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PETRONAS TECHNICAL STANDARDS
DESIGN AND ENGINEERING PRACTICE
TECHNICAL SPECIFICATION
CONTROL SYSTEM AND INSTRUMENTEDPROTECTIVE FUNCTIONS FOR FIRED EQUIPMENT
- System for a tangentially gas-fired CO boiler(S 24.036)
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PREFACE
PETRONAS Technical Standards (PTS) publications reflect the views, at the time of publication,of PETRONAS OPUs/Divisions.
They are based on the experience acquired during the involvement with the design, construction,operation and maintenance of processing units and facilities. Where appropriate they are basedon, or reference is made to, national and international standards and codes of practice.
The objective is to set the recommended standard for good technical practice to be applied byPETRONAS' OPUs in oil and gas production facilities, refineries, gas processing plants, chemical
plants, marketing facilities or any other such facility, and thereby to achieve maximum technicaland economic benefit from standardisation.
The information set forth in these publications is provided to users for their consideration anddecision to implement. This is of particular importance where PTS may not cover everyrequirement or diversity of condition at each locality. The system of PTS is expected to besufficiently flexible to allow individual operating units to adapt the information set forth in PTS totheir own environment and requirements.
When Contractors or Manufacturers/Suppliers use PTS they shall be solely responsible for thequality of work and the attainment of the required design and engineering standards. Inparticular, for those requirements not specifically covered, the Principal will expect them to followthose design and engineering practices which will achieve the same level of integrity as reflectedin the PTS. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from hisown responsibility, consult the Principal or its technical advisor.
The right to use PTS rests with three categories of users :
1) PETRONAS and its affiliates.2) Other parties who are authorised to use PTS subject to appropriate contractual
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TABLE OF CONTENTS
1. INTRODUCTION1.1 SCOPE1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS1.3 DEFINITIONS AND ABBREVIATIONS1.4 CROSS-REFERENCES
2. GENERAL
3. FUNCTIONAL (OPERATIONAL) DESCRIPTION3.1 LOAD CONTROL3.2 AIR/FUEL RATIO CONTROL3.3 START-UP
4. TECHNICAL DESCRIPTION.
4.1 IMPLEMENTATION CONSIDERATIONS.4.2 LOCATION OF ALARMS, SWITCHES, ETC.4.3 CALCULATION FORMULAE4.4 DESCRIPTION OF INSTRUMENTED PROTECTIVE FUNCTIONS4.5 IPF CLASSIFICATION AND CAUSE AND EFFECT DIAGRAM
5. REFERENCES
APPENDICES
APPENDIX 1 Functional logic diagrams for a tangentially gas-fired CO boiler
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1. INTRODUCTION
1.1 SCOPE
This PTS specifies requirements and gives recommendations for control systems andinstrumented protective functions for atangentially gas-fired CO boiler.This PTS shall notbe used for any other equipment or firing configuration.
This PTS contains a control and IPF narrative and logic diagrams and refers to a standardspecific process engineering flow scheme.
This PTS shall be used together with Standard Drawing S 24.036.
This PTS is written for systems which use DCS for control and monitoring and PLC andSolod State / Magnetic core type Instrumented Protective Functions. Accordingly, more usehas been made of inverted signals than would have been the case for relay type IPFs.
1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS
Unless otherwise authorised by PETRONAS, the distribution of this PTS is confined tocompanies forming part of PETRONAS Group, and to Contractors nominated by them.
This PTS is intended for use in oil refineries.
If national and/or local regulations exist in which some of the requirements may be morestringent than in this PTS the Contractor shall determine by careful scrutiny which of therequirements are the more stringent and which combination of requirements will beacceptable as regards safety, economic and legal aspects. In all cases the Contractor shallinform the Principal of any deviation from the requirements of this PTS which is consideredto be necessary in order to comply with national and/or local regulations. The Principal maythen negotiate with the Authorities concerned with the object of obtaining agreement tofollow this PTS as closely as possible.
