Investigating load shift potential through the use of off-gas holders on South African steel plants

Several by-product off-gases are produced in the steel making process. These off-gases can be burned to provide thermal energy which has various applications on a steel plant. As a result, steel plants capture these gases and use them for heating applications. One such application is in the boilers, where steam is produced. In turn, this steam can be used in turbines to drive alternators and generate electricity. In many cases, steel plants have storage vessels for the off-gases linked to the gas distribution network. These containers are primarily used to stabilise the pressure of the gas in the network. However, the capacity they provide can also be used to increase steam production for electricity generation during peak periods. This approach is investigated in a case study through the simulation of a South African steel plant. The plant is investigated and operating constraints are considered in the simulation model. The simulation shows that 2 MW of additional generation capacity can safely be shifted into Eskom peak periods, saving the steel plant R2.3-million per annum.