Article 6: Nitech™ Nitrogen Rejection with integrated helium extraction

Author: Greg Hall, Vice President of Sales/Planning, BCCK Engineering
Publication: Hydrocarbon Engineering
Date: January 2011

Formed through the radioactive decay of heavy metals uranium and thorium, the vast majority of the earth’s supply of helium permeates through the earth’s surface and, being lighter than air, eventually dissipates into outer space. As it is not currently feasible or economic to process the helium existing in the atmosphere, the majority of the world’s helium supply is processed from non-porous cavities which also contain high nitrogen natural gas. Should conditions merit, for gas processors fortunate enough to find helium reserves comingled in their low-BTU natural gas plays, the helium stream can be of significant monetary value. Since nitrogen rejection and helium recovery go hand in hand, the helium recovery aspect can greatly enhance the project economics for low-BTU gas processing and BCCK has proven the integration of helium recovery with the Nitech™ NRU process.

Uses of Helium

Because of helium’s unique properties including low boiling point, low density, low solubility, high thermal conductivity and inertness, it is the preferred, if not only, element available for use in a variety of applications. The largest user of helium in the United States involves cooling the superconducting magnets used in medical MRI scanners. Other major uses include shield gas for welding, leak detection, production of silicon wafers for fiber optics, cooling nuclear reactors, lifting and the production of rocket fuel and pressurization of fuel cells for the space program. The limited supply of helium in Europe has necessitated the use of a different compound for use in MRI scanners worldwide, but helium is still the preferred medium for MRI’s used in the United States and will continue to be used as long as helium is readily available domestically. According to the NAS Helium Study, new applications depending on the use of helium include magnetic levitation for transportation applications, superconducting magnetic energy storage, energy conversion systems, cryogenic wind tunnels and superconducting electronics.

Worldwide Helium Reserves

Although helium is the second most common element in the universe, within a few decades, the known recoverable helium reserves may be depleted; a sobering statistic for anyone needing an MRI as MRI machines currently account for more than one quarter of the helium used in the United States. The primary locations for known recoverable reserves are the United States, primarily in the Texas panhandle, Oklahoma panhandle and Kansas where helium concentrations can reach up to 7% as seen in a field in the San Juan basin of New Mexico. The U.S. Government controlled Federal Helium Reserve is located near Amarillo, Texas in the only known rock formation on the planet where helium can be stored – the Bush Dome in the Cliffside Gas Field. The Helium Acts Amendments of 1960 established the helium conservation program which led to the installation of a helium pipeline from Bushton, Kansas connecting several private helium recovery facilities to the storage area at the Bush Dome.

For many years, the United States produced greater than 90% of the commercially available helium; however, in the 1990’s a new plant in Algeria was brought online with the capability of covering the existing helium demand in Europe. Helium reserves in Canada, Russia, Poland and Eastern Europe have also been proven. However, as demand for helium continues to rise, economists, scientist and gas processors alike are painfully aware of the finite supply of helium available for recovery.

Helium Pricing Structure

In the 1920’s the United States government, recognizing the commercial and strategic value of a finite resource, took control of the domestic helium market. By 1960’s, the government had committed to purchase any and all helium reserves recovered from Texas to Kansas. With a willing and committed buyer in play, private companies were willing to invest in the development of helium extraction facilities along the proposed helium pipeline. Nevertheless, the helium reserves stored at the Federal Helium Reserve soon outpaced market demand ad by the late 1970’s the U.S. government cancelled its purchasing policies. Today the federal reserve of helium is priced in excess of the private market price, thereby allowing the BLM to set a relative cap on the price of helium. However, as mandated in the Helium Privatization Act of 1996, the BLM is currently allowing for the depletion of the federal reserves held in the Bush Dome Reservoir in order to meet some of the short term demand for helium. Once the bulk of the federally owned helium has been sold, the private price for helium should begin to escalate. In August of 2010, the BLM announced that upon recommendation of the recently released National Academy of Science’s report “Selling the Nation’s Helium Reserve” the BLM will sell crude grade helium at $75/MCF as compared with previous price of $64.75/MCF. Natural gas producers are becoming increasingly aware of the economic rewards of helium extraction in conjunction with natural gas processing. As future applications for helium increase and existing helium reserves are depleted, the appetite for helium extraction is likely to grow, ostensibly resulting in a larger percentage of helium being extracted from available natural gas streams which were once considered too costly to process or even in the deliberate exploration for new helium sources worldwide.

