What type of reboiler is suitable for the solvent regeneration tower? Siphon or kettle-type?

1 Introduction A reboiler (also known as a boiling reboiler) is, as the name implies, a device that vaporizes a liquid once again. Its structure is similar to that of a condenser, but one is used for cooling, while a reboiler is used to heat and vaporize. 2. Uses: Reboilers are often used in conjunction with distillation columns; a reboiler is a special type of heat exchanger that enables heat exchange while also providing a space for vaporization. The liquid level of the material in the reboiler is at the same height as the liquid level in the distillation tower. The liquid phase is supplied from the bottom of the tower into the reboiler. Typically, 25-30% of the liquid phase is vaporized in the reboiler. The vaporized two-phase flow is sent back to the distillation column; the gaseous components returning to the column rise through the trays, while the liquid components fall to the bottom of the column. The material expands or even vaporizes when heated in the reboiler, resulting in a decrease in density; as a result, it leaves the vaporization zone and returns smoothly to the tower. The gas-liquid mixture that returns to the tower has the gas phase rising through the trays while the liquid phase falls to the bottom of the tower. Due to the effect of the static pressure difference, the liquid level at the bottom of the tower is continuously replenished to replace the amount that has evaporated. 3 Features 1. The overall heat transfer coefficient is more than 2 times that of carbon steel and stainless steel shell-and-tube heat exchangers ； 2. High temperature and pressure resistance ； 3. Thanks to its fully arc-shaped flexible structure, it enables variable cross-sectional flow of the fluid, creating positive and negative pressure differences; as a result, it has a very strong ability to remove and prevent scale formation ； 4. The wall thickness is thin (0.8–1.0 mm); the corrugated structure of the wall generates no stress, there is no temperature gradient, and the fluid temperature becomes uniform almost instantly ； 5. Low voltage drop ； 6. The stress distribution is uniform, with no tearing or cracking occurring ； 7. The heat exchange tube bundle can be removed, extracted, repaired, and cleaned ； 8. Under the same conditions, a heat exchange area of 60% that of carbon steel and stainless steel is sufficient to meet the operational requirements. 4 Types: Upright: thermosyphon type, forced circulation type; Horizontal: thermosyphon type, forced circulation type, kettle reboiler, built-in reboiler. Upright thermosyphon: ▲Circulation driving force: the density difference between the liquid in the kettle and the gas-liquid mixture in the heat exchanger tubes. ▲Compact structure, small footprint, and high heat transfer coefficient. ▲The shell side cannot be mechanically cleaned, and it is not suitable for heat transfer media with high viscosity or that are dirty. ▲The tower bottom provides a space for gas-liquid separation and a buffer zone. Horizontal thermal siphon: ▲Circulation driving force: the density difference between the liquid in the tank and the gas-liquid mixture in the heat exchanger’s heat transfer tubes. ▲It has a large footprint, a moderate heat transfer coefficient, and is easy to maintain and clean. ▲The tower bottom provides a space for gas-liquid separation and a buffer zone. Forced circulation type: ▲Suitable for materials with high viscosity and heat sensitivity, solid suspensions, as well as systems with a long heat absorption phase and high resistance due to low evaporation ratios. Kettle reboiler: ▲High reliability, easy to maintain and clean. ▲It has a low heat transfer coefficient, a large shell volume, occupies a lot of space, has high costs, and is prone to scaling. Built-in reboiler: ▲ Simple structure. The heat transfer area is small, resulting in unsatisfactory heat transfer performance. Problem 5: Scaling: Reboilers are widely used in chemical plants. A reboiler (also known as a boiling reactor) enables liquids to vaporize once again; it is a special type of heat exchanger that allows for heat exchange while simultaneously vaporizing liquids ； Often used in conjunction with distillation columns ； The material expands or even vaporizes when heated in the reboiler, its density decreases, allowing it to leave the vaporization zone and return smoothly to the tower. After long-term use, material scale accumulates in the heat exchange tubes. As this scale layer grows thicker, production efficiency decreases, and it may even lead to shutdowns. The reboiler can be cleaned using cleaning agents to remove the scale. Corrosion: During the production process, the tube sheets of heat exchangers are subject to erosion by moisture, cavitation, and corrosion from trace amounts of chemical substances. This often leads to leaks at the welds of the tube sheets, resulting in a mixture of water and chemical materials. It also makes it difficult to control the temperature during the production process, leading to the formation of other products and severely affecting product quality as well as reducing its grade. After leaks occur in the welds of the condenser tube sheet, companies typically use conventional welding methods to carry out repairs. Internal stresses are likely to arise within the tube sheet, and these stresses are difficult to eliminate, leading to leaks in other heat exchangers as well. Companies test the condition of the repaired equipment by applying pressure, and they repeat the welding process and testing procedures; it takes 2–4 people several days to complete the repairs. After a few months, corrosion reoccurs in the welds of the tube sheet, resulting in wasted manpower, resources, and financial costs, as well as increased production expenses. Thanks to the corrosion resistance and erosion resistance of Fushilan polymer composite materials, by providing protection for the new heat exchangers in advance, it is possible to effectively address issues such as weld defects and sand holes in these heat exchangers. Moreover, it prevents chemical substances from corroding the metal surface and welding points of the heat exchangers over time. During future regular maintenance, Fushilan polymer composite materials can also be applied to protect the exposed metal surfaces ； Even if leakage occurs after use, it can be repaired promptly using the Fushilan technology, preventing prolonged surfacing repairs from disrupting production. It is precisely this level of meticulous management that **reduces the likelihood of leakage problems in heat exchangers**. It not only lowers the cost of purchasing such equipment but also ensures product quality and production efficiency, thereby enhancing the competitiveness of the products.

For various reasons, we use thermal siphon systems; many other factories also employ kettle-type systems.

The question is: for the regeneration of desulfurization solvents, which form is better?

Have you encountered any problems with using your siphon type?

Early designs mostly used thermosiphonic types, but due to reasons such as corrosion, axial structures are now generally used. Thermosyphonic reboilers mainly suffer from corrosion in the gas-liquid return line.

The moderator is right; I think the same way. The kettle-type gas-liquid separator provides good separation effects, and it’s less likely to suffer from corrosion when returning fluid to the tower

The choice of form depends mainly on the material

The 8th floor is the correct answer; the key is to consider the material – if scaling does not occur easily, thermal siphonning works very well. Reactor-type systems for the same type of material are more prone to scaling. Additionally, due to the poor fluidity in reactor types, some materials undergo carbonization and coking; therefore, a forced circulation system is necessary to address this issue.

The kettle type is great – excellent design and easy to operate!

The original poster is talking about the reboiler for solvent regeneration; the material itself is already specified, so there isn’t a lack of scope for discussion.