Dear All
we have two Sulphuric acid plants operating in the same site ,one operates with a puller type blower meaning the blower is located downstream of the drying tower.The other plant operates with a pusher type blower wherein the blower is located ahead of the drying tower.I intend to change over the puller type blower to pusher type by relocating the ducts as the puller type blower impeller gets unbalance due to acid mist escaping from the drying tower.Has anyone of our forum members have a prior experience in doing such a changeover.

I anticipate the production can be increased as the drying tower exit air entering the furnace will enter at a reduced temperature as the heat of the compression will be rejected through the DT acid to the cooling tower circuit.Also i anticipate the drying tower pressure drop will reduce due to reduced velocity of gases through the drying tower as the pusher type blower will compress the atmospheric air and then send it to DT instead of sucking through it.
Shall be thankful if any of our forum members can share their experience or comment on such a changeover.

Avadiappan

Changing the position of the blower from Puller to Pusher will reduce energy recovery in the wASTE heat boiler as the heat of compression of air is not available and this heat goes into the acid cooling system which essentially is dissipation of heatto the atmosphere.
It is advisable to look into the reasons which cause acid mist to enter the blower and correct them. You should have a properly designed and operating mist eliminator. It is also important that the air at the inlet of the drying tower is clean and properly filtered free of solids which may blind the mist elininator. Your acid distributor also should be in good shape.
There are many plants operating with Puller blowers.In India, Coromandel fertilisers, GSFC, IFFCO , HINDALCO, STERLITE, have puller blowers in Sulphuric Acid Plants. Changing from puller to pusher will not have any advantage in the long term.
Changing the puller blower to to pusher without rectifying the problems in mist eliminator/distributor/air filter will probably give you the satisfaction that you are avoiding acid mist going to the blower. However,the same acid mist from drying tower outlet can still go into the plant and cause damage to other down stream equipment(boiler, converter, Economiser, HEs, etc) if the causes of acid mist in drying tower outlet are not identified and solved.
Any Way, It is your plant.Please do what you think is good for you.
V.V.Rao

The performance of DT will be the same as regards drying of air whether it is connected to a puller or pusher blower , same distributors and mist eliminatorsbeing the same. The internals are designed for operation at pressures above atmaspheric. I do not see how you will increase production by just changing to pusher. You can do the same with the puller too. The furnace temperature can go to 1200 C without any problem. The boiler should be able to cool the gas at higher inputs of Sulphur and air.There should be no problem in operating the plant with 11.5%SO2 with a puller blower. If you go above 11.5% SO2 and beyond the rated capacity(irrespective of a puller or pusherblower), you may get extra production with lower conversion effeciency .
V.V.Rao