High performance Synloop heat exchangers to superheat steam, generate high pressure or medium pressure steam and to pre-heat BFW.
Reliable and robust design.
Casale has developed a reliable, robust and high performance heat exchanger for the heat recovery section of the synthesis loop.
The main products designed by Casale are:
- Synloop steam super-heater
- HP and MP synloop WHB
- HP and MP BFW pre-heater
The synloop steam superheater is typically a horizontal exchanger (TEMA type DFU) located (when present) immediately downstream of the ammonia converter. This heat exchanger can be directly connected nozzle to nozzle with the converter or by means of an external pipe. The direct connection layout is the preferred option: i.e. the exchanger inlet nozzle is directly connected to the bottom of the converter.
The synloop WHB is a NKU special type horizontally arranged with process gas flowing tube side. The hot gas from upstream equipment enters the head that is equipped with an internal gas inlet/outlet channel. The hot gas coming from converter enters the internal part of the channel, then enters the ""U"" pipes where is cooled by producing steam and flows outside this internal chamber, cooling down the pressure retaining wall of the channel.
This gas path is permitted by the fountain type distribution of the U tubes that are made of two different bundles having the inlet on the center of the tube sheet and the outlet on its periphery. The fountain type design reduces the thermal stresses and provides longer life to this critical equipment.
Insulated ferrules protect inlet tubes keeping the hot end tube wall temperature inside the tube sheet below 380°C to avoid nitriding.
Also the BFW pre-heater design is supplied to efficiently recover the energy available in the synthesis loop and to provide energy saving to the ammonia plant.
If one of the above heat exchangers is located downstream the ammonia converter then Casale can provide the a direct connection between ammonia converter and downstream exchanger.
This feature of Casale layout, avoids the installation of pipe subjected to high temperature operating conditions: in fact, the conditions of syngas leaving the converter are favorable for a nitriding attack.
Therefore, the high pressure high temperature pipe should be made of stainless steel material. this features is providing economical saving to the synloop installation and a safer operation.