{"id":6240,"date":"2009-09-10T13:39:29","date_gmt":"2009-09-10T11:39:29","guid":{"rendered":"http:\/\/inercomunicacion.com\/?p=6240"},"modified":"2018-05-24T13:18:55","modified_gmt":"2018-05-24T11:18:55","slug":"improve-efficiency-of-furnaces-and-boilers","status":"publish","type":"post","link":"https:\/\/inercomunicacion.com\/en\/improve-efficiency-of-furnaces-and-boilers\/","title":{"rendered":"Improve efficiency of furnaces and boilers"},"content":{"rendered":"

Novel’ control’-scheme optimizes operations and reliability of combustion units.<\/strong><\/h3>\n

New technologies enable optimizing combustion processes for hydrocarbon processing facilities. Economic and environmental drivers require improving operating efficiency while mitigating emissions of carbon dioxide (CO2<\/sub>), nitrogen oxide (NOx)’ carbon monoxide (CO) and particulates. “Smoother” operations increase the safety for combustion units.<\/p>\n

In the following case history, a Spanish refiner applies a novel combustion control technology to the crude oil furnace. The article describes the overall technological approach and the latest results, regarding combustion efficiency improvement (overall CO2<\/sub> emissions reduction) and parallel effects in NOx emissions control, through the implementation of a novel combustion control technology to a crude oil furnace of a Spanish refinery.<\/p>\n

Project goals included reduced CO2<\/sub> and NOx emissions with better reliability.<\/p>\n

Background. Combustion improvement offers the greatest potential for economic savings regarding the operation of industrial boilers and furnaces. Nevertheless, the combustion process is opaque from the operator’s point of view. For this operating unit, fuel costs are the greatest operating expense; yet, how this fuel is utilized remains unclear.<\/p>\n

Despite the economic and environmental importance of combustion processes, these operations involve a low level of monitoring and control. These processes are governed by a few global variables such as excess oxygen (O2<\/sub>) or process stream yields, with no direct control of combustion conditions.<\/p>\n

Furnace or boiler operations are supported by standardized procedures and operator experience, rather than by effective online information and optimized flame control. Moreover, in most cases of multiburner application, standard monitoring applied for global excess O2<\/sub> control in the combustion unit does not represent the true average excess O2<\/sub> value at the furnace level, thus introducing a critical restriction when trying to optimize tuning of combustion conditions.<\/p>\n

This situation heavily contrasts with the current stare-of-the-art level of most industrial processes, in which comprehensive monitoring and advanced control systems ensure process safety, plant availability and maximum efficiency. It is surprising that a chemical process such as combustion, with an impressive economic and environmental impact worldwide, still relies on nearly archaic controls.<\/p>\n

Recently, considerable attention has been directed to combustion adjustments for efficiency optimization and emissions limitation. Nevertheless, the cost-effectiveness of these adjustments is limited by mentioned restrictions over combustion monitoring and control. This gives rise to the erroneous decision to upgrade the burner system without first attempting to optimize the present combustion system.<\/p>\n

This situation is even more relevant in scenarios with high variability in fuel properties, loading profiles and\/or burner arrangements for multiburner systems. In these cases, uncontrolled combustion conditions may force operators to apply “too conservative” boiler settings and to move away from optimum tuning.<\/p>\n

Controlled furnace technology. <\/strong>Efficiency and emissions (NOx’ CO, CO2<\/sub>, <\/em>particles, SOx, etc.) in industrial furnaces and boilers depend largely on the correct distribution of fuel and air supplies to the combustion process. Moreover, inappropriate fuel\/air ratios on critical locations severely impact important furnace parameters (Fig. 1). Therefore, stricter combustion controls are a function to balance the combustion process.\"\"Combustion optimization technology relies on the adequate closed-Loop control of local combustion conditions, promoting what is called a “controlled furnace” (Fig. 2). This controlled operation is a critical factor to ensure the maximum benefits of combustion variables adjustment whose tuning directly impacts unit efficiency and NOx formation.<\/p>\n

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The controlled furnace approach enables individual optimization for any single burner. Result: Total optimization of the combustion process. This application improves unit efficiency and reduces CO or NOx emissions by applying specific optimization strategies in multiburner systems.<\/p>\n

Consequently, this approach is both a cost-effective alternative to implementing combustion-system modifications (burner substitution) and is an additional improvement tool if these modifications are finally installed. Also, installing this technology to an existing combustion unit requires minimum modifications to existing equipment and a shorter shutdown to install the associated new elements.<\/p>\n

As shown in Fig. 3, controlled furnace conditions involve an integrated approach and require:<\/p>\n