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WASTE HEAT RECOVERY FROM FURNACE FLUE GASES USING WASTE HEAT RECOVERY BOILER SyedAmjad Ahmad*, **Saqib Ehsan, ***Muhammad UsmanBabar, ***SyedHasnainHussainb, ***Hafiz Abdul-ur-Rehmanb, ***Muharnmad Qasim *Head Mechanical Engg, * * *Students-Department of Mechanical Engineering, NFC Institute of Engineering and Fertilizer Research, Faisalabad ** Head Civil Engg. Department, NFC IE&FR, Faisalabad Correspondence Author: samjadahmad67@yahoo. com Abstract: Energy saving is one of the key issues, not only from the point of view of fuel consumption but also for the protection of global environment. So, it is imperative that a significant and concrete effort should be made for conserving energy through waste heat recovery. This research paper will address the problem of heat energy which is wasted away from furnace in the form of flue gases. The main object is to recover waste heat from the system and transfer the lost energy from the source back into the useful work and also to make the energy conversionprocess as efficient as possible. There are various techniques in use, for recovery of waste heat from various systems under different situation. This work is carried out on prototype Cupolafurnace whichis the most widely used industrial melting furnace. While a two pass fire tube Boiler is used as waste heat recovery boiler (WHRB). This paper involves the (a) calculation of energy which is wasted due to the different heat losses in furnace, (b) Recovery of the waste heat of flue gases, (c) Generation of process steam in WHRB. Some techniques are suggested in this work, in order to minimize the losses of waste heat energy, and also the suggestions forfurtherwork infuture. Keywords: Waste, Cupola furnace, Heat losses, Dust catcher, Recovery boiler. 1. Introduction Waste heat is the heat, which is generated in a process by way of fuel combustion or chemical reaction, and then "dumped" into the environment even though it could still be utilized for some useful and economic purposes. Waste heat, in most general sense, is the energy associated with the waste streams of air, gases, and liquids that leave the boundaries of a plant or building and enter into the environment. Waste heat which is rejected from a process at a temperature enough high above the ambient temperature permits the recovery of energy for some useful purposes in an economic manner. The essential quality of heat is not the amount but its "value". The strategy of how to recover this heat depends not only on the temperature of the waste heat sources but also on the economics involves behind the technology incorporated. Reay found by experiments that not only is heat recovery economical, but that it also reduces pollution. He used heat exchangers for recovering the heat [1]. Jekerle. Jiri Ormann. and Heinrich Rothenpieler. invented a waste heat boiler in 2006 which included an axial bypass pipe and multiple heat transfer pipes disposed within a cylindrical jacket [2]. Cosme Matias Meneze(CMM) group in 2005 conducted a research on heat recovery boiler and they concluded that the steam generated can be used as main stream steam[3].Schalles found that much of the heat produced in melting operation is lost to atmosphere. When this waste energy is re- used, it may save up to approximately 20% of a facility's energy cost and, in some cases, reduce emissions [4]. Tang Jinquan developed many waste heat recovery power plants (WHRPP) while serving as Chief Technical Director of Dalian East New Energy Development Co., Ltd [5]. Denmark is probably the most active energy recycler, obtaining about 55% of its energy from CHP and waste heat recovery [6]. Tugrul Ogulata discussed the utilization of waste-heat recovery in textile drying process [7]. Soylemez studied on the thermo economical optimization of Heat Pipe Heat Exchanger (HPHE) for waste heat recovery system [8, 9]. Lukitobudi, Akbarzadeh and Johnson found that high temperature steam which is generated by WHRB could be more conveniently used for some useful purpose [10]. Zainal Zakaria and Nor Ismail Hashim found that the cost of system increases due to the erosion and corrosion in boiler[ 11].Energy consumption by the system and environmental pollution can still further be reduced by designing and employing energy saving equipments. NFC-IEFR Journal of Engineering & Scientific Research

