1 700 TPD Nitric Acid Plant 700 TPD Nitric Acid Plant Please click on our logo or any link in this presentation to be redirected to our website, or other documentation.Thank You!17A Marlen Drive w Hamilton, NJ w USA Tel: (609) w Fax: (609)
2 General Overview Capacity: 700 ton per day Technology: Uhde Product: Nitric Acid (53% HNO3)
3 General Overview Process Overview Raw Materials and End Products Nitric acid is produced through distilling (burning) ammonia with oxygen from the air and absorption in water. Aside from producing nitric acid, a large quantity of heat is produced which, as much as possible, is converted into steam. This steam is used as a source of energy elsewhere on site. The SZF 4 is a so-called medium-pressure installation with a capacity of 775 ton a day 100% HNO³.Raw Materials and End ProductsAmmonia is delivered by General Supplies. Refuse condensate from the Calcium Ammonia Nitric Acid Factory is used as process-water for production acid.Ignition gas for the distiller (burner), consisting of a mixture of three (3) parts hydrogen gas and one (1) part nitrogen, is supplied by General Supplies.Demineralized water is delivered from the existing demi-installation and is used for the boiler feeding-water, supplemented by the clean cool-water system.The brackish water for the condensor is supplied from the Havenwater pump- station.Oil is used as grease- and regulation-oil for the compressorset.The acid produced (approximately 54% HNO³) is removed to either the production acid-tanks and/or the sales acid-tanks.
4 General Overview Material Data Ammonia Oil (compressors) Ignition Gas Boiling point at 1 bar is -33°C.Minimal ignition-temp. detonationdetonation blend (16-25% vol. %) is 650°C (in air).MAC-value 20 ppmOil (compressors)Congealing point -2°CIgnition point ± 240°CIgnition GasMixture N2 and H2 (1:3)Detonation Limits 5.5 – 72%Nitrogen MonoxideBoiling point at 1 bar is -152°C.MAC-value 25 ppmNitric AcidConcentration 54%MAC-value 2 ppmBoilingpoint at 1 bar 118°CNitrogen DioxideBoiling point at 1 bar is 21°C.MAC-value 2 ppmMAC TGG-15 min. 4 ppm
5 General Overview Preparation of Air and Compression The air, necessary for the distillation (burning) of ammonia is drawn from the atmosphere through an air compressor.Before the air gets into the compressor, the air passes through an air-filter.The drawn-in air is compressed to 3.8 bar. Thereafter, the entire air-stream is divided in two parts. The larger part, approximately 80%, called the primary-air is used for the distillation (burning) of ammonia. The remaining 20% of the air volume is called secondary-air. The secondary-air is cooled in a cooler and used for the degassing of the acid produced.Ammonia/Air BendingLiquid ammonia is evaporated in an evaporator using 20 bar steam. The gasiform ammonia moves to the mixer through a preheater and drop-separator and is blended into the right composition with the primary-air stream. The ammonia/air blend with an ammonia concentration of 10 – 10.5%, is then delivered to the distillers (burners) in the distillation (burning) drums.
6 General Overview Preparation of Air and Compression The ammonia/air blend is delivered to the distillation (burning) drums and flows by way of a separation-sheet to the networks.The distillation (burning) of ammonia takes place on platina-/rhodiumnets at a temperature of approximately 880 °C, following the reaction:4NH³ + 5O² → 4NO + 6H²O + heatand then is partly deoxided through:2NO + O² → 2NO² + heatThe heat is used to generate 20 bar steam and the reheating of the endgas.After distilling (burning) the ammonia/air blend on the nets, the resulting nitrous gases are cooled through sequentially the Pt-recycle cooler, the excess-heater, the evaporator-spirals and the economizer.The temperature of the nitrous gases when exiting the economizer is approximately 320 °C. Further cooling of the nitrous gases takes place in the endgas pre-heaters, in the drum feeding water pre-heater and the gas cooler. The larger part of the water- vapor in the nitrous gases will condensate through the cooling of the gas in the gas- cooler. This results in the production of weak nitric acid of approximately 33%.The weak acid from the gas coolers flows to absorption-tower C-402.
