CHEMICALS AND ALLIED APPLICATION NOTE 4.01.07 CONTACT PROCESS: SULFURIC ACID AND OLEUM www.kpatents.com
SULFURIC ACID, H2SO4 AND OLEUM
Typical end products Fertilizers, explosives, dyes, and petroleum products Introduction Chemical curve: Sulfuric acid R.I. per Conc b.w. at Ref. Temp. of 20˚C Sulfuric acid (H2SO4) is a dense, colorless liquid
Range 0-80% when at room temperature. It is a very active chemical and is widely used in the preparation of nD large number of chemicals. This strong inorganic 1.4500 acid is also inexpensive to manufacture. 1.4300 Concentrated sulfuric acid (93-98%) is used in the
1.4100 manufacturing of fertilizers, explosives, dyes and petroleum products. Stronger acids can be made by 1.3900 dissolving sulfur trioxide (SO3) in 98 to 99% acid.
1.3700 Sulfuric acid is widely sold in the form of various solutions of H2SO4 in water or of SO3 in H2SO4. The 1.3500 latter mixture is called fuming sulfuric acid or oleum. Its marketing is based on the percentage of SO3 1.3300 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 present. concentration (%)
Range 85-100% Application
Sulfuric acid and oleum are produced industrially in nD contact plants. The contact process forms sulfur 1.4440 trioxide gas from sulfur dioxide (SO2) and oxygen in
1.4400 a catalyst tower. Sulfuric acid is formed when water is added. A mixture of H2SO4 and free SO3 is 1.4360 equivalent to a sulfuric acid concentration of 100
1.4320 percent.
1.4280 Gases containing sulfur trioxide are passed through oleum towers. The towers contain recirculated oleum 1.4240 and sulfuric acid, which irrigate sulfur trioxide.
1.4200 Typically, 30-60% of the sulfur trioxide present in the 88.0 90.0 92.0 94.0 96.0 98.0 100.0 concentration (%)
CHEMICALS AND ALLIED APPLICATION NOTE 4.01.07 CONTACT PROCESS: SULFURIC ACID AND OLEUM www.kpatents.com
gas is absorbed because of oleum vapor-pressure final product is viscous with a temperature of 80ºC limitations. Since absorption of SO3 is incomplete, (176ºF) containing small air bubbles, which is a the gas leaving the oleum absorption tower must be source for errors in density meters. These errors can processed in a subsequent sulfuric acid absorption be eliminated by using a digital K-Patents tower. refractometer to provide precise and reliable concentration measurements. Measurement ranges Depending on the desired product concentration, the in this application are: concentration 22-35% and tower is irrigated with 22% or 35% oleum at a temperature 60-80°C (140-176°F). temperature of 40-50°C (104-122°F). By adding concentrated sulfuric acid from the absorber, the The K-Patents refractometer wetted parts are either desired oleum concentration is achieved. Finally total plastic or metal alloys, depending on corrosion oleum is cooled through a heat exchanger. resistance requirements. Both storage tanks and process piping in a sulfuric acid plant can be Installation stainless steel, providing that the sulfuric acid concentration never drops below 95%. Less The K-Patents Process Refractometer is used in the concentrated acid is very aggressive and requires drying and in the absorber tower to keep the chemically resistant Teflon material (PR-23-M or concentration of H SO constant at 93, 98 or 104% 2 4 PR-23-W) to ensure a viable service life. by weight.
The K-Patents refractometer can also be installed in a control loop measuring the concentration of oleum to ensure the correct final concentration. The
Instrumentation Description Teflon Body Refractometer PR-23-M. A compact refractometer for chemically aggressive solutions and ultra-pure fine chemical processes. Connected to the process by a G1/2" female or a 1/2" NPT process connection. It has a built-in flow cell designed to keep all metal and other easily corroding parts from coming into contact with the process liquid.
Saunders Body Refractometer PR-23-W. A heavy-duty refractometer for chemically aggressive liquids in large-scale production and in large pipe sizes (diameter 50, 80 or 100mm/2", 3" or 4"). The Saunders body material is graphite cast iron, which provides a solid mechanical base. A PFA-lining ensures the chemical resistance.
K-Patents Process Refractometer PR-23-GP is an industrial refractometer for large pipe sizes and tanks, cookers, crystallizers and kettles. Installation through a flange or clamp connection.
Measurement range: Low: 0-80% H2SO4 High: 85-100% H2SO4 0-30% Oleum