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Page 1: WASTE HEAT RECOVERY FROM FURNAC FLUE E …nijesr.iefr.edu.pk/journalFolder/6/1f9ec.pdf · WASTE HEAT RECOVERY FROM FURNAC FLUE E GASES USING WASTE HEA RECOVERT Y BOILER ... (WHRB)

WASTE HEAT R E C O V E R Y FROM FURNACE F L U E GASES USING WASTE HEAT R E C O V E R Y B O I L E R

SyedAmjad Ahmad*, **Saqib Ehsan, ***Muhammad UsmanBabar, ***SyedHasnainHussainb, ***Hafiz Abdul-ur-Rehmanb, ***Muharnmad Qasim

*Head Mechanical Engg, * * *Students-Department of Mechanical Engineering, NFC Institute of Engineering and Fertilizer Research, Faisalabad

** Head Civil Engg. Department, NFC IE&FR, Faisalabad

Correspondence Author: samjadahmad67@yahoo. com

Abstract: Energy saving is one of the key issues, not only from the point of view of fuel consumption but also for the protection of global environment. So, it is imperative that a significant and concrete effort should be made for conserving energy through waste heat recovery. This research paper will address the problem of heat energy which is wasted away from furnace in the form of flue gases. The main object is to recover waste heat from the system and transfer the lost energy from the source back into the useful work and also to make the energy conversionprocess as efficient as possible. There are various techniques in use, for recovery of waste heat from various systems under different situation. This work is carried out on prototype Cupolafurnace whichis the most widely used industrial melting furnace. While a two pass fire tube Boiler is used as waste heat recovery boiler (WHRB). This paper involves the (a) calculation of energy which is wasted due to the different heat losses in furnace, (b) Recovery of the waste heat of flue gases, (c) Generation of process steam in WHRB. Some techniques are suggested in this work, in order to minimize the losses of waste heat energy, and also the suggestions forfurtherwork infuture.

Keywords: Waste, Cupola furnace, Heat losses, Dust catcher, Recovery boiler.

1. Introduction

Waste heat is the heat, which is generated in a process by way of fuel combustion or chemical reaction, and then "dumped" into the environment even though it could still be utilized for some useful and economic purposes. Waste heat, in most general sense, is the energy associated with the waste streams of air, gases, and liquids that leave the boundaries of a plant or building and enter into the environment. Waste heat which is rejected from a process at a temperature enough high above the ambient temperature permits the recovery of energy for some useful purposes in an economic manner. The essential quality of heat is not the amount but its "value". The strategy of how to recover this heat depends not only on the temperature of the waste heat sources but also on the economics involves behind the technology incorporated.

Reay found by experiments that not only is heat recovery economical, but that it also reduces pollution. He used heat exchangers for recovering the heat [1]. Jekerle. Jiri Ormann. and Heinrich Rothenpieler. invented a waste heat boiler in 2006 which included an axial bypass pipe and multiple heat transfer pipes disposed within a cylindrical jacket [2]. Cosme Matias Meneze(CMM) group in 2005 conducted a research on heat recovery boiler

and they concluded that the steam generated can be used as main stream steam[3].Schalles found that much of the heat produced in melting operation is lost to atmosphere. When this waste energy is re­used, i t may save up to approximately 20% of a facility's energy cost and, in some cases, reduce emissions [4]. Tang Jinquan developed many waste heat recovery power plants (WHRPP) while serving as Chief Technical Director of Dalian East New Energy Development Co., L td [5]. Denmark is probably the most active energy recycler, obtaining about 55% of its energy from CHP and waste heat recovery [6] . Tugrul Ogulata discussed the utilization of waste-heat recovery in textile drying process [7]. Soylemez studied on the thermo economical optimization o f Heat Pipe Heat Exchanger (HPHE) for waste heat recovery system [8, 9]. Lukitobudi, Akbarzadeh and Johnson found that high temperature steam which is generated by W H R B could be more conveniently used for some useful purpose [10]. Zainal Zakaria and Nor Ismail Hashim found that the cost of system increases due to the erosion and corrosion in boiler[ 11].Energy consumption by the system and environmental pollution can still further be reduced by designing and employing energy saving equipments.

