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This research was aimed at analyzing energy utilization in sunglass industry furnace .Data was collected from various units that constitute the furnace operation. Useful results were obtained from the analysis of the data collected. The results revealed that total energy produced was
52.642MW, energy consumed was 22.4MW.This indicated a loss of
30.242MW and furnace efficiency of 42.56%.The number of factors: flue gas losses, moisture present in fuel and evaporation of water due to presence of hydrogen. solutions were suggested which included further
pre-heating of combustion air, pre-heating of raw material and reduction of overall heat transfer coefficient
All heat treatment processes consist of three steps: generation, holding time (during which the temperature is kept constant) and cooling. The temperature kept during the holding time is usually very high, sometimes up to 1500°C, and the holding time can be up to several hours.
This taken into account, it is obvious that a large amount of energy is
needed for the processes and this reflects in a large energy cost.
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Driven by today’s increasing energy prices and implemented energy policies, energy efficiency measures have become a top priority for large energy consuming companies. The idea of this project is to study energy utilization especially with regard to an industrial furnace in sunglass limited Kaduna state Nigeria. Based on the study, recommendations will be made on how to improve the energy utilization as well as improving the efficiency of the furnace. The main form of energy [fuel] used is Low Pour Fuel Oil [L.P.F.O] and automotive gasoline oil [A.G.O] i.e. diesel oil .Sunglass limited furnace oil consumption from 2004 to 2013 was 42,508,800 kl.
The furnace consumed 100% of the oil [L.P.F.O.] used in the industry.
Glass melting furnaces are energized by fossil oil or electricity. High energy cost, tight environmental regulations and severe competition amongst glass manufacturers have resulted to the emergence of several solutions to reduce the fuel consumption of these furnaces. Inspite of the current advancement in energy reduction, there is still a long way to achieve the ultimate goals of glass production: enhancing thermal efficiency, minimizing environmental impact, and maintaining glass quality. The problem is more severe for existing furnaces operating in poor thermal conditions around the world. A lot of research has been carried out to improve of glass melting furnaces. Some works have employed simulation approaches to analyze the effect of different factors on heat consumptions in glass furnaces. Other works utilize the following innovative methods to improve the thermal performance of glass furnaces. The methods range from
applying new burners and heat recovery systems for pre heating the
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combustion air and raw material, to considering new geometrics of combustion space and its elements.
The data used in the research is from the detailed information of energy utilization in the furnace operation. Data for fuel/energy consumption was collected for a period of ten years.
The process of manufacturing quality glass comprise of six basic steps.
i) material selection
ii) Batch operation i.e weighing and mixing raw materials iii) Melting and refining Raw
iv) Conditioning v) Forming
vi) Post- processing I. e annealing, tempering or coating.
The raw materials for glass production are as follows; silica sand, limestone, dolomite, feldspar, sodium sulphate, selenium, charcoal, iron chromate, carborn90 and cullet.
The glass composition determines the physical and chemical properties of the glass container. For melting and refining purposes, sunglass uses a continuously operated tank furnace commonly use for the melting of glass. The furnace [tank] consists of a batch charging area [dog house], attached
to a refractory basin, covered by a refractory super structure [crown].
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The common heating methods are combustion heating[oxy-fuel, air fuel burners].To keep the glass level constant, the mixture of batch and cullet is continuously charged into the glass melting furnace to compensate for the glass withdrawn.
The process of refining and melting takes place in the melting chamber. During this process the batch of molten glass is freed of bubbles, homogenized, and heat condition before the glass is introduced into the fore hearth.
Furnace is by definition a device for heating materials and therefore a user of energy. Heating furnaces can be divided into batch-type (Job at stationary position) and continuous type (large volume of work output at regular intervals). The types of batch furnace include box, bogie, cover, etc. For mass production, continuous furnaces are used in general. The types of continuous furnaces include pusher-type furnace, walking hearth-type furnace, rotary hearth and walking beam-type furnace.
