Claims:1. A tuyere cooling system for blast furnace, comprising:
a body cooling circuit (300) configured to cool a body of a tuyere (100) during operation; and
a nose cooling circuit (200) configured to cool a nose end (3) of the tuyere (100) during operation wherein the nose cooling circuit comprises a channel (8) formed along the nose end (3) and parallel to a nose end (3), wherein the channel (8) has a uniform rectangular cross section with a length side oriented towards the nose end (3), and wherein corners of the channel (8) are filleted.

2. The tuyere as claimed in claim 1, wherein the tuyere (100) is a copper casted body and has a converging shape.

3. The tuyere as claimed in claim 1, wherein the channel (8) is a hollow passageway formed during casting by forming a core using a desired pattern, and keeping a constant offset from the nose end (3) and an outside wall (1).

4. The tuyere as claimed in claim 1, wherein a length and a width of the channel (8) section is in the ratio of 1.5.

5. The tuyere as claimed in claim 1, wherein one corner closest to an outside wall (1) and the nose end (3) of the channel (8) section has a higher filleting radius than other three corners.
, Description:CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application does not claim priority from any patent application.
TECHNICAL FIELD
[002] The present disclosure in general relates to the field of blast furnace. More particularly, the present subject matter relates to tuyeres in blast furnace.
BACKGROUND
[003] Generally, blast furnace is a counter current metallurgical reactor in which hot blast provided by tuyere, placed circumferentially around the blast furnace, rises up to the top of the blast furnace and comes out in the form of different gases. Whereas granular iron bearing materials in the form agglomerate like sinter and pellet and raw iron ore with definite size of coke are charged from the top. Along with hot blast different fuels like pulverized coal, plastics, charcoal are provided through tuyere to replace coke charged from the top. Iron bearing materials get reduced to liquid iron which is being drained periodically through tap hole from the blast furnace. Reduction of iron bearing materials to liquid iron happen in presence of reducing gases like carbon monoxide which is generated while carbon reacts with carbon di oxide in higher temperature. The source of carbon dioxide is the pulverized coal.
[004] Typically, as hot blast is having a temperature over 1150oC, pulverized coal in presence of this high temperature starts combusting with oxygen present in blast and creates flame temperature over 2150oC just in front of the tuyere. Close proximity to high temperature requires that tuyeres are cooled and constructed of high thermal conductivity material like copper. With average life of tuyere being around 6 months, one of the major reasons of interruption in blast furnace operation is to replace damaged tuyere after their life is over.
SUMMARY
[005] Before the present tuyere cooling system and are described, it is to be understood that this application is not limited to a particular tuyere cooling system, as described, as there may be multiple possible embodiments, which are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular implementations, versions, or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a tuyere cooling system. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[006] In one embodiment, a tuyere cooling system comprises a body cooling circuit configured to cool a body of a tuyere during operation and a nose cooling circuit configured to cool a nose end of the tuyere during operation. In one example, the nose cooling circuit comprises a channel formed along the nose end and parallel to a nose end. Further, the channel has a uniform rectangular cross section with a length side oriented towards the nose end. Furthermore, corners of the channel are filleted.
BRIEF DESCRIPTION OF DRAWINGS
[007] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present subject matter, an example of construction of the present subject matter is provided as figures; however, the present subject matter is not limited to the specific tuyere cooling system disclosed in the document and the figures.
[008] The present subject matter is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.
[009] Figure 1 illustrates a cross section of a tuyere comprising a tuyere cooling system, in accordance with an embodiment of the present subject matter.
[0010] Figure 2 illustrates a nose cooling circuit of the tuyere cooling system, in accordance with an embodiment of the present subject matter.
[0011] Figure 3 illustrates a body cooling circuit of the tuyere cooling system, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[0012] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Further the word, “system” is intended to be open ended in that should be understood to be a synonyms to “apparatus”, “machine”, “device” or “arrangement”. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any tuyere cooling system and, similar or equivalent to those described herein may be used in the practice or testing of embodiments of the present disclosure, the exemplary, tuyere cooling system and are now described.
[0013] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments described, but is to be accorded the widest scope consist in this regard, in a generic sense.
[0014] Further to the above description, with demand of increasing steel production, sizes of the blast furnaces are increasing over the years. Furthermore, the increasing cost of coke production has forced blast furnace operator to introduce cheaper fuels through tuyeres, which typically require higher temperature to burn. This has led to an increase in the temperature around the tuyere. Hence, the life of the tuyere has decreased and the cost of replacement of tuyere has increased due to size of the blast furnaces. Thus, there exists a needs for a means to increase tuyere average life time and enable the tuyere to function properly for longer duration.
