Thermal Fluid Heating & Air Compression Systems
Thermal Fluid Heating
The heating of fluids is performed in technical furnaces, which often have forced circulation. They are coated inside with refractory material, and the burners are usually at the bottom of the oven. In the convection zone, they usually have an economizer to take advantage of the sensible heat of the smoke, heating a quantity of thermal fluid to be used to preheat air for combustion. There is a pressure control chamber that acts on the vanes, opening or closing the output of the gases into the chimney.
Air Compression and Distribution
Compression Methods
Four methods are used to compress gases; two are intermittent, and two are continuous:
- Consecutive quantities are introduced into a confined gas compound. The volume is reduced, thereby increasing the pressure, and then the compressed gas is ejected out of the enclosure.
- Consecutive quantities of gas are introduced into a confined space. No change in volume occurs until the discharge opening, where it is compressed by the backflow of gas from the discharge system. Then the compressed air is expelled outside the enclosure.
- Gas is compressed by mechanical action due to rapidly rotating impellers or rotors with fins, increasing the speed and pressure of the gas. (Subsequently, speed is converted into pressure in stationary nozzles or vanes).
- Gas is introduced at a high speed into a jet of the same gas or another, and the high speed of the mixture is converted to pressure through a diffuser.
Compressors that use methods 1 and 2 are running intermittently and are known as displacement compressors.
Those that use method 3 are called dynamic compressors.
Those that use method 4 are normally known as ejectors and operate at vacuum pressure, less than atmospheric.
Types of Compressors
Positive Displacement Compressors
These are units in which successive volumes of gas are locked in a closed space and elevated to a higher pressure.
Reciprocating Compressor
These are positive displacement machines in which the compression element is a piston that has a reciprocating motion inside a cylinder.
Rotary Compressors
These are machines in which compression and displacement are carried out by the action of rotating elements.
Fin Compressors
These are positive displacement rotary machines in which axial fins on a rotor slide radially, mounted eccentrically in a cylindrical casing. The gas is trapped between the fins and compressed.
Liquid Ring Compressors
These are displacement rotary compressors that use water or other liquid as a piston to compress and move the handled gas.
Screw Compressors
These machines are rotary displacement compressors in which two rotating, helical-shaped screws compress and move the gas to the discharge. Internal compression does not occur.
Dynamic Compressors
These are continuous flow rotary machines in which a rapidly rotating element accelerates the gas as it passes through the element, converting speed into pressure, partly on the rotating element and partially in stationary diffusers.
Centrifugal Compressors
These are dynamic machines in which one or more rotating impellers accelerate the gas. The main gas flow occurs radially.
Axial Compressors
These are dynamic machines in which the acceleration of the gas is produced by the action of a rotating curved blade. The main gas flow occurs in an axial direction.
Mixed Flow Compressors
These are dynamic machines with an impeller that combines some features of the centrifugal and axial types.
Ejectors
These are elements that use a high-speed stream of gas or vapor to entrain the gas, converting the velocity into pressure in a diffuser.
Distribution Networks
An appropriate design of the internal network of compressed air pipes (Intranet) varies depending on building size, number of points of air consumption, and their location. The core network must have a closed loop. A certain number of closed circuits can be employed for each floor, connecting each link to a main artery. On the ground, in trenches, with branches hanging from the side walls or ceiling.