1 3 DEFINITIONS AND ABBREVIATIONS
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1.3.3 Abbreviations
ARWU Anti reset wind-up
CO Carbon monoxide
DCS Distributed control system
IPF Instrumented protective function
MCR Maximum continuous rating
PEFS Process engineering flow scheme
PLC Programmable logic controller
SRF Standard refinery fuel
TSOV Tight shut off valve
1.4 CROSS-REFERENCES
Where cross-references to other parts of this PTS are made, the referenced section numberis shown in brackets. Other documents referenced by this PTS are listed in (5).
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2. GENERAL
This PTS shall be used as the basis for the control systems, IPFs, narratives, functionallogic diagrams and PEFS for the installation for which it has been specified by the Principal.
The Contractor shall prepare installation-specific narratives based on this PTS, and shalladd relevant tag numbers, set points, controller configurations, etc. The installation-specificnarratives shall not contain general information which is not relevant to the specificinstallation.
Like this PTS, the narrative shall contain a functional description including operationalaspects and a detailed technical description.
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3. FUNCTIONAL (OPERATIONAL) DESCRIPTION
3.1 LOAD CONTROL
Flow control is the lowest level of control function for fuel gas and combustion air.
Minimum combustion air flow is ensured by an adjustable mechanical minimum stop on thecombustion air damper, while maximum combustion air flow is limited by the capacity of theblower and burner resistance.
Minimum fuel gas flow is ensured by a minimum stop pressure controller which guaranteesa minimum burner load, irrespective of the number of burners in operation. Similarly,maximum burner load is limited by a maximum stop pressure controller.
Note: The fuel gas pressure control limiter does not provide absolute limits to burner load since this is also
affected by variations in the density of the fuel gas.
In addition to the minimum stop fuel pressure controller, the fuel control valve is providedwith a mechanical minimum stop. This is adjusted to correspond to minimum load with onlyone burner in operation, and acts as a pre-set valve position for start-up of the first burner.
The control system works as follows:
The heat input from the regenerator off-gas (sensible heat and heat of combustion) iscalculated on the basis of the total air flow to the regenerator (including catalyst transportair), the CO content in the off-gas and the temperature of the off-gas to the boiler, and isconverted into SRF equivalent values.The SRF equivalent of the sensible heat in the off-gas is subtracted from the output signal ofthe master steam flow controller. The resultant signal, representing the total fuel demand(including CO), is then passed to the fuel gas flow controller via the air/fuel ratio controlsystem.The SRF equivalent (in terms of stoichiometric air requirement) of the CO is subtracted fromthe required fuel flow signal going to the fuel gas flow controller.The SRF equivalent (in terms of stoichiometric air requirement) of the CO is added to themeasured fuel gas flow before this signal is fed to the air/fuel ratio control scheme.
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A similar system applies to the fuel gas flow, as follows:- the measured combustion air flow passes through a "minimum air/fuel ratio" relay (with a
setting typically 10% lower than the normal air/fuel ratio, and the signal provides amaximum limit (via a low selector) to the fuel demand signal to be sent to the fuel gasflow controller setpoint (after subtraction of the SRF equivalent (in terms of air required)CO flow)). If the fuel demand increases, and the actual combustion air flow does notfollow, this signal will limit the increase in fuel flow demand. The control system changesfrom a "parallel control" system to an "air leading" system (air increase leads fuelincrease) after the low selector has limited the increase in fuel gas flow.
Since the system operates such that burners can only be operated above minimum stopconditions if all burners are in operation, the air/fuel ratio control does not need to becorrected for operation with less than the total number of burners in operation. The
mechanical minimum stop on the combustion air damper (set at 35% flow) guaranteessufficient air for minimum stop operation.
3.3 START-UP
Each burner is equipped with individual start and stop switches for the ignition burner as wellas for opening and closing the fuel gas burner TSOVs.
The system is equipped with an automatic purge sequence. Upon activation of the "purgestart" the common air damper is opened fully for the period of the purge timer.
After the purge time has elapsed and if other conditions are healthy, ignition burners can bestarted by activating the ignition burner start buttons.
A new purge is only required in case of a combustion air failure. After any other trip a waitingtime of 1 minute suffices.
After an ignition burner has successfully started, its main burner can be started up byactivating the main burner start button. If the main burner is not started within 15 minutes,the ignition burner is stopped again.
