JPS59154108A - Dissociation method of dissolved component in cooling water for treating combustible gas - Google Patents

Abstract

PURPOSE:To dissociate and remove dissolved components in cooling water, to prevent an atmospheric component from penetrating into the water, and to blow off the components into a safe place, by injecting an inert gas into a storage pit storing circulating water for scrubbing and cooling combustible gases. CONSTITUTION:The high-temp. blast furnace gas is sent into a cooling apparatus 3 from a lower part through a line 1. The sent-in blast furnace gas is sucked up by a circulating water pump 9 from a circulating water pit 5, cooled by cooling water sprayed from a cooling water nozzle 4 provided in a gas cooling apparatus 3, and sent to the succeeding stage through an upper main pipe 2. Nitrogen is supplied into a suction pipe 6 through a line 7, and injected into the cooling water to dissociate oxygen from the cooling water stored in the storage pit, and the atmosphere in the upper space of the pit is made to consist mainly of nitrogen. The oxygen etc. mixed with nitrogen is discharged from a discharge port 8 into a safe place, and the danger of an explosion can be completely eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the problem of ignition, which is often caused by directly cooling high-temperature gas containing combustible components, such as blast furnace gas, with cooling water, or by circulating the cooling water. It concerns how to prevent explosions.

It is well known that when the oxygen concentration in a gas containing combustible components increases and reaches an explosive limit, contact with some kind of ignition source will cause ignition or explosion.

For example, when a high-temperature gas containing combustible components is cooled with a water injection direct cooling type gas cooler, the cooling water comes into contact with the high-temperature gas, and dissolved oxygen in the cooling water dissociates and is contained in the high-temperature gas. is replaced with the component that is present.

Therefore, the oxygen concentration in the high temperature gas after cooling increases. On the other hand, as a result of the above-mentioned substitution, high-temperature gas components are dissolved in the cooling water to a solubility that is permissible at the current temperature of the cooling water, but this cooling water is returned to the cooling water storage circle storage bit for circulation use. Then, the temperature of the return cooling water is lowered by the new cooling water and air, and the gas components dissolved in the return cooling water dissociate and accumulate in the space above the pit, mixing with the air and causing If the mixed gas reaches the explosive limit, there is a risk of ignition and explosion.

Particularly when the dissociated gas component is CO, there is a risk of poisoning.

As a countermeasure against the above-mentioned danger, the present invention dissociates and releases oxygen dissolved in the cooling water by blowing an inert gas (e.g. N2) into the cooling water in the storage pit, and dissociates and releases all of the dissolved sediment in the cooling water. By completely cooling the high-temperature gas, the dissociation and release of oxygen from the cooling water into the Hatane gas is completely reduced, and when the circulating cooling water containing all dissolved 00 etc. contained in the high-temperature gas is returned to the storage bit, the above-mentioned By blowing inert gas,
All of the dissolved gas components such as CO are replaced with the inert gas and released from the cooling water, and the released gas components are released into the atmosphere or into a safe environment such as processing equipment as an inert gas mixture. This is a method of dissociating dissolved components during cooling, and the suction of the present invention is for cleaning flammable gases or for blowing inert gas such as N2 into the storage bit circle where all the circulating water for side cooling is stored. In the present invention, fij% of dissolved components in the cooling water are separated and removed, and atmospheric components are completely prevented from entering the water, and all gas components dissociated from the returned cooling water are made into a mixture with the inert gas. The reason why the 'bk inert gas was selected as a preferable example is as follows.

Conventionally, the methods for completely removing dissolved components in water, especially oxygen, include chemical treatment methods by adding sodium sulfite, hydrazine, etc. in boiler feed water treatment, and mechanical deoxidation methods such as deoxidation methods using deaerators or nitrogen gas. There is a method to deal with it.

In addition, room-temperature deoxidation methods that can be considered for application to the present BFG (blast furnace gas) line include methods using iron scraps, room-temperature vacuum deaeration, addition of aggregates, and deoxidation methods using nitrogen gas.

The deoxidation method using nitrogen gas, which is used in the above cases, utilizes the concept of Henry's law.

