HYDROCOM - FOR RECIPCOMPRESSOR

General Description 4.01.doc 2008-04-09

HydroCOM

Edition 4.01

General Description HydroCOM 4.0

makes compressor control

and monitoring an easy job

General Description 4.01.doc 2 2008-04-09

1 INTRODUCTION ...................................................................................................3

2 ABBREVIATIONS.................................................................................................3

3 GENERAL FUNCTION..........................................................................................4

3.1 What is HydroCOM?...............................................................................................................................4

3.2 Functional description ...........................................................................................................................5

3.3 The reverse flow control ........................................................................................................................6

3.4 Control layout .........................................................................................................................................8

3.5 Certificates and approvals .....................................................................................................................9 3.4.1 Explosion protection..........................................................................................................................9 3.4.2 Electromagnetic Compatibility (EMC) and safety of low voltage devices ..........................................9

4 THE COMPONENTS OF HYDROCOM...............................................................10

4.1 HydroCOM actuators............................................................................................................................10

4.2 Compressor Interface Unit CIU............................................................................................................11

4.3 External Power Supply.........................................................................................................................12

4.4 Isolation Amplifier ................................................................................................................................12

4.5 TDC-sensor ...........................................................................................................................................12

4.6 Hydraulic Unit (HU)...............................................................................................................................12

4.7 HydroCOM Service Software (HSS) ....................................................................................................14

4.8 Fast-TIM.................................................................................................................................................14

4.9 Compressor Condition Monitoring (RecipCOM)................................................................................15

4.10 Rod-Position Analyser (RPA) ..............................................................................................................17

5 INSTALLATION EXAMPLES..............................................................................18


1 Introduction This document describes the functions and equipment of HydroCOM in general. The equipment delivered may slightly differ from the descriptions in this document.

2 Abbreviations The following abbreviations are used throughout this manual Actuator Device for suction valve control CIU Compressor Interface Unit RecipCOM Compressor Condition Monitoring DCS Distributed control system EPS External Power Supply, 48VDC Fast-TIM Transmitter Interface Module: Decentral data

acquisition device for fast and slow signals DCS Distributed control system GIM General Interface Module HydroCOM-RecipCOM On-line compressor condition monitoring system HSS HydroCOM Service Software HU Hydraulic Unit IA Isolation Amplifier IPS Internal Power Supply OPC OLE for process control PLC Programmable logic controller RPA Rod Position Analyser for rider ring wear and run-out

monitoring SIM Stage Interface Module TDC Top Dead Center


3 General function 3.1 What is HydroCOM?

The reliable, efficient, flexible compressor control system for optimal use of resources. HydroCOM is a hydraulically actuated computerised compressor control system. HydroCOM is a system for the stepless capacity control of reciprocating compressors in a range between (0) 10 -100 %. The minimum continuous load depends on gas composition, operating conditions and compressor design parameters. HydroCOM is based on components of the injection technology for large diesel engines, enhanced by state of the art digital computing and control technology. Hydraulically actuated unloaders keep the suction valves open during part of the compression cycle. Thus part of the gas taken into the cylinder during the suction cycle is pushed back into the suction plenum. In this way the gas volume per working stroke can be controlled. This system saves compression power at part load, since the energy consumption of a compressor is proportional to the quantity of gas compressed per compression cycle. The capacity closed loop control is done by the DCS / PLC or an optionally supplied loop controller. HydroCOM provides in addition to control as a standard feature suction valve nest temperature measurement. Temperature sensors are integrated in each actuator. HydroCOM 4.0 is a control and monitoring platform. Fast-TIMs can not be only used for temperature and rider ring wear monitoring. On top of that the on-line compressor condition and performance monitoring system, HydroCOM-RecipCOM, can be installed. Fast-TIMs feature decentralized data acquisition and bus communication. They are designed to be installed at or close to the compressor and save field wiring and installation costs.


