Gas Seal Specification

8/3/2019 Gas Seal Specification

1/31

Dry Gas Seals Manual

PROJECT 560MW Bin Qasim Combined Cycle PowerProject Karachi

EQUIPMENT Natural Gas Compressor( )

MODEL MCL526+MCL457


2/31

DRY GAS SEALS MANUAL

Sichuan Nikki Seals Co., LTD

Aug. 2010

TABLE OF CONTENTS

1 INTRODUCTION... 3

2 STRUCTURE SPECIFICATION....... 7

3 CONTROL SYSTEM.....9

4 INSTALLATION / REMOVAL.....20

5 OPERATION / MAINTENANCE..25

6 SHIPMENT / STORAGE28

Appendix 1 Assembly Drawing CW (LP)

Drawing No: SNS0920-051-00-CW

Appendix 2 Assembly Drawing CCW (LP)

Drawing No: SNS0920-051-00-CCW

Appendix 3 Assembly Drawing CW (HP)

Drawing No: SNS0920-052-00-CW

Appendix 4 Assembly Drawing CCW (HP)

Drawing No: SNS0920-052-00-CCW

Appendix 5: Dry Gas Seal Control System P&ID (LP)

Drawing No: SNS0920-051-XT

Appendix 6: Dry Gas Seal Control System P&ID (HP)

Sichuan Nikki Seals Co., LTD Tel02885369013 Fax02885366222 Home Sitewww.sns-china.com

2


3/31


Drawing No: SNS0920-052-XT

Appendix 7: Installation And Removal Drawing (LP-CW)

Drawing No: SNS0920-051-AZ-00-CW

Appendix 8: Installation And Removal Drawing (LP-CCW)

Drawing No: SNS0920-051-AZ-00-CCW

Appendix 9: Installation And Removal Drawing (HP-CW)

Drawing No: SNS0920-052-AZ-00-CW

Appendix 10: Installation And Removal Drawing (HP-CCW)

Drawing No: SNS0920-052-AZ-00-CCW

Appendix 11: Installation And Removal Instruction (LP-CW)

Drawing No: SNS0920-051-ZC-CW

Appendix 12: Installation And Removal Instruction (LP-CCW)

Drawing No: SNS0920-051-ZC-CCW

Appendix 13: Installation And Removal Instruction (HP-CW)

Drawing No: SNS0920-052-ZC-CW

Appendix 14: Installation And Removal Instruction (HP-CCW)

Drawing No: SNS0920-052-ZC-CCW


3


4/31


1.

INTRODUCTION

Dry Gas Seals is a type of newly developed non-contact shaft seal. Its invention is

based on gas-lubricated-bearing theory since the 60s of last century. After several years of

research and test, John Crane put out the worlds first dry gas seal into industrial use.

A dry gas seal is suitable for any gas-delivering system. By now, it is widely used

on centrifugal compressors in Chinas petrochemical, oil refining, chemical engineering

and pharmacy industry. Results have shown that dry gas seals compare favorably with

ordinary oil seals in many ways. First, it is non-contact and therefore there is hardly any

restriction to its PV value. Second, it is more suitable as shaft seals for high speed, high

pressure or large centrifugal compressors than contact mechanical seals. Third, it does

not need lubricants or lubrication control system; its gas control system is less complicated

than ordinary mechanical seals lubrication system.

Invention of dry gas seal has been a breakthrough in sealing technology. As a

result of the combination of dry gas seal and block sealing theory, a new conception of

gas sealing with no leakage has replaced the traditional fluid sealing.

Comparing with ordinary oil seal, a dry gas seal has many merits:

Economize the extra power spent on driving the system.

Greatly reduced the maintenance expense and shutdown times.

Avoiding the possibility that process gas is polluted by oil

Low leakage of the sealing gas.

Lower maintenance cost, economic and practical is better.

Low power.

Long life and stable performance.

1.1 PRINCIPLES OF DRY GAS SEALS

The main difference between a dry gas seal and a mechanical seal is there are

equally spaced hydrodynamic grooves on one sealing face of dry gas seal. When

operating, gas flows into the grooves and compressed; to form a high-pressure part and


4


5/31


the sealing face begins to work.

Fig.1 shows a typical spiral grooves on the

stationary ring:

The depth of spiral grooves on a sealing face

(Fig.1) is within 8~15m. Both the springs and

the sealed fluid provide static pressure loaded on

the sealing face. It always exists whether the

shaft is rotating or not. When the seal operates,

the sealing gas is pulled into the spiral grooves

by viscous tangential force generated by the

rotating ring. In the grooves, the gas is driven to

move toward the center but blocked by the sealing dam, therefore the gas is compressed

and form a high-pressure zone. The high pressure lead to the sealing faces to open and

there becomes a gas film between the faces. The balance between the opening force by

film and the closing force by spring and medium acting force makes non-contact operating

of the seal possible. Gas film has certain rigidity to ensure stable working of a seal and

lubricant function.

