JPS5861818A - Wet type treatment for waste gas - Google Patents

Abstract

PURPOSE:To improve absorption efficiency and to make the size of an absorption tower smaller and the number of pumps less by supplying a fresh absorbent through an absorbent controlling tank into the initial or final stage of an absorption zone directly. CONSTITUTION:An absorbent for replenishing is replenished into an absorbent controlling tank 1. A supply pipe 10 to the final stage is closed, a supply pipe 9 to the initial stage is opened, and an absorging source soln. by the fresh absorbent is sprayed from the tank 1 concentrically to the initial stage of an absorbing zone 6 through the pipe 9 by the 1st spray pump 4. The pipe 9 to the initial stage is closed, the pipe 10 to final stage is closed and the absorbent is sprayed concentrically to the final stage of the zone 6 through the pipe 10. Or the absorbent is sprayed concentrically to the initial stage and the final stage. In either cases, the soln. in a storage tank 3 for circulating liquid is sprayed to the intermediate stages of the zone 6 by the 2nd pump 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wet exhaust gas treatment method, and in particular, to treat harmful gases such as sulfur oxides, hydrogen sulfide, hydrogen chloride, chlorine, and hydrogen fluoride in flue gas. The present invention relates to a method of absorbing and removing substances using an absorbent suitable for the purpose, such as carbonated searam, hydroxylated searum, sodium hydroxide, etc.

In the conventional exhaust gas treatment method of this kind, for example, as shown in Fig. 1, the method of introducing the absorbent A into the process is to directly introduce it into the circulating liquid storage tank C utilizing the lower part of the absorption tower. Since a part of the absorption rate of the absorbent is wasted on the nuclide C, there is a drawback that the absorption energy τ of the absorbent is not utilized to the maximum extent possible.

Therefore, the absorption zone d becomes large, that is, the absorption tower becomes tall and large, and the number of pumps e also increases, which increases both the equipment cost and the operating cost, which is not desirable. Note that the arrow f indicates the inflow of untreated gas, and the arrow g indicates the outflow of treated gas.

The present invention does not simply replenish the circulating liquid reservoir with the absorbent, but supplies it to the absorbent adjustment tank, and intensively sprays the absorbent solution to a specific part of the absorption zone. The purpose is to provide a wet exhaust gas treatment method that can reduce equipment costs and operating costs by reducing the size of the absorption tower, reducing the number of pumps, and reducing the amount of absorbent used for the treated gas. That is.

Therefore, in the exhaust gas treatment method of the present invention, the absorbent solution made of the fresh absorbent replenished in the absorbent adjustment tank is applied to at least one of the first stage and the last stage of the absorption zone in the absorption tower.
It is characterized by concentrated supply to

Embodiments of the present invention will be described below with reference to FIGS. 2 to 6.

In Figure 2, 1 is an absorbent adjustment tank, 2 is an absorption tower,
3 is a circulating liquid storage tank, 4 is a first absorption spray pump, 5 is a second absorption spray pump, 6 is an absorption zone in the absorption tower 2, 7 is an inflow arrow for untreated gas, and 8 is an outflow for treated gas. Arrows 9 are an absorbent solution supply pipe from the pump 4 to the first stage of the absorption zone 6, 10 is an absorbent solution supply pipe to the last stage, and 11 is an arrow indicating replenishment of replenishing absorbent.

That is, as shown by an arrow 11, the absorbent for replenishment is supplied to the absorbent adjustment tank 1. Then, the supply pipe 10 to the final stage is closed, the supply pipe 9 to the first stage is opened, and the first spray pump 4 supplies the absorbent solution with the fresh absorbent from the tank 1 to the absorption zone through the supply pipe 9. Spray concentratedly on the first stage. Alternatively, the supply pipe 9 to the first stage is closed, the supply pipe 10 to the final stage is opened, and the spray is concentrated from the supply pipe 10 to the last stage of the absorption zone 6. Alternatively, both the pipes 9 and 10 are detected and sprayed intensively to the first and last stages of the absorption zone B. of course,
In either case, the second absorption spray pump 5 sprays the solution in the circulating fluid reservoir 3 onto the intermediate stage of the absorption zone 6 .

In this way, since the fresh stock solution is intensively supplied to a specific portion of the absorption zone 6, the absorption efficiency within the absorption zone 6 is improved.

Now, if we express the absorption operation from the lower part of the absorption tower 2 to the upper part of the tower in terms of the relationship between the absorbed gas concentration and P On the other hand, the relationship of the present invention is represented by a solid line.

However, Figures 3 to 5 are subject to the following conditions. That is, in both the conventional method and the process of the present invention, the ratio of the absorption solution to the process gas is the same, the absorption space is the same, and the acidic gas is absorbed by the alkali. Regarding the present invention to be compared, FIG. 3 shows the case where only the absorption source solution is sprayed from the first stage to the first stage of the absorption tower 2 by the first absorption spray pump 4 shown in FIG. 2, and the case where only the last stage is sprayed is shown in FIG. Fig. 4 shows the case where only the first stage and final stage are sprayed - Fig. 5 shows the case.

As seen in FIGS. 3 to 5, the concentration of the absorbed gas at the outlet of the absorption tower is lower in all cases in the present invention than in the conventional method.

Note that one of the conditions in the case of FIGS. 6 to 5 is that an acid gas is absorbed by an alkali, but the same explanation can be applied to the absorption of an alkaline gas by an acid. It is also possible to reverse the gas flow in FIG. 2, i.e., by exchanging arrows 8 and 7 in FIG. , the relationship between absorption operations when the same absorption efficiency as the conventional method is required is shown in FIG. That is, ΩA in FIG. 6 shows the absorption zone of the conventional process, and B shows the absorption zone of the process of the present invention. In the present invention, the absorption zone can be made smaller, and the ratio of the absorbent solution to the process gas can be reduced. Can be made smaller.

In this way, the present invention supplies the absorbent to the absorbent adjustment tank without replenishing the circulating liquid storage tank, and supplies the absorbent solution intensively to at least one of the first stage and the last stage of the absorption zone. The method is to use a fresh absorbent,
comes into direct contact with the flue gas and responds quickly to improve absorption performance. Therefore, the absorption zone can be shortened, making it possible to downsize the absorption tower and reduce the number of pumps, reducing equipment and operating costs. It is possible to reduce □.

Fig. 3 is a comparative illustration of the case where the absorbent solution is supplied only to the first stage as shown in Fig. 2 and the conventional method, and Fig. 4 is a diagram showing a case in which the absorption solution is supplied only to the final stage in the same way. FIG. 5 is a similar explanatory diagram for the case of supplying to the first stage and final stage, and FIG. 6 is a comparative explanatory diagram of the size of the absorption zone of the present invention and the conventional method. .

1... Absorbent adjustment tank, 2... Absorption tower, 3...
Circulating fluid reservoir, 4...first absorption spray bong, 5...
- Second absorption spray pump, 6... absorption zone.

Patent applicant: Ishikawajima Harima Heavy Industries Co., Ltd. 5th sheep

Claims (1)

[Claims] 1. A wet exhaust gas treatment method, characterized in that an absorbent solution made of fresh absorbent replenished in an absorbent adjustment tank is intensively supplied to at least one of the first stage and the last stage of an absorption zone in an absorption tower.