Custom boilers meet capacity, emissions challenges (TIA)
Many refinery complexes in Texas are ageing. It is not uncommon to find boilers that are 50 or more years old. As a result, these facilities can be liable to costly unplanned outages, as well as higher fuel costs due to inefficiency. In addition, ever stricter environmental regulations can require upgrades to bring refineries within acceptable limits.
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Take the case of the Air Liquide Bayport Complex. A variety of factors drove the decision to initiate the upgrade of its cogeneration units to raise efficiency, production capacity and lifespan. This included replacement of boilers from the 1960s that suffered from poor reliability and efficiency. Rentech Boiler Systems supplied three new auxiliary boilers to support the existing air separation units at the complex.
Air Liquide Large Industries US supplies large quantities of industrial and speciality gases in an array of volumes and purities, along with related technologies and services to customers in the metals, chemicals, refining, energy, pharmaceuticals, food and beverage, manufacturing, materials handling, laboratories and research, aeronautics and space industries. It offers a range of gas supply modes, including cylinder and bulk delivery, pipeline distribution, and onsite production. These companies have substantial gas consumption needs and demand a reliable and continuous supply of oxygen, nitrogen, hydrogen and syngas. Delivery is made either through a dedicated plant or via the Air Liquide pipeline network.
Air Liquide is present in 80 countries with approximately 65 000 employees and serves more than 3.5 million customers and patients. It employs more than 5000 people in the US in over 200 locations. About 100 of them are employed at its Bayport complex situated near Houston, Texas. This facility covers 88 acres of land and supplies oxygen, nitrogen, argon, hydrogen, electricity, steam, and industrial and demineralised water. It is central to the company’s extensive Gulf Coast Pipeline System, which encompasses approximately 2000 miles of pipeline along the Gulf Coast of Texas and Louisiana. The facility also includes a major bulk distribution depot.
The Bayport Complex, near Houston, Texas, is unique compared to all other Air Liquide facilities. It is the only facility to have on-site air separation units, cogeneration units, boilers, industrial water treatment, and a steam methane reformer. It has long served as the heart of the company’s Gulf Coast operations, supplying product to customers via pipeline, truck and rail.
However, the facility needed a major upgrade to increase capacity while meeting stringent emissions requirements. Accordingly, Air Liquide invested around $230 million to upgrade its cogeneration plant. The investment is supported by a long-term contract renewal within the Bayport Industrial District and will also help Air Liquide meet the growing needs of other customers throughout the Texas regional basin.
This included energy efficient upgrades made to four cogeneration units to increase production capacity and extend the life of the units by more than 20 years. The facility now has the capacity to produce 300 MW of electricity and more than 1300 t/h of steam.
The project included replacement of three auxiliary boilers and steam plant infrastructure upgrades that support the existing air separation units. The previous boilers were installed in the 1960s. They suffered from poor reliability and efficiency.
Rentech Boiler Systems supplied three 400000 lb/h direct fired boilers. These factory assembled natural circulation water tube boilers include drainable convective superheaters that operate at lower gas side temperatures to extend superheater life. Two stage convective superheaters greatly improve performance over turndown.
Rentech custom engineered these boilers for the Bayport facility. In addition to conservative steam drum sizing, the company employs chevron vane separation technology to minimise moisture carryover. The boiler design also accommodates high cycling operation, and 100% membrane wall fabrication provides a fully water cooled furnace with zero gas bypass and lower emissions. As a result, there is no need for refractory walls or refractory seals. This design approach reduces operating costs as it requires less maintenance to repair or replace damaged refractory, while enabling faster start-up and cooldown.
The maintenance manager at Air Liquide notes the boilers are installed and operating well. Reliability is much higher, and emissions have been considerably reduced.
This short case study originally appeared in PTQ's Technology In Action feature - Q4 2019 issue.
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