Dear Mr. Vishy,

The material properties of the Flue Gas Disulfurization Gypsum determine the transport possibilities.

If the gypsum is dry and the particles are in the range of 20 micron to 150 micron, a pneumatic conveying installation is a good option.

In your thread, you are not considering this option.

If the required conveying rate in combination with the transport distance makes a pneumatic conveying system not feasible, then there is always the solution of bulk truck pressurized tankers (road mobile or railway wagons)

The obvious advantages of a pneumatic system are dust free, automatic and no labor involved.

If you can tell us more about the gypsum hoppers and the transport layout with distances and silos, a more to the point answer can be given. ■

FGD product & Fly Ash are similarly produced in coal fired power plants and they are transported some distance for further processing.

Anil Seth & Balan Velan are well versed in the Indian scenario.

It has been stated in previous posts that tubs (pressurised powder tankers) are not readily available in India & distances can be considerable.

Bag-in-Box (lined containers) is often proposed despite the silly drawbacks involved. Liners are costly and despite promises they are generally

discarded. Containers chosen are usually 30 footers with a letterbox rear opening which renders them highly specialised and useless for return

purposes. Some 'clever ' manufacturers also provide top filling which means that there must be more seals for intermodal transport with the tedious

process of extra documentation & access to check those upstairs seals. I have driven bag-in-box & I always envied the guys driving tubs, but tubs are

rare in India.

In Europe there is little difference in the high overheads of bag-in-box versus tubs, both have to be returned empty.

It will be very difficult to keep gypsum dry in monsoons so open trucks, road & rail (covered or not) will be uneconomic due to rejected deliveries.

The overwhelming advantage of containers is safe containment. If consignments are properly balanced there is no need for storage buildings at either

end. If standard 20 footers are used there is no return problem with delay or supply.

Since you auto suggest road transport for local distribution & rail for interstate then your better option is 20 foot standard unlined containers

which you can load & forget about.

If you need guidance on the filling & handling methods my details are below. ■

John and I did not directly answer this question.

I was opting for pneumatic bulk tanks (road mobile or railway) and John is in favor of tubs.

John ‘s option for 20 feet standard containers is also asking for loading equipment and a way of unloading. (For which installation information is offered by John at his website and e-mail).

Overloading a 20 ft container with gypsum must be prevented.

Back to the original question “generally a rectangular type or hopper type”, I would say a “hopper type for better and easy unloading by the hopper”.

A “box type” has flat bottom and should be unloaded by tilting over or cleaned out by sweeping.

NPTC Ltd. Is known as “India’s largest power utility with an installed capacity of 55,786 MW”

I assume that the company knows “how the horses run”. (Dutch saying) ■

For clarity: tub is the operational trade term for a pneumatically (assisted) unloaded tank whether rail or tyre mounted.

A preference for standard containers was intended to express a very definite choice & still does. A modifier to this is that either 20 or 40 footers can be used. When it comes to loading & unloading material the open topped railcar is simpler to load but not so simple to unload & if a car tippler is required for every customer the CAPEX requires a lot of justification. Hopper cars require either a ground hopper or a crazy little tuck under gadget which must be closely fitted between the rails & the hopper outlet. So, open topped boxcars are not preferred because there are probably multiple customers. Hopper cars are somewhat non-preferred because they might not be always available. Both of these systems rely on the weather & will be exposed to monsoons for a substantial time. Dumping dry gypsum into wet open topped cars is not going to encourage discharge under any circumstances.

Containers have drawbacks as well. European trailers adapt to all container sizes but they are sophisticated machines not available outside Europe. I know this from dealings with aspiring Chinese trailer manufacturers who are amazed, inquisitive & looking for a free design. This latter situation was a major reason for closing my website down.

It is only sensible to examine 40 & 20 footers carried on rigid chasses, rail or road. Whilst these boxes can be tipped over the edge, they still require crane involvement. Your customers would have to decide whether to hire in a mobile 20t crane or install a portal crane. This assumes that they have seen the light on wagon tipplers. Some of them anyway. Simple attachments are readily available to facilitate tipping in either stuffing & stripping operations for both rail & road transit.

Forty footers do not need as much dunnage as 20 footers & 70% of the world’s fleet is 40’s. The dunnage requirement is explained in a previous post of mine, which nobody took the trouble to read. In similar vein the earlier illustrations concerning twist-lock arrangements, drive through loading & unloading were also systematically ignored. But they are still there somewhere. Proponents of containerisation for bulk handling have occasionally requested a dedicated forum for this activity: but to no avail. This is very regrettable but I don’t let it interfere with my Android programming activities anymore. ■

John,

How a simple question from Mr. Visha can lead to a complex consideration about transporting gypsum.

As each design has its own merits, the container solution with tipplers or the solution with tubs are preferable.

Although the pneumatic conveying solution in the humid environment requires at least conveying air drying and the container solution is guaranteed condensation free, if unloaded inside a confined space.

Still, this depends on the volumes and distances and the storing facilities at the receiving end.

NPTC Ltd. has a lot of designing and evaluation to do. ■