It’s really amazing! You get paid to open & read the contents of RupeeMail. You receive promotional offers & special discounts in RupeeMail.

production of sugar

SUGARDESCRIPTION:

The sugar industry processes sugarcane and sugar beet to manufacture edible sugar more than 60% of the world’ssugar production is from sugar cane.

Sugar beet, sugar manufacturing is ahighly seasonal length of about 6 to 18 weeks for beets and 20 to 32 weeks forcane

Approximately 10% of the sugar canecan be processed to commercial sugar, using approximately 20 cubic meters ofwater per metric ton of cane processed. Sugar is also extracted from beet root

      Sugar cane contains:

§  70% water

§  14%fiber

§  10 to 15% sucrose and

§  2.7% soluble impurities

RAWMATERIALS

1.                Sugar cane

2.                Sugar beats

Sugar is a board term applied to alarge number of carbohydrates present in many plants. In the sap of some plantsthe sugar mixtures are condensed into syrup.

 The feed accumulates sugar to about 15 percentof its weight. Sugar beet is a beetroot variety with the highest sugar content.About 3700000 tons of sugar is manufactured from sugar beet

STRUCTUREOF SUGARS:

Sucrose: a disaccharide of glucose(left) and fructose (right), important molecules in the body

Monosaccharide in a closed-chain formcan form glycosidic bonds with other monosaccharides, creating disaccharides(such as sucrose) and polysaccharides (such as starch). The prefix"glyco-" indicates the presence of a sugar in an otherwisenon-carbohydrate substance.

Monosaccharides include fructose,glucose, galactose and mannose. Disaccharides occur most commonly as sucrose(cane or beet sugar - made from one glucose and one fructose), lactose (milksugar - made from one glucose and one galactose) and maltose (made of twoglucoses). These disaccharides have the formula C₁₂H₂₂O₁₁.

Hydrolysis can convert sucrose into asyrup of fructose and glucose, producing invert sugar. This resultingsyrup, sweeter than the original sucrose, has uses in making confectionsbecause it does not crystallize as easily and thus produces a smoother finishedproduct.If combined with fine ash, sugar will burn with a blue flame

                           

The usualsugar cane constituents:

Constituents                                           %of total weight

H20                                                             69-75

Sucrose                                                       8-16

Reducing sugars                                           0.5-2

Organic substance                                        0.5-1

Nitrogenous bodies                                       0.5-1

Ash                                                             0.3-0.8

Fiber                                                            10-16

MANUFACTURINGPROCESS:

Planting and Harvesting:

Sugar cane requires an averagetemperature of 75 degrees Fahrenheit and uniform rainfall of about 80 inchesper year. Therefore, it is grown in tropical or subtropical areas.

Sugar cane takes about seven monthsto mature in a tropical and about 12-22 months in sub tropical area. At this time,fields of sugarcane are tested for sucrose and mature fields are harvested. Theharvesting is done primarily by machine.

Then the harvested cane stalks areloaded mechanically into trucks or railroads, cars and taken to mills forprocessing into raw sugars

PROCESSING:

Traditionally, sugarcane has beenprocessed in two stages. Sugarcane mills, located in sugarcane-producingregions, extract sugar from freshly harvested sugarcane, resulting in raw sugarfor later refining, and in "mill white" sugar for local consumption.Sugar refineries, often located in heavy sugar-consuming regions. Then thepurify raw sugar to produce refined white sugar, a product that is more than 99percent pure sucrose. These two stages are slowly becoming blurred. Increasingaffluence in the sugar-producing tropics has led to an increase in demand forrefined sugar products in those areas, where a trend toward combined millingand refining has developed.

Sugarcane first has to be moved to amill which is usually located close to the area of cultivation. Small railnetworks are a common method of transporting the cane to a mill. Once thefactories acquire the cane it will be subjected to the quality test. In Sri Lanka canewill be evaluated according to the brix and trash percentage.