Fi e seconds after starting the main b rner the igniter is a tomaticall stopped Thereafter
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Above 35% MCR, the boiler is considered as operating under 'fire ball' conditions. Under'fire ball' conditions the loss of the "flame" signal of a single flame detector does not lead toa trip of the corresponding main burner. If 2 or more flame detectors fail to detect a flamethe regenerator off-gas diverted to stack, the relevant fuel gas burners trip, and theremainder trip to minimum firing conditions.Once the 'fire ball' conditions are reached, regenerator off-gas is allowed to be introducedinto the combustion chamber. Upon loss of 'fire ball' conditions, the CO is diverted toatmosphere if not all flame detectors indicate flames present.
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4. TECHNICAL DESCRIPTION.
4.1 IMPLEMENTATION CONSIDERATIONS.
Both minimum and maximum fuel gas pressure controllers (PIC-1 and PIC-2) shall belocked in auto mode. The operator shall not be able to change the setpoint of the maximumpressure controller (PIC-2). The operator may be given limited control over the setpoint ofthe minimum pressure controller (PIC-1) up to 2 times the minimum pressure. The latterflexibility is sometimes useful to prevent flame loss due to too low a pressure whenmanipulating burners.
The minimum and maximum pressure controllers (PIC-1 and PIC-2) shall be fast-acting (likecompressor anti-surge controllers).
If the master controller TRC-1 and fuel gas flow controller FRC-1 are forced to manual with0% output (minimum stop) the operator shall not be able to change their mode or output.
The fuel gas control valve shall have an equal percentage characteristic, and in this way theperformance of the minimum stop pressure controller is independent of the number ofburners in operation.
The interfacing between the PLC system and the DCS shall be hard-wired for thoseconnections which are safety related (no serial link). This applies for example to the force tominimum stop. Although the latter is classified as IPF class II, a delay (related to the serial
link) may ultimately activate a total furnace trip initiator.The anti reset wind-up (ARWU) to the fuel gas FRC and the minimum and maximumpressure controllers is provided to ensure bumpless transfer when one controller overridesanother.
ARWU protection shall also be implemented on the master temperature controller TRC-1and the oxygen controller QRCA-1.
If the fuel gas FRC-1 is not on cascade, the master steam flow controller shall be initialisedto the total fuel flow.
If th b ti i i t d th QRC h ll b i iti li d t th ( t)
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4.3 CALCULATION FORMULAE
The following formulae shall be used:
Y1) Calculates regenerator off-gas flow to CO boiler.
Moff-gas = 1.1 * Total air flow to regenerator * Opening of two-way slide valve to CO
boiler (as a fraction of fully open)
(Total air flow to regenerator= Main air flow + Transport air flow)
Y2) Calculates SRF (Standard Refinery Fuel) equivalent of sensible heat in off-gas.
CO = M * (T - T ) * CpLHV
[tSRF / d]sensible heat off -gas off -gas stack off -gasSRF
where:Toff-gas = Temperature of off-gas to boiler
Tstack = Stack temperature [200 C]
Cpoff-gas = Specific heat off-gas [1.16 kJ/kgC]
LHVSRF = Lower heating value SRF [40 500 kJ/kg]
Y3) Calculates amount of CO in off-gas.
M = Fr * M *MW
MW[tCO / d]CO CO off-gas
CO
off-gas
where:FrCO = Volume fraction of CO in off-gas
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Y5) Calculates maximum allowable fuel flow
Output=Measured air flow
0.9 * 13.66 (0.8 + 0.8 * QRC)[tSRF/ d]
in which: QRC = Output of oxygen controller [signal 0-1]
The formula limits the air/fuel ratio between 0.8 and 1.6 (times 0.9).
Y6) Subtracts SRF equivalent of CO (in terms of air equivalent) from fuel demand.
Output = Total fuel demand - M *SAR
SARCO
CO
SRF where:SARCO = Stoichiometric air requirement of CO [2.47 kg air/kg CO]
SARSRF = Stoichiometric air requirement of SRF [13.66 kg air/kg SRF]
Y7) Adds SRF equivalent of CO (in terms of stoichiometric air requirement) to measuredfuel gas flow (Mfuel SRF).
