TECHNICAL FIELD
[0001] The present disclosure relates to a wet ammonia cleaning equipment and a
fertilizer production plant including the wet ammonia cleaning equipment.
5 BACKGROUND
[0002] A fertilizer production plant for producing a fertilizer by using a methanecontaining gas such as a natural gas includes an ammonia synthesis unit for
producing ammonia from the methane-containing gas, a urea synthesis unit for
producing a urea solution by reacting ammonia with carbon dioxide, and a urea
10 granulation unit for producing granular solid urea from the urea solution. In the urea
granulation unit, a basic gas containing ammonia and urea dust which is, for example,
powder of solid urea is generated. Patent Document 1 describes a wet ammonia
cleaning equipment in which urea dust is removed by gas-liquid contact between
water and a basic gas, and ammonia is removed by gas-liquid contact between the
15 basic gas and an absorbent containing carbon dioxide.
Citation List
Patent Literature
[0003]
20 Patent Document 1: WO2019/234816A
SUMMARY
Technical Problem
[0004] However, as the temperature of a system increases, the solubility of a gas
25 decreases and the concentration of carbon dioxide in an absorbent decreases, causing
a problem that basic gas treatment efficiency decreases. There is a demand for a
3
technique for increasing the concentration of carbon dioxide in the absorbent. In the
wet ammonia cleaning equipment described in Patent Document 1, there is a limit to
the amount of carbon dioxide that can be supplied to the absorbent circulating
through an ammonia scrubber in which gas-liquid contact between the absorbent and
5 the basic gas is performed. In order to further increase the concentration of carbon
dioxide in the absorbent, it is necessary to use a multi-stage fine bubble generator
and to supply more carbon dioxide to the absorbent from the second stage onwards.
[0005] In view of the above, an object of at least one embodiment of the present
disclosure is to provide a wet ammonia cleaning equipment capable of improving
10 basic gas treatment efficiency and a fertilizer production plant including the wet
ammonia cleaning equipment.
Solution to Problem
[0006] In order to achieve the above object, a wet ammonia cleaning equipment
15 according to the present disclosure is a wet ammonia cleaning equipment for treating
a basic gas containing ammonia, including: an ammonia scrubber for bringing the
basic gas into gas-liquid contact with an absorbent containing carbon dioxide; and a
fine bubble generator for producing the absorbent from carbon dioxide and water.
The fine bubble generator includes at least: a first fine bubble generator for producing
20 a first absorbent from carbon dioxide and water; and a second fine bubble generator
for producing the absorbent from carbon dioxide and the first absorbent.
Advantageous Effects
[0007] According to the wet ammonia cleaning equipment of the present disclosure,
25 by absorbing carbon dioxide in each of at least the first fine bubble generator and the
second fine bubble generator, the concentration of carbon dioxide in the absorbent
4
can be increased compared to a case where carbon dioxide is absorbed by one fine
bubble generator. Thus, it is possible to improve basic gas treatment efficiency.
BRIEF DESCRIPTION OF DRAWINGS
5 [0008] FIG. 1 is a schematic view showing the configuration of a wet ammonia
cleaning equipment according to Embodiment 1 of the present disclosure.
FIG. 2 is a view for describing a dissolution behavior of carbon dioxide by a
fine bubble generator in wet ammonia cleaning according to Embodiment 1 of the
present disclosure.
10 FIG. 3 is a schematic view showing the configuration of the wet ammonia
cleaning equipment according to Embodiment 2 of the present disclosure.
FIG. 4 is a schematic view showing the configuration of the wet ammonia
cleaning equipment according to Embodiment 3 of the present disclosure.
FIG. 5 is a schematic view showing the configuration of a fertilizer production
15 plant including the wet ammonia cleaning equipment according to Embodiment 4 of
the present disclosure.
DETAILED DESCRIPTION
[0009] Hereinafter, a wet ammonia cleaning equipment according to embodiments
20 of the present disclosure will be described with reference to the drawings. The
embodiments each indicate one aspect of the present disclosure, do not intend to limit
the present disclosure, and can optionally be modified within a range of a technical
idea of the present disclosure.
[0010] The wet ammonia cleaning equipment of the present disclosure treats a basic
25 gas containing ammonia generated from, for example, a fertilizer production plant.
Specifically, the wet ammonia cleaning equipment removes ammonia from the basic
5
gas by bringing the basic gas containing ammonia into gas-liquid contact with an
absorbent. However, the basic gas covered by the present disclosure is not limited to
a basic gas generated from the fertilizer production plant, but the present disclosure
covers a basic gas containing ammonia regardless of where the basic gas is generated.

We Claim:
1. A wet ammonia cleaning equipment for treating a basic gas containing
ammonia, comprising:
5 an ammonia scrubber for bringing the basic gas into gas-liquid contact
with an absorbent containing carbon dioxide; and
a fine bubble generator for producing the absorbent from carbon dioxide
and water,
wherein the fine bubble generator includes at least:
10 a first fine bubble generator for producing a first absorbent from carbon
dioxide and water; and
a second fine bubble generator for producing the absorbent from carbon
dioxide and the first absorbent.
15 2. The wet ammonia cleaning equipment according to claim 1,
wherein the fine bubble generator generates carbon dioxide bubbles each
of which is not greater than 100 micrometers in size.
3. The wet ammonia cleaning equipment according to claim 2,
20 wherein the first fine bubble generator is an ejector type fine bubble
generator, and the second fine bubble generator is a pressurized dissolution
type fine bubble generator.
4. The wet ammonia cleaning equipment according to any one of claims 1 to 3,
25 wherein the ammonia scrubber includes an absorbent circulation line for
extracting the absorbent stored in the ammonia scrubber to be returned into a
26
gas phase in the ammonia scrubber, and
wherein the fine bubble generator is disposed on the absorbent
circulation line.
5 5. The wet ammonia cleaning equipment according to claim 4,
further comprising a membrane separator for removing ammonia from
the absorbent flowing through the absorbent circulation line,
wherein the membrane separator is disposed on the absorbent circulation
line to be located upstream of the fine bubble generator in a flow direction of
10 the absorbent.
6. The wet ammonia cleaning equipment according to any one of claims 1 to 5,
further comprising a cooling device for cooling the basic gas before the
basic gas flows into the ammonia scrubber.
15
7. A fertilizer production plant for producing a fertilizer from a raw material gas
containing methane, comprising:
an ammonia synthesis unit for producing ammonia from the raw material
gas;
20 a urea synthesis unit for producing a urea solution by reacting the
ammonia with carbon dioxide;
a urea granulation unit for producing granular solid urea from the urea
solution; and
the wet ammonia cleaning equipment according to any one of claims 1
25 to 6 for treating the basic gas generated from the urea granulation unit,
wherein the fertilizer production plant is configured such that carbonated
27
water generated in the fertilizer production plant is supplied into a gas phase
in the ammonia scrubber or to the fine bubble generator.
8. The fertilizer production plant according to claim 7,
5 wherein the urea synthesis unit includes:
a urea production device for producing the urea solution; and
a compressor for supplying carbon dioxide to the urea production device,
and
wherein the carbonated water is drain generated in the compressor.
10
9. The fertilizer production plant according to claim 7 or 8,
further comprising a reformer for reforming the raw material gas with air
and steam before the raw material gas flows into the ammonia synthesis unit,
wherein the carbonated water is condensate contained in a gas flowing
15 out of the reformer.