Fig.2 is a force diagram of a spiral groove dry gas seal which shows how the rigidity of the

gas film is formation and how does it guarantee the stable performance of the seal. In

normal conditions, the opening force is equal with the closing force. However, if comes a

disturbance (processing or operating wave) which reduces the thickness of the gas film,

the tangential force will grow and spiral groove of produce kinetic pressure will also grow

to cause the gas film pressure increase , open force will increase and the gas film will

return to normal thickness for keeping force balance. On the contrary, if the disturbance

causes increase thickness of gas film, the tangential force will reduce and spiral groove of

produce kinetic pressure will also reduce to cause the gas film pressure reduce then the

opening force will drop and the gas film will return to normal thickness. Therefore, Dry gas

seal would always return to its working clearance after the disturbance is eliminated in the

scope of design. The rigidity of the gas film (Fv/Tv,Fv: variation of acting force on the

sealing face, Tv: variation of thickness of the gas film) is an index usually used to judge


5

Fig.1 typical spiral grooves


6/31


the stability of a seal. the value bigger is better.

1.2 Seal Type And Monitoring System

For different kinds of working condition, there are various types of seals to choose.

Usually, dry gas seals can be classified as single end face seal, double end face seal,

tandem seals and tandem seals with intermediate labyrinth.

To ensure stable operation of dry gas seal, relative monitor and control system is

provided with the seal system. On one hand, the system provides clean and dry gas to the

seal; on the other hand, it monitoring the seals working condition. Make sure the seal is at

best working condition and give out alarms when the seal fails, our workers can deal with

the problem as soon as possible.

By means of measuring the flow of gas leakage and monitoring relative pressure , we

can see whether the seal is operating normally. The control system gives out alarms when

the flow or pressure value is abnormal (too high or too low). If the gas leakage exceeds

trip value, the seal might have failed and the system will interlock shut down.


6

Fig.2 force diagram of spiral groove dry gas seal


7/31



7


8/31


2.

STRUCTURE SPECIFICATION

This natural gas compressor used on 560MW Bin Qasim Combined Cycle Power

Project Karachi is a multistage compressor manufactured by Shenyang Blower Works

Group Co., Ltd. Model: MCL526 LP +MCL457 HP ; Code: H1191. The

operating condition is as following:

1) LP:

Process Gas: Natural Gas Molecular Weight: 18.6

Suction Pressure: 2.0barg Discharge Pressure: 10.27barg

Suction Temperature: 28oC Discharge Temperature: 158.4 oC

Shaft Speed 9934 rpm MCS

2) HP:

Process Gas: Natural Gas Molecular Weight: 18.6

Suction Pressure: 10.02barg Discharge Pressure: 29barg

Suction Temperature: 45oC Discharge Temperature: 147.9 oC

Shaft Speed 9934 rpm MCS

2.1 Features Of Dry Gas Seal

Reference: APPENDIX 1 , 2 3 4

The GCTL01/L-152 and GCTL01/L-133 gas seals are Tandem Gas Seal with

Labyrinth, which are of high safety and reliability. This structure can ensure that process

gas will not leak into atmosphere, and the injected gas (N2) will not leak into the

compressor.

Tandem Gas Seal is comprised of two single end face seals in a tandem

arrangement. Primary seal bear major pressure difference. Secondary dry gas seal is

an auxiliary safety seal, which usually works under lower pressure difference, and the seal

face operates at a non-contacting state to avoid abrasion. When primary seal failed,

secondary seal can bear major pressure difference to ensure the compressor be shut

down safely, and excessive leakage gas can be avoided by secondary seal. The barrier


8


9/31


seal on the atmospheric side can prevent lubricant oil enter to the sealing area and

provide a clean and dry operation environment.

Because of slight abrasion during start-up/shut-down process, the rotating ring is

made of Tungsten Carbide with high rigidity, while the stationary ring is made of Carbon

with self-lubricating. The rotating ring has a series of spiral grooves on its running faces,

when rotation, high rigidity gas film is formed in between the rotating and static ring. Open

force and close force dynamic balance. Make seal face separate 3 ~ 5 u m, realize the

non-contact state.

The dry gas seal is assembled structure to prevent any damage by transport. Meanwhile,

the setting plates should not be taken off until the seal is installed onto the device with an

installation tool. axial installing precision and avoids outside dust and impurity affecting the

performance of the seal.

2.2 Performance Criteria

Expected value of the seal under normal condition (1 suit):

1) LP

Leakage rate of processing gas: less than 2 Nm3

hConsumption rate of secondary seal gas(N2): less than 16 Nm3 h

Consumption rate of barrier gas (N2): less than 40 Nm3 h

Power: less than 3kw

2) HP

Leakage rate of processing gas: less than 4 Nm3 h

Consumption rate of secondary seal gas(N2): less than 16 Nm3 h

Consumption rate of barrier gas (N2): less than 40 Nm3 h

Power: less than 3kw

3. CONTROL SYSTEM

3.1. General


9


10/31


Special monitoring and controlling system is designed for the seal (SEE

APPENDIX five and six). The purpose of the system is to provide clean and dry gas for the

seal, and to monitor the working condition of the seal. The working process of the system

is:

When the seal is normally operating, cooled and dehumidified process gas from

discharge side works as primary seal gas .The gas is introduced into the seal chamber

by filter and diff pressure control valve according to setting pressure (the pressure

difference for primary seal gas and process gas at secondary balance pipe more than

1.5bar), Its pressure must be controlled at 3bar higher than the process gas at the balance

pipe, to prevent unclean process gas entering the sealing area and this value is measure

by a differential pressure transmitter and transmitted to the control room DCS/ITCC.

