30MPa reciprocating compressor for pure hydrogen

Reply to 1# zenme1314lsw: Haha, I’ve never played with anything this high-pressure; even pure oxygen at 15 MPa scares me. Personal thoughts: 1. Carbon buildup in the high-pressure section valves – where does this carbon come from? Does the medium contain organic components? How is the H gas source obtained? 2. Could you tell me about the material of the piston rings? I’m sorry, I can’t help you.

Reply to 1# zenme1314lsw: The main reason is likely that the temperature of the medium entering your machine is too high; hydrogen carrying light hydrocarbons forms carbon deposits when exposed to high temperatures and pressures. Controlling the medium temperature at the machine inlet is key.

The piston rings of high-pressure reciprocating engines are all oil-lubricated. When the exhaust temperature is high, the exhaust gas carries the oil and gas from the cylinder into the exhaust valve; the high temperature causes the lubricating oil to degrade, leading to carbon deposition. Increase the cooling water flow in the intercooler to lower the intake air temperature

Reply to 2# zouq.blsh: The compressor we encountered was one using pure hydrogen at 30 MPa. Hydrogen is very clean, purified to 99.6%. The source of hydrogen is the chlor-alkali industry, which electrolyzes saltwater. The hydrogen compressor features 7-stage compression. The first one in the country. The inlet pressure is 0.056 MPa. The outlet temperature at all levels is below 120 degrees. The inlet temperature is 35 degrees. The low-pressure areas ahead, from level 1 to 4, are all clear. Carbon buildup can easily occur in high-pressure stage 6 and stage 7 valves. It also doesn’t look like it’s carbonized from lubricant. Helbig is used for the packing and piston rings.

Is the poster sure that the foreign substance on the valve is carbon buildup? If so, the hydrogen produced through electrolysis should be free of carbon; therefore, it’s necessary to find out where the carbon comes from. As the poster mentioned, if the hydrogen content is over 99%, then the drying system used must be very effective. What type of desiccant is being used? If it’s a carbon-free substance (such as concentrated sulfuric acid), then the carbon must come from the lubricating oil. It is recommended that the poster conduct infrared absorption spectroscopy and total acid value analysis on the lubricating oil to determine its degree of degradation.

Reply to 6# ypliang: An analysis of the pH values of the oil-water mixtures at various levels was conducted, and only the oil-water mixture at level 1 had a pH value of 11. Levels 5, 6, and 7 show around 6. The lubricant I was using before is almost past its expiration date. But a new lubricant has now been installed. Water removal from hydrogen is carried out using a low-temperature method, by cooling the hydrogen to 5 degrees. The hydrogen concentration is 99.6% in all cases. I have a question for everyone: Hydrogen is produced by electrolyzing saltwater, and could chloride ions present in it cause corrosion to pipelines, buffers, and coolers? The cooler tubes show signs of pitting. Under high pressure, corrosion of the pipelines intensifies. Carbon buildup in the valve could be rust. I’d like to ask everyone.

Our previous method for purging separators and buffer tanks was to remove the root valve, start the system and pressurize it for purging, while also using a hammer to strike them.

This post was last edited by zpg on 2010-11-22 at 13:23. 99.6% hydrogen is not considered pure; haha, the key is to know what makes up those remaining 0.4%. It’s normal for hydrogen used in the chlor-alkali industry to contain chlorine. It is recommended that the poster conduct a comprehensive analysis of the hydrogen’s composition, making sure to check for any impurities present in very small amounts, even at the PPM level. I’ve encountered hydrogen with four 9s in purity, at 30 MPa, and there was no issue with carbon deposition as mentioned by the poster; the total amount of other impurities was only around 100 PPM – that’s what truly counts as pure hydrogen. Overall, it seems like the problem lies with the lubricant. In hydrogen used in the chlor-alkali industry, the only source of carbon is CO2. The friend in post 6 is very knowledgeable; analyzing the carbon deposition should help identify the cause easily.

First, conduct an analysis to determine exactly what it is, and then decide on appropriate countermeasures based on the source. It is recommended to install a filtering separator to see how effective it is at keeping impurities out of the compressor.

This post was last edited by andyzh2009 on 2010-11-22 at 16:13. The compressor piston ring and support ring of the original poster aren’t worn out at all; is the carbon buildup you mentioned debris resulting from the wear of those two rings? Regarding the addition of a filter-type separator mentioned upstairs, what mesh size filter do you need?...