Improvement of Boiler Efficiency Using Bagasse Dryer


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International Research Journal of Engineering and Technology (IRJET)

Volume: 04 Issue: 10 | Oct -2017

www.irjet.net

e-ISSN: 2395-0056 p-ISSN: 2395-0072

Improvement of Boiler Efficiency Using Bagasse Dryer

Salunke V.V.1, Deshmukh K.B.2, Garud R.P.3, Patil A.S.4 Prof. Kulkarni S.C.5

1,2,3,4U G Student Dept. of Mechanical Engineering, S B Patil college of Engineering Indapur, Pune

5 Professor Dept. of Mechanical Engg., S B Patil college of Engineering Indapur, Pune

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Abstract - In most sugar industry, sugarcane bagasse is used

of bagasse and the total available heat, therefore, varies

as fuel to generate steam for sugar Milling and electricity

inversely with the moisture content. Furthermore, the

generation. It consists of cellulose, hemicellulose, lignin, ash

portion of heat which is used to evaporate the bagasse

and moisture Content. The bagasse Moisture content is an

moisture and to superheat the resulting steam to the

important parameter to control combustion in boilers.

temperature of the flue gases must be deducted from the

Simulated bagasse was used to monitor the effects of

total available heat. (Each kg of water in bagasse requires 418

moisture content on gross calorific value (GCV) and net

kJ (100 kcal) to reach its boiling point and

calorific Value (NCV) and equilibrium analysis. So burning of

2,259 kJ (540 kcal) to convert it into steam.

bagasse at suitable level of moisture is Essential from the

viewpoint of boiler performance.

1.1Problem Statement

Key Words: Bagasse, Fuel, Sugar cane residue, moisture content.
1 Introduction:-
Sugarcane based industry has a tremendous potential and its future is bright in many countries including Egypt. It is an old idea to concentrate on producing sugar alone from sugarcane. The by- products of sugar industry (such as bagasse, filter cake and molasses) today attract as much attention as the conventional main product, sugar. The trend in the sugar producing nations now is to concentrate more and more on by-products - thus rendering sugar ironically, as the by-product.
In the past, bagasse was considered as waste material. Today, bagasse has become valuable material. Aside from being used as a fuel, it is a starting material for different products such as paper, paper board, fiberboard, particle board, animal feed, etc. In Brazil, today’s leader of sugar industry, the emphasis is on developing a variety of cane having up to 25 % of fibre content since more bagasse signifies higher profits.

During the combustion process in a boiler considerable amount of furnace energy is wasted in evaporating the water contained in the fresh bagasse; therefore decrease the efficiency of combustion. Due to this, it decrease the calorific value, furnace temperature, reduces stability of boilers operation, decreasing the vaporization coefficient and combustion velocity, decreasing the speed of boilers response to load changes and also increment of the losses and decreasing steam production giving rise to flue gases. So in present, work design of such model is necessary which overcomes above parameter up to some extent.
1.2 Objective
Objective of this project is to dry the wet bagasse or remove moisture in the bagasse by using bagasse dryer.
To improve the efficiency of combustion, increase the calorific value, increasing the furnace temperature, increasing the energy production, increasing the stability of boiler operation, increasing the vaporization coefficient, increasing the combustion velocity,

Moreover, in Pakistan, the price of bagasse per ton is higher than the price of sugar cane. The value of bagasse may be more than the value of sugar. So it is necessary to optimize the use of bagasse, because of the competition between its use as fuel in boilers and as starting material.
The moisture content in bagasse varies considerably with the degree of extraction, but under average conditions it may be taken as 50 % of the total weight leaving the mills (The average value of the moisture content in bagasse reaches 52 % in almost all the cane sugar factories of the Sugar and Integrated Industries Company SIIC of Egypt in the 1998 harvesting season. The higher the moisture content, the lower is the amount of combustible material per unit weight

Increasing the speed of boiler response to load changes, reduction of losses, increasing steam production, decreasing flue gases volume. So, above all efficiency improvement parameter can help to increase the output of boiler efficiency.
2. Methodology
1) Firstly determine the moisture content level in wet bagasse & also determine the calorific value & efficiency of boiler. 2) Discuss alternating methods to reduce moisture content up to large extent. 3) Selection proper method. 4) Design of bagasse dryer system.

© 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1286

International Research Journal of Engineering and Technology (IRJET)

Volume: 04 Issue: 10 | Oct -2017

www.irjet.net

e-ISSN: 2395-0056 p-ISSN: 2395-0072

5) Evaluation of bagasse dryer system. 6) Availability of various parts of dryer model. 7) Actual construction of dryer model. Testing of dryer. 8) Calculation of moisture content level in bagasse. 9) Calculation of calorific value & efficiency of boiler
2.1 Drying Mechanism
For the drying process, heat is necessary to evaporate moisture from the surface and a flow of air is needed to carry away the evaporated moisture. During drying, moisture from the interior has to migrate towards the surface, where the evaporation of moisture has to take place. Water vapor diffuses through a boundary film of air and is carried away by the surrounding air. This creates a region of lower water vapor pressure at the surface of the material and a water vapor pressure gradient is established from the moist interior of the material to the dry air. This gradient provides the driving force for the removal of water from the material. Water movement to the surface of the product may be effected due to the following mechanisms;
Liquid movement by capillary forces. Diffusion of liquid, caused by differences in the concentrations of solutes in different regions of the materials. Diffusion of liquid which is adsorbed in layers at the surface of the solid components of the material. Water vapor diffusion in air spaces within the material caused by vapor pressure gradients. Typical drying is divided into constant rate and falling rate periods.
The controlling resistance for a drying study may be of energy or mass transfer due to internal or external conditions. The drying rate in the constant rate period is determined by conditions external to the material being dried including temperature, gas velocity, total pressure and partial vapor pressure.
2.2 Drying Kinetic
For each and every product, there is a representative curve that describes the drying characteristics for that product at specific temperature, velocity and pressure conditions. This curve is referred to as the drying rate curve for a specific product. The drying rate refers to the rate of evaporation of water from the material. A plot of the drying rate versus product moisture content (MP) is called the drying rate curve. Figure 3.1.3 shows a typical drying rate curve displaying an initial constant rate period, and at the critical moisture content the drying rate begins to fall with a further decrease in moisture content.
The mechanism underlying this phenomenon depends both on the material and the drying conditions. The drying rate in the constant rate period is governed fully by the rates of external heat and mass transfer, since a film of free water is always available at the evaporating surface. The drying rate
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in this period is essentially independent of the material being dried.

