DOE/MC/ /C0148 DOE/MC/ /C0148

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DOE/MC/23167-9

3/C0148

DOE/MC/23167--93/C0148

DE93 005195

Conceptual

Design

of a Gas Turbine

for PFBC Applications

Authors:

Bannister,

R.L.

McGuigan,

A.W.

Risley,

T.P.

Smith, O.J.

Contractor:

Westinghouse

Electric Corporation

4400 Alafaya

Trail

Orlando,

FL

32826-2399

Contract

Number:

DE-AC21-86MC23167

Conference

Title:

Ninth Annual

Coal-Fueled

Heat Engines,

Advanced

Pressurized

Fluidized

Bed Combustion

(PFBC) and Gas Stream Cleanup

Systems

Contractors

Review

Meeting

Conference

Location:

Morgantown,

West Virginia

Conference

Dates:

October

27-29,

1992

Conference

Sponsor:

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DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report has been reproduced directly from the best available copy.

Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831; prices available from (615)576-8401, FrS 626-8401.

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t

Conceptual

Design

of a Gas Turbine

for PFBC

Applications

CONTRACT INFORMATION

Contract Number

DE-AC21-86MC23167

Contractor

Westinghouse ElectricCorporation

4400 Alafaya Trail

Orlando,Florida 32826-2399

(407) 281-2000

Contractor Project Manager

Ronald L. Bannister

Principal Investigators

ArthurW. McGuigan

Thomas P. Risley

Owen J. Smith

METC Project Manager

Donald W. Gelling

Period of Performance

July 24, 1986 to April 30, 1993

Schedule

FY92 Conceptual

Design

of a Gas Tubine

for PFBC Application

1992

1993

A

M

J

A

S

O

N

D

J

F

M

A

Turbine

andPlant

Performance

Blading

andCooling

Arrangement

Casing

Arrangement

Turbine

SystemModification

Startup

Combustion

System

Interconnecting Piping

'

"

OBJECTIVE

to assure that the Westinghouse 251B12

combustion turbine can be suitable for

First generation pressurized fluidized bed

demonstration phases of this technology, such as

(PFBC) technology has potential advantages

DesMoines Energy Center 1 (DMEC-1), as it

which include: lower capital cost, improved

progresses toward commercial deployment.

environmental performance, shorter lead times,

higher efficiency and enhanced fuel flexibility.

BACKGROUND INFORMATION

Many advances have been made in this

Coal firing with combustion turbines

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technologies. It will be demonstrated as part of

• ambient temperature

the Clean Coal 1TIinitiative.

,

pressure drop across PFBC system

• flue gas composition

PFBC technology is applicable for new

• compressor inlet flow

installations, replacement of existing equipment

,

burner outlet temperature (BOT)

as well as repower and retrofit. Included with

these options is the opportunity to reduce

dependency on fuel oil and well as enhancing

Task 12.2 Analysis of Optimum Blading and

environmental performance and increasing

Cooling

efficiency.

This task consists of defining:

The turbo-machinery will require design

changes to meet the requirements for PFBC

• engine design parameters for key

application. The major change to the

components to the initial application of

combustion turbine take piace in the center

this technology to DMEC-1

section. This section will include provisions to

supply compressed air to the PFBC as well as

• deviations from the standard 251B12

receive vitiated air from the PFBC. These

efforts also have the objective of reducing the

• analysis of compressor modifications

degree of change from a standard unit.

required for reduced flow

Under a clean coal program a first generation

• inlet guide vane configuration

PFBC demonstration will take piace as the

DesMoines Energy Center. For this

• thrust load capability

demonstration it will be necessary to remove

two stages from the 251B 12 compressor. This

• cooling requirements

will make the air supplied by the compressor

suitable for the PFBC system. The results from

this program will be applicable to the DMEC-1

Task 12.3 Analysis of Casing Arrangements

program,

for Interfacing With Ofr.Base Combustor

Analysis of both the concentric and separate

PROJECT DESCRIPTION

piping between the combustion turbine and the

bed concepts to determine advantagesand

This project has been broken down as shown

disadvantages. This task will include a scoping

in the Work Breakdown Structure(WBS) in

stress analysis and a flow/pressure drop analysis.

