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Patent Searching and Data


Title:
A METHOD FOR CONNECTING TWO ROWS OF SECTIONS IN A RING FURNACE AND A DEVICE IN CONNECTION WITH SUCH A METHOD
Document Type and Number:
WIPO Patent Application WO/2002/099350
Kind Code:
A1
Abstract:
The present invention concerns a method and a device for connecting firing gas passages in an outermost section in one row in a ring furnace for calcining of carbon bodies to firing gas passages in the matching outermost section in the parallel row via a connecting duct (1). The active flow cross-section in the connecting duct (1) is gradually reduced in the direction of flow of the firing gas by installing a flow director (2) inside the connecting duct (1). This results in the firing gases being distributed as evenly as possible between the firing gas passages (6, 6') in the head wall (7) and problems associated with uneven gas distribution in the first sections in the furnace rows being minimised.

Inventors:
RUUD ANDERS (NO)
HOLDEN INGE (NO)
ANDERSON NIGEL MARTIN (NO)
Application Number:
PCT/NO2002/000200
Publication Date:
December 12, 2002
Filing Date:
June 05, 2002
Export Citation:
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Assignee:
NORSK HYDRO AS (NO)
RUUD ANDERS (NO)
HOLDEN INGE (NO)
ANDERSON NIGEL MARTIN (NO)
International Classes:
F27B13/02; F27B13/06; (IPC1-7): F27B13/02; F27B13/06
Foreign References:
US4269592A1981-05-26
US4215982A1980-08-05
EP0726438A21996-08-14
Attorney, Agent or Firm:
Berg, André (Norsk Hydro ASA Oslo, NO)
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Claims:
Claims
1. A method for connecting firing gas passages in an outermost section in one row in a ring furnace for calcining of carbon bodies to firing gas passages in a matching outermost section in a parallel row via a connecting duct, characterised in that the active flow crosssection in the connecting duct (1) is gradually reduced in the direction of flow of the firing gas in order to achieve an even distribution of firing gas between the firing gas passages (6,6').
2. A method in accordance with claim 1, characterised in that the active flow crosssection is reduced by installing a flow director (2) inside the connecting duct (1).
3. A method in accordance with claim 2, characterised in that the flow director (2) may be removed and installed at the other end of the connecting duct (1) if the firing direction in the furnace is changed.
4. A device in connection with a connecting duct which connects firing gas passages in an outermost section in one row in a ring furnace for calcining of carbon bodies to firing gas passages in a matching outermost section in a parallel row, characterised in that the device consists of a flow director (2) which is designed as an inclined wall in relation to the direction of flow of the connecting duct (1).
5. A device in accordance with claim 4, characterised in that the flow director (2) is at least fixed at one end and that the fixing allows expansion/contraction of the flow director (2). A device in accordance with claim 4, characterised in that the length and angle of the flow director (2) in relation to the direction of flow in the connecting duct (1) are adapted to the specific furnace.
Description:
A Method for Connecting Two Rows of Sections in a Ring Furnace and a Device in Connection with Such a Method The present invention concerns a method for connecting firing gas passages in the outermost section in one row in a ring furnace for calcining of carbon bodies to firing gas passages in the matching outermost section in the parallel row via a connecting duct.

Moreover, the present invention concerns a device in connection with such a method, whereby a flow director is installed inside the connecting duct, which will contribute to reducing the active flow cross-section and which is also designed to minimise problems with uneven gas distribution in the first sections in the furnace rows.

In a ring furnace, two rows of sections are usually built next to each other in parallel rows. At each end of a row of sections, the gas ducts are connected to the parallel row of sections via a connecting duct. In this way, the sections are joined together to form a ring.

Such furnaces have a firing cycle which is gradually moved in relation to the sections as the carbon material is calcined. The firing gases from a section are conducted to an adjacent section in the direction of firing via passages arranged in head walls located between the sections. Each section may be divided into several smaller pits or cassettes by means of partition walls or so-called cassette walls. These walls are provided with ducts for the firing gases, and heat is supplied to the carbon material to be calcined by conducting firing gases through these ducts.