The majority of primary seal gas introduced into the seal chamber goes back into the

casing by labyrinth sealing at the end of the shaft. Only a few of the seal gas (less than

2Nm3/h/ per set) may leak through the sealing faces of the main seal. The leakage mixed

with secondary seal gas (nitrogen), as the primary seal gas leakage, primary seal gas

leakage piped go back to controlling panels to measure its pressure and flow and then

vented .

The secondary seal work as assistant seal. Though this seal did not bear the main

pressure, there becomes a stable gas film between the faces, which based on proper

pressure. The piped Nitrogen is separated into two lines after filtered and decompressed,

one line gas as secondary seal gas, goes through a flow control orifice and throttle valve

before entering the seal chamber. Themajority of this line gas after going though middle

labyrinth is mixed with leakage from the primary seal face and then vented, only a little of

this line gas will leak from the secondary seal face and this little gas is mixed with part

barrier gas which leaks from process side of labyrinth, the mixed gas is secondary seal

gas leakage, the leakage is vented though pipe.

The other line of nitrogen, work as barrier gas, is led into the labyrinth seal after

controlled by flow control orifice and throttle valve. One part of the gas is discharged into

bearing case through the labyrinth seal, The other part, mixed with the leakage form

secondary seal faces as the secondary seal gas leakage, will be vent. Start the barrier gas


10


11/31


before starting the lube system. Its pressure should be maintained at 0.03MPa to form a

reliable blocking seal and to prevent the lubricant steam from entering the dry gas seal

faces.

The primary seal gas leakage flow is used to judge whether the seal is working

normally. Its value is measured by flow meter and transmitted to the control room.

However, if primary seals fails, primary leakage flow and pressure will increase quickly , if

secondary seals fails, primary leakage flow and pressure will decrease quickly and when it

reaches the set value will send alarm and trip.

3.1.1

LP Control System of the Seal

1) Primary seal Gas

When the seal is normally operating, dehumidified process gas from filter

discharge side is introduced into the dry seal system .The process gas, work as primary

seal Gas, is divided into two lines after going through V1, V2, V5, FL1, FL2 FL3 FL4

standby , V6,V10,YAEKD91ZZ001 and V11. One line goes into the seal chamber of

the suction side (non-drive end) through V13 YAEKD91CF501 V14. The other linegoes into the seal chamber of the discharge side (drive end) through

V16 YAEKD91CF502 V17.

The control signal of diff pressure control valve YAEKD91 ZZ001 is

measured by diff pressure transmitter and transmitted to the DCS/ITCC and then

output to diff pressure control valve. Therefore the pressure after control valve is

controlled at 3 bar higher than the process gas at the secondary balance pipe. At

the same time the flow which enters into YAEKD91CF501 YAEKD91CF502 is

controlled at 40 Nm3/h by adjusting V13 V16 by hand.

2) Secondary Seal Gas

Nitrogen about 6barg work as secondary seal gas, its pressure is

decompressed to 0.7barg and then separated into two lines after going through V19, V20,

FL5, ( FL6 as a standby) ,V21,V24,OR1. One line goes into the secondary seal chamber

of the suction side through V27 YAEKD91CF503 V28 V30. Another line goes


11


12/31


into the secondary seal chamber of the discharge side through

V31 YAEKD91CF504 V32 V34.

3) Barrier Gas

Nitrogen after filter, work as barrier gas, is separated into two lines. The pressure

of one line Barrier Gas is decompressed to 0.3barg after going through V35 OR2 .This

line of piped Nitrogen goes into the barrier seal chamber of the suction side (non-drive

end) through V36 V38. The pressure of another line Barrier Gas is decompressed to

0.3barg after going through V39 OR3 .This line of piped Nitrogen goes into barrier seal

chamber of the discharge side (drive end) through V40 V42.

Attention: Start the barrier gas before starting the lubricant system. And shut

down the barrier gas after the lubricant system is stopped ten minutes!

4) Drive gas

Diff pressure control valve YAEKD91ZZ001 use filtered Instrument air as power

supply.

5) Primary seal leakage gas

The primary seal leakage gas of suction side (non-drive end) is vented after going

through V43 V44 YAEKD91CF001 V45 V47. The primary seal leakage gas ofdischarge side (drive end) is vented after going through V48 V49 YAEKD91

CF002 V50 V52

6) Secondary seal leakage gas

The component of secondary seal leakage gas is nitrogen. The secondary seal

leakage gas will be vented to safety zone though flange pipe joint. (One line goes though

flange D2 at suction side (non-drive end), another line goes though flange D1 at discharge

side (drive end).