The primary energy required for reheating / heat treatment (say annealing)
furnaces are in the form of Furnace oil, LSHS, LDO or electricity
The various losses that occur in the fuel fired furnace are listed below.
I. Heat lost through exhaust gases either as sensible heat or as incomplete combustion
II. Heat loss through furnace walls and hearth
III. Heat loss to the surroundings by radiation and convection from the outer surface of the walls
IV. Heat loss through gases leaking through cracks, openings and doors.
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Energy costs are significant in the glass industry and account for 15% of the industry costs. (GMIC, Glass Manufacturing Industry Council,2002). In the glass industry, energy is consumed in the form of fuel and electricity. A critical look at the energy (fuel) consumption for the past ten years in sunglass limited clearly indicates that there is increase in consumption rate each year, all things being equal.
The data used in this research work was collected from the industry furnace Original Equipment Manufacturer (OEM) and the following were the data obtained
Flue gas temperature – 1120oC Stack temperature – 420oC Consumption of fuel / hour – 492 kJ/hr
Temperature of raw material – 300K
The temperature of the ambient air- 40oC The temperature of preheated air – 1373oC Specific gravity of fuel – 0.92
Calorific value of fuel- 418680kJ/kg
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Capacity of furnace tons / day -100 tons/day
Fuel flow rate – 1880m2/h
Gross heat of combustion of fuel oil- 24010417kcal/kg
YEAR | MONTH | AVERAGE CONSUMPTION IN Kl/yr | FUEL CONSUMPTION IN KL/YEAR |
2004 | JAN – DEC | 420 | 3,628,800 |
2005 | JAN – DEC | 440 | 3,801,600 |
2006 | JAN – DEC | 430 | 3,715,200 |
2007 | JAN – DEC | 460 | 3,974,400 |
2008 | JAN – DEC | 450 | 3,888,000 |
2009 | JAN – DEC | 460 | 3,974,400 |
2010 | JAN – DEC | 540 | 4,665,600 |
2011 | JAN – DEC | 570 | 4,924,800 |
2012 | JAN – DEC | 580 | 5,011,200 |
2013 | JAN – DEC | 570 | 4,924,800 |
TOTAL | ,9204 | 42,508,800 |
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Year | Month | CONSUMPTION IN KILOLITRES | |||
Year | Month | Day | Week | Month | Year |
2004 | JAN-DEC | 5 | 35 | 150 | 1800 |
2005 2006 | - - | 6 5 | 42 35 | 180 150 | 2160 1800 |
2007 | - | 5 | 35 | 150 | 1800 |
2008 | - | 7 | 49 | 210 | 2520 |
2009 | - | 5 | 35 | 150 | 1800 |
2010 | - | 4 | 28 | 120 | 1440 |
2011 | - | 5 | 35 | 150 | 1800 |
2012 | - | 5 | 35 | 150 | 1800 |
2013 | - | 6 | 42 | 180 | 2160 |
Heat balance helps us to numerically understand the present heat loss and efficiency and improve the furnace operation using these data. Thus, preparation of heat balance is a pre-requirement for assessing energy conservation potential.
1. Furnace Efficiency, η = 𝐻𝐸𝐴𝑇 𝑂𝑈𝑇𝑃𝑈𝑇
𝐻𝐸𝐴𝑇 𝐼𝑁𝑃𝑈𝑇
𝑋 100
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= ℎ𝑒𝑎𝑡 𝑖𝑛 𝑠𝑡𝑜𝑐𝑘(𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙)(𝑘𝐶𝑎𝑙𝑠) x 100
ℎ𝑒𝑎𝑡 𝑖𝑛 𝑓𝑢𝑒𝑙/𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑖𝑡𝑦(𝑘𝐶𝑎𝑙𝑠)
2. Specific Energy Consumption = 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑟 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑
𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑝𝑟𝑜𝑐𝑒𝑠𝑠𝑒𝑑
.
