JP2001064014A - Ammonia recovering facility for power generation plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively and rapidly recover ammonia contained in wastewater to reuse it by dividing a power generation part into a steam generating/ supplying system and a condensing/water supplying system, and connecting an exhaust gas treating part of the steam generating/supplying system and a demineralizing facility of the condensing/water supplying system to an ammonia rectification plant, respectively. SOLUTION: The exhaust gas treating part 19 of the steam generating/ supplying system 11 and the demineralizing facility 23 of the condensing/water supplying system 12 are connected to the ammonia rectification plant 26 to be newly provided, respectively. The plant 26 is divided into two steps, namely a lowly condensed ammonia rectification part 27 and a highly condensed ammonia rectification part 28 to condense ammonia. The highly condensed ammonia is supplied as a pH adjusting agent to the system 12 and as an NOx concentration controlling agent to the exhaust gas of the part 19 so that the resource as ammonia can be effectively used, the power generation plant can be safely operated by adjusting the pH of the system 12 and air pollution can be prevented by lowering the NOx concentration in the exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia recovery apparatus for a power plant that effectively recovers ammonia contained in condensed water and feedwater.

[0002]

2. Description of the Related Art In a power plant, a large amount of ammonia is used for water quality control based on the pH adjustment of condensed water / supply water and reduction of the concentration of NOx contained in combustion gas.

[0003] For example, in the condensate / water supply system of a steam turbine, the condensate / supply water is used to suppress the corrosion of steel such as piping and equipment.
Although H is adjusted to 9.0 or more, ammonia is used as a PH adjuster.

In the condensate / water supply system, hydrazine or the like is used to remove dissolved oxygen contained in the condensate / water supply.

In a waste heat recovery boiler applied to a boiler or a combined cycle power plant, a denitration device is installed, ammonia is supplied to the denitration device, and the concentration of NOx contained in the combustion gas is kept low.

[0006] As described above, ammonia used for condensed water / supply water as a PH regulator and as a NOx concentration reducing agent for various purposes is discharged to rivers and the like as wastewater after being treated according to each purpose. You. At that time, the ammonia contained in the wastewater is treated by a biological nitrogen removing means that combines a nitrification step and a denitrification step.

Here, the biological nitrogen removing means means that nitrifying bacteria and denitrifying bacteria are combined to finally decompose ammonia contained in wastewater into nitrogen.

A wastewater treatment apparatus incorporating the biological nitrogen removing means has the structure shown in FIG.

For example, wastewater supplied from a condensing / supplying water desalination device or an exhaust heat recovery boiler is collected in a nitrification tank 1 where the PH value is measured by a PH meter 2 and is determined in advance. If it is lower than the PH value, sodium hydroxide from the sodium hydroxide tank 3 is added to adjust the pH.

The nitrification tank 1 is provided with a diffuser 5 from a blower 4.
Oxygen is supplied to the wastewater via the humidifier to promote the growth of nitrifying bacteria in the tank, and the nitrifying bacteria react ammonia contained in the wastewater with nitrogen compounds.

Further, wastewater containing nitrogen compounds is supplied to a denitrification tank 6, where the nitrogen compounds are decomposed into nitrogen by the action of denitrifying bacteria. The denitrification tank 6 is cultivated with denitrifying bacteria that decompose nitrogen compounds into nitrogen. Methanol from the methanol tank 7 is supplied as nutrients of the denitrification bacteria.

The wastewater containing nitrogen from the denitrification tank 6 is once collected in a sedimentation tank 8 and part of the wastewater is blown out into the natural world such as a river, and the remaining nitrifying bacteria and denitrifying bacteria are removed. Is collected in the nitrification tank 1.

[0013]

The conventional biological nitrogen removing means for decomposing the ammonia contained in the condensed water and feed water into nitrogen makes it difficult to cope with the following technical requirements. .

(1) In recent power generation plants, a large unit having a high power generation efficiency is continuously operated every day as a base load, and a small unit having a low power generation efficiency is started and stopped on a daily and weekly basis. It is a general trend to repeat.

In such power plants, which frequently start and stop on a daily or weekly basis, rapid drainage treatment or ammonia treatment in accordance with the load operation of the power plant is required. As described above, it is difficult to realize the biological nitrogen removing means using nitrifying bacteria and denitrifying bacteria in view of the fact that it takes about one month to sufficiently activate the function of each bacteria.

(2) A power plant in which ammonia has been decomposed into nitrogen by means of biological nitrogen removal, has its wastewater collected and
It is not preferable from the viewpoint of effective use of resource energy to blow out the system to the natural world without reuse, and the way of recovery and reuse has been demanded.

