Cracking-plant capacity

The quantity of coproduct acetylene produced is sensitive to both the feedstock and the severity of the cracking process. Naphtha, for example, is cracked at the most severe conditions and thus produces appreciable acetylene up to 2.5 wt % of the ethylene content. On the other hand, gas oil must be processed at lower temperature to limit coking and thus produces less acetylene. Two industry trends are resulting in increased acetylene output (/) the ethylene plant capacity has more than doubled, and (2) furnace operating conditions of higher temperature and shorter residence times have increased the cracking severity. 

Both production sites produce basic and intermediate chemicals based on Naphtha. However, both sites focus on different final products. They also vary in their plants capacities. The Naphtha is. steam-cracked at both sites with similar plant configurations. Hence, the ratios of output flows are. similar but the heights of the flow rates are not. 

Lee et al. (2007) reported a successful retrofit project for an Asian ethylene plant. This retrofit case went through every single phase of feasibility assessment and retrofit design. Initially, the plant management had a two-phase retrofit strategy for capacity expansion, namely, 10% increase in the first phase (to be implemented in the forthcoming turnaround) and 20% increase in the second phase. The limit for 20% expansion was set by the cracking furnace capacity. 

Electric Discharge Processes. The synthetic mbber plant built by the 1. G. Farbenindustrie during World War 11 at Hbls, contained the first successful commercial instaUation for the electric arc cracking of lower hydrocarbons to acetylene. The plant, with a capacity of 200 t/d, was put into operation in August 1940. 

Some invaluable isolated actions were taken from time to time in the last twenty to twenty five years that prevented air quality from declining at an even faster rate. For example, energy demand was met (electricity and refined oil products) by expanding capacity of plants located outside of the MCMA a metro was built the vehicular traffic system was reordered and new hydrotreating, reforming and catalytic cracking units reduced lead and sulfur in refined products. 

Commercial plants Technip has been awarded four ethylene plants ranging from 500 kty up to 1,400 kty using either ethane or liquid feedstocks. While over 300 cracking furnaces have been built, and 15 units operate worldwide, numerous expansions over the nominal capacity based on progressive separation techniques are under way, with up to an 80% increase in capacity. For ethane cracking, front-end hydrogenation scheme is also available. 

Of the more than 40 US cracking operations, most are world scale with an average capacity of over 700,000t/y. The US has some of the largest plants in the world with several in excess of 1 million tonnes and one with over 2 milUon tonnes capacity. Table 1.1 gives a list of the ethylene cracking operations, the operators, their location and nameplate capacity in 2008. 

The plant locations and capacity are listed in Table 1.7. Most of the Chinese plants are old, with capacities below 200,000 t/y. Many of these plants were designed to use gas-oil and naphtha as feedstock. This takes advantage of some of China s indigenous crude oil, which have high levels of paraffin wax in the gas-oil fractions. In steam cracking, such gas-oils give high yields of ethylene and propylene. Newer plants... 

This is a fluid-bed cracking process. It was first tested in 1990s. This pilot plant has a 400 tonne per year feed capacity, but runs continuously on a 50 Kg/h scale as it has limited product storage. The next steps in the development process to follow are optimization and scale-up. 

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