The efficiency of the furnace can be computed by measuring the amount of fuel consumed per unit weight of material produced from the furnace
Thermal efficiency of the furnace = 𝐻𝑒𝑎𝑡 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑡𝑜𝑐𝑘
𝐻𝑒𝑎𝑡 𝑖𝑛 𝑡ℎ𝑒 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑
𝑸 = 𝒎 × 𝑪𝑷(𝒕𝟐 − 𝒕𝟏 )
Where
Q = Quantity of heat in Kilojoule
m = Weight of the material in kilogram
C = Mean specific heat, kJ/KgoC
p
o
t = Final temperature desired, C
2
o
t Initial temperature of the charge before it enters the furnace, C
1 =
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The following measurements are to be made for doing the energy balance in oil fired reheating furnaces (e.g. Heating Furnace)
i) Weight of stock / Number of billets heated ii) Temperature of furnace walls, roof etc
iii) Flue gas temperature iv) Flue gas analysis
v) Fuel Oil consumption
Instruments like infrared thermometer, fuel consumption monitor, surface thermocouple and other measuring devices are required to measure the above parameters. Reference manual should be referred for data like specific heat, humidity etc.
The enthalpies of fresh air, fuel and raw material, while its outlets are glass melt heat losses through combustion space and glass tank refractory and stack flue. The energy balance equations of the control volume as well as regenerator and raw material pre-heater,
𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑓𝑟𝑒𝑠ℎ 𝑎𝑖𝑟 = 𝑄𝑚𝑒𝑙𝑡𝑖𝑛𝑔 + 𝑄𝑔𝑙𝑎𝑠𝑠 𝑡𝑎𝑛𝑘 𝑙𝑜𝑠𝑠 + 𝑄𝑐𝑜𝑚𝑏𝑢𝑠𝑡𝑖𝑜𝑛 𝑠𝑝𝑎𝑐𝑒 𝑙𝑜𝑠𝑠
+ 𝑄𝑆𝑡𝑎𝑐𝑘 𝑙𝑜𝑠𝑠 …………………………………………1
The control volume of a glass melting plant is shown in Fig. 1. The
control volume's inlets are
𝑄𝑓𝑙𝑢𝑒 + 𝑄𝑓𝑟𝑒𝑠ℎ 𝑎𝑖𝑟 = 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑑 + 𝑄𝑟𝑒𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑜𝑟 𝑒𝑥𝑖𝑡 … … … … … . … . .2
Q 𝑄𝑟𝑒𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑜𝑟 𝑒𝑥𝑖𝑡 = 𝑄𝑠𝑡𝑎𝑐𝑘 𝑙𝑜𝑠𝑠 + 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑑 𝑟𝑎𝑤 …………………3
Therefore the energy balance equation of furnace can be represented in
the form of Eq. (5).
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𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑟 - 𝑄𝑓𝑙𝑢𝑒 = 𝑄𝑚𝑒𝑙𝑡𝑖𝑛𝑔 + 𝑄𝑔𝑙𝑎𝑠𝑠 𝑡𝑎𝑛𝑘 𝑙𝑜𝑠𝑠 +
𝑄𝑐𝑜𝑚𝑏𝑢𝑠𝑡𝑖𝑜𝑛 𝑠𝑝𝑎𝑐𝑒 𝑙𝑜𝑠𝑠 - 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑑 𝑟𝑎𝑤 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 ………………………4
𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑟 - 𝑄𝑓𝑙𝑢𝑒 x 𝑢𝑐𝑜𝑚𝑏𝑢𝑠𝑖𝑜𝑛 = 𝑄𝑚𝑒𝑙𝑛𝑔 + 𝑄𝑔𝑙𝑎𝑠𝑠 𝑡𝑎𝑛𝑘 𝑙𝑜𝑠𝑠 -
𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑑 𝑟𝑎𝑤 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 ……………………… ………………………….5
Figure 3.1:. The control volume of a glass melting plant.
