Abdraimova Nurila Ondirisovna, Bainiyazova Akmaral Taskaraevna, Demeuova Akmaral Bahitbekovna

Kyzylorda state university named after Korkyt – Ata

E-mail: Akmabay@mail.ru

Automation and control system tank farm

Abstract

This article comprises data for Delta V visualization system software to control process parameters of the Tank farm using operator workstation. This article shall be used as the operation guide.

This article describes the visualization systems purpose, its capability and function, general rules for operation, operator and other engineers guide to realize various functions.

Introduction

The technology of process instrumentation continues to grow in both application and sophistication. The various control equipment components that may be used to regulate a process and certain aspects of process behavior will be discussed in this article.

Automation consists in the realization of oil storage plant measuring information control system and is based on Fisher-Rosemount HTG oil hydrometer, gagging and record system in tanks. Control system is provided by Delta V full-service distribution system. Field devices, controllers and workstation operate simultaneously consisting of the system, provided each management each on its level.

Insulated Ethernet provides data communication between controllers and workstation is the managing network of Delta V system.

Main Automation Solutions

Tank field site equipped with automation and control system. Two – level hierarchical structural system controls the process. Process variable measurement, transformation of physical magnitude in signals transferring to upper level, characteristics recording, signaling, indication, object positioning, stat using and other operations are fulfilled at the lower level.

HTG system (Fisher-Rosemount) is used for commercial records of oil in PBC-7, PBC-8, PBC-11, PBC-12, PBC-13, PBC-14 tanks. HTG system controls oil weight, volume, density, level and temperature. HTG measurement method is fundamentally differed from other tank hydrometer methods. HTG provides exceptional exact records providing each tank data.

Material weight-to measure directly (total error +/- 0.05%)

Material density – to measure directly(total error +/- 0.11%)

Material temperature– to measure directly(total error +/- 0.11%)

Material level – calculation (total error +/- 0.11%)

Material volume – calculation

Material specific volume +/- 0.11%

Specific density

Weght=(P_bottom-P_Tap)*square

Density=

Volume =

Level =

In addition the system provides all necessary diagnostic information and full signaling (both local and remote for each tank), possible leakage signaling, continuous quality and homogeneity control, allowed load/unload material, field characteristics read etc. altogether 250 characteristics per tank.

The present system is fully automatic one (excluding manual operations and need for density laboratory test), flexible one (has modular construction), open (HART protocol for communication of all intellectual devices, MODBUS RUT protocol for central process unit control by means RS-485 interfaces, PC and FIX MMI package) russified operator interface for Windows NT4.0 communications (factory computer network) and free format report printing, operative one (every second data updating), service-able (no problems w. encapsulation and pollution and no need to be on tank roof), reliable one (lack of moving parts, calibration sensor technology, all system parts error-free running time more than 50 years), mountable (not required to stop tank operation, to empty and air a tank, to take 220V supply for each tank, possibility of daisy chain)

Hydrostatic pressure sensors heating (lower and middle 12 areas in all) is specified for operability assurance in oil tanks during winter by means of self-regulating heating cable Chromatrace. Self-regulating effect lies in the following the lower oil temperature in fitting pipe the larger heat comes from cable and in case of rise in temperature cable ^,s heat-evolution is decreased. One area power input is 17 watt. Maker supplies full outfit kit including termination kit, joints, termination seal and mounting boxes.

«Oil-water» phase division signaling in oil tanks PBC-7, PBC-8, PBC-11-PBC-14 is carried out by level sensors «Zircon» maker Sensall, installed at the level more than 60mm – tank bottom water upper level while tank unloading. Gagging principle is to gage sensor-level permittivity. Sensor sends active part wet-dry signals and self-control sensor signals in two-wire circuit 20mA.

Oil overflow upper level alarm in tanks PBC-7, PBC-8, PBC-11-PBC-14 shall be done by level sensors «Sapphire» maker Sensall, installed at limit filling level. Gagging principle is to change propagation of ultrasound between sensor detectors. It sends active part wet-dry signals and self-control sensor signals in two-wire circuit 4-20mA.

For water level control in water tanks PBC-9, PBC-10 the following system is provided.

- in water tank PBC-10 for water overflow level maker Sensall are applied

- in water tank PBC-9 maker Krohne reflexive action radar oil level sensor is applied owing to trapped oil

- PBC-9, PBC-10 water tank temperature control is carried out by thermo elements with unified output signal and are provided water temperature measurement. The supplier is Metran product group.

Controller fulfills all I/O signal pickup logical operations and process management operations in case of need. Fiber optic cable connects controller with Delta V work station through Ethernet. Field instrumentations installed on oil and water tanks directly. Delta V system work station installed in control room.

Figure 1. Tank Farm Instrumentation.

Summary

The typical process plant contains many tanks, vessels, and reservoirs. Their function is to store or process materials. Accurate measurement of the contents of these containers is vital. The material in the tanks is usually liquid, but occasionally it may consist of solids.

Initially, level measurement appears to present a simple problem. However, a closer look soon reveals a variety of problems that must be resolved. The material may be very corrosive; it may tend to solidify; it may tend to vaporize; it may create other difficulties.

Bibliography

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2. Shinskey, F.G. Process control systems. New York: McGraw-Hill Book Company, 1979.

3. Liptak, B.G. Instrument Engineers Handbook, vols. I and II. Radnor, PA: Chilton Book Company, 1970.

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5. Коршак А.А., Шаммазов А.М.Основы нефтегазового дела. Уфа, 2007.