Purging Hazardous Material
If centrifuges are used to process products whose vapors together with oxygen may form a flammable suspension, any risk of explosion must be avoided by substituting air with inert gas. Generally, nitrogen is used. Centrifuges and system components used for the processing of hazardous materials have to be gastight to prevent the exit of vapors into the atmosphere as well as to avoid the entry of air into the system. Typical examples are processes in the chemical, petroleum, and pharmaceutical industries, or processes with flammable organic solvents or those involving oil sludge treatment. These centrifuges comply with ATEX 95 in Zone 1 or Class 1, division 1, up to temperature class T3.
Before starting, the entire system, including the centrifuge, is purged. In order to do this, large volumes of inert gas are flushed through the system until the amount of oxygen is reduced to a non-critical and safe level. Purging is complete if the amount of inert gas delivered to the system reaches a multiple of the system volume, or if an oxygen probe at the centrifuge housing shows a safe oxygen concentration.
After successful purging and during operation with the product, sufficient inert gas is fed into the system to ensure a small overpressure. This prevents atmospheric air from penetrating into the system.
Control of Centrifuge Purging with Inert Gas
This accomplished with a differential pressure monitoring system with integrated automatic control. Thus, a fixed overpressure in the sealing system is constantly maintained using control valves. Manual readjustment is not required anymore. This method ensures a small overpressure within the sealing system and the inside of the centrifuge guaranteeing protection against air leakage into the system and product emission into the atmosphere.
Processing of Materials Susceptible to Oxidation
In particular, processing beverages and food requires that the product is prevented from undergoing oxidation. For this purpose, the leakage of air into the centrifuge is prevented with relevant design features and the centrifuge is purged with inert gas. In many cases, carbon dioxide is used as inert gas. A system monitoring the flow of gas is commonly used.
The motivation for processing drilling mud, drilling emulsions, and drilling fluids is easy to understand: on oil platforms, in tunneling, or in other industrial sectors where drilling systems are applied, continuous cleaning of these liquids is crucial in order to guarantee and enhance the optimum processing of the drilling systems. Furthermore, constraints and requirements regarding the environment (pollution of groundwater and seawater) are getting stricter, requiring continuous treatment and separation of drilling mud, fluids, and emulsions.
Drilling mud has to fulfill multiple functions: It has to lubricate and cool the drill head and carry the bits of rock and detritus away which are cut off. Drilling muds are based on water, oil, or polymer along with various additives such as stabilizers, flocculants, corrosion inhibitors, defoamers, surfactants, detergents, lubricants, and more. Modern drilling systems form a closed cycle from which no solids are able to escape. As a result, any particle which gets into the closed system has to be separated. Shaking screens and hydrocyclones can separate out coarse particles, but a G-Centri-Force Decanter separates small and fine particles. For a better overview and understanding of how drilling mud, fluids and emulsions are separated and processed using a G-Centri-Force Decanter, please have a look at the process scheme below.
G-Centri-Force DG series drilling mud decanter centrifuges are designed specifically to remove unwanted solids and fine particles from virtually all kinds of used drilling mud, including those based on water/synthetics and conventional oil-based drilling fluids.
Built for heavy-duty processing, a DG installation handles large quantities of solids in the feed flow, as well as being able to cope with coarse, abrasive particles. It also efficiently removes the vast majority of fine particles, down to sizes of around 5 microns. Traditional equipment is unable to deal with these particles, which have a serious impact on the quality of drilling mud because of their abrasive effect. The G-Centri-Force DG series decanters have been designed for the best available wear protection in the market.
A DG installation can pave the way to dramatic reductions in drilling mud costs because less mud is wasted. Being able to remove solids in very dry form also means lower costs for transporting and disposing of solids waste. Additional savings stem from opportunities for automatic, unattended operation, and from the extended service life of DG installations due to their exceptional reliability. The machines have been designed for reduced power consumption in relation with process flow.
Optional modules are available to match DG set-ups to specific needs encountered on drilling rigs. These include both fully automated modules and relatively simple manually operated modules that together provide cost-effective solutions to all solid’s separation requirements.