JPS5839714A - Recovering method for heat from waste gas of hot stove - Google Patents

Abstract

PURPOSE:To recover the sensible heat of the waste gases of hot stoves and to utilize the heat for preheating of blasting air by applying the heat obtained in a heat exchanger provided in the lower part of the hot stove in a combustion period to a heat exchanger provided in the lower part of the hot stove in a blasting period by means of a heat medium. CONSTITUTION:A plate type heat exchanger 3a is provided on the brick hardware 2 in the lower part of a regenerating chamber 1 of a hot stove. A piping 6 for introduction of a heat medium (for example, air, synthetic oil, etc.) is connected on one side of the heat exchanger 3a and a piping 8 for discharging the same on the other side. Stop valves 7, 9 are provided respectively thereto. Then the sensible heat of the waste gases of combustion in the chamber 1 of the hot stove in a combustion period is utilized for preheating of blasting air with the heat exchanger 3a, and the preheated blasting air is fed to the heat exchanger 3a in the chamber 1 of the hot stove in a blasting period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering heat from hot-blast stove exhaust gas in order to use the heat of hot-blast stove exhaust gas in the combustion period to preheat blast air (cold air) of the hot-blast stove in the blowing period. It is something.

A hot blast furnace consists of a combustion chamber and a heat storage chamber. During the combustion period, the sensible heat of the combustion gas is stored in the heat storage bricks of the heat storage chamber, and then during the blowing period, cold air is passed through the heat storage chamber for heat exchange. This hot air is then supplied to the blast furnace.

This hot blast furnace is usually installed with one J-41 unit per one blast furnace, and the combustion period and the blowing period are switched sequentially, and the hot blast furnace is in charge of continuously supplying hot air at a constant temperature to the blast furnace. The combustion exhaust gas of the furnace has sensible heat up to 200°C, but the sensible heat of the combustion exhaust gas is only used for preheating the combustion air by the exhaust gas heat recovery 70 sheet shown in Figure 1. @This collection system is the first
An exhaust system pipe is provided on the heat storage chamber side of each hot air stove such as No. 1 to No. 2, and a fuel supply pipe and combustion air supply pipe are provided on the combustion chamber side. A recovery device (heat exchanger) is provided, and a side pipe provided in the air supply pipe is connected to the exhaust heat recovery device.

Note that Sv indicates a flue valve, Ov indicates a cold air valve, and HV indicates a hot air valve.

This invention provides an effective method for recovering heat from hot blast furnace exhaust gas, in which the sensible heat of combustion exhaust gas discharged from a plurality of hot blast furnaces is used to preheat blast furnace blast air (cold air) to be sent to the hot blast furnaces. Its purpose is to provide.

However, the gist of this invention is as follows.

In other words, a heat exchanger is installed at the bottom of the heat storage chamber of each of the hot-blast stoves during the blowing season and the hot-blast stove during the combustion season, and the heat exchangers are connected by heat medium distribution piping, so that the heat medium is heated at the same temperature. It is characterized by preheating the blast by circulating the flow through an exchanger and imparting the sensible heat of the exhaust gas from the hot-blast stove in the combustion period to the blast to be sent to the hot-blast stove in the blowing period via a heat medium. A method for recovering heat from hot blast furnace exhaust gas.

Next, the present invention will be explained based on the hot blast furnace exhaust gas heat recovery 70-sheet shown in FIG.

The drawing schematically shows a hot-blast stove in the combustion phase and a hot-blast stove in the blowing phase. A heat exchanger is provided at the bottom of the heat storage chamber of each wind furnace, and these heat exchangers are connected by a single heat medium distribution pipe. The heat medium is circulated by a pump (or fan).

While the flue gas passes through the heat exchanger, its sensible heat is recovered by the heating medium and escapes to the flue through the flue valve Sv. On the other hand, in the hot blast furnace during the blowing season, the blast air sent from the blast furnace blower and already at a temperature of about 2oo"C passes through the heat exchanger, during which time the blast air is preheated and then passes through the heat storage chamber. After passing through the hot air valve HV, it becomes hot air of about 300°C and is sent to the blast furnace.In this way, the heat obtained from the heat exchanger installed at the bottom of the hot air stove during the combustion period is transferred to the hot air stove during the blowing period. so as to give it to the heat exchanger installed at the bottom of the
The heat exchanger of the hot-blast stove during the combustion period and the heat exchanger of the hot-blast stove during the blowing period are exchanged via the heat medium flowing between them, thereby reducing hot-blast stove exhaust gas. This sensible heat is recovered and used to preheat the blast.

Seven examples of recovery patterns of sensible heat from hot blast furnace exhaust gas according to the present invention are shown in Section J! I! Shown in J.

As shown in Fig. 3, the exhaust heat recovery operation according to the present invention is carried out by reducing the temperature of the blast air (approx. It is carried out within the temperature range of the control temperature (about soo'c).For example, if the humidity is lower than 100"C, which corresponds to the blast humidity, the blast humidity Since recovery at temperatures below that temperature is ineffective, the circulation of the heating medium is stopped and the recovery operation is stopped.