JUICE EXTRACTION

In a sugar mill, sugarcane is washed,chopped, and shredded by revolving knives. The shredded cane is repeatedlymixed with water and crushed between rollers; the collected juices (calledgarapa in Brazil)contain 10–15 percent sucrose, and the remaining fibrous solids, calledbagasse, are burned for fuel. Bagasse makes a sugar mill more than self-sufficientin energy; the surplus bagasse can be used for animal feed, in papermanufacture, or burned to generate electricity for the local power grid.

Juice constituents:

Water                                       ---------->   75-85%

Sucrose                                    ---------->   10-21%

Other sugars                             ---------->    0.3-3%

Organic substance                     ---------->    0.2-0.6%

Nitrogenous bodies                   ---------->     0.5-1%

EVAPORATION

The cane juice is next mixed withlime to adjust its pH to 7. This mixing arrests sucrose's decay into glucoseand fructose, and precipitates out some impurities. The mixture then sits,allowing the lime and other suspended solids to settle out, and the clarifiedjuice is concentrated in a multiple-effect evaporator to make a syrup about 60percent by weight in sucrose. This syrup is further concentrated under vacuumuntil it becomes supersaturated, and then seeded with crystalline sugar. Uponcooling, sugar crystallizes out of the syrup.

CENTRIFUGE

A centrifuge is used to separate thesugar from the remaining liquid, or molasses. Additional crystallizations maybe performed to extract more sugar from the molasses; the molasses remainingafter no more sugar can be extracted from it in a cost-effective fashion iscalled blackstrap.

Raw sugar has a yellow to browncolour. If a white product is desired, sulfur dioxide may be bubbled throughthe cane juice before evaporation; this chemical bleaches many color-formingimpurities into colorless ones. Sugar bleached white by this sulfitationprocess is called "mill white", "plantation white", and"crystal sugar".

REFINING

In sugar refining, raw sugar isfurther purified. It is first mixed with heavy syrup and then centrifugedclean. This process is called 'affination'; its purpose is to wash away theouter coating of the raw sugar crystals, which is less pure than the crystalinterior. The remaining sugar is then dissolved to make syrup, about 70 percentby weight solids.

The sugar solution is clarified bythe addition of phosphoric acid and calcium hydroxide, which combine toprecipitate calcium phosphate. The calcium phosphate particles entrap someimpurities and absorb others, and then float to the top of the tank, where theycan be skimmed off. An alternative to this "phosphatation" techniqueis 'carbonatation,' which is similar, but uses carbon dioxide and calciumhydroxide to produce a calcium carbonate precipitate.

After any remaining solids arefiltered out, the clarified syrup is decolorized by filtration through a bed ofactivated carbon; bone char was traditionally used in this role, but its use isno longer common. Some remaining colour-forming impurities adsorb to the carbonbed. The purified syrup is then concentrated to supersaturation and repeatedlycrystallized under vacuum, to produce white refined sugar.

 As in a sugar mill, the sugar crystals areseparated from the molasses by centrifuging. Additional sugar is recovered byblending the remaining syrup with the washings from affination and againcrystallizing to produce brown sugar. When no more sugar can be economicallyrecovered, the final molasses still contains 20–30 percent sucrose and 15–25percent glucose and fructose.

To produce granulated sugar, in whichthe individual sugar grains do not clump together, sugar must be dried. Dryingis accomplished first by drying the sugar in a hot rotary dryer, and then byconditioning the sugar by blowing cool air through it for several days.

WASTE CHARACTESISTICS

The main air emissions from sugar processing and refiningresult primarily from the combustion of bagasse (the fiber residue of sugarcane), fuel oil, or coal. Other air emission sources include juice fermentationunits, evaporators, and sulfitation units.

