Methanol synthesis process and water cooler

Our water coolers use tubes for the water flow, but I personally think it’s better to use shells for that purpose; each approach has its advantages and disadvantages. The following are the excerpts I have taken; please discuss them. The flow direction of the fluids is determined based on the following principles: 1) Fluids that are dirty or prone to scaling should flow inside the tubes, as it is easier to clean them there; 2) Corrosive fluids should also flow inside the tubes, to prevent both the tube bundle and the shell from being corroded, and to facilitate cleaning and maintenance; 3) Fluids with high pressure should flow inside the tubes, to avoid stress being applied to the shell as well; 4) Toxic fluids should flow inside the tubes, to reduce the risk of leaks; 5) Fluids that need to be cooled should flow outside the tubes, as this facilitates heat dissipation and improves the cooling effect; 6) Saturated steam should flow outside the tubes, to make it easier to remove condensate and non-condensable gases, and to keep the steam clean and free from contamination; 7) Fluids with low flow rates or high viscosity should flow outside the tubes, as baffle plates can help achieve turbulence at low Reynolds numbers (Re>100), although multiple tube passes can also be used inside the tubes; 8) If there is a large temperature difference between the two fluids, the fluid with a higher α value should flow outside the tubes, thereby reducing the temperature difference between the tube walls and the shell walls

Small devices are often synthesized using Luchy, while large devices use DAVY. In a synthetic water cooler, the water flows through the shell side

The cooling water should flow through the shell side, as methanol contains small amounts of impurities such as paraffin after cooling; these impurities can be easily removed if the water flows through the tube side

There are also synthetic tower types such as the Ruchi type, Asahi type, Linda isothermal type, and Kedora type

The cooled fluid should flow through the shell side, which facilitates heat dissipation and enhances the cooling effect; in our case, water flows through the tube side.

In the methanol water cooler, the circulating water flows through the shell side, while the methanol synthesis gas flows through the tube side； The choice is mainly based on process considerations and equipment manufacturing; since methanol synthesis in the production process generates paraffin, it is easier to clean if the syngas flows through the shell side ； From the perspective of equipment manufacturing, in a low-pressure methanol synthesis system, the pressure of the syngas is around 5.0 MPa, while the pressure of the circulating water is around 0.4 MPa. It is economical and reasonable to use the tube side for the process gases; simply select high-pressure materials for the heat exchange tubes and end caps, and low-pressure materials for the shell side.

Our cooling water flows through the shell side, which makes cleaning easier; however, not all methanol coolers need to use this design – it depends on your specific circumstances

We have two methanol water coolers; the cooling medium flows through the shell side. The first stage of cooling is carried out using desalinated water, while the second stage uses circulating water. The syngas flows through the tube side, which makes cleaning easier in case of wax formation and also reduces scaling.

It is more economical and reasonable, according to the equipment manufacturer, for water to flow through the shell side and gas to flow through the tube side.

In our water cooler, the water flows through the tube side.

Most of the information provided by Haiyou above refers to recirculating water being used in the shell side; what are your experiences with this approach?

It’s probably because the processes are different for each case. Each family has its own secret recipe

Methanol water cooler: The circulating cooling water flows through the shell side. Syngas flows through the tube side. According to the process requirements, high-pressure fluids should flow in the tube side to avoid shell pressure. If the shell and the tube bundle are compressed together, it increases the amount of metal material used for the shell.

Agree with lgywt. If the syngas flows in the shell side, it increases the requirements for water cooling, and the cost will be much higher than when it flows in the tube side. It also increases resistance at the same time.

Our system uses David’s technology; the water flows through the shell side, which is a more economical approach. In terms of equipment, there are no special requirements from a process perspective.

We use Cassari’s technology here, with water flowing through the shell side; however, the heat exchange efficiency isn’t very good. I’ve heard from some experienced engineers that it’s better to have water flow through the tube side, but I just can’t figure out why!

Water flows through the shell side; in terms of the equipment itself, there are no high requirements regarding the material used, making it economical and practical. Syngas flows in the tube side, as the methanol synthesis reaction involves side reactions that produce wax, and it is easier to remove wax from the tube side.