MULTIPOINT THERMAL MASS FLOW METER OPTIMIZES REFINERY’S BOILER AIR- TO-FUEL MIXTURE RATIO FOR HIGHER OPERATING EFFICIENCY
The process and instrument engineers at a major oil refi nery
located on the Gulf Coast of the U.S. ran into several problems when they attempted to optimize their plant’s large primary boiler system. One of the major issues they needed to
overcome was better controlling the boiler’s burner air-to-fuel mixture ratio. The system’s air fl ow measurements were often inaccurate and erratic as well, which frustrated attempts to optimize the boiler’s effi ciency.
Like most boiler system designs, this one included a large, high capacity, air feed intake duct providing air to the boiler’s burner. The accurate measuring of the intake air fl ow rate is important to achieving the most effi cient mixture of air and natural gas at the burner in any boiler system. The more effi cient the air-to-fuel combustion ratio control, the less gas is consumed and with the least amount of off-gas, which reduces operational costs and the plant’s environmental footprint.
The Problem
The size and scale of this large boiler system’s primary duct limited the available fl ow meter technologies that the plant engineers could consider and the installation location itself was less than ideal. The air fl ow rate at startup also was substantially less than the fl ow rate during normal operation, which required an air fl ow meter with a high turndown ratio.
Additionally, the large air intake duct was only partially covered, which allows rain and dust into the duct. Furthermore, there are dense arrays of noise silencer tubes in the duct that restrict the installation of fl ow sensors to narrow passages between the tubes.
The refi nery had originally installed a multipoint differential pressure (DP) averaging fl ow meter. The DP meter’s reading, however, proved to be unreliable. The DP-bar had only a narrow turndown and the small orifi ces in the device were constantly fouling and clogging with dust particles, which resulted in excessive downtime and frequent unplanned maintenance.
Due to the size and scale of the ducting, its open to the elements construction and cramped layout, the choices of air/gas fl ow measurement sensing technologies was limited. In general the larger the diameter of a duct, pipe or stack, the more diffi cult it is to measure the air fl ow. Of the many technologies that measure air/gas fl ow, very few of them can operate accurately and reliably under these diffi cult conditions.
The energy cost of ineffi cient boiler burner air-to-fuel mixtures can be signifi cant. Ineffi cient operation of boilers in large refi neries can slow product throughput, affect product quality and increase costs. The process team at the refi nery needed to fi nd a better solution to its boiler problem, which eventually required looking at alternative fl ow meter technologies.
The Solution
The process and instrumentation engineering team at the refi nery contacted Fluid Components International (FCI) to consider an alternative solution. FCI’s local sales representative and applications engineering team recommended trying the MT100S Multipoint Thermal Mass Flow Meter (Fig 1).
The MT100 series is an insertion type multipoint fl ow meter specifi cally designed for large diameter pipes and large rectangular ducts, such as these air feed intakes (Fig 2), as well as stacks, fl ues, scrubbers and HVAC systems. These large pipe/duct applications
Fig 1. FCI MT100 Multipoint Flow Meter Refi nery Montage
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100
