import more Palm oil efficiently.

MISSION

“Unilever's mission is to add Vitality to life. We meet everyday needs for nutrition, hygiene and personal care with brands that help people feel good, look good and get more out of life.”

VISION

To develop new ways of doing business that allows business growth whilst reducing the operations’ environmental impact.

Corporate Responsibility

“To succeed also requires, we believe, the highest standards of corporate

behaviour towards everyone we work with, the communities we touch, and the

environment on which we have an impact.”

Eco-efficiency – reducing the impacts of their operations Eco-innovation – reducing the impacts of their products Sustainability programmes in agriculture and water

II. UNILEVER’S NEED FOR BOILER

Unilever’s Brands are divided into 3 Major Categories

1. Food and Drink2. Home Care3. Personal Care

Almost all of the products under each category use steam for their production to be made possible. Some of the use of steam is discussed.

1. Food and Drink

Steam is used for

Lipton juices-powder drying

Knorr-Steam Evaporators for Crumb Manufacture

Knorr- Steam injection for cooking sauces, soups, ready meals

Lady’s Choice-Steam for pulling vacuum in jars, cans, bottles

Royal-Pasta extrusion process

2. Home Care

Steam is used for

Surf/Domex-Saponification

Surf-Sulphonation

Surf/Domex-Superheated Drying

3. Personal Care

Steam is used for

Vaseline/Dove-Heating jacket in a mixing vessel for shampoo production

Cream Silk/Dove-Steam (for wax removal) Rexona-Steam heat is applied to melt the ingredients for deostick

production

III. BOILER DESCRIPTIONS

SpecificationsThe boiler used by Unilever Philippines is a Cleaver-Brooks Model CBLE Boiler.

It was installed last 2010 and has a model number of CBLE – 100 – 350 – 250 ST and a serial number of T1901 – 1 – 1. CBLE Boiler is a packaged fire tube boiler, and the fuel used in it is an Automotive Diesel Oil (ADO) with 2% CME from Petron.

Unilever’s boiler can produce 12,075 pounds of steam per hour, and it uses its fuel at a rate of 102.1 gallons per hour. The pressure and superheat temperature is at 5 psi and 115˚C respectively. It includes the four-pass dryback design and 5 ft2 of heating surface per boiler horsepower. In addition to the features of the boiler, the manufacturer claims that it has low emission. Cleaver-Brooks' commitment to lowering emissions is based on more than 400 low NOx installations - all passing guaranteed emission performance levels.

For the power requirements, the boiler, the oil pump motor, and the air compressor operates at 350, ¾ and 5 horsepower respectively.

IV. Fuel CharacteristicsA diesel laboratory test report last July 14, 2012 was presented to the group

during the visit in Unilever. It shows that the fuel passed the standard. The results of the test were shown in the table below. While the ultimate analysis of the fuel shows that it contains 85.8% Carbon, 12.7% Hydrogen, 0.03% Sulfur, 0.3% Ash and 0.01% moisture.

Parameters Result StandardAppearance clear ClearDensity at 15˚C 847.7 kg/m3 820 – 860 kg/m3

Flash Point 78˚C 55˚C minKinematic Viscosity at 40˚C

3.63 cS 2 – 4.5 cS

Viscosity at 100˚F 39.3Heating Value 19 420 BTU/lbSediments and Water 0.005% vol 0.1% vol maxSulfur 0.03% 0.05% maxMoisture Content 0.01% 0.05% maxFAME Content 2.1% vol 1.7 – 2.2 % volMethyl Laurate Content 1% mass 0.80% min

V. Operating Conditions

Unilever has a boiler log sheet where they record the boiler’s operating conditions every hour. The boiler log sheet last September 11, 2013 is shown below. It can be seen the pressure of the boiler ranges from 169 to 174 psig, the atomizing pressure ranges from 13 to 17psig, and the fuel pressure ranges from 47 to 48 psig. The flue gas temperature also ranges from 390 to 430˚C. The firing rate of the fuel also ranges from 35 to 50% firing. The feed water pressure pump is constant at 17 bar. The steam pressure and water temperature in the deaerator were also constant at 5 psig, and 115˚C.

