EP0287224A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Methods of removing NOx and SOx emissions from combustion systems using nitrogenous compounds
Assignee: Energy and Environmental Research Corp
•
Filing: 1988-03-23
•
Granted: —
•
Expires: 2008-03-23
Abstract
Abstract The present invention relates to methods for selectively reducing NO x so that nitrogen can be removed from emission effluent streams and NO x emissions can be reduced to very low levels. In addition, the present invention teaches a method whereby NO x and SO x may be simultaneously removed from the effluent stream. The present invention teaches the reduction of NO x with -NH and -CN containing selective reducing agents such as ammonium sulfate, urea, NH₃, and cyanuric acid. Initially, the selective reducing agent is decomposed in a fuel-rich environment to form highly reactive decomposition products. The reaction of the selective reducing agent to produce its decomposition products, such as NH, NH₂, isocyanic acid, and related reaction intermediates, takes place in an oxygen-free, fuel-rich decomposition zone with the reaction temperature in the range of from about 300°F (150°C) to about 3000°F (1650°C). After the selective reducing agent is decomposed in the absence of oxygen, the decomposition products are contacted with the effluent stream containing NO x . At this point the oxygen level of the stream must be carefully controlled to provide an excess of oxygen so that the selective reduction of the NO x species will occur. It may be necessary at this point to inject air into the effluent stream in order to maintain the proper oxygen-rich (fuel-lean) conditions for NO x reduction. In this second "reaction zone," NO x reduction takes place at temperatures of from approximately 500°F (260°C) to approximately 2600°F (1425°C). The present invention can also be used in conjunction with SO x control technology. Specifically, species used to control SO x , such as limestone, dolomite, quicklime, and hydrated lime, can be added in conjunction with the selective reducing agent for simultaneous NO x and SO x control.
Inventors
- 👤 Michael P. Heap
- 👤 James M. Mccarthy
- 👤 Shih L. Chen
- 👤 David W. Pershing
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 05:56
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/60; B01D53/54; B01D53/56; F; F02; F02B; F02B2275/00; F02B2275/14; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
152 words
A process for selectively reducing nitrogen oxides in combustion effluent streams characterized in that it comprises the steps of: a) introducing a reducing agent into a gaseous decomposition zone, said reducing agent having at least one functional group selected from the group comprising -NH and -CN, wherein the decomposition zone is substantially oxygen deficient and is maintained at a temperature in the range of from approximately 300°F (150°C) to approximately 3000°F (1650°C); b) allowing the reducing agent sufficient residence time within the decomposition zone to allow for substantial mixing of the reducing agent and gaseous species within the decomposition zone; c) introducing the resulting mixture from the decomposition zone to a reaction zone containing combustion effluents, said reaction zone having an excess of oxygen; and d) allowing the mixture from the decomposition zone sufficient residence time within the reaction zone to allow the reduction of the NO x within the combustion effluents.
Claim 2
Dependent Claim
152 words
A process for selectively reducing nitrogen oxides in combustion effluent streams characterized in that it comprises the steps of: a) introducing a reducing agent into a gaseous decomposition zone, said reducing agent having at least one functional group selected from the group comprising -NH and -CN, wherein the decomposition zone is substantially oxygen deficient and is maintained at a temperature in the range of from approximately 300°F (150°C) to approximately 3000°F (1650°C); b) allowing the reducing agent sufficient residence time within the decomposition zone to allow for substantial mixing of the reducing agent and gaseous species within the decomposition zone; c) introducing the resulting mixture from the decomposition zone to a reaction zone containing combustion effluents, said reaction zone having an excess of oxygen; and d) allowing the mixture from the decomposition zone sufficient residence time within the reaction zone to allow the reduction of the NO x within the combustion effluents.
Claim 3
Dependent Claim
25 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claim 1 characterized in that the selective reducing agent is cyanuric acid.