M = M + M *SAR
SAR[tSRF/ d]total SRF fuel SRF CO
CO
SRF
Y8) Sets a minimum limit for the combustion air flow.
Output = 0.9 * Mtotal SRF
Y9) C l l t th i d i fl
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COoff-gas = 1.16 kJ/kg.C
Y15) ARWU compensation block
external feedback = Total fuel SRF measured + COsensible heat
4.4 DESCRIPTION OF INSTRUMENTED PROTECTIVE FUNCTIONS
The IPFs are described by the functional logic diagrams (Appendix 1) and by the IPFnarrative given below.
The functional logic diagrams are set up in a modular structure. This section follows the
same structure but only describes the main modules. Assisting modules such as the"general trips" module are not described separately. Their functionality is described in themodules where they are relevant.
4.4.1 Safe atmosphere module
The function of this module is to continuously check for, and if necessary re-establish bypurging, a safe atmosphere for firing the boiler.
If: i. the combustion air blower is running; and
ii. the fuel gas header TSOVs and the individual main burner TSOVs are closed; and
iii. the two-way slide valve is in the "boiler bypass" position; and
iv. the local and panel trip switches are in the healthy position; and
v. no flame is detected (start condition only); and
vi. the "safe conditions" signal is not present; then
the purge sequence can be started by activating the "start purge" switch.
Thi i iti t th f ll i f th i d A ffi i t i fl f th
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The damper only re-opens 2 minutes after the two-way slide valve has been detected inbypass position.A latch circuit prevents the damper from reopening automatically upon a healthy FZA signal(this to prevent erratic behaviour which could lead to introduction of air into a hot, CO-filled
fire box).
4.4.3 Minimum stop module
The purpose of this module is to control the set and release of the fuel minimum stops.
If: i. the air/fuel ratio is healthy; and
ii the module receives signals that all fuel gas burners are in operation; and
iii. the fuel gas pressure is not above high high; then
the fuel gas FRC can be taken into operation by activating the gas minimum firing reset inthe control room.
4.4.4 Igniter header module
The function of this module is to monitor all the conditions required to open and close theigniter header TSOV and to control this valve.
The igniter header TSOV is fully governed by the igniter modules. As long as one of the
igniter burner modules produces an "open igniter header" signal the igniter TSOV is open.
4.4.5 Fuel gas header and vent module
The function of this module is to monitor all the conditions required to open and close thefuel gas header and vent TSOVs and to control these valves.
There are two parallel TSOVs to facilitate tightness testing during operation. By means of aselector switch either gas header A or gas header B can be selected to be in operation.
If: i. the safe atmosphere module produces the "safe conditions" signal; and
ii th diti ( t i ) h lth d
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ii. the module does not receive a "stop igniter" pulse from the gas burner module;and
iii. there is no high level in the fuel gas KO drum; and
iv. the safe atmosphere module produces a "safe conditions" signal; and
v. the igniter stop button is not activated; then
the igniter can be started by activating the igniter start button.
The module then produces the following signals:
a. open igniter header
b. open igniter TSOV
c. ignition spark signal for a period of about 10 seconds.
After the flame stabilisation timer has run out (after about 15 seconds) the ignition flameshall be detected by the ionisation rod, and an "ignition flame present" signal is sent to therespective main burner module.
If the igniter start trial was unsuccessful, restart is inhibited for a period dictated by theigniter restart inhibit timer (about 30 seconds). This timer is installed to prevent damage tothe ignition transformer.
An indefinite number of restarts of the igniter can be attempted without a new purge cyclebeing required. It is assumed that the capacity of the igniter is sufficiently low to ensure thatthe overall gas/air mixture is below the lower explosion limit.
After the igniter has been successfully started, it will run for a maximum period of 15minutes. It will be automatically stopped by the main burner module 5 seconds after openingof the main burner TSOV.
After the main burner has started the igniter can be restarted at any time (for testingpurposes). After 15 minutes the igniter is stopped again.
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If any one of the above conditions fails, the gas burner TSOV is closed, the signal to theburner count module drops off, and the "open gas header" signal disappears. If no other gasburner modules produce an "open gas header" signal the gas header TSOV is closed andthe vent TSOV opened. Moreover, if no other main burners are in operation a complete new
purge sequence is required.
The start inhibit timer inhibits the start of any ignition burner for 1 minute, after anunsuccessful start or after a stop of any burner.
If the burner TSOV proximity switch does not detect that the valve is closed within 15seconds after initiating valve closure, an alarm is given.
Individual burners shall not be stopped if CO gas is lined up to the boiler. Therefore, the"stop gas burner" signal is overridden while CO gas is being burned in the boiler.
4.4.8 Flame detection and fire ball module
The function of these modules is to monitor the individual flame detector signals and toprovide relevant trip signals.
The module receives the individual detector signals and the "steam production above 35%MCR" signal. It provides the following signals:
If: i. at least 3 flame detectors produce a flame-on signal; and
ii the steam production is above 35% MCR; thenthe module produces a "fire ball conditions" signal, which is used to allow CO off-gas to beintroduced.
If: i. the "fire ball conditions" signal is healthy; or
ii. all fuel gas burners are in operation; then
the module produces a "fire ball or all burners in operation" signal, which is used as arequirement to continue to operate on CO off-gas.
If i th "fi b ll diti " i l i h lth
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4.4.10 Burner TSOV tightness test module
To allow the tightness of the individual burner gas TSOVs to be tested during shutdown onlythe gas header TSOV can be opened for a short period by pressing HS-9.
Pressing of this button will result in opening of the header TSOV only if:
i. all gas burner TSOVs are confirmed closed; and
ii. neither the "purge ready" signal nor the "purge in progress" signal is present.
If these conditions are effective and HS-9 is activated, the header TSOV is opened for about5 seconds. The vent is closed at the same time and is kept closed during the test. Duringthe whole testing period starting is interlocked via the "inhibit start" signal to the safeatmosphere module.
After the testing period has expired (normally about 5 minutes) the vent is opened and the"inhibit start" signal disappears.
4.5 IPF CLASSIFICATION AND CAUSE AND EFFECT DIAGRAM
The IPFs described in (4.4) have been classified and implemented in accordance withPTS 32.80.10.10. The classification results are indicated in the cause and effect diagram(Table 1).
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Table 1 Cause and effect diagram
Initiators Actions 1)
TAG Service Abort/Inhibit
startsequence
Headerfuel gas
TSOVsclose
Ventfuel gas
TSOVopen
Two-wayslide
valve inby-passmode
Trip tomininum
firingfuel gas
Headerigniter
TSOVclose
Mainfuel gas
burnerTSOVclose
Igniterburner
TSOVclose
CObackflow
protectiondamperclose
purgesteam
valveopen
FZA-01-LL Combustion air - III II III 0 0 0 0 III 6) III 6)
FZA-02-L Combustion air (for purging) III - - - - - - - - -
XZA-01-LL Air/fuel ratio - - - - II - - - - -
PZA-01a-HH Fuel gas - - - II - - - - -
PZA-01b-H Fuel gas III IV 5) II 5) III 5) 0 5) 0 5) 0 5) 0 5) - -
HZA-01/02 Manual trips 0 III II III 0 III 0 0 - -
LZA-01-HH Fuel gas KO drum - III II III 0 II 0 0 - -
GBSA-01-S Fuel gas control valve in start position III - - - - - - - - -
GBSA-02/03-C Fuel gas header TSOVs closed III - - - - - - - - -
GBSA-04 By-pass Slide valve in by-pass position III - - - - - - - III 6) III 6)
LZA-02-LL Boiler drum level - IV II III 0 0 0 0 - -
GBSA-14-C Vent TSOV closed - - - - - - - - - -
XZA-11/21/31/41 Ignition flame detection III/- 2) - - - - 0 - 0 - -
XZA-12/22/32/42 Main flame detection - - - - - - IV 0 - -
3 off XZA-12/22/32/42 At least 3 main flame detectors3) II - - III - - - - - -
FZA-xx-LL Steam flow >35% MCR 3) II - - III - - - - - -
4 off XZA-12/22/32/42 All main flame detectors - I II III 4) III 4) - - - - -GBSA-14-n4-C Gas burner TSOV closed III - - - - - - - - -
NOTES:1) - = No action
0 = Unclassified, but serves purpose in sequence control
II = IPF class IIIII = IPF class IIIIV = IPF class IV
2) In case the main flame detector cannot detect neighbouring/opposing flames the ignition flame detection is unclassified.3) Combination of 3 flame detectors and FZA-xx forms "fire ball condition".4) Only in case 'fire ball" conditions are not healthy.
5) High fuel gas pressure only initiates a total trip in case of failure of trip to minimum firing.6) CO back-flow protection is only activated in case of low air flow AND slide valve is detected in bypass position (GBSA-04).
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5. REFERENCES
In this PTS, reference is made to the following publications:
NOTE: Unless specifically designated by date, the latest edition of each publication shall be used, togetherwith any amendments/supplements/revisions thereto.
PTS
Classification and implementation of instrumentedprotective functions
PTS 32.80.10.10
STANDARD DRAWINGS
Combustion control and safeguarding scheme for atangentially gas-fired CO boiler
S 24.036
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APPENDIX 1 Functional logic diagrams for a tangentially gas-fired CO boiler
Amended PerCircular 57/97
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Logic 36 Sheet 0
FURNACE SAFEGUARDING LOGICS
Logics 36Sheet 0
Furnace safeguarding logics for S 24.036
Logics for a tangentially, gas fired, CO boiler.
Reference:S 24.036, Standard drawing for a system for an automaticallystarted, tangentially, gas fired, CO boiler.
Sheets:
1. Safe atmosphere2. Burner & Valve status.3. General trips & CO back flow protection.4. Minimum stop5. Igniter header
6. Fuel gas header + vent7. Gas firing trips8. Fuel gas TSOV selection
9. Fire ball & flame detection.10. CO off-gas firing.
12. Igniter burner 113. Fuel gas burner 1
98. Burner TSO test99. Status indications, alarms, switches
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Logic 36 Sheet 1
HS-1
Start purge
Status
"Purge inprogress"
OFF
ON
Status"Purgeready"
OFF
ON
0t
System : Logics for a tangentially, gas fired, CO boiler.Module : Safe atmosphere.
Logic 36Sheet 1
InterlockTSO testing
Safe
conditions
All valves closed
Required purgeair flow
Combustion air
flow healthy
No flame detected
1-398
&
&
>
&>
&
&
&
9-61
2-11
3-21
3-11
HZ-1Local trip
HZ-2
Controlroom trip
Status"Safeconditions"
OFF
ON
D
CS
Combustionair FRCmaximum
MAX
1-1
6
1-43
1-1112
1-1442
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Logic 36 Sheet 2
System : Logics for a tangentially, gas fired, CO boiler.Module : Burner & valve status.
Logic 36Sheet 2
2-11
Burner 1 Open fuelgas TSOV
Burner 4 Open fuelgas TSOV
Any gas burnerTSO open
(Not) inhibit
burner start
Any gas burner TSO open
Start inhibit timer
43-52
13-52
2-26
Start inhibit timer
Open gas header Aor header Adetected closed
Open gas header B
or header Bdetected closed
Open 2-way slidevalve to boiler or2-way slide valvedetected in bypass
position.
Burner 1 OpenTSOV or TSOV
detected closed
Burner 2 OpenTSOV or TSOVdetected closed
N3-92
13-92
8-42
10-12
8-2
2start inhibit timer
&
0t
&
All valves closedconditions
2-1112
2-N1N2
98-12
Inhibit startfor TSO testing
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Logic 36 Sheet 3
t0
0t
t0
System : Logics a tangentially, gas fired, CO boiler.Module : General trips & CO back flow protection.
