JP2011026159A - Sulfuric acid production facility - Google Patents

Abstract

It is possible to prevent the production of waste sulfuric acid while raising the temperature of a converter.
SOLUTION: Moisture in a source gas is absorbed and removed by sulfuric acid, and a drying tower 1 for discharging the gas from which moisture has been removed is introduced. A gas discharged from the drying tower 1 is introduced, and SO ₂ contained in the gas is converted into SO ₂ . ₃ converted into a converter 2 for discharging gas containing SO _3, absorption tower for discharging the SO ₃ was recovered off-gas recovered SO ₃ contained in the gas introduced gas discharged from the converter 2 3 is provided with an introduction line L100 for introducing the off-gas discharged from the absorption tower 3 into the drying tower 1, so that water is removed in the drying tower 1 and then passed through the converter 2. The off-gas discharged from the absorption tower 3 is reintroduced into the drying tower 1 through the introduction line L100, and the gas introduced into the drying tower 1 while raising the temperature of the converter 2 is used as a gas from which moisture has been removed. 1 concentration of sulfuric acid decreases By suppressing the door, to prevent the waste sulfuric acid is produced.
[Selection] Figure 1

Description

  The present invention relates to a sulfuric acid production facility.

Conventionally, the absorption tower to produce a converter to convert the SO ₂ in SO ₂ containing gas to SO _3, the higher concentrations of sulfuric acid by absorption of SO ₃ produced by the conversion of SO ₂ to the circulation of concentrated sulfuric acid, There is known a sulfuric acid production facility comprising (see, for example, Patent Document 1). In such a sulfuric acid production facility, a drying tower is widely disposed in the upstream of the converter to absorb and remove moisture in the SO ₂ -containing gas introduced into the converter by circulating sulfuric acid. ing.

JP 2002-53311 A

The sulfuric acid production facility as described above is, for example, at the time of start-up, and when the temperature of the converter is low, the converter needs to be heated to a predetermined temperature at which SO ₂ can be converted to SO ₃ . In such a case, the temperature of the converter is raised while passing a gas such as SO ₂ -containing gas or the atmosphere through the drying tower, the converter, and the absorption tower. In the meantime, since a gas such as SO ₂ containing gas or air is continuously introduced into the drying tower, the water in these gases is absorbed by the circulating sulfuric acid, and the concentration of the circulating sulfuric acid is greatly reduced. And since the circulating sulfuric acid whose density | concentration fell significantly becomes a cause of corrosion of a drying tower, it must be discharged | emitted as waste sulfuric acid from a drying tower. Thus, in the sulfuric acid production facility as described above, there is a problem that a large amount of waste sulfuric acid having a greatly reduced concentration is produced while the converter is heated.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a sulfuric acid production facility capable of preventing the production of waste sulfuric acid while raising the temperature of the converter. .

In view of this, the sulfuric acid production facility according to the present invention introduces a drying tower that absorbs and removes moisture in the gas containing SO ₂ by sulfuric acid and discharges the gas from which moisture has been removed, and introduces the gas discharged from the drying tower. While converting the SO ₂ therein to SO ₃ and discharging the gas containing SO ₃ , the gas discharged from the converter is introduced, and the SO ₃ in the gas is absorbed into sulfuric acid and recovered. And a sulfuric acid production facility comprising an absorption tower for discharging off-gas after the recovery of SO ₃ , and an introduction line for introducing the off-gas discharged from the absorption tower to the drying tower when the temperature of the converter is increased It is characterized by.

  According to such a sulfuric acid production facility, off-gas discharged from the absorption tower through the converter after moisture is removed in the drying tower can be reintroduced into the drying tower through the introduction line. According to this, since the gas sequentially introduced into the drying tower while raising the temperature of the converter is the gas from which moisture has been removed, the concentration of sulfuric acid in the drying tower decreases while the temperature of the converter is raised. Is suppressed. Therefore, it is prevented that waste sulfuric acid is produced while the converter is heated.

  Thus, according to the present invention, it is possible to prevent the production of waste sulfuric acid while raising the temperature of the converter.

It is a block diagram which shows the sulfuric acid manufacturing equipment which concerns on this embodiment.

  A preferred embodiment of the sulfuric acid production facility according to the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a sulfuric acid production facility according to this embodiment.

The sulfuric acid production facility 10 shown in FIG. 1 produces sulfuric acid from a raw material gas containing SO ₂ . Here, the raw material gas in the present embodiment is, for example, high concentration SO ₂ generated when regenerating the carbonaceous adsorbent that has adsorbed SO ₂ in the exhaust gas in an exhaust gas treatment facility using a carbonaceous adsorbent such as activated carbon. Contains gas.

