Boiler House Expansion Under Fluctuating Off-Gas Availability

Abstract

It is not uncommon for engineering plants to generate steam from excess burnable off-gases. These off-gases are typically by-products from plants throughout the engineering Works. Steam is utilised all over the Works in various processes. If excess steam is available after the Works’ demands have been adhered to, energy recovery can processes can be invested in. A typical energy recovery plant comprises steam turbines for power generation. Depending on the nature of the process flows, the off-gas and steam availabilities may be of a fluctuating nature. This will inevitably result fluctuating power generation. This fluctuating power generation, however, may result in turbines shutting down involuntarily due to steam shortages. This furthermore results in power generation losses due to unutilised steam. In an attempt to address and power generation losses and turbine trips, boiler expansion was investigated in this paper. Off-gas flaring was simulated and analysed to determine what flow quantities of steam the plant could potentially additionally generate. The steam flows were incorporated within a power generation optimisation model to simulate the true effect thereof. From the results it was demonstrated for the engineering Works that additional boiler houses can be invested in. The results showed increase power generation; however, further simulations showed that boiler expansions should be coupled to turbine investments to fully capture the energy recovery available for the Works.