BOILER PRINCIPLES

Highlights

1. Definition boilers & steam forming process

2. Type boiler combustion system based

1. Furnace bed material
2. Excess / shortage of type-type boiler

3. System maintenance boiler

1. New Boiler / renovation
2. Routine care (internal)

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OPERATION OF VACUUM SYSTEM

3.6.1 Start Vacuum System

To arouse a vacuum in the evaporator used a tool called Ejector.

If  Black Liquor is charged each effect and Cooling water was circulated on Surface condensers and after / inter condenser, the vacuum system can be operated with the following procedures:

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BBM STILL AGAINST OVERWHELMED WHATSAPP

BlackBerry Messenger ( BBM ) app store may be topping the App Store and Google Play Store to subvert its competitors , WhatsApp . But actually , WhatsApp still excel far above the fuel .

WhatsApp now is cross- platform messaging service that is most widely used . CEO WhatsApp , Jan. Koum , stating that WhatsApp active users has reached 350 million .

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SAMSUNG PREPARE GALAXY S4 ACTIVE MINI VERSION

Variants of the Galaxy S4 would soon be increased . Because , Samsung reportedly is reportedly preparing another mini version of the flagship smartphone in the series GT - I8580 .

So , what's the difference with the Galaxy S4 Mini that was first marketed ? As quoted from Phone Arena , Wednesday ( 30/10/2013 ) , the GT - I8580 reportedly is a mini version of the Galaxy S4 Active . That is , the Galaxy S4 Active Mini version is supposedly also going to have the ability to withstand water and dust .

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DRINKING DRUGS CAN BE DEADLY BY ORANGE JUICE

Eating grapefruit and some other citrus fruits are known to cause adverse reactions when combined with certain medications. The most recent research indicates, this risk is far greater than previously thought.

Research published in the Canadian Medical Association Journal stated, grapefruit and some other citrus fruits can cause death, acute renal failure, failed lungs, intestinal bleeding, and other serious health problems due to interactions with certain drugs.

A total of 85 drugs reported to interact with grapefruit, and 43 of which can cause serious side effects.
This reaction is due to the active ingredients in fruit that is a compound called furanocoumarin inhibit the action of enzymes in the body. In addition, these compounds can also increase the dose of the drug to be several times as much, which can cause overdose. In addition to grapefruit, other citrus fruits such as lemons and oranges also contain a compound furanocoumarin byword.

Drugs that can interact with other compounds in grapefruit include anti-hypertensive drugs, anti-cancer drugs and anti-cholesterol drugs.

Dr.. David Bailey, a Canadian scientist says, "although side effects are harmless enough, but grapefruit can also help to a certain type of treatment. But recently claimed discovery of the negative effects of grapefruit on drugs increased from 17 to 43 drugs during 2008 to 2012. This makes the increase is more than 6 drugs per year. "
Bailey added, "current knowledge about drug and food interactions are still lacking, both healthcare practitioners and patients."

For drugs with a low effect, furanocoumarin can increase the effect. But for drugs with effects already high, furanocoumarin instead will lead to over dosage up to 330%.

Dikarena the high risk in using grapefruit or other citrus in raising the dose of medication, then its use can not be done in general practice. "Understanding is very important, so that both doctors and patients should be cautious in utilizing grapefruit effect," said Bailey.

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TRY 10 ENGINEERING STRESS RELIEVERS FROM VARIOUS COUNTRIES

Whatever civilization and the condition of a nation, all of them must have experienced stress, although the term may vary. Stress is a condition in which the body's mental and physical pressure. And prolonged stress is not managed properly can lead to depression.

There is a proverb that reads Other Other Field Grasshopper, Other Other Lubuk The fish. That is, each region has a different way to handle the problem. The way it is generally based on tradition and local culture, but later became a habit that conserved.

As reported by Health.com, on Monday (26/11/2012), here are the ways of the various countries of the world to relieve stress.

1. Petit Aperitif in France

After the move and under stress, the French used to relax by doing petit aperitif, which is a small ritual by drinking a glass of wine accompanied by cashew nuts or chips, hummus and olive oil. The next thing to do is cook dinner.

Grape known in Europe has a relaxing effect. But more important is the ritual to separate the chaos at work from the comfort of home. Every ritual is carried comfortably can eliminate stress, both light exercise and talking with friends.

2. Sauna bath in Russia

To relieve the stress, the Russians are often gripped by the cold will do the sauna or steam bath using hot water. Just sitting in the extreme heat with sweat washing the body is able to be healers soul.

Warm bath or a hot steam bath not only create a warm hug skin, but a study from Yale University suggests that the warmth of the hot water vapor can trigger the brain and the body's response to emotional warmth and improves mood. Limit the sauna for 10 minutes to avoid dry skin.

3. Been to Home Friends Ala Denmark

Danish people to relax in understated enough friends or relatives house at night and weekends. The important thing is being happy at home and did not rush to go anywhere.

Create a party, the key is also simple, do not bother. If worried invite others to a party that had a perfect holiday, then the stress will also appear. Then weekends only meeting simple, usually enough desserts and beverages served.

4. Massage in Thailand

Thailand seems to have a similar tradition with Indonesia to relieve stress, ie massage. Massages are performed also similar, which is done with a strong, plus the pressure through the knee and elbow to eliminate stress.

Massaging the base of the neck and the surrounding area will release the hormone serotonin, a natural antidepressant. This effect will be even more powerful if asked couples doing the massage.

5. Drinking Mate in Argentina

In Argentina, there is a drink called mate, which circulated hot herbal drinks with friends like peace pipe on the Indians. It made the people so connected with the group and lowers stress.

