JPH0369568B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wet flue gas desulfurization system, and more particularly to a wet flue gas desulfurization system that uses an absorption tower to absorb sulfur dioxide (SO ₂ ) and remove dust.

As shown in Fig. 1, conventional wet flue gas desulfurization equipment includes a cooling and dust removal tower (hereinafter referred to as
The dust removal tower 6 is composed of a sulfur dioxide absorption tower 20 (hereinafter simply referred to as an absorption tower) connected to the dust removal tower 6 via a communication duct 18. The exhaust gas 2 from the boiler etc. passes through the boiler flue 4,
It is introduced into the dust removal tower 6, where it is circulated from the dust removal tower circulation tank 14 via the pump 12 and the line 8, and comes into contact with the circulating water sprayed from the top of the tower, where it is cooled and removes the dust and dust in the flue gas. Impurities such as hydrogen chloride (HCl) and hydrogen fluoride (HF) are removed. This gas is then sent via a connecting flue 4 to an absorption tower 20 where it is pumped from the bottom by a pump 24 through a line 28 to the top of the tower where it is mixed with an absorbent liquid, such as limestone slurry, which is sprayed into the tower. Upon contact, SO ₂ in the exhaust gas is absorbed and removed, and by-products such as CaSO ₂ and CaSO ₄ (gypsum) are generated. Clean exhaust gas 32 from which SO ₂ has been removed is discharged from the flue 30. In addition, 10 is a circulating water extraction piping, 13 is a water piping for cooling and dust removal, 22 is an absorption liquid supply piping, and 26 is an absorption liquid extraction piping.

As mentioned above, in conventional wet flue gas desulfurization equipment,
It was common practice to separate the dust removal tower 6 and the absorption tower 20 so that gas cooling, dust removal, and SO ₂ absorption and removal were performed in separate towers.

However, such a device requires two towers, which not only increases the equipment cost but also increases the installation space.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to perform exhaust gas cooling, dust removal, and SO ₂ absorption and removal in one tower, and to provide a system in which the liquid used for cooling and dust removal is an SO ₂ absorption liquid. An object of the present invention is to provide a dust separation type wet flue gas desulfurization device that prevents mixing.

The present invention consists of a tower body having an inlet duct for exhaust gas containing SO ₂ and an outlet duct for treated gas, and a cooling and dust removal liquid (hereinafter referred to as cooling liquid) provided upstream of the exhaust gas entering the tower body. ), a cooling liquid receiving container provided directly below the spray nozzle, and a cooling liquid circulation means for once storing the cooling liquid in the receiving container in a tank and then circulating it to the spray nozzle by a pump; A spray nozzle for the SO ₂ absorption liquid is provided on the downstream side of the exhaust gas that has entered the tower body, a receiving container for the absorption liquid is provided directly below the spray nozzle, and the absorption liquid that has entered the receiving container is temporarily stored in a tank. After that, the absorbent liquid circulating means is configured to circulate the absorbent liquid to the spray nozzle using a pump.

The present invention cools exhaust gas and removes dust in an absorption tower.
Although SO ₂ absorption is performed at the same time, water is usually used for cooling and dust removal, and the waste liquid after washing is collected in a container and stored in a tank for circulation and use. ₂ Regarding the absorption liquid used for absorption and removal, after absorbing SO ₂ , the absorption liquid is collected in another container and stored in the absorption tower tank for circulation and use. In this way, by installing separate containers under each liquid to prevent the liquids from mixing within the tower, and by separating and collecting each liquid in separate tanks, one tower can be used. It can have the functions of both dust removal and absorption.

The above-mentioned absorbing liquid or cooling liquid receiving container may be one that can catch the liquid dripping from above and prevent it from falling downward, but there is a container directly below the spray nozzle for these liquids that has a large resistance to gas flow from below. It is arranged so that it does not become . A suitable example is
One example is one in which trough-shaped containers are provided in multiple stages, as shown in FIG. 3, which will be described later.

In addition, the tank that collects and temporarily stores the liquid received in the container is used to collect the absorbed liquid, which is handled in large quantities, into the lower tank of the absorption tower, and to store the liquid, which contains dust, which is handled in small quantities, in a separate tank. Although it is advantageous to collect the waste in the lower part of the absorption tower, it is also possible to partition the tank at the bottom of the absorption tower and collect the waste in consideration of the amount to be handled.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is an explanatory diagram showing the configuration of a cooling and dust removal/absorption tower of a wet denitrification apparatus showing an embodiment of the present invention. This device has an inlet duct 4 for exhaust gas 2 at the bottom of the column and an outlet duct 3 for process gas 32 at the top of the column.
0, an absorption liquid circulation tank 34 provided integrally in the lower part of the column main body, an absorption liquid spray nozzle 40 provided in the upper part of the column, and an absorption liquid stored in the tank 34. A piping system 28 that circulates the absorption liquid to the absorption liquid spray nozzle 40 via the pump 24, a receiving container 44 that is provided below the spray nozzle 40 and receives the absorption liquid sprayed from the spray nozzle, and a receiving container 44 that circulates the absorption liquid in the receiving container 44. a recovery duct 46 that flows down to the tank 34;
A coolant spray nozzle 36 is provided on the upstream side of the exhaust gas introduced from the exhaust gas inlet duct 4 and below the absorption liquid receiving container 44, and a coolant spray nozzle 36 is provided below the coolant spray nozzle 36 to spray the coolant sprayed from the spray nozzle. A receiving container 48 for receiving and the receiving container 48
Coolant circulation tank 54 that temporarily stores the coolant of
and a piping system 5 for circulating the coolant in the tank 54 to the coolant spray nozzle 36 by a pump 52.
It is mainly composed of 0 and 0. In addition, 22 is an absorption liquid (limestone slurry) supply pipe, 26 is its extraction pipe, 42 is a demister provided at the top of the tower, 4
Reference numeral 5 indicates a cooling liquid supply pipe, and reference numeral 56 indicates an extraction pipe thereof.

