Method and device for ammonia storage and delivery using in situ re-saturation of a delivery unit
Disclosed is a method for storing and delivering ammonia, wherein a first ammonia adsorbing/absorbing material having a higher vapor pressure at a given temperature than a second ammonia adsorbing/absorbing material is used as an ammonia source for said second ammonia adsorbing/absorbing material when said second adsorbing/absorbing material is depleted of ammonia by consumption, and a device for performing the method.
1 . A device for providing ammonia to a consumption unit ( 8 , 9 ) comprising
at least two different ammonia storage materials capable of ab- or adsorbing and desorbing ammonia;
a first storage container ( 4 ; 4 a , 4 b ) with a first ammonia storage material having a first ammonia vapour pressure in saturated form at a given temperature;
a second storage container ( 1 ; 1 a , 1 b ) with a second ammonia storage material having a second ammonia vapour pressure in saturated form at said given temperature;
said second ammonia vapour pressure being lower than said first ammonia vapour pressure;
heating means ( 3 ) for heating the second storage material to release ammonia from the second storage container ( 1 ; 1 a , 1 b );
first means ( 5 , 10 , 13 ) for delivering gaseous ammonia from the second storage container ( 1 ; 1 a , 1 b ) to the consumption unit ( 8 , 9 ); and
second means ( 12 ; 12 a , 12 b , 12 c , 12 d ; 12 e , 12 f ) for delivering ammonia from the first storage container ( 4 ; 4 a , 4 b ) to the second storage container ( 1 ; 1 a , 1 b ).
2 . A device according to claim 1 , wherein the vapour pressure of the first ammonia storage material and the second ammonia storage material measured at the same reference temperature, differs by more than a factor of 2.
3 . A device according to claim 1 , wherein the ammonia vapour pressure of the first ammonia storage material and the second ammonia storage material measured at the same reference temperature differs by equal or less than a factor of 2.
4 . A device according to claim 1 , wherein the ammonia vapour pressure of the first storage material is below one bar measured at room temperature (298k).
5 . A device according to claim 4 , wherein the ammonia vapour pressure of the second storage material is below 0.1 bar measured at room temperature (298k).
6 . A device according to claim 1 , wherein at least one of the at least two storage materials is a metal ammine complex.
7 . A device according to claim 6 , wherein the metal lammine complex is of the general formula: M a (NH 3 ) n X z , wherein M is one or more cations selected from alkali metals, alkaline earth metals, and/or transition metals, X is one or more anions selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate, and phosphate ions, a is the number of cations per salt molecule, z is the number of anions per salt molecule, and n is the coordination number of 2 to 12.
8 . A device according to claim 7 , wherein the second ammonia storage material is Mg(NH 3 ) 6 Cl 2 .
9 . A device according to claim 7 , wherein the first ammonia storage material is Sr(NH 3 ) 8 Cl 2 or Ca(NH 3 ) 8 Cl 2 or a combination thereof.
10 . A device according to clam 8 , wherein the second ammonia storage material is Mg(NH 3 ) 6 Cl 2 and the first ammonia storage material is Sr(NH 3 ) 8 Cl 2 or Ca(NH 3 ) 8 Cl 2 or a combination thereof.
11 . A device according to claim 1 , wherein any absorption of ammonia into the first storage container ( 4 ; 4 a , 4 b ) is prevented wither by a suitable one-way valve or a closed valve ( 12 ) during release of ammonia from the second ammonia storage container ( 1 ; 1 a , 1 b ).
12 . A device according to claim 1 , wherein the first storage container ( 4 ; 4 a , 4 b ) is also equipped with heating means.
13 . A device according to claim 1 , wherein the first storage container ( 4 ; 4 a , 4 b ) is insulated.
14 . A device according to claim 1 , wherein the first and/or the second ammonia storage material is compacted to a unit with a density of a above 75% of the theoretical maximum skeleton density of the saturated solid ammonia storage material.
15 . A device according to claim 1 , in which desorbed ammonia is delivered to a catalyst ( 8 ) for a selective catalytic reduction of NOx in an oxygen-containing exhaust gas from a combustion process or engine ( 7 ).
16 . A device according to claim 1 , wherein the desorbed ammonia is delivered to a fuel cell, either
(a) directly, or
(b) via a catalytic ammonia cracking reactor for cracking ammonia into hydrogen and nitrogen.