In ring furnaces, a section may be divided into two parts by a barrier wall in the space below the cassettes. The firing gases are then conducted up through one half and down through the other half in the ducts of the cassette walls in the direction of firing.

At the end of the row of sections, the firing gases are conducted from the firing gas passages via a connecting duct to the firing gas passages in the outermost section in the parallel row. One problem associated with prior art connecting ducts is that they may produce uneven gas distribution in the first sections in the furnace rows. US 4.215.982 shows a ring furnace which is used for baking carbon bodies in which the two rows of sections are connected via a transverse duct. The duct connects the firing gas passages in the outermost section in one row to the firing gas passages in the outermost section in the parallel row. Nothing is stated about the inner design of the duct.

One aim of the present invention was to arrive at a method and device for connecting firing gas passages in the outermost section in one row to firing gas passages in the outermost section in the parallel row in such a way that the problems associated with uneven gas distribution and thus undesired temperature variations are minimised.

It is desirable to have a connecting duct which is designed in such a way that the firing gases are distributed as evenly as possible between the gas passages in the head walls. This may be achieved by placing a flow director inside the connecting duct. The flow director may consist of elements as stated in the applicant's own Norwegian patent application no. NO 20012044.

A gradual reduction in the active flow cross-section of the connecting duct will lead to a considerably improved flow pattern into the first section. This will, among other things, contribute to the achievement of a more even temperature distribution in the sections, which, in turn, results in a more even calcining level (lower standard deviation) of the carbon bodies overall in the section. The effects of this are increased production and/or a reduction in the quantity of energy (oil or gas) which must be supplied to the process.

These and other advantageous features are achieved by means of the present invention as it is defined in the attached claims 1 and 4.

The present invention will be described in further detail in the following with examples and figures, where: Fig. 1 shows a plan view of the end of a ring furnace with two rows of sections connected to a connecting duct, where the section is taken just above the base of the sections.

Fig. 2 shows, in perspective from below, a part of a connecting duct with a flow director and an adjacent head wall with firing gas passages.

Figure 1 shows a plan view of the end of a ring furnace with two rows of sections. The section is taken at the lower end of the head wall and just above the base of the sections. The sections are connected to a connecting duct 1. A flow director 2 is placed in the end of the connecting duct 1, and the firing gases FG flow towards it. The firing gases FG flow from the space below the partially shown section K3 through the firing gas passages 3,3'in the head wall 4. For the sake of clarity, only two of the firing gas passages are marked with reference numbers, but there are firing gas passages along the entire head wall. The firing gases FG flow on through the connecting duct 1, and the flow director 2 ensures even distribution of the firing gases FG through the firing gas passages 6 and 6'in the head wall 7 (here too, only two of the passages are marked with reference numbers) and into the space under the partially shown section K2.

Section K2 may be connected to an extraction device (not shown) which contributes to the creation of a vacuum in section K2, which makes it possible for the firing gases to flow in this direction. As examples, sections K3 and K2 are shown here, which may correspond to two of the serially connected sections in a combustion cycle as described in the applicant's own patent, US 5,759,027. The present invention will also apply successively to the other sections in the combustion cycle as the combustion process is moved forwards in the furnace, even though this is not shown in the figure.

Figure 2 shows, in perspective from below, a part of a connecting duct 1 which is designed with an arch, in which a flow director 2 forms an inclined wall by the firing gas passages 6,6'in the head wall 7 above the base of the furnace 5. The firing gases FG flow from the firing gas passages 3,3'in the head wall 4 in the outermost section in one row (not shown), through the connecting duct 1 and in through the firing gas passages 6, 6'in the head wall 7. The flow director 2 may be fixed in the connecting duct 1 at each end in such a way that at least one end fixing allows expansion/contraction of the flow director 2.

The flow director 2 will contribute to making the flow conditions between the outermost sections, here shown as sections K3 and K2, as like the flow conditions between adjacent sections in a row as possible. The length and angle of the flow director are, therefore, adapted to the specific furnace. If the firing direction is changed, the flow director 2 may be moved to the other end of the connecting duct 1 (not shown in the figure).