JPH0342011A - Liquid phase oxidation wet desulfurization equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to absorbing oxidizable substances such as hydrogen sulfide and hydrogen cyanide contained in a gas such as coke oven gas into an absorbing liquid. The present invention relates to a liquid-phase oxidation wet desulfurization system that oxidizes an absorption liquid by blowing air or oxygen into the desulfurization system, and particularly to a desulfurization system suitable for converting an existing gas-phase oxidation system to a liquid-phase oxidation system.

[Conventional technology]

For example, the following types of wet desulfurization equipment for raw materials such as coke oven gas, fuel gas, combustion waste gas, etc. are known.

For example, when a gas phase method is adopted for oxidizing the desulfurization absorption liquid, such as the Fumax-Rodax method, as shown in Fig. 2, the oxidizer absorption liquid 5 circulated from the oxidation tower 7 described later is absorbed. Shower from the top of tower 6, raw coke oven gas l
The oxidized substances such as hydrogen sulfide are absorbed by contact with the liquid in an alternating current and stored in a liquid reservoir 18 (normally 5 to 10 m deep) at the bottom of the absorption tower 6, and then extracted from the liquid reservoir 18 of the absorption tower 6. The unoxidized absorption liquid 3 is extracted by the output pump 17, and the extracted unoxidized absorption liquid 3 is sent to the oxidation tower 7, where the unoxidized absorption liquid 3 is oxidized, and the oxidized absorption liquid is sent to the oxidation tower 7. The structure is such that the liquid is stored in a liquid reservoir 19 (usually at a liquid depth of 5 to LOm) at the bottom of the tank, and is sent to the absorption tower 6 again by an oxidation tower extraction pump 16.

In addition, when a similar wet desulfurization method employs a liquid phase oxidation method such as the Takahax method, the premix method shown in Figure 4 (see Japanese Patent Publication No. 58-49, 590) or the The horizontal gas-liquid mixing method shown in the figure (Japanese Unexamined Patent Publication No. 62-19
2.Refer to No. 490), etc., have been proposed, but basically, as shown in Figure 3, the liquid reservoir 1 at the bottom of the absorption tower 6 is
The unoxidized absorption liquid 3 is extracted from the absorption tower extraction pump 17 from 8, and the extracted unoxidized absorption liquid 3 is sent to the lower part of the oxidation tower 7, and the oxidation air 4 sent by the blower 15
It has a structure in which it is mixed with and oxidized while rising inside the oxidation tower 7. Here, the liquid depth of the oxidation tower 7 is usually higher than the height of the absorption tower 6 (20 to 30 m).

[Problem to be solved by the invention]

However, the gas-phase oxidation method has poor gas-liquid contact efficiency;
There are problems in that a large amount of air is required for oxidation, and the waste gas treatment from the oxidation tower is a heavy burden.Also, the absorption liquid often contains a large amount of solid content, and the shower is performed from the top of the oxidation tower. Solid content may adhere to the internal structures of the tower, such as the spray nozzles, causing a blockage condition and causing a decrease in oxidizing ability. When this attached solid content becomes large and peels off, it clogs the packing in the absorption tower, causing a decrease in absorption efficiency. Therefore, in order to remove these deposits, it becomes necessary to carry out a troublesome open cleaning operation every three years or so.

On the other hand, in the liquid phase oxidation method, the gas-liquid contact efficiency can be increased, but the absorption tower extraction pump 17 and air blower
15. In some cases, an insertion pump 14 or the like with considerably high discharge pressure is required.

By the way, in order to convert a gas phase oxidation type desulfurization equipment to a liquid phase oxidation type desulfurization equipment, it is impossible to use the gas phase oxidation type oxidation tower as it is as an oxidation tower similar to the normal Takahax method. , modification of civil engineering foundations requires modification work comparable to new construction work. In addition, even if the premix method or the horizontal gas-liquid mixing method is an improved method, and there is no need to increase the depth of the liquid for oxidation, the liquid contains a large amount of bubbles, so the oxidation tower is removed. Since this causes pump cavitation and eventually erosion, a degassing zone is required and the oxidation tower needs to be significantly remodeled by increasing the liquid depth. Increasing the liquid depth of the oxidation tower in this manner requires a large absorption tower extraction pump.

