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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
http://32801010.pdf/http://32801010.pdf/

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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




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


OFF

ON


OFF

ON


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

Documents

32242040 Jul 97