TỔNG QUAN VỀ Hot stove lò sấy

HOT BLAST SOVE


I. INTRODUCTION

Evolution of hot stove
 The first heat exchanger worked at 1828 in USA with pipe type, use coal as fuel. Hot blast can only be heated up to
o
315 C

 From now on then, heat exchanger continuously was developed

 We can classify:
Continuous type :
Pipe type, plate pipe

discrete type: Hot blast stove


I. INTRODUCTION

Purpose of hot stove in blast furnace plant
 To supply hot blast to blast furnace

 High hot blast temperatures are essential as they reduce the furnace’s coke requirement substantially
 To facilitate the injection of auxiliary fuels such as pulverized coal as a replacement for expensive
metallurgical coke.

 Significant effect in terms of reducing the cost of hot metal.

I. INTRODUCTION

Hot stove’s types


I. OPERATION OF HOT STOVE

 Fuel of hot stove

 Hot stove use the blast furnace gas, coke oven gas and air to burn together.
 The hot gas with high temperature will be mix with cold air to control temperature before it go to blast furnace
 To keep the hot gas continuously supplies to blast furnace, we need at less two hot stoves


I. OPERATION OF HOT STOVE

 Operation

On- gas

On- blast


II.STRUCTURE
STRUCTURE OF DME TYPE










TWO CHAMBER
BURNER
DOME
REFRACTORY
CHECKER BRICK
CAST IRON GRID
HYDRAULIC TANK


II.STRUCTURE
TWO CHAMBER

Combustion
chamber

 Combustion chamber
Place to burn fuel
Checker chember
having checker brick
for absord, release,
store heat.



checker
chamber

II.STRUCTURE
BURNER

Burner have two hole, one for fuel
(BFG + COG), one for air

Ceramic burner make by refractory, brick grade
HA65/S65KB

Fuel and air will be mixed inside ceramic burner
and burned in top of burner(outside ceramic
burner

BFG+COG

AIR


II.STRUCTURE
DOME FOR HOT STOVE


II.STRUCTURE
REFRACTORY FOR HOT STOVE
Different temperature working area we

item

will be installed different material of

position

Refractory and checker brick

45%

4

burner

1

refractory.

Al2O3
75%

To avoid thermal shock

5

2
3

3
6

4

7
8

Hot blast outlet

Upper part

Dome

5
Upper part

2

Al2O3
95.5%
Silica
95.5%
Silica
95.5%
Silica

6
45%
Upper and middle

9
1

7
middle

8
9

Middle and bottom

bottom

Al2O3
42%
fireclay
40%
fireclay
35%


II.STRUCTURE
CHECKER BRICK



Having 5 layers of checker

SL93/GW Silicon brick

brick within checker chamber
brick material

HA45/305 High alumina
FC40/315 Fire clay
FC40/325 Fire clay
FC35/330 Fire clay
FC40/315

Different temp have different

FC35/330 FC40/325 HA45/305 SL93/GW

•


II.STRUCTURE
CAST IRON GRID



To support checker
chamber, make by
cast iron.


III.PREAHEATING EXCHANGER
HYDRAULIC SYSTEM



To support combustion
chamber. During hot

stove operation, its
always happen expansion,
oil tank will control
automatic amount of oil
to support combustion
chamber.


III.PREAHEATING EXCHANGER (HEAT RECOVERY
SYSTEM)

 Purpose of heat recovery system:
 Used for purpose of save energy by means of utilization of low calorific combustion gas (BFG) and waste
gas (for preheating the combustion gas).

 Increase combustion efficiency for hot stove.
 Help the hot blast temperature to reach approx. 1250~13000C without enrichment gas.
 Control the inlet temperature of chimney.


III.PREAHEATING EXCHANGER

III.1. The heat recovery system with heat carrier medium (using Oil)


III.1. The heat recovery system with heat carrier medium (using
Oil)



Advantages

Control the temperature of

 Preheat combustion gas and air
 Inlet chimney
Through this oil service station

 Disadvantages

 Very complicated due to the addition of oil service station (pumps, discharge tank…)
 The oil is only able to operate at temperature lower than 350 0C


III.PREAHEATING EXCHANGER
III.2. The heat recovery system without heat carrier medium


III.2. The heat recovery system without heat carrier medium

 Advantages
 Very simple when we don’t need to use the oil service station
 The hot blast temperature control is simpler by bypass valve
 Disadvantages
 Cost for piping increase.
 The inlet temperature of chimney is slightly higher than the system with heat carrier medium.


III.PREAHEATING EXCHANGER
III.3. The heat recovery and preheating system

III.3. The heat recovery and preheating system

 Advantages
 Optimize save energy by combining the heat recovery and preheating system.
 Not restricted in preheating capacity of system to the temperature limitation.
 Disadvantage
 Add more cost for installation of gas fire heat exchanger.


IV.

OPERATION MODE

The stove system can operate in two different modes:

 Cyclic mode
 Parallel mode
with N = 2, the system only can operate with cyclic mode
With N > 2, the system can operate with either cyclic mode or parallel mode


IV.OPERATION MODE
General formula

θ = θh + Δθ + θc = N x ( θc – rθc)
θc(N- N*r -1) = θh + Δθ

•

•

θ:

period blast

Δθ: HS changing time

•

θh : on gas time

•

θc : on blast time

•
•

r:

overlap factor

N: amount of HS


IV.OPERATION MODE
Cyclic mode

The cyclic mode with one stove on blast and the

remaining stove being reheated



Formula: θh+Δθ = 2θc

With r =0, N = 3


IV.OPERATION MODE
Parallel mode



The parallel mode with two stove on
blast at different temperature and
two stove be reheated.



Formula: θh+Δθ = θc
with N =4, r = 0.5)