3.2 Functional description The following diagram shows the schematic layout of HydroCOM and the optionally supplied Fast-TIMs and the on-line monitoring system, HydroCOM-RecipCOM:

Fig. 1.: Schematic system layout

All suction valves are equipped with HydroCOM actuators. They perform the actual control task – delaying the closing of the suction valves at part load. Hydraulic unit (HU) and hydraulic piping supply the mechanical energy to the actuators. The actuators are connected by the HydroCOM-Bus to the Compressor Interface Unit (CIU). The CIU provides the electronic control of the actuators and serves as interface between the HydroCOM system and DCS / PLC where closed loop control is performed. The communication between DCS, PLC or loop controller and HydroCOM is based on analog and binary signals. As alternative the on board Modbus interface can be used. HydroCOM 4.0 features data acquisition of fast signals and can be upgraded into a monitoring platform. The measurements can be read as analog signals or via the digital Monitoring Interface (Modbus). If the on-line compressor condition monitoring system HydroCOM-RecipCOM is installed, the CIU is the interface for the RecipCOM-PC. The TDC-sensor synchronizes CIU with compressor speed and gives reference of the crank shaft position. The CIU performs the real time calculation of suction valve opening and closing time and sends the commands to the actuators. Thus compressor output becomes a simple analog control variable for the plant operator. By using digital control technology the HydroCOM system can react within 3 revolutions to change compressor output. Therefore HydroCOM is the ideal choice for those applications where fast and precise control is required. HOERBIGER engineers use the Windows® based HydroCOM Service Software (HSS) for system configuration. But the HSS is also an comprehensive user tool for data display and HydroCOM service.


3.3 The reverse flow control The capacity control method is based on the so called reverse flow control principle. A portion of the gas which was taken into the cylinder during the suction cycle is pushed back into the suction line during the compression cycle.

Fig. 2.: The principle of reverse flow regulation

The above indicator diagram shows the functional principle of HydroCOM. Cylinder pressure is displayed as pV-diagram. At position C (bottom dead center, BDC) the compression cycle starts. Without the HydroCOM system, under full load operation, the gas is compressed immediately after passing BDC. When the cylinder pressure reaches D the discharge valve opens. The gas is pushed out of the cylinder. When the piston reaches A (top dead center, TDC) the re-expansion begins. The gas which due to the cylinder clearance is still in the cylinder, re-expands. When the cylinder pressure reaches the suction pressure (B) the suction valve opens and gas is taken into the cylinder. The power necessary for the operation of the compressor is proportional to the area enclosed by the indicator pressure curve.

Fig. 3.: HydroCOM Actuator The suction valve sealing elements are controlled by the unloader. The unloader is driven by the HydroCOM actuators. In the actuator a fast switching solenoid is foreseen. Just before suction valve opening the

p

V

A D

C

B

Cr

Dr

p D

p S

Energy savings at 50% part load

Check valve

Check valve

Solenoid valve

Solenoid valve

UnloaderUnloader

Suction valve

Suction valve

Hydraulic cylinder

Hydraulic cylinder

Hydraulic unitHydraulic unit


solenoid switches and hydraulic oil flows into the actuator’s hydraulic cylinder. The high pressure piston moves the unloader downwards the valve guard. After BDC the unloader delays the closing of the suction valve during compressor part load. Thus cylinder pressure follows from C to Cr instead of from C to D. The required power consumption is therefore much lower than at full load. The slight pressure increase ( C - Cr) is due to pressure losses in the suction valve. As the gas flows back from the cylinder chamber into the suction line, the quantity of gas in the cylinder available for compression is reduced. At Cr the solenoid switches, oil flows out of the hydraulic cylinder, the unloader moves upwards and the suction valve closes. The compression follows the line from Cr to Dr. As shown in the diagram the indicated power for app. 50% load is only about half of the power required for full load. Thus the principle of reverse flow regulation saves energy compared to bypass control.


3.4 Control layout The compressor is either controlled by the DCS, PLC or an external loop controller that may be optionally provided by HOERBIGER. One of the process variables (e.g. discharge pressure, suction pressure, flow volume..) is selected as control variable. The user defines a set point for this variable. A PI-controller is assigned to each stage of the compressor. The first stage is controlled according to the process variable. The output of the first controller operates primarily the first stage. The interstage suction pressures are selected as control variables for the higher stages. The capacity delivered by each stage is varied by 4..20mA controller signals which are linked to the CIU. The enclosed basic sketch shows this principle. A start-up function is to be provided in the controller. It includes the start-up unloading and start-up ramp for smooth loading of the compressor. Optionally HOERBIGER may give assistance in the DCS/PLC configuration or may deliver a programmed ABB loop controller.

