Question

Determine the height of chimney above grate level. Where diameter of chimney is 1.75m and produces a draught of 1.8cms of water. Temperature of flue gases is 290^oC. The flue gases formed per kg of fuel burnt are 23kg. Neglect the losses and assume atmospheric temperature as 20^oC?

(a) H = 23.28m

(b) H = 18.56m

(c) H = 32.77m

(d) H = 41.92m

I had been asked this question by my school principal while I was bunking the class.

This intriguing question originated from Draught System topic in portion Steam Generators & Accessories of Energy Engineering

Answer 1

Right answer is (c) H = 32.77m

To explain I would say: Given: D = 1.75m,

                                    Draught in mm of water = 1.8cm = 18mm

                                    Flue gas temperature = Tg = 290^oC = 563K

         Ambient temperature = Ta = 20^oC = 293k

         Flue gases formed per kg of fuel burnt: (ma + 1) = 23kg