The method of purification of tail gases from nitrogen oxides
(57) Abstract:Use: for cleaning the tail gases from nitrogen oxides in nitric acid production. The inventive method tail gas treatment unit includes heating to a temperature of 260-350oC with subsequent supply to the reactor selective treatment and heated to the temperature of the tail gas before it enters the gas turbine, characterized in that the heating of the tail gas to temperatures 260-350oC are in a separate combustion chamber of the reactor. 1 Il. The invention relates to methods of selective treatment of tail gases from nitrogen oxides in nitric acid production.Known methods of purification of tail gases from nitrogen oxides at different temperatures are heated prior to being fed into the reactor selective treatment and a different arrangement of the reactors. During operation of the catalyst, its activity changes and to restore the necessary changes in the temperature of the tail gas to the inlet of the reactor selective treatment.In existing methods, it is possible to do, however, change other process parameters that affect the process as a whole and make interdependent ml of the TCA is the way, described in the flowsheet unit AK-72 M (Olevsky Century M nitric acid Production in units of large capacity. M. Chemistry, 1985, S. 295, Fig. 5-35. The prototype). Tail (exhaust) gases are heated in the block BG-172 (Fig. 5-36 ibid) gas after the turbine and then fed into the reactor selective treatment. After cleaning warm up to temperatures of the order of 780oC and fed into the gas turbine. However, to raise the temperature of the tail gas before selective clearing is necessary to change the gas temperature after turbine, and this, in turn, requires an increase of the gas temperature before the turbine, which is not always possible.The task of the invention the extended temperature range of operation of selective treatment without change in the other temperature parameters in the technology of production of nitric acid.Technically, the problem is solved by heating the tail gas before selective clearing in a separate external combustion chamber of a reactor, then heated in a separate combustion chamber of the turbine and fed into the gas turbine.The drawing shows a diagram of an installation for implementing the method. Tail gases enter the combustion chamber of the reactor is key 2 and already peeled warm in the heater 3 to the gas temperature before the turbine. Studies of the dependence of activity of the selective catalyst from the term and temperature reflected in the examples below.Example 1 (prototype). It is known that the highest activity of the catalyst is achieved when the temperature at the inlet of the reactor selective treatment 300oC. At this temperature before the turbine 780oC.The tail gases is mixed with ammonia and heated to a temperature of maximum activity of the catalyst 300oC and sent to the reactor selective treatment, then heated to 780oC. the aging of the catalyst selective treatment, the highest activity of the catalyst was achieved at 350oC. To ensure this it is necessary to raise the temperature before the turbine above 780othat is impossible due to the destruction of the turbine at these temperatures. In the result, continue to operate at 300oC, but with deteriorating cleanup.Example 2. The greatest activity of the catalyst is achieved when the temperature at the inlet of the reactor selective treatment 300oC. the maximum possible temperature before turbine 780oC.The tail gases is mixed with ammonia and heated to a temperature of 300oC in a separate 780oC in the heater. With the aging of the catalyst for selective treatment, the highest activity of the catalyst was achieved at 350oC. To ensure the tail gases, mixed with ammonia, heated to a temperature of 350oC in a separate external combustion chamber of the reactor selective treatment. After cleaning, hold their heat to 780oC. Purification is not affected.Example 3. In the reactor selective treatment downloading more effective catalyst, the highest activity of which is achieved at 260oC. At this temperature before the turbine to ensure its high efficiency, is supported within 780oC.The tail gases is mixed with ammonia and heated to a temperature of 260oC in a separate external combustion chamber of a reactor, and then fed into the reactor in the reactor selective treatment. After cleaning gas is directed to a heater, where it is heated to 780oC. Purification is not affected.If necessary to raise the temperature to a higher temperature, proceed in accordance with example 2.The given examples show that the proposed method of tail gas treatment unit of nitrogen oxides from nitric acid production (example 2 and 3)UP>oC (example 2); a decrease from 300 to 260oC (example 3) without compromising the efficiency of the turbine, i.e., without changing the temperature before the turbine (780oC) and all other parameters of the technological scheme remain unchanged due to the heating of the tail gas in a separate (standalone) external combustion chamber of the reactor. Way tail gas treatment unit, comprising heating to 260 - 350oWith subsequent supply to the reactor selective treatment and heated to the temperature of the tail gas before it enters the gas turbine, characterized in that the heating of the tail gas to 260 350oWith lead in a separate combustion chamber of the reactor.