7) Drain

In order to prevent large oil drops from entering the dry gas seal area and polluting

the gas seal when the compressor is at commissioning oil cycle or oil pressure

undulate, the drain should be open. When the compressor is normally operating, the drain

should be closedown, but need check it at regular intervals.

Nitrogen for compressor staring


12


13/31


The pressure of discharge side do not rise to normal condition at the moment of

compressor staring, so the pressure difference between suction side and discharge side is

very low and the primary seal gas may can not introduce into seal chamber. Therefore we

use nitrogen to replace process gas from discharge side to work as primary seal gas. The

pressure of nitrogen is controlled at 0.2MPaG higher than casing inside.

3.1.2

HP Control System of the Seal

1) Primary seal Gas

When the seal is normally operating, dehumidified process gas from HP discharge

side is introduced into the seal system .The process gas, work as primary seal Gas, is

divided into two lines after going through V1, V2, V5, FL1, FL2 FL3 FL4 as a

standby , V6,V53,YAEKD91ZZ002 and V54. One line goes into the seal chamber of

the suction side (non-drive end) through V56 YAEKD91CF505 V57. The other line

goes into the seal chamber of the discharge side (drive end) through

V59 YAEKD91CF506 V60.

The control signal of diff pressure control valve YAEKD91 ZZ002 ismeasured by diff pressure transmitter and transmitted to the PLC and then output

to diff pressure control valve. Therefore the pressure after control valve is

controlled at 3 bar higher than the process gas at the secondary balance pipe. At

the same time the flow which enter into YAEKD91CF501, YAEKD91CF505 is

controlled at 40 Nm3/h by adjusting V59 V59 by hand.

2) Secondary Seal Gas

Nitrogen about 6barg work as secondary seal gas, after going through V19, V20,

FL5, ( FL6 as a standby) ,V21,V62,OR4, its pressure is decompressed to 0.7barg and

then separated into two lines. One line goes into the secondary seal chamber of the

suction side through V65 YAEKD91CF507 V66 V68 . Another line goes into

secondary seal chamber of the discharge side through

V69 YAEKD91CF508 V70 V72.

3) Barrier Gas


13


14/31


Nitrogen after filtered work as barrier gas is separated into two lines. The pressure

of one line Barrier Gas is decompressed to 0.3barg after going through V73 OR5 .This

line of piped Nitrogen goes into the barrier seal chamber of the suction side (non-drive

end) through V74 V76. The pressure of another line Barrier Gas is decompressed to

0.3barg after going through V77 OR6 .This line of Nitrogen goes into the barrier seal

chamber of the discharge side (drive end) through V78 V80.

Attention: Start the barrier gas before starting the lubricant system. And shut

down the barrier gas after the lubricant system is stopped ten minutes!

4) Drive gas

Diff pressure control valve YAEKD91ZZ002 use filtered Instrument air as power

supply.

5) Primary seal leakage gas

The primary seal leakage gas at suction side (non-drive end) is vented after going

through V81 V82 YAEKD91CF003 V83 V85. The primary seal leakage gas at

discharge side (drive end) is vented after going through V86 V87 YAEKD91

CF004 V88 V90

6) Secondary seal leakage gas

The component of secondary seal gas leakage is nitrogen. The secondary seal

leakage gas will be vented to safety area though flange pipe joint. (One line goes though

flange D4 at suction side (non-drive end), another line goes though flange D3 at discharge

side (drive end).

7) Drain

In order to prevent large oil drops from entering the dry gas seal area and polluting

the gas seal when the compressor is at commissioning oil cycle or oil pressure

undulate, the drain should be open. When the compressor is normally operating, the drain

should be close, but need check it at regular intervals

Nitrogen for compressor staring

The pressure of discharge side do not rise to normal condition at the moment of

compressor staring-up, so the pressure difference between suction side and discharge

side is very low and the primary seal gas may can not be introduced into seal chamber.


14


15/31


Therefore we use nitrogen to replace process gas from discharge side to work as primary

seal gas. The pressure of nitrogen is controlled at 0.2MPaG higher than pressure of

casing inner.

3.2. Measuring, Alarm And Interlock

3.1.2

LP Casing

1) The pressure difference for primary seal gas and process gas at the

secondary balance pipe

Diff pressure transmitter YAEKD91CP052 is to measure thepressure difference for

primary seal gas and process gas at the secondary balance pipe. The normal value is

N=3bar. Low PD alarm is given at L=1bar. The pressure difference higher than 1.5bar is a

precondition for the compressor startup.

2) Filter Blockage

Diff pressure transmitter YAEKD91CP051 is to measure the pressure difference on

the two sides of the primary seal gas filter. High-pressure alarm is 0.08MPa. Diff pressure

transmitter YAEKD91CP053 is to measure the pressure difference on the two sides of

nitrogen filter. High-pressure alarm is 0.08MPa.

condensate of primary seal gas filter FL1 FL2 FL3 FL4 is controlled by

valve V9 and discharge to container though flange N3 at regular intervals.