Sugar manufacturing effluents typically have biochemicaloxygen demand (BOD) of 1,700–6,600 milligrams per liter (mg/l) in untreatedeffluent from cane processing and 4,000–7,000 mg/l from beet processing;chemical oxygen demand (COD) of 2,300–8,000 mg/l from cane processing and up to10,000 mg/l from beet processing; total suspended solids of up to 5,000 mg/l;and high ammonium content.

 The wastewater maycontain pathogens from contaminated materials or production processes. A sugarmill often generates odor and dust, which need to be controlled. Most of thesolid wastes can be processed into other products and by-products. In somecases, pesticides may be present in the sugar cane rinse liquids.

INDUSTRY SECTOR GUIDELINES

• Reduce product losses to less than 10% by better productioncontrol. Perform sugar auditing.

• Minimize storage time for juice and other intermediateproducts to reduce product losses and discharge of product into the wastewater stream.

• Give preference to less polluting clarification processessuch as those using bentonite instead of sulfite for the manufacture of white sugar.

• Collect waste product for use in other industries—forexample, bagasse for use in paper mills and as fuel. Cogeneration systems forlarge sugar mills generate electricity for sale. Beet chips can be used asanimal feed.

• Optimize the use of water and cleaning chemicals. Procurecane washed in the field. Prefer the use of dry cleaning methods.

• Recirculate cooling waters. Continuous sampling andmeasurement of key production parameters allow production losses to beidentified and reduced, thus reducing the waste load. Fermentation processesand juice handling are the main sources of leakage. Odor problems can usuallybe prevented with good hygiene and storage practices.

TREATMENTTECHNOLOGY

·                   Pretreatmentof effluents consists of screening and aeration, normally followed bybiological treatment.

·                   Ifspace is available, land treatment or pond systems are potential treatmentmethods. Other possible biological treatment systems include activated sludgeand anaerobic systems. Which can achieve a reduction in the BOD level of over95%. Odor control by ventilation and sanitation may be required forfermentation and juice-processing areas.

·                   Biofiltersmay be used for controlling odor. Cyclones, scrubbers, and electrostaticprecipitators are used for dust control. annual operating hours.

Boiling heat transfer

        Heat transfer in boiling fluids is complex but of considerable technical importance. It is characterized by an s-shaped curve relating heat flux to surface temperature difference (see say Kay & Nedderman 'Fluid Mechanics & Transfer Processes', CUP, 1985, p529).
     
         At low driving temperatures, no boiling occurs and the heat transfer rate is controlled by the usual single-phase mechanisms. As the surface temperature is increased, local boiling occurs and vapour bubbles nucleate, grow into the surrounding cooler fluid, and collapse. This is sub-cooled nucleate boiling and is a very efficient heat transfer mechanism.
   
           At high bubble generation rates the bubbles begin to interfere and the heat flux no longer increases rapidly with surface temperature (this is the departure from nucleate boiling DNB). At higher temperatures still, a maximum in the heat flux is reached (the critical heat flux). The regime of falling heat transfer which follows is not easy to study but is believed to be characterised by alternate periods of nucleate and film boiling. Nucleate boiling slowing the heat transfer due to gas phase {bubbles} creation on the heater surface, as mentioned, gas phase thermal conductivity is much lower than liquid phase thermal conductivity, so the outcome is a kind of "gas thermal barrier".
  
           At higher temperatures still, the hydro dynamically quieter regime of film boiling is reached. Heat fluxes across the stable vapor layers are low, but rise slowly with temperature. Any contact between fluid and the surface which may be seen probably leads to the extremely rapid .
 
Definitions/Terminology
 Saturation temperature (Tsat ) - boiling point temperature at prevailing pressure. In case of a mixture this will be bubble point temperature
 
Superheat - Excess temperature over the5 saturation value (T - Tsat);6 Wall superheat = (Twall - Tsat)7 Subcooling = (Tsat - T )8 Quality: Vapour phase mass fraction, ratio of9 vapour flowrate to the total flow rate.