FIELD: physical or chemical processes and apparatus.
SUBSTANCE: method comprises flowing air through the chemical absorber of nitrogen acids that is composed of chemically absorbing base that absorbs nitrogen dioxide and sorbent-oxidizer that oxidizes nitrogen mono-acid up to nitrogen dioxide. The chemical absorber is made of n pairs of layers of chemically absorbing base and sorbent-oxidizer. Upon flowing throughout n pairs of the layers, the initial concentration of the nitrogen dioxide drops by a factor of 3n, where n is the total number of pairs of the layers.
EFFECT: reduced cost and enhanced efficiency.
2 cl, 1 tbl
FIELD: methods of purification of flue gases.
SUBSTANCE: the invention is pertaining to the method of purification of flue gases and may be used to decrease the outbursts of nitrogen oxide with the help of the method of the high-temperature selective non-catalytic reduction. The method provides for feeding of the previously prepared steam-gaseous reduction mixture into the gas flue of the flue gas burning aggregate with the temperature of the flow of the purification gases of 700-1200°C. At that the steam-gaseous reduction admixture is prepared in the connected to the gas flue high-speed reactor during 0.5-5 seconds by introduction of a water solution of carbamide with a superheated steam at the pressure of 3-10 atm. Concentration of the water solution of carbamide makes 20-40 mass %. The time of the contact of the water solution of carbamide with the superheated steam predominantly makes 0,5-2 seconds. The pressure in the reactor predominantly makes 3-6 atm. The temperature of the superheated steam makes 200-400°C. The invention ensures simplification of the production process of purification of the effluent gases from nitrogen oxides, to increase the level of purification of such a gas in the broad range of the temperatures of the purified combustion products, and also to decrease significantly the share of the secondary contaminant - ammonia, in the purified gases.
EFFECT: the invention ensures simplification of the production process of the effluent gases purification from nitrogen oxides, to increase the level of purification of the gases in the broad range of the temperatures of the purified combustion products, to decrease significantly the share of the secondary contaminant - ammonia in the purified gases.
5 cl, 2 ex, 1 dwg, 2 tbl
FIELD: chemical industry; methods of neutralization and a utilization of the aggressive chemical compounds.
SUBSTANCE: the invention is pertaining to the field of neutralization and a utilization of the aggressive chemical compounds, in particular, the saturated with the anhydrides acid-containing compounds and wastes. The neutralization is applied to the smoke mixture containing the sulfuric anhydride and chlorosulfonic acid, or the oxidizing agent of the rocket propellant based on of the nitric acid containing a dimer of the nitrogen dioxide. For neutralization use the hydrolyzed dispersible aluminosilicates based of the natural clays selected from: hydromicaceous Cambrian clay, montmorillonite clay, kaolinite clay or on the basis of their mixtures. At that the hydrolyzed dispersible aluminosilicates, which are taken at least in equal shares with an aggressive chemical compound, are prepared at the following ratio of components (in mass shares): a dry substance - 1.0-2.5, water - 1.0. The invention allows to neutralize the aggressive wastes and to produce the useful product with the sorption activity.
EFFECT: the invention ensures neutralization of the aggressive wastes and production of the useful product with the sorption activity.
3 cl, 2 ex, 6 tbl
FIELD: gas purification.
SUBSTANCE: method comprises treating the flow of chimney gas in the high-temperature zone with a temperature of 700-1200°C by means of gas reducing mixture that is preliminary is produced by thermal decomposition of solid carbamide out of the zone for treating the gas and is supplied to the zone of purification by the gas-carrier. The carbamide is decomposed by rising its temperature from 100 to 600°C. The rate of the temperature rise is 5-40°C/min and 35-40°C/min for the temperature range from 100 to 400°C and temperature higher than 400°C, respectively.
EFFECT: simplified method.
3 cl, 1 dwg, 1 tbl
FIELD: non-catalytic method of reduction of nitrogen oxide emission in combustion product flow.
SUBSTANCE: proposed method includes bringing in contact effective amount of at least one nitrile compound fed to combustion apparatus in form of separate liquid flow or in form of separate gas flow with flow of wastes fed to combustion apparatus in non-separated form, additional fuel flow and air at temperature sufficient for reduction of NOx emission in flow of combustion products.