Therefore, in order to solve various problems in the gas-phase oxidation type desulfurization equipment, the present inventors changed the gas-phase oxidation type equipment to a liquid-phase oxidation type equipment, and at the same time, the oxidation tower The present invention was completed after various studies were conducted on an apparatus that does not increase the liquid depth and can solve the problems of the conventional liquid phase oxidation apparatus described above.

Therefore, an object of the present invention is to provide an improved liquid-phase oxidation wet desulfurization apparatus that solves the problems in the liquid-phase oxidation method described above. The objective is to provide a device suitable for remodeling.

[Means to solve the problem]

That is, the present invention provides an absorption tower that absorbs and removes oxidized substances in a gas with an absorption liquid, an oxidation tower that oxidizes the oxidized substances by blowing air into the unoxidized absorption liquid from the absorption tower, and an oxidation tower that oxidizes the oxidized substances. A natural communication pipe that communicates and connects the tower and the oxidation tower at the bottom thereof, and a regenerated absorption liquid that is oxidized in the oxidation tower and extracted from the bottom of the tower is circulated to the absorption tower via a degassing tank. This is a liquid phase oxidation wet desulfurization equipment equipped with a circulation path.

In the present invention, the absorbing liquid is one that comes into contact with and absorbs oxidized substances such as hydrogen sulfide and hydrogen cyanide in the gas to be treated.

In addition, the absorption tower is equipped with a spray nozzle for the absorption liquid at the top of the tower, and a liquid reservoir at the bottom of the absorption tower is formed at the bottom of the tower, where the absorption liquid that has been sprayed from the spray nozzle and absorbed the oxidized materials is temporarily collected. A suitable packing material is filled between these dispersion nozzles and the lower liquid reservoir of the absorption tower, and a contact part is provided for making AC contact with the gas introduced from the gas introduction port below. A gas outlet is installed at the top of the tower.

Further, the oxidation tower is provided with a gas-liquid mixing device consisting of a plurality of air blowing nozzles and the like at the bottom of the tower.

The absorption tower and the oxidation tower are connected to each other by natural communication pipes at their lower portions, so that the liquid levels of both are maintained at substantially the same water level.

Therefore, since the liquid level at the bottom of the oxidation tower is low, in order to prevent air from being drawn in and causing cavitation, the suction line of the pump that extracts water from the bottom of the oxidation tower is
Provide a deaeration tank. In other words, in the present invention, the oxidation tower performs the two roles of oxidizing the oxidized material and gas-liquid separation, which were played by the oxidation tower in the conventional liquid phase oxidation method, but the oxidation tower performs only the oxidation of the oxidized material. Gas-liquid separation is carried out in a degassing tank, and by this, an appropriate efficient oxidation method such as horizontal gas-liquid mixing method is adopted to suppress the increase in liquid depth.
It is possible to change the oxidation method by only making minor modifications to the piping, etc. Note that the degassing tank may have any form as long as it has a structure that can prevent cavitation and erosion of the pump.

In addition, there is no need to fry the absorption liquid to the top of the oxidation tower.
By communicating the absorption tower and the oxidation tower through a natural communication pipe, the absorption tower extraction pump can be omitted. moreover,
The liquid depth can be arbitrarily selected by adjusting the liquid level in the oxidation tower or deaeration tank; in other methods, the oxidation treatment time, which is uniquely determined by the absorption liquid circulation amount, must be appropriately selected and determined. is also possible.

〔Example〕

Hereinafter, the apparatus of the present invention will be explained based on the embodiment shown in FIG. 1, and then a test example using the apparatus of the present invention will be explained.

Embodiment FIG. 1 shows the overall flow. The oxidized acquisition liquid 5 circulated from the oxidation tower 7, which will be described later, and the raw coke oven gas l are brought into AC contact at the contact part of the absorption tower 6, and oxidized substances such as hydrogen sulfide in the gas are transferred to the absorption liquid 5. Let it absorb. This absorption liquid 5 is stored as an unoxidized absorption liquid 3 in a lower liquid reservoir 18 of the absorption tower, and the raw coke oven gas 1 is transferred from the top of the absorption tower to the purified coke oven gas 2.
It is sent to the next process as The unoxidized absorption liquid 3 stored in the lower liquid reservoir 18 of the absorption tower naturally flows into the oxidation tower 7 via the natural communication pipe 9. At the bottom of the lower liquid reservoir 19 of the oxidation tower 7, a plurality of gas-liquid mixing devices 10 described in, for example, Japanese Unexamined Patent Publication No. 1988-192490 are installed, and in this gas-liquid mixing device 10, an insertion pump The unoxidized absorption liquid from the blower 14 and the oxidizing air 4 from the blower 15 are efficiently mixed and ejected. Thereby, oxidation is efficiently performed in the oxidation tower.

