In a petrochemical plant they are using some equipments like boiler, economizer, deaerator and exchagers? Could you please tell me what are these items and how they work? What are the functions of these equipments in the petrochemical company?
The boiler is the steam generator. It usually has a steam drum and many pipes bundled together in a firebox as a heat exchanger. Heat from combustion boils the steam and this steam becomes superheated (well beyond 100 deg. C) in the boiler tubing. In the petrochemical industry the steam temperature may be much lower than power station steam temperatures (depending on the processes the steam is used for). Steam can be better than direct heat from combustion since the degree of temperature control can be very precise (it can be done by metering pressure to determine the exact temperature the steam condenses...keeping constant temperature in a process). The deaerator is a step to remove dissolved gases in the water. Dissolved gases are undesirable since the process works best with pure distilled water in the system (air bubbles in the system may cause problems in many processes). The economizer is an additional heat exchanger that is included in the exhaust stack to pick up the last bit of heat available to warm the incoming water (it is often left out in compact designs such as steam engines on ships). In the petrochemical industry this is often used directly for heat in heat exchangers (dry... in that the steam does not come into contact with the materials it is heating) or wet processes where steam is used directly mixed with a reactant. The steam may be used in fractional distillation (to separate compounds which boil at different temperations) or to cause chemical reactions (which occur at elevated temperatures).
Petroleum taken from the ground is a mixture of various hydrocarbons (chemicals based on hydrogen and carbon). The petroleum is seperated into a variety of items in a refinery to make many of the useful products we need. These may range from fuels such as gasoline, heating oil, waxes, and lubricants. In order to make the seperation, the petroleum is heated in a boiler and the components are seperated in tall columns based on different boiling points. Lighter products, such as kerosene and gasoline boil at a lower temperature than heavier products such as waxes and tars. The boiled vapors are condensed in heat exchangers. The exchangers are basically a series of pipes containing cold water. The cold pipes come in contact with the boiled vapors and the products are cooled and collected.