7 General Overview Absorption Two reactions find place in the absorption towers C-401 through C-404:2NO + O² → 2NO² + heat3NO² + H²O→ 2HNO ³ + NO + heatBoth reactions find place in all towers. In the towers there are packs with ceramic Rashig-rings over which the acid circulates. The reaction heat is removed by way of sheet-coolers.Process-water is delivered to tower C-404, and at C %-like nitric acid is removed. The acid is pumped by way of the production-acid tank to the acid degassing. Nitrous gas from the gas-cooler enters the absorption at C-401 and leaves it at C-404.
8 General Overview Acid Degassing The production-acid pump presses the acid using a sprinkler at the top of the acid degassing tower, which is filled with stainless steel Rashig-rings. The production-acid is degassed in the degassing tower in counter-flow with secondairy air. This air originating from the secondairy air-cooler, is delivered at the bottom of the tower. The blend of air and nitrous gas is delivered to absorptiontower C-401. The production-acid is delivered from the bottom of the tower to the production-acid storage tanks and the sales-acid tanks.Leaked acid and acid drained from the entire gas-cooling, oxidation and absorption is gathered and delivered to the leaked-acid tank which is provided with a leaked-acid pump. The pump moves the acid through the suction-pipes to the acid-ciculation and returns it to the absorption.
9 General Overview Reduction Installation The endgas which leaves the absorption towers is heated in endgas preheaters in order to meet the necessary temperature (approximately 270 °C) for the endgas reactor.After it passes through the last preheater and immediately before the NH³-endgas mixer, ammonia is injected in the endgas. The quantity of ammonia injected is determined based on the level of NO³ in the endgas. After the DENOX installation, NO³-content is checked with the use of ammonia. The necessary concentration is monitored using an NO³-meter. Conversion of the nitrous gases takes place in the DENOX-installation with the use of a selective katalysator (vanadium pentoxide).NO + NO² + 2NH³ → 3H²O + 2N² + heat.
10 General Overview The Expansion Turbine Steam Supply Gas from the DENOX installation then flows to the expansion turbine. The endgas expands in the expansion turbine to near atmospheric pressure whilst expelling energy which is used to propel the air compressor. The endgas is blown off through the chimney at a height of 110 m.Steam SupplyThe reaction heat which is released on the Pt/Rh-nets in the distillation(burning) cauldron is used to produce excess-heated steam of 20 bar and 330 °C.The steam system consists of a feedingwater degasser cauldron, a steamdrum, and on top of each distilling (burning) cauldron an economiser, a vaporizer-spiral, a platina-recoup cooler and an excess-heater.In the degasser condensate is delivered from the steam-users, such as the steam turbine 01T, the NH³ preheater and the endgas preheater.
11 General Overview Steam Supply continued Shortage is supplemented with demineralized water. In the degasser water is heated through means of an LD-steam injection to a temperature of 105 °C. The water from the cauldron feeding-water degasser is pumped through the economizer to the steam cauldron to the cauldron feeding water pump.Before the cauldron feeding water enters the economizer, it is first heated from 105 °C to 120 °C through heat exchange in the steam drum.From the steam drum the water is pumped through evaporators by means of a cauldron water circulation pump.The saturated steam, which is developed in these evaporators, leaves the steam drum at the top and is then heated to approximately 330 °C in the excess heater.Part of the approximately 60% of the produced excess heated steam is then delivered to the steam-turbine to propel the air-compressor.The remainder of the excess heated steam is delivered to the so-called 20 bar net.
12 General Overview Process Mono, medium pressure plant (4.5 bar) with 3 burners and an absorption system of 4 packed columns.Equipped with a steam driven Parson compressor train with a Curtis-wheel and a DeNOx installation to reduce NOx emissions to 200 ppmSteam system 20 bar and is integrated with site steam production grid.