NFC-IEFR Journal of Engineering & Scientific Research

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

2. Material and Methods

In this system, Cupola furnace is used for melting of iron while coke is used as a fuel having a calorific value of28000-31000 KJ/kg. Excess air required for combustion is provided by a blower. The part of air which is not used in the combustion process, takes heat form the combustion with it and escapes. This is called Flue gas heat loss. In this system this flue gas instead o f being allowed to escape in the environment is directed towards the WHRB. Here this waste heat is recovered by converting water into steam. A dust collector is installed between furnace and boiler which cleans the hot gases entering into the boiler. The Cupola furnace and the W H R B has the following specifications.

Table 1: Specifications of Cupola Furnace

Capacity 20-25kg per batch Charge Flow Rate 200-225 kg/hr Fuel Flow Rate 33Kg/hr A i r Flow Rate 28.96kg/hr Theoretical A i r Required 12-14Kg/Kg o f Coke Furnace Exhaust Temperature 850°C Charge Initial Temperature 30°C Melting Point of Iron 1482-1530°C Talent Heat ofFusion of Iron 126K.T/Kg

Table 2: Specifications of Two Pass Fire Tube Boiler

Outside Diameter o f Shell 0.406 m Inside Diameter o f Shell 0.4 m L e n g t h o f Tube 0.6 m W a l l Thickness 6 m m N u m b e r o f Smal l Tubes 15 N u m b e r o f Large Tubes 1 Tota l L e n g t h 0.6 x 16 - 9.6 m Outer Diamete r o f Sma l l Tube 0.032 m Inner Diamete r o f Smal l Tube 0.025 m Smal l Tube Thickness 3 .17mm Outer Diamete r o f Large Tube 0.15 m Inner Diameter o f Large l ube 0.14 m Large Tube Thickness 4.8 m m Over al l heat transfer coeff ic ient 2 4 0 K J / h r - m 2 - K Heat transfer area 1.181 m 2

The complete waste heat recovery system is shown in the following diagram. The detailed drawings of individual parts are given in the end of this paper.

Fig. 1: Waste Heat Recovery of Cupola Furnace Using Waste Heat Recovery Boiler

2.1 Furnace Efficiency

The efficiency of a furnace is the ratio of useful output to heatinput. The furnace efficiency can be determined by both direct and indirect method. [12]

Direct Method Testing

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 =

He an :n cbe stock _ _

•—— X 100 = 17 4 0 / Heat the fuel co^su^ned . - r / u

Heatinthe Stock = Q = mjCp^T + mjef m f: Mass of Iron = 225Kg/hr C p f: Specific Heat of Iron= 0.46 KJ/Kg-K A T : Melting Temperature of Iron(1482°C) Charge Initial Temperature(30°C) = 1452°C Xt: Latent Heat ofFusion of Iron =126 KJ/Kg

So

Heat in the Stock = Q = m f C p f AT + m f lX f= 178632 KJ/hr Heat in the Fuel Consumed = Heat Input of Solid Fuel + Heat Input of A i r =1007511.12 KJ/hr Heat Input of Solid Fuel= m c Cv= 1023 000 KJ/hr

Where,

m c : Mass of Coke = 33Kg/hr

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Cv: Calorific Value of Coke = 31,000 KJ/Kg Heat Input of A i r = m a C p a ?T = 17511.12 KJ/hr

Where,

m a : Mass of A i r = 12Kg/hr C p a: Specific Heat of A i r = 1.005 KJ/Kg-K

Indirect Method Testing

Similar to the method of evaluating boiler efficiency by indirect method, furnace efficiency can also be calculated by indirect method. Furnace efficiency is calculated after subtracting sensible heat loss in flue gas, loss due to moisture in flue gas, heat loss due to openings in furnace, heat loss through furnace skin and other unaccounted losses from the input to the furnace.

