Boiler performance problems

Many mills bum this wood waste in boilers to obtain heat energy for process steam, and to alleviate possible solid waste disposal problems. These waste wood boilers are known as "hog-fuel" boilers. A base load of supplemental fuel of some kind is required in hog-fuel boilers, because the significant variations of the size, moisture content, and heating value of the wood waste may not allow consistent boiler performance. Supplemental fuel facilitates uniform boiler combustion, and ensures that a minimum amount of power is generated regardless of the fuel value of the wood waste at any one time. 

A positive result of TDF use in waste wood boilers is that facilities are able to bum sludge and waste wood more successfully, decreasing the likelihood of solid waste disposal problems. Results from a series of waste wood boiler performance tests using ASMS codes concluded that use of TDF supplementally in hog-fuel boilers enhances combustion of wood waste, and enables disposal of biological sludge in conjunction with wood waste without necessitating use of other fossil fuels such as coal.2 No applicable environmental limits were exceeded during these tests.2... 

Changes to biomass fuel quality as a result of changes in fuel source or from seasonal changes can result in unpredictable combustion performance in commercial boilers. This problem is compounded when the fuel supply changes significantly to a plant... 

The boiler efficiency and some data for a boiler are outlined in Problem 4.140. Depada-tion of performance and economic loss result from poor boiler performance. What are some of the steps you might take to improve boiler performance ... 

The inability to produce high-quality effluents is one significant disadvantage. Another disadvantage is that anaerobic processes must be maintained at temperatures between 35 and 40°C to get the best performance. If low-temperature waste heat is available from the production process, then this is not a problem. One advantage of anaerobic reactions is that the methane produced can be a useful source of energy. This can be fed to steam boilers or burnt in a heat engine to produce power. 

Problem A steam engine operates with a boiler temperature of 200°C. What is the maximum theoretical efficiency of the engine if operated on a warm summer day (+30°C) compared with a cold winter day (— 30°C) How much more fuel will be required to perform the same work in the former case ... 

Burning tires or TDF in a waste-wood boiler improves the performance of the boiler system. The high energy and low moisture content of TDF help stabilize boiler operations and overcome some of the operating problems caused by fuel with low heat content, variable heat content, and high moisture content. 

It would be difficult to define the ideal flue gas treatment system that would perform optimally for all boilers under all circumstances. However, given a boiler and its specific criteria, an optimal flue gas treatment system would possess as many of the positive aspects of the elements described above as possible. Research funding applied in this area to obtain this optimal system would be best spent by improving flue gas treatment system performance for as many boiler-site combinations as possible. Toward this end, processes that are most broadly applicable to problems currently associated with emissions control in coal-fired electric power generating facilities become important candidates for future research. 

The Consolidated Edison test results, as shown in Table VI, indicated complete suitability of SRC-II coal liquids as a high quality boiler fuel. No operational problems were encountered and no deposits were observed. Combustion efficiency was comparable to that for the low-sulfur No. 6 fuel oil, as were the levels of carbon monoxide and hydrocarbon emissions. Modifications to burner equipment required to handle the SRC-II fuel oil are considered to be no more extensive than those required for similar variations in petroleum fuels. Particulate emissions for the SRC-II fuel oil were generally lower than for the No. 6 fuel oil, and were in all cases below the new source performance standards proposed by EPA (0.03 lbs/MM Btu). 

Boiler Feedpump Drives. Second-Law techniques are applied to a practical problem determing when to drive feedpumps with electric motors and when to use steam turbines. This analysis was performed by Fehring and Gaggioli (40) for the Wisconsin Electric Power company. The Second-Law costing procedures are straightforward, avoiding the extremely laborious calculations associated with traditional methods, and/or avoiding the erroneous conclusions often drawn when those methods are simplified. 

Testing of the Shale-II JP-5 jet fuel, which is currently underway in four different gas turbine engines, shows good combustion performance. No problems have been encountered. Likewise, testing of ship steam boilers, marine gas turbines, and diesel engines on the Shale-II diesel fuel marine (DFM) is demonstrating highly acceptable performance. 

For the next 20 yrs no full-scale development work was performed in this area. In fact, during the mid-sixties, there were several steps backward when initial U.S. sulfur dioxide control systems started up and failed. For example, in the boiler injection of limestone followed by wet scrubbing, problems resulted from boiler and preheater pluggage rather than flue gas scrubbing. 

Since prehistoric times, it has always been true that, when you re building a fire, you watch it. In the era before furnace cameras, a performance engineer wearing a face shield had to open the boiler door (with the possibility of being burned) to spot problems, and radio the information to the control room. Continuous automatic remote monitoring using a camera is a much preferred procedure to opening a port. 

The empiricism that appears to follow the corrosion engineer arises from the multi-factor, multi-component situations which are present within all common articles of commerce, be they made from iron, aluminum, or more exotic material combinations. The variables are continually interacting in increasingly complex ways so we can become engrossed for even a lifetime with just one problem in performance such as airfoil stress corrosion cracking, boiler feed water stabilizations, or corrosion inhibiting paints, and many more. But does this mean the work lacks for glamour and excitement ... 

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