Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2002-08-13
2004-08-31
Davis, Brian (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S498000, C564S437000, C564S439000, C423S228000, C423S229000, C096S363000, C096S364000
Reexamination Certificate
active
06784320
ABSTRACT:
TECHNICAL FIELD
This invention relates to an amine recovery method and apparatus, and a decarbonation apparatus having the amine recovery apparatus.
BACKGROUND ART
In recent years, thermal power equipment and boiler equipment have used large amounts of coal, heavy oil or superheavy oil as fuels. From the points of view of air pollution control and Earth environment purification, there have been problems in how to decrease the quantities and concentrations of emissions of sulfur oxides (mainly sulfur dioxide), nitrogen oxides, and carbon dioxide. Suppression of carbon dioxide emission, in particular, has recently been investigated, together with emission control of flon gas and methane gas, from the viewpoint of global warming. For this purpose, methods for removing carbon dioxide, such as PSA (pressure swing) method, membrane separation, and absorption by reaction with basic compounds, are under study.
As an example of a method for removing carbon dioxide with the use of basic compounds, Japanese Unexamined Patent Publication No. 1993-184866 (related U.S. Pat. No. 5,318,758) proposes a method which performs decarbonation by using an aqueous solution of an amine compound (hereinafter referred to simply as an amine) as a solution for absorbing carbon dioxide. In this method, the reaction between carbon dioxide and the amine compound is an exothermic reaction. Thus, the temperature of the absorbing solution in a carbon dioxide absorption section rises to raise the vapor pressure of the amine. That is, the amine-containing absorbing solution evaporates owing to the temperature increase. As a result, the amount of the amine compound accompanying a decarbonated gas increases. Thus, a water washing section is provided in an absorption tower, and the decarbonated gas and washing water are subjected to vapor-liquid contact in the water washing section, whereby the amine compound accompanying the decarbonated gas is recovered into a liquid phase.
Concretely, the above-mentioned Japanese Unexamined Patent Publication No. 1993-184866 discloses a decarbonation apparatus as shown in
FIGS. 2 and 3
.
In
FIG. 2
, the reference numeral
1
denotes an absorption tower,
2
a carbon dioxide absorption section,
3
a water washing section,
4
an exhaust gas supply section,
6
is an absorbing solution supply port,
7
a nozzle,
8
a liquid reservoir in the water washing section,
9
a circulating pump,
10
a cooler,
11
a nozzle,
12
an absorbing solution discharge port,
13
a blower,
14
an exhaust gas supply port,
15
an exhaust gas cooler,
16
a circulating pump,
17
a cooler,
18
a nozzle, and
19
a drainage line.
Although a detailed explanation is omitted, a combustion exhaust gas supplied through the exhaust gas supply port
14
is cooled by the cooling tower
15
, and then fed to the absorption tower
1
. In the carbon dioxide absorption section
2
of the absorption tower
1
, the fed combustion exhaust gas is brought into countercurrent contact with an absorbing solution supplied through the absorbing solution supply port via the nozzle
7
. As a result, carbon dioxide in the combustion exhaust gas is absorbed and removed by the absorbing solution. The loaded absorbing solution, which has absorbed carbon dioxide, is sent to a regeneration tower (not shown) through the absorbing solution discharge port
12
. In the regeneration tower, the loaded absorbing solution is regenerated, and fed again from the absorbing solution supply port
6
to the absorption tower
1
.
On the other hand, the combustion exhaust gas decarbonated in the carbon dioxide absorption section (i.e., decarbonated exhaust gas) ascends, accompanied by a large amount of an amine vapor, due to a temperature rise ascribed to an exothermic reaction between carbon dioxide and an amine compound in the carbon dioxide absorption section
2
. The ascending decarbonated exhaust gas passes through the liquid reservoir
8
, and heads toward the water washing section
3
. In the water washing section
3
, reserved water in the liquid reservoir
8
is transported by the circulating pump
9
, cooled by the cooler
10
, and then supplied to the water washing section
3
as washing water through the nozzle
11
. As a result, this washing water and the decarbonated exhaust gas make countercurrent contact in the water washing section
3
, whereby the amine compound in the decarbonated exhaust gas is recovered into the liquid phase.
FIG. 3
is characterized by improving the amine recovering ability by utilization of regeneration tower refluxed water. In
FIG. 3
, the reference numeral
21
denotes an absorption tower,
22
a carbon dioxide absorption section,
23
a water washing section,
24
an exhaust gas supply port,
25
an exhaust gas discharge port,
26
an absorbing solution supply port,
27
a nozzle,
28
a regeneration tower ref luxed withdrawn water supply port,
29
a nozzle,
30
a cooler,
31
a nozzle,
32
a charging section,
33
a circulating pump,
34
a make-up water supply line,
35
an absorbing solution discharge pump,
36
a heat exchanger,
37
a cooler,
38
a regeneration tower,
39
a nozzle,
40
a lower charging section,
41
a reboiler,
42
an upper charging section,
43
a refluxed water pump,
44
a carbon dioxide separator,
45
a carbon dioxide discharge line,
46
a cooler,
47
a nozzle,
48
a refluxed water supply line, and
49
a combustion gas supply blower.
Although a detailed explanation is omitted, a combustion exhaust gas supplied by the combustion gas supply blower
49
is cooled by the cooling tower
30
, and then fed to the absorption tower
21
. In the carbon dioxide absorption section
22
of the absorption tower
21
, the fed combustion exhaust gas is brought into countercurrent contact with an absorbing solution supplied through the absorbing solution supply port
26
via the nozzle
27
. As a result, carbon dioxide in the combustion exhaust gas is absorbed and removed by the absorbing solution. The loaded absorbing solution, which has absorbed carbon dioxide, is sent to the regeneration tower
38
by the absorbing solution discharge pump
35
through the absorbing solution discharge port
12
. In the regeneration tower
38
, the loaded absorbing solution is regenerated, and fed again to the absorption tower
21
through the absorbing solution supply port
26
.
On the other hand, the combustion exhaust gas decarbonated in the carbon dioxide absorption section
22
(i.e., decarbonated exhaust gas) ascends, accompanied by a large amount of an amine vapor, owing to a temperature rise ascribed to an exothermic reaction between carbon dioxide and an amine compound in the carbon dioxide absorption section
22
. The ascending decarbonated exhaust gas heads toward the water washing section
23
. In the water washing section
23
, part of regeneration tower refluxed water withdrawn as washing water is supplied to the water washing section
23
through the regeneration tower ref luxed withdrawn water supply port
28
via the nozzle
29
. As a result, this washing water and the decarbonated exhaust gas make countercurrent contact in the water washing section
23
, whereby the amine compound in the decarbonated exhaust gas is recovered into the liquid phase.
However, according to the above-described conventional decarbonation apparatus shown in
FIG. 2
, in particular, the water washing section is provided as one stage. Thus, the concentration of amine recovered by the washing water is so high that the recovery of amine is insufficient. As a result, amine accompanies the decarbonated exhaust gas, and is released to the outside of the decarbonation process system. Consequently, amine is wasted, causing a concern about an increase in the operating cost, etc.
The present invention has been accomplished in the light of the foregoing problems. Its object is to provide an amine recovery method and apparatus, and a decarbonation apparatus equipped with the amine recovery apparatus, the amine recovery method and apparatus being capable of efficiently recovering an amine compound accompanying a
Hirata Takuya
Ishida Kazuo
Mimura Tomio
Nakashoji Hiroshi
Nojo Takashi
Davis Brian
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
The Kansai Electric Power Co. Inc.
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