PLS /

Saugdruck

1.

Stufe

PI-Regler

1. Stufe

PT

Start Rampe

Skalierung

1.

Kompressorstufe

CIU SIM 1

Set Point

Saugdruck

2.

Stufe

PI-Regler

Skalierung

2.

Kompressorstufe

Set Point

2. Stufe

PT

CIU SIM 2

DCS / SPSS

uctio

n P

ress

ure

1. S

tage

PI-Controller

1. Stage

PTPT

Start Ramp

SkalierungScale

1. C

ompr

esso

rSta

ge

CIU SIM 1CIU SIM 1

Suc

tion

Pre

ssur

e 2.

Sta

ge

PI-Controller

SkalierungScale

2. C

ompr

esso

rSta

ge

2. Stage

PTPT

CIU SIM 2CIU SIM 2

0 – 100 %0 – 100 %

4Signal

– 20 mA4Signal

– 20 mA

Fig 4.: principle of suction control


3.5 Certificates and approvals

3.4.1 Explosion protection The compressor must not be operated with other gases than specified at the time of placing the order. If the compressor shall be operated with other gases written approval has to be obtained from HOERBIGER. The certification is based on the directive 94/9/EC (ATEX) - Equipment and protective systems intended for use in potentially explosive atmospheres. Standards: electrical apparatus for explosion hazardous location EN 50014 general regulations EN 50018 flame-proof enclosure „d“ EN 50019 type of protection "e" Additionally for the Fast-TIMs: EN 50020 type of protection „i“ Since most HydroCOM applications are installed in potentially explosive atmospheres, all components that are to be installed at the compressor are explosion proof. The explosion protection certification is valid for all gases of the explosion groups IIA and IIB plus hydrogen. The certificate does not allow operation with Oxygen or Acetylene.

In detail following protection classes are used:

• Protection class EEx-d is applied to the actuator’s electric housings where the valve electronics, the solenoid and the hydraulic piston are placed.

• EEx-e is applied to the connection box and the construction of the

solenoid. Exception: The connection box for CSA and FM Div. 1 is EEx-d

• The electric housing of the Fast-TIM is built in protection class EEx-d. The connection box for power supply and field bus connection is designed as per EEx-e. The connection box for connecting the transmitters is supplied as per EEx-i.

Conformity with European Directives is based on a type examination by a Notified Body, the required production tests, and the marking on the device. Following certifications have been received up to now for the actuator: EU: ATEX certified : Electrical Ex-protection: II 2G EEx de IIB+H2 T4 Mechanical Ex-protection: II 2G c USA (FM): AEx de IIB+H2 T4 Class I, Div. 1, Group B, C, D, T4 Canada: Class I, Div. 1, Group B, C, D (CSA) Japan: Ex de IIB + H2 T4 The Fast-TIM can be marked as follows : EU: II 2G EEx e d [ia] IIB+H2 T4 USA+Canada: Class I, Div1, Groups B, C, D, T4 (FM + CSA)

3.4.2 Electromagnetic Compatibility (EMC) and safety of low voltage devices

HydroCOM complies with the EMC regulations and the safety regulations for low voltage devices.


4 The components of HydroCOM Figure 1 outlines all components and supply lines of the HydroCOM system. The components are described in the following sections. • HydroCOM Actuators • Compressor Interface Unit (CIU) • External Power Supply (EPS) • Isolation Amplifier (IA) • TDC-sensor • Hydraulic Unit (HU) • HydroCOM Service & Configuration Software (HSS) • Transmitter Interface Modules (Fast-TIMs) and HydroCOM-RecipCOM

4.1 HydroCOM actuators The HydroCOM actuators control the valve unloaders and thus control the compressor suction valves. The hydraulic pressure is supplied by the hydraulic unit (HU). The actuators are electronically controlled by the CIU via the real-time HydroCOM field bus. Each actuators is supplied with 48VDC by the external power supply (EPS). The actuators comprise of the valve housing, the seal housing and the electric housing.