3. DESIGN DATA

3.1 Data collected from Karmayogi Sahakari Sakhar Karkhana

Fuel firing Steam generation rate Steam Pressure Generated steam pressure Feed water temperature Co2 in flue gas Co in flue gas Average flue gas temperature Ambient temperature Humidity in ambient air
Surface temperature of boiler
Wind velocity around the boiler

5599.17kg/hr
21937.5kg/hr 43kg/cm2 4850C 960C 14%
0.55 1900C 310C 0.0204kg/kg
dry air 70oC
3.5m/s

3.2 Fuel Analysis (in %).

Carbon Hydrogen Oxygen Nitrogen Sulphur Ash Moisture

22.16 2.84 21.0 0 0 4 50

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International Research Journal of Engineering and Technology (IRJET)

Volume: 04 Issue: 10 | Oct -2017

www.irjet.net

e-ISSN: 2395-0056 p-ISSN: 2395-0072

3.3 Ultimate analysis of bagasse(in %):

Ash content in fuel Moisture in fuel Carbon content Hydrogen content Nitrogen content Oxygen content GCV of coal

8.63 31.6 41.65 2.0413 1.6 14.48 3501Kcal/kg

3.4 Design Of Bagasse Dryer Model In CATIA

3.5 Specification of component for experimentation

Sprocket Dryer Chain

Teeth=40 Pitch=12.7mm Diameter=161.84mm
Small steam tube=10 Length=701.04mm External
Diameter=34mm Internal Diameter=27mm Large steam
tube=2 Length=1371.6mm Outer Diameter=72mm Internal
Diameter=65mm
Length=3435mm Chain pitch=15.875mm
No of links=216

4. Boiler efficiency
The efficiency of a boiler is the energy imparted to the boiler feed water in its conversion to superheated steam as a percentage of the energy in the fuel. It can be expressed either in terms of the net or gross calorific value. Because the latent heat in the flue gas is not normally recovered, only the boiler efficiency on NCV is of practical value and the one commonly used. For the purpose of boiler calculations, calorific values must be corrected to ambient temperature. One of the standards for determining boiler efficiencies is BS 845 (Anon 1987) but there are other methods being practiced, often with different results. Whichever way it is done it is based either on the ‘direct method’ or the ‘indirect loss method’
4.1 Direct method
This method calculates boiler efficiency by using the basic efficiency formula-
η=(Energy output)/(Energy input) X 100 In order to calculate boiler efficiency by this method, we divide the total energy output of a boiler by total energy input given to the boiler, multiplied by hundred.
Calculation of direct efficiency- E= [Q (H-h)/q*GCV]*100
Where, Q= Quantity of steam generated (kg/hr) H= Enthalpy of steam (Kcal/kg) h= Enthalpy of water (kcal/kg) GCV= Gross calorific value of the fuel.
L2 = Sensible heat loss in flue gas L3 = Loss due to unburned carbon L4 = Radiation loss L5 = other losses
4.1 Result
1) The moisture reduction of bagasse is 10-15 % 2) Due to reduction of moisture of bagasse by 10-15 % the, GCV of bagasse is increased from 4522 kCal/kg at 50 % moisture to 4628 kCal/kg at 35 % bagasse moisture. 3) The boiler efficiency is improved from 69% to 81%.
5. CONCLUSION
The aim of the introduction of dryer was to reduce the moisture content in wet bagasse in order to improve boiler efficiency and reduce device costs. The obtained results show clearly that these aims were succeeded. The boiler efficiency was improved from 69% to 81%.

© 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1288

International Research Journal of Engineering and Technology (IRJET)

Volume: 04 Issue: 10 | Oct -2017

www.irjet.net

e-ISSN: 2395-0056 p-ISSN: 2395-0072

REFERENCES

1. Anthony Anukama,b,n, Sampson Mamphweli a, Prashant Reddy c, Edson Meyer a, Omobola Okoh b“Pre-processing of sugarcane bagasse for gasification in a downdraft biomass gasifier system: A comprehensive review”, “Renewable and Sustainable Energy Reviews”, 2016

2. Prof. V. V. Patil1, Prof. A.M. Patil2, Prof. P. D.
Kulkarni3,”design and development of bagasse dryer for modern jaggery house”, “International Journal of Advance Research In Science And Engineering” ,September 2014

3. Juan H. Sosa-Arnao1, Jefferson L. G. Corrêa2, Maria A.

Silva3 and Silvia A. Nebra4, “Sugar cane bagasse

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www.researchgate.net/publication/239556788,

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4. Anisha Agarwal, Vyoma Maroo, “bagasse power in
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5. International Journal of Innovative Research in Science, Engineering and Technology Vol2, Issue 5, May 2013

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Improvement of Boiler Efficiency Using Bagasse Dryer