JPH01164715A - Production of carbon dioxide - Google Patents

Abstract

PURPOSE:To avoid a decrease in the concn. of CO2 in an exhaust gas and to obtain CO2 having fixed compsn., by releasing the exhaust gas of a hot-blast stove decreased in the concn. of CO2, in the air without introducing to a stack pipe, when air blast and combustion in the hot-blast stove are switched. CONSTITUTION:When the combustion is switched over to the air blast in the air-blast stove HS-1, stack valves V1 and V2 are opened and other valves are shutted, and when the combustion process is finished the supply of combustion gas and air for combustion is stopped. And then, the valves V1 and V2 are shutted and the pressure of other air-blast stoves having atmospheric pressure at the time is increased to e.g., 2K, by opening blasting valve V4 and by letting flow from the air-blast stove HS-1 to other air-blast stove through a equalizing pipe 6. Then, by shutting the valve V4 and opening the valve V5, the pressure of other air-blast stove is increased to e.g., 4K and hot air blast 2 to a blast furnace is started. By this way, in switching between air blast and combustion in the hot-blast stove HS-1, the concn. of the product CO2 is kept constant without introducing the exhaust gas decreased in the concn. of CO2 to the stack pipe 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing carbon dioxide gas, which separates and recovers carbon dioxide gas from the combustion exhaust gas of a hot blast furnace.

[Prior Art] In recent large-scale blast furnaces, four hot blast furnaces are usually arranged in one blast furnace, and a blowing process and a combustion process are alternately repeated. In the blowing process, air is forced into the hot blast furnace where heat has been stored in the combustion process, which is the previous process, where heat is exchanged and the air is turned into hot air and blown into the blast furnace. When the temperature of the hot air falls below the limit, the combustion process is started, and at the same time, the hot blast furnace in another combustion process is moved to the blowing process. Combustion exhaust gas from the hot stove in the combustion process enters the flue pipe,
A part of it is branched and supplied to the carbon dioxide production device.

“Problems to be Solved by the Invention” However, the pressure inside the hot-air stove is high (for example, 4 kg/ad) during the blowing process, and approximately atmospheric pressure during the combustion process. Exhaust the air from the flue valve. At this time,
The concentration of carbon dioxide in the exhaust gas flowing into the flue pipe is reduced.

Therefore, the C2 ratio in the combustion exhaust gas supplied from the flue pipe of the hot air stove to the carbon dioxide production equipment decreases, and the concentration of the produced carbon dioxide fluctuates.

The present invention has been made in view of the above circumstances, and aims to provide a method for producing carbon dioxide gas that avoids a decrease in the carbon dioxide component of combustion exhaust gas when switching between hot blast stoves and obtains a product gas with a constant composition. .

[Means and effects for solving the problems] The method for producing carbon dioxide gas according to the present invention is a method for producing carbon dioxide gas in which carbon dioxide gas is separated and recovered using combustion exhaust gas flowing through a flue pipe of a hot air stove as a raw material gas. The present invention is characterized in that the exhaust gas with a reduced carbon dioxide concentration is not introduced into the flue pipe when switching between blowing and combustion in the furnace, but is dissipated into the atmosphere.

The combustion exhaust gas with a reduced carbon dioxide concentration that is generated when switching between the combustion process and the blowing process of a hot air stove is dissipated into the atmosphere, so there is no risk that the exhaust gas will be introduced into the flue pipe, and the carbon dioxide that is the product gas is Purity remains constant.

[Example] An example of the present invention will be described based on the accompanying drawings. FIG. 1 is a system diagram of gas piping for a hot air stove used in the method of the present invention. Figure 1 shows four hot blast stoves MS-1 to MS-1 for one blast furnace (one of S-4 (H8-1),
2 is a hot air pipe; 3 is a dissipation pipe through which combustion exhaust gas from the four hot air stoves is dissipated through a silencer 4; 5 is a flue pipe through which combustion exhaust gas flows; 6 is used when switching between the blowing process and the combustion process. A pressure equalizing pipe, 7 a blower pipe, and 8 a carbon dioxide production device. Vl and 'V2 are both flue valves that introduce combustion exhaust gas into the flue pipe during the combustion process, ■4 is a blow valve that is communicated with another hot air stove to adjust the pressure at the time of switching, and ■
Reference numeral 5 designates an air blowing valve that forcefully sends air into the hot air stove, which is the heat stored in the air blowing process, and 6 represents an exhaust valve that releases the exhaust gas whose carbon dioxide concentration has been reduced during the switching to the atmosphere through a silencer.

