Ipsen HybridCarb reduces process gas costs for gas carburisation by a factor of ten

The costs of process gas and the preventable emissions when case hardening metallic components are reduced by a factor of ten as soon as the new patented HybridCarb process for gas carburisation from Ipsen is used. This means annual savings of up to 25,000 euros per furnace for heat treatment plants due to the significant reductions in gas consumption alone. The newly developed HybridCarb system is not just suitable for new systems but can also be retrofitted on existing furnaces.

Every heat treatment process involving the gas carburisation of steel components uses hydrocarbons. Generally, natural gas or propane is used for this process. The hardness of the case achieved by this process, in turn, plays a major role in deciding the durability of the steel components. For example, gearbox components for wind power systems must be extremely durable since these are designed for a service life of 40 years. After all, many wind parks are located 100 kilometres away from land in the North Sea where repair work with a floating crane and a helicopter can cost in excess of EUR 10,000 per hour.

Conventional technology
Large quantities of gases which contain hydrocarbons (for example natural gas) are fed through furnace chambers at temperatures of up to 1000°C in everyday practice in a heat treatment plant. The hydrocarbon bound in the gas diffuses into the surface of the workpieces and thus provides the basis for good surface hardness. However, after a brief dwell time in the heating chamber, the entire volume of gas burns off in controlled conditions outside the furnace and is therefore rendered useless after a very short time. The throughput varies depending on the size of the furnace and may be around 16 cubic metres per hour in a size 17 furnace (charge dimensions (W x L x H) 910 mm x 1220 mm x 910 mm). Very small quantities of the hydrocarbon contained in the gas are actually used to increase the case hardness properties, however. The vast majority of around 97 percent of the gas is burned off without being used. As a result of this, the efficiency of the process is around two to three percent.

Progress thanks to HybridCarb from Ipsen
Ipsen International has now developed a method of radically improving this efficiency level. The new process is called HybridCarb with which Ipsen now feeds almost the entire volume of gas from the furnace through a treatment chamber to recycle it rather than simply burning it off in a flare. Using the patented Ipsen principle, the mixture of gas is enriched in the protected hybrid process with additional gas and then returned to the furnace. The principle is distantly related to the sealed circuit of a central heating system in which the water used to heat the radiators is not simply discarded as soon as it has passed through them.

The entire process in the heat treatment furnace is extremely simply to control using a typical Ipsen system controller to ensure good, precisely reproducible quality of the carburisation process. Overall, the efficiency of the carbon transfer process and therefore the use of the carbon is increased palpably from its former level of just two percent to as high as 20 -25 percent when the furnace is fitted with the HybridCarb system. The volume of process gas used falls by a factor of ten – as, of course does the cost.

Thus on the basis of annual emissions from a typical furnace of around 65 tonnes of carbon dioxide, a reduction by around 58 tonnes per year to around ten percent or just seven tonnes can be achieved. For gas carburisation alone, this means that the HybridCarb process will produce annual cost savings of up to 25,000 euros per furnace. At the same time, the extreme reduction in the consumption of natural resources also represents a massive step forward towards the modern, cautious use of resources.