AxFlow VAPOUR RECOVERY SYSTEMS
AxFlow focus on Blackmer compressor technology for product and vapor recovery. Blackmer are the industry leaders in vapour recovery units VRU as their oil-free, reciprocating compressors are designed for specific applications in LPG and NH3 gas handling, product transfer and vapor recovery.
Designed specifically for liquified gas transfer duties, AxFlow's systems use Blackmer vertical piston compressors which come in single or two stage versions with air or water cooling. The Blackmer single-stage reciprocating compressor creates a low-pressure area in the compression chamber, when the piston moves from the highest point of the stroke to the lowest point. The gaseous product (at a higher pressure in the tank) moves into the compression chamber whereupon this volume of gas is reduced as the piston moves to the top of the stroke with a corresponding increase in pressure.
Single stage compressor units for vapour recovery can attain very high temperatures which mean that not all the gas is recovered. This can overcome by using two- stage units. The two stage units are used for liquid recovery, but can also be used for vapour recovery. The two stage unit gives the user greater flexibility for reclaiming, vapour, gas and liquids. The new gases have higher vapour pressure and these, together with other factors are producing demand for recovery systems. The lower the GWP the higher the degree of flammability. The benefit of the AxFlow double stage VRU is that it can switch between single and double stage operation as and when required.
AxFlow vapour recovery systems are available in stand-alone configurations and as packages engineered to meet customer's specific requirements, whether for continuous gas transfer, liquid transfer or gas evacuation down to pressures of 50 millibar absolute. They are suitable for displacements of up to 212 m3/h and system pressures up to 42 bar.
To meet the varying requirements for tanker emptying, AxFlow offers compressor and pump packages, both for fixed and transportable installations. Transportable VRU's enable them to be used at various locations around a plant. These skid-mounted vapour recovery systems take the gas from the container, compress it before condensing it into a liquid via a water-cooled plate heat exchanger and then pass it into the receiving container for onward storage. At the latter stages of vapour recovery the pressure in the container drops until it reaches atmospheric pressure and at this point the vacuum pump is started. This pre-boosts the compressor and pulls out the remaining vapour in to the receiving container as before. Thus, the combination of compressor and vacuum pump removes almost the entire residual product to give maximum product recovery.
Unlike conventional vapour recovery units. that can leak vapor due to inefficient crankcase sealing and containment, Blackmer’s patented isolation chamber design and piston seals prevent oil contamination and cylinder blow-by.