Boost Compressor

SOLAR GAS BOOST COMPRESSOR OUTLINE † † † † † † †

Pengenalan Centrifugal Gas Compressor Prinsip Kerja Gas Compressor Compressor Component dan Fungsinya Staging Selection Performance Evaluation Compressor Cleaning / Stripdown Restage

Pengenalan Centrifugal Gas Compressor Centrifugal Gas Compressor adalah salah satu Compressor yang termudah yang ada untuk menaikan tekanan dari gas dengan aliran kontinyu. Solar Compressor Family - C-160 - C-284 - C-306 - C-338 - C-505

Prinsip Kerja Gas Boost Compressor Prinsip Kerja Centrifugal Gas Compressor adalah mengubah energy kecepatan dari gas menjadi energy tekanan dan Fungsinya untuk menaikan tekanan dari gas untuk keperluan tertentu.

Gas Flow Through Impeller

Compressor Stage Component

Compressor Component dan Fungsinya Ø Ø Ø Ø Ø

Casing & End Cap. Rotor Stator Bearing Seal

Housing & End Cap Sebagai manifold / penampungan gas inlet (suction cavity) dan gas outlet (discharge cavity) yang designnya pressurenya disesuaikan dengan Kondisi operasinya / operating point.

Housing & End Cap Gas Compressor C-304

Stator Merupakan bagian yang diam / stationary yang terdiri dari : - Guide Vane - Diffuser.

Guide Vane berfungsi sebagai pengarah dari aliran untuk menuju ke impeller. Diffuser berfungsi untuk mengubah energy mekanik / gerak dalam hal ini kinetik energy menjadi energy tekanan / pressure.

Rotor Merupakan susunan dari beberapa buah impeller yang stagingnya telah di

sesuaikan dengan kebutuhan operasinya dan berfungsi untuk mempercepat aliran gas sebelum memasuki diffuser daipada stator

Rotor

Pin

Center Stud

Bearing Berfungsi untuk meredam getaran yang ditimbulkan oleh compressor dan type yang digunakan kebanyakan adalah Hydrodynamic journal bearing yang lazim kita sebut sebagai tilt pad bearing Alasan kenapa memilih Tilt pad bearing - Effekivitas untuk meredam getaran sangat tinggi - Meniadakan oil whirl / oil whip - Life timenya relative lama

Tilting Pad Bearing

Thrust Bearing • Berfungsi untuk menahan gaya axial • Ada dua macam type – Tilt pad thrust bearing – Non Tilt pad thrust bearing

• Ada yang dilengkapi dengan sensor, untuk memonitor thrust bearing temperature

Tilt Pad Thrust Bearing Pad

Temperature sensor

Seals Seal System terdiri : - Labyrinth : Bentuknya sekat-sekat yang tiap ujungnya berbertuk runcing / tajam dan berada dikedua sisi impeller atau stub shaft dan berfungsi untuk meminimize / mengurangi kebocoran gas diantara tiap-tiap stage didalam compressor . - Buffer Gas / Seal Gas Berfungsi untuk menjaga agar seal oil / lubrikasi tidak masuk kedalam compressor / process - Seal Oil Berfungsi untuk menjaga agar process gas tidak masuk kedalam system pelumasan / lubrikasi.

Labyrinth Seal (1) Stationary Housing Kondisi Seal sebelum beroperasi Rotating Shaft

Gas Flow

Soft Babbit Replaceable liner Kondisi Seal sesudah beroperasi

Labyrinth Seal (2)

Labyrinth Seal

Seal Oil dan Buffer Gas Sistem Fungsi : “Sebagai sealing antara sistem oil dan sistem gas” 9 Seal Oil : Mencegah masuknya gas ke sistem oil 9 Buffer Gas : Mencegah masuknya seal oil ke compressor casing

Seal Oil & Seal Buffer Gas

Seal Oil & Seal Buffer Gas (cont,d)

Buffer Gas DP

Seal Oil & Seal Buffer Gas (cont,d) Buffer Gas Seal P = 55 psig Lubricating Oil

Balance Piston Seal (Discharge)

P = P-suct + 20 psi

P = P-suct + 15 psi

Seal Oil

Buffer Gas

P-suct / P-disch Gas dalam Compressor Discharge Suction

Seal Oil dan Buffer Gas Drain

Komponen Seal oil System • Auxiliary Seal Oil Pump – Start saat tekanan prelube > 6 psig – Berhenti saat loading speed (90% NGP) – Saat engine Shutdown, Start pada saat 90% , berhenti Pcasing < 4 psig

NGP <

S-21

Komponen Seal oil System (1) Main Seal Oil Pump Mengambil alih Auxiliary Seal Oil Pump pada NGP > 90% 2000 rpm pada 100% NGP

Flow Regulator Menjaga aliran seal oil konstan pada setiap tekanan

Komponen Seal oil System (2) Differential Pressure Regulator Seal Oil DP Regulator Menjaga tekanan seal oil 20 psid di atas tekanan suction

Buffer Gas DP Regulator Menjaga tekanan buffer gas 15 psid di atas tekanan suction

