B.E., M.B.A.,M.M.M., M.F.T., M.Phil., (Ph.D)

Sr. Manager (Steam Engineering Applications)

Forbes Marshall Pvt Ltd Coimbatore

Email: rajarajan@forbesmarshall.com

In every processing industry, steam heating is a heart of the plant. Without which, every thing in the plant would be in a standstill condition. In authors experience, many processing plants in India, we have observed that customers have been sizing the boiler and pipe lines with the bench mark of neighbors/close knitted group of people and also contractors suggestion.

In reality, either the boiler would be running half of the boiler capacity because of over design or starvation of steam because of under design during the plant operation. This is the really scenario prevalent in the textile process industries. If we analyze the root cause of the problem, we came to know that it could be any one of the following:

• Boilers and Piping have been designed on the assumption that the client would go for expansion. But would the expansion occur within one year or two year or after five years. Only about 10 to 20 % of customers have a clear plan for expansion and balance 80 of customers were not having any clear policy for future expansions and these are all subject to the market demand and supply. In light of market murkiness, Can we design the utilities based on the current requirement with 30 % cushion for expansion?
  

• In light of the over design of energy equipments, the piping radiation loss has been considerably very high and capital cost also high.
  

• We also observed that many customers size the boiler based on the processing machines maximum temperature gradient and not being designed on the average temperature gradient.
  

• For example, certain soft flow machines where the temperature gradient for scouring cycle may be 9 deg/min and rest of cycle like dyeing may be 2 to 3 deg /min and hot wash and soaping gradient may be 4 deg/min. In fact, the machine and fabric temperature itself in the range of 40 to 50 Deg C. Where as customer take the gradient of 9 deg/min for boiler sizing and end up with operating the boiler less than 50 % of the boiler capacity. As a result, boiler efficiency would go down to the tune of 55 to 60 %. Because of lower efficiency of boiler, there would a reduction in steam fuel ratio from 1 : 4 to 1: 2.5 ( Wood Fired Boiler ). I
  

• If we calculate the total steam loss for a boiler capacity of 6 TPH wood fired boiler (Assuming the boiler efficiency is 55% because of 50 % load in the boiler ) and actual steam production is 3 TPH.. Total Running Hrs: 8000 Hrs per year.
  
  
• The approximate wood consumption per hour for 3 TPH would be around 800 to 900 kgs while the total steam loss on account of lower steam fuel ratio (1: 4 to 1: 2.5) 1.5 kg steam loss per kg of wood. The total steam loss for 900 kgs of wood consumption: 1350 kgs per hour and steam cost for wood fired boiler: Rs.0.80 per kg (Including wood, power and labour charges). Total loss on account of lower steam fuel ratio per hour : Rs.1080. The total yearly loss: Rs.86 lacs. This is really a mind boggling figure to all of us but it is a fact in all textile processing mills.