Add shipment loss stream using minimum range constraint

Assume that there is a shipment from the TK1 tank in the current period.

The following procedure describes how to add a shipment loss stream:

1. Add the required intermediate node and final shipment

2. Add the transaction stream (TR_TK1) from the tank to the intermediate node

3. Add the shipment stream (SS_TK1) cotransactionnnecting the node to the shipment

4. Change the end inventory of the TK1 tank from 70 ton to 65 ton. This indicates that 5 tons were shipped from this tank.

   Since the SS_TK1 shipment stream is an accounting shipment point, the tolerance of this stream is defined as zero and the shipment amount is therefore exactly 5 tons.

5. Define the type of the TR_TK1 stream to be . Set the movement start time to be 12:00 PM of the current date and the end time to midnight (12:00 AM of the next day).

Define amounts as rates or absolute quantities

When dealing with transactions, the issue of absolute quantity amounts versus flow rates arises. AVEVA Production Accounting allows you to specify on the Utility tab of the Option dialog (under Tool>Option) whether or not you wish amounts on dialogs and on spreadsheets should be displayed as rates (per unit of time) or absolute quantities. The two relevant checkboxes are:

• Use Quantity instead of Flow Rate in Display and Report

• Use Quantity instead of Flow Rate in stream dialog box

Let us assume that your Option settings indicate that you use flow rates on your stream dialog box. (This is the initial setting delivered with AVEVA Production Accounting.) For this tutorial, we wish to have a movement of 4.8 tons. This transaction lasts for 12 hours (a half day). Therefore, input a flow rate of twice the desired transaction amount, or 9.6 ton/day.

Add a shipment loss stream (LOSS_TK1) coming from the node that leads to the shipment. Mark this stream as unmeasured with a 0.1 ton/day minimum flow rate.

The flowsheet is changed as shown below.

During data reconciliation, the shipment loss stream (LOSS_TK1) is treated as in service and the reconciled value is set to -0.214 ton/day. This means the imbalance between TR_TK1 and SS_TK1 is over the minimum range ( ±0.1 ton/day).

To illustrate what happens when the loss is considered to be within the minimum (close enough to zero to ignore), change the minimum rate of this shipment loss stream (LOSS_TK1) changed to 0.3 ton/day from 0.1 ton/day. Run data reconciliation again.

The shipment loss stream (LOSS_TK1) is then treated as out of service because its effective flow rate is 0.

The color of this stream is turned to red and the solvability is "COS (Out of Service Flow by Minimum Constraint)".

The TR_TK1 transaction stream is reconciled to match the SS_TK1 shipment stream regardless of the measured value.

This configuration of the minimum range of the receipt/shipment loss stream is useful in loss summary of each receipt and shipment point. It draws attention to discrepancies that may mean that the receipt of shipment meter might be miscalibrated or that there is a missing movement. If the reconciled consumption/production value from the process balance is within the minimum range with respect to the receipt/shipment value, the receipt/shipment loss stream is marked as out of service and the consumption/production value is reconciled from the receipt/shipment value. If the discrepancy is over the minimum range, the receipt/shipment loss stream is treated as in service and receives a value, which draws attention to the problem.