Optimising ethylene production with SAM®
The main production method for ethylene is thermal cracking of hydrocarbons in radiant coils suspended in a furnace. Naphtha or ethane often are used as feedstock. The goal is to convert as much of the feedstock as possible to ethylene or other desired products with minimum amount of energy input and a reasonable lifetime of the cracking equipment. One of the main operational parameters to control the conversion is the set point for the coil outlet temperature (COT) of the furnace. This parameter has an effect on the effluent composition, hence the amount of high-value chemicals (HVC) leaving the furnace. Setting the optimal value for the COT impacts directly the revenue stream of the ethylene plant.
The determination of the optimal COT is important since it determines the product yield and consequently the economics of the whole plant. This can be done with the aid of operating data and simulation programs like SPYRO®. The optimal COT for each furnace is calculated based on the combination of:
- Hydrocarbon feed stock analysis
- Operating data retrieved from the control system
- Desired severity of the process.
Considering inevitable measurement errors and finite model accuracy, the process feedback needs to be provided within the simulation program to ensure the achievement of specified severity set point. This feedback loop corrects optimal COT based on actual effluent analysis. This validation process requires time to collect the relevant data, structure the data, execute simulations and interpret the results.
SAM® provides calibrated models for all the furnaces hourly. The model ingests the actual operation conditions such as feed rate, dilution steam, feed composition and COT. This allows SAM® to advise the optimal COT based on the monetary values of the HVC within a few clicks.
SAM® provides the plant’s personnel with operational key performance indicators and analyses of data trends identifying potential capacity, performance and availability issues. It continuously suggests optimization opportunities based on real-time plant data combined with yield prediction and plant optimization via SPYRO®.
The digital service enables plant operators and executives to see a real-time overview of the operation of the furnaces on the ethylene plant for improvement of operation, availability and reliability.