4500×1500×1200mm Gas fired Bogie Hearth Furnace
1. Application
The gas fired bogie hearth furnace is mainly used for heat
treatment of
metal parts
2.Structural Introduction
2.1 furnace body
The bogie hearth furnace body steel structure is made from 8# -12#U
steel and
steel plates. The side pillar and back pillars are made from
sectional steel,
and are reinforced with sectional steel bracings. The external wall
of the
furnace is painted with 2 layers of primers, and 2 layers of
coating paint.
The key part of the furnace is painted with heat resistant paint.
2.2 lining
The lining material is 1200℃ high aluminum refractory fibre
compacted block.
This refractory lining structure has the advantages of low heat
conductivity,
strong anti-shock capacity, and anti-erosion. Aluminum silicate
fiber compression
block with thickness of 350mm is designed as the high temperature
refractory layer.
2.3 bogie
The bogie hearth furnace manufacturer is comprised of heat
preservation
material, bogie frame and moving mechanism. The refractory layer is
divided
into 3 sub-layers, i.e., 1st top high-alumina brick layer, and 2nd
and 3rd layer
with both light clay bricks.
The bogie framework is made of 16# U-steel and 16# I-steel. The
edges of
the bogie are made of 20mm I-steel. The bogie is equipped with
6pieces of
wheels. Each wheel diameter is 300mm.
The heat preservation material is divided into 3 layers, the top
layer being
high-alumina bricks, and 2nd and 3rd layer being both light clay
bricks.
The bogie hearth furnace supplier is driven by motor reducer gear
driving
mechanism. The moving speed of the bogie is 6-8m/min.
2.4 Sealing System
The sealing between the door and the body of the furnace and the
trolley is
more critical.
2.5 furnace door
The car bottom furnace price door is comprised of all-fiber lining
and steel
structure shell. The door is built with silicate aluminum
compressed fiber blocks
same as that for the furnace body. The shell is a welding structure
from sectional
steel and steel plates. The furnace door has the feature of simple,
practical,
reliable and convenient maintenance. The furnace door is fixed on
the bogie.
2.6 burning system
The burning system is comprised of Krom high speed burners,
proportional
combustion control system, gas valve, solenoid valve, burner
control box, etc.
The burner has the functions of automatic ignition, flame
detection, and flame
out alarm. The burner controller receives the control signal of the
temperature
controller and controls the large/small fire status of the burner
based on the
heat load requirement so that adjustment of the temperature is
realized.
A) The burner has adjustment function and the adjustment rate is
1:10 and the
air efficient is 1-5. The burner could meet the temperature
uniformity of the heat
treatment process and effectively control the air-gas ratio so that
the fuel
consumption is reduced.
B) When the furnace is working, the burning system could
automatically cut off
the electrical gas valve and general safety valve in the case of
power failure
detected by the alarm system. When the power supply is resumed, the
worker
needs to open the safety valve and restart the ignition program
after purging
function is confirmed.
The burner is set with a proportional control unit which enables
alternative burning
of large and small fire, fire out alarm, and re-ignition. The
burner control box has
both manual and self-run modes available. The worker could operate
in front of
the furnace or in the control cabinet.
C) The pipe before the burner is equipped with solenoid valve, and
manual gas
adjustment valve. The valve system could realize an ideal gas/air
supply ratio
so that the air excess efficient is lower than 1.1.
2.6.1 air system
The air piping system is comprised of high pressure centrifugal
fan, automatic
regulation valve, pressure gauge and pipes. The air volume is to
match the
gas volume, and the air excess rate is lower than 1.20.
2.6.2 gas supply system
The general gas supply pipe is equipped with a pressure regulation
device
(equipped with a filter), a low pressure switch and a pressure
gauge. For
the sake of safety there is one fast cut-off valve on the general
gas pipe.
2.6.3 discharge system
The gas bogie hearth furnace takes direct fume discharge method.
The fume
is directly vented out through the flue pipe to the atmosphere. The
fume
conducts heat exchange with the heat exchange before emission to
the
atmosphere.
2.6.4 Furnace pressure control system
The pressure on the working table in the furnace is kept at (+15
Pa), which is
very beneficial to the uniformity of temperature and the thermal
efficiency of
the furnace. When the pressure in the furnace is too high, the hot
air in the
furnace will escape from the furnace mouth and other unsealed
places, resulting
in the heat loss caused by the escape of the flue gas; because the
high
temperature flue gas in the furnace escapes to the outside of the
furnace, it will
affect the door, the side seal and burner of the furnace directly,
which is related
to the overall service life of the furnace; when the pressure in
the furnace is too
low, a large number of cold air outside the furnace will be
absorbed into the furnace,
as well. The heat loss of off-furnace flue gas is increased. The
low pressure of the
furnace causes the diffusion of cold air outside the furnace into
the furnace, and
secondary combustion is formed due to the entry of
oxygen-containing cold air,
which has adverse effects on the uniformity of furnace temperature,
oxidation of
workpiece and thermal efficiency of the furnace. Therefore,
effective technical
measures must be taken to control the furnace pressure with full
automatic control.