The sulfuric acid production facility 10 introduces the gas discharged from the drying tower 1 into which the moisture removed from the raw material gas is absorbed by sulfuric acid and removed, and the gas discharged from the drying tower 1 is introduced into the SO ₂ contained in this gas. the a converter 2 and converted to SO ₃ for discharging the gas containing SO _3, converter 2 by introducing a gas discharged from the high concentration of sulfuric acid SO ₃ contained in the gas is recovered by absorption in sulfuric acid And an absorption tower 3 for discharging the gas from which SO ₃ is recovered as off-gas, and a gas line L1 for introducing the raw material gas into the drying tower 1 and a gas discharged from the drying tower 1 are converted. A gas line L2 for transfer to the converter 2, a gas line L3 once branched from the gas line L2 and joined again to the gas line L2, and a part of the gas discharged from the converter 2 is transferred to the absorption tower 3 For gas line 4 and a gas line L5 for circulating the remainder of the gas discharged from the converter 2 between the converter 2 and a heat exchanger 5 described later, and off-gas discharged from the absorption tower 3 to the outside. An off-gas line L6, and a gas line L2 and a gas line L4 disposed between the gas from the drying tower 1 toward the converter 2 and the gas from the converter 2 toward the absorption tower 3 Heat is generated between the heat exchanger 4 that performs heat exchange, the gas that is disposed in the gas line L2 and the gas line L5 and that travels from the drying tower 1 to the converter 2, and the gas that circulates through the converter 2 and the heat exchanger 5. A heat exchanger 5 for exchanging, a starter furnace 6 for heating the gas introduced and introduced in the gas line L3, and a gas flow from the drying tower 1 to the converter 2 or from the converter 2 to the absorption tower 3 Arranged in gas line L2 to form gas flow etc. Blower B.

  The drying tower 1 was sprayed from a sulfuric acid spray nozzle 1a for spraying sulfuric acid downward and bringing the source gas and sulfuric acid into contact with the raw material gas introduced from the bottom through the gas line L1 and facing upward, and the sulfuric acid spray nozzle 1a. It has a packed bed 1b for increasing the contact area between the sulfuric acid and the raw material gas. With this structure, the water in the raw material gas is absorbed and removed by sulfuric acid, and the gas from which the water has been removed is discharged from the top of the tower. To do.

The converter 2 is configured by laminating a plurality of catalyst layers filled with an oxidation catalyst. By passing a gas introduced from the upper part of the gas line L2 through these catalyst layers, the converter 2 was oxidized SO ₂ converted to SO _3, it is discharged from the bottom of the gas containing SO _3.

The absorption tower 3 is composed of a sulfuric acid spray nozzle 3a for spraying sulfuric acid downward with respect to the gas introduced from the bottom through the gas line L4 and bringing the gas into contact with sulfuric acid, and sulfuric acid sprayed from the sulfuric acid spray nozzle 3a. has a filling layer 3b to increase the contact area with the gas, the SO ₃ in the gas to be introduced by this arrangement to produce a high concentration of sulfuric acid is recovered by absorption in sulfuric acid, SO ₃ The recovered gas is discharged from the top of the tower as off-gas.

  The starter furnace 6 has a heating device for heating the gas, and when the temperature of the converter 2 is increased, a part of the gas discharged from the drying tower 1 is introduced, and the introduced gas is heated by the heating device. , Exhaust the heated gas.

  Such a sulfuric acid production facility 10 further includes a plurality of sulfuric acid lines for transferring sulfuric acid. Specifically, a sulfuric acid line L7 for supplying a part of sulfuric acid sprayed from the sulfuric acid spray nozzle 1a, passing through the packed bed 1b, falling and stored in the bottom of the drying tower 1 to the sulfuric acid spray nozzle 1a again, Similarly, a sulfuric acid line L8 for transferring a part of the sulfuric acid stored at the bottom of the drying tower 1 to the absorption tower 3 and the sulfuric acid spray nozzle 3a sprayed from the packed bed 3b and dropped and dropped. A sulfuric acid line L9 for supplying a part of sulfuric acid stored at the bottom to the sulfuric acid spray nozzle 3a again, and a part for transferring a part of sulfuric acid stored at the bottom of the absorption tower 3 to the drying tower 1 in the same manner. Similarly, a sulfuric acid line L10 and a sulfuric acid line L11 for conveying a part of the sulfuric acid stored at the bottom of the absorption tower 3 to the outside as product sulfuric acid are provided. The sulfuric acid lines L7 and L8 and the sulfuric acid lines L9 to L11 are respectively provided with a pump P1 and a pump P2 so as to form a flow of sulfuric acid in each line.

  Here, in addition to the above configuration, the sulfuric acid production facility 10 of the present embodiment is particularly for introducing the off-gas connected to the off-gas line L6 and the gas line L1 and discharged from the absorption tower 3 into the drying tower 1. An introduction line L100 is provided. This introduction line L100 is used when the converter 2 is heated. The introduction line L100 is provided with a valve V1, and the gas line L1 is provided with a valve V2.

