#	Pagina
attuale pagina	/open-h2020/projects/205419/results.html

Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - IMPROOF (INTEGRATED MODEL GUIDED PROCESS OPTIMIZATION OF STEAM CRACKING FURNACES)

Teaser

Summary

The objective of IMPROOF is to drastically improve the energy efficiency of the radiation section of a steam cracking furnace by at least 20%, and this in a cost effective way, while simultaneously reducing emissions of greenhouse gases and NOX per ton ethylene produced with at least 25%.
One of the most important ways to reduce the energy input in steam cracking furnaces per ton ethylene produced is to reduce coke formation on the reactor wall of the long tubular reactors that are mounted in these furnaces. Typically, the outlet temperature of the tubular reactor is very high, around 820 â€“ 890 Â°C. In modern cracking furnaces, the residence time is reduced to a few hundred milliseconds in order to improve the yield of desired light olefins. After the cracking temperature has been reached, the gas is quickly quenched to stop the cracking reaction in a transfer line heat exchanger to recover as much energy as possible. All ethylene furnaces until now have to be decoked after 30-60 days to remove the coke that collected in the coil. When the furnaces are decoked, production of the desired products is stopped for approximately 48 hours. During the course of one run, deposited coke can reduce the heat-transfer efficiency of the firebox by 1-2 %, resulting in a 5 % increase in fuel consumption. The use of either advanced coil materials, combined with 3D reactor designs, improved process control, and more uniform heat transfer could increase run lengths, reducing simultaneously CO2 emissions and the lifetime of the furnaces.
For a straight and a finned coil, an improved geometry can result in shorter radial temperature gradients inside the coil, and thus lower wall temperatures where the coke formation occurs (and thus will be exponentially reduced). The latter will be translated to significant improvement of energy consumption per mass of produced ethylene. In addition, lower tube wall temperature â€“ which results from the improved geometry - will extend the run length resulting in lower energy consumption for decoking the radiant coils an annual basis. IMPROOF will demonstrate the advantage of combining all these technological innovations, with an anticipated increase of the time on stream with a factor 3.
In addition, biogas and bio-oil will be considered because these fuels can be considered renewable, and hence, decrease net CO2 production. It is expected that these fuels will become available in substantial quantities in the near future in Europe. A concern for bio-oil is the possible presence of fuel-bound nitrogen, of which 30% - 50% typically converts to NOx depending on the O2 levels and temperature. Hydro-treated bio-oil will therefore also be considered.
The radiation is emitted by the refractory walls towards the process radiant coils. Application of high emissivity coatings on the external surface of the radiant coils could improve the energy consumption in several ways. In addition, improved emissivity coatings can be applied to the furnace walls. Less firing is required to reach the same process temperatures in the radiant coils. This will reduce fuel gas consumption and CO2 emissions by an anticipated 10 to 15%, at the same time reducing the high-pressure steam generation in the convection section. In addition to higher heat absorption, coating the external surface of radiant coils can improve the surface homogeneity and eliminate hot spots on the tube walls. An additional benefit will be extended run lengths resulting in less energy spent annually for decoking the radiant coils. It is extremely important to select the correct, systematic, specific, strategic objectives for sustainable implementation in complex plant-wide and industrial data-intensive process systems, including all the parameters involved in real-plant conditions.

Work performed

As for WP1, CNRS has started collecting experimental data on biogas, bio-oil and natural gas. POLIMI has performed a literature study, updating their reaction mechanism for different types of combustion. POLIMI and UGENT characterized experimentally the composition of the renewable fuels that will be used within this project. This characterization allowed for the identification of a proper surrogate mixture of a limited number of reference species, whose combustion kinetics will be experimentally and theoretically investigated.
JZHC has designed the plans for the required pilot plant modifications. JZHC has started doing experiments with ambient air and UGENT defined biofuel composition. UGENT has started with the coking experiments on the materials provided by S+C. A testing protocol has been agreed to. In collaboration with S+C and CRESS, initial spectral emissivity experiments have been performed under the supervision of UGENT. High emissivity values are measured, proving the potential for improving energy efficiency. UGENT has started the initial simulations for the S+C SCOPE design, which will be compared to the hot and cold flow experimental data. The hot flow pilot plant experiments are halfway through the first phase where different coil geometries and materials are tested. In the upcoming step different high emissivity coatings will be evaluated.
A CFD framework has been constructed by CERFACS in collaboration with UGENT, this numerical approach will be able to perform high-fidelity LES inside the reactor properly accounting for turbulence and complex chemistry. CERFACS and UGENT have received the reactor geometries that will be simulated within IMPROOF. UGENT and CERFACS have conducted a literature study in order to assess how the spectral behaviour of high emissivity coatings and selective absorption of the gas phase can be accounted for in radiation models.
DOW has selected the furnaces at their Terneuzen site to demonstrate the technologies developed in IMPROOF and has provided the partners the necessary geometric information and operation conditions. DOW has proposed different ways to apply the selected technology from TRL5 pilot and is currently still discussing the implementation of the necessary measurement instrumentation. DOW has developed and shared a project plan. Technip will conduct technology scale up impact analysis including cost scenarios for TRL6 plant to TRL9. Ayming conducted the Innovation Management Internal Benchmark, has initiated an IP watch and updated the project exploitation plan with WP leaders.
AVGI had initiated the benchmarking procedure and has been discussing how to proceed with the LCA specialists in UGENT. They have summarized the current state of the art by determining the current status of development of all partners and other actors in this field which is required for their future evaluation of all expected benefits.
CERFACS has created the IMPROOF project logo, website and first version of the brochure.

Final results

Since IMPROOF has been operative, no wider societal implications of the project have been achieved so far. The socio-economic impact of the project will become clearer once the first results of the simulations and experiments have been discussed within the consortium. Up until this point, the goal was on reaching the initial project objectives. However, the initial results will be presented at various conferences in the upcoming months, showing that the project has already made scientific progress.