FLOAT GLASS PRODUCTION Nel Hydrogen 124 Glass-Technology International 5/2020 nel hydrogen art GTI5.indd 124 12/10/20 12:07 Nel’s Alkaline Water Electrolysers (Hydrogen Generators) have been in use for decades at float glass manufacturing facilities Nel is a global, dedicated hydrogen company, delivering optimal solutions to produce, store and distribute hydrogen from renewable energy. Since its foundation in 1927, Nel has a history of development and continual improvement of hydrogen plants covering the entire value chain, from hydrogen production technologies to the manufacturing of hydrogen fuelling stations, providing all fuel cell electric vehicles with the same fast fuelling and long range as conventional vehicles today. Raymond Schmid - VP Sales and Marketing EMEA-Oceania ON-SITE TIN Nel Hydrogen irst developed by Sir tomotive windshields and Alistair Pilkington in more. If you see a clear or BATH F 1952, the float glass tinted flat piece of glass, it process creates a special- was most likely manufac- ised type of flat glass with tured using the float glass ATMOSPHERE an extremely smooth, uni- process. form structure and supe- rior optical qualities. Over THE PRODUCTION the past 60 years, this OF FLOAT GLASS GENERATION method has not lost its rel- Float glass is produced on evance. Today float glass a continuous production is everywhere. It is used line. First, raw materials IMPROVES to construct windows and such as sand, dolomite, doors, the glass ‘skins’ of limestone, carbonate and modern skyscrapers, ta- sodium sulfate, as well bles, shelving and display as scrap glass are heated FLOAT GLASS cases, solar panels, plasma, to extreme temperatures PRODUCTION LCD and LED screens, au- (1,500°C/2,800°F) to form Glass-Technology International 5/2020 125 nel hydrogen art GTI5.indd 125 12/10/20 12:07 FLOAT GLASS PRODUCTION As stand-alone units or working together in a network for greater output, Nel PEM Water Electrolysers offer the safest, most advanced technology for producing high purity hydrogen for float glass atmospheres molten glass. This glassy template for the glass to the most important tasks at to stop this oxidation from liquid then moves into the distribute over and then this stage is to prevent the occurring and to avoid tin bath chamber, which harden into high-quality interaction of oxygen with a negative impact on the has a controlled atmos- flat glass. the tin. glass, a protective atmos- phere, where it is poured Tin is a metal that does The oxidation of tin in- phere is used in the tin onto the surface of molten not react with glass, but troduces flaws in the tin’s bath chamber. This atmos- tin. As the molten glass is the forming basis for a structure, which in turn phere usually consists of floats on top of this tin flat surface of glass with- will create flaws in the sur- 90 per cent nitrogen (N2) bath, the tin acts as a level out optical defects. One of face of the glass. In order and 10 per cent hydrogen 126 Glass-Technology International 5/2020 nel hydrogen art GTI5.indd 126 12/10/20 12:07 (H2). While the nitrogen tion purposes have used a high risk of explosion. and creates carbon dioxide remains non-reactive in the compressed gas or liquid Given the high volume of (CO2) emissions, a very process, the hydrogen will forms of nitrogen and hy- nitrogen required in the damaging greenhouse gas. react with any oxygen pre- drogen, which are supplied float glass process, the lo- Depending on the method sent, preventing any oxida- by pipeline from a nearby gistics of transporting the used, for every ton of H2 tion of the tin. producer, or by trucks in nitrogen to the glass plant produced, 11 to 19 tons of tanks or tube trailers. How- can also present a problem. CO2 is released. DETERMINING ever, this is not without its Any disruption to the sup- The main driver for CG WHICH TECHNOLOGY problems. ply chain, whether from a and SMR applications is IS BEST – USING strike, natural disaster or the low specific cost of THE RIGHT GAS Nitrogen global pandemic can cut hydrogen produced. How- In order to determine Nitrogen is typically pro- off the flow of nitrogen to ever, the disadvantages are which technology is the duced with air separation the plant causing a shut- the high cost of equipment, best to produce protective units using pressure swing down of production. To costly and lengthy mainte- atmospheres, there are sev- absorption technologies. help keep glass production nance, and the presence of eral factors to considered: This method provides the operating at peak efficiency impurities in the hydrogen, • High purity require- highest purity of nitrogen and safety, plant managers which requires additional ments for process gases available, and can be cooled should consider installing purification equipment. • Large volume of gas and compressed into liq- air separation units on-site Add to that the changing demand (average: 