Rotary Vane Pump for Bitumen Emulsion Batch Transfer

Bitumen Overview and uses

Bitumen (also known as asphalt) is used widely within the construction of pavements, road and roofs. Its room temperature state is solid and is heated up to 170°C for easy application. It can have various states dependent on its temperature from solid, to tar like where it is thick and tacky, and liquid where it flows and can be easily poured.

It has a wide range of uses due to its ability to act as a glue, binding aggregate particles together as in road construction, but also having excellent sealing properties to prevent water ingress, making it ideal for flat roof & road construction and for the coating of pipes to prevent corrosion which may occur when buried. Its durability and low cost of manufacture make it an economical solution for a wide range of uses.

An emulsion is a mixture of fine particles of Bitumen with water, but as this is Petroleum based and the two do not mix, an emulsifier is used to keep particles in suspension, reducing its viscosity greatly and enabling the mix to be easily transferred.

Process Overview

A quarry was looking to transfer Bitumen emulsion from an IBC to a mixer requiring a flow rate of around 150L/min at a height of 4M. They were transferring 100L batches into a mixer via a control system, and needed the fluid to be transferred smoothly into their process.

Being an emulsion the viscosity was around 65cst, which was being used in conjunction with a new process. The bitumen was to be sprayed on to an aggregate mix and the client needed a particular pressure to ensure this was applied evenly.

The customer needed a solution which would ensure the fluid would not harden within the pump, that the unit did not experience wear quickly, was easily serviceable and if an outlet valve was closed that the unit was not damaged. This was an urgent requirement with the customer needing a solution as quickly as possible.

Our Non Clog & Low Maintenance Selection

For this application it is usual for us to select a positive displacement design of pump, from our Gear or Vane Pump range. To minimize wear we needed to select a slow operating pump, as units which rotate too fast struggle with rapid component wear from abrasion but also with more viscous fluids it can struggle to prime.

As the customer was batching fluid with the outlet valve suddenly being closed they needed a bypass valve fitting to ensure when this occurred the pump was not damaged.

We selected our NRBAL Rotary Vane Pump fitted with a heating chamber and bypass. A heating chamber can be oil, water or electrically operated and prevents solidification of liquids which harden when cooled.

The heating fluid circulates through the back of the casing ensuring the internal temperature is maintained within the unit. Pumps which handle material which solidifies are usually fitted with a packed gland which is not susceptible to damage should material harden in the sealing area.

As the unit was from our Vane pump range, we offer an accelerated production schedule upon request, with our pump built and delivered to site within 3 working weeks.

Vane pumps are volumetric pumps meaning flow is proportional to speed, enabling the customer to predict flow rate regardless of discharge pipework losses. They are also largely unaffected by changes in viscosity which may occur during differing batches.