• Categories:News Center
• Time of issue:2022-05-06 11:27

(Summary description)Everyone has heard of the terms dilute phase transport and dense phase transport, but not much is known about what these terms actually mean, how these flow patterns affect pneumatic conveying systems, and what risks are posed. First, let's clear up some misconceptions about dense phase pneumatic conveying: Myth 1: High pressure systems are all dense phase pneumatic conveying systems Incorrectly, the air pressure in the system has little direct effect on the flow pattern. To convey material at a certain concentration, a certain pressure gradient (pressure per unit length) is required. Obviously, if we need to deliver long distances, the total pressure required will be higher than for shorter distances to maintain a certain pressure gradient. Therefore, the use of high-pressure conveying may be purely due to the distance required to convey, rather than maintaining a high concentration of powder in the pipeline.   Myth 2: Using a delivery tank (pressure vessel) means the system must use dense phase pneumatic conveying Of course, this assumption is related to misunderstanding 1. If we were to use a high pressure system, we would most likely use a send tank as a feeder to provide pressure. However, sending tanks as feeds for dilute-phase pneumatic conveying, as well as for dense-phase conveying, are feasible. In some cases, sending tanks are used only for dilute phase transport over longer distances. Likewise, the delivery tank can also be used for dilute phase pneumatic conveying of abrasives, since there are few moving parts in the delivery tank, and wear is greatly reduced.   Myth 3: Dense Phase Pneumatic Conveying Systems Never Block This understanding is not correct in a sense. Dense-phase pneumatic conveying has two very different dense-phase flow modes, depending on the physical properties of the powder being conveyed. The fine particle fluidized powder may become blocked when the air pressure is reduced. However, for coarse-grained materials with large gaps, when the airflow rate is reduced, the material will stop flowing and cause embolism. Due to the large gaps between the large particles, there can be air flow in the middle. At the same time, after the embolization, the pressure in front of the embolization position will increase, and the static pressure pushing the embolism will also increase, increasing to a certain extent, causing the embolism to collapse, unblock, and resume delivery. Therefore, the dense-phase pneumatic conveying of large particle materials generally does not cause blockage.