Group. | Parameter | Value |
Combustion | Fuel flow rate | 1880 𝑚3/h |
excess air ratio | 20% | |
𝑁2 /𝑂2 | 79�21=3.76 |
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Temp. preheated air | 1373k | |
Temp. of flue gas | 1120k | |
fuel flow rate measured | Mass of raw materials | 100 𝑡𝑜𝑛�𝑑𝑎𝑦 |
Temp preheated raw material | 300k | |
Cullet % | 60 % | |
Wall losses | µ tank | 5 𝑤�𝑚2𝑘 |
Glass tank loss | 1.62 mw | |
µ chamber | 10𝑤�𝑚2𝑘 | |
Combustion space | 4.64 mw |
Table 3.4 CONSUMPTION IN EACH UNIT
Component | Consumption in MW |
Glass melting | 4.4 |
Regenerator | 7.4 |
Glass tank loss | 4.6 |
Stack flue loss | 1.6 |
Combustion | 4.4 |
Total | 22.4 |
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An oil-fired reheating furnace in sunglass limited has an operating
o
temperature of around 1500 C. Average fuel consumption is 492
o
liters/hour. The flue gas exit temperature after air pre-heater is 1120
C. Air
is preheated from ambient temperature of 40
o
C to 190
o
C through an air
pre-heater. The furnace has 460 mm thick wall on the billet extraction outlet side, which is 1 m in height and 1 m wide. The other data are as given
below.
o
Flue gas temperature after air pre heater = 1120 C
o
Ambient temperature = 40 C
o
Preheated air temperature = 190 C
Specific gravity of oil = 0.92
Average fuel oil consumption = 492 Litres / hr
= 492 x 0.92 =452.64 kg/hr
Calorific value of oil = 10000 kCal/kg =418680kJ/kg
Average O
2
percentage in flue gas = 12%
Weight of stock = 4166.67 kg/hr
Specific heat of Billet = 0.12 kCal/kg/
0
C =0.502kJ/kg/o C
o
Surface temperature of roof and side walls = 366 C
o
Surface temperature other than heating and soaking zone = 85 C
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Excess air = 𝑂2%
21−𝑂2%
𝑋 100 (Where O
2
is the % of oxygen in flue gas
= 12%)
12
21−12
ₓ100
= 133% excess air
Theoretical air required to burn 1 kg of oil = 14 kg (Typical value for all fuel oil)
Total air supplied = Theoretical air x (1 + excess air/100) Total air supplied = 14 x 2.33 kg / kg of oil
= 32.62 kg / kg of oil
Sensible heat loss = m x C
p
x ΔT
m = Weight of flue gas
= Actual mass of air supplied / kg of fuel + mass of fuel (1kg)
= 32.62 + 1.0
= 33.62 kg / kg of oil.
