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#BoilerManual #AirAndGasFlow #Section3 #Page29

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Alt = Labeled Fig. 22 Effects of gas recirculation. Image is sideways with the bottom along the right edge and the top along the left edge. It is an image of two simlified drawings of a boiler furnace with arrows indicating direction of gas flow. the drawing on the left is marked "Gas flow without gas circulation" and the one on the right is marked "Gas flow with gas recirculation". The drawing on the right has two additional arrows drawn pointing up in the cyclone bank firebox, drawn thickly, and the arrows are marked Gas recirculation. On the penthouse at the top of the left drawing, two thin arrows are marked Convection heat. In the corresponding area of the drawing on the right, one arrow is added and the arrows are marked Convection heat increased.

#BoilerManual #AirAndGasFlow #Section3 #Page29

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Alt = Labeled Fig. 22 Effects of gas recirculation. Image is sideways with the bottom along the right edge and the top along the left edge. It is an image of two simlified drawings of a boiler furnace with arrows indicating direction of gas flow. the drawing on the left is marked "Gas flow without gas circulation" and the one on the right is marked "Gas flow with gas recirculation". The drawing on the right has two additional arrows drawn pointing up in the cyclone bank firebox, drawn thickly, and the arrows are marked Gas recirculation. On the penthouse at the top of the left drawing, two thin arrows are marked Convection heat. In the corresponding area of the drawing on the right, one arrow is added and the arrows are marked Convection heat increased.

#BoilerManual #FluidCirculation #Section2 #Page29

When the change of temperature between furnace circuits is less than 80 F and the unit is operating at the correct pumping and firing rates, a good fluid mix is said to exist. These conditions greatly reduce the risk of a tube failure in the furnace circuitry. See Figure 23 for a temperature comparison with and without the furnace mix system.

Convection Pass

The roof outlet header is joined by interconnections to the convection pass supply downcomers (one on each side of the unit). These downcomers travel down the length of the horizontal convection pass (CP) and supply three areas: the pendant CP floor inlet headers (which also forms the arch), the pendant CP side wall headers, and the horizontal convection pass enclosure headers. Let's examine each of these circuits in more detail (Figure 24).

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Alt = Labeled Fig. 23 Temperature comparison with and without the mix system. Two graphs are shown, each with the y axis incrementing in 100 degree F increments from 600 to 1000 F lines. The x axis increments are shown only on the bottom graph with the expectation that they be applied to the upper graph which aligns with it--in terms of percent of furnace height, increasingly incremented in 20% marks. top graph is labeled WITHOUT MIX; the bottom one is labeled WITH MIX.
The top graph plots out a solid line labeled Average, and a dotted line above the solid one and the area between the two lines is shaded and labeled Upset. The bottom graph depicts the same scheme but plots out a solid line across the entire graph and labels that line 2nd pass average. A shorter solid line under that is labeled 1st pass average, and where that line terminates along the x axis, the remainder of the 2nd pass average line is labeled 3rd pass average.

#BoilerManual #FluidCirculation #Section2 #Page29

When the change of temperature between furnace circuits is less than 80 F and the unit is operating at the correct pumping and firing rates, a good fluid mix is said to exist. These conditions greatly reduce the risk of a tube failure in the furnace circuitry. See Figure 23 for a temperature comparison with and without the furnace mix system.

Convection Pass

The roof outlet header is joined by interconnections to the convection pass supply downcomers (one on each side of the unit). These downcomers travel down the length of the horizontal convection pass (CP) and supply three areas: the pendant CP floor inlet headers (which also forms the arch), the pendant CP side wall headers, and the horizontal convection pass enclosure headers. Let's examine each of these circuits in more detail (Figure 24).

------------------------------------------------- 29 ------------------------------------------------------
Alt = Labeled Fig. 23 Temperature comparison with and without the mix system. Two graphs are shown, each with the y axis incrementing in 100 degree F increments from 600 to 1000 F lines. The x axis increments are shown only on the bottom graph with the expectation that they be applied to the upper graph which aligns with it--in terms of percent of furnace height, increasingly incremented in 20% marks. top graph is labeled WITHOUT MIX; the bottom one is labeled WITH MIX.
The top graph plots out a solid line labeled Average, and a dotted line above the solid one and the area between the two lines is shaded and labeled Upset. The bottom graph depicts the same scheme but plots out a solid line across the entire graph and labels that line 2nd pass average. A shorter solid line under that is labeled 1st pass average, and where that line terminates along the x axis, the remainder of the 2nd pass average line is labeled 3rd pass average.