Nitric industry today - one of the leading industries.The use of ammonia spread to refrigeration (R717, a refrigerant), medicine (ammonia or ammonia, alcohol), agriculture (fertilizers).
Primary attention is paid to the production of nitrogen fertilizers (which means - and their fundamentals, including ammonia, the demand for which has increased over the past two decades, 20%).
But ammonia production is different, first of all, high energy.The whole history of this production - the struggle for the reduction of energy used (mechanical, thermal, electrical).
Ammonia synthesis reveals the formula:
N2 + 3H2 = 2NH3 + Q
exothermic reaction, reversible, with a decrease in volume.Since the reaction is exothermic, the drop in temperature will shift the equilibrium to the formation of ammonia, however, the reaction rate is significantly reduced.Ammonia production has to go at high temperatures (the synthesis takes place at 500 degrees Celsius).Increased t ° lead to a backlash.Pressure from 15 to 100 MPa allows counteract the effects of temperature (low pressure - from 10 to 15 MPa, the mean pressure - from 25 to 30 MPa, high pressure - above 50 MPa).Of these preferred secondary.
catalyst is a sponge iron containing additives calcium, silicon, potassium, aluminum oxides.
harmful impurities (carbon monoxide, water, hydrogen sulfide) adversely affect the flow velocity of the reaction by poisoning the catalyst thereby reducing its activity and reduce the life.This means that the hydrogen sulfide mixture must pass a thorough cleaning.However, even after purification in ammonia converted only part of the mixture.Therefore, the remaining proportion of unreacted again sent to the reactor.
How is the production of ammonia?
In piped already prepared mixture of three parts hydrogen and one of nitrogen.It passes through the turbocharger, which is compressed to the above-mentioned pressure and sent to the synthesis column with catalyst embedded shelves.The process, as we discovered, highly exothermic.Generate heat heated nitric mixture.From tower leaves about 25 percent of the ammonia and unreacted nitrogen and hydrogen.The whole composition is supplied in the fridge, where the mixture is cooled.Ammonia becomes liquid under pressure.Now the work enters the separator, whose task - separate collection of ammonia at the bottom and the unreacted mixture, which is returned to the circulating pump back to the column.Due to this circulation of nitric mixture is used on 95 percent.Liquid ammonia on the ammonia goes to a special warehouse.
All machines used in production, as airtight as possible, which eliminates leakage.It uses only the energy occurring inside exothermic reactions.The scheme closed, low-waste.The costs are reduced thanks to the continuous and automated process.
Ammonia production has an impact on the environment.Inevitably gas emissions comprising ammonia, carbon oxides and nitrogen and other impurities.Provided low-grade heat.Cleared water after washing and cooling systems of the reactor itself.
Therefore, in the production of ammonia is necessary to include the presence of catalytic purification of reducing gas.Reducing the amount of waste water can be achieved by replacing piston compressors to turbochargers.Low-grade heat can be utilized by entering high-potential heat.However, it will increase pollution of flue gases.
power technology circuit including combined cycle, which uses the heat of steam and combustion products at the same time and increase efficiency, and reduce emissions.
