A SYSTEM FOR THE PRE-HEATING OF THE SINTER CHARGE AND THE METHOD
THEREFOR
FIELD OF INVENTION
The present invention relates to a system for pre-heating of sinter charge and the method therefor. More particularly the present Invention relates to pre-heating of sinter charge through steam injection in balling & nodulising drum, which enables faster sintering speed and increase productivity of sintering machine.
BACKGROUND ART
The invention relates to the reduction of ores, particularly but not exclusively iron ores, by the process in which the ore is mixed with a reducing agent and the mixture is heated to the reducing temperature which further enables faster sintering speed and increase productivity 4 of sintering machine. Also, it is well known that sinter is produced from finely divided iron ore, which roasted with coke and lime by incipient fusion. Usually, such iron ore sinter is produced in sintering machines.
As a preliminary to the production of pig iron in a blast furnace, either the whole or part of the iron ore fed to the furnace is prepared by a sintering process. Ores, in a suitably sized granular form, taken from different geological sources are mixed with coke, as a fuel, together with a certain amount of water and this mixture is then passed through a blast of heated air at a high temperature to be ignited to a self-sustaining combustion. The temperature of this combustion is high enough to cause localised fusion of the components of the mixture resulting in a sintered mass which is carried from the sintering process and broken down into suitable sized lumps for convenient feeding to the Wast furnace. The sintering process is carried out in order to enhance the chemical and physical state of the feed mixture preparatory to the actual blast furnace process.

The productivity of sintering machine i.e the speed of sintering depends on three basic parameters, which includes (i) volumetric airflow rate (m3/min.) (ii) heat capacity of gas and (iii) the heat capacity sinter mix involved.
The volumetric airflow rate can be increased by reduction of bed resistance by either lowering of bed height, by improving the average grain size of the sinter mix particles and suppressing the re-condensation of water vapour in the lower horizontals of the bed.
Sinter machine permeability deteriorates due to re-condensation of vapour in the lower horizontals of the sinter bed during sintering of cold sinter charge. This is mainly due to the formation of over moistened zone in this region. Pre-heating of the sinter charge in balling and nodulising drum above the dew point temperature prevents the re-condensation of water vapour in the lower horizontals of the bed and improves the permeability of the bed. It would be apparent from the above that the volumetric flow rate of air will be increased with lesser resistance of the sinter machine Further to it, when steam is added in balling drum some of the steam condenses and moistens the charge. This leads to a more uniform distribution of charge moisture and resuts in better balling of the sinter charge, which further improves the permeability of the sinter machine. Additionally, pre-heating of the sinter charge raises the heat level of the sintering process, which leads improvement in mechanical strength of the sinter and savings in coke breeze consumption.
OBJECTS OF INVENTION
This invention relates to the system of agglomeration of finely divided solid iron oxide material that is capable of being agglomerated by heat, and more particularly to an apparatus for the agglomeration and at least partial reduction of such material and to the product that may be produced by the process.
Further it is the objective of the invention to provide an apparatus for the system of preheating of sinter charge in balling and nodulising drum to suppress the re-condensation of water vapour in the lower horizontals of the sinter machine which would improve the permeability of the sinter bed and increase the volumetric air flow rate through the sinter machine thereby facilitate increasing the vertical sintering speed.

To meet up the basic objective, them is provided an apparatus for pre-heating of sinter charge comprising of a steam injection unit for the spray of steam inside the balling drum; at least one control valve and shut off valve to regulate the flow of steam inside the balling drum to suppress the re-condensation of water vapour in the lower horizontals of the sinter bed.
Another objective of the innovation is to provide a system for increasing the heat level of the sintering process whereby saving in fuels such as coke breeze can be achieved.
Yet another objective is to provide a system, which can be used in balling drum having polymer liners.
Yet another objective of the present invention is to improve the permeability of the sinter bed thereby improving the air filtration velocity and finally improving the productivity of the sinter machine
Yet another objective of the present innovation is to provide a system where technologically required quantity of steam can be used at the desired location and in turn prevent the wastage of steam.
Another exemplary object of the present invention is to provide a method for pre-heating of sinter mix in balling & noduiising drum for faster sintering comprising the steps of preheating sinter charge in balling & noduiising drum above the dew point temperature; providing the steam at the desired location in balling & noduiising drum; providing the steam in such a manner to protect the polymer liners of the balling & noduiising drum.
Another exemplary embodiment of the peresent invention, there may be a plurality of steam injection units depending upon the size of the bailing and noduiising dmm.
Another exemplary embodiment of the present invention, there may be a plurality of control valve and shut off valve to regulate the How of steam inside the bailing drum to suppress the re-condensation of water vapour.

Other objects, features, and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE:
Fig 1 illustrates a cross sectional view of the spray nozzle fitted to one end of the spray
header in accordance with the present invention;
Figure 2 illustrates a sectional view of the balling drum with spray header and nozzle in
accordance with he present invention;
Figure 3 illustrates a general arrangement of the control valve station and shut off valve in
the pipe line for the flow control and tor shutting off the steam with the stoppage of the
balling drum in accordance with the present invention.
DETAILED DESCRIPTION
Such as herein described, in the apparatus, the pre-heating of sinter charge in balling & nodulising drum is carried out by steam injection above the dew point temperature (up to 60°C). Preferably, a steam injection unit does the steam injection for pre-heating of sinter charge is carried out at select location (beyond the dry mix zone) inside the balling drum. The steam injection inside the balling drum is carned out with a row of spray headers with specially designed nozzles, fitted at one end of these headers. The above apparatus have control valves and shut off valves to inject the steam in the drum as per the requirement.
The said nozzles are specially designed so that the steam spray is over the maximum area of the sinter mix. The spray nozzle has three tapered holes. The distance of these spray nozzles from the sinter mix is around 100-150mm. The figure 1 shows the three tapered holes. Two tapered holes have spray angle of 60° and the central hole has 90° spray angle. The total diameter of the nozzle is 105mm and the height of the nozzle is 90mm. The distance between the two centers of the slant holes is 70mm. The top of the tapered hole is of 10mm diameter and bottom is of 25mm diameter. These nozzles are made from SS316.