In order to find out furnace efficiency using indirect method, various parameters that are required are hourly furnace oil consumption, material output, excess air quantity, temperature of flue gas, temperature of furnace at various zones, skin temperature and hot combustion air temperature. Efficiency is determined by subtracting all the heat losses from 100.

Measurement Parameter s

The following measurements are to be made for doing the energy balance

i) Weight of stock i i ) Temperature of furnace walls, roof etc. i i i ) Flue gas temperature iv) Flue gas analysis v) Fuel consumption

Instruments l ike 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.

Sensible Heat Loss in Flue Gas:

Excess A i r = X 100 = 133% Excess A i r

Where 0 2 is the % of Oxygen in Flue Gas = 12%

Theoretical A i r Required to Burn 1 kg of Coke kg

Total A i r Supplied = Theoretical air x ( l 1 0 0

12

Total A i r Supplied = 12 x 2.3 3 kg / kg of fuel = 27.96 k g / k g of fuel SensibleHeatLoss = m g x C p g x AT m g = Weight of flue gas= Actual Mass of A i r Supplied / kg of Fuel + Mass of Fuel (1kg) = 27.96+1.0 = 28.96 k g / k g offuel Cp= Specific Heat of Flue Gas= 0.24 KCal/kg/°K = 1.0032 KJ/Kg-K AT = Temperature Difference= T f g - T a

= 850 30 = 820°K T f g: Flue Gas Temperature T a: Ambient Temperature Heat Loss = m g x Cp gx AT = = 5699.328kCal / kg of fuel =23823.19 KJ/Kg offuel

Haac Loss _

% Heat Loss in Flue gas= C v o f C o k s ~ 77%

Cv of Coke= 31000 KJ/Kg = 7150 Kcal/Kg

Loss Due to Evaporation of Moisture Present in Fuel

0.52% %Loss Where,

y.'_ = S 4 - C 4 5 ( T f g - T a ) }

Cv of Coke X 100

\l : Mass of Moisture in 1 kg of Fuel = 0.15 kg/kg of fuel

Loss Due to Evaporation of Water Formed due to Hydrogen in Fuel

%Loss=

Where,

5 N •; 5 8 4 - C- 45 ( T f z - T a ) }

Cv o f Coke

1.2% X 100 =

N : Mass H 2 i n 1 kg of Fuel = 0.04 kg/kg of Fuel

Heat Loss due to Openings:

I f a furnace body has an opening on it, the heat in the furnace escapes to the outside as radiant heat. Heat loss due to openings can be calculated by computing black body radiation at furnace temperature, and multiplying these values wi th emissivity (usually 0.8 for furnace brickwork) and the factor of radiation through openings. Factor for radiation through

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

openings can be determined with the help of Chart A -1. The black body radiation losses can be directly computed from the curves as given in the Chart A-2.

The Shape of the Opening is Square and =1.75

D: Width of Furnace Charge Opening= 0. i4m X: Furnace Wall Width= 0.077m The Factor of Radiation = 0.75 (Figure 2)

0 2 0.4 .0.6 0.8 1.0 3 4 5

RATIO • = DIAMETER OR LEAST WIDTH = D THICKNESS OF WALL X

Fig. 2: Factorsfor Determining the Equivalent of Heat Release from Openings to the Quality of Heat Release from Perfect Black Body.

Black Body Radiation Corresponding to 1482°C = 49.5KCal/cm7hr(Fig.3)

300 500 700 800 1100 1300 1500 1700 1900 Temperature (°C)

Fig. 3: Graph for Determining Black Body Radiation at a Particular Temperature

Area of Opening = 283.87 cm

NFC-IEFR Journal of Engineering & Scientific Research

Emissivity = 0.8

Total Heat Loss

= (black body radiation) x (area of opening) x (factor of radiation) x (emissivity)

= 49.5 x 283.87 x 0.75 x 0.8 = 8516.1KCal/hr

- 1 „ , , Total Heat Loss 6:161 ; 1

Equivalent Fuel loss = , , — = - r r - = 1.18 Kg/hr

% of heat loss

Cv of Coke

E q u i v a l e n t fuel Loss

7150

X 100 = 3.5% Mass Flo' .vRate o t F u e l

Heat Loss through Sidewall

Total Average Surface Temperature = 140°C= 413°K

Heat loss at 140 °C = 1450KCal / ml hr (Chart A¬3)

