What Are the Key Challenges in Using Vertical Retorts for Coal Distillation?

[brispuss]

This is regarding vertical retorts, specifically those used in "distillation" of coal to produce coal (town) gas, tar and other by products.

It is understood that the distillation of coal is done by heating coal in an air (oxygen) free container (ie in a retort).

The vertical retort is, apparently, a fairly large vertically oriented open topped cylinder with a narrowing body at the bottom of the cylinder to form a relatively small opening to allow discharge of coke (and some tar).

Now, with regard to a "continuous" feed vertical retort, it is understood that coal is loaded into the top of retorts, and as it makes its way down the retort under the influence of gravity, the coal is converted to coke while the retorts are heated (using coke, gas, or oil fuel as the heat source). And the size of coke produced is maybe slightly smaller than the coal. So coke is still a fair sized "lump".

There are several questions regarding this process.

1) How is the continuous feed of coal achieved in an air (oxygen) free environment? If air (oxygen) is admitted to the retort, surely the coal would burn instead of being broken down by distillation(?)

2) Small lumps of coal would presumably fall straight through the retort without being distilled(?) So how is coal prevented from falling through the retort without being "processed" first?

3) The narrow(ing) discharge at the bottom of the retort would surely tend to cause clumping of coal/coke and prevent discharge(?) So how is this overcome?

 

[anorlunda]

I can't answer all your questions. There are lots of variations. But in this article https://en.wikipedia.org/wiki/Coal_gasification#Process they briefly discuss direct blowing, rerverse blowing, and pressurized fluidized beds. Also, consider that there are flows of coal, oxidizer and steam to consider.

Removing coke might be done like removing flyash from a wet bottom coal furnace. But that's just a guess.

You need a lot more detail about the specific plant before all those questions can be answered. Do you have access to any of the plant's engineers to talk to?

 

[brispuss]

Thanks for the comments.

I do not have access to any "engineers" who may answer these questions, otherwise I would have done so already and probably would not have started this topic.

I've looked on the internet (including Wikipedia and other sites) but have yet to find the information I'm wanting.

There is no specific make or brand of vertical retort in mind. Although the detailed procedure of processing coal into coke, gas etc may vary a bit between brands of vertical retorts, it is assumed the basic process procedure would be similar between the retort brands.

These three questions should really be answered by someone familiar with the operation of vertical coal distillation retorts. Guesses are not really helpful, facts are what is required please.

Thank you.

 

[Asymptotic]

The first iteration of manufactured gas technology S-curved and peaked between the late 1800's through early 1900's, and you might consider researching books written then, for instance, The United Coke and Gas Company volume, "A Short Treatise on the Destructive Distillation of Bituminous Coal", or Google Books scans of the Gas Journal.

These three questions should really be answered by someone familiar with the operation of vertical coal distillation retorts.

Good luck with that. Try tracking down engineering personnel at experimental synfuel plants, but I'm not aware of any extant commercial producers of town gas.

 

[brispuss]

Thanks for the comments.

By chance I can across some information on vertical retorts within a scanned copy of an early publication. And although the scanned text describes the general process of distilling coal within the vertical retort, it doesn't go into quite enough detail, unfortunately. So my original three questions remain unanswered.

This early publication refers the reader to (numerous) other publications for further information on vertical retorts, but the publication does not cite any specific publications.

It is realized that most town gas plants (worldwide) have ceased to exist for several decades. However, there may still be someone who worked at a plant who could provide answers. Alternatively someone who has already researched vertical retorts could (also) provide answers?