PTC 4.1 issued in 1964 and reaffirmed in 1991 was superseded and withdrawn in 1998 to be replaced by a new code PTC 4 that corrects many deficiencies of PTC 4.1 and makes the testing more accurate. However, PTC 4.1 in many parts of the world continues to be fol­lowed. Table 1.7 shows the essential […]

The principle behind calculation of efficiency is as follows: • Losses 1a, 1b, and 2 are calculated from test results. • Loss 3 is read from ABMA chart. • Loss 4 is agreed before the test. For calculating Lub (loss 2) in the case of PF-fired and FBC boilers, the ash distribution between fly ash […]

Heat loss (or indirect method as per BS) is 1. Practical because it calls for no flow measurements to calculate efficiency 2. More accurate because it involves measuring only the loss and not the efficiency In measurement of any loss, the sensitivity of any inaccuracy is considerably reduced on the final result. For example, in […]

This (or direct method as per BS) is a simple method for calculating the efficiency, which gives an approximately correct value, but with a wide tolerance. It is good enough to reveal the general picture routinely in small-to-medium oil — and gas-fired boilers, which use fuels with nearly constant CV levels that are amenable to […]

Heat balance and performance testing are final steps of boiler implementation. The final act of performance testing is followed by taking over of the plant by the owner and final finan­cial settlements. The warranty period of the boiler commences thereafter. Therefore, it is very important that the testing procedures are conducted impartially to avoid expensive […]

For a hypothetical stoker-fired boiler, the efficiency calculations are as given in Appendix A. Any efficiency calculation has the following two parts: 1. Combustion calculation 2. Estimation of loss account to arrive at the efficiency by difference Using the efficiency figure, the fuel fired and fuel burnt can be estimated, which paves the way for […]

Gross efficiency of boiler = 100 — (% Loss 1 + 2 + 3 + 4) (1.3) Where 1. Stack loss consists of A. Dry gas loss (Ldg) B. Moisture loss (Lm) C. Humidity loss (Lh) 2. Unburnt loss (Lub) 3. Radiation loss (Lr) 4. Unaccountable loss (Lu) Stack Losses These are measures of 1. […]

Ambient conditions, namely temperature, humidity, altitude have an important role in determining the efficiency of a boiler and the sizing of auxiliaries. • Stack loss, which constitutes —70-80% of the total loss, is measured with ambient temperature as the datum. The efficiency would therefore appear to be lower by —0.25% for each 5°C increase in […]

Like any other equipment, a boiler has to be configured and operated at the optimum efficiency—a function of the fuel and interest costs. As the fuel costs have increased, the boilers have also improved in their efficiency. In gas-rich countries, for example, GTs still operate on open cycle with no HRSGs to recover the heat. […]

Figure 1.4 depicts the energy balance in a boiler showing the fuel and air energy inputs and steam energy outputs from both SH and RH and the various losses are shown in Table 1.3.