Furnace door knife edge web plate

The steel plate at the center of the furnace door blade is mainly used to resist shear and also bear some bending moments.

1.Overview

Leakage of furnace doors is one of the main pollution sources of coke ovens.Due to the large number of modern large coke oven doors and the large length of sealing required,it is not easy to maintain a good sealing state during the production process of coke ovens.Especially for old coke ovens that have been put into production,their difficulty is particularly prominent.However,the current and industry requirements for environmental protection work are becoming increasingly strict.Therefore,how to ensure the tightness of coke oven doors,especially those used in production,has become a task of furnace maintenance.

2.Current situation

The 1#coke oven of the coking equipment plant was put into operation in 1989,and the 2#coke oven was put into operation in 1993.Both coke ovens are JN60-82 type and have now entered the middle and later stages of production.Due to aging furnace age and heavy production tasks,smoke often occurs at the edges of the large furnace doors after coal loading in two coke ovens.Even after routine repairs to the furnace doors,the results are not ideal.After analysis and demonstration,workshop technicians have carried out technical transformation on the blade edge of the large furnace door web plate,effectively solving the problem of smoke from the blade edge of the furnace door.

3.Analysis of Smoke Causes

The 1#and 2#coke ovens of Yigang Coking Plant adopt self sealing knife edge furnace doors.The furnace door body is made of heat-resistant cast iron,and the furnace door and furnace frame are sealed with knife edges.When aligning the doors,the knife edges are used to tightly align the furnace frame to achieve sealing purposes.The knife edges are adjusted and positioned with a spring to prevent raw gas leakage and avoid smoking.Usually,if there is a furnace door that emits smoke after coal loading,remember the smoking area.After replacing the smoking furnace door with a new one,polish the knife edge of the furnace door flat,or adjust the spring on the web plate for the stomach smoke area to achieve sealing.However,the two rnw-82 coke ovens that have been put into operation for ten years have obvious wear on the furnace frame surface,and using this furnace door repair method cannot achieve significant results.Even for some furnace numbers that have just been repaired,there is still stomach smoke phenomenon after loading coal on the opposite door,and sometimes even the use of yellow mud sealing effect is not ideal.After careful observation,the workshop technicians found that the joint between the furnace frame and the knife edge would be hit by the knife edge when aligning the door.Due to the long production time and frequent removal of the door,a circle of grooves were ground at the joint.In this situation,if the edge of the knife does not match the ground citrus when facing the door,smoke will appear at the gap,which is the reason why conventional furnace door repair methods cannot solve or the effect is not ideal.

4.Transformation methods

After identifying the cause and analyzing it,there are several ways to handle it:first,replace the furnace frame;This method is not only costly but also complex,and is not considered a solution in increasingly strict production requirements.The second is to smooth the grooves on the furnace frame;The furnace frame is made of heat-resistant cast iron,and the sealing surfaces of the furnace door frame that come into contact with the furnace door blade are all machined surfaces.The 6m high furnace frame is dismantled and transported to the outside for mechanical processing,which is expensive and affects normal furnace discharge,so it is not adopted.The third is to transform the edge of the knife.In order to provide a good sealing effect,the original design of the edge of the knife was designed with an inclined angle on the outer side of the edge.However,after production,the edge of the knife on the furnace door frequently collided with the furnace frame,causing the furnace frame to grind out grooves,resulting in smoke emission at the door deviation.If the outer inclination angle of the original furnace door blade design is changed to the inner outward inclination angle,even if there is a slight deviation when facing the door,the modified blade can still control the ground plants within its range,solving the problem of smoking.

Installation of furnace protection iron parts:

1.To avoid frequent movement of the crane and accelerate the installation progress,a comprehensive lifting method is adopted,which involves using temporary installation tools to fix the protective plate with the furnace column,and lifting both the furnace column and the protective plate simultaneously.The fixing method is to use the holes on the protective plate to fix the furnace door frame,and connect the furnace column with the protective plate using hook bolts and pressure plates.When transporting and lifting furnace columns,special attention should be paid not to increase bending.The protective plate of the regenerator is spot welded on the furnace column and also aligned with the furnace column.

2.Pressure construction technology for furnace protection iron parts.According to the design and traditional construction,the method of tightening nuts with n-shaped temporary braces is used for pressurization.It is very difficult to achieve a gap of 3mm-5mm between the protective plate and the furnace body through manual force,and it is easy to generate uneven pressurization and loose contact,leading to smoke emission from the protective iron parts during coke oven production.To reduce workload and accelerate construction progress,n-shaped card support and jack pressure construction methods can be used for pressurization.After using a jack to pressurize,the pressurization work becomes labor-saving,while improving the installation quality of furnace protection iron parts.

3.When installing the furnace door frame,attention should be paid to aligning it with the centerline of the carbonization chamber.It is strictly prohibited for the inner edge of the furnace frame to protrude beyond the protective plate,especially after tightening the top screw,attention should be paid to inspection.Therefore,temporary support should be added to the furnace frame during installation to avoid narrowing the width of the furnace frame.Special attention should be paid to strictly prohibiting the use of tightening the hook bolts to pressurize the furnace door frame.This not only does not compress the asbestos rope tightly,but also easily damages the hook bolts of the protective plate.After the furnace frame is pressurized,when tightening the bolts,they should be fixed from the center to both sides,and the bolts should be tightened crosswise on the left and right sides to evenly stress the furnace frame and prevent deformation.

The function of the coke oven protective iron parts is to apply pressure to the furnace body to offset the stress generated by temperature changes,maintain the tightness and integrity of the coke oven masonry,and prevent cracking and deformation of the masonry.Due to the harsh working conditions of the iron parts used for protecting the coke oven,the furnace temperature alternates frequently between cold and hot during use,and the heating temperature is uneven.The coke side furnace frame and protective plate have been in a high-temperature environment for a long time,and there is a common occurrence of furnace door merging and deformation.The protective plate fractures early,cracks in the bridge pipe valve body and ascending pipe base,and short service life of the coal loading hole cover,fire observation hole cover,and temperature measurement hole cover,resulting in excessive consumption.The 3#coke oven of Laiwu Iron and Steel Group Coking Plant(referred to as Laiwu Iron and Steel Coking Plant)is a 42 hole JN43-80G type coke oven with a large protective plate structure,which is quite difficult to replace.In previous coke oven designs,cast iron HT150-200 was commonly used as the material for furnace protection iron parts.Due to its low strength,toughness,and poor thermal fatigue resistance,it directly affects the service life of furnace protection iron parts.

The coke oven installation is planned to be organized and constructed in three stages.

1.Stage:The main preparation work for installation includes technical preparation,material planning,processing of machined parts,ordering and procurement of outsourced equipment,incoming inspection and acceptance of equipment,and cooperation with civil engineering work.

2.Stage:The main content of the cold installation stage of the coke oven includes the pre embedding of the bottom spray pipe,the pre embedding of the flue bend,and the installation of the furnace body protective iron to meet the drying conditions.

3.The third stage:installation and debugging stage mainly includes the installation of each repair station,the installation of the four major vehicles and their tracks,the installation of the coke table and coke discharge equipment,the installation,debugging,and closing of the exchange transmission equipment.

Installation process of coke oven equipment:

Construction of embedded parts for coke oven:

1)The installation of fire holes,coal loading holes,temperature measuring holes,coal loading car track seats,and upper tension sleeves.The overall embedding method for fire holes,coal loading holes,and temperature measuring holes is to wrap loose asbestos ropes and apply a layer of clay cement outside.The equipment installation should meet the size requirements of the drawings,and the surrounding area should be tight.

2)Burial of coal loading truck track seat.