Claim 4
Dependent Claim
60 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claims 1 or 2 characterized in that the temperature within the decomposition zone is within the range of from approximately 1400°F (760°C) and approximately 1800°F (980°C) and the temperature in the reaction zone is maintained in the range of from approximately 1200°F (650°C) to approximately 1800°F (980°C).
Claim 5
Dependent Claim
24 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claim 1 characterized in that the selective reducing agent is urea.
Claim 6
Dependent Claim
51 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claim 1 characterized in that the selective reducing agent is a compound selected from the group consisting of ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium formate, ammonium oxalate, ammonia, biuret, triuret, NH₂CN, Ca(CN)₂, CaCN₂, NaOCN, dicyanodiamide, and melamine.
Claim 7
Dependent Claim
64 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1, 4, or 5 characterized in that the temperature within the decomposition zone is within the range of from approximately 1200°F (650°C) to approximately 1900°F (1040°C) and the temperature in the reaction zone is maintained in the range of from approximately 800°F (425°C) to approximately 2400°F (1300°C).
Claim 8
Dependent Claim
118 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 6 characterized in that it also comprises: a) introducing an SO x removal agent into the stream of combustion effluents, said combustion effluents having a temperature in the range of from approximately 800°F (425°C) to approximately 2800°F (1540°C) at the point at which the SO x removal agent is introduced; and b) allowing the resulting mixture sufficient residence time to allow the reaction of SO x with the SO x removal agent whereby SO x is also removed from the combustion effluent stream, said residence time being in the range of from approximately 50 milliseconds to approximately 5 seconds.
Claim 9
Dependent Claim
35 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claim 7 characterized in that the SO x removal agent is selected from the group consisting of limestone, quicklime, and hydrated lime.
Claim 10
Dependent Claim
55 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 8 characterized in that the residence time within the decomposition zone is about 5 milliseconds to about 5 seconds and the residence time within the reaction zone is from approximately 30 milliseconds to approximately 5.0 seconds.
Claim 11
Dependent Claim
52 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 9 characterized in that the equivalent mole ratio of nitrogen in the reducing agent to NO x in the combustion effluent stream is in the range of from approximately 0.5:1 to approximately 10:1.
Claim 12
Dependent Claim
47 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 10 characterized in that the equivalent mole ratio of nitrogen in the reducing agent to NO x is in the range of from approximately 0.7:1 to approximately 3:1.
Claim 13
Dependent Claim
43 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 11 characterized in that the air to fuel stoichiometric ratio in the decomposition zone is within the range of approximately 0.7 to approximately 1.0.
Claim 14
Dependent Claim
33 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 12 characterized in that the fuel-rich decomposition zone is produced by using fuel injection.
Claim 15
Dependent Claim
47 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 13 characterized in that the excess of oxygen within the reaction zone is achieved by the injection of a gas or air containing oxygen into the decomposition zone.
Claim 16
Dependent Claim
45 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 14 characterized in that the reducing agent is introduced into the decomposition zone as a dry solid, as an aqueous solution, or as an alkanolic solution.
Claim 17
Dependent Claim
56 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 15 characterized in that the effectiveness of the reaction zone is enhanced by the addition of a radical generating promoter selected from the group consisting of hydrogen, methanol, natural gas, propane, carbon monoxide, and light petroleum fuels.
Claim 18
Dependent Claim
54 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 16 characterized in that the effectiveness of the reaction zone is enhanced by the use of a catalyst selected from the group consisting of stainless steel, Pt, Pd, W, Ni, Co, Au, Ag, and Mn.
Claim 19
Dependent Claim
34 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 17 characterized in that the SO x removal agent is added as a dry powder.
Claim 20
Dependent Claim
32 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to any one of claims 1 to 18 characterized in that the SO x removal agent comprises a CaO slurry.
Claim 21
Dependent Claim
29 words
A process for selectively reducing nitrogen oxides in combustion effluent streams according to claim 19 characterized in that a surfactant is added to the slurry to enhance emission reduction.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.