C = Specific heat of flue gas
p
o
= 0.24 kCal/kg C =1.004kJ/kg/oC
ΔT = Temperature difference
Heat loss = m x C
p
x ΔT
= 33.62 x 0.24 x (1120– 40)
= 8714.304 kCal / kg of oil
% Heat loss in flue gas = 8714.304 x 100/10000
= 87.14%
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{584+0.45 (𝑇𝑓𝑔−𝑇𝑎𝑚𝑏)}100
% Loss = 𝑚
Where,
𝐺𝐶𝑉 𝑜𝑓 𝐹𝑢𝑒𝑙
M - % Moisture of in 1 kg of fuel oil (0.15 kg/kg of fuel oil)
T - Flue Gas Temperature
fg
T
amb
- Ambient temperature
GCV - Gross Calorific Value of Fuel
% Loss = 0.15{584+0.45 (750−40)}
1000
𝑥 100
= 1.36%
9 x H
2
{584 + 0.45 (T
-T )}
fg amb
% Loss = 9 × 𝐻2
�584+0.45 (𝑇𝑓𝑔 −𝑇𝑎𝑚𝑏 )� × 100
𝐺𝐶𝑉 𝑂𝑓 𝐹𝑢𝑒𝑙
GCV of Fuel
Where, H
2
– % of H
2
in 1 kg of fuel oil (0.1123 kg/kg of fuel oil)
= 9 × 0.1123 (584+0.45 (750−40)
1000
× 100
= 9.13 %
Source:Bureau of Energy Efficiency. www.pcra.org
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The reheating furnace in example has 460mm thick wall (X) on the billet extraction outlet side, which is 1m height (D) and 1m wide. With furnace
0
temperature of 1340
C, the quantity (Q) of radiation heat loss from the
opening is calculated as follows:
The shape of the opening is square and D/X = 1/0.46 = 2.17
The factor of radiation = 0.71
o
Black body radiation corresponding to 1340 C = 36.00 kCal/cm
Figure 4.1 On black body radiation)
Area of opening = 100 cm x 100 cm
2
/hr (Refer
2
= 10000 cm
Emissivity =0.8
Total heat loss = Black body radiation x area of opening x factor of radiation x emissivity
=36 x 10000 x 0.71 x 0.8
= 204480 kCal/hr
Equivalent Oil loss = 204480/10,000
= 20.45 kg/hr
% of heat loss = 20.45 /368 x 100
= 5.56%
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YEAR | MONTH | AV.CONP T.IN ltr/hr | FUEL CONPT. IN kl/yr | COST OF oil/ltr | TOTAL COST |
2004 | JAN- DEC. | 420 | 3,628,800 | 67 | 243,129,600 |
2005 | - | 440 | 3,801,600 | 71 | 263,779,200 |
2006 | - | 430 | 3,715,200 | 76 | 282,355,200 |
2007 | - | 460 | 3,974,400 | 79 | 313,977,600 |
2008 | - | 450 | 3,888,000 | 82 | 318,816,000 |
2009 | - | 460 | 3,974,400 | 84 | 333,849,600 |
2010 | - | 540 | 4,665,600 | 91 | 424,569,600 |
2011 | - | 570 | 4,924,800 | 96 | 472,780,800 |
2012 | - | 580 | 5,011,200 | 102 | 511,142,400 |
2013 | - | 570 | 4,924,800 | 105 | 517,104,000 |
TOTAL | 4,920 | 42,508,800 | 3,681,504,000 |
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YEAR | MONTH | AV CONPT /DAY(kl) | CONSU MT/WEE K(kl) | CONSUMI ON/MONTH (kl) | CONSUMT /YEAR(kl) | PRICE/ LTR( | TOTAL COST/YEAR |
2004 | JAN- DEC | 5 | 35 | 150 | 1800 | 110 | 198000000 |
2005 | - | 6 | 42 | 180 | 2160 | 115 | 248400000 |
2006 | - | 5 | 35 | 150 | 1800 | 125 | 225000000 |
2007 | - | 5 | 35 | 150 | 1800 | 130 | 234400000 |
2008 | - | 7 | 49 | 210 | 2520 | 135 | 340200000 |
2009 | - | 5 | 35 | 150 | 1800 | 135 | 243000000 |
2010 | - | 4 | 28 | 120 | 1440 | 140 | 201600000 |
2011 | - | 5 | 35 | 150 | 1800 | 145 | 261000000 |
2012 | - | 5 | 35 | 150 | 1800 | 150 | 270000000 |
2013 | - | 6 | 42 | 180 | 2160 | 150 | 324000000 |
2344000000 |
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Loss Component | Heat Loss | % |
Sensible heat loss in Flue gas | 34685.048kJ/kg | 87.14 |