Total Surface Area = 2™z - i s (r, + r,) + s(tf \ i?) = 1.773 8m 2

Where,

1 : Smaller Area of Furnace Fructus =0.129 m

rz: Outer Diameter of Furnace = 0.20 m

s : Slant Height = 0.617 m

z: Length of Cylindrical Drum = 0.711 m

Total Heat Loss = (Total Area) x (Heat lossat 140 °C) = 2572 Kcal/hr

Equivalent Fuel Loss Total Heat Loss

Cv of Fuel 0.360 Kg/hr

Percentage Loss 0 3 6 0

X 100 = 1.09%

• Sensibe Heat loss

• Evaporation of moisture in fue

• Evaporation of water formed from hydrogen in fuel

• Radiation loss

• Side wall loss

• Furnace Efficiency

Fig.4 : Pie Chart Showing Furnace efficiency and Heat

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Losses

Furnace Efficiency (Indirect Method& Direct Method)

1. Sensible heat loss in flue gas = 77 % 2. Loss due to evaporation of moisture in fuel = 0.52 % 3. Loss due to evaporation of water formed from H 2

in fuel =1 .25% 4. Heat loss due to openings = 3.5% 5. Heat loss through Side wall = 1.09% Total losses = 83.36 % Furnace Efficiency = 100 83.36 = 16.64% Furnace Efficiency I n d i r e c t M e t h o d (16.64%) s Furnace

Efficiency D i r e c t M e t h o d (17.4%)

2.2 Waste Heat Recovery Calculations

Heat available at exhaust of furnace = m g x Cp gx AT = 5699.328 KCal / kg of fuel = 23 823.19 KJ/Kg of fuel AT: Furnace Exhaust Temperature Ambient Temperature

Heat Available at Boiler Exhaust

= m g x Cp gx AT = 18611.99 KJ/Kg AT: Flue Gas Temperature at Boiler Inlet - Flue Gas Temperature atBoiler Outlet

Total Heat Recovered in Boiler

= Heat available at exhaust of furnace -Heat available at boiler exhaust

= 5209.01 KJ/Kg

Percentage Heat Recovered

He at aval L ab L e at fl a e gas

3. Results and Discussions

Waste heat in flue gases is calculated to be 23 823.19kJ/Kg which is 77% of the total heat energy generated by the fuel combustion. This heat is accounted as the waste of the metal melting process. This means that about 3A of the energy is thrown away in the environment. The heat of the flue gas recovered i n the heat recovery boi le r is

5209.01kJ/Kg. It means that 21.1% of the waste flue gas energy is recovered. Process steam is generated having temperature 473 °K and pressure 344.737864 kPa. The quantity of waste heat recovered can be increased by increasing the efficiency of heat recovery boiler and furnace itself. I t can be done by installing more heat recovery devices e.g. charge pre heater, feed water pre heater, air pre heater.

Waste heat recovered in the waste heat recovery boiler is 21.1%. This amount of the heat recovered can be increased by enhancing the efficiency of the boiler and by installing more heat recovering equipments .e.g. air pre heater, charge pre heater, etc.

Material Selection:

The amount of heat recovered in this project can be increases by choosing the right material for the pipes used in boiler. The ideal material used for this purpose is copper. Copper is an excellent thermal conductor. But its machining and joining are very difficult as well as expensive. Moreover, its cost is very high. Due to these reasons, mild steel was selected. I f copper is used, the efficiency of the Heat Recovery Boiler (HRB) would increase which would result in the increased amount of recovered waste heat.

