I manage a helium recovery system. Labs use liquid helium for their experiments and I recover that helium as gas and liquidfy it.
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I manage and maintain a helium recovery system for a lab. We have a closed cycle helium recovery system. I give labs liquid helium and they use it and it comes back to the system as gas.
We use liquid helium because of its cold temperatures. Regularly at 4.2k. We recycle helium because its fairly expensive to get and its not a very renewable resource. a big part of my job is to babysit the machines and make sure they are working properly.
We recently bought some gas meters by EKM metering. They have some pretty fancy IOT style metering options for sale. We bought the EKM push and omnimeter pulse v.4
Helium gas meter installed to measure the gas flow. We can see which lab uses helium and it can log the data. Its good to know if a lab uses helium and make sure what is being sent from the lab also gets returned back to our system.
please excuse my messy wiring. I used Circular power connectors From TE connectivity for the pulse wiring and the pressure guage sensor wires.
Purity manifold. Top is moisture count in helium. Measured in Parts per million. Below is percent oxygen in the helium space. That reading should usually read 0.00. We had a really bad leak in the system.
We had to relocate a few of the machines to accommodate the big liquidfier so we set up a new stainless steel line and some water lines. Tested with helium at the rated pressures and then i left it for a week and checked on the pressures once in a while.
First the helium is sent from the labs through piping throughout our building. The building was designed to have helium recovery in mind. Most of it is hard soldered copper 2" throughout. Older parts of the building use regular black iron pipe.
The gas is sent to our purifier. How it works is it basically freezes the gas. Most gasses liquidfy well above liquid helium temperatures. So we have a quantum design branded purifier. It uses a gifford mcmahon cryocooler to freeze the gas to 10-30K and everything that comes out of the purifier is fairly pure helium. 99.999 percent pure. Our inlet purity for helium needs to be at least 99.9 percent pure or better. If its contaminated with air or oxygen. The purifier warms up to 130K to exhaust the other gasses and then cools back down to temps between 10-30K.
We had a cryomech purifier but it failed a few months back. The manufacture suggested we try a few things and replace a few parts. But due to how complex the boards were, we were unable to fix the issue. We are planning to send the unit back to the factory for refurbishment.
The liquid helium level is measured once an hour with a liquid level indicator. It is a superconducting strip inside the dewar space. As it liquidfys helium. the strip becomes superconducting and the resistance of the wire changes. That is calculated and we get a measurement in inches. We have a corresponding chart where we determine the amount inside the dewar.
Once there is enough liquid inside the liquidfier. We can do a transfer to a portable Dewar that gets sent to the labs. We insert the transfer siphon into the dewar and we also connect the gas exhaust from the dewar into the recovery system. The transfer process is quite inefficient. A regular transfer will lose around 30 percent of the liquid each transfer. All of that turns into gas and we capture it. The gas outlet is cold enough that it liquidfys the air around it...
The labs uses the helium for their microscopes and other experiments and then the cycle repeats.
This is our bigger liquidfier. I installed this over a few months. We had to run braided stainless steel helium lines to the pulse tubes to the external compressors. The units are from CryoMech. It has a 500L dewar and it can liquidfy 60L a day.
More photos of the compressors. They use pulse tube refrigerators. The compressors are similar to a hvac style compressor. It has a Hitachi Scroll compressor unit inside modified for helium use. Each stainless steel line is pressurized to 200 PSI and it uses helium as a refrigerant.
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This took place between 2020-2021 It took a few months to set up and fully finish. It took a while to run the electrical, set up plumbing for water and run the helium gas lines.
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