The operation of the hot air stove configured as above will be explained. FIG. 2 shows the opening and closing of the answer valve corresponding to each process of air blowing, switching, and combustion. In this figure, the shaded areas are open and the rest are closed. First, in the ventilation process, the ventilation valve is open and the other valves are closed, and from here the ventilation air flows through approximately 4 kg.
(kg/CId.

Gauge pressure (hereinafter the same applies) is blown into the hot blast furnace where heat has been stored in the previous combustion process, where the heat is exchanged, and then the hot blast is supplied to the blast furnace. When the heat exchange progresses and the hot air temperature falls below the limit, the hot air stove must store heat again in the combustion process, but there is a pressure equalization process and a pressure exhaust process at the time of switching between these steps.

As mentioned above, the hot air stove MS-1 is at a pressure of 4.0 mph during the blowing process, but it is at approximately atmospheric pressure during the combustion process, so it is necessary to reduce this pressure. When switching, be sure to pair H
Contrary to 8-1, there is a hot blast furnace, for example H3-3, which goes from the combustion process to the blowing process, and as a procedure to reduce the pressure in step 4 of H8-1, in order to effectively utilize this pressure, H3-1゜H3 -: 3 Open both blow valves (4) to equalize the pressure of the two hot air stoves to 2k. This is the pressure equalization process.

Next, in the pressure exhausting step, the air filling valve (4) is closed and the air exhaust valve (V6) is opened to release the residual pressure of MS-1 from the silencer 4 to bring it to atmospheric pressure. After this, H8-1 is supplied with fuel gas and combustion air and enters the combustion process.

Next, the process at the time of switching from the combustion process to the blowing process will be described for H8-3 above. This system diagram is the same as H8-1, so the symbols for valves and pipes are the same as in Figure 1. In the combustion process, flue valves V'l and V2 are opened,
The other valves are closed, and when the combustion process is completed, the supply of fuel gas and combustion air is stopped, and the above-mentioned Vl and V2 are closed. At this time, the pressure of H8-3, which is at atmospheric pressure, is When the valve (4) is opened, the pressure is communicated with (Is-1) by the pressure equalizing pipe (6) and becomes 2k. Next, the blowing valve (4) is closed, the blowing valve (5) is opened, the pressure of HS-,3 is set to 4, and then blowing of hot air to the blast furnace is started, and the process moves to the blowing step.

In addition, since the flow rate of flue gas supplied to the carbon dioxide production equipment at the time of switching is usually less than half of the amount of flue gas generated by one blast furnace, other Hot stove such as H8-2 or H3-4
It is fully covered by 6.

To give specific numerical values according to this example, the gas composition of the combustion exhaust gas in the flue pipe is expressed in % under normal conditions as C0
2; 27 to 3 o, N2; 71 to 72.
However, in this example, this decrease was hardly observed.

As described above, when switching hot air stoves, combustion exhaust gas with a reduced carbon dioxide concentration is not introduced into the flue pipe 6.
The concentration of product gas is kept constant.

[Effects of the Invention] According to the present invention, combustion exhaust gas with reduced carbon dioxide concentration is dissipated into the atmosphere through the exhaust valve and silencer and is not introduced into the flue pipe. Purity is stable.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the gas piping of the hot air stove used in the method of the present invention, and FIG. 2 is a diagram showing the opening and closing of the response valves corresponding to each process of air blowing, switching, and combustion of the present invention. 1...Hot air stove, 2...Hot air pipe, 3...Diffusion pipe, 4
...silencer, 5.. flue pipe, 6.. pressure equalization pipe,
7...Blow pipe, 8...Carbon dioxide production device, Vl, V
2... Flue pipe, V4... Air filling valve, ■5... Air blowing valve, ■6... Exhaust valve.

Claims (1)

[Claims] In a carbon dioxide production method in which carbon dioxide is separated and recovered using combustion exhaust gas flowing through a flue pipe of a hot air stove as a raw material gas, the exhaust gas whose carbon dioxide concentration has decreased when switching between blowing and combustion of the hot air stove is passed through the flue pipe. A method for producing carbon dioxide characterized by dissipating it into the atmosphere without introducing it into the atmosphere.