NPN Corrosive Coating

Teflon?

you will find it is more economical to make the filter out of the required stainless steel rather than try to get a holiday free coating on mild steel. The filter mesh cost is peanuts compared to the headaches you are asking to get.

You are right on target with this reply.

To be honest, I work for a coating manufacturer that produces a range of chemically resistant products, but reading your request I find that there are conflicting details.

I do believe that Mr. Bowers is on point when he mentions that you will have a hard time avoiding other problems, if you are not using the prescribed solution. I think that most chemically resistant coatings that go on thin and are not very expensive end up being solvent borne products. This increases the risk of premature failure due to entrapment of the same solvent used as a vehicle.

If you do not wish to use SS, we would need to know just what the gases are (not familiar with the biomass gasification process, but I figure the gases are different around the world with different biomass fuels), and then find the coating you seek for this service (temperature can also be a limiting factor).

You then compare your projection of life in service for this solution and the cost of it to the cost of your conventional SS, and we are talking business.

Here's a thought: our people believe we should stick to the original design when possible, and only use similar materials when needed. Therefore my best recommendation would be to consider coating your SS originals (new if necessary) and extending their life.

Is there a functional reason why you do not want to use the SS (other than cost, lead time, etc.)?

I thank you for the chance to learn about the biomass process in advance (if you can provide the details of the corrosive components in the gas, and/or maybe guide me to a good resource online to get it myself).

Mr.Robert,

Thanx for your response. The Average composition of a producer gas is as under. CO¦ 20±2%_, CH₄¦2±1%, H₂¦20±2%, CO₂¦12±2% and rest N₂. After extracting the gas from the biomass, the gas is made to pass through a cleaning system which includes the Filter. The material of construction of all the components of the gasifier is SS304. The filter is bulky as the filtering process requires high surface area for the filteration process. The filteration is through the fabric material. The typical weight of the filter is in the range of 300 to 500 Kg of SS304 which makes it expensive. In terms of surface area for coating, it will be in the range of 2.5 to 3 square meter. The basic purpose of the SS304 is to avoid corrosion.

Hence in order to make our system competetive, we are looking for a corrosion resistant coating on the Mild steel plate.

If you have any further query, please feel to express.

In anticipation of your reply,

cdrgar

I have no experience in the biomass industry. But the thought of plastics comes to mind. Polyvinyl Chloride (PVC) and Polypropylene (PPE) are both commercially available in perforated sheets. Both are easy to work with and weld, have good corrosion resistance, and cheaper and lighter than SS. Try www.usplastic.com Let us know.

The composition you described for the gas solution, does not seem to reflect corrosive individual parts. With CO, CH₄, H₂, CO₂, and N₂ a number of different things can be causing your corrosion. For example you can be forming carbonic acid: H₂CO₃.

Is the corrosion due to moisture alone?

What is the operating temperature? What are the maximum peaks?

Feel free to forward details directly to my address: rcameron@belzona.com

I know your initial post was sometime ago, please excuse my delay. In case I can be of service, this is what I focus on professionally and I have therefore been trained as a NACE CIP Level 2 Inspector. I am certain you can find a number of alternatives in the coatings industry, but without certain details, we might not be addressing the root cause of corrosion.

You are welcome to reach me directly at your convenience, and I will be sure to respond in a prompt fashion (at the moment I've been traveling and this site is not Blackberry friendly).

Thanks again for your description of the flue gases in the Biomass process.

Kind regards!