Biodiesel

Biodiesel is a renewable fuel manufactured from vegetable oils, animal fats, and recycled
cooking oils. Biodiesel offers many advantages:
• It is renewable.
• It is energy efficient.
• It displaces petroleum derived diesel fuel.
• It can be used in most diesel equipment with no or only minor modifications.
• It can reduce global warming gas emissions.
• It can reduce tailpipe emissions, including air toxics.
• It is nontoxic, biodegradable, and suitable for sensitive environments.
• It is made in the United States from either agricultural or recycled resources.
• It can be easy to use if you follow these guidelines.



Biodiesel is a diesel replacement fuel that is manufactured from vegetable oils, recycled cooking greases or oils, or animal fats. Because plants produce oils from sunlight and air, and can do so year after year on cropland, these oils are renewable. Animal fats are produced when the animal consumes plant oils and other fats, and they too are renewable. Used cooking oils are mostly made from vegetable oils, but may also contain animal fats. Used cooking oils are both recycled and renewable.

The biodiesel manufacturing process converts oils and fats into chemicals called long chain mono alkyl esters, or biodiesel. These chemicals are also referred to as fatty acid methyl esters or FAME. In the manufacturing process, 100 pounds of oils or fats are reacted with 10 pounds of a short chain alcohol (usually methanol) in the presence of a catalyst (usually sodium or potassium hydroxide) to form 100 pounds of biodiesel and 10 pounds of glycerine. Glycerine is a sugar, and is a co-product of the biodiesel process.


Benefits of Biodiesel Use
Biodiesel Displaces Imported Petroleum
The fossil fuel energy required to produce biodiesel from soybean oil is only a fraction
(31%) of the energy contained in one gallon of the fuel.
You get 3.2 units of fuel energy from biodiesel for every unit of fossil energy used to produce the fuel. That estimate includes the energy used in diesel farm equipment and transportation equipment (trucks, locomotives), fossil fuels used to produce fertilizers and pesticides, fossil fuels used to produce steam and electricity, and methanol used in the manufacturing process. Because biodiesel is an energy-efficient fuel, it can extend petroleum supplies and makes for
sound state or federal energy policy.


Biodiesel Reduces Emissions

When biodiesel displaces petroleum, it reduces global warming gas emissions such as carbon dioxide (CO2). When plants like soybeans grow they take CO2 from the air to make the stems, roots, leaves, and seeds (soybeans). After the oil is extracted from the soybeans, it is converted into biodiesel and when burned produces CO2 and other emissions, which return to the atmosphere. This cycle does not add to the net CO2 concentration in the air because the next soybean crop will reuse the CO2 in order to grow.


Biodiesel and Human Health
Some PM and HC emissions from diesel fuel combustion are toxic or are suspected of
causing cancer and other life threatening illnesses. Using B100 can eliminate as much as 90% of these “air toxics.” B20 reduces air toxics by 20% to 40%. The effects of biodiese on air toxics are supported by numerous studies, starting with the former Bureau of Mines Center for Diesel Research at the University of Minnesota. The Department of Energy (DOE) conducted similar research through the University of Idaho, Southwest Research Institute, and the Montana Department of Environmental Quality. The National Biodiesel Board conducted Tier I and Tier II Health Effects Studies that also support these claims.

Biodiesel Improves Lubricity
By 2006, all U.S. highway diesel will contain less than 15 ppm sulfur—ultra low sulfur diesel fuel (ULSD). Currently highway diesel contains 500 ppm sulfur (or less). Biodiesel typically contains less than 15 parts per million (ppm) sulfur (sometimes as low as zero). Some biodiesel produced today may exceed 15 ppm sulfur, and those producers will be required to reduce those levels by 2006 if the biodiesel is sold into on-road markets.


Biodiesel is Easy to Use
And last, but maybe not least, the biggest benefit to using biodiesel is that it is easy. In blends of B20 or less, it is literally a “drop in” technology. No new equipment and no equipment modifications are necessary. B20 can be stored in diesel fuel tanks and pumped with diesel equipment.