The nitrogen filters FL5, FL6 discharge condensate automatically by floating balls.

3) Pressure of Barrier Gas

Pressure transmitter YAEKD91CP001 is to measure the pressure of barrier gas.

The normal value is 6bar. Low pressure alarm is 3.5bar. The pressure higher than 4.5bar

is a precondition for the lube oil pump startup.

4) Pressure of Primary seal leakage gas

Pressure transmitter YAEKD91CP002 YAEKD91CP003 are to measure the

Pressure of Primary seal leakage gas on both the suction side (non-drive end) and the


15


16/31


discharge side (drive end). The normal value is 0.6bar. High pressure alarm is 1bar. HH

pressure alarm is 2bar.

5) Flowrate of Primary seal leakage gas

Metallic float flow meter YAEKD91CF001 YAEKD91CF002 are used to

measure the Flowrate of Primary seal leakage gas on both the suction side (non-drive

end) and the discharge side (drive end). The normal value is 8.5Nm3/h, High flowrate

alarm is 17Nm3/h. Low flowrate alarm is 4Nm3/h.HH flowrate alarm is 34Nm3/h.

3.2.2 HP Casing

1) The pressure difference for primary seal gas and process gas at the

secondary balance pipe

Diff pressure transmitter YAEKD91CP054 is to measure thepressure difference for

primary seal gas and process gas at the balance pipe. The normal value is 3bar. Low PD

alarm is 1bar. The pressure difference higher than 1.5bar is a precondition for the lube oil

pump startup.

2) Pressure of Primary seal gas leakage

Pressure transmitter YAEKD91CP004 YAEKD91CP005 are to measure the

Pressure of Primary seal gas leakage on both the suction side (non-drive end) and the

discharge side (drive end). The normal value is 0.6bar. High pressure alarm is 1bar. HH

pressure alarm is 2 bar.

3) Flowrate of Primary seal leakage gas

Metallic float flowmeter YAEKD91CF003 YAEKD91CF004 are used to measure

the Flowrate of Primary seal gas leakage on both the suction side (non-drive end) and the

discharge side (drive end). The normal value is 6Nm3/h, High flowrate alarm is 12Nm3/h.

Low flowrate alarm is given at L=3Nm3/h.HH flowrate alarm is 24Nm3/h.

3.3. Instructions For Operating the Control System

There are two lines work as Primary seal gas: one line is dehumidified process gas

from NG station filter outlet; another line is Nitrogen for compressor start-up. Low pressure

nitrogen is used as gas source for Secondary seal gas and Barrier Gas.


16


17/31


3.3.1

Seal Control System

1) Open valve

V5 V6 V10 V11 V13 V14 V15 V16 V17 V18 V20 V21

V24 V25 V27 V28 V29 V31 V32 V33 V35 V36

V39 V40 V44 V45 V46 V49 V50 V51 V53 V54 V56

V57 V58 V59 V60 V61 V62 V63 V65 V66 V67 V69 V70

V71 V73 V74 V77 V78 V82 V83 V84 V87 V88 V89 and

all the valves of the instrument and all the three-valve group (close the balance-valve

between the high pressure end and the low pressure end).

Attention: Adjust the valve V43 V48 V81 V86 in according to

the condition of system operation. The flowrate of

YAEKD91CF501 YAEKD91CF502 on two side of LPis controlled at 40 Nm3/h by

adjusting V13 V16 by hand. The flowrate of

YAEKD91CF505 YAEKD91CF506 on two side of HPis controlled at 90 Nm3/h by

adjusting V56 V59 by hand.

2) Close valve

V1 V3 V19 V7 V8 V12 V22 V23 V26 V37 V41

V55 V64 V75 V79.

3) Power on all the pressure and pressure difference transmitters, pressure

switches and flowrate transmitters.

4) Verify if all the stages above is finished and open valves V1, V3 supply gas to

the system. If no abnormal situation occurs after two minutes later, close

V46 V51 V84 V89 and flowrate transmitters

YAEKD91CF001 YAEKD91CF002 YAEKD91CF003 YAEKD91CF004 will start

to work. Check the readings of the flowrate transmitters, if the flowrate exceeds 0.5Nm 3/h,

the seal might have problems in static sealing,analyze reason, until the problem solving.

5) If there is no problems in static sealing , close V15 V18 V58 V61

and flowmeters YAEKD91CF501 YAEKD91CF502 YAEKD91CF505 YAEKD91

CF506 will start to work. Now open V19 and close V29 V33 V67 V71 the


17


18/31


flowmeters YAEKD91CF503 YAEKD91CF504 YAEKD91CF507 YAEKD91

CF50 will start to work. If the readings of the pressure difference transmitter

YAEKD91CP052 YAEKD91CP054 higher than 1.5 bar and the readings of pressure

transmitter YAEKD91CP001 higher than 4.5bar,adjusting V13 V16 by hand to make

sure The flowrate of YAEKD91CF501 YAEKD91CF502 on two side of LP is controlled

at 40 Nm3/h and adjusting V56 V59 by hand to make sure The flowrate of

YAEKD91CF505 YAEKD91CF506 on two side of HP is controlled at 90 Nm3/h, at now

the compressor is allowed to start-up, but must make sure the speed be no less than

1000rpm. This period of testing time should be as short as possible. If the compressor is

running normally, flowrates and pressure values will remain stable. However, if any value

reads high or even alarms occur, it is necessary to checking position of all the valves and

readings of all instrument to analyzing the problem.

