ModelEnterprise case: Optimal scheduling of a specialised refinery

Meeting deliveries, optimizing stocks and reducing cash flow

Fig. 1 – Petrochem Carless production network – click to enlarge

"A key result was improved financial management through better cash flow"

Generic process resource-task network (RTN) – click to enlarge

Fig. 2 – Generic process resource-task network (RTN)

Gantt chart showing annual production plan – click to enlarge

Fig. 3 – Gantt chart showing annual production plan

Gantt chart showing detailed monthly production schedule – click to enlarge

Fig. 4 – Gantt chart showing detailed monthly production schedule

Petrochem Carless is a specialty hydrocarbon refining company. Its turnover in 2002 was £225m.

Its facilities primarily use North Sea condensate as input material and produce a variety of products including high performance (e.g. Formula 1) fuels, solvents, drilling fluids, printing ink distillates, white oils and additives.

Objectives

The company approached PSE because it wanted to:

schedule more effectively
meet deliveries with increased confidence
achieve target stocks for following month
reduce cash-flow in purchasing raw materials
reduce effort in scheduling and planning
replace their existing tool – which did planning only – with a single model-based tool for both planning and scheduling.

PSE approach

PSE worked with Petrochem Carless to construct a model of the company's operations and provide facilities to integrate the model seamlessly with existing systems and workflows.

The model

A networked model was developed which allowed different sites and headquarters to develop plans.

The model includes several major processes, various receiving terminals, over 100 products and a similar number of other materials, and nearly 100 storage tanks. It also accommodates bonded storage.

The application optimises cash flow by efficient planning of purchases and inventory aligned with the process schedule. An annual plan is updated every month, and then the first month is scheduled in detail.

All results are presented in Gantt charts and Excel sheets, making it easy for personnel to access information in a familiar and intuitive form.

Integration

The application was integrated with the ERP system (BPCS) to tie in with inventory and financial planning.

A customised Excel based user interface for data input was developed using the ModelEnterprise VBA automation library. This allows the end user to keep working in a familiar environment, using only the data readily available from the plant, sales and procurement.

Once the required data are available, the application:

calculates all the necessary parameters
builds the appropriate model automatically in ModelEnterprise
executes the model in the background
sends post-processed results back to Excel.

Benefits

The benefits were twofold:

Improved financial management through better cash flow. Seasonal materials are purchased optimally and seasonal products are produced at the right time, freeing up substantial amounts of money for alternative investments.
Reduced cost of ownership: the company no longer needs two separate tools for planning and scheduling and were able to stop paying the licence fee for a legacy tool.