800 uid form and stored cryo- to replace, or at least sup- attitudes and legislation Nm3/h nitrogen and 90 genic containers. However, plement delivered nitrogen. around the world on green- Nm3/h hydrogen) whether as a compressed house gas emissions, de- • Sourcing gas supply gas or liquid, nitrogen is a Hydrogen carbonization of industries • Environmental impact dangerous element to store. Most hydrogen is produced and the expense of carbon of generating the gasses If it escapes into an en- via coal gasification (CG) capture equipment now be- Traditionally, industries closed space, there is a high or steam methane reform- ing required, CG and SMR that require high volumes risk of asphyxiation, or if ing (SMR), which uses are starting to fall out of of these gasses for produc- pressure builds up there is fossil fuels as the feed stock favour. In addition, liquid Nel Water Electrolysers (Hydrogen Generators) for float glass manufacturing Glass-Technology International 5/2020 127 nel hydrogen art GTI5.indd 127 12/10/20 12:07 FLOAT GLASS PRODUCTION hydrogen is highly explo- legislation. By producing and the differential pres- constantly monitor the op- sive which means it must the hydrogen on-site as sure between the hydro- eration process adhering be handled very care- needed, the plants can also gen and oxygen streams to several dozens of safety fully, and requires a large eliminate the safety and ensures that there is no parameters. storage area and special storage problems of deliv- mixing of the gasses. This As float glass facility man- permitting. ered hydrogen. mechanism of the Proton agers contemplate changes Hydrogen production PEM system has brought or additions to their tin through traditional alka- WATER ELECTROLYSIS water electrolysis to a new bath atmosphere supplies, line water electrolysis is a – THE OPTIMAL level of safety. The high it should be noted that well-known technology to CHOICE purity of hydrogen is due to each project requires a the glass market. In this Given the importance of using pure DI water as the detailed technical and eco- process, the electrolyser hydrogen purity for the only raw material. Hydro- nomic analysis, taking into uses a liquid alkaline elec- float glass process, all the gen purification consists account specific plant re- trolyte (NaOH or KOH) features of CG and SMR of drying the hydrogen quirements. Nel Hydrogen to facilitate the electrolysis. operations, and the same through two internally in- produces hydrogen gen- While installation of an al- logistic problems for de- stalled pressure swing ab- erators, both alkaline and kaline system may require livered hydrogen as for sorption tubes. There is Proton PEM technologies, RTN and other permits as delivered nitrogen, the pro- no need to have additional and can match the needs well as additional inspec- cess of water electrolysis is purification and treatment of any float glass opera- tions and special insurance the optimal choice for the equipment. The standard tion. Nel provides turnkey due to the caustic nature float glass process. Today purity of hydrogen is guar- solutions… the implemen- of the alkali, the system is the safest, most advanced anteed at a level of not less tation of all stages includ- extremely reliable and ef- technology to produce the than 99.9995 per cent with ing production, delivery, ficient. Many float glass purest hydrogen is through a dew point of 72°C. commissioning, warranty plants have been using this Proton Exchange Mem- With the absence of a and post-warranty service technology for decades to brane (PEM) water elec- liquid alkaline tank and throughout the life of the produce the hydrogen they trolysis. This process uses mechanical high-pressure equipment. require for their tin bath a caustic free solid polymer compression on the hydro- atmospheres. Because the electrolyte as the catalyst to gen line, PEM systems are hydrogen produced by wa- crack the water molecule more compact than their ter electrolysis is generated (H2O) into hydrogen (H2) Alkaline counterparts. A by cracking water mol- and oxygen (O2). more important benefit ® ecules (H2O) into hydro- In a Nel Proton PEM that comes with the ab- gen (H2) and oxygen(O2) electrolyser, deionized wa- sence of alkali in the PEM using only electricity and ter and electricity are fed systems in the lack of need an electrolyte, no green- into the cell stack. Here, for ‘hazardous production Nel Hydrogenyg house gasses are produced. water splits at the anode facility’ signs, RTN and The only by-product is into electrons, protons other special permitting, oxygen. When hooked up and gaseous oxygen (O2) additional inspections and to a source of renewable at a pressure of 1.5 barg. special insurance. energy for the electricity, Protons then pass through Nel electrolysers oper- true green (zero carbon) the proton exchange mem- ate automatically and do hydrogen is produced.