Tekanan acuan : Tekanan Suction atau Drain Cavity ( Seal Oil dan Buffer Gas Out )

Komponen Seal oil System (3) Seal Oil DP Regulator Diaphragm

Seal Oil IN

Seal Oil Return

Buffer Gas

Maximum Seal Oil Leakage

Komponen Seal oil System (3) Seal Oil Separator / Trap Memisahkan gas dari seal oil agar tidak masuk ke Lube Oil Tank Meyakinkan seal oil tidak tertarik ke pipeline melalui booster compressor Seal Oil kembali ke tank dibantu oleh tekanan gas di atasnya

High Pressure Oil Trap

Type Seal Oil Trap Seal Oil & Gas Mixed

Gas out Floater

Oil return port Spring

Oil out

Sistem Buffer Gas 9Internal Gas dari Balance Piston labyrinth seal (discharge) diregulasi tekananya, diinjeksikan sebagian ke suction bearing capsule

9Eksternal Gas dari discharge elbow diregulasi tekanannya, diinjeksikan ke suction dan discharge bearing capsule

Sistem Buffer Gas-Internal

To Suction pipe

BG Reg.

To Suction Brg. Capsule

Sistem Buffer Gas-External

External Buffer Gas sources

BG Reg

Buffer Gas DP Operating Range Model No.

Buffer Gas DP (psig) Minimum

Nominal

Maximum

C-16

5

15

50

C-16H

5

15

50

C-160

5

15

50

C-28

5

15

50

C-30

5

15

50

Dry Seal System In this system, separation of lube oil and process gas is accomplished by a series of seals, installed between the inboard journal bearing and the impeller.

Buffer Gas • • • • •

Buffer gas is injected between the primary seal and the labyrinth seal on the rotor hub, at pressure above suction pressure. The differential pressure and proportional flow path sizes causes most of the buffer gas flows across labyrinth seal and back to suction chamber of the compressor. The remaining small amount of buffer gas flows across primary seal and is vented from the seal assembly through a fixed orifice and flame arrester to a safe area. A secondary seal is installed adjacent to the primary seal, acting as a backup in the event of failure of the primary seal. Different pressure regulator maintain a differential of approximately 20 psi above suction pressure.

Buffer Air • •

•

The buffer air seal is a split-ring circumferential seal, adjacent to the inboard journal bearing of the compressor rotor. Air or Nitrogen is supplied to the seal at a regulated pressure. Small portion flows across the inner seal seal and out the secondary seal vent. The balance of the buffer air flows across outer portion seal into lube oil drain (mixed with LO draining from journal bearing) Different pressure regulator maintain a differential of approximately 10 psi between seal inlet and the secondary seal vent port

Dry Seal System Component Description •

Buffer Air DP Regulator – – – –

•

Buffer Air DP Transmitter – – – –

•

Normally open diaphragm and poppet type Secondary vent pressure and spring act on the OPEN side of the valve diaphragm Seal inlet pressure acts on the CLOSE side of the valve diaphragm The opposing forces maintain equilibrium at the pre-adjusted set point of the valve Normally 10 psid

Connected between seal inlet and secondary seal vent line Sends an electrical signal proportional to the pressure across the inboard buffer air seal to the control system If DP falls below 7 psi, and ALARM will be activated If DP falls below 4 psi, a Fast stop SHUTDOWN will be initiated.

Buffer Gas DP regulator – – – –

Normally open, Diaphragm and poppet type Suction pressure and spring pressure acting on the OPEN side of the diaphragm Buffer Gas inlet on the CLOSE side of the diaphragm The valve is adjusted to balance the diaphragm at nominal pressure of 20 psid

Dry Seal System •

Buffer Gas DP Transmitter – – –

•

Connected between suction (reference) line and the buffer gas seal inlet line If DP falls below 7 psi, with engine speed at 90 % or higher If DP falls below 4 psid, with engine speed at 90 % or higher

Buffer Gas Filter DP Transmitter –

Monitor DP filters, provides a proportional signal to control system indicating filter condition – If DP exceeds 40 psid, ALARM signal will be initiated

•

Buffer Gas Flow-Limiting Orifice – –

•

0.295 size orifice, installed in the buffer gas IN line Limits the flow of gas as the labyrinth seal wears and its clearances increases

Buffer Gas Flow-Monitoring Orifice –

0.25 size orifice, installed in the primary seal vent line, to measure seal leakage flow In the vent line

–

A relief valve, connected in parallel with the orifice, is adjusted to open at 30 psid, provides an escape gas in the event of a serious failure of the primary seal. Reducing the possibility of ovepressurizing the buffer air seal and contaminating the lube oil system with gas.

