Abrasive and Impact Resistant Pipes for Ash and Coal Conveying

How about some of these, Guv:

• Conveyor belts?
• Shovels?
• Skip lorries?
• Railway wagons?

Without some idea of quantities I don't know what else to suggest.

You may want to do a Google search on ceramic lined pipe, and see what some of the vendors may have to offer. You may find some options to increase service life to 6 months or a year. Lined pipe will be more expensive, but you can determine the economics of higher cost vs. less downtime.

An option is to only line the areas with the most wear, such as elbows, so you're not paying to line the entire length of conveying.

I think I've mostly seen basalt lined pipe used for this service.

I used to work in the utility industry. One thing you may look at is Halar lined pipe. This stuff is like teflon, but better. its is a ETCFE. There is a company in Emmaus, PA Electrochemical Coatings that is one of the best for this. Ab-resist piping with other linings can work, but I have seen failures as well. Another company to check is United Conveyor, UCC in Chicago. They make a lot of lined pipe for this kind of thing. Be careful with what you pick. Check how they deal with the flanges and seals. Proper design of system is a must, you do not want to weld after these are in place, due to the possibility of damage. Hope this helps.

Also talk to a pneumatic conveying consultant to check the material velocity. You could have too much line pressure or insufficient pipe diameter. Elbow wear may be just a symptom and not the root problem.

I believe your primary problem is too small diameter pipes and, likely, too high transport pressure with too high material velocity.

What you WANT is to move the materials down to the receiver. Do this with large pipes about 90% full moving slowly using a low-pressure volume blower to keep the charge fluidized and moving relatively slowly.

The system will have a "film" of air at the perimeter of the charge and the charge will be very low density. The low velocity and the air film near the inner surface of the pipe will make the abrasion virtually non-existent.

AND the low pressure blower will use less electricity to keep you from spending too much on "trash".

This is pure Bulk Solids Handling problem.

You better approach an engineering firm specializing in that.

From my experience, depends on the temperature, chutes are usually coated by HDPE. Also note that chutes are usually of rectangular cross section (better for the bulk solids flow and for maintenance purposes (as coat replacement)).

Your high wear rate suggests that you are using lean phase positive pressure conveying. I will answer on that basis.

1 As already stated, it looks as though you are conveying at too high a speed. There is a fine balance, reduce the speed too much and you get blockages, have it too high and you get excessive wear. Get the original design calculations checked by an independent expert. You may be able to claim replacement costs against the original supplier. NB. On high volume air systems, changing the ratio of the belt drive pulleys between the blower and motor is a lot cheaper than adding a VSD to control the blower output.

2 Stainless steel is a soft material, next time you have the problem change to mild steel pipe. (and save money)

3 The problem occurs at or just after a bend. This is quite common because the product effectively shot blasts the outer curve of the pipe as it rounds the bend. This does not happen on straight sections. Install "wear bends" at all changes of direction Google "Pellbow" for a good video of the problem and solution. There are a few manufacturers and these bends are expensive, so get competitive quotes.

4 If the system is over a long distance, consider leaving the pipe diameter at 6" where you feed in the material and stepping it up to 7" and then possibly 8" further down stream. As the pressure drops along the line, the material speed increases to obey the conservation of energy equations. Stepping up the pipe diameter will keep the material speed more constant. You should aim for a speed of 15-18meters/second with fly ash.

5 This is a field for experts. The calculations are complex and every material conveyed produces different results. Before installing any new system you should get flow and wear rates confirmed on a test set-up, as you have found to your cost. There are still many practitioners who regard pneumatic conveying as a black art rather than a science, so get any potential supplier to show you calculations and explain in detail how they arrived at their proposal for supply.

Everything stated here is totally on track.

My earlier response was focused on a redesign of your system (since you have to change much of the material anyway) and I did not get as deeply into all the issues.

I won an international energy award for a pneumatic conveying system that I designed that used the "engineered" approach, and a little creativity- a combination of "lean phase" (lots of air vs. product) noted here and "dense phase" (much more product than air) in my post- rather than the much more common "black art" method of "what product = X fpm transport velocity" with no understanding of potential system degradation.

We provide abrasive-resistant valves and corrosive-resistant valves (ceramic lined ball valve) for ash and coal conveying system,the valve has been very sucessful used in Pneumatic Conveying system to save the down time for the system.Hope this will help to you if there is any demand.

