| The hot-blast stove is one of the most important equipment of blast furnace(BF) iron making.The structure of the hot stove has undergoing a continuous development with the aim of providing ahigher temperature of hot blast than ever before to the BF. Theories and practices have proved that higher hot-blast temperature results in lower coke rate and higher volume of coal injection.Although hot-blast temperature in some key domestic enterprises has achieved the world's advanced level,most of the Local small and medium-sized enterprises in China still have a hot-blast temperature of low level.Hot-blast temperature in those enterprises is maintained at about 1050℃,and in some enterprises even lower.To catch up with the advanced international level,our average hot-blast temperature still has to be increased by 150℃-200℃.Hansteel's 2~# BF mentioned in this thesis employs the global hot-blast stove of external combustion,of which the hot-blast temperature is in a low level.Its annual average hot-blast temperature is about 960℃,which is not good for the optimization of various technical and economic indexes,and becomes the main block of the development of the BE After collecting all the parameters of hot-blast stove of the Hansteel 2~# BF,the author presents concludes various factors which may result in the low hot-blast temperature.Then the author implements a series of technical transformations to improve the hot-blast temperature in accordance with the actual situation of Hansteel.Major measures include:1) changing the preheating combustion air singly into integral-type heat pipe;2) improving the structure of the pebble-bed;3) introducing the new type of highly effective ceramic burner;4) improving the condition of the raw material to ensure the normal operation environment of the BF;5) promoting the operation system of the hot stove and 6) strengthening the pipes and arch-roof.By adopting these measures,the temperature of the arch-roof is increased,the pebble-bed heating surface and its stability are expanded,and the working condition of combustion is promoted.Meanwhile,these measures ensure the condition for the BF to get a high hot-blast temperature.After the experiment,the hot-blast temperature of Hansteel's 2~# BF increases by 159.5℃from 961.2℃to 1120.7℃,the utilization coefficient of the BF increased by 0.147t/(m~3.d),injection rate of coal increased by 20.57kg/t,and the coke rate reduced by 95.77kg/t.All these results demonstrate that this technological transformation is successful.It greatly improves the technical indexes of Hansteel's 2# BF and brings tremendous economic benefits for the related enterprise In addition,after the technological transformation,including the use of new ceramic burner,the employment of the automatic operating system and the adoption of the piping heat-insulation protection measures etc.,the thermal efficiency of hot-blast stove is greatly improved, the BF gas is saved and the workers' labor intensity is also reduced,which provide reference and experience to the technological development of the domestic enterprises of the same type.
|
PDF Full Text Request