Seal HousingLeakage out

Flare connectionWiper rings

Guiding ringsSealing rings

Temperature sensor

Seal HousingLeakage out

Flare connectionWiper rings

Guiding ringsSealing rings

Temperature sensor

Valve HousingOil inlet

SolenoidValve cartridge

Soft touch damperOil outlet

Piston cartridgeHigh pressure piston

Valve HousingOil inlet

SolenoidValve cartridge

Soft touch damperOil outlet

Piston cartridgeHigh pressure piston

Electric HousingConnection boxPrinted circuits incl.Microcontroller andValve driver, Fuses, Bus Interface

Electric HousingConnection boxPrinted circuits incl.Microcontroller andValve driver, Fuses, Bus Interface

Unloader RodUnloader Rod

Fig 5.: The HydroCOM Actuator

In the valve housing the 3/2 way valve is actuated by the solenoid and the retracting spring. Depending on the position of the 3/2 way valve the actuator piston is either exposed to the pressure maintained by the hydraulic unit or to atmospheric pressure (tank). The high pressure of the actuator acts directly on the unloader rod. Up streams of the 3/2 way valve a check valve is located. During the phase of reverse flow through the suction valve the hydraulic oil is trapped by the check valve. Consequently the pressure in the high pressure cylinder can exceed the pressure of the hydraulic unit. A two stage throttle (soft-touch-damper) is installed in each actuator in order to protect the moving parts of the unloading system and the valve sealing elements against excessive impact stress. The soft-touch-damper consists of a start bypass volume and an orifice. The bypass volume is filled during the first phase of the closing operation ( 30% to 60% of the valve lift). After the bypass volume has been filled up the oil pressure increases and


dampens the closing of the sealing elements considerably before hitting the seat. The seal housing provides the sealing of the unloader rod. Sealing is performed by a wiper element, several sealing elements and guiding rings. Between the upper and lower sealing element a ring chamber with flare gas connection is located. A temperature sensor is located within this seal housing with the sensing point very close to the suction valve cover. The suction valve cover temperature is used for continuous monitoring of suction valves and flow regulation. The measurements can be transferred via CIU analog outputs or Modbus interface to the DCS/PLS or HydroCOM-RecipCOM. During operation some oil may gather at the bottom of the piston. The oil leakage is tapped by a leakage oil connection into a collecting tank. The actuator electronics are mounted within the flameproof electric housing (EEx-d). The electronics control the solenoid, measure the valve nest temperature and hydraulic pressure (option). Each Actuator is equipped with a microprocessor to fulfill these tasks. This microprocessor solves drive, monitoring, and communication functions. The electrical lines (48VDC and HydroCOM field bas) are connected the EEx-e connection box.

4.2 Compressor Interface Unit CIU

Fig. 6.: Front view HydroCOM-CIU

The HydroCOM-CIU (Compressor Interface Unit) serves as interface between the HydroCOM-system and the DCS / PLC. The controller output defined for each compressor stage is translated into the opening and closing signals for the suction valves. The valve nest temperatures, measured by the actuators, are transferred to the DCS / PLC via the CIU. Further the transmission of enable-, warning-, error- , and simulation signals is effected by the CIU. The CIU is configured and serviced via the RS-232-Interface. The interface is mounted on the front of the CIU. The TDC sensor synchronizes the CIU with compressor speed and crank shaft position. The CIU calculates the valve actuation timing. Signals between CIU and the controller can be exchanged via parallel wiring (hardwired) or Modbus. The Compressor Interface Unit consists of up to six Stage Interface Modules (SIM - one for each compressor stage), the General Interface Module (GIM) and the Internal Power Supply (IPS). The modules are placed in a 19" sub-rack. Up to eight valves as well as up to two Fast-TIMs can be controlled per SIM. Head-end and crank-end valves can be driven independently. There must be one HydroCOM field bus line to the compressor per SIM. Please refer to the assembly manual for the specification of the bus cable. Fast-TIMs for fast signals like indicator pressure and rod position are to be connected to a separate SIM.

