FI69923B - VAERMEVAEXLARE FOER OEVERFOERING AV VAERME TILL CELLULOSAAVFALLSLUT SOM SKALL AVDUNSTAS - Google Patents

Description

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(51) Kv.lk. * / Lnt.CI. * F 28 D 7/00 FINLAND - FINLAND (21) Application for a patent - Patentansökning 80 1 7 * »2 (22) Application date - Ansökningsdag 29.0 5.8 0 (23) Starting date - Giltighetsdag 29 05 80 (41) Made public - Blivit offentlig ^

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Patent * och regl5terstyrelsen '1 Ansökan utlagd och utl.skriften publicerad} \ \ Δ .o? (32) (33) (31) Privilege claimed — Begärd priority (70 Enso-Gutzeit Osakeyhtiö, Kanavaranta 1, 00160 Helsinki. Suomi-F in land (FI) (72) Holger Engdahl, Savonlinna, Suomi-Finland (FI) ( The present invention relates to a heat exchanger for transferring heat to a evaporative screen steam spaces arranged nested so that steam flows from the bottom up in the first outer steam space and from top to bottom in the second inner steam space, between which there is a vertical cylinder separating the steam spaces, through which openings are formed in the upper part of the jacket from the outer space to the inner one, and which heat exchanger further comprises a stop direct heat transfer pipes passing through the steam compartments, in which the liquor flows from the bottom upwards, and the necessary flow connections for supplying steam to the steam compartments.

69923

The heat exchanger 1 according to the above definition is disclosed in FI publication 62185, which is earlier than the present invention with respect to the filing date of the patent application. In the invention of the present invention, the however, the heat exchanger was not known.

Prior to the invention, it has been known to treat waste liquor from cellulose digestion with equipment comprising several heat exchangers connected in series. In this case, each heat exchanger acts as an evaporator, in which heat from hot steam is introduced into the lye. Prior to passing the liquor to the heat exchangers, it can be pretreated by allowing it to swell, whereby the generated expansion vapors are available for heating the lye. Likewise, the steam separated from the lye in each heat exchanger can be used to heat the lye in the next heat exchanger. The pulp slurry containing about 15% dry matter can be evaporated with such equipment to a dry matter content of 65%, and by utilizing the evaporation and expansion vapors separated from the liquor, the volatile components contained therein are recovered from the condensates formed in the heat exchangers.

The object of the present invention is to provide a heat exchanger suitable for the evaporation of sludge waste and, in addition, for the evaporation of the vapors separated from the liquor, in which the steam flow is more controlled than in the corresponding known solutions and is even simpler in structure. The features of the invention are set out in the claims.

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The invention will now be described in detail by way of example with reference to the accompanying drawing, in which

Fig. 1 shows a section of a heat exchanger according to the invention, and

Fig. 2 shows a section II-II of Fig. 1.

The drawing shows a heat exchanger for evaporating the waste liquor from cellulose cooking, which at the same time condenses the steam separated from the liquor at an earlier stage.

The heat exchanger comprises two vertical, nested cylinders li 1, 2 delimiting an annular outer steam space 3 of cross-section 69923 and an inner steam space 4 of circular cross-section. formed openings 5 through which steam moves from the outer space to the inner space. The steam is introduced via line 6 to the lower part of the outer steam space 3 and the non-condensable steam passing through the steam spaces exits the lower part of the inner steam space 4 to line 7. Condensates formed in the outer steam space 3 9. The waste liquor to be evaporated is introduced along line 10 to the lower end of the heat exchanger, from where it passes to vertical heat transfer tubes 11 passing through steam spaces 3 and 4. Steam evaporated from the liquor in tubes 11 escapes from the top of the heat exchanger to line 12 and evaporates.

The heat exchanger according to the drawing can be used as part of a larger process comprising several successive evaporation steps. The heat exchanger is then preceded by either another similar heat exchanger or a device in which the waste liquor from the digester is allowed to expand, and the evaporation or expansion steam obtained therefrom is used at least as part of the steam supplied to the heat exchanger via line 6. The steam then contains methanol or similar volatile components from the tail, which condense in the heat exchanger and enter the condensate. Correspondingly, the heat exchanger may be followed in the process by a similar% heat exchanger, in which the concept of lye removed via line 13 and in which the steam used to heat the lye is formed at least in part by evaporation vapor removed via line 12.

It will be clear to a person skilled in the art that the various embodiments of the invention are not limited to the example shown but may vary within the scope of the appended claims.

Claims (2)

4 PATENT CLAIMS 699 2 3 A heat exchanger for transferring heat to evaporable cellulosic waste liquor from steam consisting in part of evaporation or expansion steam separated from the liquor, the heat exchanger comprising two steam spaces (3,4] arranged one after the other so that steam flows in the first, outer steam 3 upwards and in a second, inner steam space (4) from top to bottom, between which there is a vertical cylinder (2) separating the steam spaces, with openings (5) formed in the upper part of the jacket through which steam passes from the outer space to the inner space, and comprising a heat exchanger in addition, vertical heat transfer pipes (11) passing through the steam compartments, in which the liquor flows from the bottom upwards, and the necessary flow connections (6-10, 12-13) for supplying steam to the steam compartments, condensing the steam and removing condensed steam, removing condensed steam, as well as steam evaporated from the lye and heated through loose tubes In order to remove escaped, non-evaporated lye, the heat exchanger is provided with an evaporative liquor supply line (10) which communicates via the lower end of the heat exchanger with heat transfer pipes (11) passing through both the outer and inner steam compartments (3,4). Heat exchanger according to Claim 1, characterized in that the heat transfer tubes (11) passing through both the outer and inner steam compartments (3, 4) are connected to a common non-volatile liquor outlet line (13) via the upper end of the heat exchanger.