Chapter 19 book one introduction to therm, oil, heaters, and systems

Question 1

General info

Answer 1

Oil systems is one that uses a thermal fluid in place of steam or water to conduct heat from a central source to other vessels and heating coils in a plant. It is much like a hot water heating system. The main difference is that the fluid used has a much higher boiling point Than water. sometimes referred to as Direct heaters fired heaters or even Direct fired heaters. They can also be unfired steam generators that create steam using electric coils or by recycling heat from exhaust off of fuel fired generators unfired steam generators may be used to produce clean steam which can be used for humidification

Question 2

Principles of thermal heating

Answer 2

Fluid chosen, has much higher boiling point than water they do not present the same operational hazard as high-pressure steam, and do not require licensed operators but furnace fires and hot oil systems can be particularly dangerous and destructive oil. Temperature is sensed at the furnace outlet and controls the amount of fuel flowing into the burner Under normal operation the furnace runs at 235°C to 290°C temperatures over 350°C. The oil can break down and form Coke which will stick to the tubes and generally caused overheating in the system which can be detrimental

Question 3

Three general classes of fired Thermoil heater

Answer 3

Radiant heaters, the combustion gas does not flow across the tube surfaces efficiencies in this type are usually 40 to 50%
Convection heaters combustion gases are made to floor across the outside of the tubes which generally have fins on the outer surface to aid and heat transfer. These heaters have a 75 to 85% efficiency.
Combination radiant and convection

Question 4

Fired Heater Design

Answer 4

Typically a updraft model model that consist of both radiant and convection tube sections convection sections are located in the breaching hot oil enters the heating tubes in the convection section and flows downwards into the radiant section which is located along each wall of the furnace and hot oil exits from the lowest tube on each wall The inner walls and floors are lined with refractory brick or other suitable insulating material. A concrete surrounds the foundation to prevent hot oil from spread and beyond the immediate confines of the heater in the event of a tube rupture

Question 5

Protective devices

Answer 5

Hot oil does not present an explosion hazard like steam does, but it’s ability to burn rapidly is of equal concern hot oil systems are provided with a number of automatic shutdown devices which are called interlocks when I interlock is triggered, the fuel, gas, automatic fuel valve would close to cut off the fuel supply to the main pilot burner

Question 6

Hot oil pump

Answer 6

Usually two pumps with one on standby and are usually a conventional single stage centrifugal pump leave the suction on the standby pump open to keep the pump warm in case it needs to be started. A safety relief valve should be provided in the discharge line in a strainer should be installed in the suction line to the pump, the discharge from the safety relief valve should return the oil back to the oil surge tank in the pump should be located at a level sufficiently below the surge tank to avoid possible cavitation in the pump