Heat expenditure during the sintering process

Heat expenditure during the sintering process

The thermal expenditure of the sintering process includes the physical water evaporation heat of the mixture, the combined heat of the water, the limestone and the ore, the physical heat of the sinter and other heat losses.
(1) mixture physical water evaporation heat q' 1 .

Gw—the moisture content of the mixture, kg/ton;
4.2 × 595 - the heat of vaporization of water at 100 ° C, kilojoule / kg.
(2) Crystal water decomposition heat q' 2 .
q' 2 =Q' 2-1 +Q' 2-2 kJ/ton 1) Decomposition heat of slaked lime Q' 2-1 =4.2×354G x β x :
Where 4.2×354———calcium decomposition heat, kilojoule/kg;
G x ———the amount of slaked lime, kg/ton;
β x ———The actual amount of Ca(OH) 2 in slaked lime, %.
2) Decomposition heat of aqueous minerals Q' 2-2 = G K • R w • q w :
Where G k — the mass of the mineral containing mineral, kg / ton;
R w ———Water content of water content in water, %;
q w ——— Decomposition heat per kilogram of crystal water, kilojoules per kilogram of water.
(3) Carbonate decomposition heat q' 3 .
q' 3 =Q' 3 -1+Q' 3-2 kJ/ton 1) Heat of decomposition of carbonate in the flux:
Q ' 3-1 = 4.2 × 763 (G 3 • CaO + G 4 • CaO') + 4.2 × 602 (G 3 MgO + G-4MgO') kJ / ton where 4.2 × 763, 4.2 × 602 is CaO 3 and the decomposition heat of MgCO 3 , kilojoule / kg CaO, MgO;
CaO and MgO are CaO and MgO in limestone, and %;
CaO' and MgO' are CaO and MgO in the dolomite, and %.
2) when the thermal decomposition of the ore is iron ore Ling:
Q' 3-2 =4.2×154.6G ks •m FeCO3 kJ/ton 4.2×154.6———Decomposition per kilogram of siderite (FeCO 3 ) KJ/kg FeCO 3
(4) Sintered cake physical heat q' 4 .
q' 4 =G Bl c skl t Bl +G B2 •c sk2 t B2 +...G Bn •c skn t Bn kJ/ton where G Bl ,G B2 ———the amount of cake per layer, kg/ Ton;
c sk1 ,c sk2 ———the average specific heat capacity of the sintered cake of each layer between 0 and t Bi at the average temperature t B1 , t B2 ......t B2 of each layer,
KJ/kg °C;
t B1 , t B2 ———t B1 : average temperature of the sintered cake of each layer, °C.
1) Thermal sinter plant:
q' 4 =Q' 4-1 +Q' 4-2 +Q' 4-3
Q' 4-1 = G' 1 c sk t sk kJ / ton where c sk --- the average specific heat capacity of the sinter between 0---tsk;
t sk ———the average temperature of the sintered ore;
G' 1 --- Hot sinter output (G' 1 = 1000 kg).
Q' 4-2 =G 7a c sk •t rf kJ/ton where c sk ———the average specific heat of hot returning between 0°C and t rf , kJ/kg°C;
t rf ———the average temperature of hot returning, °C;
G 7a — — hot return quantity, kg / ton;
Q' 4-3 = Other heat losses include heat dissipation and dusting from the tail crushing and screening equipment . The exhaust gas carries away heat. [next]
2) Cold sinter plant:
The physical heat of the sintered cake includes the physical heat Q' 4-2 of the hot return ore and the sinter physical heat Q' 4-1 . The latter includes the physical heat Q' 4-1-1 of cold sinter, the physical heat Q' 4-1-2 of cold returning, the physical heat Q' 4-1-3 of the bottoming material, and the physical heat taken away by the cooled exhaust gas. Q' 4-1-4 , other heat loss Q' 4-1-5 , ie cooling equipment and screening equipment, etc., the calculation is as follows:
Q' 4-1-1 = Q' 1 c sk t sk kJ/ton where Q' 1 ——— 1000 kg for cold sinter plant;
Q' 4-1-2 =G 7c C sk t LK kJ/ton where G 7c ———cold return amount, kg/ton c sk ———cold return from 0---t LK The average specific heat is kJ/kg °C.
Q' 4-1-3 =G 8 C sk t pk kJ/ton where t pk ———the average temperature of the primer (after cold screening), °C;
Q' 4-1-4 =V L1 C Lf t Ly kJ/ton where t Lf ———the average temperature of the cooled exhaust gas, °C;
Q' 4-1-5 = Cooling equipment and screening equipment.
Q' 4-1-5 = Q' 4-1 -( Q' 4-1-1 + Q' 4-1-2 + Q' 4-1-3 + Q' 4-1-4 ) KJ / Ton 3) for on-board cooled sinter Q' 4-1 =( Q' 4-1-1 + Q' 4-1-2 + Q' 4-1-3 + Q' 4-1-4 )+ Q ' 4-3 kJ/kg type Q' 4-3 ———The cooling of the on-board cooler takes away the physical heat of the exhaust gas, which is calculated by the following formula.
Q' 4-3 =V L •c k •t L kJ/ton where V L ———the total amount of exhaust gas in the cooling zone, m 3 /ton;
c k ———the average specific heat capacity of the cooling exhaust gas from 0---t L °C, kJ/m 3 °C;
t L ———The temperature of the cooled exhaust gas, °C.
(5) Physical heat brought out by the sintering waste gas q' 5 .
q' 5 =V s f c f t f kJ/ton where V s f ——— total amount of sintering exhaust gas, m 3 /ton;
c f ———The average specific heat capacity of the wet exhaust gas from 0---t f °C, which can be calculated as follows:
c f =0.01(c' CO2 •CO s 2 '+c' H2O •H 2 O s '+c' N2 •N S 2 ′+......) kJ/ m3 •°C
Wherein CO s ' 2 ', H 2 O s ', N s' 2 ——— volume content of the corresponding component in the exhaust gas, %;
C' CO2 , c' H2O , c' N2 ———the average specific heat capacity of the corresponding components in the exhaust gas from 0---t f °C, kJ/ m3 • °C
t f ———The temperature of the exhaust gas, °C.
(6) Chemical incomplete combustion heat loss q' 6 .
According to the content of combustible gas in the exhaust gas, q' 6 =V s' of (30.2CO s '+25.8H s' 2 '+85.7CH s' 4 +...)×4.2 kJ/ton CO s′ 2 , H 2 O s′ , N # s′ 2 ——— volume content of corresponding components in the exhaust gas, %;
According to the volatile matter of solid fuel and the CO content in the exhaust gas, q'6=G6(Q'dw-81.0Cfg)×4.2+Vsf(30.2COS')×4.2 kJ/ton in cfg———analysis in solid fuel Base fixed carbon content, %;
81.0 × 4.2 --- carbon with heat when anthracite, coke powder when used as 79.8 × 4.2 [next]
(7) Chemical loss of sinter residual carbon q' 7
q' 7 =4.2×79.8G' 1 C c kJ/ton C c ———Residual fixed carbon in sinter, %
(8) Main heat loss q' 8 = Q' 8-1 + Q' 8-2 + Q' 8-3 + ... kJ / ton 1) Ignition heat preservation surface heat dissipation Q' 8-1

