Downstream focus: Lummus Technology

Lummus Technology, a CB&I company, is a leading supplier of licensed, proprietary technologies to the petrochemical, refining, gas separation, and polymers industries with over 75 technologies in our portfolio. All of these technologies are available for open licensing. Specifically for petrochemicals producers, Lummus Technology has over 30 processes available for license.

What differs your technology from other competitors and what are the latest innovations in your technologies?

Lummus Technology has a strong or leading market share in the majority of the technologies we license. In general, this position is the result of superior process performance and minimum capital costs, leading to the best internal rate of return (IRR) for each project. Each technology has specific features that differentiate it from the competitors. To illustrate, we will discuss our ethylene technology.

The production of ethylene and propylene by steam cracking is a fairly mature technology. While improvements in the configuration of the pyrolysis module and the product recovery sections continue to increase the efficiency of the process, the process chemistry and fundamental flow sheet configuration has remained relatively unchanged. With rising crude oil prices and global warming concerns, olefins producers face a number of challenges. One is to reduce greenhouse gas emissions by reducing the fuel fired in the thermal cracking of feedstocks and by lowering the energy consumption of the product recovery section. Another challenge is to lower the significant level of investment associated with new steam cracking facilities. A third challenge is to improve the IRR on these investments by enhancing the product slate produced from thermal cracking, thereby improving the operating margins.

To help meet these challenges, Lummus Technology conducted a research and development program that focused on changing the process chemistry downstream of the pyrolysis module (i.e., the ethylene plant reactor system) and on a fundamental reconfiguration of the steam cracker flow sheet. This program has led to 16 improvements that represent the first fundamental changes in ethylene technology in more than 25 years.

These innovations include several in the pyrolysis module that lower NOx, reduce greenhouse gas emissions, and extend the time between heater decokings. One key innovation is providing the combustion air by using gas turbine exhaust. This integration reduces the overall energy consumption 25% by improving the cycle efficiency.

The ethylene flow sheet innovations include the replacement of the three separate refrigeration systems used in the conventional flow sheet with a single system. This reduces the number of rotating equipment casings by half, thereby lowering investment while reducing maintenance costs and increasing reliability. Applying catalytic distillation to the selective hydrogenation of the acetylenes and dienes permits the combination of the four separate, fixed bed reactor systems into a single reactor, which is then combined with an otherwise required fractionation step. This not only lowers investment by equipment elimination, but also changes the process chemistry by removing up to 35% of the pyrolysis hydrogen by chemical reaction rather than cryogenic separation.

Olefins Conversion Technology (OCT), Comonomer Production Technology (CPT) and Ethylene Dimerization Technology allow even more significant changes to the process chemistry. OCT combines metathesis and isomerization chemistry, reacting the steam-cracker C4s with ethylene to produce propylene in an energy-neutral reaction. This allows for up to 40% of the product propylene to be produced without energy consumption in the reaction step and an increase in the maximum propylene-to-ethylene ratio in a naphtha cracker from 0.6 to 1.1. Utilizing OCT with Ethylene Dimerization Technology provides the only route that produces any required quantity of propylene from ethane feedstock. CPT allows the steam-cracker C4s to be upgraded to butene-1 and hexene-1, the comonomers required for polyethylene and polypropylene. These comonomers are more commonly produced from much-higher-valued polymer-grade ethylene.

These changes in process chemistry, as well as the changes in the pyrolysis module and ethylene flow sheet, can provide significant improvements to the IRR of steam cracker projects while providing a broader range of by-product production rates to help meet changing market demands.

What are the challenges facing your technology business?

As a leading technology licensor, Lummus faces many of the same challenges as our customers. Some of the more important challenges related to technology development include:

• Reduction in greenhouse gas generation
• Minimization of feedstock consumption and/or utilization of alternative feedstocks
• Shift in by-product demands
• Increasing economy of scale

To address these challenges, an ongoing program of technical innovation and new technology commercialization is essential. To illustrate how Lummus is meeting these challenges, we again revert to the core unit in a petrochemical complex – the ethylene plant.