Dear sir,

I am the "AMIE"student,

As i am doing the project related to the pnumatic conveying system.

I need help from your end.

As the air consuption and pipe size calculations releated to the pnumatic conveying system.

I will help if I can but we have a policy on CR4 of not doing a students work for them. We feel that is counter productive. There are enough badly trained or lazy engineers around without us adding to the total.

First there are several ways of conveying material pneumatically. You can transfer by positive pressure or vacuum and you can have dense phase where the material is carried over intermittently in dense slugs, or lean phase where the material is continuously fed into the air stream at a controlled rate. Different material, material volumes and run lengths dictate which is the best option for you so you need to know; what the material is, where it is stored (One of the hard bits is getting the material to flow into the pipe/air stream), how and where it will be used (The next hard bit is getting the material out of the pipe/air stream), the rate it will be transferred at, the total length it has to be carried (Work out a route with the minimum number of bends. Only use horizontal and vertical legs, slopes are a no no. No two bends should be closer than thirty pipe diameters apart as bends slow down the product and it has to have chance to pick up speed again before it comes to the next bend. Remember that if you have a vertical leg the elbow at the bottom and the elbow at the top can be set to different horizontal angles so you can change horizontal direction without adding an extra bend. Is your product abrasive? Can you use long radius bends or do you need special wear bends? Finally pipe work does not hang in mid air, it has to be supported from something rigid, so you route has to take this into account.)

Now you have the basics you have to do some research. Find out which type of transfer system is used for different products and different transfer rates and why. Don't just look at the transfer itself think laterally. If your product is toxic would you prefer a positive pressure system or a vacuum system and why? Once you know the type of system you are building you need to know the ratio between air and product. There are tables for this, look up the numbers. You need to know the optimum speed. Too fast and you wear out the pipes, too slow and the product drops out of the air stream. Tables again. Once you know the speed and the amount of air you can calculate the pipe size, and the size of compressor/vacuum pump you need. You need to get product into the air stream, what equipment will you use? At the far end you need to segregate the conveying medium from the product, how?

You have to tackle this project methodically. Find out what data you need and where to get it. Gather the data. Do the calculations. Write a schedule of equipment and materials required. I would be surprised if costing up your schedule and working out the labour needed to do the job is in the scope of your project but that would be the next step if you were doing this for real. Write up a proposal of how your system will operate and any assumptions that you have made. Include all your sizing calculations in an appendix.

Get a copy of "Fan Engineering" by Buffalo Forge Company.

It has a section specifically on Pneumatic Conveying and- if you read it like a student wanting to learn everything about the topic- you will learn EVERYTHING that you need to know, including when to use whichever phase AND how to select the proper volume and velocity to meet YOUR needs.

Keep an OPEN MIND as you read it- you MAY come up with some really interesting solutions. The information I learned was the basis of my International First Place- Industrial Division Energy Award.

Suggesting to weld an "elbow" on the worn pipe section !! - This will contain some fine coal in the worn region , and in this way-will reduce the friction wearing !!

Just deal with it...

I knew people smarter than me would add to my suggestion, you have some excellent posts to look at here.

See the Forum Thread of Jan. 8th, 2012 about hammertek elbows. This should provide the protection at the vertical drop to prevent the wear at that point. And like a previous post get rid of the stainless, much to soft a material. A Ni-resist iron would be far superior. Or like the post, get a steel elbow and weld a channel on the outside so eventually when it wears through the elbow it will the form a pocket which will fill with the ash and stay in that pocket creating an ash on ash contact thus acting as a buffer for the steel elbow.

We did this in pneumatic sand transport elbows and it worked fine.

Use the Forum search for "hammertek"

Devcon and Locktite make wear-resistant epoxies designed to reduce the problem you are having.

While the correct answer might be to reengineer the delivery system, the epoxy might be an affordable way to extend the time between replacement pipes.

For the pipe lined I suggest you to use ceramic lined pipe,the ceramics are made of Al2O3 which the hardness is several times higher than SS-304.

Do you also face the problem of the valve use to this application?Ash and coal conveying is really abrasion to wear out the valve.You can consider the ceramic lined valves which can last service life many times longer than normal valves,to save the down time for your system.