JPS5813801B2 - Solid heat recovery method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently recovering sensible heat possessed by solid heat having an unspecified shape.

Rolled steel sheets from steel mills, blast furnace slag, baked coke, castings,
Solid objects of unspecified shape, such as forged products, contain a considerable amount of thermal energy during production, but because it is difficult to recover that thermal energy, a large amount of thermal energy is often wasted.

Among these, heat recovery from coke has entered the stage of implementation, and its outline is shown in Figure 1.

Approximately 1000 degrees Celsius after calcination transported by coke car 11
After the coke 1 is lifted by a crane 12, it is introduced into an inlet 14 of a solid-gas heat exchange chamber 15 by an overturning device 13.

The input port 14 is gas-sealed except when charging.

In the solid air heat exchange chamber 15, the high temperature coke 1 is
After giving heat to the circulating inert gas, it is discharged from the discharger 16, and the cooled coke 2 is sent to the next process.

The inert gas to which the heat has been transferred passes through the duct 17 and transfers the heat to the evaporation tube 18, and then is returned to the solid-gas heat exchange chamber 15 by the blower 19.

The steam generated in the evaporator tube 18 is separated from the liquid in the steam drum 21, and then sent to the consumer through the line 4.

3 is the boiler water introduction line.

In this method, there is two gas-solid wall heat transfer from the coke to the inert gas and from the inert gas to the evaporator tube.

The heat conductivity between the gas and the solid wall is extremely low, and the amount of heat retained per cubic volume of the gas is also small, so measures such as increasing the gas wind speed and volume, or increasing the temperature difference between the gas and the solid wall are recommended. As a result, the equipment had to be large and the steam pressure generated was not high, so its utility value was low.

According to actual results, only 58.5 tons of 21.5k9/Cr/LG, 228°C steam can be obtained per hour from 112.5 tons of coke at about 1000°C.

The present inventors have conducted repeated research to increase the heat transfer coefficient from a solid body of unspecified shape in order to recover the heat held by the solid body, and to generate high-pressure steam using small equipment. It is possible to use a liquid (molten salt) instead of , and to collect the molten salt that adheres to the solid and escapes.
The present invention was achieved by discovering that a method of recovering molten salt by providing a washing step, returning washing water to the molten salt tank, and evaporating the water satisfies the above objective.

In other words, the present invention involves the process of immersing a high-temperature solid of an unspecified shape into a molten salt in a molten salt tank, and after transferring heat to the molten salt, the high-temperature solid is pulled up from the molten salt and sent to a cleaning tank to clean its surface. a step of washing off the molten salt adhering to the molten salt with a cleaning solution; a step of collecting the molten salt by sending the molten salt washed off in the washing tank to the molten salt tank together with the washing solution and evaporating the washing solution; The present invention relates to a solid heat recovery method characterized by comprising a step of recovering steam generated in an evaporation tube immersed in molten salt in a salt tank.

The present invention will be explained in more detail using FIG.

The high temperature solid 1 is immersed in the molten salt tank 22, and after the heat of the high temperature solid 1 is transferred to the lower temperature molten salt 6, the solid is immersed in the molten salt tank 2.
2 and sent to the washing water tank 23, and after washing off the molten salt adhering to the solid with washing water from the line 5, the cooled solid 2 is sent to the next process.

The molten salt washed off from the solids in the washing water tank 23 is sent little by little along with some washing water to the molten salt tank 22 through a line 24, where the washing water is evaporated and the molten salt is recovered.

An evaporation tube 18 is provided in the molten salt 6, and the steam generated in the evaporation tube 18 is led to a steam drum 21, where the liquid is separated and then sent to a consumer through a line 4.

The evaporator tube 18 may be immersed in the upper part of the molten salt 6 in the molten salt tank 22 to utilize the natural circulation of the molten salt, or the evaporator tube 18 may be in contact with the high temperature molten salt 6 circulated by a forced circulation device. do.

The thermal conductivity between a liquid and a solid is several tens of times higher than that between a gas and a solid, and the heat capacity per unit volume of a liquid is about 1,000 times that of a gas, so heat can be transferred with a smaller device and a smaller temperature difference than conventional ones. , it can produce higher pressure steam, so it has great utility value.

Although it depends on the type of molten salt, in general, if the temperature of the molten salt is raised by about 50° C. from its melting point, its viscosity becomes almost that of water, and there is no problem in carrying out convective transfer.

EXAMPLE FIG. 3 shows an example in which the method of the present invention is applied to a high-temperature thick steel plate (approximately 1000° C.) after rolling.

While the high-temperature steel plate 1 is held on a chain-type conveyor 26 and transported through the bottom of the molten salt tank 22, heat is transferred to the molten salt 6, and then taken out from the molten salt 6, and then passed through the washing water tank 23. Molten salt adhering to the steel plate is washed off during transportation.

Thereafter, when it is taken out of the water, it is further washed in a shower 25 using water from line 5, and sent along line 2 to the next process.

The chain type conveyor is endless, and after releasing the steel plate, it returns to its original position guided by guide rollers 27 and conveys the steel plate again.

Although the figure shows only a few guide rollers, there are actually many, some of which serve as drive rollers.

An evaporation tube 18 is immersed in the molten salt 6 in the molten salt tank 22, and the steam generated in the evaporation tube 18 is transferred to the steam drum 2.
After being separated from the liquid in step 1, it is taken out through line 4 and used.

Line 3 is a boiler water introduction pipe. The molten salt selected along with the steel plate in the cleaning water tank 23 is returned to the molten salt tank 22 along with some water through the recovery pipe 24, and
The water evaporates and the molten salt is recovered.

For example, caustic soda can be used as the molten salt.

Caustic soda has a melting point of 328°C and a boiling point of 1390°C and 897°C.
The vapor pressure at this time is 10 mmHg, and the melting point of a mixture of caustic soda and 10% soda carbonate falls to 286°C.

Using this latter molten salt, when one ton of steel plate at 1000°C was cooled to 350°C in the molten salt kept at 320°C, 7
5kg/cm2g. 300℃ steam.

We were able to recover 11 tons (71,500 Kcal).

Examples to which the method of the present invention can be applied are 1. Heat recovery from fired coke, 2. Heat recovery from blast furnace slag, 3. Heat recovery from castings,
4. Heat recovery after forging, 5. There is heat recovery after coal combustion, etc.

As described above, in the method of the present invention, high-pressure steam can be produced from solid waste heat that has been discarded up to now, and this can be recovered as high-level energy by using it for power generation or the like.

[Brief Description of the Drawings] Fig. 1 shows a flow sheet for conventional coke heat recovery, Fig. 2 shows a flow sheet for solid heat recovery of the present invention, and Fig. 3 shows a specific example of the present invention. This is a flow sheet showing.

Claims (1)

[Claims] 1 A process in which a high-temperature solid of unspecified shape is immersed in molten salt in a molten salt tank, and after heat is transferred to the molten salt, the high-temperature solid is pulled up from the molten salt and sent to a cleaning tank to remove the molten material that has adhered to its surface. a step of washing off the salt with a cleaning solution, a step of collecting the molten salt by sending the molten salt washed off in the washing tank to the molten salt tank together with the washing solution and evaporating the washing solution, and a step of recovering the molten salt by evaporating and dispersing the washing solution; A solid heat recovery method comprising the step of recovering steam generated in an evaporation tube immersed in molten salt.