JP5261013B2 - Superheated steam circulation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy-saving type superheated steam circulation system having a high heat recovery ratio. <P>SOLUTION: This superheated steam circulation system comprises a heat treatment furnace 3 for changing the saturated steam produced by a boiler 1 to the superheated steam via a superheating furnace 2, and performing heat treatment on a treated object by the superheated steam, the excess superheated steam discharged from the heat treatment furnace 3 is allowed to pass through a heat exchanger 5, so that the saturated steam produced in the boiler 1 can be heated by the heat exchanger 5; and further, the excess superheated steam is allowed to pass through a hot water generator 6 so that the water is changed into hot water in the hot water generator 6 and can be supplied to the boiler 1. A return pathway Ra is disposed for returning a part of the excess superheated steam discharged from the heat treatment furnace 3 to an upstream side of the superheating furnace 2, thus the loss of the used steam can be reduced, and new supply of the saturated steam from the boiler 1 can be suppressed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an energy-saving superheated steam circulation system.

Conventionally, as disclosed in Patent Document 1, there is a heat treatment apparatus capable of performing a tempering process by heating a workpiece to a predetermined temperature with superheated steam.
JP 2007-231367 A

  In the heat treatment apparatus disclosed in Patent Document 1, heat treatment can be performed while preventing oxidation of the object to be treated, but the heat recovery rate of the excess superheated steam after the heat treatment is not sufficient, and heat energy is wasted. There was a problem of being done.

An object of the present invention is to provide an energy-saving superheated steam circulation system having a large heat recovery rate, and the following measures have been taken in order to achieve at least a part of this object.
The present invention is a system equipped with a heat treatment furnace capable of heat-treating an object to be treated in a low oxygen state by making saturated steam produced by a boiler into superheated steam via a superheated furnace, and filling the superheated steam.
On the downstream side of the heat treatment furnace of the circulation path in which the boiler, the superheat furnace, and the heat treatment furnace are sequentially arranged from the upstream side toward the downstream side, using surplus superheated steam discharged from the heat treatment furnace, A heat exchanger for warming the saturated steam generated in the boiler, and a hot water generator for producing hot water to be supplied to the boiler ;
A circulation path between the boiler and the superheater furnace is provided with a heat exchange path that sends saturated steam to the heat exchanger and warms it back, and the circulation path between the inlet side and the outlet side of the heat exchange path is the first in the circulation path. 1 valve is provided, a second valve is provided in the heat exchange path between the inlet side of the heat exchange path and the heat exchanger,
The gist is that a return path is provided for returning a part of the excess superheated steam from the upstream side of the heat exchanger to the outlet side of the heat exchange path and into the circulation path between the superheater.

In the present invention, by using the excess superheated steam discharged from the heat treatment furnace, the saturated steam at 100 ° C. generated by the boiler can be heated to about 300 ° C. through the heat exchanger and supplied to the superheat furnace.
In addition, by using the heat of excess superheated steam, room temperature water can be changed to warm water with a hot water generator and supplied to the boiler. Since the boiler can generate saturated steam from warm water, Compared with the case where saturated steam is generated, less heat energy is required, the heat of the excess superheated steam can be effectively used as a whole, the heat recovery rate of the entire system is increased, and an energy saving superheated steam circulation system is obtained.
In addition, it is possible to reduce the loss of used steam due to some excess superheated steam that is returned to the superheated furnace through the return path, and to suppress the supply of new saturated steam from the boiler. It becomes.

Next, the best mode for carrying out the present invention will be described using examples.
FIG. 1 is a schematic layout diagram of a superheated steam circulation system.
In the superheated steam circulation system, a boiler 1, a superheat furnace 2, and a heat treatment furnace 3 are arranged in the circulation path R from the upstream side to the downstream side, and further, a heat exchanger is disposed in the circulation path R. 5 and a hot water generator 6 are provided.

In the boiler 1, general saturated steam at 100 ° C. is generated as the primary steam, the generated saturated steam is supplied into the superheated furnace 2 on the downstream side, and the saturated steam is heated by the heater in the superheated furnace 2, The superheated steam in a dry state with an increased amount of heat is generated, and the superheated steam that exits the superheated furnace 2 is supplied into the heat treatment furnace 3 on the downstream side.
In the heat treatment furnace 3, heat treatment is performed on an object to be treated such as a steel material or a non-ferrous metal with the supplied superheated steam.
In addition, food etc. can also be heat-processed as a to-be-processed object.

The superheated steam supplied to the heat treatment furnace 3 expels air in the heat treatment furnace 3, that is, oxygen, and the heat treatment furnace 3 is filled with H ₂ O, which is superheated steam. Steel materials and the like that are heat-treated in this state are in a state where there is little rusting, and heat treatment that can suppress the progress of rusting can be performed.
Also, when the object to be processed is a food, it can be heat-treated without oxidizing the food.