In this embodiment, the unoxidized absorption liquid from the absorption tower lower reservoir 18 is inserted into the gas-liquid mixing device 10, but the absorption liquid after oxidation from the degassing tank 8 is inserted into the gas-liquid mixing device 10. There is no problem in doing so.

The oxidized absorption liquid 5 is sent from the oxidation tower 7 to the degassing tank 8, where air bubbles are removed from the absorption liquid, and then sent to the absorption tower 6 again by the oxidation tower extraction pump 16.

The air separated in the deaeration tank 8 becomes deaeration waste gas 12,
It is introduced into the waste gas line of the oxidation tower 7, mixed with the waste gas from the oxidation tower 7, and sent to waste gas treatment as the oxidation tower waste gas 13.

The apparatus of the present invention shown in FIG. 1 is a gas-phase oxidation type desulfurization apparatus shown in FIG. Communication pipe 9
A deaeration tank 8 is installed between the lower liquid reservoir 19 of the oxidation tower 7 and the oxidation tower extraction pump 16, and a gas-liquid mixing device is installed at the bottom of the lower liquid reservoir 19 of the oxidation tower 7. 10 was installed and was constructed by making some modifications to the piping.

Test Example A test run was conducted on the liquid phase oxidation wet desulfurization equipment according to the embodiment of the present invention shown in Fig. 1 above, and the amount of waste gas and power consumption were compared with that of the gas phase oxidation method shown in Fig. 2 before modification. It was compared with a desulfurization equipment. The results are shown in Table 1.

Table 1 In addition, in the liquid phase oxidation wet desulfurization equipment according to the embodiment of the present invention, no solid content was observed in the oxidation tower, and the problem of clogging was almost eliminated, eliminating the need for open cleaning, which was performed every three years. It has been found that maintenance and management is possible with regular inspections every six years.

In addition, in the above example, modification of desulfurization equipment from a gas phase oxidation method to a liquefaction-oxidation method was described, but the modification is not limited to this. A similar effect can be obtained when modifying a reaction system through liquid contact, and it can be said that this device is effective not only for modifying existing gas-phase systems to liquid-phase systems, but also for increasing the capacity of liquid-phase systems and installing new ones.

〔Effect of the invention〕

The apparatus of the present invention is an economically superior liquid-phase oxidation wet desulfurization apparatus that can be inexpensively converted from a gas-phase oxidation system to a liquid-phase oxidation system, and can significantly reduce operating costs.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a wet oxidation desulfurization equipment according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing a gas phase oxidation type oxidation desulfurization equipment, and Fig. 3 is an explanatory diagram showing an oxidation desulfurization equipment using the Takahax method. 4 are explanatory diagrams showing improvements in the premix method, and FIG. 5 is an explanatory diagram showing improvements in the horizontal gas-liquid mixing method. Explanation of symbols (1) Raw coke oven gas, (2) Refined coke oven gas, (3) Unoxidized absorption liquid, (4) Oxidizing air,
(5) ... Recovered liquid from plate after oxidation, (6) ... Absorption tower, (7
)... Oxidation tower, (8)... Deaeration tank, (9)...
... Natural communication pipe, (10) ... Gas-liquid mixing device, (1
1) Premix nozzle, (12) Deaeration tank waste gas, (13) Oxidation tower waste gas, (14) Insertion pump, (15) Blower ( 16)...Oxidation tower extraction pump, (17)...Absorption tower extraction pump, (18)...Absorption tower lower liquid reservoir, (19)...Oxidation tower lower liquid storage Figure 2 4 Figure 3 Figure 5

Claims (1)

[Claims] (1) An absorption tower that absorbs and removes oxidized substances in the gas with an absorption liquid, an oxidation tower that oxidizes the oxidized substances by blowing air into the unoxidized absorption liquid from the absorption tower, and these absorption towers and oxidation towers. a natural communication pipe that communicates with the tower at its lower part; and a circulation path that circulates the regenerated absorption liquid oxidized in the oxidation tower and extracted from the bottom of the tower to the absorption tower via a degassing tank. A liquid phase oxidation wet desulfurization equipment characterized by comprising: