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Functional Analysis and Control System for the Thermosiphon Chiller. Lukasz Zwalinski PH/DT /PO - Cooling. Introduction. Cascade refrigeration system with R23 as low temperature refrigerant and R404a as high temperature refrigerant. C6F14 brine circuit

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functional analysis and control system for the thermosiphon chiller

Functional Analysis and Control System for the Thermosiphon Chiller

Lukasz Zwalinski

PH/DT/PO - Cooling

slide2

Introduction

Cascade refrigeration systemwith

R23 as low temperature refrigerant and

R404a as high temperature refrigerant

C6F14 brine circuit

Normal operation -64.93C to -70.25C

Warm operation -14.85C to -20.81C

liquid

tank

Normal operation evap.

Cascade

condenser

R404a

Water condenser

R23

Surface

USA15

cavern

Warm operation evap.

Air condenser

  • Main control actions for R23 circuit:
  • Flow control threw normal operation evap. => to ensure SH vapour condition
  • Compressor speed control => to mach required load
  • Hot gas injection control => if required capacity is less then capacity of the compressor
  • Economizer control => high pressure liquid refrigerant sub cooling
  • Main control actions for R404 circuit:
  • Flow control threw cascade condenser => to ensure SH vapour condition (Normal operation)
  • Compressor speed control => to mach required load
  • Hot gas injection control => if required capacity is less then capacity of the compressor (Warm operation)
  • Economizer control => high pressure liquid refrigerant sub cooling (Normal operation)
  • Air cooled condenser fan control in case of water failure

UX15

cavern

ATLAS ID

Detector

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide3

Introduction

  • Schneider Premium PLC based control system
  • UNICOS framework
  • System size (I/O number)
  • Chiller Brine + Water (Stephane’s talk)
  • EN-CV-DC hardware standard
  • Detector control system integration: same solution as already introduced by EN-ICE for Detector Gas Group

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide4

Control system architecture V1

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide5

Control system architecture V2

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide6

Split of responsibilities

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide7

Status

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide8

Functional analysis organization

  • In accordance with EN-ICE template functional analysis contains:
  • General process description
  • Process decomposition
  • UNIT A
  • 3.1 UNITA controlled devices description: type + parameters
  • 3.2 Operational states description
    • Definition
    • Transition condition
    • Logical sequences
    • Sub unit and actuators logic
  • 3.3 User command definition
  • 3.4 Computed variables
  • 3.5 UNIT / PCO Alarms
    • Hardware
    • Software
  • 3.6 Actuator alarms
    • Hardware
    • Software
  • 3.7 Actuator alarms parameters – recipes parameters
  • 3.8 Limiting conditions
  • 4. UNIT B …

EDMS1165941

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide9

Process decomposition

Chiller

System

Chiller 1

Chiller 2

Brine

Water

R404

R23

To be defined

To be defined

EV53003

EV53007

Has to be defined in next 2 weeks

maximum

Economizer High temperature

Economizer Low Temperature

CV59235

CV59326

CV59330

CV59331

CV59332

CV59333

CV59318

CV59314

Warm Operation Evaporator

Normal Evaporation Evaporator

CV59240

EV59246

Cascade Condenser

CV59232

CV59233

COMP59112

CV59301

CV59302

GT59364

F59505A

F59505B

F59505C

F59505D

Air Cooled

Condenser

COMP59502

CV59201

CV59202

CV59213

GT59263

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide10

P&ID vs process decomposition

Air Cooled Condenser

Economizer HT

Economizer LT

CascadeCondenser

CV59235

Normal operation evaporator

Warm operation evaporator

R404

R23

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide11

Chiller 1 – Option modes and operation states

  • Option modes:
  • MAINTANACE: In this state, all equipment is stopped and there is no way to re-activate actuators from the program. All interlocks related to this unit are disabled.
  • OPERATION: nominal state in which Chiller is operated

States:

[0] Stopped: Both compressors are switched off all outputs are off except either EV53003DO or EV53007DO

[1] Available for Warm Operation (WCC): The R404a compressor is not running, but is available to start, EV-53003 is confirmed open,EV-53007 is closed.The chiller is using the Water Cooled Condenser and the manual changeover valves have been set for this condenser. A C6F14 pump is confirmed as running.

[2] Available for Warm Operation (ACC): The R404a compressor is not running, but is available to start. EV-53003 is confirmed open, EV-53007 is closed.The chiller is using the Air Cooled Condenser and the manual changeover valves have been set for this condenser. Condenser fans are healthy and switched to auto. A C6F14 pump is confirmed as running.

[3] Available for Normal Operation: Both compressors are available to start. A C6F14 pump is confirmed as running and either EV-53003 or EV-53007 is open.

[4] Warm Operation with Air Cooled Condenser ACC: The R404a compressor is running. EV-53003 is open ,EV-53007 is closed. The R23 compressor is not required, so its status is ignored. Air Cooled condenser is running.

[5] Normal Operation: Both compressors are running. EV-53003 is closed, EV-53007 is open.

[6] Warm Operation with Water Cooled Condenser WCC: The R404a compressor is running. EV-53003 is open, EV-53007 is closed.The R23 compressor is not required, so its status is ignored. Water Cooled Condenser is running.