Logic 36Sheet 3
Safe conditions
>
>
>
>
>
Alarm
"Low comb.air flow"
OFF
ON
3-11
3-21
3-34
3-4
6
Status"Purge flow
healthy"OFF
ON
backflowprotection
damperC
O
2-way slide valvedetected in bypass
position purge steam
valveC
O
Alarm"Low A/Fratio"
OFF
ON
Alarm "backflow protectionactivated"
OFF
ON
Alarm"Low boilerdrum level"
OFF
ON
MOS
1-4
3
FZA-02Combustionair flow
>LL
FZA-01
Purgeair flow
>LL
MOS
MOS
XZA-01Air-fuelratio
>LL
LZA-02Low boilerdrum level
>LL
10-23
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Logic 36 Sheet 4
System : Logics for a tangentially, gas fired, CO boiler.Module : Minimum stop.
Logic 36Sheet 4
>
DCS
Fuel gasFRC
manual 0%MIN
Status"Fuel gas on
min.stop"OFF
ON
HS-2 Reset
gas firingminimum stop
A/F ratiohealthy
All burners in
operation
Burner 1
in operation
Burner 4
in operation
Fuel gas
pressure
not high high
Fuel gas
pressurenot high
3-3
4
13-64
43-6
4
7-2
4
7-4
4
4-1
9&
&
>
(NOT) fuel gas
minimum stop
failure
(via 30 sec. ramp)
4-16
Alarm Gasmin.stop
failureOFF
ON
0 t
t = 30 sec
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Logic 36 Sheet 5
System : Logics for a tangentially, gas fired, CO boiler.Module : Igniter header.
Logic 36Sheet 5
IgniterheaderTSOV
O
Open igniter header(for burner 1)
12-15
Open igniter header(for burner 4)
42-15
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Logic 36 Sheet 6
HS-4Stop fuel
gas firing
t0
Healthy for
fuel gas firing
System : Logics for a tangentially, gas fired, CO boiler.Module : Fuel gas header & vent.
Logic 36Sheet 6
No high level infuel gas KO drum
(Not) failure trip tominimum stop
Any burnerTSO open
Low boiler drumlevel
Safe conditions
7-16
4-16
3-4
6
2-26
1-16
GBSA-01control valve
start position
MIN
Alarm"CV not instart position"OFF
ON
6-14
43
6-11
13
>
t0
Open fuel gasheader
Open gas header
for TSO test
5 sec
&
98-26
GBSA-09
vent TSOlimit switch
C
6-18
6-210
Vent TSO
C
O
Alarm"Vent TSOclosing failure"
OFF
ON
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Logic 36 Sheet 7
System : Logics for a tangentially, gas fired, CO boiler.Module : Gas firing trips.
Logic 36Sheet 7
>
Alarm
"High levelKO drum"
OFF
ON
7-16MOS
LZA-01Fuel gasKO drum
>
Alarm"High fuelgas pressure"OFF
ON
7-24
7-44
MOS
PZA-01aFuel gas
pressure
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Logic 36 Sheet 8
GBSA-02FG header Alimit switch
C
GBSA-03FG header B
limit switch
C
HS-3
FG headervalve selector
A
B
Status
"FG headerA in use"
OFF
ON
Status"FG header
B in use"OFF
ON
Alarm
"FG header Aclosing failure"
OFF
ON
Alarm"FG header B
closing failure"OFF
ON
Fuel Gasheader A
C
O
Fuel Gas
header BC
O
8-2
2
8-1
2
6-1
8
MOS
MOS
Open gas header A
or header Adetected closed
Open gas header Bor header B
detected closed
Open fuel gasheader
t0
t0
0t
t0
t0
&
&
>
>
>
&
&
0t
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Logic 36 Sheet 9
XZA-12Burner 1Flame
>LL
XZA-22Burner 2flame
>LL
XZA-32Burner 3flame
>LL
XZA-42Burner 4flame
>LL
9-113
9-223
9-333
9-4
43
9-710
9-61
Burner 1flame healthy
Burner 2flame healthy
Burner 3flame healthy
Burner 4flame healthy
No flame detected
Fire ballconditions
Fire ball conditionsor all burners inoperation
All burners inoperation
System : Logics for a tangentially, gas fired, CO boiler.Module : Fire ball & flame detection.