In order to lengthen the l-cycle time shown in Figure 3, the load on the pump shown in Figure 1 can be increased to increase the amount of heat exchanged by increasing the amount of circulating heat medium. .

In addition, in Figure 1, for ease of explanation, each of the hot air stoves that are burning and the hot air stove that is blowing air are shown. ! It is clear that the invention can be implemented with several hot air stoves as well.

Next, an example of the arrangement of the hot air stove of the heat exchanger used in the method of the present invention will be explained with reference to FIG.

Figure 4 shows an example of using a plate heat exchanger, where l indicates the heat storage chamber of the hot air stove, C indicates the brick hardware installed at the bottom, and Ja indicates the heat exchanger. be·
In the plate type heat exchanger 1ira, the brick support is placed on top of the metal plate, and this arrangement is similar to the iron plate at the bottom of the heat storage chamber l.
This is done by means of a twisting connection, but on the other hand an expansion joint 3
This allows for absorption of thermal expansion, etc.

The plate heat exchanger C has a heat medium (for example, a gas medium such as air or a liquid medium such as synthetic oil) introduction pipe 1 connected to one side, and a discharge pipe t connected to the other side. ! M valve and f are provided. io is a flow rate control valve, // is a branch pipe for installing a pressure gauge, etc., lko is a flue valve, J is a cold air valve, and ltei is a support.

Note that the plate surface of the heat exchanger J may be a one-piece structure having a large number of exhaust gas passage holes and completely covering the lower part of the heat storage chamber, or may have a plate structure divided into a plurality of parts.

Figure 1 shows an example of using a pipe heat exchanger.
is a Pei-1 type heat exchanger, which has a large number of heat transfer pipes l.
One end is a fixed end and serves as a collecting pipe 14, and the other end is an expansion joint I, and 7.
Lunge connected. t.

9*10e/kot/3e/4' is the same as that in the reference figure.

Although not shown, the heat transfer pipe on the left side of the figure (13 people side) has a single pipe configuration similar to the discharge side piping in t, and the heat medium is divided into limbs in this part, and each heat transfer Pipe l! It is intended to be diverted to

The effects of the present invention can be summarized as follows.

(1) The sensible heat of the exhaust gas from the hot air stove can be effectively recovered and used.

In contrast to the system in which the sensible heat of combustion exhaust gas is recovered and used for preheating the combustion air, in the present invention, the sensible heat is recovered and used for preheating the blast, so the heat exchange is direct, and therefore the sensible heat is used. The effect is greater. Also, since the blast is preheated,
The coke ratio is directly reduced.

(2) High temperature air can be blown.

At the bottom of the hot blast furnace's heat storage chamber, there is a guitar holder and a flue valve, so the temperature of the exhaust gas is controlled at 300 degrees Celsius or less. Therefore, combustion must be stopped above this temperature. However, in the present invention, a heat exchanger is installed at the bottom of the hot air stove to perform heat exchange.
It is possible to prevent the exhaust gas temperature from rising without stopping combustion, and therefore the combustion and heat storage time can be extended.
It is possible to blow air at a higher temperature.〇(3) The frequency of switching the hot-blast stove is reduced - The combustion time of the hot-blast stove can be extended, and the sensible heat of the exhaust gas can be fully utilized, so the frequency of switching can be reduced.

(4) Fluctuations in furnace conditions are reduced.

Since the frequency of switching the hot blast furnace is reduced, the number of pressure fluctuations during pressure filling of the hot blast furnace is reduced, and therefore fluctuations in furnace conditions are also reduced.

[Brief explanation of the drawing]

Fig. 1 shows the 7 sheets of conventional heat recovery from hot air stove exhaust gas, and No. 7 shows the 7 sheets of heat recovery from hot air stove exhaust gas according to the present invention.
0-Sheet, Figure 3 is a graph showing a pattern of sensible heat recovery from hot blast furnace exhaust gas according to the present invention, and Figure 3 is a longitudinal section showing an example of arrangement of a plate heat exchanger used to carry out the present invention. The top view and FIG. L... Heat storage chamber of hot air stove, K... Brick holder, Ja
...Plate heat exchanger, Jb...Pipe heat exchanger, Tei...Hot stove iron shell,! ...Expansion joint, 6...
Heat medium introduction pipe, ri...on/off valve, t...heat medium discharge pipe, t...on/off valve, 10...flow control valve, ///
... Branch pipe for installing pressure gauges, etc., /2 ... Flue valve, /3.
...Cold air valve, llI...Strut, 15...Heat transfer pipe, /&...Collecting pipe, /7...Expansion joint. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] 1. A heat exchanger is installed at the bottom of the heat storage chamber of each hot-blast stove during the blowing season and the hot-blast stove during the combustion season, and the heat exchangers are connected with heat medium distribution piping to efficiently exchange the heat medium. It is characterized by preheating the blast air by circulating the flow through the heating medium and applying the sensible heat of the exhaust gas from the hot blast stove during the combustion period to the blast air sent to the hot blast stove during the blowing period. A method for recovering heat from hot blast furnace exhaust gas.