For substances with low solubility such as CO2, 02, and N2, C
! =H-P (0: gas concentration in water, P: partial pressure of absorbed component, H: solubility coefficient), which is known as Henry's law. That is, the solubility of a gas in a liquid is proportional to the partial pressure of that gas on the liquid surface, and decreases as the temperature of the liquid increases. Therefore, when pure nitrogen gas is brought into contact with water containing dissolved oxygen, the oxygen partial pressure of pure nitrogen is zero, so according to Henry's law, the dissolved oxygen in the water will migrate into pure nitrogen gas, and the dissolved oxygen will be Decrease. This n- is the principle of the deoxygenation method using nitrogen.

This deoxidation method using nitrogen gas makes it easy to obtain pure nitrogen.
The reason why N2 is preferred as an inert gas is that it is the most economical and satisfactory method in terms of performance in steel mills and the like.

Next, an embodiment of the present invention will be described in detail using the flow sheet shown in FIG.

This example is an example in which the method of the present invention is applied to cooling blast furnace gas BFG containing a large amount of CO, and is an example in which the method is applied to a system in which BFG is cooled in a gas cooler 3 and then sent to the next process. High temperature BFG is 5,000~100,000 from BFG line 1
It is fed into the gas cooler 3 from the lower part at a passing rate of 0 N'/H. The BFG fed f' has a capacity of 22
The circulating water is sucked up by the circulating water pump 9 from the circulating water bit 5 at 0 m' and sprayed from the cooling water nozzle 4 provided in the gas cooler 3 (150"/H) to cool the gas cooling. It is sent to the next process from the upper main pipe 2 of the vessel.

The line 11' communicating with the cooling water storage bit 5 was filled with makeup water, and the amount of makeup water was 75 rrl/H. Also, 10
is an overflow line that opens into the storage bit 5, and its main purpose is to maintain the temperature balance of the cooling water.

With only the above configuration, the BFG comes into contact with the cooling water in the gas cooler and its temperature drops, causing the cobalt in the BP and G to drop.

Co2. Each component such as N2 is replaced with 02 etc. in the cooling water.

Dissolved components (02, etc.) in the cooling water mix into the BFG after cooling, so the concentration of 02 in the BFG increases and is likely to reach the explosive limit.

On the other hand, in the cooling water storage bit 5, CO and the like mixed with the returned cooling water are released from the cooling water, and there is a possibility that the CO and the like that have settled in the returning cooling water will reach the explosion limit in the upper part of the storage bit 5 and around the bit.

In order to solve two problems: the risk of reaching the explosion limit due to the increase in the concentration of 02 in the BFG after cooling, and the risk of reaching the explosion limit due to Co K around the storage bit, A gas blowing pipe, in this embodiment a nitrogen gas blowing pipe 6, is immersed in the storage bit 5, and the storage bit 5 is
was covered with a lid 12 having an outlet 8. Then, the blowing pipe 6VCN2 is supplied at 0.1'/H from the N2 line 7, and is blown into the cooling water to dissociate 02 from the cooling water in the storage bit. It was the atmosphere. Due to the dissociation of 02 in the cooling water, B
The increase in the concentration of 02 in the FG is virtually eliminated, and since the upper space of the storage bit has an atmosphere mainly composed of N2, dissolution of atmospheric components (02) into the cooling water can be prevented, and the atmosphere around the storage bit can be prevented. The problem of explosion risk was also resolved. Furthermore, when releasing 02, CO, etc. from the outlet 8 as a mixture with N2 to a safe place, there is no possibility of an explosion.

Therefore, the present invention prevents the dissolution of 02 into the cooling water, the resulting increase in the contamination of 02, etc. into the gas, and the unsafe release of 00, etc. into the atmosphere, thereby preventing explosion accidents. It has great effects in terms of the environment and the prevention of factory disasters.

[Brief explanation of the drawing]

FIG. 1 shows a flow sheet of an embodiment of the present invention. 1... BFG line, 2... Cooler upper main pipe, 3...
...Gas cooler, 4...-cooling water nozzle, 5...cooling water storage bit, 6...nitrogen blowing pipe, 7...N2 line, 8...discharge port, 9...circulation Water Bonzo, 10...
・Overflow line, 11... Makeup water line, 1
2... Lid agent Patent attorney Masa Akizawa Mitsugai 2 people

Claims (1)

[Claims] (1) By blowing inert gas such as N2 into the storage pit where circulating water for cleaning flammable gas or cooling is stored, dissolved components in the cooling water are dissociated and removed, and atmospheric components are prevented from entering the water. A method for dissociating dissolved components in cooling water for treating flammable gases, characterized in that the gas components dissociated from the returned cooling water are released as a mixture with the inert gas to a safe place.