According to a study in Belgium, eat or drink with a soothing release the hormone oxytocin. The existence of strong ties with the group would make someone be appreciated by others in the vicinity.

6. Laughter exercises in India

Every morning, several people in India do exercises laughing with smiling, waving and jumping. The more often this exercise is done, the better the resulting mood.

When laughing, the abdominal muscles to contract and trigger endorphins that make you feel better feelings, according to research from the University of Oxford. Laughed for a few minutes alone can soothe. Therefore, it is better to record a show or event humor favorites to watch again the night after the move.

7. Walk in Ireland

In cold weather though, in Ireland will remain often found people walking around outside with the kids. This method can be trusted to 'turn on' the brain back and give energy.

A study in 2012 found that people who rode a stationary bike for 30 minutes and then look at the photos turned out to be less anxiety disturbing than people who just sit quietly. It turns out exercise not only reduces anxiety, but also helped create a feeling of calm when faced with distressing events.

8. Together coffee in Sweden

In Sweden, there is a term called fika, the rest with a cup of coffee with friends. This little ritual has become part of the culture there since the 1700s. In many companies, employees do fika at about 10 am and 3 pm to go to a cafe drinking latte, tea or smoothie accompanied cinnamon, muffins, or macaroni.

Fika create a comfortable and peaceful feeling. A study conducted Massachusetts Institute of Technology found that people who socialize towards the end of the work day will be more productive than the 10-15% that do not socialize.

9. Foot soak in China

Chinese people used to soak feet in a large pot of hot water or referred to as 'yu zu' before bed. Usually done while sitting on the couch while reading a book or surfing the internet to fall asleep.

Ankle foot soak up the hot water is added salt and 2 tablespoons baking soda for 15 minutes can reduce swelling and improve blood circulation. In addition, the effect can also be soothing.

10. Keyif in Turkey

Turkish people used to do Keyif, it means enjoying pleasant things. Can practice by listening to music or straighten the legs and not think about anything that causes stress.

Stressful thoughts often come from the assumption that something bad will happen. If you can focus on the positive, negative thoughts trigger stress will disappear or at least diminish. One study found that people who were given a cold compress will greatly diminished sense of comfort when disambi not listen to music.

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TOO LITTLE OR EQUALLY MOST DANGEROUS SPORTS FOR KNEE

Lack of physical activity in middle age may cause the deterioration of cartilage in the knee and the risk of knee osteoarthritis. But based on research, too much physical activity in this age also have the same risks.

A new study says that high levels of physical activity and low, they may accelerate cartilage damage to the knee in adults who have middle-aged.

Researchers at the University of California San Francisco (UCSF) have previously found an association between physical activity with cartilage degeneration. However, the study only focused on one point of time.

UCSF researchers see changes in knee cartilage in a group of middle-aged adults during the 4-year study period. Researchers used magnetic resonance imaging (MRI)-based T2 relaxation time (part-time) to track the evolution of early degenerative changes in the knee cartilage.

"T2 relaxation time produced by MRI allows for the analysis of biochemical and molecular composition of cartilage. An increase in water mobility in damaged cartilage, and the resulting increase in water mobility increased T2 relaxation time, "Wilson said Lin, who led the study.

Researchers analyzed 205 patients aged 45 to 60 years, from UCSF Osteoarthritis Initiative, a national study funded by the National Institutes of Health for the prevention and treatment of knee osteoarthritis.
Participants were asked to fill out questionnaires to record their physical activity then researchers measured T2 values ​​of cartilage in the femur, tibia and patella of the right knee joint at baseline, 2-year and 4-year study at the end of the study.

According to the study, people who often participate in sports such as running with high intensity, have been associated with a more degenerate cartilage and increased risk for development of osteoarthritis.

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7 SIGNS YOUR OBSESSION ON SPORTS CAN BE DANGEROUS BODY

Maintain health and fitness to sports or physical exercise is very important. But if exercise is done too much to memforsir power, which happens not to be healthy but health problems. These are the signs you exercise excessively and should be immediately wary, quoted from Time Gal.

1. Not Compromise on Health

There are times when the schedule is very solid routines so hours of sleep is reduced and the body was not fit. If you are experiencing now feel guilty for not being able to exercise, it is a problem that must be avoided. When you are injured, have a fever or lack of sleep but still think going to the gym is very important, it has become a problem that must be addressed. Regular exercise is necessary, but not what the occasional sports schedules passed.

2. Exercise is a Liability

Although the workout at the gym can make you feel happy, but it should not be a liability. Do exercise at intervals should be, because if it is too demanding it every day then it is not fun anymore training activities.

3. Calorie is the Enemy

If every time you eat foods calculate how long it takes to burn calories back, then maybe you are obsessed. Avoid the need not worry too much about calories into the body because the body also needs calories for energy.

4. Down Drastic Weight Loss

Someone who are obese tend to lose weight drastically when beginning a diet and exercise. In fact, the weight loss of more than 1.3 kg per week then it means you push yourself too hard.

5. Not Balanced

Do not get a solid workout schedule snatch happiness because it must pass through a preferred activity. Take the time to socialize with friends or family because it is not as important as exercise.

6. Prone to Injury

People who are prone to diligent exercise because muscle injury that kept working. If the center was injured, do not force yourself to exercise regularly but istirahatkanlah yourself so that you can recover health.

7. Run out of steam

Sports provide power is indeed a fact. However, if excessive exercise will harm you.

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WHAT IS THE RECOVERY BOILER?

Definition Recovery Boiler

Recovery Boiler A boiler is a special unit used to purify the compound - an organic chemical compounds contained in Black Liquor (waste cooking from the digester) and at the same time as high-pressure steam generator (High Pressure Steam).