The Figure 2 shows the sectional view of the bailing drum with spray header and nozzle. The figure also shows the profile of the sinter mix material when me drum is rotating and the distance of the spray nozzle from the sinter mix inside the balling drum. The spray headers are seamless pipes of 32NB. At the lop the spray header is flanged connected to 100NB steam header.
The angle of the said spray header is kept at 42° from the vertical so that the spray of the steam is over the sinter mix and not on the polymer liners of the balling drum. Further the apparatus is configured to control the flow of steam as per technological requirement through a set of control and shut of valves.
A general arrangement of the control valve station and shut off valve in the pipe line for the flow control and for shutting off the steam with the stoppage of the balling drum is shown in Figure 3. The pressure reducing control valve station sets the pressure at which the steam is to be injected in the balling drum. The quantity of steam required is around 12kg of steam per tonne of sinter charge in balling drum to raise its temperature to 60°C from 33 - 35°C. The electro-pneumatic shut off valve ensures the immediate stoppage of steam inside the drum when drum stops rotating. The logic in the PLC has been made so that the steam spray starts after two minutes when the balling drum starts rotating. This timing also ensures that the steam spray is over the sinter mix only and not on the polymer liner of the drum.
It is thus possible by way of the disclosed apparatus for steam injection in balling & nodulising drum to pre-heat the sinter mix up to 60oPC. The suppression of re-condensation of water vapour in the lower horizontals of the sinter bed has led to increase in the permeability of the bed. The improvement in the permeability of the bed is reflected in the increase in air filtration velocity through the sinter bed from 0.33m/s to 0.39m/s. The increase in the volumetric flow of air through the sinter bed results in improvement in vertical sintering speed and hence an increase in sintering machine speeds. Trials conducted in the sinter plant shows an improvement in performanc© parameters of the sinter plant like sinter machine speed from 2.12m/min to 225nVmin , reduction in in-plant return fines (-5mm) from 471 to 417kg /1, Blast furnace return fines from 182kg /1 to 170kg /1 of sinter production and reduction in coke breeze addition toy 0.5tfnr. The overall productivity of sinter machine has increased from 1.24 to 1.29t/m2/hr.

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

We Claim:
1. An apparatus for pre-heating of sinter charge comprising of:
a steam injection unit for the spray of steam inside the balling drum; at least one control valve and shut off valve to regulate the flow of steam inside the balling drum to pre-heat the sinter charge & suppress the re-condensation of water vapour in the lower horizontals of the sinter bed.
2. An apparatus for pre-heating of sinter charge as claimed in claim 1, wherein the
steam injection unit further comprises of a row of spray headers with specially
designed nozzles, having desired angles and tapered holes to cover wide area for
steam spray over the sinter charge fitted at one end of the said headers.
3. An apparatus for pre-heating of sinter charge as claimed in claim 1, wherein the
nozzles comprises of a plurality of tapered holes having spray angle of 60° and also a
plurality of central holes which have 90° spray angle.
4. An apparatus for pre-heating of sinter charge as claimed in claim 1, wherein the
angle of the said spray nozzle is kept at 42° from the vertical so that the spray of the
steam is over the sinter mix and not on the polymer liners of the balling drum.
5. An apparatus for pre-heating of sinter charge as claimed in claim 1, wherein the
steam injection in balling & nodulising drum pre-heats the sinter mix up to 60°C for
the suppression of re-condensation of water vapour in the lower horizontals of the
sinter bed.
6. An apparatus for pre-heating of sinter charge as claimed in claim 1, wherein the
distance of these spray nozzles from the sinter mix is around 100-150mm.
7. An apparatus for pre-heating of sinter charge as claimed in any of the preceding
claims wherein steam injection aver the sinter charge is controlled through a set
manual and control valves.

8. An apparatus for pre-heating of sinter charge as claimed in any of the preceding
claims wherein process intensification is achieved through steam injection such that
there is an improvement in air filtration velocity from 0.33m/s to 0.39m/s, reduction in
coke breeze consumption by 0 5t/hr, decrease in in-plant return fines from 471 to
417kg /1 of sinter production.
9. A method for preheating of sinter mix in balling & nodulising drum for faster sintering
comprising the steps of:
pre-heating sinter charge in lalling & nodulising drum above the dew point temperature;
providing the steam at the desired location in balling & nodulising drum ; and
providing the steam in such a manner to protect the polymer liners of the balling & nodulising drum.
To,
The Controller of Patents,
The Patent Office, Kolkata.
10. An apparatus for pre-heating of sinter charge, substantially as herein described with
particular reference to accompanying drawings.

The present invention relates to an apparatus for pre-heating of sinter charge comprising of a steam injection unit for the spray of steam inside the bailing drum: at least one control valve and shut off valve to regulate the flow of steam inside the balling drum to pre-heat the sinter charge & suppress the re-condensation of water vapour in the lower horizontals of the sinter bed and a method for pre-heating of sinter mix in balling & nodulising drum for faster sintering.