According to the sulfuric acid production facility 10 configured as described above, during normal operation in which the temperature of the converter ₂ is at a temperature (for example, about 400 ° C.) at which SO ₂ can be converted to SO ₃ , the valve V1 is closed. At the same time, the valve V2 is opened, new raw material gas is sequentially introduced into the drying tower 1 from the gas line L1, and the raw material gas introduced into the drying tower 1 is removed by moisture absorbed by sulfuric acid in the drying tower 1. And heated by the heat exchanger 4 and the heat exchanger 5, SO ₂ is converted to SO ₃ by the converter 2, and after heating the heat exchanger 4 and the heat exchanger 5, the SO ₃ is sulfuric acid by the absorption tower 3. It is absorbed and recovered and released to the outside as off-gas. Through these processes, high-concentration sulfuric acid is produced in the absorption tower 3. Further, in order to keep the concentration of sulfuric acid in the drying tower 1 constant, sulfuric acid that has been absorbed by the drying tower 1 and reduced in concentration is sent to the absorption tower 3 by the sulfuric acid line L8, and SO ₃ is absorbed by the absorption tower 3. Then, a part of the sulfuric acid whose concentration is increased is introduced into the drying tower 1 through the sulfuric acid line L10.

Here, according to the sulfuric acid production facility 10, in particular, when the temperature of the converter 2 does not reach a temperature at which the SO ₂ can be converted into SO ₃ at the time of starting, the drying tower 1 from the gas line L1. A predetermined amount of raw material gas is introduced into the drying tower 1 for raising the temperature, and the raw material gas introduced into the drying tower 1 is partially introduced into the starter furnace 6 after moisture is removed by the drying tower 1. Then, it is heated and merged with the gas passed through the heat exchangers 4 and 5, passes through the converter 2, passes through the heat exchangers 4 and 5, is introduced into the absorption tower 3, and is discharged to the off gas line L 6.

  At this time, since the valve V1 is closed and the valve V2 is opened, the offgas discharged from the absorption tower 3 is again introduced into the drying tower 1 through the introduction line L100 connected to the offgas line L6. The

That is, according to the sulfuric acid production facility 10, when the converter 2 is heated at the time of startup, a predetermined amount of the raw material gas introduced into the drying tower 1 for raising the temperature is supplied to the starter furnace 6 (or the heat exchanger 4). 5), the converter 2, the heat exchangers 4 and 5, the absorption tower 3, the introduction line L100, and the drying tower 1 are circulated in this order and heated each time passing through the starter furnace 6 (or the heat exchangers 4 and 5). The heated gas is repeatedly passed through the converter 2 to raise the temperature of the converter 2. When the temperature of the converter 2 reaches a temperature at which SO ₂ can be converted to SO ₃ , the valve V1 is closed and the valve V2 is opened, and the process proceeds to the normal operation.

  As described above, according to the sulfuric acid production facility 10 of the present embodiment, when the temperature of the converter 2 is increased, the off-gas discharged from the absorption tower 3 through the converter 2 after moisture is removed by the drying tower 1 is reduced. The gas introduced into the drying tower 1 again by the introduction line L100 and sequentially introduced into the drying tower 1 while raising the temperature of the converter 2 becomes a gas from which moisture has been removed, so that the temperature of the converter 2 is raised. Further, the sulfuric acid concentration in the drying tower 1 is suppressed from decreasing. Therefore, it is prevented that waste sulfuric acid is produced while the converter 2 is heated.

A gas line L12 for introducing air to the drying tower 1 is connected to the gas line L1, and the air introduced from the gas line L12 to the drying tower 1 via the gas line L1 is SO ₂ . This is supplied to the converter 2 as a supply source of oxygen necessary for the conversion to SO ₃ .

  In the above embodiment, when the temperature of the converter 2 is raised, a predetermined amount of source gas is introduced and circulated from the gas line L1 for raising the temperature. Instead of this source gas, the gas line L12 is used. A configuration may be adopted in which the atmosphere is introduced and circulated, or another gas may be introduced from the starter furnace 6 and circulated.

  Furthermore, the present invention can also be applied during the temperature rise of the converter 2 other than at the time of startup.

DESCRIPTION OF SYMBOLS 1 ... Drying tower, 1a, 3a ... Sulfuric acid spray nozzle, 1b, 3b ... Packing bed, 2 ... Converter, 3 ... Absorption tower, 4,5 ... Heat exchanger, 6 ... Start-up furnace, 10 ... Sulfuric acid production equipment, L1 L5, L12 ... gas line, L6 ... off-gas line, L7-L11 ... sulfuric acid line, L100 ... introduction line.

Claims (1)

Moisture in the gas containing SO ₂ is absorbed by sulfuric acid and removed, and a drying tower that discharges the gas from which moisture has been removed is introduced, and the gas discharged from the drying tower is introduced to convert SO ₂ in the gas into SO ₃ . Then, a converter that discharges a gas containing SO ₃ and a gas discharged from the converter are introduced and SO ₃ in the gas is absorbed and recovered by sulfuric acid, while this SO ₃ is recovered. In a sulfuric acid production facility comprising an absorption tower that discharges off-gas later,
A sulfuric acid production facility comprising an introduction line for introducing the off-gas discharged from the absorption tower into the drying tower when the converter is heated.

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