2 replies to this topic

[Arsal]

We have a box type and cylinderical heaters at different processing units.all the heaters are natural draft.heater efficiency is also around less than 60 % and fuel consumption is so high.I have some questions regarding the upgradtion of these heater.

 

1)Is replacement of natural draft heater with forced/balanced/induced draft gives good efficiency and fuel saving?

2)Is waste heat of stack gases may used for making of MP steam By installing waste heat boiler?

3)which Modern upgradation methods is used to improve heater efficiency?

4) is air preheater plays important role in heater efficiency?(we dont have an air preheater)

5)if we replace natural draft heater with some induced /forced draft then it will make us for benefical or not?

 

Your valuable tecnical feedback is required.

 

Thankyou.

 

 

 

[Zubair Exclaim]

Arsalan

 

You cannot simply change the design from natural draft to forced draft just like that. Natural draaftt heater is not designed tto accomodate forced draft and vice versa.

 

1-Yes waste heat recovery by using steam generating waste heat boiler could enhance efficieny

2-preheaters improve efficiency exponentially but are economical for big heaters

 

Overall heater analysis need to be carried out evaluating radiation box performance convection box performance etc, exhaust gas characterstics ....

[pankaj.cheresourses]

Hello Mr Rao,

 

Please find point wise answers against your questions listed below:

 

1)Is replacement of natural draft heater with forced/balanced/induced draft gives good efficiency and fuel saving?

Ans : Heater type (i.e. Natural/Balance/Induced draft) is not having any direct correlation with heaters efficiency/fuel saving.

 

2)Is waste heat of stack gases may used for making of MP steam By installing waste heat boiler?

Ans: Of-course, based on the type of fuel you are firing (Sulfur content) and delta available (i.e. outlet flue gas temperature-Acid dew point) and space available in convection section for future rows ( may be 2 to 3 rows) you can generate steam as a utility.

 

 

3)which Modern up gradation methods is used to improve heater efficiency?

Ans : there are various aspects by which you can improve heater efficiency examples good operational parameters ( an appropriate air/fuel ratio, using preheated air etc.)

 

4) is air preheater plays important role in heater efficiency?(we dont have an air preheater)

Ans: Yes, air preheater plays important role to boost heater efficiency but it will also increase capital investment (almost more than 1.5 times) and if preheated temperature increases beyond certain limit their would be chances to increase NOx level.

 

5)if we replace natural draft heater with some induced /forced draft then it will make us for beneficial or not?

Ans : The maximum efficiency which you can achieve by using natural draft furnace is ranging up to 80-85 %, and by using the balance draft or other configurations you would be able to achieve 92-94% (Max, even it depends on fuel you are using). Simultaneously you will need lot of capital investment as well. (even heater firing capacity also governs this, as you should't install balanced draft furnace for small heaters of 10 MW or so).

 

Revert me, if you want any further clarification.

 

Regards,

Pankaj