Dry Seal System •

Primary Seal Vent Alarm and Shutdown Transducer – – – –

Connected to the primary seal vent line Provide signal to the control system representing the absolute pressure at the vent port If the pressure at the vent line 12 psig, ALARM signal will be activated If the pressure at the vent line 20 psig, SHUTDOWN signal will be activated

NOTE The back pressure at the primary seal vent must not exceed 5 psig

SECONDARY SEAL VENT

2nd seal Hi Flow Alarm switch

PRIMARY SEAL VENT

R A A

A

S/D

S/D S/D BALANCE PISTON

A

BUFFER GAS

S/D

LO IN LO IN R

AIR / N2

Balance Piston & Seal • Balance piston adalah bagian dari rotor yang digunakan untuk mengurangi gaya axial • Balance Piston ada pada sisi discharge, setelah internal staging yang terakhir

Balance Piston & Seal (1)

Balance Piston & Seal (2)

Balance Piston

Balance Piston & Seal (3)

PERFORMANCE OF CENTRIFUGAL COMPRESSOR

Performance Evaluation Evaluasi Penting karena : Mengetahui existing Performance (Optimal atau Tidak) Mengetahui Kondisi Kompressor (Fouling, excessive seal wear dll) Mengambil keputusan perlu atau tidak compressor cleaning atau compressor Re-Staging

Adapun Performance Evaluation meliputi : -

Compressor Theory Physical Properties of Gas Head, Flow and Efficiency Compressor Performance Curve / Map Compressor Horse Power Performance Analysis and Their Problem A rise

Compressor Theory • Persamaan Euleur • Persamaan Bernouli • Hukum-hukum Thermodinamika – Process Adiabatik / Isentropik – Process Polytropic

Energi Gas • Terdiri dari : Head (tekanan) dan Flow • Horse Power = Head X Flow • Head adalah besaran enersi yang diberikan kepada gas untuk setiap satu besaran massa.

Gas Physical Properties • Specific Gravity • Ratio of Specific Heat • Compressibility factor

Specific Gravity (s.g) • Adalah : Perbandingan molecular weight dari gas mixture terhadap Molecular weight udara. • Molecular weight udara = 28.964 Mol weight gas mixture • SG = --------------------------------28.964

Compressibility factor (Z) • Adalah factor koreksi volume dari perhitungan gas ideal menjadi gas actual. • Harga Z selalu < 1

Compressibility factor (Z)

Sample of Gas Analysis

Perhitungan SG

Compression Head 53.35 x Z av x k x T1 Head

(k-1)/k

= ----------------------------------[ (P2/P1) SG x (k-1)

Head = Ft. Lbs force / Lbs mass. Z ave =Compressibility factor k

= Ratio of specific heat

T1

= Temperature gas suction (Deg R)

P1

= Pressure gas suction (psia)

P2

= Pressure gas discharge (psia)

SG

= Specific Gravity gas

-

1]

Horse Power Required 1.6417 x 0.001 x Head x Flow MMSCFD x SG HP = ---------------------------------------------------------------Efficiency

HP

= Horse power yang dibutuhkan oleh compressor yang tersedia pada shaft compressor.

Isentropic Efficiency (k-1)/k T1 [ (P2/P1)

-1]

Eff = ----------------------------------T2 - T1

Compressor Curve / Map Ada tiga macam Curve – Dimensional Curve – Semi-Dimensional Curve – Head vs Capacity (Flow) Curve Rule : The Head versus Capacity curve is the only curve necessary

Dimensional Curve Use for Bid evaluation Pressure versus Standard Flow Determines operating range Based on Constant Suction or Discharge Pressure No Longer of value after purchase decision

Can determine specific operating Condition Power & Speed

Shape of curve very demendent on base conditions Suction Temperature Suction Pressure Discharge Pressure Gas Composition

Semi-Dimensional Curve Use for Bid evaluation Pressure Ratio versus Standard Flow divided by pressure Determines operating range Based on Constant Suction or Discharge Pressure No Longer of value after purchase decision

Can determine specific operating Condition Power & Speed

Shape of curve very demendent on base conditions Suction Temperature Suction Pressure Discharge Pressure Gas Composition

Head versus Capacity Curve Only affected slightly by changes in base conditions – Suction and Discharge Temperature – Discharge Pressure – Gas Composition

Used to determine the condition of an operating compressor – Compare actual efficiency to nominal (curve) efficiency – Compare actual speed to nominal (curve) speed

Performance Diagnostics Method 1. Actual versus Nominal Data •

•

Actual Speed

Measured

Efficiency

Calculated (from measured data)

Nominal Speed Efficiency

From Head – Capacity curve From Head – Capacity curve

Performance Diagnostics Method 2.

Creates 9 possibilities EFFICIENCY

SPEED

COMMENTS

OK

OK

OK

LOW

Check speed, P1, P2, and SG measurement

OK

HIGH

Possible compressor damage

LOW

OK

Possible compressor damage, Check T1, 2

LOW

LOW

Data probably suspect, Check P1,2 and SG

LOW

HIGH

Possible comp. Damage. Check Flow measurement

HIGH

OK

Comp. Probably OK. Data possibly suspect. Check T1,2 measurement

HIGH

LOW

Comp. Probably OK. Data definitely suspect. Check T1,2 measurement

HIGH

HIGH

Comp. Probably OK. Data definitely suspect. Check T1,2 measurement

Compressor probably OK

Yard Valve Sequence

Yard Valve Sequence

Yard Valve Sequence