JPH0118292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat recovery roll that recovers heat using the heat of condensation of an evaporative liquid sealed in a hollow roll under reduced pressure.

In recent years, waste heat recovery has been carried out from the viewpoint of energy conservation, but conventionally, the main recovery method has been heat recovery from exhaust gas. For this reason, various devices for recovering heat from exhaust gas have been developed, but there is no device that can easily and efficiently recover the waste heat taken out from a high-temperature metal strip, such as a metal strip immediately after continuous annealing. The waste heat taken out is usually recovered by recovering cooling water.

For example, in the case of continuous annealing of stainless steel strips, the steel strip is quenched by spraying cooling water to a predetermined temperature after leaving the annealing furnace (catenary furnace), but the waste heat is recovered. This is done by using cooling water that has become hot water after cooling. Therefore, if hot water from which waste heat is recovered can be used as is, waste heat recovery is easy and efficient. However, the hot water cannot be used as is because it contains scales, sludge, etc. that have fallen off the steel strip. Therefore, in order to obtain clean hot water, it was necessary to exchange heat with cold water using a heat exchanger.

However, although the amount of hot water obtained by cooling the steel strip is large, the temperature is low, so the thermal efficiency during heat exchange is poor, and the foreign matter contained may clog the tube of the heat exchanger, making heat exchange impossible. However, there was a problem in that maintenance and management required a lot of effort.

The present invention provides a heat recovery roll that can efficiently recover heat directly from a metal strip or the like without relying on such heat recovery using cooling water.

In the heat recovery roll of the present invention, an evaporative liquid is sealed inside a hollow roll with a porous material attached to the inner periphery, and the liquid is evaporated under reduced pressure using waste heat taken out from a metal band, etc., and the resulting vapor is vaporized. The purpose is to recover the waste heat taken out of metal strips, etc. by condensing it on the surface of heat exchange pipes.

The present invention will be explained below with reference to Examples. Figure 1,
FIG. 2 shows a first embodiment of the present invention, in which FIG. 1 is a longitudinal cross-sectional view and FIG. 2 is a cross-sectional view taken at - in FIG. 1. In the figure, 1 is a hollow roll made of a material with good thermal conductivity, and a porous material 11 containing water (for example, asbestos, glass wool, etc.) is pasted on the entire inner surface. A hollow shaft 4 having a hollow hole 3 which is partially closed and partitioned inside the hollow roll 1 by partition plates 2 and 2a is hermetically fixed to the hollow roll 1. Partition plates 2, 2a
is located inside the hollow roll 1, and there are through holes 5, 5 between the part of the hollow shaft 4 where the partition plates 2, 2a are located and the part fixed to the hollow roll 1.
a is formed. Both ends of a heat exchange pipe 6 arranged spirally around the hollow shaft 4 are fixed to the portion of the hollow shaft 4 where the through holes 5, 5a are formed, and the inlet 7 of the hollow shaft 4 is connected to the inlet 7 of the hollow shaft 4. The heat recovery fluid entering from the heat exchanger pipe 6 flows out from the outlet 8 through the heat exchange pipe 6.

Further, the inside of the hollow roll 1 is reduced in pressure to below atmospheric pressure and is filled with a liquid 9. Water is usually used as the liquid 9, but other liquids can also be used depending on the heat recovery temperature. Examples include methyl alcohol, ethyl alcohol, carbon tetrachloride, and cyclohexane.

The liquid 9 is sealed in such an amount that the liquid surface does not come into contact with the heat exchange pipe 6 when the hollow roll 1 is horizontal, so that the evaporated liquid is condensed on the heat exchange pipe 6.

As described above, the heat recovery roll of the present invention has a kind of heat pipe structure, so in order to use it, the hollow roll 1 is brought into contact with the high-temperature metal band 10, and the heat is transferred from the inlet 7 of the hollow shaft 4. Supply recovery fluid. Then, since the pressure inside the hollow roll 1 is reduced, the enclosed liquid is easily boiled into steam by the heat transmitted from the metal band 10 to the hollow roll 1 and the hydrous porous body 11. However, since the heat exchange pipe 6 through which the heat recovery fluid passes is located in the steam part of the hollow roll 1, the steam that comes into contact with the surface of the heat exchange pipe 6 is easily condensed into liquid. It becomes a drop. Therefore, the heat recovery fluid entering from the inlet 7 of the hollow shaft 4 exchanges heat with the condensation heat of the steam while passing through the heat exchange pipe 6, and is heated up before reaching the outlet 8.

In addition, since a water-containing porous object 11 is attached to the inner surface of the hollow roll 1, the liquid 9 can be
The vapor evaporates from the entire inner surface of the hollow roll 1, increasing the vapor pressure inside the roll. If the water-containing porous object 11 is not pasted, the hollow roll 1 will dry in a short time when the liquid 9 in the lower part passes through the part, and the liquid 9 cannot be evaporated in the upper part, but if the water-containing porous object 11 When the object 11 is attached, the liquid 9
is always in there, so it evaporates from the entire roll. Therefore, the amount of condensation in the heat exchange pipe 6 also increases, and the heat recovery efficiency also increases.