17 . A device according to claim 1 for providing ammonia to a NOx removing system ( 8 ) with control means ( 11 ) for controlling said first ( 5 , 10 , 13 ) and/or second ( 12 ; 12 a , 12 b , 12 c , 12 d , 12 e , 12 f ) delivery means.
18 . A device according to claim 1 , comprising means ( 5 , 10 , 11 , 13 ) for controlling and introducing gaseous ammonia from the first storage container ( 4 ; 4 a , 4 b ) into an exhaust line ( 9 ) before a NOx reduction catalyst ( 8 ) and
means ( 12 ; 12 a , 12 b , 12 c , 12 d , 12 e , 12 f ) for connecting the first ammonia storage container ( 4 ; 4 a , 4 b ) and the second ammonia storage container ( 1 ; 1 a , 1 b ).
19 . A device according to claim 18 , wherein the means ( 12 ; 12 a , 12 b , 12 c , 12 d , 12 e , 12 f ) for connecting the first ammonia storage container ( 4 ; 4 a , 4 b ) and the second ammonia storage container ( 1 ; 1 a , 1 b ) comprise a valve ( 12 ).
20 . A method for storing and delivering ammonia, wherein a first ammonia storage material capable of ad- or absorbing and desorbing ammonia having a higher vapour pressure at a given temperature than a second ammonia storage material capable of ad- or absorbing and desorbing ammonia is used as an ammonia source for said second ammonia storage material when said ammonia storage material is depleted of ammonia by consumption.
21 . A method according to claim 20 wherein the first and said second ammonia storage materials are contained in different containers in fluid communication.
22 . A method according to claim 20 , wherein said fluid communication can be interrupted and reassumed.
23 . A method according to claim 20 , wherein the vapour pressure of the first ammonia storage material and the second ammonia storage material measured at the same reference temperature, differs by more than a factor of 2.
24 . A method according to claim 20 , wherein the ammonia vapour pressure of the first ammonia storage material and the second ammonia storage material measured at the same reference temperature differs by equal or less than a factor of 2.
25 . A method according to claim 20 , wherein the ammonia vapour pressure of the first ammonia storage material is below one bar measured at room temperature (298k).
26 . A method according to claim 25 , wherein the ammonia vapour pressure of the second ammonia storage material is below 0.1 bar measured at room temperature (298k).
27 . A method according to claim 20 , wherein at least one of the first and second ammonia storage materials is a metal ammine complex.
28 . A method according to claim 27 , wherein the metal ammine complex is of the general formula: M a (NH 3 ) n X z1 wherein M is one or more cations selected from alkali metals, alkaline earth metals, and/or transition metals, X is one or more anions selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate, and phosphate ions, a is the number of cations per salt molecule, z is the number of anions per salt molecule, and n is the coordination number of 2 to 12.
29 . A method according to claim 28 , wherein the second ammonia storage material is Mg(NH 3 ) 6 Cl 2 .
30 . A method according to claim 28 , wherein the first ammonia storage material is Sr(NH 3 ) 8 Cl 2 or Ca(NH 3 ) 8 Cl 2 or a combination thereof.
31 . A method according to claim 29 , wherein the second ammonia storage material is Mg(NH 3 ) 6 Cl 2 and the first storage material is Sr(NH 3 ) 8 Cl 2 or Ca(NH 3 ) 8 Cl 2 or a combination thereof.
32 . A method according to claim 20 , wherein the first and/or the second ammonia storage material is compacted to a unit with a density of a above 75% of the theoretical maximum skeleton density of the saturated solid ammonia storage material.
33 . A method according to claim 20 , in which desorbed ammonia is delivered to a catalyst for a selective catalytic reduction of NOx in an oxygen-containing exhaust gas from a combustion process or engine.
34 . A method according to claim 20 , wherein the desorbed ammonia is delivered to a fuel cell ( 15 ), either
(a) directly, or
(b) via a catalytic ammonia cracking reactor ( 14 ) for cracking ammonia into hydrogen and nitrogen.
35 . A method according to claim 22 , wherein the fluid communication is interrupted while the second ammonia storage material is heated for desorption of ammonia, and the fluid communication is reassumed when the heating is stopped.