Conversion of liquid phosphorus and liquid sulfur into a melt

Liquid phosphorus and liquid sulfur are converted into a melt, a raw material for insecticides, lubricant additives, and floating chemicals

Process

Molten phosphorus and sulfur are fed into a reactor via jacket-heated pipes where they react at a temperature between 300 to 400°C. The resulting melt from the reactor, phosphorus pentasulfide, passes along pipes to a cooling unit. These pipes are also jacket-heated to ensure the product remains in the molten state over longer distances until it reaches its destination. The heating must be very uniform since the temperature of the liquid phosphorus pentasulfide should be only slightly above the melting point. This prevents the pipe from becoming blocked because, as with a sulfur melt, the viscosity increases sharply just above the melting point and hinders the flow. Introducing nitrogen gas and increasing the flow rate also reduce the risk of pipe blockage.

Due to the highly corrosive environment, all parts in contact with the process, including the sensor, are made of Hastelloy® C22 or C276. Nevertheless, they are subject to wear so the operator must adjust the viscosity value weekly – to compensate for abrasion – and replace all components every two years.

Solution with Marimex® ViscoScope®

The ViscoScope® sensor is installed downstream from the reactor in a T-piece in the outflow pipe to ensure the sensor is in the middle of the flow. This also produces a “self-cleaning effect”, i.e. it prevents the build-up of residues on the probe. A riser (spacer between sensor flange and housing) with three cooling plates prevents the components in the sensor housing from overheating. No further cooling of the sensor housing is required.