TimeBoiler

PressureAtomizing Pressure

Fuel Pressure

Flue Gas Temperature

Firing Rate

(psi) (psi) (psi) (˚C) (%)6:00am 172 16 49 400 457:00am 171 17 47 420 508:00am 173 14 48 400 409:00am 169 13 48 430 5010:00am 174 13 47 400 3011:00am 172 14 48 390 35

Time

Feed water

Pressure Pump

Feed WaterFlow Meter

Fuel Meter

DeaeratorSteam meter

SteamPressur

e

WaterTemperatur

e

(bar) (m3) (psi) (˚C) (kg)6:00am 17 8997.1 939009 5 115  

7:00am 17 9000.8 929070 5 1159187652.

2

8:00am 17 9003.4 933143 5 1159189948.

69:00am 17 9005.8 929234 5 115 9193986

10:00am 17 9007.7 939279 5 1159194577.

4

11:00am 17 9012.4 939327 5 1159196643.

2

Chemicals were also used to treat the feed water of the boiler. Unilever uses two chemicals to treat their feed water. These two are the NexGuard 22310 which is a boiler water internal treatment, and the other one is NALCO 780 which is a liquid oxygen scavenger. The NexGuard that they were using will expire on October 5, 2014. It was tested last Oct 5, 2012 and shows that its appearance passed the standard which is golden – orange fluorescent liquid. Its specific gravity at 25˚C is 1.184, and a pH of

10.60 at 25˚C. While their oxygen scavenger will expire on September 14, 2014. It was tested last September 14, 2012 and shows and appearance of clear very light pink liquid. Its standard should be light orange to amber liquid, clear to slightly hazy, turning to light pink w/ age. Its specific gravity at 25˚C is 1.33. An analysis of the flue gas was also presented, and it shows that the flue gas contains 13.64% CO2, 11.36% O2, and 75% N2. And it was recorded that Unilever’s boiler has an efficiency of 82.5%.

VI. Operational Issues

• Instrument Failure

o Low water level in deaerator

• Power Failure

VII. Current BAT/BEP Practices

• Metering to monitor boiler efficiency

• Water treatment

• Installation of automatic blowdown system

• Plant scheduling and boiler optimisation to maximise plant efficiency

VIII. Environmental Issues

Gas Emissions

No. 2 Fuel Oil, 15% excess air

No. 6 Fuel Oil, 15% excess air

Natural Gas, 15% excess air

Air Pollutants

Carbon Monoxide

• formed from the incomplete combustion of fuel and photochemical reactions in the atmosphere

• bind with oxygen in the bloodstream

• its effects are dependent on the concentration and duration of exposure

• short-term exposure causes nervous system, cardiovascular, respiratory problems

• long-term exposure causes nervous system, developmental, adverse birth effects, death

• oxygen should be continually monitored and maintained at an acceptable concentration level based on performance test results to prevent carbon monoxide formation

NOx

• formed when high flame temperatures cause nitrogen molecules from air to break apart and combine with oxygen

• if small particles penetrate deeply, it causes emphysema, bronchitis

• aggravates heart disease

• flue gas recirculation from the boiler outlet, steam or water injection, standard size combustion air fan for induced flue gas recirculation should be applied to prevent NOx formation

• maintain stable combustion at lower flame temperatures to prevent NOx formation

SOx

formed from the incomplete combustion of fuel

• short-term inhalation causes narrowing of the airways leading to increased asthma symptoms

• if small particles penetrate deeply, it causes emphysema, bronchitis, heart disease

Hydrocarbons

• benzopyrene is the most common

• formed from the incomplete combustion of fuel

• found in diesel particles, soot

• causes skin disease (eczema, psoriasis), developmental, immunological damage, cancer