[0015] In one embodiment of the present subject, a tuyere cooling system comprises a body cooling circuit configured to cool a body of a tuyere during operation and a nose cooling circuit configured to cool a nose end of the tuyere during operation. In one example, the tuyere is a copper casted body and has a converging shape. In one other example, the nose cooling circuit comprises a channel formed along the nose end and parallel to a nose end. The channel is a hollow passageway formed during casting by forming a core using a desired pattern, and keeping a constant offset from the nose end and an outside wall. Further, the channel has a uniform rectangular cross section with a length side oriented towards the nose end. Furthermore, corners of the channel are filleted. In one example, one corner closest to an outside wall and the nose end of the channel section has a higher filleting radius than other three corners.
[0016] Referring to the figures, FIG. 1 represents a tuyere 100 comprising a tuyere cooling system. In one example, the tuyere 100 has a cast copper body having general shape of converging nozzle and a central aperture further connected to a blow pipe (not shown) through which during operation a hot blast is provided. Further, tuyere 100 consists of an outer wall 1 and inner wall 2 both made of copper joined at the nose end 3 to define the tuyere 100 shape. On the other hand, inner wall 2 and outer wall 1 joined at the rear end 4 at which there are provisions for connection for inlet and outlets for cooling circuits. The outer wall 1 and nose end 3 are exposed to very high temperature and the rear end 4 is located outside of a blast furnace shell thus exposed to very minor heat.
[0017] Referring to figure 2 and figure 3, two different cooling circuits are present in the tuyere 100 are disclose. In the embodiment in order to cool the nose end 3 more efficiently a nose cooling circuit 200 is implemented and to cool the body, a body cooling circuit 300 is implemented. Further, the nose cooling circuit 200 and the body cooling circuit 300 are separated by solid copper 5. As shown in figure 2, in the nose cooling circuit 200, a copper inlet tube 6 and a copper outlet tube 7 extend inwardly parallel to each other to exchange coolant with a channel 8 formed around the nose portion 3.
[0018] In one embodiment, the channel 8 has an inlet 10 at one end and an outlet 11 at the other end that communicate with the tubes 6 and 7 to form a smooth flow path so as to avoid any recirculation of flow which could undesirably affect the thermal performance of the tuyere.
[0019] In one example, the copper inlet tube 6 and the copper outlet tube 7, the inlet 10, the outlet 11 along with the channel 8 are hollow passageway formed during casting by forming the core using desired pattern. Channel 8 is formed by keeping a constant offset from the nose end 3 and therefore becomes parallel. Further, a constant offset is maintained from the outside wall to provide the desired shape of the channel. The channel 8 has a uniform rectangular cross section where the corners are filleted in different radius to accommodate the plant flow rate with the pressure head available. The length and width of the rectangular cross section is in the ratio of 1.5 and one corner of the rectangular cross section is having a higher filleting radius than the other three corners.
[0020] Referring to figure 3, further to enhance the cooling at the nose end, the rear chamber of the body cooling circuit is divided into two unequal passageways. The cross-section of front of the rear chamber is intentionally made smaller to get high velocity near the nose. Coolant flows through the copper tube 12 to enter into the passageway 13 to assist in nose cooling. Passageway 13 communicates with bigger chamber 14 to form a continuous flow path and finally comes out with separate outlet 15 at rear end.
[0021] In one example, the rear chamber is formed for coolant flow in the same way like the front chamber during casting by inserting desired core.
[0022] In one embodiment, during manufacturing the core is prepared by coarser sand particle from the pattern whereas the mould is prepared by finer sand particle around the core to form exterior surface of the tuyere. Use of coarser particle to form core as it is easily collapsed during solidification of copper and therefore comes off easily. A central core is prepared and positioned to form the opening for hot blast flow.
[001] Exemplary embodiments discussed above may provide certain advantages. Though not required to practical aspects of the disclosure, these advantages may include the following:
[0023] Some embodiments of the tuyere cooling system enable improving cooling efficiency.
[0024] Some embodiments of the tuyere cooling system reduce copper temperature at the vulnerable front end keeping its mechanical strength at higher value.
[0025] Some embodiments of the tuyere cooling system reduce water boiling in the said nose cooling circuit,
[0026] Some embodiments of the tuyere cooling system hinder formation of water vapor film in the wall of said nose cooling circuit,
[0027] Some embodiments of the tuyere cooling system enable uniform heat extraction.
[0028] Some embodiments of the tuyere cooling system enable lower thermal stress generation in the tuyere and reduce chance of destruction of tuyere.
[0029] Some embodiments of the tuyere cooling system achieve reduced copper temperature keeping the pumping power as same as plant operating condition,
[0030] Some embodiments of the tuyere cooling system enable saving of pumping power.
[0031] Although implementations of the tuyere cooling systems have been described in language specific to structural features and/or, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features and are disclosed as examples of implementations.