Loss due to evaporation of moisture | 0.013kJ/kg | 1.36 |
Loss due to evaporation of water | 0.0913kJ/kg | 9.13 |
Loss due to openings | 0.0056k/kg | 0.56 |
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100
90
80
70
60
50
40
30
20
10
0
SHL LDEM LDEW LDO
Series 1
Fig:
4.3 Graphical Representations of Results
Total energy loss =30.242MW Total cost of oil=3,681,504,000
Percentage loss = 57.44
Price loss = 0.5744x3,681,504,000
= 2,114,655,989
Table 3.4 Percentage of Consumption
Component | Consumption in MW | % energy consumption |
Glass melting | 4.4 | 4.4 𝑋 100 = 20% 22.4 |
Regenerator | 7.4 | 7.4 𝑋 100 = 32% 22.4 |
Glass tank loss | 4.6 | 4.6 𝑋 100 = 21% 22.4 |
Stack flue loss | 1.6 | 1.6 𝑋 100 = 7% 22.4 |
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Combustion | 4.4 | 4.4 𝑋 100 = 20% 22.4 |
Total | 22.4 | 100% |
melting stack loss regenerator glass tank loss combution space loss
21%
20%
7%
20%
32%
Fig. 4.3 Pie chart
Applying the above terms, the heat consumption associated with different components of the furnace was computed and displayed (see Fig. 3.2). It can be seen that 4.4 MW (20%) of total energy is consumed for glass melting and another 7.4 MW (32%) is recovered in regenerator. The rest of energy is lost through the combustion space refractory, the glass tank refractory and the stack flue as 4.6 MW (21%), 1.6 MW (7%) and 4.4 MW
(20%) respectively.
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The values obtained from the results above are calculated as shown below:
1. Energy lost through the combustion refractory
Using 𝑄= 𝐾𝐴(𝑇1−𝑇𝑜)
𝑡
𝑄 = heat loss at combustion space
K= Coefficient of thermal conductivity= 10 w/m2 k
Ti= Temperature of preheated air = 1373k
To= Temperature of flue gas = 1220k
T =Thickness 313
A=area 751m2
𝑄 =10×751×(1373−1120)
313
𝑄=6070.38 Joules
Converting to watt
=6070.38×764
=4637770.32W
𝑄 combustion space ⸗ 4.64MW
The other results for energy lost through regenerator, glass tank loss, stack
loss, and melting are obtained via same procedure above.
𝑄𝑓𝑢𝑒𝑙 + 𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑟 - 𝑄𝑓𝑙𝑢𝑒 x 𝑢𝑐𝑜𝑚𝑏𝑢𝑠𝑖𝑜𝑛 = 𝑄𝑚𝑒𝑙𝑡𝑛𝑔 + 𝑄𝑔𝑙𝑎𝑠𝑠 𝑡𝑎𝑛𝑘 𝑙𝑜𝑠𝑠 -
𝑄𝑝𝑟𝑒ℎ𝑒𝑎𝑡𝑒𝑑 𝑟𝑎𝑤 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 ……………………… ………………………….5
Mass of fuel =452.64kg/hr
Calorific value (CV) =418680kJ/kg
Qfuel = mass of fuel x cv
=452.64 x 418680
=189511315kJ/hr
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=52.642MW
Total energy produced by the combustion LPFO =52.642MW Total energy consumed in various units = 22.4MW
Energy loss = 52.642 – 22.4
= 30.242MW
Efficiency = ℎ𝑒𝑎𝑡 𝑜𝑢𝑡𝑝𝑢𝑡 x100
ℎ𝑒𝑎𝑡 𝑖𝑛𝑝𝑢𝑡
= 22.4
52.642
x 100
= 42.56%
SEC = 𝑞𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑟 𝑓𝑢𝑒𝑙 𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑
𝑞𝑢𝑎𝑛𝑡𝑖𝑡𝑦 𝑜𝑓 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙𝑠 𝑝𝑟𝑜𝑐𝑒𝑠𝑠𝑒𝑑
= 22.4
452.64
(452.64 is from data analysis)
= 0.049kJ/hr
The energy balance calculations above clearly indicates a large difference between energy supplied and energy utilized. The excessive energy loss depicts drastic reduction in furnace efficiency as shown above and consequently increased expenditure on fuel.
