Do You Know the Difference Between Active And Passive Closed Loop Systems?

1. Introduction

Closed loop extractor is a professional setting. It consists of a tank containing solvent, a column for hold dry plant, a collection tank, a vacuum pump, a recovery pump and a refrigerant scale for effectively measuring the weight of the solvent recovery tank. It is much safer than an open blast extraction system. In the extraction process, no solvent is exposed to air, which is contained in a closed loop system. Because there is no expose, it can successfully use the solvent in a safe and closed environment, and can reuse the solvent to reduce the risk of explosion.

2. Difference between Passive and Active Closed Loop Extractors

The passive closed loop extractor is realized by controlling temperature and pressure. In a closed loop, gas always seeks the lowest pressure it can reach. By ensuring that the pressure at the receiving end is low, hydrocarbon gas can be transferred from the high-pressure part of the system to the low-pressure part. This is achieved by controlling the temperature. The pressure of hydrocarbon is directly related to the temperature. If the temperature is lower than the boiling point of the solvent, the vapor will be recondensed into a liquid. Butane vapor is automatically moved to a cooler area by heating the collected butane and cooling it to a low pressure tank. This method is a simple method of solvent recovery, usually for beginners to learn how to operate the closed loop extraction system.

A recovery pump is added to the active closed loop extractor than to the passive closed loop extractor. The pump uses push / pull action to help the solvent vapor move. This approach also helps reduce ongoing costs by reducing the need for expensive refrigerants such as dry ice. The solvent is condensed into liquid through a coil located on the pump output port. This method reduces the amount of dry ice and forms a fast and effective recovery. Due to the combination of effective condensation of steam and the force generated by the pump, the solvent recovery is often faster when the pump is used. This method does not need to cool the low-pressure water tank, but with the increase of the closed-loop capacity, the cost of the active extaction system will also increase.

The main differences between passive and active closed loop extractors

(1) The Principle is Different.

The passive system uses differential heat to recover butane, and the active system uses pump to recover butane. For the passive closed loop extractor system, when the butane is to be transferred back to the recovery device of the passive system, the recovery tank shall be placed in dry ice and the collection pipe shall be placed in 90 ° water. Butane condenses from hot to cold. For the passive type, a vacuum must also be formed on the recovery tank before recovery. For active systems, a pump can be used instead of a temperature.

(2) The Speed is Different.

The operation speed of passive  closed loop system is slower than that of active closed loop extractor, and there are not many functions from the perspective of product. The active closed loop extractor system uses recovery pumps to speed up solvent recovery.

(3) The Cost is Different.

The cost of passive closed loop system is lower and the cost of active system.

(4) Solvent Loss is Different.

Passive closed loop extractors tend to lose more solvents, so the solvent loss per operation is usually higher than active loop extractor syste, because the recovery pump can be pumped into the vacuum, the residual solvent in the extract will be less, so the solvent loss per operation will be smaller.

(5) Parts Maintenance is Different.

The main disadvantage of the active closed loop extractor is that the pump needs regular maintenance and modification. Sometimes the seal must be replaced, so more attention is needed.