Conventionally, an inert gas such as nitrogen gas is put into the heat treatment furnace 3 to prevent oxidation of the object to be treated, but it is not necessary to put such an inert gas into the heat treatment furnace 3. Heat treatment can be performed in a low oxygen state in the heat treatment furnace 3 with superheated steam.
Further, since the superheated steam has high heat radiation performance, the workpiece can be heated at a speed 1.5 to 2 times faster than when the combustion exhaust gas is used as a heating source. Therefore, even if this heat treatment furnace 3 is relatively small, heat treatment can be efficiently performed inside.

The surplus superheated steam discharged from the heat treatment furnace 3 has a temperature of about 400 ° C. to 700 ° C. depending on the object to be treated. This surplus superheated steam is circulated by the rotation of the fan 4 provided in the circulation path R. The excess superheated steam flows into the heat exchanger 5 through the path R to the downstream side.
In this heat exchanger 5, a heat exchange path 5a is arranged, and saturated steam at 100 ° C. generated in the boiler 1 through the heat exchange path 5a is supplied, and superheated steam at about 400 ° C. to 700 ° C. is supplied. As a result, the saturated steam from the boiler 1 is warmed in the heat exchanger 5, and the saturated steam from the boiler 1 reaches a temperature of about 300 ° C. and is supplied to the superheated furnace 2.

Further, a hot water generator 6 is provided on the downstream side of the heat exchanger 5, and the hot water generator 6 can warm water at room temperature with excess superheated steam to make hot water. The hot water produced by the hot water generator 6 is supplied to the boiler 1, and the boiler 1 can produce saturated steam with energy saving compared to the case of producing saturated steam from room temperature water, and the boiler 1 can be downsized. It will be a thing.
Note that the hot water generator 6 is configured such that a part of the excess superheated steam can be discharged to the outside.

In addition, a plurality of valves are arranged in the circulation path R of this example, and a valve 71 is provided in the heat exchange path 5a toward the heat exchanger 5, between the inlet side and the outlet side of the heat exchange path 5a. Is provided with a valve 72, a valve 73 is provided upstream of the fan 4, and a valve 74 is also provided between the heat exchanger 5 and the hot water generator 6.
Further, a return path Ra is provided so as to return a part of the excess superheated steam from the circulation path R between the fan 4 and the heat exchanger 5 to the upstream side of the superheating furnace 2, and the return path Ra passes through the return path Ra. Since the excess superheated steam having a temperature of about 700 ° C. is returned into the superheated furnace 2, the power of the heater or the fuel consumption of the superheated furnace 2 can be reduced by effectively using the amount of heat of the excess superheated steam in the superheated furnace 2. In addition, the excess superheated steam returned to the superheated furnace 2 can reduce the loss of the used steam (moisture), and the supply of new saturated steam from the boiler 1 can be suppressed. As a whole, surplus superheated steam can be used effectively, and the heat recovery rate is extremely high, resulting in a superheated steam circulation system with a large energy saving effect. Moreover, the boiler 1, the superheated furnace 2, and the heat treatment furnace 3 can be downsized.

It is a schematic arrangement block diagram of a superheated steam circulation system.

DESCRIPTION OF SYMBOLS 1 Boiler 2 Superheated furnace 3 Heat treatment furnace 4 Fan 5 Heat exchanger 5a Heat exchange path 6 Hot water generator 71, 72, 73, 74 Valve R Circulation path Ra Return path

Claims (1)

In a system provided with a heat treatment furnace that can treat saturated steam generated by a boiler as superheated steam through a superheated furnace, heat the processed object in a low oxygen state by filling the superheated steam,
On the downstream side of the heat treatment furnace of the circulation path in which the boiler, the superheat furnace, and the heat treatment furnace are sequentially arranged from the upstream side toward the downstream side, using surplus superheated steam discharged from the heat treatment furnace, A heat exchanger for warming the saturated steam generated in the boiler, and a hot water generator for producing hot water to be supplied to the boiler ;
A circulation path between the boiler and the superheater furnace is provided with a heat exchange path that sends saturated steam to the heat exchanger and warms it back, and the circulation path between the inlet side and the outlet side of the heat exchange path is the first in the circulation path. 1 valve is provided, a second valve is provided in the heat exchange path between the inlet side of the heat exchange path and the heat exchanger,
A return path is provided for returning a part of the excess superheated steam from the upstream side of the heat exchanger to the circulation path between the outlet side of the heat exchange path and the superheated furnace. Circulation system.

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