Particulate Matter

• complex mixture of extremely small particles and liquid droplets

• causes irritation of the airways, coughing, difficulty to breathing, decreased lung function, asthma, chronic bronchitis, irregular heartbeat, heart attacks

• cyclone separator is used to prevent particulate matter pollution

Water Treatment

Boiler Water Internal Treatment-NexGuard 22310

• blended corrosion inhibitor

• solution of polymers, phosphonate, chelant, residual phosphate

• has resistive degradation in the presence of oxygen

• can handle different temperatures

• long retention time

• makes impurities soluble to prevent scale, deposition, corrosion and carryover prevention which reduces blowdown

• cleans feed water, internal boiler surfaces, condensate return

Liquid Oxygen Scavenger-NALCO 780 & Deaerator

• prevents oxygen-induced corrosion

• standard level of dissolved oxygen is less than 20 ppb

• sodium sulfite (Na2SO3) is used as the oxygen scavenger

Sound Emissions

• complies with American Boiler Manufacturers Association Test Code for the Measurement of Sound from Packaged Boilers, and American National Standards Institute

• minimum of 85 decibels

• measured 4.5 feet above the floor and 3 feet horizontally from each surface of the smallest imaginary rectangular box which could completely enclose the entire unit which contains the sound source

• dependent on boiler location, motor type, altitude, sound meter

• planting bushes and trees, regular servicing and tuning of boilers, putting of noise absorbing material for the walls, windows and ceilings, using of ear plugs and earmuffs and conducting social awareness programs prevents noise pollution

Boiler hp

125 150 200 250 300 350 400 450 600 700 750 800

High-Fired Oil

[db]

84 84 84 83 84 85 84 85 85 88 89 90

Low-Fired Oil

[db]

82 82 83 81 82 83 82 83 83 84 87 89

High-Fired Gas

[db]

82 82 83 82 83 84 83 83 85 87 89 90

Low-Fired Gas

[db]

81 81 82 81 82 83 81 81 82 84 86 88

IX. BAT/BEP Using FireCAD

USING BOILER SPECIFICATIONS IN FIRECAD

Efficiency computed using FireCad on the current boiler specification is 94.64%

1) Forced Draft Burner Proper Care

From the boiler specifications given to us by Unilever, it was suggested by the

manufacturer that 15% of excess air be used if Fuel No. 2 is used in the boiler. From

literature, it is said that properly operated boilers require a certain amount (10% to 20%)

of excess air to ensure complete combustion.

Unilever’s boiler uses forced draft burners to supply air for combustion, which is

an automatic combustion control system, that monitor flue gas combustion and adjust

combustion air quantities on instantaneous basis. The fan on a burner moves a

constant volume of air, not molecules. Any change in temperature or barometric

pressure causes a change in the number of air molecules that the fan moves. The

group suggest that proper care be given to this forced draft burner so as to prevent

manual adjustment on the excess air needed by the fuel fired to the boiler.

2) Condensate Return

The condensate from a steam boiler

system is hot mineral-free water. To

minimize the use of cold makeup water

which must be heated prior to entering the

boiler, consideration on the use of

condensate return should be noted by

Unilever.

The use of condensate return would

decrease the use of chemicals and will

improve boiler surfaces. This will further

reduce corrosion, which can lead to early failure, and the buildup of scale, which can

lower boiler efficiency.

3) Blowdown Heat Recovery

Efficiency Improvement - Up to 2 percentage points.

According to the boiler operator, blowdown from their blower is sent directly to

the sewers, this means that the heat contained in the water removed through blowdown

go down the drain. The energy contained in blowdown can be further used to preheat

feed water and supply flash steam required by deaerator.

This could be done by installing a heat exchanger in the blowdown line, which

will allow this waste heat to be used in preheating makeup and feed water. Heat

recovery is most suitable for continuous blowdown operations which in turn provides the

best water treatment program.