Nitrogen Rejection and Integrated Helium Extraction

BCCK has successfully designed, constructed and installed eighteen nitrogen rejection facilities using its patented NitechTM technology. Three of the eighteen facilities were designed to incorporate a helium recovery system, integrated with the Nitech™ process, to provide a crude grade helium stream. The crude grade helium product stream can then be processed to a purity of 99.99% with additional equipment outside BCCK’s Nitech™ unit. The low BTU gas is routed through the NitechTM nitrogen rejection unit (NRU) where the nitrogen and helium are cryogenically separated from the hydrocarbon constituent of the inlet gas stream in order to process an on-spec natural gas product. The helium rich nitrogen stream exits the Nitech™ NRU at high pressure and at dew point making the addition of a helium recovery system straightforward. Helium removal is accomplished through cryogenic distillation utilizing refrigeration provided by liquid nitrogen produced within the BCCK helium recovery unit (HeRU). The liquid nitrogen stream is used purify the helium product to between 75 and 95% helium quality, with the balance being primarily nitrogen. The additional equipment required to be integrated with the Nitech™ NRU for the separation of the nitrogen and the helium is minimal and includes a plate fin heat exchanger, a distillation column and a helium product compressor. No cryogenic rotating equipment is required. Typical recoveries of inlet helium are in excess of 99% and the product can then be compressed and transported via pipeline or truck to downstream purification/liquefaction facilities.

Case Study – Kansas Facility (First Nitech™ NRU Integrated with Helium Recovery)

BCCK built and successfully proved its first Nitech™ unit with integrated helium recovery near Offerle, Kansas, in 2001. The Kansas facility processed an inlet gas stream containing 20% of nitrogen and less than 1% helium by volume. Once processed, the resulting crude grade helium was at a quality in excess of 90% with over 98% of the inlet helium recovered as salable crude grade helium. The facility included helium compression that compressed the product into tube trailers on site. These trailers were then transported to a nearby purifier/liquefier facility. The downstream purifier did not require the crude helium to be as high in quality, but by producing as pure of a product as possible the owner was able to save costs on transportation. This was due to being able to deliver larger volumes of helium with each truckload. The Kansas facility, designed and installed by BCCK Engineering, included equipment for carbon dioxide removal, dehydration (mole sieve), nitrogen rejection including a NitechTM NRU with integrated NGL extraction and as previously mentioned integrated HeRU system and associated compression.

Case Study – Western Wyoming (200 MMSCFD)

Although helium reserves in Wyoming have been well documented, typically the natural gas in the area is of such low quality, due to ultra high levels of carbon dioxide, hydrogen sulfide and nitrogen, that producers have decided that it is not economical to process the natural gas and in parallel, recover the helium. This is not only due to the low quality of the inlet gas stream, but also due to environmental concerns and associated costs with the disposition of the high quantities of both carbon dioxide and hydrogen sulfide in the inlet gas stream. However, as the helium reserves at Cliffside and the amount of helium processed in the Hugoton Basin decline, second market sources for helium will become increasingly valuable. In addition, availability of newer and more up to date technologies for both carbon dioxide removal and for nitrogen rejection/helium recovery have made these previously underutilized reserves more economically viable while meeting the increasing environmental demands. BCCK has designed and is currently installing the processing facility, including a NitechTM NRU with integrated helium recovery, in Western Wyoming. In addition to the integrated NRU/HeRU, the facility is designed for both carbon dioxide and hydrogen sulfide removal and sequestration. Although the inlet helium content is less than 0.5% by volume, the helium product stream will be a significant revenue generating product stream for the facility. The crude grade helium product stream will be piped to a downstream purification/liquefaction facility. The Wyoming facility is designed to recover in excess of 99% of the available inlet helium as well as a more than 99% of the inlet methane to the facility. The crude helium product for this facility is only required to be 50% helium quality with the balance nitrogen. The Nitech™ system and associated HeRU can deliver a much higher quality helium product, but by providing a higher nitrogen percentage to the feed of the purifier/liquefier the costs of that system were reduced by allowing it to generate its own refrigeration utilizing the excess nitrogen. Due to the flexibility of the Nitech™ system, this modification will only require operational set point changes and did not affect the design of the facility. Since the crude product is being piped the purifier/liquefier, shipping concerns due to weight and the volume of the nitrogen in the crude helium were basically eliminated. This facility is set to come on-line in late 2011.

Conclusions

As the worldwide demand for helium increases, producers will continue to search for additional helium reserves, which will mean that there will be an increased demand for nitrogen rejection technology. Advances in technology, such as BCCK’s Nitech™ process, have made low BTU reserves more attractive and the addition of potential helium recovery will enhance project economics even more. Should helium be present in the low BTU stream, with the minimal equipment required by the NitechTM process, producers will be able to economically liberate stranded helium reserves in conjunction with upgrading their low BTU gas.

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