Heavy Black Liquor (70% solid) containing:

An organic compound with the main content of Na2CO3, Na2SO4, NaOH, Na2S.
Organic compounds derived from wood during cooking in the digester in the form of wood fibers, ligmin
Water
Heat energy contained in the Heavy Black Liquor range 3100 - 3500 kcal / kg dry solid.
Heat energy is partly used to convert the organic compounds and partly used as fuel to generate steam
Heavy Black Liquor Evaporator Vacuum produced by the input to the Mixing Tank, in the mixing tank mixed with combustion ash from ESP (Electrostatic precipitator) and-1 from the economizer, economizer-2, Boiler Bank, then added with salt cake (Na2SO4 powder).
Once mixed in the Mixing Tank, Heavy Black Liquor (HBL) is sprayed into the furnace to burn through the spray gun. Prior to the furnace going process of drying by blowing hot air, then collects in the bottom of the furnace to form charbed and caught fire after reaching the point of combustion.
Combustion air needs exhaled through the Primary, Secondary and Tertiary wind boxes located around the bottom of the furnace wall.

To start combustion in the furnace as well as to stabilize the combustion conditions, use of diesel fuel is sprayed through a burner into the furnace.
During combustion, the following process takes place in the furnace are:
1. The compound - organic compound burning releases heat and partly turned into a gas.
2. Sodium sulphate (Na2SO4) contained in the HBL and the salt cake is reduced to a compound of sodium sulphite (Na2S)
Na2SO4 + 2C + 2 Co2 Ns2S
The speed reduction is calculated:
Reduction Rate: Na2S. X 100%
Na2S + Na2SO4
3. The compound - an organic compound called Smelt melt like lava.
If the conditions of combustion is complete, reduction rate reached> 95%
A melt of organic chemicals (smelt) will accumulate around the side charbed smelt spout and flow out into the dissolving tank, where in the dissolving tank, smelt will be dissolved with WLL (WEAK White Liquor) from RC, the mixture of smelt with the WLL-called Green liquor (GL) which is pumped from the dissolving tank RB to RC section for the Recausticyzing be WL (White Liquor) or cooking liquor
For reuse as raw wood cooking in digester (Pulp Making Section)

Time of air and gases - gases of combustion, called flue gas still contains a high amount of heat Energy.
Flue gas is inhaled / drawn by a device called the Induced Draft Fan (IDF), where the flue gas will pass through the pipe - boiler pipe so that water contained in boiler piping briefly - of land become heated and turned into high-pressure steam will then be used for the propulsion of Turbine Generator to generate electrical energy.
So the production side of the Recovery Boiler is STEAM high pressure (60 bar)

Smelt Reduction Efficiency:
Na2SO4 + 2C + Heat ----- Na2S + 2CO2
SRE = Na2S/Na2S + Na2SO4 x 100%
Recauticizing
--- CaO + H2O Ca (OH) 2
Ca (OH) 2 + Na2CO3 --- 2NaOH + CaCO3
CaCO3 + Heat ----- CaO + CO2

History of Recovery Boiler

Kraft Porridge was first developed in Germany in 1870's, in a strong sense in Germany: kraft pulp fiber slurry to produce hard at a short maturation process.
Addition of Na2SO4 will be accelerated with delignification process without reducing the strength of pulp fibers.
Pulp first made in 1909 in the city Roanake Rapids, North Carolina, kraft pulp growing popularity, in 1930 to found the Recovery Boiler is made more economical kraft pulp.
Today kraft pulp about 70% is produced in America.

Feed Water to Steam Cycle Recovery Boiler 6
Demineralizer water (steam PG) Feed Water Tanks economizer economizer 1 2 Dolezal (to RB & RB-6-12) Steam drum bottom of steam drum to the boiler wall piping, furnaces & Steam Boiler drum bank top to the screen tube Primary Secondary superheater superheater Tertiary superheater steam to the turbine generator.

Park Pressure Recovery Boiler
1. Furnace site of a combustion process HBL
2. Superheater is placed over the furnace, and the screen is protected with a nose tube.

Nose is designed to produce flue gas flow pressure of a strong and directed to the superheater, as well as to protect the superheater from the excess. Then superheater which comes from the furnace to the superheater. This event continues from primary superheater, secondary and tertiary superheater superheater.
3. Screen Tube
To avoid direct heat flue gas coming from the furnace to the superheater and the lower the temperature of the furnace by means used by the screen tube.
4. Boiler Bank
Its location is situated behind the superheater.
5. Economizer
Economizer economizer consists of 1 & 2 is the long stream counter flow between the flow of flue gas and feed water

Factors Supporting Recovery Boiler

1. Soot Blowing System
Aims to bring down the soot blowers or clean ash piping attached to the inside of the boiler (superheater, boiler bank, economizer).
RB-6, has 86 sets Sootblower (43 to the left, 43 top right)
2. Medium Pressure Steam
For Air preheater, start-up burner, smelt spout steam shuttering.
3. Low Pressure Steam
For water preheater
4. Condensate
5. Electrostatic precipitator (ESP)
Each RB must be equipped with ESP which is useful for capturing particles - solid particles contained in the flue gas further solid particles (ash) is returned to the mixing tank to be mixed with HBL
RB-5 Equipped with 2 sets ESP
RB-6 & 12 are equipped with 3 sets ESP
RB-11 is equipped with 4 sets ESP

Recovery Boiler is also equipped with security system

1. Interlock System
This system serves to prevent damage in case of irregularities Boiler operating conditions.
2. Safety Valve
This tool serves to keep the boiler pressure does not exceed the limits specified security pressures.
3. Rappid Drain System.
This system serves to empty the water boiler to a minimum label, if there is a severe leakage in the piping boiler causing water to enter into the furnace.
This system operated at the time of emergency and went so fast for Boilers avoid further damage.