Fuel Saving:

The product is heated in a furnace or oven. This results in energy losses in different areas and forms. First, the metal structure and insulation of the furnace must be heated so their interior surfaces are about the same temperature as the product they contain. This stored heat is held in the structure until the furnace shuts down, then it leaks out into the surrounding area. The more frequently the furnace is cycled from cold to hot and back to cold again, the more frequently this stored heat must be replaced. In addition, because the furnace cannot run production until i t has reached the proper operating temperature, the process of storing heat in i t causes lost production time. Fuel is consumed with no useful output. I f the insulation of the furnace material is enhances, the convections losses w i l l reduce due to which the production time of the furnace w i l l decrease and fuel which was wasting away earlier w i l l be saved up to some extent.

NFC-IEFR Journal of Engineering & Scientific Research

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Additional heat losses take place while the furnace is in production. Wall or transmission losses are caused by the conduction of heat through the walls, roof, and floor of the heating device. Once that heat reaches the outer skin of the furnace and radiates to the surrounding area or is carried away by air currents, i t must be replaced by an equal amount taken from the combustion gases. This process continues as long as the furnace is at an elevated temperature.

Anywhere or anytime there is an opening in the furnace enclosure, heat is lost by radiation, often at a rapid rate. These openings include the furnace flues and stacks them-selves, as well as doors left partially open to accommodate oversized work in the furnace. Hot surfaces radiate energy to nearby colder surfaces, and the rate of heat transfer increases with the fourth power o f the surface's absolute temperature.

For every fuel, there is a chemically stoichiometric, amount of air required to burn it. One cubic foot of natural gas, for example, requires about 10 cubic feet of combustion air. Stoichiometric combustion w i l l produce the highest flame temperatures and thermal efficiencies, or lean (excess air). Either way, i t wastes fuel. Because there is not enough air for complete combustion, operating the burners at rich combustion conditions wastes fuel by allowing i t to be discarded with some of its energy unused. I t also generates large amounts of carbon monoxide (CO) and unburned hydrocarbons (UHCs). A t first glance, operating lean might seem to be a better proposition because all the fuel is consumed. Indeed, a lean operation produces no flammable, toxic by-products of rich combustion, but i t does waste energy. Excess air has two effects on the combustion process. First, i t lowers the flame temperature by diluting the combustion gases, in much the same way cold water added to hot produces warm water. This lowers the temperature differential between the hot combustion gases and the furnace and load, which makes heat transfer less efficient. More damaging, however, is the increased volume of gases that are exhausted from the process. The products of stoichiometric combustion and the excess are at the same temperature. The excess air becomes one more competitor for the energy demand in the process. Because this is part of the combustion process, excess air goes to the head of the line, taking its share of the heat before the furnace and its contents.

The results can be dramatic. In a process operating at 2,000°F, available heat at stoichiometric ratio is about 45% (55% goes out the stack). Al lowing just 20% excess air into the process (roughly a 12-to-l ratio for natural gas) reduces the available heat to 38%. Now, 62% of the total heat input goes out the stack, the difference being carried away by that relatively small amount of excess air. To maintain the same temperatures and production rates in the furnace, 18% more fuel mustbeburned. [13]

However, combustion systems can be operated at other ratios. Sometimes, this is done deliberately to obtain certain operating benefits, but often i t happens simply because the burner system is out of adjustment. The ratio can go either rich or lean

Excess air does not necessarily enter the furnace as part of the combustion air supply. It can also infiltrate from the surrounding room i f there is a negative pressure in the furnace. Because of the draft effect of hot furnace stacks, negative pressures are fairly common, and cold air slips past leaky door seals and other openings in the furnace. Once in the furnace, air absorbs precious heat from the combustion system and carries i t out the stack, lowering the furnace efficiency.

Ambient air contains approximately 2 1 % oxygen with nitrogen and other inert gases as balance. The total volume of exhaust gases could be reduced by increasing the oxygen content of combustion air, either by mixing in ambient air or by using 100% oxygen. Reducing exhaust gases would result in substantial fuel savings. The exact amount of energy savings depends on the percentage of oxygen in combustion air and the flue gas temperature. Higher values of oxygen and flue gas temperature offer higher fuel savings. Obviously, the fuel savings would have to be compared to the cost of oxygen to estimate actual economic benefits.