FIG. 3 shows a second embodiment of the present invention, in which there are a plurality of flow paths for the heat recovery fluid, and
Each channel is made independent so that different fluids can flow through these channels.

That is, a plurality of hollow holes 3 facing in the axial direction are formed at both ends of the hollow shaft 4, and the end faces thereof are closed with plugs 12, thereby forming supply holes 13 and discharge holes 14 that reach each hollow hole 3 from the shaft surface. , a rotary joint 15 is fitted into a portion of the hollow shaft 4 where the supply hole 13 and the discharge hole 14 are formed, and through holes 5, 5a reaching the hollow hole 3 are formed in a portion of the hollow shaft 4 inside the hollow roll 1. to form the
These through holes 5, 5a are connected by separate heat exchange pipes 6, 6a, 6b to make each flow path independent.

Therefore, in the case of this embodiment, since the heat recovery fluid flow paths are independent, different types of fluids such as water and oil can be flowed through each flow path.

FIG. 4 shows a third embodiment of the present invention, in which heat recovery fluids of the same temperature can be supplied to obtain fluids of different temperatures. . In other words, in this example, the third
Hollow hole 3 on the heat recovery fluid supply side in the embodiment of
and supply holes 13 are combined into a single unit, and a plurality of heat exchange pipes 6, 6a,
6b are made to have different diameters, and the amount of heat exchanged by each heat exchange pipe 6, 6a, 6b is made different.

As is clear from any of the above examples,
In the heat recovery roll of the present invention, the metal band serving as a heat source and the heat recovery fluid do not come into direct contact, so the fluid after heat recovery is clean.

In addition, since the inside of the hollow roll is under reduced pressure, the liquid sealed inside easily evaporates even if the heat source temperature is low, so the heat recovery temperature range is wide, and heat recovery is performed using the condensation heat of the liquid. Therefore, it is very efficient.

For example, when water is used as the heat recovery fluid, the amount of heat recovered in the case of the present invention and in the conventional case are compared as follows. The heat source used is a continuously annealed stainless steel strip.

(1) Conventional case (cooling water spray) Cooling water spray amount 200m ³ /hr Cooling water temperature 20℃ Hot water temperature 40℃ Recovered heat amount 200 (40−20) = 400×10 ⁴ kcal/hr (2) In the present invention In this case, amount of water for heat recovery 20m ³ /hr Temperature of water for heat recovery 20℃ Temperature of hot water after heat recovery 80℃ Amount of recovered heat 20 (80-20) = 120×10 ⁴ kcal/hr Converting this to saturated steam of 6Kg/cm ² 120×10 ⁴ /650=1846Kg.

Furthermore, since the inside of the hollow roll is under reduced pressure, there is little dissolved oxygen in the liquid sealed inside the hollow roll, so that internal corrosion of the hollow roll is prevented.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a longitudinal cross-sectional view, and FIG. 2 is a cross-sectional view of FIG.
FIG. FIG. 3 is a cross-sectional view of a second embodiment of the present invention, and FIG. 4 is a longitudinal cross-sectional view of a third embodiment of the present invention. 1... Hollow roll, 2, 2a... Partition plate, 3...
...Hollow hole, 4...Hollow shaft, 5, 5a...Through hole, 6, 6a, 6b...Pipe for heat exchange, 7...
... Inlet, 8 ... Outlet, 9 ... Liquid, 10 ... Metal band, 11 ... Water-containing porous object, 12 ... Stopper,
13... Supply hole, 14... Discharge hole, 15... Rotating joint.

Claims (1)

[Scope of Claims] 1. A hollow roll with a water-containing porous substance pasted on the inner periphery, and a hollow space that penetrates both sides of the hollow roll and is partitioned by partially closing the hollow holes within the hollow roll. A shaft, and a heat exchange pipe having both ends communicated with and connected to a portion inside the hollow roll of each partitioned hollow hole of the hollow shaft and performing heat exchange within the hollow roll, the hollow shaft having a heat exchange pipe between the hollow rolls. In addition, the inside of the hollow roll is reduced to below atmospheric pressure and a liquid is sealed inside, and the liquid level and the heat exchange pipe are when the hollow roll is held horizontally. A heat recovery roll characterized in that it does not come in contact with the other parts. 2. The heat recovery roll according to claim 1, wherein the liquid is water. 3. The hollow shaft has a plurality of hollow holes that are partially closed and partitioned by the part inside the hollow roll, and each partitioned hollow hole has a part inside the hollow roll that is a separate heat exchange pipe. The heat recovery roll according to claim 1, characterized in that the rolls are connected in communication. 4. A single hollow hole is formed at one end in the axial direction of the hollow shaft, and a plurality of hollow holes are formed at the other end, and the hollow holes on both sides are partitioned by a portion inside the hollow roll, and Claim 1, wherein the partitioned hollow holes are connected to each other by an independent heat exchange pipe that communicates with each of the plurality of hollow holes at the other end of the hollow roll. Roll for heat recovery.