4) Exhaust Heat Recovery

Installation of an economizer in Unilever’s

boiler is suggested since the boiler’s flue gas

temperature is in the range of 390-420℃ . Useful

energy still exists in the flue gas and as

suggested by UNEP if stack temperature is more

than 200℃ waste heat recovery is suggested.

An economizer can be attached to the flue to

recover a portion of the exhausted heat. This heat

can be used to preheat boiler make-up water. Extreme care not to extract so much heat

should be done so as to prevent condensation of the flue gas which would cause

corrosion.

Adding an Economizer could raise the efficiency to 95.63% which is higher than the

computed efficiency of the current boiler which is 94.64%

5) Preheat Combustion Air

Efficiency Improvement - Up to 1 percentage point.

Air used by the boiler may be preheated if its intake location and the ceiling of

boiler room have large temperature differences. Since insulation is very minimal in

Unilever’s boiler room, the hot air could be a result of boiler and stack losses. The boiler

efficiency could be increased by either extending the intake upwards or forcing the hot

air down but both of these options require a fan and ductwork. If hot air is proven to be

due to boiler wall losses, insulation around the boiler may be a better way of increasing

its efficiency.

6) Turbulators and soot blowers

Efficiency Improvement - Up to 2 percentage

points.

From the boiler’s specifications provided to

us. Unilever’s boiler doesn’t have any turbulators

nor soot blowers. Turbulators are metal baffles

inserted into fire tube boilers which is used to

increase the heat transfer by increasing the

surface area and slowing down the compressed air to help keep the fire-side surface of

solid fuel or oil fired boilers clean.

7) Fit Pipe Lagging (Pipe insulation)

As the group noticed, Unilever’s pipes were not insulated, and according to the

boiler’s operator we have talked to, to prevent steam, they have to produce steam which

has a higher temperature than what is needed by the facility, that needs the steam they

produce. Unilever should consider insulating their boiler’s surfaces such as pipes,

flanges and valves which are hotter than 50˚C as heat losses contribute directly to

carbon emissions, energy use and steam lost to condensation.

Lagging or pipe insulation can significantly reduce thermal losses resulting in less

energy, carbon emissions and water use as there is less steam lost to condensation.

Heat losses also increase ambient temperature and impact upon other equipment,

especially cooling systems which have to work harder, and staff working conditions

which become uncomfortable.

8) Consider using Natural Gas as substitute for Fuel No. 2

From the specifications given to the group, Unilever’s boiler is specially made for Oil

and Gas firing. Natural Gas is cheaper and more environmental friendly compared with

oil as fuel for burners. The disadvantage of using Natural Gas is that more energy is

wasted in the stack gas, to prevent this waste, the group has suggested earlier using an

economizer to prevent such losses if Natural Gas is used with Fuel No. 2.

Adding an Economizer and using Natural Gas as a substitute for Fuel No. 2 could raise the efficiency to 95.51%, though lower compared with using Fuel No. 2.(95.63%), Natural

Gas is more emission compliant compared with Fuel No.2.

X. Summary of Observations

• The boiler that we examined is a packaged firetube boiler of welded steel construction and consists of a pressure vessel, burner, burner controls, forced draft fan, damper, air pump, refractory, and appropriate boiler trim.

• Firetube boilers are available for low or high pressure steam, or for hot water applications. They are typically used for applications ranging from 15 to 800 horsepower.

• Because of its vessel size, the firetube contains a large amount of water, allowing it to respond to load changes with minimum variation in steam pressure.

• The primary purpose of the boiler is to supply energy to the facility’s operations - manufacturing processes.

• The boiler never stopped its operation since it was bought in 2010.

• Its first major inspection is on December, 2013.

• The boiler uses diesel fuel instead of bunker fuel for it to be approved and be given a permit to operate for the flue gas of a bunker fuel has a high sulfur content compared with the 0.03% sulfur content of the diesel fuel.