6) If the readings of pressure difference transmitter for filter YAEKD91 CP051 or

YAEKD91 is at the high alarm H=0.8barg, slowly open valve V7, V8 or V22 V23 and

close valve V5, V6 or V20,V21. changeover to filters FL3, FL4 or FL6 and change the

original filter element.

Attention: Primary seal gas filters (FL1, FL2, FL3, and FL4) discharge

condensate by hand, should check them periodically. Discharge condensate need

changeover to standby condition. The nitrogen filters (FL5, FL6) are floating values

(discharge condensate automatically by floating balls).

3.4. On Site Piping & Tubing

1)

Material for newly connected pipes and tubes should be stainless steel.

2)

Polish all the trimmed edges before welding and inject argon into the pipes and tubes

to work as a protection. Argon-arc welding should be adopted.

3)

Check if condensate drain valves are needed on pipelines connected to sharing

utilities. Meanwhile, for convenient operating and monitoring, isolating valves and pressure


18


19/31


gauges should be added to the near spot of the control system.

4)

Newly added pipelines should be disassembled without interference to each other or

the original pipelines.

5)

After all the pipelines are arranged, acid-wash the pipes and then sweep them with

high-pressure steam before air-drying. Use white clean cloth to wipe the inside of the

pipes and make sure there is no smear or stain on the cloth.

6) The newly arranged pipes should be wash and blown separately before

connect them to the flanges and onto the system.

7) The sweeping air should be clean and dry (pressure no less than 0.5MPa)

and its cleanliness no less than 10m. Time length of the sweeping should be no less than

1 hour.

8)

Put a clean white cloth or linen (silk) at one end of the pipe and sweep the pipe with

air. See if there is any dust or dirt on the cloth.

9)

After pipe arrangement, it is recommended to do pressure test and flaw detection to

the high-pressure pipelines.

Attention: Before connecting all the pipes, make sure to take off the blind

plates on the flanges. Gaskets are needed between flanges. Check if all the

pipes are correctly connected according to the LIST OF CONNECTIONS OF

SEALING FLANGES and CONECTION LIST from the compressor manufacturer.


19


20/31



20


21/31


4.

INSTALLATION / REMOVAL

Dry gas seal is a precision part. Any incorrect installation or removal operation could

cause damage to the seal or affect longevity. It is recommended that the seals should

be fitted by a Sichuan Nikki trained engineer or certified designee when first

installing.

The seal is comprised of seal cartridge and separation seal. It is in cartridge

assembled, with setting plates to connect the rotating part and the stationary part. It does

not need to be dissembled before installation. Use installation kit to put the seal into seal

chamber from end of the shaft and remove the setting plates. The whole process is

convenient and precise.

Attention: It is recommended that site installation of the seal be arranged after

load-less test of the compressor, when there is no assembly or mechanical problem

of the compressor. Meanwhile, the seal gas supply flow must be sufficient enough

during air tightness test and other tests.

4.1 Exercising the seal

Exercising the seal helps to eliminate possible sticking of the dynamic o-ring due to

long periods of storage.See Assembly Drawing (APPENDIX 1, 2 3 4)

4.1.1 Rotating Examination

1) Place the seal cartridge on a clean, flat table with the setting plates facing

down. Remove the socket head cap screws and the shipping plate.

2) Turn over the seal cartridge with the setting plates facing up. Support the

retainer inner so that the rotor is off the tabletop.

3) Remove the setting plates.

4) Lightly rotate the sleeve in the direction marked on rotor. If the seal moves

freely, it is qualified. If not, there might be steam or oil in the sealing faces. Professional


21


22/31


engineer is needed to clean the seal.

4.1.2 Floatability Examination

1)

Slowly turn over the seal cartridge again. Support the retainer outer so that the

rotor is off the tabletop.

2)

Grasp the sleeve and evenly press on the top until it can no longer be pressed

down. The springs are compressed at the stage.

3)

Slowly release and repeat 4 or 5 consecutive times. If the seal rotor returns to its

original position rapidly, the seal is qualified. If no, the seal must be dissembled to further

check.

4)

After examination, fit the setting plates again.

4.2 Compressor Preparation

1) Check if all the pipes are connected. Sweep the pipes related to the dry gas

seal (especially pipes at the gas inlets to the seal) to prevent dusts or welding slag from

getting into the seal chamber.

2)

Clean the entire area into which the seal fits. No dust, rust or greasy dirt is

allowed.