The present invention has been made in view of such background art, and provides an ammonia recovery apparatus for a power plant in which ammonia contained in wastewater is effectively and quickly recovered and reused. The purpose is to:

[0018]

In order to achieve the above object, an ammonia recovery apparatus for a power plant according to the present invention comprises a combination of an electric power generation section and an ammonia recovery and regeneration section. In the ammonia recovery apparatus for a power plant, an ammonia rectification plant is provided in the power generation unit.

In order to achieve the above object, an ammonia recovery apparatus for a power plant according to the present invention is provided.
As described in, the power generation unit is divided into a steam generation and supply system and a condensate / water supply system, and ammonia rectification is performed in each of the exhaust gas treatment unit in the steam generation and supply system and the desalination unit in the condensate / water supply system. It is a plant connected.

In order to achieve the above object, the ammonia recovery apparatus for a power plant according to the present invention has the following features.
As described above, the ammonia rectification plant is configured by combining a low-concentration ammonia rectification section and a high-concentration section.

In order to achieve the above object, an ammonia recovery apparatus for a power plant according to the present invention is provided.
As described in the above, the low-concentration ammonia rectifying section is obtained by concentrating ammonia to a concentration of 15%.

In order to achieve the above object, an ammonia recovery apparatus for a power plant according to the present invention is provided.
As described in the above section, the highly concentrated ammonia rectifying section is obtained by concentrating ammonia to a concentration of 99.8%.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ammonia recovery apparatus for a power plant according to the present invention will be described below with reference to the drawings and reference numerals attached to the drawings.

This embodiment has a configuration including an electric power generation unit 9 and an ammonia recovery / regeneration unit 10.

The power generation section 9 is a closed circuit in which two systems of a steam generation / supply system 11 and a condensate / water supply system 12 are combined.

The steam generation / supply system 11 includes a boiler 13, a steam turbine 14, and a generator 15. The steam generation / supply system 11 supplies the fuel from the fuel section 16 and the air from the blower 17 to the boiler 13 to generate combustion gas. The gas is used as a heat source to generate steam, and the steam is supplied to the steam turbine 14 to perform expansion work. The power generated at that time starts the generator 18 to generate electric power.

The steam generation / supply system 11 includes a boiler 13
Is provided with an exhaust gas processing section 19 and a chimney 20, and supplies the combustion gas generated by the boiler 13 to the exhaust gas processing section 19, where the NOx concentration is reduced with ammonia from the ammonia supply section 21, and then, through the chimney 20. Release to the atmosphere.

On the other hand, the condenser / water supply system 12 includes a condenser 22,
Desalination device 23, water supply pump 24, ammonia supply unit 25
The condensed water is condensed by a condenser 22 to be condensed by a condenser 22, and the condensed water is removed by a desalination device 23, and then pressurized by a feed water pump 24. The PH of the pressurized condensed water / water supply is adjusted with ammonia from the ammonia supply unit 25 and returned to the boiler 13.

On the other hand, the ammonia recovery / regeneration unit 10 is provided with an ammonia rectification plant 26 connected to the exhaust gas treatment unit 19 of the steam generation / supply system 11 and the desalination unit 23 of the condensate / water supply system 12, respectively.

The ammonia rectification plant 26 includes a low-concentration ammonia rectification section 27 and a high-concentration ammonia rectification section 28
And a combination.

The low-concentration ammonia rectifying section 27 sequentially arranges the wastewater storage tank 27 along the flow of the wastewater containing ammonia.
a, preheater 30, first rectification column 31, first condenser 3
2. Equipped with a first reflux tank 33 and a first reboiler 34, wastewater containing ammonia supplied from each of the exhaust gas treatment unit 19 and the desalination unit 23 shown in FIG. 1 is temporarily stored in a wastewater storage tank 27a, and during this time, PH from PH adjuster 29
After adjusting the pH with the adjusting agent, the mixture is heated by the preheater 30 and supplied to the first rectification column 31.

The first rectification column 31 has trays arranged inside the height direction, and the supplied wastewater is allowed to fall naturally from each tray to the bottom of the column in order, while being evaporated. Then, the vapor is guided to the top of the tower to gradually concentrate ammonia.

The ammonia vapor concentrated to a concentration of 15% at the top of the tower is condensed in a first condenser 32, and then converted into a 15% -concentration ammonia water and an ammonia mixed water containing other components in a first reflux tank 33. Separation is performed, and the ammonia mixed water containing other components after the separation is returned to the first rectification column 31 again, and 15% ammonia water is supplied to the highly concentrated ammonia rectification section 28.

A part of the ammonia mixed water collected at the bottom of the column is re-evaporated by the first reboiler 34 and returned to the first rectification column 31, and the rest is supplied to the preheater 30 as a heat source. ing.