Simulation of glass melting furnaces can be used as a good tool to analyse the effect of different factors on the fuel consumption as regards to energy utilization in Sunglass limited. In this work, the temperature of preheated
air, the temperature of raw material, and the overall heat transfer coefficient
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International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 1469
ISSN 2229-5518
of combustion space are varied over a wide range to analyse the sensitivity of fuel consumption. The results indicate a large energy loss, which could be a combination of several factors including: insufficient preheating of combustion air, non-preheating of raw materials and excessive heat transfer coefficient.
A combination of different methods could be applied to achieve further fuel reduction. Sunglass Limited should therefore as a matter of fact, consider the following:
i. Further preheating of combustion air
ii. Preheating of raw materials, which at present is not done?
iii. Decreasing the overall heat transfer coefficient. This is very necessary.
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Abbassi A., Khoshmanesh K Numerical Simulation and Experimental Analysis of an Industrial Glass Melting Furnace. Submitted to Applied Thermal Energy Journal, 2006.Authorized licensed use limited to: IEEE Xplore. Downloaded on March 12, 2009 at 22:57 from IEEE Xplore. Restrictions apply.
Application to a glass furnace. In: 10th Mediterranean Conference on
Control and Automation, Lisbon, Portugal, 2002.
Avdic F. Application of the porous medium gas combustion techniqueto household heating systems with additional heating systems. PhD. Thesis, Erlangen University, 2004.
Burner technology. In 5th international conference on technology and combustion for a clean environment, Lisbon, Portugal, 1999.
Carvalho M. G. Computer simulation of a glass furnace, PhD thesis, London University, 1983.
Elich J. J., Koppers G. A. A., Wieringa J. A. (1993)”Energy-saving effects of surface-structured walls in a glass melting furnace” Journal of Institute of Energy,; 66:71–78.
Glass-melting Furnaces, Cement Kilns and Baking Ovens. Applied Thermal
Engineering, 1997; 17(8/10).
IJSER © 2014 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 1471
ISSN 2229-5518
H. Kobayashi, K.T. Wu, L. H. Switzer, S. Martinez, R. Giudici, CO2
Reduction from Glass Melting Furnaces by Oxy-fuel Firing Combined With
Batch/Cullet Preheating, 2005.
Herzog,J.,SettimoR.J. (1992) Energy-saving cullet preheater. Glass
Industry,; 73(10):36–39.
Integrated batch and cullet preheating system, Department of energy, Office of industrial technologies, 1997.
Karlsruhe, Germany, (1992), Plum S., Graf P., Beckers M. Advanced heating techniques for glass melting. Eindhoven Technical University, March 2002. p. 323–339. 18.
Leimkuhler, J. Raw material preheating and integrated waste heat utilization in the glass industry. Sprechsaal, 1992; 125(5):292–298. McConnell R. R., Goodson R. E. Modeling of glass furnace design for improved energy efficiency. Glass technology, 1979; 20(3):100-106.
Wu, Y., Cooper A. R. Batch and cullet preheating can save energy. Glass
Industry, 1992; 73(8):10–13.
M. F. G. Cremers Heat Transfer of Oxy-Fuel Flames to Glass: The Role of
Chemistry and Radiation, PhD. Thesis, Eindhoven University,2006.
Simpson N. G. Oxygen technologies for recovery and boosting of glass furnaces. See also www.glassmediaonline.com
Pina J. M., Lima P. U. An operation system for industrial processes:
IJSER © 2014 http://www.ijser.org
International Journal of Scientific & Engineering Research, Volume 5, Issue 12, December-2014 1472
ISSN 2229-5518
Industrial furnaces [vol.2] by W.Trinks John wiley and sons Inc. New york
1925.
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