The bottom line is that to get the best possible energy efficiency from furnaces and ovens, reduce the amount of energy carried out by the exhaust and lost to heat storage, wall conduction, conveying and cooling systems and radiation. By increasing the efficiency of the furnace, the amount of fuel required for the process reduces as an ultimate aftermath.

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Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Minimize exhaust gas volumes:

The exhausting flue gas contain very hazardous gases e.g. carbon mono-oxide, carbon dioxide, sulphur oxides, nitrogen oxides, etc. These gases are dangerous for human life in many ways. They also serve as the green house gases which are the main cause of global warming. The volume of these gases entering our environment should be reduced as much as possible.

FE - Furnace Efficiency

Carbon Dioxide in Flue Gas % Volume.'Volume Dry

Improving Burner Performance

Fig. 5: Furnace Performance Graph

Avoiding overloading and optimizing heat transfer are two ways to lower waste gas flows, but there are others. The most potent way is to closely control fuel-air ratios. Operating the furnace near the optimum fuel-air ratio for the process also controls fuel consumption. The reduction in exhaust volumes w i l l be the indirect result of efficiencies applied elsewhere. It means that i f the efficiency of W H B and other installed equipments is enhanced, insulation is improved and leakages are mitigated the escape of these harmful gases can be reduced up to a considerable amount.

References

[1] Reay, David Anthony. Reay, David G 1979, Heat recovery system: A directory of equipment and techniques.

[2] Jekerle. Jiri. Ormann. Heinrich. Rothenpieler. Klaus. June 7. 2007. Waste heat boiler, Patent 7412945

[3] The Cosmec M a t i a z Me ne ze ( C M M ) Group,2005. Research conducted on Energy Recovery Systems. Panaji, Goa, India.

[4] Schalles,David G. 2002. The Next Generation Of Combustion Technology For Aluminum M e l t i n g , Bloom Engineering Company, Pittsburgh, Pennsylvania, USA

[5] Jinquan, Tang. May 2009. Waste Heat Recovery Power Generation Engineering Technical Guidance. Dalian East New Energy Development Co., Ltd. Dalian, China

[6] World Survey of Decentralized Energy May. 2006

[7] R.Tugrul Ogulata, "Utilization of waste-heat recovery in textile drying", Appliede nergy (in press) (2004).

[8] M.S. Soylemez "On the thermo economical optimization of heat pipe heat exchanger HPHE for waste heat recovery" Energy Conversion and Management, Vol . 44, (2003)2509-2517.

[9] M.S. Soylemez, "On the thermo-economical optimization of fin sizing for waste heat r e c o v e r y " E n e r g y C o n v e r s i o n and Management, Vol.44, (2003) 859-866.

[10] R. Lukitobudi, A. Akbarzadeh, P. W. Johnson, P. Hendy,"Design, construction and testing of a thermo syphon heatexchanger for medium temperature heat recovery in bakeries"Journal of Heat Recovery Systems and CHP, Volume 15, Issue 5,July 1995, Pages 481-491.

[11] Zakaria, Zainal. Hashim, Nor Ismail. 3 Jan. 2012 , Corrosion-erosion on waste heat recovery bo i le r system via b lowdown optimization, Department of Gas Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 JohorBaru, Johor, Malaysi

[12] Energy Per formance , Assessment of Furnaces, National energy conservation center (ENERCON), Pakistan

[13] Gupta, O.P. Oct. 1997. Elements of Fuel, Furnaces and Refractories, Third Edition

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Waste Heat Recover* from Furnace Flue Gases using Waste Heat Recovery Boiler

Nomenclature rrif Mass of Iron, Kg/hr m, Mass of Air, Kg/hr

Mass of Coke, Kg/lrr Weight of flue gas, kg / kg of fuel

M, Steam Mass, Kg/hr M Mass of Moisture in 1 kg of fuel, kg/kj ; of fuel N Mass H 2in 1 kg of fuel, kg/kg of fuel cP