3)

Make sure that all the lead edges on bore and shaft over which the seal passes

have the required chamfers. No scratch, burr or other flaws is allowed. Rectify as

necessary.

4)

Carefully check the o-rings at outer surface of the seal and inside of the sleeve.


22


23/31


Replace any flawed or damaged parts

5)

Axial location of shaft: During the installation process, the shaft must be fixed in its

axial operating position. Measure to verify the axial position of the shaft to compressor

casing. Adjust the adjusting ring when needed. It is recommended that the thrust end gas

seal be installed first. The other seal is installed after installation of the thrust collar.

6)

Radical location of shaft: The bearing bush must be removed when installing or

removing the seal, and that might cause eccentricity of the shaft and the seal housing.

Therefore, the shaft must be lifted and centered in the seal housing by special tools during

the installation process.

7)

Verify the installation dimension as shown on the drawing. Press the shaft to its

working position.

8)

Check whether the direction marked on the seal casing is in accordance with the

shaft rotation of the compressor.

9)

Without removing them from their grooves, lightly lubricate 0-rings with silicon

grease (not other grease or lubricant). Wipe off excessive grease, or it might get into the

sealing area.

4.3 Installation

ATTENTION: In the process of installation, take off the radical bearing bush and

fix the axial and radical position of the rotator according to the case. Please refer to

the INSTALLATION AND REMOVAL DRAWING (APPENDIX 7-10) and INSTALLATION

AND REMOVAL INSTRUCTION (APPENDIX 11-14).

1) Fix the shaft in its radical operating position.

2) Install the adjusting ring first.


23


24/31


3) Place the seal cartridge onto the shaft. Avoid any bruise or dust getting into

the shaft sleeve. Push the seal onto the shaft sleeve shoulder.

ATTENTION: While pushing the seal cartridge, avoid impact or collision

between the shaft sleeve and the shaft. Especially avoid the O-ring from contacting

the thread on the shaft. It may cause damage to the O-ring. Dust is not allowed to

fall into the inner surface of the shaft sleeve, for it might scratch the shaft sleeve

when installing.

4) Connect the installation plates and screws to the setting plate Outer

(APPENDIX 11-14), and then raise the rotator and make sure it remains at the center

position. When installing, the shaft should always be kept at the axial center. Rotate the

nuts on the screws to push the cartridge SLOWLY and SQUARELY into the compressor.

When rotating the nuts, it is necessary to apply even force on both sides, or scratches on

the seal casing and the seal may occur.

5) Remove the installation plates and screws, and remove the Inner/ Outer

setting plates on the seal cartridge.

6) Rotate the locknut onto the thread of the rotator and Pre-tightening torque

should be maintained at 400N.M. Apply lock jam to the thread.

7) Lightly lubricate outside 0-rings with silicon grease, and then put the

Labyrinth components into the seal casing. Make sure the radical operating position to

ensure socket head cap screws fit the Labyrinth. Dont forget washers.

8) Install split ring, and tighten socket head cap screws. Apply lock jam to the

thread.

9) Check the installation dimensions of the seal again. End if the dimensions are

correct.

10) Repeat the steps above to install the seal on the other side.

4.4 Removal

1) Remove split ring, then remove Labyrinth components by screws. Remove

locknut.


24


25/31


2) Install the Inner/ Outer setting plates on the seal cartridge.

3) Connect the installation plates and screws to the setting plate Outer.

4) Make sure the shaft remains at the center position. Rotate the nuts on the

screws to pull the cartridge SLOWLY and SQUARELY out of the compressor. When

rotating the nuts, it is necessary to apply even force on both sides, or scratches on the

seal casing and the seal may occur.

5) Remove the seal cartridge from the compressor.

4.5 Notes

1)

The customer is not recommended to disassemble the seal because of the seals

high requirements for complicated assembling, cleanliness, precision, and installation

tools.

2) Inner/Outer setting plates are needed for transportation, installation and

disassembling of the seal. After installation, the plates should be put into careful storage.

Without the locating plates, the disassembly would not proceed successfully. If the seal

needs to be return to the Sichuan Nikki Seals Co., Ltd, please put on the locating plates or

damage might occur to the seal.

3)

After installation, please put the installation tools and the packing box into careful

storage.

4) Dry gas seal has high requirements for relative positions between the seal

casing and the shaft. Check the installation dimensions before running the machine. Add

an adjusting ring gasket if necessary.

5)

Maintain the coaxially between the rotator and the seal case and fix the rotator.

6)

Usually, the side with a thrust collar is installed first to guarantee the precise

installation of the seal on the other side.


25


26/31


7)

Thoroughly clean the seal chamber and all the inlet/outlet pipelines.

8)

Use silicone grease for lubrication and no other grease are permitted.

9) After the seal is installed and the setting plate is taken off, the displacement

allowed for the rotator should be no more than 2.5mm.


26


27/31


5.

OPERATION / MAINTENANCE

5.1 Starting Process of the Seal

1) Put into Rules

Start up: First put into the seals control system, then the lube oil system. Note:

that in the seals control system, the primary seal gas should be put into firstly, following

the secondary seal gas and then the barrier gas.

