Liquid hydrocarbon quantity and quality metering unit

Liquid hydrocarbon quantity and quality metering unit is a complex of process equipment and pipeline valves, metering devices, metering results recording, as well as data gathering and processing.
Metering unit is located in block-box or in an open site. Block-box is equipped with ex-proof electrical heaters with automatic control, automated internal gas accumulation control devices, fire alarm sensors, visual and audible alarm unit for fire and gas accumulation, suction-and-exhaust ventilation. 

Unit serves automatic metering of operating medium flow, processed by metering system with required precision and qualitative parameters of operating medium. 

Components composition

Basic metering unit composition:
• filters unit (FU);
• meter run unit (MRU);
• crude quality measuring unit (QMU);
• information processing system (IPS);
• local control system (LCS).
Technological package may also include

• prover;
• flow rate control unit;
• flow rate control unit via prover;
• mobile prover connection unit;
• phase state detector.

Controlled parameters list

• oil flow rate in instrumentation line t/h, m3;
• total flow rate in metering unit t/h, m3;
• oil temperature, °С;
• oil pressure, MPa;
• oil density, kg/m3;
• water volume ratio, %;
• filters differential head, MPa;
• filling ratio of sampler tank;
• liquid flow rate as per oil quality metering unit;
• gas accumulation and fire control inside premise.

Filters unit 

Filters unit serves to separate liquid from mechanical impurities.

Filters unit includes
• filters with quickly removed cap;
• valves for filters deaerating;
• drain gates for liquid discharge from filters;
• local metering devices of filters differential pressure;
• filter pressure differential sensor.

Meter run unit 

Meter run unit serves to meter volumetric and mass flow rate, liquid temperature and pressure inside meter run. 

Process flow diagram provides

• automatic liquid flow rate metering in weight/volume unit systems;
• automatic metering of liquid density, humidity content, pressure and temperature in metering mode;
• automatic and manual liquid sampling;
• flow meter metrological characteristics control according to control flow meter;
• flow meter metrological characteristics control according to prover;
• prover flow meter testing;
• shut off valves sealability control;
• spill, equipment and pipeline drainage products gathering into drain system.

Meter run unit includes

• operating, spare and control (composition depends on customer’s request) flow meters;
• pressure sensor (installed at MRU outlet collecting tank);
• temperature sensor (installed at MRU outlet collecting tank);
• temperature sensor installed at every Metering Run Unit;
• pressure sensor installed at every Metering Run Unit;
• local pressure metering units – pressure guages;
• local temperature metering unit – glass thermometer;
• ball valves at Metering Run Unit inlet;
• ball valves for deaerating of flow rate meters lines;
• inlet collecting tank with ball drain valve;
• outlet collecting tank with ball drain valve;
• closed drain system. 

The following equipment may also be included

• flow control;
• linear compensator.

Crude quality measuring unit

Crude quality measuring unit serves to measure density, humidity content, liquid viscosity etc., liquid representative sample formation.

Crude quality measuring unit includes

• sampling unit;
• automated sampler;
• manual sampler;
• temperature sensor;
• pressure sensor;
• local temperature metering unit – glass thermometer;
• local pressure metering units – pressure guages;
• on-line density transducer;
• in-flow moisture meter;
• flow rate meter;
• flow control;
• ball valves.

The following equipment may also be included

• final filter (operating and spare) to increase service life of high-precision metering devices;
• oil circulating pumps for crude quality measuring unit (if pumping scheme applied);
• viscosity inline transducers (depening on flowmeter type applied in oil metering system);
• inline sulphur meter;
• tie-in for pycnometer unit and nonassociated gas detector is foreseen;
• flushing pump, a tank with flushing liquid, piping.
Most part of devices installed in crude quality measuring unit are duplicated in order to increase unit’s reliability and keep operation status during preventive maintenance activities. 

Information processing system

Information processing system (IPS) calculates flow rate converted to standard conditions, provides protection, acquired data archiving, information transfer to upper level, reports preparation and printout.
IPS is formed with certified flow computers – inline controllers. 

Inline controller

Inline controllers perform main part of commercial oil recording and represent essential equipment of IPS. “Hot standby” may be applied at the customer’s requirement. Operating and spare flow computers synchronously perform the same functions of data collecting and processing.

Local control system 
Local control system (LCS) performs required measuring to control performance of equipment unit, shut off valves and their status control, alarm signals processing and fixation, data transfer to upper level.
LCS is based on programmable logic controller.

Information processing system and local control system together include the following means: 

1) Control cabinet equipped with:
• inline controller;
• programmable logic controller; 
• uninterruptable power system with batteries;
• automatic circuit breaker, drive, intrinsically safe barrier etc;
2) Operator-metrologist’s Automated working station, which includes: computer, display, printer. 

IPS and LCS realize the following functions:

• processing of signals from primary transducers;
• conversion of incoming signals parameters into value of a quantity and their display;
• display and record of metering and process information;
• real-time monitoring of metering line and measuring transducers operating modes;
• SI ratios and constants display, automatic preparation, display and printout of diagrams with measured values (trends);
• personnel warning on production cycle malfunctions and emergency situation (information displaying, audio signal supply, printing out);
• event registration in the log;
• automated control and in-process control of the equipment operation;
• adjustment of operating modes of metering line and metering transducers for crude quality measuring unit;
• shutoff valves control;
• samplers operation control;
• switching between equipment packages;
• Maintaining of main records
• reports (per shift, daily, monthly);
• oil quality certificate;
• delivery and acceptance certificates;
• daily operating log with SI values from metering unit;
• data archiving;
• printing out of records, event logs, inspection and control charts;
• authorized access with password depending on control and operation levels of the program;
• data registration from firefighting automation system, gas content control;
• receipt and monitoring in real time of SI data, non-included in the metering unit (phase condition indicators, pressure transducers, level meters);
• symbolic circuit built-up; 
• creation and editing of report documents patterns;
• protection against unauthorized access;
• Data transfer into receiving (transmitting) party local network following approved exchange protocols.
Metering units are installed on equipment of leading international and russian producers. Equipment design and manufacturing is accomplished in strict accordance with all the technical regulations.
Corporation assets allow to manufacture and configure equipment, meeting to the full customer’s requirements.

Code for order placement of metering unit 

Order placement for Metering unit is done according to ТУ 3667-017-45211680–2007 “Metering system of oil and oil products quantity and quality values. Technical requirements” related to data sheet, which includes additional requirements”.
An example of designation necessary for order placement of Metering system of oil quality with nominal production rate of 100 m3/h and PN of 4,0 MPa: СИКН-100-4,0 ТУ 3667-017-45211680-2007.

An example of process flow diagram for metering line and oil quality control unit

General view of metering line and oil quality control unit