What conditions are most favorable for operation of the sieve bed?

What conditions are most favorable for operation of the sieve bed?

In general, higher sieve adsorption capacity is favored by lower temperature and higher pressure. This also help to lower the feed water concentration for water saturated applications. There is a balance to be maintained though in order to avoid approaching the hydrocarbon dewpoint in vapor phase systems. It is recommended to maintain operation at 10-20°F (5.5-11°C) above the dewpoint in order to avoid potential two phase flow. Mixed phase is always to be avoided given that adsorption and working capacity are negatively affected and can be unpredictable when this occurs. As a result, operation should always be 100% vapor phase or 100% liquid phase. For regeneration, lower pressure is favored for minimized flow rate and better turbulence, and lower temperature is favored for optimum sieve life. There are practical limitations and the heating temperature typically falls within a given range depending upon the type of sieve being used and the application details. Temperatures that are too low are too inefficient and may not remove enough contaminant; temperatures that are too high will cause accelerated coking and can cause decomposition of stream components. Pressure typically cannot be too low due to excessive velocity in the up flow direction that will cause bead movement; pressures that are too high require additional flow or time, and higher risk of regeneration refluxing and laminar flow.

Recent Articles