HOERBIGE

SIM-4

Code

Scroll/ Clear

HOERBIG

IPS

15V

5V

HOERBIG

HydroCOM

CIU-4

HOERBIGE

SIM-4

Code

Scroll/ Clear

HOERBIGE

SIM-4

Code

Scroll/ Clear

HOERBIG

GIM-4

CIU on TDC Enable

Warning Error

HSS

P low hyd

Simulation


4.3 External Power Supply The External Power Supply (EPS) provides actuators and Fast-TIMs with 48VDC.

4.4 Isolation Amplifier The isolation amplifier transfers the TDC signal from the hazardous area (intrinsically safe circuit) to the CIU in the safe area. Input, output and supply voltage are electrically isolated from each other.

4.5 TDC-sensor The TDC-sensor synchronizes the HydroCOM system with compressor speed and determines the position of the crankshaft. Each revolution the TDC-sensor sends one reference impulse to the CIU. CIU and TDC-sensor are electrically separated by the isolation amplifier IA. The TDC-Sensor is a cylindrical, inductive proximity switch according to DIN 19234 (NAMUR).

4.6 Hydraulic Unit (HU) The Hydraulic Unit supplies hydraulic energy to the actuators. Depending on the suction pressure of the highest controlled compressor stage the pump increases oil pressure from atmospheric pressure to up to 200 bar. The oil is fed to the actuators via hydraulic lines that can be shut-off. There are pulsation dampers close to inlet and outlet of the valves. The oil is led back un-pressurized. Besides the oil supply lines a leakage oil line has to be connected to a separate collector tank. (The specification of the piping system can be found in the assembly and installation manual). The drawing below shows the basic design of the hydraulic unit. Hydraulic oil is pumped via a gear pump into the system. The oil is connected to the circuits of each stage via redundant high-pressure-filters with check valves (visual blocking indication). For each compressor stage one circuit is used. The maximum operating pressure is maintained through a pressure control valve. Any overflowing oil is cooled down in a cooler and is sent via a return filter to the tank. By a built in thermostat the oil cooling circuit will be switched off at low ambient temperatures to avoid too low hydraulic oil temperatures. Following additional equipment is integrated in the hydraulic unit:

• Level switch • Oil pressure transmitter • Temperature transmitter

Optionally an oil pan can be supplied.


Fig. 7.: Hydraulic unit size NG120 (left) und size NG 63 (right)

Fig .8.: Hydraulic unit principle design

Oil tank

Shut-off ball valvesReturn line

Pressure relief valve

Oil level display

Pollution display

Return filter

Shut-off ball valvesFeeding line

Pressure gauge

Switch-over highpressure double filter

Pollution display

Motor

Oil cooler with fan

Airing filtre for tank

Filling filtre for tank

Temperature transmitter

Drain valve

Bypass fordetensioning HU

Supply lineto the Actuators

Return line from the Actuators

10µm

3µm 3µm

max

min

M10µm

500µmTT

PT

LS

°C

Oil pump

Level switch

Pressure transmitter

Thermostat

Oil tank

Shut-off ball valvesReturn line

Pressure relief valve

Oil level display

Pollution display

Return filter

Shut-off ball valvesFeeding line

Pressure gauge

Switch-over highpressure double filter

Pollution display

Motor

Oil cooler with fan

Airing filtre for tank

Filling filtre for tank

Temperature transmitter

Drain valve

Bypass fordetensioning HU



10µm

3µm 3µm

max

min

M10µm

500µmTT

PT

LS

°C



10µm

3µm 3µm

max

min

M10µm

500µmTT



10µm10µm

3µm 3µm3µm 3µm

max

min

max

min

MM10µm

500µm

10µm

500µmTTTT

PT

LSLS

°C°C

Oil pump

Level switch

Pressure transmitter

Thermostat


4.7 HydroCOM Service Software (HSS) The HSS is used for configuration, analysis and service of following HOERBIGER products: • HydroCOM • HydroCOM-RecipCOM • ROD-Position Analyzer (on-line rider ring wear monitoring) A PC with Microsoft Windows® operation system is required. The system requirements are specified in the HSS user manual.