FIG. 3 shows a cross-sectional view of the absorption liquid or cooling liquid receiving vessel (44 or 48) shown in FIG. 58B arranged in two stages in a staggered manner. The interval C between the upper troughs is arranged to be narrower than the opening width D of the lower trough, so that even if a droplet 60 falling from above passes between the upper troughs 58A, it is received by the lower trough 58B. It's getting old. Further, the interval between the upper trough 58A and the lower trough 58B is appropriately determined so that the flow path resistance of the gas 62 does not become excessive and the droplets 60 do not fall out of the trough by mistake. The droplets falling into the troughs 58A and 58B flow in the direction of the inclination of the troughs, ie, in the right-hand direction of the receiving container 44 or 48 in FIG. 2, and are collected in the tank 34 or 54 as described above.

In the apparatus configured as described above, the exhaust gas 2 enters the absorption tower 38 through the duct 4, and is first cooled and dusted by droplets of cooling liquid sprayed from the upstream spray nozzle 36; Receiving container 48
The object is caught by the object and recovered without falling downward. This liquid is collected in a separate tank 54, and pumped by a pump 52 to the spray nozzle 3.
6, circulated and used. When a receiving container with such a combination of troughs is used, the downward drop of the liquid can be suppressed to 5% or less.

In this way, the cooled and dust-removed exhaust gas is then absorbed and removed by droplets sprayed from the SO ₂ absorption spray nozzle ₃₀ at the top of the tower, and then the droplets are transferred to the receiving container 44. The waste is collected through the recovery duct 46 and recovered into the tank section 34 at the bottom of the tower. This recovered liquid is returned to the upper part of the tower by the absorption tower circulation pump 24, and is circulated and used.

The exhaust gas from which SO ₂ has been removed is sent to the demister 40 at the top of the tower.
After removing the scattered mist, it is discharged from the flue 30 as clean gas 32. The absorption liquid is supplied from a pipe 22, extracted from a pipe 26 according to the amount of SO ₂ absorbed, passes through an oxidation tower (not shown), and gypsum as a by-product is produced and recovered. On the other hand, water for cooling and dust removal is supplied from a pipe 45 and extracted from a pipe 56 depending on the dust concentration in the tank 54.
Processed separately.

In addition, without separating the cooling liquid and absorption liquid,
If they are mixed and collected in the same tank, depending on the amount of dust in the gas at the tower inlet, the dust content in the by-product gypsum will increase, which will only deteriorate the quality of the by-product. However, in the case of exhaust gas containing HCl, HF, etc., such as coal combustion exhaust gas, these acidic components are mixed into the absorption liquid, reducing SO ₂ absorption performance.

According to the present invention, since the functions of cooling, dust removal, and SO ₂ absorption and removal are provided in one tower, the equipment becomes compact, and therefore the installation area is small.
In addition, since cooling, dust removal, and desulfurization are completely separated, impurities such as dust, HCl, and HF in the flue gas do not mix into the absorption liquid, preventing deterioration in the performance of the absorption liquid and preventing by-products. The quality of the gypsum product can be improved. In addition, by providing a receiver for the cooling liquid or absorption liquid in the tower, the dispersibility of the exhaust gas is improved and the gas-liquid contact effect is increased.
The effect of improving the desulfurization rate can also be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a conventional wet flue gas desulfurization device, FIG. 2 is a diagram showing the configuration of a wet flue gas desulfurization device of the present invention, and FIG. 3 is a diagram showing the absorption or cooling system used in the present invention. It is a figure which shows typically the arrangement|positioning of the receiving container of the liquid after dust removal. 2...Exhaust gas, 4...Exhaust gas flue (duct),
22...Absorption liquid supply piping, 24...Absorption pump, 26...Absorption liquid extraction pipe, 34...Absorption liquid tank, 36...Spray nozzle for cooling and dust removal,
40... Spray nozzle for absorption, 42... Demister, 44... Receiving container for absorption, 45... Water for cooling and dust removal, 46... Recovery duct for absorption, 48...
Receiving container for cooling and dust removal, 54...Tank for cooling and dust removal, 56...Piping for extraction after dust removal.

Claims (1)

[Scope of Claims] 1. A tower body having an inlet duct for exhaust gas containing sulfur dioxide (SO ₂ ) and an outlet duct for treated gas, and a cooling liquid spray nozzle provided on the upstream side of the exhaust gas entering the tower body; a cooling liquid receiving container provided directly below the spray nozzle; a cooling liquid circulating means for once storing the cooling liquid in the receiving container in a tank and then circulating it to the spray nozzle by a pump; A spray nozzle for an SO ₂ absorption liquid provided on the downstream side of the exhaust gas, a receiving container for the absorption liquid provided directly below the spray nozzle,
A wet flue gas desulfurization device comprising an absorption liquid circulation means that once stores the absorption liquid in the receiving container in a tank and then circulates the absorption liquid to a spray nozzle using a pump. 2. The wet flue gas desulfurization apparatus according to claim 1, wherein the receiving container is a tray-shaped container arranged in multiple stages in a staggered manner. 3. The wet flue gas desulfurization device according to claim 1 or 2, wherein the cooling liquid is water, and the SO ₂ absorption liquid is limestone slurry. 4. The wet type according to any one of claims 1 to 3, characterized in that the absorption liquid tank is provided integrally at the lower part of the tower main body, and the tank after cooling is arranged outside the tower main body. Flue gas desulfurization equipment.