RB Quality Control

1. Demineralizer Water Conductivity pH 6.0 ~ 8.0 <5.0 ms / cm 2. Feed Water Conductivity pH 8.0 ~ 9.5 <5.0 ms / cm SiO2 <40.0 ~ 50.0 ppb 10.0 ppb N2H4 3. Boiler water pH 9.5 ~ 10.5 Conductivity <150.0 mx / cm PO4 2.0 ~ 12.0 ppm SiO2 <3:50 ppm 4. Saturated Steam Conductivity pH 7.5 ~ 9.5 <5.0 ms / cm SiO2 <40.0 ppb 5. Steam superheater Conductivity pH 7.5 ~ 9.5 <5.0 mx / cm SiO2 <40.0 ppb 6. Green Liquor NaOH 12.0 ~ 20.0 g / l Na2S 25.0 ~ 35.0 g / l Na2CO3 70.0 ~ 85.0 g / l TSS <1500 ppm 7. Smelt Reduction rate> 95.0%.see also previous article"How does a power plant boiler work?".

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HOW DOES A POWER PLANT BOILER WORK

This time articel is i will study about how recovery boiler work. after yesterday I was talking about "THE ELECTROSTATIC PRECIPITATOR".The boiler generates high pressure steam by transfering the heat of Combustion in various heat transfer sections. This part of the article series briefly describes the flow and arrangement of the heat transfer sections in a boiler. In line diagrams help make the concept clear. The Basics. Volume of one unit mass of steam is thousand times that of water, When water is converted to steam in a closed vessel the pressure will increase. Boiler uses this principle to produce high pressure steam. Conversion of Water to Steam evolves in three stages. • Heating the water from cold condition to boiling point or saturation temperature – sensible heat addition. • Water boils at saturation temperature to produce steam - Latent heat.addition. • Heating steam from saturation temperature to higher temperature called Superheating to increase the power plant output and efficiency. Sensible Heat Addition Feed Water Pump. The first step is to get a constant supply of water at high pressure into the boiler. Since the boiler is always at a high pressure. ‘Boiler feed water pump’ pumps the water at high pressure into the boiler from the ‘feed water tank’. The pump is akin to the heart in the human body. Pre-Heating 'Feed water heaters’, using extracted steam from the turbine, adds a part of the sensible heat even before the water enters the boiler. Economiser. Most of the sensible heat is absorbed in the Economiser. These are a set of coils made from steel tubes located in the tail end of a boiler. The hot gases leaving the boiler furnace heat the water in the coils. The water temperature is slightly less than the saturation temperature. From the economiser the water is fed to the 'drum'. Pre-Heating & Economiser Latent Heat Addition Drum. The drum itself a large cylindrical vessel that functions as the storage and feeding point for water and the collection point for water and steam mixture. This is the largest and most important pressure part in the boiler and weighs in the range 250 Tons for 600 MW power plant. Water Walls Boiling takes place in the ‘Water Walls’ which are water filled tubes that form the walls of the furnace. Water Walls get the water from the ‘downcomers’ which are large pipes connected to the drum. The downcomers and the water wall tubes form the two legs of a water column. As the water heats up in the furnace a part of the water in the water-wall tubes becomes steam. This water steam mixture has a lower density than the water in the downcomers. This density difference creates a circulation of water from the drum, through the downcomers, water walls and back to the drum. Steam collects at the upper half of the drum. The steam is then sent to the next sections. The temperature in the drum, downcomers and water wall is at the saturation temperature. WaterWalls SuperHeat / ReHeat SuperHeater Steam from the drum passes to the SuperHeater coils placed in the Flue gas path.. The steam temperature increases from the saturation temperature till the maximum required for operation. The superheated steam then finally goes to the turbine.Final Superheater temperatures are in the Range of 540 to 570 °C for large power plants and SuperHeated steam pressures are around 175 bar. Reheater Steam from the exhaust of the first stage turbine goes back to the boiler for reheating and is returned to the second stage. Reheater coils in the flue gas path does the reheating of the returned steam. The reheat steam is at a much lower pressure than the super heated steam but the final reheater temperature is the same as the superheated steam temperature. Reheating to high temperatures improves the output and efficiency of the Power Plant. Final Reheater temperatures are normally in the range of 560 to 600 °C. Reheat steam pressures are normally around 45 bar. SuperHeater / ReHeater The above are the major water and steam circuit items in a boiler and are collectively called the ‘pressure parts’.
see also previous article "What is the electrostatic precipitator ?"
Maybe Useful.

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MECHANISMS OF STEAM SOOT BLOWER EROSION

There are many mechanisms that can cause steam soot blower erosion of boiler tubes at various heat transfer sections. Knowing the way these mechanisms contribute to erosion will help to prevent loss of availability of boiler.

Soot blowers are provided in boilers at various locations like water-walls, superheaters, reheaters, economizers and air pre-heaters. Steam soot blowers have specific advantage and disadvantages over other types. The advantages being mainly their low capital cost, operating cost and the effectiveness of cleaning in areas like furnace, superheaters and reheaters.

The major disadvantages are they need a higher level of maintenance; effectiveness is low in oil firing mainly in air pre-heater area. They need warm up and condensate draining before startup. The mechanisms of steam soot blower erosion of heat transfer tubes can be a single factor or multiple factors acting individually or in unison. There are much more than hundred soot boilers in boilers generating and supplying steam for a 500 MW and above plants.

