JPS5817397B2 - Scrap preheating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to equipment for preheating scrap raw material in a melting furnace which supplies scrap as raw material.

When supplying scrap as raw material to a melting furnace, the waste gas from the melting furnace is used to preheat the scrap (this is thought to be a way to save energy in the operation of the melting furnace).

However, with conventional scrap preheating equipment, the exhaust gas from the melting furnace is simply vented through the scrap in the preheater to heat it, so heating lowers the exhaust gas temperature, which reduces the amount of oil and fat contained in the scrap. combustible components such as plastics, etc., and odor components resulting from the decomposition of plastics, etc., are emitted into the atmosphere without being burned or thermally decomposed, resulting in a problem that significantly deteriorates the environment.

In addition, in such preliminary equipment, the exhaust gas temperature is lowered by the air sucked through the air leakage portion such as the elbow seal portion, which has also been a factor in inhibiting the utilization of the exhaust gas.

The present invention has been made in view of the above-mentioned actual situation, and includes a melting furnace, a combustion furnace for combusting exhaust gas from the melting furnace, and an elbow seal portion provided in the piping between the melting furnace and the combustion furnace. a preheater that preheats scrap with gas from the combustion furnace; a cracking furnace that burns combustible components and decomposes odor components contained in the preheated gas from the preheater;
a pilot burner provided in the cracking furnace to branch and guide gas from the combustion furnace to form a high-temperature pilot flame; an air heater that heats air from a blower with the high-temperature gas from the cracking furnace; The present invention relates to a scrap preheating equipment characterized by comprising: a heated air pipe that guides heated air from an air heater to the elbow seal portion t.

The present invention will be described in detail below with reference to the drawings.

The drawing is a flow sheet showing the outline of the present invention, in which exhaust gas (usually 830
A combustion furnace 2, which is designed to completely combust the CO in the atmosphere (approximately 850°C to 850°C) and eliminate the risk of explosion, and is fully equipped with the function of a pre-duster, is connected via an elbow 3 and an exhaust gas pipe 4. A preheater 5 for preheating the scrap with preheating gas from the combustion furnace 2 is connected to the combustion furnace 2 via a preheating gas pipe 6. A decomposition furnace 7 is connected via a preheated gas pipe 8 to heat-treat the preheated gas containing combustible components and odor components generated from oil, plastic, etc. contained in the scrap.

The decomposition furnace 7 is equipped with a pilot burner 9 at its upper part, which acts as a pilot flame.

The pilot burner 9 has a fuel introduction section 10 that supplies kerosene and oxygen, a combustion air introduction section 12 that is equipped with an air preheater 11 and supplies preheated air, and a part of the preheating gas pipe 6 branched off. A columnar flame is formed in the decomposition furnace 7 by supplying a high-temperature gas introduction part 13, and the preheated gas from the preheater 5 is brought into direct contact with the decomposition furnace γ, and the temperature inside the decomposition furnace γ is kept at about 750° C. or more. I try to hold as many beads as possible.

The decomposition furnace 7 is connected to an air heater 15 via piping 14 to enable heat exchange between the gas heated by the trowel and the air supplied from the blower 16. a gas cooler 17 for protecting the heat-recovered gas from a dust collector;
The piping is configured so that it can be discharged to the atmosphere from a chimney 21 via a dust collector 1B, a control damper 19, and an exhaust fan 20 in this order.

Furthermore, a hood 3' is provided on the elbow 3, and the heated air pipe 22 from the air heater 15 is connected to the hood 3' to supply heated air to the elbow 3, thereby eliminating air leakage in the elbow 3. Prevent outside air (cold air) from being sucked in from the entrance.

In addition, 23 and 24 in the figure are used to control the decomposition furnace 7 by adjusting the amount of gas introduced into the preheater 5 and the amount of gas introduced into the pilot burner 9.
1 is a damper for ensuring the temperature necessary for burning the combustible components of the scrap exhaust and decomposing the odor components.

In the above configuration, the preheating gas discharged from the electric furnace 1 via the pipe 4 and burned in the combustion furnace 21 is introduced into the preheater 5 via the pipe 6 to preheat the scrap in the preheater 5.

Due to this preheating, the preheated gas has a low temperature and is guided to the cracking furnace T through the pipe 8 while containing combustible components such as oil and odor components such as plastic snacks mixed in the scrap.

The gas introduced into the cracking furnace 7 is effectively combusted by directly contacting the combustible components it contains with the high-temperature columnar flame formed in the cracking furnace T, and eliminates the cause of odor. Odor components such as methyl sulfide, methylamine, ammonia, and acetaldehyde are decomposed by high-temperature heating in the decomposition furnace 7, which is maintained at a temperature of about 750° C. or higher, and converted into odorless substances.

At this time, it is preferable that the temperature inside the decomposition furnace 7 is 800° C. or higher.

