What is an appropriate value for controlling the coking cycle ratio?

The control of the coking cycle ratio requires comprehensive consideration; below is a piece of information provided by fellow student cswenhan for reference. The recycle ratio is an important operational parameter in coking units; by adjusting it, it is possible to change the product distribution and control the quality of the products. Currently, the recycle ratio of units can be classified into the following four categories: 1. High recycle ratio of 25% – this is primarily aimed at ensuring proper material compatibility by providing wax oil as a raw material for downstream units; the purpose of a high recycle ratio is to control the quality of the wax oil (residue, impurities, final boiling point). 2. Low circulation ratio: 10% 3. Ultra-low circulation ratio: 5% 4. Zero circulation ratio. Comparison of yields for low circulation ratio, ultra-low circulation ratio, and zero circulation ratio: Low circulation ratio, Ultra-low circulation ratio, Zero circulation ratio – Dry gas LV%: 5.59, 5.24, 5.22; Liquefied gas LV%: 8.79, 8.34, 8.32; Liquid product LV%: 72.20, 73.79, 74.50; Coke Wt%: 30.04, 28.69, 27.50. The comparison shows that reducing the circulation ratio can increase the yield of liquid products in coking units. However, reducing the circulation ratio also presents problems: 1. The quality of coker wax oil deteriorates, with increased levels of residue and metals, which affects subsequent processing units. 2. It will promote the formation of projectile char. 3. It is likely to cause coking on the bottom trays of the distillation column. In summary, the circulation ratio should be determined based on the operation of the equipment and the overall material balance of the plant, with the goal of achieving optimal overall efficiency. Adjusting the cycle ratio also allows for adjusting the product distribution; production schemes that prioritize diesel or steam cracking feedstock can be adopted based on market demands and process objectives.

Depending on factors such as the properties of the residue, the load on the heater, and whether pellet coke is formed in the coke tower, which affect normal production, a lower recycle ratio is preferable in terms of processing capacity.

:lol thanks to the two friends above

Most importantly, the processing volume determines your cycle ratio; secondly, it is the product quality and yield you require

This post was last edited by maysee on 2012-4-19 at 14:13. Generally, if the product quality and equipment operation permit it, an operation with the lowest possible cycle ratio is used. The circulation ratio decreases, the coking rate generally drops, while the yield of coker wax oil increases; the yields of gas, gasoline, and diesel decrease. To increase the liquid yield of the unit, it is generally done by reducing the recycle ratio (0.15–0.25) or operating with a zero recycle ratio ； When it is necessary to produce large amounts of coker naphtha and diesel, a larger circulation ratio (0.25–0.45) is generally used in operation ； Operating at a large circulation ratio (0.60–1.0) can increase the aromatic content in the feed to the coke tower, reduce the asphaltenic content, and decrease the residue. When there is no market for the produced gasoline, diesel, and coker wax oil, or when the asphaltenes content in the feedstock is too high, full-cycle or high-cycle ratio operation should be employed. During the large-cycle operation, the wax oil yield decreased significantly, while both the wax oil product and the feed to the heater improved.

Refineries generally require operation at a low circulation ratio, as low-circulation operation can increase the liquid yield. It is generally kept around 1 (1–1.5), while our factory maintains it at 1.3.

The level of the recycle ratio is determined primarily by the following factors: raw material properties, light oil yield, and methods for controlling the liquid level at the bottom of the tower