How is distillation a chemical reaction and its application

Is distillation a chemical reaction is a question that many are interested in. It is important to understand distillation is not a chemical reaction, it is an example of pressure being used as a means to accomplish a chemical reaction. As such, distillation falls within the realm of physicochemical processes that occur at low temperatures and pressures. To make this clear, distillation has many different definitions other than simply being the transfer of substances between two phases in liquids by vaporization and condensation.

Common application of distillation

1. Distillation of crude oil

A distillation unit is used to convert volatile fractions from crude oil into a more valuable mix, such as a glycol mixture. The difference between the oils of different tar grades, their molar percentages and boiling points, can be easily measured at the first Stationary Distillation Unit (SDU) and extracted at the second. This extract is then heated in a steam-heated Boiler Isotherm Distillation Condenser (BIDC) and cooled in a Cooling Jacket Absorber (CJA). At this point, the feed will have a different composition than when it entered the SDU. The distillation process is used to separate the crude oil into fractions that can be used as fuels, or that can be processed further into other products. This helps to answer the question, is distillation a chemical reaction.

2. Distillation of toxic vapor streams of ammonia and nitric acid

Through distillation, refinery operations may include recovery of ammonia and hydrochloric acid from the spent acidic steam. For example, a 100-tonne-per-day (100t/d) ammonia recovery unit in Saudi Arabia was designed to recover 350 tonnes per day (350t/d) of ammonia from 80% strength and 370 tonnes per day (370t/d) from 65% strength feedstock. The design also included a T-296-C/D, 150kW (200hp) reciprocating compressor with a 50% duty cycle; flow is 40 lpm (cbm). The ammonia recovery unit was designed to operate at a maximum outlet temperature of 160C and an exit pressure of 1.2 MPa.

3. Distillation of water from coal gas

The separation process involves the use of distillation to separate out the various components found in coal gas into their respective components. In this process, water is used as the feed material into a number of different stages where it will eventually be separated into its constituent parts and cooled before being drawn off through the appropriate exit valve.

4. Distillation of air into oxygen and nitrogen

In the process of distillation, air is passed through an air-cooled reactor (rectifier) with two to four stages. Each stage is charged with a liquid mixture of alcohol (95%) and water (5%). It is extracted from the rectifier using a cooler with an exit temperature of about 35℃. Typically, one tonne per day of such rectified air produces 350 kg of liquid oxygen and 1000 kg of liquid nitrogen per day. The first stage has two vessels, each charged with 18% hydrogen peroxide solution as the coolant; each vessel has 9000-1000 L capacity and uses 3333 kW input power. The second stage has two vessels with 8% benzene solution as coolant.

5. Methanol and water vapor separation

Methanol is a widely used chemical in the production of plastics, methanol dehydrates to form methane. Methane is a fuel and its production emits less carbon dioxide than the production of gasoline. In an industrial process, when methanol is produced by catalytic oxidation of ethanol, it contains significant quantities (about 50% to 70%) of carbon dioxide and water. While these gases can be used for air conditioning or for powering natural gas-fired power plants, the carbon dioxide does not belong in the final product and consequently must be eliminated from the system.

6. Distillation of water for industrial uses

Water and other substances need to be separated from each other in processing to produce different desired final products. The separation of water from other substances may be accomplished by distillation. The process uses a difference in boiling points between the two materials being separated, usually at very low temperatures. A number of different types of heat exchangers can be used to increase the temperature where the liquids are boiled.

In conclusion, is distillation a chemical reaction? No! As can be seen, the answer is quite simple when all the terms are defined properly. Distillation is pressure put on liquids to separate them into their components. It then occurs at low temperatures and low pressures in order to achieve the separation.