Background 

In the cannabis ethanol extraction process, a vacuum environment is needed in three  steps, Winterization and filtering, rotary evaporation, and distillation. Each step needs a  different vacuum pressure. Oil-lubricated rotary vane pumps and water-ring pumps are  used.

Winterization and Filtering Process 

The filtered crude oil needs to be deep-frozen, which is what they call winterization. In a  low temperature and vacuum state, the wax/tar substance is extracted from the  flocculent crude oil, and finally, the flocculent wax lipid becomes a gel wax.

Figure 1 Winterization and Filtering Process 

The existing vacuum pump for this process is a water-ring vacuum pump, SHZ-95B,  whose ultimate vacuum pressure is about 33mBara.

Rotary Evaporating

Figure 2 Rotary Evaporation Process 

After filtration, ethanol is needed to be separated from the substance. A rotary  evaporator is required to do the job. A vacuum pump keeps the pressure at 70mBara (- 0.094MPag) in the flask to lower the boiling point of ethanol. Currently, the customer  uses the same water-ring pump, SHZ-95B. 

Distillation 

The substance needs a distillation process to isolate enriched component fractions of  extracts. Since terpenes, THC, and CBD have high boiling points (156-250°C; 312-482°F),  distillation under atmospheric conditions is undesirable. Exposure to oxygen at these  high temperatures can promote oxidation and prolonged heat exposure leads to  thermal decomposition. By applying a vacuum, the boiling points are lowered. Vacuum  conditions remove oxygen, thus eliminating product oxidation while lowering the boiling  point temperature to lessen heat exposure.

Figure 3 Diagram of Vacuum Distillation

To match the volume of system, the customer uses a two-stage rotary vane oil pump,  2XZ-6B, whose pumping speed is 360L/min (6L/s). During the process, the pressure of  the system is maintained at 0.45mBara.

Figure 4 Rotary Vane Pump 2XZ-6B in distillation process

However, for oil pumps, oil change and maintenance increase the cost of operation. Oil  molecules might contaminate the extracted substance as well.  For water-ring pumps, the water circulating, cooling and hygiene system, high power  consumption, and maintenance also lead to high operation costs and lower product  quality. To reduce the operation cost, the customer decided to test whether oil-free scroll  vacuum pumps can fit in to replace oil pumps and water-ring pumps.

Performance Comparison between water-ring  pump and SVF-E1-100PC oil-free scroll vacuum  pump 

SVF-E1-100PC oil-free scroll vacuum pump is applied to both winterization/filter process  and rotary evaporation process. The ultimate vacuum of SVF-E1-100PC is 330 times lower than that of the water-ring pump. This low vacuum ensures a continuous stable  suction flow of extracts. It improves extract quality and makes productivity up  20%~30%. In other words, to do the same amount, it saves a lot of time and reduces the  cost by using SVF-E1-100PC.

Specification Comparison

Based on the performance, SVF-E1-100PC consumes about 50% of the power. It is more  efficient than the water-ring pump. Besides, SVF-E1-100PC is much lighter and more  compact. Here are the typical operating costs of both pumps.

Comparison of Operation Costs

* No maintenance is required for 20,000 hours (more than 6 years) 

** The cost is minimum and in most cases the oil change needs to be more frequent.

*** Cost of down time is not included. 

The list price of an oil-free scroll vacuum pump is higher than that of a water-ring pump  system. But, by using SVF-E1-100PC, you can reduce overall operating cost as the  following items.

• Less than half of power consumption. 

• Save 20~30% process time. 

• No cost of maintenance. 

• No down time due to maintenance.

PERFORMANCE COMPARISON SVF-E1-100 AND SVFE1-200PC OIL-FREE SCROLL PUMP VS. 2XZ-6B  ROTARY VANE PUMP 

In the distillation process, rotary vane oil pump can be replaced by SVF-E1-200PC oil-free scroll vacuum pump. 

Specification Comparison

The pumping speed of an SVF-E1-100PC is less than 1/3 of that of a 2XZ-6B. A single SVFE1-100PC pump can’t maintain the vacuum pressure at 0.45mBara but 0.77mBara. This  means the pumping speed is a little bit lower. Replacing with an SVF-E1-200PC, the  problem solves. The vacuum pressure is no higher than 0.45mBara.

Figure 5 Single SVF-E1-100PC in the distillation process

Compared to oil pumps, it is more economical using SVF oil-free scroll vacuum pumps.  The overall operating cost is lower. Here are the minimum costs of both SVF pump and  rotary vane oil pump.

Comparison of Operation Costs

* No maintenance is required for 20,000 hours (more than 6 years) 

** The cost is minimum and in most cases the oil change needs to be more frequent. 

*** Cost of down time is not included.

Conclusion 

Based on the test, SVF series pumps are ideal for the ethanol extraction process.  Compared to rotary vane pumps and water-ring pumps, here are the main advantages  of SVF pumps. 

• More compact and lighter • More efficient (less power consumption and more productivity) 

• Good vacuum pressure is equivalent to or better than that of oil pumps 

• Maintenance-free 

• No ballast valves to handle water vapor and liquid. 

• No contaminants to the extracted product. 

• Much quieter during operation.