Possible mechanisms

• All blowers are set to be set at the right steam pressure recommended by the designer if this is not done then it leads to poor cleaning or higher rate of tube erosion due to high steam pressure. This is true for all soot blowers in the boiler starting from furnace to air pre-heater.
• The alignment of the blower with respect to the furnace walls, superheater tubes, reheater tubes, economizer tubes and air pre-heater tubes or elements is very critical and not maintaining this leads to erosion of the tubes and subsequent metal wastage. The thinning of the tubes finally leads to pinhole failures and many secondary figures due to this depending upon the orientation of the leak.
• It is required to ensure at least 50 degree centigrade of super heat in the steam being used for blowing. If the super heat in the steam is lower than required then during blowing wet steam impinge the tubes at high velocity and the impact force damaging the heat transfer tubes. This can be identified by the typical spit like metal wastage on the tubes surrounding the blower’s area of effectiveness.
• The duration of operation of blowers is another main reason for erosion of the heat transfer tubes. Even if you maintain the correct pressure and temperature the erosion will take place at a slow phase if duration is more than required.
• In coal fired boiler if alignment is not correct then the ash deposits being cleaned can get entrained and cause erosion of tubes. However in oil fired boilers it is not a mechanism that can happen due to the fact that the ash in oil is not significant at all.
• The higher frequency of operation of the soot blowers than needed also leads to tube erosion.
• Optimizing the soot blower operation is important as operating those blowers where deposits are not there or very low will lead to metal wastage over a period of time.
• Failure to drain the condensate in the soot blower steam pipes is also contributing mechanism of tube erosion. The condensate gets entrained in the steam while the blower operates and has a much higher damaging effect than the lower degree of superheat in steam.

It has been seen in many boilers, mainly coal fired boilers, the soot blower erosion is one of the main contributing factors for loss of boiler availability. In the case of chemical recovery boilers also the soot blowers attribute to the loss of availability of boiler in a significant way

Soot blowers keep the heat transfer surfaces in a boiler clean. A brief description of the working of soot blowers is given in this article.

Chimney Sweeps have been legendary characters in English literature from Hans Christian Anderson to Charles Dickens. In the earlier days when houses had fireplaces, the Chimney Sweep did the function of cleaning the soot from the chimney. In the modern day boiler, the soot blower does the same function.

In oil fired boilers, over a period of time the heat transfer tubes get covered by a layer of soot or fine carbon deposit. This reduces the heat transfer from the hot gases to the water and reduces the efficiency of the boiler.

In coal fired boilers, the furnace area gets covered by slag which is molten ash. The ash also sticks to the heat transfer surface in the other heat transfer areas. These ash accumulations reduce heat transfer and increase the tube metal temperatures leading to failure of the tubes.

.

Tube cleaning is done periodically to remove the ash or soot deposits. Steam is the medium used for cleaning. The steam is taken from the boiler itself.

The soot blower consists of a lance tube with a nozzle at the end. When it is operated, the lance is extended into the boiler and steam is admitted through the lance. The steam comes out as a high velocity jet through the nozzles, which cleans the ash deposited on the surface. When the lance moves into the boiler it is also rotating so that it cleans the sweeping area covered by the circular travel of the nozzle. The lance is then retracted back.

There are two types of soot blowers.

• One with a very long lance called the “long retractable soot blowers.” This is normally used to clean the ash deposit from between the coils of superheaters and economisers.

• The other type is the shorter lance type called the “wall blowers.” These are used to clean the furnace walls. The lance extends a short distance around 200 mm from the furnace wall. The nozzle direction is such that the steam impinges on the walls cleaning the surface. During operation, the lance rotates cleaning the radial area covered by the steam from the nozzle.

The deposits on the walls are due to the chemical constituents of ash, and the amount of combustion air. If the ash contains more of Ferrous Sulphide, then the melting temperature of the ash is low which makes the ash melt and stick to the walls.

A large coal fired Thermal power plant will have around two hundred soot blowers of both types arranged to cover all the area of the boiler. This will be programmed to automatically operate to a required sequence.

Intelligent soot blower systems calculate the trends in the temperature increase in different sections of a boiler. The program then decides which soot blowers have to be operated and at what frequency.

High-pressure water lances are also used in some units where the slagging is very heavy.
see also previous article "What is the black liquor?"

May be useful.

.

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FURNACE CAMERA

This day i will taking about Furnace Camera.As the current technological developments in power plant technology especially the use of recovery boiler is constantly innovating in order to complement the existing deficiencies in the means of production to facilitate the operation of the recovery boiler.

Currently the power plant that uses a recovery boiler there is a lack of technology to the unavailability of a device to control the conditions inside the boiler (furnace). So far the recovery boiler operator can only monitor the condition of the inside of the furnace manually just by looking at the field by controlling the air of room pannel (dcs). but that's not enough data taken with the actual data. accuracy conditions may only be 65% to monitor conditions inside the furnace charbed.

               

Camera Enclosure with Lens

The above shows what is removed and store during shutdown or repair

Camera Enclosure Interior

Back of camera core

Removing Camera Core

Camera Retract system

Camera Port

Cleaner

Control Enclosure

Solenoid valve assembly

(Inside control enclosure)

Valve Manual override

Siemens LOGO PLC

Settable Parameter available from key pad on Logo:

Cycle time (time between cleaning cycles)

Cleaning stroke time (time energized and de-energized

Number of cleaning strokes

 

Pneumatic System

Lens tube/manifold pressure to be maintained between 1.5 and 2 BAR

Input pressure to the system should be 5 and 12 bar

The cleaning cylinder (with check valve) acts as an accumulator to retract camera in the event of a line failure.