As noted above, Lummus has focused on greenhouse gas emission reduction with several technology innovations. These include:

• Gas turbine integration with the ethylene plant cracking heaters, which improves overall cycle efficiency, reducing energy consumption and the resulting greenhouse gases by 25%.
• The production of propylene utilizing energy-neutral metathesis chemistry. Integration with a steam cracker can reduce energy consumption and the resulting greenhouse gases by 13%.
• Changing the ethylene plant process chemistry with catalytic distillation hydrogenation. This permits the removal of up to 35% of the pyrolysis hydrogen by chemical reaction rather than cryogenic separation, thereby reducing compressor power demands.
• Minimizing feedstock consumption and utilizing alternate feedstocks is another major challenge facing petrochemical producers and technology licensors. Advances to meet these challenges include:
• Production of polyolefin comonomers from lower-valued C4 feedstocks, which permits more product ethylene to be utilized for more valuable ethylene derivatives;
• Utilization of C4s by-products to produce propylene, which reduces fresh feed consumption;
•  Ethylene dimerization combined with metathesis chemistry, which provides the only route to propylene from lower-valued ethane feedstock;
•  Methanol-to-olefins (MTO) technology, which allows lower-valued stranded methane or coal to be the base feedstocks for ethylene and propylene production.

The first commercial scale MTO unit is expected to begin operation in China in third quarter 2010. It will utilize a technology offered jointly by Shaanxi Xin Xing Coal Chemical Science & Technology Development Company (SYN) and Lummus Technology. Once commercially demonstrated, this technology will be a major step forward in providing an alternate feedstock for the production of light olefins.

As downstream product demand shifts, the product mix from the petrochemical complex will need to also shift. As the amount of ethylene produced from ethane and propane increases, the co-current production of propylene will drop. This drop, coupled with a higher growth rate for propylene derivatives, will increase the demand for on-purpose propylene production. This on-purpose demand will be met in part by technologies licensed by Lummus, including OCT and Ethylene Dimerization (discussed above), as well as CATOFIN® propane dehydrogenation and MTO. (The latter produces a propylene-to-ethylene ratio of between 1.0 and 1.2.)

One approach to minimize the capital investment associated with the petrochemical complex is by increasing the economy of scale. Ethylene plants today can produce 1.5 to 1.6 million tons per annum (TPA) in a single train. Developments under way will increase the single-train capacity to over 2.0 million TPA in the foreseeable future. In a similar fashion, Lummus has demonstrated single-train propane dehydrogenation units with capacities up to 650,000 TPA and single train OCT units with capacities up to 800,000 TPA. The capacities of these units will also be increasing to meet this investment minimization challenge.

The final challenge unique to technology licensors is commercialization of the technology innovations necessary to meet the demands facing the petrochemical industry. The magnitude of the investment required, as well as the financing constraints, often causes owners to be reluctant to commercialize new concepts. Lummus has tried to meet this challenge by forming partner relationships with major producers. For the industry challenges to be continually met, these relationships must continue to expand.

Is there any difference between the technology provided for a liquid cracker or a gas cracker?

Ethane-feed crackers can be less complex than propane- and heavier-feed crackers due to the production of fewer by-products. That is, the ethane cracker produces 80% ethylene with the other two principal by-products being hydrogen and methane. Generally, the C3 and heavier products are not produced in sufficient quantities to justify product recovery. On larger scale ethane crackers, the recovery of propylene is typically justified; however, all other by-products are sent to fuel. This can significantly simplify the recovery section of the cracker.

With a growing shortage of ethane feedstock, feed flexibility is becoming increasingly important. If more than 10-15% propane or heavier feed is added to the cracker, by-product recovery is usually justified and the flow scheme becomes similar to the naphtha-feed plant. While the equipment is smaller, the process configuration remains the same.