6 Zones Annealing Car Bottom Furnace Bogie Hearth Furnace 6500×2300×2000mm Gas Fired

6500×2300×2000mm Gas fired Car Bottom Furnace

Bogie Hearth Annealing 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 car bottom furnace body steel structure is made from 12-18#

U steel and 4-14mm 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. The furnace door edge is made of 14mm heat-resistant

steel casting material in several pieces.

2.2 lining

The lining material is 1260 type 1000℃ high purity refractory fiber

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 300mm

is designed as the high temperature refractory layer.

2.3 bogie

The car bottom 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 20# U-steel and 20# I-steel. The edges of

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

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 trolley type heat treatment furnace is driven by motor reducer gear

driving mechanism. The moving speed of the bogie is 6-8m/min.

2.4 Sealing System

Sealing between the furnace door and the furnace body is through the

electric push-rod. Sealing between the bogie and the real wall is through

the spring mechanism. When the bogie moves inside the hearth, the bogie

contacts tightly with the rear wall to prevent heat loss.

Bogie side sealing method

2.5 furnace door

The bogie hearth furnace for quenching 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 bottom part

is made of 20mm RQTSi5 heat resistant casting material. The furnace door

has the feature of simple, practical, reliable and convenient maintenance.

The furnace door is fixed on the bogie.

The soft contact sealing structure is arranged between furnace door and

furnace lining. The fiber sealing block around the furnace door protrudes

out of the furnace door inner lining. The furnace door frame is equipped

with thick steel plate. When the furnace door is closed, the electric push

rod is used to compress the furnace door. In this way, the sealing fiber

block fully contact with the steel plate for sealing. When the furnace door

is opened and closed, the gap between the furnace door and the steel plate

of the furnace door frame is 100mm to ensure the stable movement of the

furnace door.

2.6 burning system

The burning system is comprised of AGS 125HB 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 bogie hearth furnace for annealing 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 stress relieving car bottom furnace has a complete fault detection, alarm,

diagnosis, and safety protection system. On the control cabinet there is an alarm lamp.

3.Main Technical Parameters