Efficiency in Boiler Feed Pumps for Industrial Steam Generation

This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows： 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are： the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as： impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three

Energy Efficiency Classification for Agricultural Heater

Classification of energy efficiency system for agricultural heater was discussed and analyzed in order to derive an energy efficiency classification scheme for agricultural heater. Current practices of energy efficiency programs for other products such as residential gas boiler were investigated and analyzed. Test items including energy efficiency and standby power for agricultural heater were analyzed. With the data of residential gas boiler, grade distribution of energy efficiency system was made and evaluated. An energy efficiency classification scheme for agricultural heater was proposed and applied to agricultural heaters, and the scheme was justified. Introducing a new energy efficiency classification system to the agricultural heater industry, it is expected that considerable amount of fossil fuels can be reduced by adopting energy efficiency classification system.

Experimental simulation of the relative contribution of volatile-N and char-N to NO_X formation from a low-capacity bituminous coal-fired industrial boiler

The conversion of fuel-N to NOx is the main contribution of modelling problem arising from coal combustion. This paper NOx from coal-fired industrial boilers and is the least-studied summarises the current understanding of the mechanisms that account for the formation of NOx from fuel-N during coal combustion. Further experimentation on NOx emissions during bi- tuminous coal combustion was simulated with attention focused on the contribution of char-N and votatile-N to fuel-NOx through the Coal/Char combustion method. The critical analysis of this issue allowed for the identification of uncertainties and produced well-founded conclusions. The results indicated that fuel-NOx formation was a very complex physical-chemical pro- cess involving many competing mechanisms. These mechanisms included chemical reactions, convective mass transfer, heat transfer, adsorption and desorption. The contribution of char-N in this experiment varied between 30% and 70%. There may be a slight question as to the exact identity of the main contributor to fuel-NOx, and no definitive conclusion can be made as of yet This uncertainty is because the contribution of char-N to fuel-NOx was heavily affected by the combustion conditions and the contribution of char-N increased monotonically as temperature increased. There was a critical point in the relationship between particle size, air flow, 02 concentration and the contribution of char-N. The contribution of char-N increased with the increase of particle size and air flow initially when less than the critical value, and decreased when more than thecritical value. The contribution of char-N initially decreased when the 02 concentration was increased from 10% to 15% and increased more with the further increase in 02 concentration.

对编制一九九○年不变价格的原则、方法的建议

由于生产发展和价格的变化,不变价使用一个时期以后就应进行修订,否则会给计算发展速度带来不利影响。1952、1957和1970年的不变价与现价相差2~13.2%时,就及时编制了新的不变价。而1980年不变价格已经使用了9年,据1989年初步计算,现阶比不变价已高出40.8%,这必然会给计算发展速度带来一定误差。因此,必须在近期内编制出1990年不变价格。不变价格工业总产值是实物量指数的性质,以及这一指标的作用决定了编制不变价格的原则。不变价格是计算不变价格总产值的手段,因此。