System Faults and General Maintenance

LENS CLEANING

The most common form of maintenance on the camera lens system will be cleaning the “objective” lens – that part of the lens system furthest from the camera. Periodic, daily cleaning of the objective lens should be expected, although cleaning intervals of 5 or 6 days are not un-common.

A dirty objective will produce an image that is fuzzy or appears out of focus. The part of the objective that requires cleaning is the protective clear sapphire window, which is very hard and difficult to inadvertently scratch, but relatively easy to break.

Warning:

Do not attempt to clean a hot lens! The objective lens assembly must be below 110°F or comfortable to the touch before cleaning.

To clean the objective lens sapphire:

Retract the lens by selecting “RETRACT” at the control enclosure.

Allow the lens to cool for several minutes.

Once cool (relatively comfortable to the touch), turn the supply air to the lens system off at the shut-off valve.

Using a cotton swab and alcohol, reach into the end of the lens assembly and clean any dirt or oil that may have collected on the objective sapphire.

Char build-up on or around the lens tube should also be cleaned at this time.

Turn the supply air on.

Most Faults and the probable reason for the fault are broadcast on the face of the Control Panel

The camera has 30-seconds to cool down once an overtemp

Situation is discovered.

There are three different faults that will cause the camera to retract:

Camera enclosure over temp - temporary over temp recognized

Camera has retracted and then cooled to operating temp check air supply and for combustion air leaks

Camera over temp - system is shut down

Camera retracted and failed to cool within 30 seconds camera has been shut off as result to avoid damage. Check air supply and cooler adjustment.

Low air pressure – camera retracted to avoid overheating

Check for compressed air leaks and ball valve position

Retract limit fail – automatic cleaning not possible

Important to keep the retract cleaned and lubricated so if a overtemp condition occurs the retract can do what it is supposed to do

Output fail check fuse 1

Output fail check fuse 2

Output fail check fuse 3

There are three different ouput faults that are monitored

Maybe usefull.

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WHAT IS THE BLACK LIQUOR?

Concentrated black liquor contains organic dissolved wood residue in addition to sodium sulfate from the cooking chemicals added at the digester. Combustion of the organic portion of chemicals produces heat. In the recovery boiler heat is used to produce high pressure steam, which is used to generate electricity in a turbine. The turbine exhaust, low pressure steam is used for process heating.


Combustion of black liquor in the recovery boiler furnace needs to be controlled carefully. High concentration of sulfur requires optimum process conditions to avoid production of sulfur dioxide and reduced sulfur gas emissions. In addition to environmentally clean combustion, reduction of inorganic sulfur must be achieved in the char bed.


The recovery boiler process has several unit processes:



Combustion of organic material in black liquor to generate steam
Reduction of inorganic sulfur compounds to sodium sulfide, which exits at the bottom as smelt
Production of molten inorganic flow of mainly sodium carbonate and sodium sulfide, which is later recycled to the digester after being re-dissolved
Recovery of inorganic dust from flue gas to save chemicals
Production of sodium fume to capture combustion residue of released sulfur compounds

First recovery boilers


Some features of the original recovery boiler have remained unchanged to this day. It was the first recovery equipment type where all processes occurred in a single vessel. The drying, combustion and subsequent reactions of black liquor all occur inside a cooled furnace. This is the main idea in Tomlinson’s work.


Secondly the combustion is aided by spraying the black liquor into small droplets. Controlling process by directing spray proved easy. Spraying was used in early rotary furnaces and with some success adapted to stationary furnace by H. K. Moore. Thirdly one can control the char bed by having primary air level at char bed surface and more levels above. Multiple level air system was introduced by C. L. Wagner.


Recovery boilers also improved the smelt removal. It is removed directly from the furnace through smelt spouts into a dissolving tank. Some of the first recovery units employed the use of Cottrell’s electrostatic precipitator for dust recovery.


Babcock & Wilcox was founded in 1867 and gained early fame with its water tube boilers. The company built and put into service the first black liquor recovery boiler in the world in 1929.This was soon followed by a unit with completely water cooled furnace at Windsor Mills in 1934. After reverberatory and rotating furnaces the recovery boiler was on its way.

The second early pioneer, Combustion Engineering based its recovery boiler design on the pioneering work of William M. Cary, who in 1926 designed three furnaces to operate with direct liquor spraying and on work by Adolph W. Waern and his recovery units.

Recovery boilers were soon licensed and produced in Scandinavia and Japan. These boilers were built by local manufacturers from drawings and with instructions of licensors. One of the early Scandinavian Tomlinson units employed a 8.0 m high furnace that had 2.8*4.1 m furnace bottom which expanded to 4.0*4.1 m at superheater entrance.

This unit stopped production for every weekend. In the beginning economizers had to be water washed twice every day, but after installation of shot sootblowing in the late 1940s the economizers could be cleaned at the regular weekend stop.

The construction utilized was very successful. One of the early Scandinavian boilers 160 t/day at Korsnäs, operated still almost 50 years later.

Development of recovery boiler technology

The use of Kraft recovery boilers spread fast as functioning chemical recovery gave Kraft pulping an economic edge over sulfite pulping.

The first recovery boilers had horizontal evaporator surfaces, followed by superheaters and more evaporation surfaces. These boilers resembled the state-of-the-art boilers of some 30 years earlier. This trend has continued until today. Since a halt in the production line will cost a lot of money the adopted technology in recovery boilers tends to be conservative.

The first recovery boilers had severe problems with fouling.