In the formula т———calculate the heat dissipation time, according to т=ι hours;
P———Sintering machine output, t/h;
A 1 ... A n ———Ignition insulation furnace surface area, m 2 ;
q 1 ......q n ———The comprehensive heat dissipation coefficient of each heat dissipation surface is calculated by the following formula:

Where ε a ——— the blackness of each surface of the ignition holding furnace;
t Bi ———the average temperature of each heat dissipating surface of the ignition holding furnace, °C;
t k ———ambient temperature (t e );
a d =A(t Bi -t e ) 1/4 kJ/m•h •°C
A———coefficient, heat dissipation face up A=2.8, down A=1.5, vertical A=2.2,
When the wind speed W f <5 m / s, a d =4.2 × (5.3 + 3.6 w f ) kJ / m • hour • ° C
>5 m / s, a d = 4.2 × (6.47W f 0.73 ) kJ / m • hour • ° C
2) Surface heat dissipation of the sintered cake of the ignition holding furnace Q' 8-2 :

Where ε b ———the blackness of the surface of the sintered cake (measured value);
t Bi ———the average surface temperature of a certain sintered cake;
A i ——— surface area of ​​a certain sintered cake, m 2 ;
Т———Calculating time ι hours;
P———Sintering machine output, t/h.
(9) Cooling water takes away physical heat Q' 9 .
q' 9 =G WL ×c WL ×Δt w kJ/ton where G wL ———cooling water consumption of the ignition furnace, kg/ton;
Δt w ———The difference between the cooling water outlet and the inlet temperature, °C.
(10) Heat loss of the sintering trolley back lane q' 10 .
q' 10 =Q x -Q B
Q x , Q B — The physical heat of the sintering trolley at the unloading and cloth, calculated by the following formula:
Q x =G tc •c tc •t tc +G tB •c tB •t tB kJ/ton Q B =G ct •c′ tc •t′ tc +G tB •c′ tB •t′ tB kJ / t ton G tc , G tB ——— The mass of the trolley body and trolley rafts that need to pass the 1 ton sinter, kg/ton.
t tc , t tB and t′ tc , t′ tB are the temperature of the trolley body and the trolley of the trolley at the unloading and cloth, °C.
(11) Difference Δq=Σq-Σq' kJ/ton Allowable relative error is specified as ±5%, ie –Δq/Σq—×100%≤5%
(12) Total heat expenditure Σq'=q' 1 +q' 2 +q' 3 +...q' 10 +Δq kJ/ton

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