Understand the Drag Reducing Agent (DRA) Injector application

The Drag Reducing Agent (DRA) Injector application manages the complexities associated with injecting DRA into a pipeline. Complexities include monitoring which products are upstream on their way to the injector (and thus should be checked for DRA compatibility), the rate at which DRA should be injecting, and checking the density of the current product being injected into against the densities of known DRA-incompatible products. In addition, the DRA Injector application is capable of monitoring a status or multistate point to gather information on violations found by third-party applications.

Up to four volume sources can be associated with a single DRA injector. In addition, it can use up to four sources of flow rates in order to perform flow rate limit checking. A Rules Validation Engine (RVE) rule (and corresponding Business Logic Tier [BLT]) can be configured for an injector source record to determine whether pumping a DRA is acceptable or not.

The primary objectives of the DRA Injector application are as follows:

• Set the injection rate so that the targeted DRA concentration of the fluid in the pipeline is achieved.

• Alarm, shut down, or block DRA injection if a violation condition exists.

There are two types of violations:

• Prohibited product. A violation exists whenever a product prohibited for any DRA additive is present at an active DRA injection location or is separated from an active DRA injection location by a fluid buffer of insufficient volume.

• Device restrictions. This occurs only when the application is managing the injection rate.

  • If flow rate at the injector location is less that a configured minimum, a violation exists.

  • If the target DRA concentration is set to zero ppm (or less), a violation exists.

Key Concepts

• Configuration data and runtime data for the location is contained in the DRAInjector table.

• A DRA Injector device can have two points of control:

  • A status or multistate point used to start and stop the DRA pump.

  • Optionally, an analog point used to set the injection rate.

• While running or when starting up, checks are made for violations due to a prohibited product and violations due to restrictions on the device itself.

Key Tasks

• Configuration of the DRA injector.

• Provision of product information, including product location with respect to the injector.

• Understanding the rules under which DRA injection is allowed.