Our method is to control the furnace pressure effectively by using
a system consisting
of pressure taking device, pressure transmitter, intelligent
instrument and so on. The
furnace pressure is controlled in the optimum state (the surface of
the trolley is in a
slightly positive pressure). At this time, the exhaust gas is in a
dynamic equilibrium
state, which can not only ensure that the furnace gas does not
overflow, but also ensure
that the cold air outside the furnace is not sucked into the
furnace, so as to save
energy and maximize the efficiency of the furnace.
2.6.5 Heat exchange and flue system
A flue is set at the back of the furnace, and it is carried out
with the heat exchanger
(according to the national standard GB3486-83). The flue leads to
the outside of the
factory building. The cold air is exchanged with the heat exchanger
to preheat the
combustion-supporting air before entering the burner, so as to
improve the heat
efficiency of the furnace.
Heat exchangers and flue gas exhaust pipes are insulated by
internal insulation
(using fiber castables) to ensure the service life of heat
exchangers and flues.
2.6.6 fault detection and alarm system
The fast quenching heat treatment furnace has a complete fault
detection, alarm,
diagnosis, and safety protection system. On the control cabinet
there is an alarm lamp.
2.7 control system
control system has the following parts: Ⅰ. Burning control system;
Ⅱ. Electrical
power control system; Ⅲ.temperature control system .
Measures taken for burning control system:
K type thermal couple gets mV signal and sends it to temperature
PID controller
(SHIMADEN brand). The temperature controller calculates the signal
and outputs
4-20mADC control signal to the electrical actuator. The actuator
further sends a
signal to the burner controller after calculation.
The burner controller is mainly responsible for ignition and flame
detection. When
the terminal receives the ignition signal, the burner controller
carries out flame
simulation and self testing stage. If during this simulation and
self-test stage the
burner couldn’t detect the flame signal. The burner controller
would open the
gas solenoid valve and convert the voltage 220VAC to 5KV for
ignition (ignition
time about 3S). If the burner detects the flame signal in the safe
time period
(about 8S), the yellow indication light of the burner would be on
(ignition successful).
If the burner couldn’t detect the flame signal, the red light would
be on (ignition failed).
The burner controller is locked and the gas solenoid valve is cut
off.
B) electrical power control system: The electrical power control
system mainly
controls ON/OFF of the fan, and IN/OUT of the bogie.
C) temperature control and record system
The system has the functions of temperature setup, control and
digital display.
And also there is an audible and visual alarm at over-temperature
situations.
Temperature control zone arrangement
A:temperature control system
The furnace is equipped with 2 thermal couple and an intelligent
temperature
controller. The furnace is controlled by 2 zones.
B: instrument temperature control
The temperature controller allows setup of heating time, holding
time, and cooling
time. It has self-tuning and self-adjustment function, and displays
SV and PV.
3. Main Technical Parameters
| No. | Item | Technical Parameters |
| 1 | Fuel | Natural gas |
| 2 | fuel gases calorific value Gas pressure before furnace | 8500kcal/m3 0.05-0.1Mpa |
| 3 | Rated temperature | 1200℃ |
| 4 | Normal used temperature | 500-1150℃ |
| 5 | Furnace body surface temperature | ≤45℃+room temperature |
| 6 | Max temperature rise speed | 0-150℃/h |
| 7 | Heating zone | 2 zones |
| 8 | Temperature measurement accuracy | ≤±1℃ |
| 9 | Full power gas consumption | 30m3/h |
| 10 | Gas pipe line demand | 92m3/h |
| 11 | Air consumption | 1196m3/h |
| 12 | Temperature uniformity | ≤±10℃ |
| 13 | Effective working size | 4500*1500*1200mm |
| 14 | Furnace hearth size | 4900*1900*1800mm |
| 15 | bogie max loading capacity | 5000kg |
| 16 | Quantity and model of burner | 4pcs, AGS 100HB, 230kw/h |
| 17 | Temperature control method | Intelligence temperature controller, 10 inch touch screen, Siemens
PLC and manual control; remote control of furnace door lifting and
bogie moving. |
| 18 | Temperature record | K type thermal couple |
| 19 | Furnace lining | heat resistant all fiber structure |
| 20 | Power supply | 380V, 3phase, 50Hz |
| 21 | Furnace door opening method | By electric hoist, Speed 6-8m/min |
| 22 | Bogie motor power | 5.5KW |
| 23 | Consumption index | Heat efficiency at full load η≥40% |
| 24 | Furnace door surface temperature | ≤55℃+room temperature |