Tube spacing wide enough for normal operation of a coal fired boiler had to be wider for recovery boilers. This gave satisfactory performance of about a week before a water wash. Mechanical sootblowers were also quickly adopted. To control chemical losses and lower the cost of purchased chemicals electrostatic precipitators were added. Lowering dust losses in flue gaseshas more than 60 years of practice.


One should also note square headers in the 1940 recovery boiler. The air levels in recovery boilers soon standardized to two: a primary air level at the char bed level and a secondary above the liquor guns.

In the first tens of years the furnace lining was of refractory brick. The flow of smelt on the walls causes extensive replacement and soon designs that eliminated the use of bricks were developed.

Improving air systems

To achieve solid operation and low emissions the recovery boiler air system needs to be properly designed. Air system development continues and has been continuing as long as recovery boilers have existed.As soon as the target set for the air system has been met new targets are given. Currently the new air systems have achieved low NOx, but are still working on lowering fouling. Table 1 visualizes the development of air systems.

Table 1: Development of air systems.

Air system

Main target

But also should


1st generation

Stable burning of black liquor


2nd generation

high reduction

Burn liquor


3rd generation

decrease sulfur emissions

Burn black liquor, high reduction


4th generation

low NOx

Burn black liquor, high reduction and low sulfur emission


5th generation

decrease superheater and boiler bank fouling

Burn black liquor, high reduction, low emissions



The first generation air system in the 1940s and 1950s consisted of a two level arrangement; primary air for maintaining the reduction zone and secondary air below the liquor guns for final oxidation.The recovery boiler size was 100 – 300 TDS (tons of dry solids) per day. and black liquor concentration 45 – 55 %. Frequently to sustain combustion auxiliary fuel needed to be fired. Primary air was 60 – 70 % of total air with secondary the rest. In all levels openings were small and design velocities were 40 – 45 m/s. Both air levels were operated at 150oC. Liquor gun or guns were oscillating. Main problems were high carryover, plugging and low reduction. But the function, combustion of black liquor, could be filled.

The second generation air system targeted high reduction. In 1954 CE moved their secondary air from about 1 m below the liquor guns to about 2 m above them.The air ratios and temperatures remained the same, but to increase mixing 50 m/s secondary air velocities were used. CE changed their frontwall/backwall secondary to tangential firing at that time. In tangential air system the air nozzles are in the furnace corners. The preferred method is to create a swirl of almost the total furnace width. In large units the swirl caused left and right imbalances. This kind of air system with increased dry solids managed to increase lower furnace temperatures and achieve reasonable reduction. B&W had already adopted the three-level air feeding by then.

Third generation air system was the three level air. In Europe the use of three levels of air feeding with primary and secondary below the liquor guns started about 1980. At the same time stationary firing gained ground. Use of about 50 % secondary seemed to give hot and stable lower furnace.Higher black liquor solids 65 – 70 % started to be in use. Hotter lower furnace and improved reduction were reported. With three level air and higher dry solids the sulfur emissions could be kept in place.

Fourth generation air systems are the multilevel air and the vertical air. As the feed of black liquor dry solids to the recovery boiler have increased, achieving low sulfur emissions is not anymore the target of the air system. Instead low NOx and low carryover are the new targets.
Multilevel air

The three-level air system was a significant improvement, but better results were required. Use of CFD models offered a new insight of air system workings. The first to develop a new air system was Kvaerner (Tampella) with their 1990 multilevel secondary air in Kemi, Finland, which was later adapted to a string of large recovery boilers.Kvaerner also patented the four level air system, where additional air level is added above the tertiary air level. This enables significant NOx reduction.
Vertical air

Vertical air mixing was invented by Erik Uppstu.His idea is to turn traditional vertical mixing to horizontal mixing. Closely spaced jets will form a flat plane. In traditional boilers this plane has been formed by secondary air. By placing the planes to 2/3 or 3/4 arrangement improved mixing results. Vertical air has a potential to reduce NOx as staging air helps in decreasing emissions.In vertical air mixing, primary air supply is arranged conventionally. Rest of the air ports are placed on interlacing 2/3 or 3/4 arrangement.

Black liquor dry solids






Net heating values of industrial black liquors at various concentrations

As fired black liquor is a mixture of organics, inorganics and water. Typically the amount of water is expressed as mass ratio of dried black liquor to unit of black liquor before drying. This ratio is called the black liquor dry solids.

If the black liquor dry solids is below 20 % or water content in black liquor is above 80 % the net heating value of black liquor is negative. This means that all heat from combustion of organics in black liquor is spent evaporating the water it contains. The higher the dry solids, the less water the black liquor contains and the hotter the adiabatic combustion temperature.

Black liquor dry solids have always been limited by the ability of available evaporation.Virgin black liquor dry solids of recovery boilers is shown as a function of purchase year of that boiler.







Virgin black liquor dry solids as a function of purchase year of the recovery boiler

When looking at the virgin black liquor dry solids we note that on average dry solids has increased. This is especially true for latest very large recovery boilers. Design dry solids for green field mills have been either 80 or 85 % dry solids. 80 % (or before that 75 %) dry solids has been in use in Asia and South America. 85 % (or before that 80 %) has been in use in Scandinavia and Europe.
High temperature and pressure recovery boiler

Development of recovery boiler main steam pressure and temperature was rapid at the beginning. By 1955, not even 20 years from birth of recovery boiler highest steam pressures were 10.0 MPa and 480oC. The pressures and temperatures used then backed downward somewhat due to safety.By 1980 there were about 700 recovery boilers in the world.





Development of recovery boiler pressure, temperature and capacity.
Safety


One of the main hazards in operation of recovery boilers is the smelt-water explosion. This can happen if even a small amount of water is mixed with the solids in high temperature. Smelt-water explosion is purely a physical phenomenon. The smelt water explosion phenomena have been studied by Grace.By 1980 there were about 700 recovery boilers in the world.The liquid - liquid type explosion mechanism has been established as one of the main causes of recovery boiler explosions.