Logic 36Sheet 9
Alarm burner 1No flamedetected
OFF
ON
Alarm burner 2No flamedetected
OFF
ON
Alarm burner 3No flamedetected
OFF
ON
Alarm burner 4No flamedetected
OFF
ON
Alarm Notall flamesdetected
OFF
ON
AlarmNo fire-ballconditions
OFF
ON
>
>
>
>
>
&
>2
Alarm"Steam flow
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Logic 36 Sheet 10
System : Logics for a tangentially, gas fired, CO boiler.Module : CO off-gas firing module.
Logic 36Sheet 10
>
>
>
D
CS
CO off gas
HIC-1manual 0%
MIN
AlarmCO in
bypass modeOFF
ON
2-way slidevalve in
bypass modeBy-
pass
HS-5 Start
CO firing
Fire-ball
conditions
Fire ball conditionsor all burners in
operation
Fuel gas header
TSO open
Open 2-way slidevalve to boiler or
valve detected inbypass position
2-way slide valve
detected in bypassposition
CO gas lined up
to boilerExternaltrip conditions
9-710
9-510
6-2
10
10-1
2
10-23
10-1113
10-41
43
HS-6
StopCO firing
&
EXT
t0
GBSA-04
2-way slidevalve bypass
By-
pass
Alarm
"Slide valveclosing failure"
OFF
ON
>
&
MOS
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Logic 36 Sheet 12
System : Logics for a tangentially, gas fired, CO boiler.Module : Igniter 1.
Logic 36Sheet 12
XZA-11
Flame rod
igniter 1
>LL
Igniter 1TSO
C
O
Sparkerigniter 1
OFF
ON
Status"Igniter 1 on"
OFF
ON
12-15
12-2
13
Open igniterheader
Igniter 1 present
Spark timer
HS-12
Stopigniter 1
HS-11Startigniter 1
13-412
2-11
12
7-1112
1-1112
(Not) stop igniter 1
(Not) burner start
inhibit
Not high level
fuel gas KO drum
Safe conditions
10 sec
Max igniteroperation timer
Igniter 1 startinhibit timer
Igniter start timer
15 sec
15 min.
>
&
>
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Logic 36 Sheet 13
HS-14Stop fuel
gas burner1
12-213
6-1113
9-1
13
10-1113
Igniter 1 on
Healthy forgas firing
CO gas lined up toboiler
Burner 1Flame healthy
Burner start timer
GBSA-14Burner 1TSO closed
C
HS-13
Start fuelgas burner 1
Stop igniter
Burner 1 TSOC
O
Status"Gas flame
burner 1 on"OFF
ON
Alarm GasBurner 1 TSO
closing failureOFF
ON
13-4
12
13-64
13-52
13-898
13-72
Burner 1TSO open
(NOT)
Stop igniter 1
Burner 1 on
Burner 1 GasTSOV closed
Burner 1 Open gasTSOV or TSOV
detected closed
System : Logics for a tangentially, gas fired, CO boiler.Module : Fuel gas burner 1.
Logic 36Sheet 13
5 sec
1
>
>
&
>
TSO 1 closing timer
t0
&
MOS
0t
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Logic 36 Sheet 98
13-898
43-898
1-398
Burner 1 TSOclosed
Burner 4 TSO
closed
Interlock burnerTSO testing
HS-9Start test
t0 Status"tightness testin progress"OFF
ON
98-12
98-26
Inhibit start
Open main and
close vent
System : Logics for a tangentially, gas fired, CO boiler.Module : Manual burner TSO tightness test.
Logic 36Sheet 98
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Logic 36 Sheet 99
HS-1 Start purge
HS-3 Gas header
selector
HS-9 Test burner
TSO's
HS-3 Reset fuel gas
minimum stop
Low combustion
air flow
FD Fan failure
Fuel gas controlvalve not in start
position
High fuel gaspressure
Failure trip tominimum firing
Air/fuel ratio lowHigh level fuelgas KO drum
Vent closingfailure
Purge inprogress
Fuel gas onminimum stop
TSO test in
progress
Fuel gas header
B selected
Fuel gas headerB closing failure
Fuel gas headerA closing failure
Not a ll flamesdetected
No fire ballconditions
Steam flow
Recommended