4 Zones Bogie Hearth Heat Treatment Furnace 8000×3500×2300mm Gas Fired

8000×3500×2300mm 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 12# -18#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 bogie hearth furnace manufacturer lining adopts 1360 high aluminum refractory

fiber folding block with long-term service temperature of 1100℃. The total thickness

of furnace lining is 320mm. 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 300mm is designed as the high temperature

refractory layer.

2.3 bogie

The bogie hearth furnace price 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 20# U-steel and 20# I-steel. The edges of the bogie

are made of 20mm I-steel. The bogie is equipped with 10pieces of wheels. Each wheel

diameter is 350mm.

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 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.

The sealing between the furnace door and the furnace body uses the electric push rod.

This makes the whole door tightly sealed up, so as to ensure that the heat inside the furnace

does not leak from the door

2.5 furnace door

The bogie hearth furnace design 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.

Soft hard contact sealing structure is set between the furnace door and the furnace lining.

When the furnace door is closed, the electric push rod mechanism is used to compress the

furnace door to make the sealing fiber block contact with the furnace mouth. When the

furnace door is opened, pull the electric push rod pressing mechanism to separate the furnace

door from the furnace mouth frame steel plate with a clearance of 100 mm, so as to ensure

that the furnace door does not scratch or touch with the furnace lining and trolley during the

lifting process. And ensure smooth movement when opening and closing.

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 car bottom furnace supplier 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

old 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 wholesale car bottm 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 4 thermal couple and an intelligent temperature controller. The furnace

is controlled by 4 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