In the smelt water explosion even a few liters of water, when mixed with molten smelt can violently turn to steam in few tenths of a second. Char bed and water can coexist as steam blanketing reduces heat transfer. Some trigger event destroys the balance and water is evaporated quickly through direct contact with smelt. This sudden evaporation causes increase of volume and a pressure wave of some 10 000 – 100 000 Pa. The force is usually sufficient to cause all furnace walls to bend out of shape. Safety of equipment and personnel requires an immediate shutdown of the recovery boiler if there is a possibility that water has entered the furnace. All recovery boilers have to be equipped with special automatic shutdown sequence.

The other type of explosions is the combustible gases explosion. For this to happen the fuel and the air have to be mixed before the ignition. Typical conditions are either a blackout (loss of flame) without purge of furnace or continuous operation in a substoichiometric state. To detect blackout flame monitoring devices are installed, with subsequent interlocked purge and startup. Combustible gas explosions are connected with oil/gas firing in the boiler. As also continuous O2 monitoring is practiced in virtually every boiler the noncombustible gas explosions have become very rare.
Modern recovery boiler

The modern recovery boiler is of a single drum design, with vertical steam generating bank and wide spaced superheaters. This design was first proposed by Colin MacCallum in 1973 in a proposal by Götaverken (now Metso Power inc.) for a large recovery boiler having a capacity of 4,000,000 lb of black liquor solids per day for a boiler in Skutskär, Sweden, but this design was rejected as being too advanced at that time by the prospective owner. MacCallum presented the design at BLRBAC and in a paper "The Radiant Recovery Boiler" printed in Tappi magazine in December 1980. The first boiler of this single-drum design was sold by Götaverken at Leaf River in Mississippi in 1984. The construction of the vertical steam generating bank is similar to the vertical economizer. Vertical boiler bank is easy to keep clean. The spacing between superheater panels increased and leveled off at over 300 but under 400 mm. Wide spacing in superheaters helps to minimize fouling. This arrangement, in combination with sweetwater attemperators, ensures maximum protection against corrosion. There have been numerous improvements in recovery boiler materials to limit corrosion.
The effect of increasing dry solids concentration has had a significant effect on the main operating variables. The steam flow increases with increasing black liquor dry solids content. Increasing closure of the pulp mill means that less heat per unit of black liquor dry solids will be available in the furnace. The flue gas heat loss will decrease as the flue gas flow diminishes. Increasing black liquor dry solids is especially helpful since the recovery boiler capacity is often limited by the flue gas flow.





A modern recovery boiler consists of heat transfer surfaces made of steel tube; furnace-1, superheaters-2, boiler generating bank-3 and economizers-4. The steam drum-5 design is of single-drum type. The air and black liquor are introduced through primary and secondary air ports-6, liquor guns-7 and tertiary air ports-8. The combustion residue, smelt exits through smelt spouts-9 to the dissolving tank-10.

The nominal furnace loading has increased during the last ten years and will continue to increase. Changes in air design have increased furnace temperatures.This has enabled a significant increase in hearth solids loading (HSL) with only a modest design increase in hearth heat release rate (HHRR). The average flue gas flow decreases as less water vapor is present. So the vertical flue gas velocities can be reduced even with increasing temperatures in lower furnace.

The most marked change has been the adoption of single drum construction. This change has been partly affected by the more reliable water quality control. The advantages of a single drum boiler compared to a bi drum are the improved safety and availability. Single drum boilers can be built to higher pressures and bigger capacities. Savings can be achieved with decreased erection time. There is less tube joints in the single drum construction so drums with improved startup curves can be built.

The construction of the vertical steam generating bank is similar to the vertical economizer, which based on experience is very easy to keep clean.Vertical flue gas flow path improves the cleanability with high dust loading.To minimize the risk for plugging and maximize the efficiency of cleaning both the generating bank and the economizers are arranged on generous side spacing. Plugging of a two drum boiler bank is often caused by the tight spacing between the tubes.

The spacing between superheater panels has increased. All superheaters are now wide spaced to minimize fouling. This arrangement, in combination with sweetwater attemperators, ensures maximum protection against corrosion. With wide spacing plugging of the superheaters becomes less likely, the deposit cleaning is easier and the sootblowing steam consumption is lower. Increased number of superheaters facilitates the control of superheater outlet steam temperature especially during start ups.

The lower loops of hottest superheaters can be made of austenitic material, with better corrosion resistance. The steam velocity in the hottest superheater tubes is high, decreasing the tube surface temperature. Low tube surface temperatures are essential to prevent superheater corrosion. A high steam side pressure loss over the hot superheaters ensures uniform steam flow in tube elements.
Future prospects
Recovery boilers have been the preferred mode of Kraft mill chemical recovery since the 1930s and the process has been improved considerably since the first generation. There have been attempts to replace the Tomlinson recovery boiler with recovery systems yielding higher efficiency. The most promising candidate appears to be gasification,where Chemrec's technology for entrained flow gasification of black liquor could prove to be a strong contender.

Even if new technology is able to compete with traditional recovery boiler technology the transition will most likely be gradual. First, manufacturers of recovery boilers such as Metso, Andritz andMitsubishi, can be expected to continue development of their products. Second, Tomlinson recovery boilers have a long life span, often around 40 years, and will probably not be replaced until the end of their economic lifetime, and may in the meantime be upgraded at intervals of 10 – 15 years.
see also previous article "Ncg (non condensible gases)"
May be useful.

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