Specific heat of flue gas, KJ/Kg-K cPf

Specific Heat of Iron, KJ/Kg-K cpa Specific Heat of Air, KJ/Kg-K c Specific Heat Of Water , KJ/Kg-K A, Latent Heat ofFusion of Iron, KJ/Kg ?T Temperature Difference. °K T f t

Flue Gas Temperature, °K T. Ambient Temperature, °K Ts

Steam Temperature °K T f

Feed Water Temperature, °K Thi

Boiler Hotter fluid Inlet Temperature , •K T

1 CO Boiler Colder fluid Outlet Temperature, °K

T 1 ho

Boiler Hotter fluid Outlet Temperature ,°K T Boiler Colder fluid Inlet Temperature , °K D Width of furnace Charge opening, m X Furnace wall width, m • i Smaller Area of Furnace Fructus, m

r 2 Outer Diameter of Furnace, m s Furnace Slant Height, m z Length of Furnace cylindrical drum, m

Enthalpy of feed water, KJ/Kg Enthalpy of saturated vapor, KJ/Kg

K Thermal Conductivity of Water, KJ / m-hr-K Cv Calorific Value of Coke. KJ/Kg o 2 Percentage of oxygen in flue gas, % P Density, Kg/m3

Project: waste heat recovery of cupola fumice

scale; 1:1 Side view

Cupola furnace

Dra wn by; Date: 23-10-12 Checked by:

Fig. 6: Furnace Side View

Project: waste heat recovery of cupola furaiice

scale: 1:1 Top view

Cupola furnace

Dra-.vn bv: .?1.32,33,53 Date: 23-10-12 Checked bv:

Fig. 7: Furnace Top View

NFC-IEFR Journal of Engineering & Scientific Research

Page 9: WASTE HEAT RECOVERY FROM FURNAC FLUE E …nijesr.iefr.edu.pk/journalFolder/6/1f9ec.pdf · WASTE HEAT RECOVERY FROM FURNAC FLUE E GASES USING WASTE HEA RECOVERT Y BOILER ... (WHRB)

Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Project: waste heat recovery of cupola fur;mce

scale: 1:1 Front view

Cupola furnace

Dra wn by: 31.32,33,33 Date: 23-10-12 Cheeked by:

Fig. 8: Furnace Front View

Project: waste heat recovery of cupola furmce

scale 1:1 Front view

Dust Catcher

Drawn bv: 3132,33,3.3 Date: 23-10-12 Cheeked by

Fig. 9: Dust Catcher Front View

NFC-IEFR Journal of Engineering & Scientific Research - <L43>

Project: waste heat recovery of cupola fur;ince

scale: 1:1 Top \iew

Dust Catcher

Dra wn by: 31,32,33,53 Date: 23-10-12 Cheeked by:

Fig. 10: Dust Catcher Top View

Project: waste heat recovery of cupola fur;uice

scale ; 1:1 Top view

Waste heat boiler

Drawn bv; 31,32,33,53 Date: 23-10-12 Checked hv:

Fig. 11: Boiler Top View

Page 10: WASTE HEAT RECOVERY FROM FURNAC FLUE E …nijesr.iefr.edu.pk/journalFolder/6/1f9ec.pdf · WASTE HEAT RECOVERY FROM FURNAC FLUE E GASES USING WASTE HEA RECOVERT Y BOILER ... (WHRB)

Waste Heat Recovery from Furnace Flue Gases using Waste Heat Recovery Boiler

Project: waste heat recovery of cupola furaiice

scale ; 1; 1 Front view

Waste heat boiler

Drawn bv: 31.32,33,53 Date: 23-10-12 Checked by:

Fig. 12: Boiler Front View

Project: waste heat recovery of cupola furance

scale : 1:1 Front view

Elbow with Butterfly valve

Drawn bv: 31,32,33,53 Date: 23-10-12 Checked bv

Fig. 13: Furnace Elbow with Butterfly Valve Front View

NFC-IEFR Journal of Engineering & Scientific Research M 44