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide12

Chiller 1 – Transition conditions

  • T0 = Transition from any state to STOP
  • A C6F14 pump running = 0
  • EV-53003 AND EV-53007 = closed
  • EMSDI = 0
  • PSU1DI AND PSU2DI = 0
  • The R404a compressor {COMP-59502} is tripped
  • Chiller.RunOrder falling edge
  • T1 = Transition from STOP to Available Air Cooled Condenser
  • A C6F14 pump must be confirmed as running
  • Either EV-53003 or EV-53007 must be open
  • Master Emergency Stop healthy [EMSDI = 1]
  • Either PSU1 or PSU2 healthy [PSU1DI = 1 or PSU2DI = 1]
  • The R404a compressor is available or running
  • The manual changeover valves have been set for air cooled condenser operation.
  • At least three of the four air cooled condenser fans {F-59506A – F-59506D}
  • are healthy [F59506A_TDI - F59506D_TDI = 1] and
  • switched to Auto [F59506A_A - F59506D_A = 1]
  • T2 = Transition from STOP to Available Water Cooled Condenser:
  • A C6F14 pump must be confirmed as running
  • Either EV-53003 or EV-53007 must be open
  • Master Emergency Stop healthy [EMSDI = 1]
  • Either PSU1 or PSU2 healthy [PSU1DI = 1 or PSU2DI = 1]
  • The R404a compressor is available or running
  • The manual changeover valves have been set for water cooled condenser operation.
  • T3 = Transition from STOP to Available Normal Operation:
  • A C6F14 pump must be confirmed as running
  • Either EV-53003 or EV-53007 must be open
  • Master Emergency Stop healthy [EMSDI = 1]
  • Either PSU1 or PSU2 healthy [PSU1DI = 1 or PSU2DI = 1]
  • The R404a compressor is available or running
  • The R23 compressor is available or running
  • The manual changeover valves have been set for water cooled condenser operation.

T4 = Transition from Normal Operation to Warm Operation:

  • Whilst running in Normal Operation,
  • The R23 compressor has either been commanded off by the operator, or switched off at the compressor starter panel [R23 Compressor AUTODI = 0], or has tripped, or is not available, AND the C6F14 brine temperature TT53101< -21.0oC.

T5 = Transition from Warm Operation Water Cooled Condenser to Normal Operation:

  • R23 compressor unit is Available –AND
  • Manual Operator transition request from Warm Operation to Normal Operation

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide13

R404 - compressor PCO operation states and transitions

T0 = R404.RunOrder falling edge OR

the switch on the compressor starter control panel (AUTODI = 0, OFFDI = 1 OffSt).

T1 = ‘Starts per Hour’ timer is running OR Stop to Start timer is running

T2 = ‘Starts per Hour’ timer is NOT running AND

‘Stop to Start’ timer is NOT running AND

starter control panel switch is in the ‘ON’ position (AUTODI = 1, OFFDI = 0 OnSt) AND

(EV-53007 or EV-53003 is open) AND

C6F14 Pump running.

T3 = Chiller start command = Chiller.RunOrder

T4 = PT-59207 {R404a Compressor Discharge Pressure} <11.77 bara AND

Economiser is switched off (NOT EHT.RunOrder)

[0] Tripped: A ‘Full Stop Interlock’ has been implemented. The compressor is not running; one or more of the compressor operating parameters has reached a software trip threshold and stopped the compressor, or a hard wired protection device has stopped the compressor.

[1] Stopped: The compressor is not running, it is not tripped. The compressor has been commanded to stop either by the operator or by the switch on the compressor starter control panel (AUTODI = 0, OFFDI = 1).

[2] Waiting: The compressor is not running. It is not tripped. The starts per hour timer is running, or (EV-53007 and EV-53003 is not open), or C6F14 Pump not running.

[3] Available: The compressor is not running, it is not tripped, it is not waiting, the starter control panel switch is in the ‘ON’ position (AUTODI = 1 OFFDI = 0). The compressor is waiting for a command to start

[4] Running Auto: The compressor has been selected to ‘Auto’ on the local HMI and has been commanded to start and is running normally within the designed operating envelope and can vary its speed according to the R404a Compressor Speed Controller.

[5] Running Manual: The compressor has been selected to ‘Manual’ on the local HMI and has been commanded to start by the manual ‘soft key’ start button on the HMI and can vary its speed according to the local ‘soft keys’ Manual Speed Increase & Manual Speed Decrease.

[6] Running non economised: The compressor has been commanded to start and is running normally within the designed operating envelope and can vary its speed according to the R404a Compressor Speed Controller if selected to auto, or by the local ‘soft’ buttons on the HMI if selected to manual, but PT-59207 {R404a Compressor Discharge Pressure} <11.77 bara and the economiser is switched off

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide14

Summary logic description table example

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide15

Alarm parameters and recipes parameters

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide16

Computed variables

  • Description:
  • Discharge Temperature (Saturated)(K) (Tsat) is calculated from this equation:
  • Tsat = A + (B x (LnP)) + (C x ((LnP)^2)) + (D x ((LnP)^3))

Discharge Superheat = Discharge Temperature (Actual)(K) – Discharge Temperature (Saturated)(K)

  • Range <-35.0,60.0>
  • Dead band 0.085K
  • Tsat is available and archived in PVSS

Where A = 226.9570901

B = 20.82789774

C = 2.485671782

D = 0.208949075

P = PT-59207 {R404a Compressor Discharge Pressure} (bara)

Tsat = Tsat59207

Then:

R404-DSH = TT-59211 + 273.15 - Tsat

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO

slide17

Summary and what’s next?

Chiller Functional Analysis and I/O List accepted on 12.10.2011

Hardware Ethernet IP tests in progress.

In 2 weeks time I’ll start preparation of UNICOS object list

Thermosiphon workshop §5 20th October 2011 L.Zwalinski – PH/DT/PO