4.8 Fast-TIM Fast-TIMs (Fast-TIM transmitter interface module) enable decentralized data acquisition and bus communication. Fast-TIMs are designed for connecting fast signals (e.g. indicator pressure, rod drop) and slow signals (e.g. valve nest temperature). Fast-TIMs contain power supply and barriers for intrinsically safe transmitters and are mounted on or next to the compressor frame, reduce field wiring and cut installation costs significantly. Since the Fast-TIMs are installed like the actuators in the field its electronic is mounted in flame-proof housings. The electric connection is identical to the actuator. In addition to the actuator there is an additional connection box for intrinsically safe transmitters:

Piston rod position(rod drop)

Indicator pressure TemperaturePressure

VibrationsFlow

Fig .9.: Possible transmitter connections Fast-TIM

The following types are available Fast-TIM/8C: 8 channels:

All channels for 4-20mA transmitters (slow or fast signals) Fast-TIM/6M 6 channels:

4 channels for 4-20mA transmitters. 2 channels for rod drop transmitters.

Fast-TIM/4R 4 channels: All 4 channels for rod drop transmitters


4.9 Compressor Condition Monitoring (RecipCOM) The optional on-line compressor condition monitoring system (recipCOM), HydroCOM-RecipCOM is specifically designed for reciprocating compressor. HydroCOM-RecipCOM is an on-line RecipCOM-System for monitoring valves, rider rings, piston rings, packings, rod load and rod load reversal, controls, crosshead/piston connection and process parameters. Signals are sampled synchronically by the Fast-TIM and transmitted via HydroCOM bus to the CIU. The CIU receives the digital data and controls data acquisition. The CIU makes the data available to the RecipCOM-PC performing analysis and monitoring. The industrial type RecipCOM-PC can be installed in the HydroCOM control cabinet. Data from your PLC/DCS are integrated via Modbus or OPC. Full network integration enables user access via network (LAN, WAN, Internet) or modem with the HOERBIGER supplied Visu-Software. HydroCOM-RecipCOM’s modular structure provides a variety of functions:

• Process Overviews for a schematic display of the main operating conditions

• HydroCOM Status Monitoring for visualization and logging of HydroCOM status

• Trend Monitor: Signals and calculated parameters are logged for historical and trend analysis

• PV Diagram Analysis of indicated pressure for on-line condition and performance monitoring

• Wear Monitoring: 36 segment analysis of piston rod position and rider ring wear monitoring

• Machine Status: Traffic lights clearly indicate compressor status and alarms

• Integration of process data from PLC/DCS vie MODBUS or optional OPC

• Log Book (alarm list)

• Ring-buffer for dynamic signals (indicator pressure, rod position)

• High resolution ring-buffer for process data


Fig 10.: Examples User Interface HydroCOM-RecipCOM


4.10 Rod-Position Analyser (RPA) The Rod-Position Analyser is an optional on-line monitoring system to monitor rider-ring wear and vertical piston rod run-out. The RPA measures and analyses the position of the piston rod at each degree crank angle and provides following values: Stand-out of rider rings: The RPA is the on-line “feeler gauge” to determine the standout (clearance between piston and liner) during operation. Based on the trend in the DCS, the remaining lifetime of the rider rings can be estimated and the compressor shutdown for their replacement be planned. Run-out: Additionally the RPA works as on-line “dial indicator” to determine the vertical run out during operation. A change in run-out indicates excessive crosshead clearance, alignment problems and a loose connection between piston and crosshead. In addition to the CIU, EPS and TDC-sensor the rod-position probes have to be installed. The probes are fixed to the pressure packing and are wired to the Fast-TIM that is mounted locally at the compressor. The values for stand-out and run-out are transmitted to PLC/DCS with the CIU analog outputs (4..20mA) or Modbus.

Fig 11.: Mounting position RPA probes


5 Installation examples

The following picture shows the typical installation of the HydroCOM system on a double acting, horizontal reciprocating compressor.

Fig 12.: Typical HydroCOM installation

The installation of the HydroCOM system includes the following points:

• Installation of the valves and unloaders • Installation of the Actuators on the suction valve covers • Installation of the Hydraulic Unit • Installation of the CIU, EPS, IA within the safe area (in a cabinet) • Installation of all pipes and hoses • Installation of the wiring • Programming of the DCS (or installation of the ABB external loop

controller if ordered from HOERBIGER) If required HOERBIGER offers turnkey installations.

Wiring and Piping for leakage oil & leakage gas

Actuators

Pipes and hoses for the Hydraulic system

Hydraulic Unit

Documents

HYDROCOM - FOR RECIPCOMPRESSOR