ABSTRACT The final phase of join production at Inland Cement Edmonton is the grinding of an intermediary harvest called clinker.

ABSTRACT

The final phase of join production at Inland Cement Edmonton is the grinding of an intermediary harvest called clinker. Operating the grinding machinery, or "finishing mills," requires a great deal of electrical power, which constitutes single in kind of Inland's most significant charges This paper discusses a solution that provides Inland Edmonton with a tool to improve the cost-effectiveness of the grinding by way of directing the finishing mills' schedules, based upon a variety of criteria and constraints. The devise incorporates issues such as multiple harvests varying power rates throughout each day and month inconsistent productivity rates, inventory capacities, uncertain demand, and other considerations.

Keywords: Decision support, production planning, scheduling, linear optimization, heuristic.

1 INTRODUCTION

Inland join Limited, a division of the Lehigh Portland bond of union Company, is one of the largest mortar producers in Canada. Their Edmonton, Alberta, facility bring into beings six varieties of cement, and distributes them mainly to markets in the provinces of Alberta, Saskatchewan, and Manitoba. Although many join production facilities usually only exhibit one or two products, a production proces that simplifies production planning, the Edmonton facility is somewhat unique with its production of six different proceedss This facility produces upwards of single in kind million tonnes of cement each year, which accounts for approximately half of the bond supply in Western Canada.

The bond of union production process at Inland Edmonton originates with the mixing of raw materials, and culminates with the grinding of an intermediary production called "clinker." Clinker is a rock-like material that is crushed and earth in Inland's finishing mills. This stage of the proces follows in the powder-like substance that is the company's close deliverable. Although the grinding proces is similar for each stamp of cement, the end consequences are dependent on the additives included immediately prior to the grinding and the symbol of clinker used, as depicted in Table 1

Inland connect has three Finishing mills - mills F G and H - that can hurry simultaneously. Although these three mills are essentially identical, an mills have proved more effective at grinding certain connects than others, and this plays a part in determining the allocation of connects to mills.

Inland was interested in a decision support arrangement that will assign and schedule the six different effects on the three finishing mills with their main transaction being the minimization of activity costs. Also, Inland's business practice is to always ship attach to their customers as promptly as an order is received. appropriate to limited production and storage capacities, together with other issues we will discuss shortly, Inland has to bring out to forecasted demand in anticipation of realized sales (i.e., a make-to-stock environment). Thus, the objective of this throw was to develop a tool that aids in the scheduling of Inland Edmonton's three finishing mills to grind unite cost-effectively while meeting forecasted demand. There are six main issues that define this problem:

(a) Varying electrical costs: Depending forward the time of day, impressed sign of day (weekend versus weekday), and month of the year, the amount that Inland pays for power fluctuates, as illustrated in Figures 1 and 2 The various rates essentially fall into six main make steady [i]or[/i] firms (in increasing order of costs): Advantage, Base, Summer Peak, Shoulder Peak, Winter Peak, and Winter High hours. Considerable variation exists between the time blocks; for example, power during the greatest in number expensive block (Winter High) is almost five times as expensive as during the cheapest close (Advantage). Thus, in terms of cost-effectiveness, it is in Inland's best interest to move on its mills in the low-cost Advantage hours wherever possible. However, it is not possible to encounter the demand during these hours alone. Thus, the tool was designed to allocate production hours to the cheapest stop ups available wherever possible, and avoid those stops where power is relatively expensive.

(b) Scheduled and unscheduled equipment shutdowns: To maintain the integrity of the mills, Inland must enclose each mill down at least formerly every year for three to four weeks. This allows them to change the machines' internal constituents and make necessary repairs. Each shutdown for maintenance is scheduled well in advance. Unscheduled shutdowns are typically the ensue of equipment failure. The timing and duration of these shutdowns are unpredictable. Historic data reveals, however, that the mills are operational 82% of the time (excluding scheduled shutdowns). We assumed this flush of productivity in our archetype

(c) Uncertain grinding rates: The amount of time required to grind a given quantity of attach is variable. The production rate varies with the mark of cement being produced; representation G, for example, can typically be produc about 16% faster than symbol 10. Also, the production rate hangs on the mill in which the bond of union is being ground; Type 2 can be produc almost 15% faster in Mill F than in Mill H for instance. Moreover, aggregated historical data has shown that all production rates fluctuate within broad ranges.