On the other hand, the highly concentrated ammonia rectifying section 28
A first ammonia water storage tank 35, a second rectification tower 36, a second condenser 37, a second reflux tank 38, a second ammonia water storage tank 39, and a second reboiler are arranged in this order along the flow of the 5% ammonia water. The 15% ammonia water supplied from the first reflux tank 33 of the low-concentration ammonia rectification section 27 is once stored in the first ammonia water storage tank 35 and then supplied to the second rectification tower 36. are doing.

The second rectification column 36 is the same as the first rectification column 31 described above.
As in, trays are arranged along the height direction in the tower,
The steam generated when falling from the tray is collected at the top of the tower and
A 9.8% ammonia vapor concentration is generated.

The ammonia vapor concentrated at the top of the column to a concentration of 99.8% is condensed in a second condenser 37, and then, in a second reflux tank 38, an aqueous ammonia having a concentration of 99.8% and ammonia containing other components The ammonia mixed water containing the other components after the separation is returned to the second rectification column 36 again, and the 99.8% ammonia water is separated into the second mixed water.
It is supplied to the ammonia water storage tank 39.

Further, a part of the ammonia mixed water collected at the bottom of the column is re-evaporated by the second reboiler 34 and returned to the second rectification column 36, and the rest is supplied to the low-concentration ammonia rectification section 27. It is returned to the first rectification column 31 and re-concentrated.

As described above, in the present embodiment, the ammonia rectification plant 26 is provided while being connected to the exhaust gas treatment section 19 of the steam generation / supply system 11 and the desalination device 23 of the condensate / water supply system 12, respectively. Rectification plant 2
6 is divided into two stages, a low-concentration ammonia rectification section 27 and a high-concentration ammonia rectification section 28, to concentrate ammonia, and to use the highly-concentrated ammonia as a PH modifier for condensate and feedwater, and for exhaust gas treatment. Since it is supplied as a NOx concentration inhibitor in the exhaust gas of the part 19, resources can be effectively used, the PH of the condensate water and the supply water can be adjusted, the power plant can be operated stably, and the NOx concentration of the exhaust gas can be improved. Can be reduced to contribute to the prevention of air pollution.

[0040]

As described above, the ammonia recovery apparatus for a power plant according to the present invention is capable of quickly and continuously discharging waste water containing ammonia from a condensate / water supply system or an exhaust gas treatment section of a boiler in an ammonia rectification section. To recover ammonia,
The recovered ammonia was supplied to the condensing / water supply system and the exhaust gas treatment section again in a stable manner, so even small-scale power plants can supply ammonia reliably and quickly in response to load fluctuations. Resources can be quickly and effectively utilized.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing an ammonia recovery device of a power plant according to the present invention.

FIG. 2 is a schematic system diagram of an ammonia rectification plant applied to the ammonia recovery apparatus of the power plant according to the present invention.

FIG. 3 is a schematic system diagram of a wastewater treatment apparatus incorporating a conventional biological nitrogen removing means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nitrification tank 2 PH meter 3 Sodium hydroxide tank 4 Blower 5 Aeration tube 6 Denitrification tank 7 Methanol tank 8 Precipitation tank 9 Power generation unit 10 Ammonia recovery and regeneration unit 11 Steam generation supply system 12 Condensation and water supply system 13 Boiler 14 Steam Turbine 15 Generator 16 Fuel unit 17 Blower 18 Generator 19 Exhaust gas treatment unit 20 Chimney 21 Ammonia supply unit 22 Condenser 23 Desalination unit 24 Feedwater pump 25 Ammonia supply unit 26 Ammonia rectification plant 27 Low concentrated ammonia rectification unit 28 Highly concentrated ammonia rectifying section 29 PH adjusting section 30 Preheater 31 First rectifying tower 32 First condenser 33 First reflux tank 34 First reboiler 35 First ammonia water storage tank 36 Second rectifying tower 37 Second condenser 38 Second reflux tank 39 Second ammonia water storage tank 40 Second reboiler

Claims (5)

[Claims] 1. An ammonia recovery apparatus for a power plant in which an electric power generation section and an ammonia recovery and regeneration section are combined, wherein an ammonia rectification plant is provided in the power generation section. 2. A power generation unit includes: a steam generation / supply system;
2. The ammonia for a power plant according to claim 1, wherein the ammonia separation plant is connected to an exhaust gas treatment section of the steam generation and supply system and a desalination device of the condensate / water supply system. Collection device. 3. The ammonia recovery apparatus for a power plant according to claim 1, wherein the ammonia rectification plant is configured by combining a low-concentration ammonia rectification section and a high-concentration section. 4. The ammonia recovery apparatus for a power plant according to claim 3, wherein the low-concentration ammonia rectification section concentrates ammonia to a concentration of 15%. 5. The high-concentration ammonia rectification section has concentrated ammonia to a concentration of 99.8%.
An ammonia recovery apparatus for a power plant according to claim 1.