• Their fuel tank capacity is 38 tons. Petron is their supplier of diesel fuel with 20 tons per delivery.

• The pipes where the steam flows have metal coating to prevent the pressure and temperature from decreasing.

• The boiler blowdown go straight to the sewer.

• They have 2 tanks for water softening treatment . When one is being used the other one is being regenerated.

• Excessively hard water will nearly always have to be softened in order to protect the water piping systems.

• At a hardness of greater than 300 mg/L as calcium carbonate, scale will form on pipes as calcium carbonate precipitates out of the water.  The scaling can damage equipment and should be avoided. 

• They use NaCl as water softening agent. The water is treated before it enters the deaerator.

*A deaerator is a device that is widely used for the removal of oxygen and other dissolved gases up to level of 7ppb or 0.005 cm3/L. Dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust).

Recommendations

• It is recommended that a boiler room log or record be maintained. Recording of daily, weekly, monthly and yearly maintenance activities and recording of any unusual operation will serve as a valuable guide to any necessary investigation.

• Costly down-time or delays can be prevented by systematic checks of actual operation against the normal sequence to determine the stage at which performance deviates from normal.

*Knowledge of the system and its controls will make trouble shooting much easier.

• The waterside condition of the pressure vessel is of extreme importance. Waterside surfaces should be inspected frequently to check for the presence of any mud, sludge, scale or corrosion.

There are a few basic steps that can be taken to optimize the efficiency of boilers.

• Step 1: Stop Water Leaks- Significant water, energy and heat can be lost due to leaks in boiler and pipe systems.

• Step 2: Fit Pipe Lagging (Pipe Insulation)- Lagging or pipe insulation, when correctly applied,

can significantly reduce thermal losses resulting in lessenergy, carbon emissions and water use as there is less steam lost to condensation.

• Step 3: Improve Feed Water Quality- Clean water will mean less blowdown is required to prevent scale, fouling, corrosion and blockages.

• Step 4: Fix Steam Traps- When steam traps fail they will either stick open or shut, both of which degrade performance and increase fuel and water use.

• Step 5: Return and Reuse Condensate- This water is already hot and demineralised and therefore requires less energy to boil than the feed water and requires no treatment, saving on fuel and chemical costs.

• Step 6: Reduce and Reuse Blowdown- Reducing blowdown reduces energy, carbon

emissions, heat losses, water treatment costs and water consumption.

• Step 7: Reuse Water- Blowdown water can be used for other purposes withinthe facility where the heat and pressure is useful and the application is not sensitive to the higher concentration of solids.

Acknowledgements

Unilever Philippines1351 United Nations Ave, Manila-company visited

Certified Boiler Operator: Engr. Augusto Bawar

References:

5 Minute Guide. www.pacia.org.au/DownFile.Aspx?fileid=1300. Date Retrieved: September 18, 2013.

Question & Answer

1. How much is the new efficiency when economizer was added to the boiler system? 90-91%

2. Give one facility of Unilever that uses the steam generated by its boiler? personal care, home care..etc..

3. True or False. One of the BAT/BEP practiced by Unilever is metering to monitor boiler efficiency. True

4. Which is the largest pollutant emitted for using No. 2 fuel oil?

A. SOx

B. Hydrocarbons

C. Particulate Matter

D. Carbon Monoxide

5. Which of the following are the operational issues encountered by the boiler?

A. power failure

B. instrument failure

C. all of the above

D. none of the above

6. True or false, maintaining stable combustion at lower flame temperatures prevents NOx formation. True

7. What is the type of fuel used in the boiler?  fuel no. 2 or automotive diesel oil

8. What is the water softening agent that the boiler use? NaCl

9. What is an unacceptable boiler capacity for a firetube boiler?

a. 1000 hp c. 300 hp

b. 500 hp d. 15 hp

10. What type of boiler is used? Packaged Firetube Boiler