EFFECT: reduction of nitrogen oxide emission in combustion product flow.
13 cl, 4 tbl, 3 ex
FIELD: cleaning waste flue gases of tubular furnaces used in power technological plants of ammonia production process from nitrogen oxides.
SUBSTANCE: proposed method includes mixing flue gases with air and ammonia-containing reductant. Used as ammonia-containing reductant are synthetic gases of ammonia production process of the following composition, mass-%: ammonia, 20-30; methane, 18-24; hydrogen, 25-35; argon, 3.8-4.8; the remainder being nitrogen. Selective catalytic reduction of nitrogen oxides of flue gases is performed in reactor at temperature of 240-450°C with the use of tungsten-vanadium catalyst. Proposed method makes it possible to clean flue gases to 91%.
EFFECT: high degree of cleaning.
FIELD: cleaning exhaust gases from nitrogen oxides in industrial plants by means of selective catalytic cleaning with the use of ammonia.
SUBSTANCE: proposed method includes reduction of nitrogen oxides by ammonia on catalyst in presence of hydrogen. Before delivery to catalyst, exhaust gases are mixed with purge gases from the ammonia synthesis cycle. Content of hydrogen in mixture is maintained below low limit of ignition. Purge gases are enriched with ammonia by mixing them with ammonia synthesis gases.
EFFECT: reduced consumption of ammonia; enhanced mixing of exhaust gases with ammonia; reduced emissions of ammonia into atmosphere; reduced power requirements.
FIELD: inorganic synthesis catalysts.
SUBSTANCE: decomposition if N2O under Ostwald process conditions at 750-1000°C and pressure 0.9-15 bar is conducted on catalyst, which comprises (A) support composed of α-Al2O3, ZrO2, SeO2, or mixture thereof and (B) supported coating composed of rhodium or rhodium oxide, or mixed Pd-Rh catalyst. Apparatus wherein N2O is decomposed under Ostwald process conditions on the above-defined catalyst is also described. Catalyst is disposed successively downstream of catalyst grids in direction of stream of NH3 to be oxidized.
EFFECT: increased catalyst activity.
8 cl, 2 tbl, 3 ex
FIELD: chemical industry; other industries; methods of the selective non-catalytic purification of the flue gases from nitrogen oxides.
SUBSTANCE: the invention is pertaining to the processes of the selective non-catalytic purification of the flue gases from nitrogen oxides and may be used for reduction of the contents of the nitrogen oxides in the low-temperature flue gases from the fuel-burning installations. The method of the selective non-catalytic purification of the flue gases from nitrogen oxides provides for feeding in the flow of the end flue gases having the temperature 200-700°С of the gaseous reduction mixture previously produced by the joint thermal decomposing of carbamide and hydrogen peroxide at the temperature of 150-500°С. For production of the gaseous reduction mixture they use either the water solutions of carbamide peroxihydrate or carbamide and hydrogen pyroxide, either carbamide peroxihydrate in the solid kind. The reduction gas mixture is fed by means of the carrier gas, in the capacity of which use the water steam, the flue gases, the compressed air, nitrogen. The concentration of the water solutions of carbamide and hydrogen peroxide makes 1-40 mass % and 0.5-20 mass %. The technical result of the invention is the increase of efficiency of purification of the flue gases from nitrogen at the low temperatures without formation of the secondary contaminants.
EFFECT: the invention ensures the increased efficiency of purification of the flue gases from nitrogen at the low temperatures without formation of the secondary contaminants.
4 cl, 3 tbl, 2 ex
SUBSTANCE: principle refers to catalyst and method of complex purification of waste gases of different production, heat and power utilities, automobile transport, which works on natural gas (methane). Described is a method of complex purification of effluent gases from nitrogen oxides, carbon oxide and hydrocarbons and it involves passing the effluent gases at temperatures 455-600°C through a layer of mechanical mixture of nickel chromium oxide industrial catalyst a copper zink nickel industrial catalyst in a volume composition of 1:1 to 20:1 respectively. To the effluent gases, methane up to a volume composition of CH4/O2 0.07-0.15 can be added before passing it through the catalyst layer. Nickel chromium oxide industrial catalyst contains NiO 38-42 %; ZnO 28-32 %; NiO 4-6 % and not less than Al2O3 17 % masses.
EFFECT: increasing of the purifying index of effluent gases.
3 cl, 4 ex