Oil cycle: If there isnt pressure in the shell , the primary seal gas and the

secondary seal gas could be closed and only the barrier gas is needed.

Shut Down: Shut down the lube oil system firstly. If there is return oil, close the

barrier gas, following the secondary seal gas, and at last the primary seal gas. If there is

pressure in the shell, the primary seal gas and the secondary seal gas should not be cut

off until it isnt pressure.

2) Close the discharge valve of compressor, put into the primary seal gas firstly

and close the secondary seal gas to do static test on the primary seal. Meanwhile, the

flowrate transmitters

YAEKD91CF001 YAEKD91CF002 YAEKD91CF003 YAEKD91CF004 should

read 0. If the flowrate is higher than 0.5Nm3/h, analysis reason

3) Make sure the pressure of barrier gas is maintained at higher than

4.5bar.check the pressure of YAEKD91CP506 YAEKD91CP507 YAEKD91

CP510 YAEKD91CP511 is 0.3bar. Adjust orifice bypass valves

V37 V41 V75 V79 until the pressure returns to normal value if there is any

deviation.

4) After passed the static test, put into the systems following step 1.1. Check the

instruments readings at each point. If they are normal. the seal system are ready to work.

5) Start the lube oil system according to the operating instructions.

6) Start the compressor according to the operating instructions. the leakage rate

will increase until the compressor reaches stable state. Note : that the speed of the

compressor should be no less than 1000rpm.


27


28/31


5.2 Note for Start-up

1) Because of tandem dry gas seal, the compressor in the shell must have

pressure. the pressure dont less than 2bar.

2) If the compressor is shut down. start-up again, drain of gas pipes (nitrogen

and process gas) firstly and make sure there isnt condensate before starting the seals

control system. the condensate might get into the sealing faces and cause damage to the

seal.

5.3 Regular Maintenance

Dry gas seal is designed for wide range of services and usually it does not need to be

maintained. Check the primary seal gas leakage flowrate everyday. If it tends to grow, it is

possible the seal is failing. Notice the followings:

1) The seal is forbidden to running in an opposite direction. Avoiding long time

operation under low speed operation.

2) Ensure stable flowrate and pressure of the primary seal gas. Stable and

continuous primary seal gas is the basic requirement for the normal operation of the dry

gas seal.

3) Monitoring the primary seal gas leakage rate. Primary seal gas leakageaffect

the working condition of dry gas seal. There are various reason affect the leakage rate, for

example: process gas undulate, pressure, temperature, speed, etc. Temporary rise of

leakage does not mean failure of the seal. However, if the leakage rises continuously, it is

possible the seal might fail.

4) If the pressure difference of filter reaches alarm value, it is necessary to

changeover the filter. Please check the condensate drain at regular intervals.

5) The condensate drain should be open when the compressor is at normal

running or oil cycle, to prevent oil pressure variation or other fault lead to lube oil through

the barrier seal into the sealing area.

6) Shut down the dry gas seal system at least 10 minutes after totally shutdown


28


29/31


of the compressor and lubricant system.


29


30/31


6.

SHIPMENT / STORAGE

The whole cartridge of seal should be placed in a customized firm box and set up

by foamed plastic. Other spare parts should be packed and put into the inner space of the

shaft sleeve to avoid damage.

Another function for setting plate is to prevent relevant movement between the

stationary parts and the rotary parts and their collision with each other. Therefore, special

setting plates are designed for the whole cartridge of seal for its transportation and

storage. Protecting hood is placed on the fluid side to keep away dust and to protect the

rotary ring.

It is recommended the ambient temperature for storing the seal be 15~25 and

avoid heat sources like boiler, heat exchanger or direct sunshine. Ambient humidity should

be below 75% and desiccant is needed for transportation. Note: Do not use greasy cloth or

paper as waterproof package. If it is for long-term storage, use elastic PE gaskets to seal

the box.

If the seal is placed inside a shutdown compressor for more than 60 days, it is

possible that grease or steam might get into the sealing faces. Check if there is oil inside

the separation gas inlet pipeline. Or, rotate the shaft by hand to see if it moves smoothly.

Only trained specialists are allowed to disassemble the seal and perform cleaning

operation.

The customer is not recommended to uninstall the seal because of the seals high

requirements for complicated assembling, cleanliness, precision, and installation tools.

If the compressors been shutdown for a long time with the seals inside, it is

necessary to fix the shaft to prevent the seal from possible damage. After verify that the

inside of the shell is dry, seal all the connection points on the compressor. Oil residue is

not allowed to contact the seal.

After designed period, parts like elastomers, springs and tension spring need to be

examined. Please send the whole cartridge back to the vendor. Service life of dry gas

depends on the time of storage, working and working condition. In better occasion, the


30


31/31


seal could work continuously for 3 years. However, frequent start-shut operation, vibration,

excessive axial slinger; unclean pipelines could all be reasons for short service life of dry

gas seal.

31

Documents

Gas Seal Specification