The gas that has been burned and decomposed in the decomposition furnace 7 is transferred to the pipe 14.
The air is introduced into the air heater 15 through the air heater 15, and the air passed through the air heater 15 and sent from the blower 16 is heated and heated by heat exchange.

This heated air is guided by the heated air pipe 22 to the hood 3' of the elbow 3, which acts to block the cold air drawn from the air leakage part of the elbow 3 and to draw the heated air itself.

The amount of heated air to be supplied is adjusted by adjusting the pressure of the blower 16 (including the use of a controller L/tough bar 19) and adjusting the hood 3'.

Since the heated air is sucked through the air leakage portion in this way, it is possible to prevent the temperature of the scrap preheating gas from decreasing, that is, to increase the temperature of the preheating gas, thereby improving the effect of preheating the scrap.

Therefore, the temperature of the preheated gas introduced into the cracking furnace 7 via the pipe 8 is also increased, so that the amount of fuel supplied from the fuel introduction section 10 is reduced, the amount of combustion air is reduced, and the air preheater 11 and the air preheater 11 (not shown) are accordingly reduced. The combustion and decomposition functions can be improved by reducing the size of the furnace and increasing the temperature inside the decomposition furnace 7.

Furthermore, by branching a part of the preheating gas pipe 6 and leading it to the pilot burner 9, a high-temperature pilot flame can be formed in the pilot burner 9, thereby effectively increasing the combustion and temperature inside the cracking furnace 7. can be done.

Furthermore, the high temperature gas introduced into the pilot burner 9 through the high temperature gas introduction section 13 is generated during mass sales when the preheating gas is necessary for preheating the scrap, so it is recommended to use this surplus. ing.

After the heat has been recovered by the air heater 15, the gas is cooled by the gas cooler 1T to a temperature that does not cause any trouble to the dust collector 18, and then collected by the dust collector 18 and then controlled. While the suction force is adjusted by the damper 19, the air is sucked in by the exhaust fan 20 (trowel) and discharged into the atmosphere from the chimney 21.

By the way, conventionally, the suction by the exhaust fan 20 was increased by about ioo% of the amount of exhaust gas in the electric furnace 1, which resulted in unnecessary excessive air being sucked into the electric furnace 1.
This results in excessive energy loss, but in the present invention, the amount of leaked air is less than half of the conventional amount. By supplying heated air to the preheating section, the gas temperature of the entire preheating circuit can be raised, and therefore the temperature of the scrap can be easily and quickly raised, and the functionality of the cracking furnace 7 can be improved. This can improve the overall heat recovery effect.

Incidentally, in the above embodiment of the present invention, a heated air pipe 22 and a hood 3' were provided so as to supply heated air to the air leakage part of the elbow 3, but as shown by the imaginary line in the figure,
A hood 1' is provided for the air leakage part of the electric furnace 1, and a hood 5' is provided for the air leakage part of the preheater 5, as necessary.
In addition, by supplying heated air through branch pipes 22' and 21' from the heated air pipe 22, the preheating effect of the scrap can be further improved.

Furthermore, it goes without saying that the present invention can be applied to various devices for preheating scrap, and that various other changes can be made without departing from the gist of the present invention.

As described above, according to the present invention, (i) The combustion of combustible components and the decomposition of odor components generated in the gas by preheating the scrap can be effectively carried out in the cracking furnace, thereby solving the problem of pollution caused by exhaust gas. It is possible to prevent the occurrence of waste, and expand the range of scrap usage, contributing to waste treatment and resource conservation.

(II) Use of exhaust gas from the cracking furnace Therefore, it is possible to improve the preheating effect, maintain the high temperature of the cracking furnace, and improve combustion.
The decomposition effect can be improved.

(Since high-temperature gas from the combustion furnace is introduced into the cracking furnace, the temperature inside the cracking furnace can be increased and the functionality of the cracking furnace can be improved.

eV) Can be easily applied and implemented in similar technical fields, whether new or existing.

Demonstrates excellent effects such as

[Brief explanation of drawings]

The drawing is a flow sheet showing an embodiment of the invention. 1... Electric furnace, 2... Combustion furnace, 3...
...Elbow, 5...Preheater, 7...
・Decomposition furnace, 9...Pilot burner, 13...
...High temperature gas introduction section, 15...Air heating chamber, 16...Blower, 22...Heating air piping.

Claims (1)

[Claims] 1. A melting furnace, a combustion furnace that burns exhaust gas from the melting furnace, an elbow seal provided in the piping between the melting furnace and the combustion furnace, and a preheating of scrap with the gas from the combustion furnace. a decomposition furnace that burns combustible components and decomposes odor components contained in the preheated gas from the preheater; and a decomposition furnace that branches and guides the gas from the combustion furnace to form a high-temperature pilot flame. a pilot burner installed in the decomposition furnace f, an air heater that heats air from the blower with high-temperature gas from the decomposition furnace, and heated air that guides the heated air from the air heater to the elbow seal portion. Scrap preheating equipment featuring Kokichi, equipped with piping, and.