Figure 1. Each of these tasks were further

broken down to give them visibility and track

their progress. Each is described below:

Task 12.4 Analysis of Turbine Systems

Modifications

Task 12.1 Analysis of Turbine and Plant

The subtasks associated with this effort

Performance

include:

This task will evaluate engine performance

• control system- scope the control

for the DMEC-1 requirementsas well as other

system requirementsto operatein the

applications. The following variables will be

PFB mode considering overspeed

taken into consideration duringthis analysis:

protection of the machinery

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CONCEPTUALDESIGN OF A GAS TURBINE FOR

PFBC APPUCATION

WORK BREAKDOWNSTRUCTURE

1 I

!

,,,

ARRANGEMENTSFOR

TURBINE AND PLANT INTERFACINGWITH START-UPCOMBUSTION PERFORMANCE OFF-BASECOMBUSTOR SYSTEM

I OFrTIMUM I

BLADIIO AND COOLINGI TURBINESYSTEM INTERCONNECTING AR_ ,,I MOOFICATIONS PIPING SYSTEM

Figure 1. Work Breakdown Structure

• startupsystem - scope requirementsto

Task 12.6 Design of Interconnecting Piping

obtain self- sustainingspeed to provide

System

compressorair to the PFBC. Scope level

This taskeffort is based on the piping effort

of changes to presenteconopac fuel skid

that has been done on the DMEC-1 CCT-rII

program. We will review line sizes, thermal

• define both the mechanical and thermal

requirementsand mechanical designs as they

requirements of the inlet and exhaust

relate to the combustion turbine.

system - scope the key requirements

considering the proposed heating/cooling

RESULTS

coils in the inlet systera for DMEC-1.

Efforts to date have been in the areaof

performance (Task 12.1). Table 1 gives a matrix

of the variousconditions that have been

Task 12.5 Design of Start-Up Combustion

analyzed. In addition to this matrix, two

System

differentfuels were analyzed, the results of

which indicate that an increase in moisture in

Define the pressurevessel arrangementand

the flue gas results in more net power out of the

"

combustorconfigurationfor the start-up

turbine.

combustor system. Verify the numberof stamap

Table 2 gives the results of the changes in

combustorsrequiredfor DMEC-1. Key

ambienttemperaturewith the low flow

elements will include:

compressor (17 stages) with a burneroutlet

temperature of 1600° and 1950°F. Only three

• Layout of conceptual design

ambients were consideredbecause DMEC-1 will

• Combustorrequirements

have provisions to limit the inlet air ambient

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Table 3 gives the results of a change in

compressor (standard 251B 12). Burner outlet

pressure drop across the PFBC system with the

temperatures of 1600°, 1950° and 2300°F were

low flow compressor. Three different pressure

considered.

drops were taken into consideration.

Table 5 gives the results from the analysis of

Table 4 gives results of the change in

three different pressure drops across the PFBC

ambient temperature with the high flow

system.

Table 1. Matrix of Operating Conditions

Nominal Burner Outlet Temi_ramm

Compremor InM

Flow (Nominal) 1600°F 19S0°F D00°F

220 lh/sec Ambient Pressure- 14.3 psia Ambient Pressure- 14.3 psia

(17 stage Relative Humidity- 65% Relative Humidity - 65%

compcesscx) Cooling Air 8% of Compressor Flow Cooling Air 12% of Congxe_or Flow

370l_w,c Ambient Pressure- 14.3 psia Ambient Pressure- 14.3 psi& AmbientPressure- 14.3 psia

(19 stage Relative Humidity- 65% Relative Humidity - 65% Relative Humidity - 65%

co_or) Cooling Air 10% of CompressorFlow Cooling Air 15.5% of _or Flow Cooling Air 18% of Comp_._ar Flo_

Table 2. Effect oi' Change in Ambient Temperature With Low Flow Compressor Inlet

i

1600°F BOT

1950°F BOT

iiii

Ambient Temperature

(°F)

59

80

90

59

80

90 Ambient Pressure

(psia)

14.3

14.3 Relative Humidity

(%)

65

65 Net Power Output

(kW)

20,250

17,870

16,780

27,980

25,200

23,920

Compressor Inlet Flow

(Ibis)

229

219

214

229

219

214 Exhaust Flow

(Ibis)

265

253

246

252

246 Exhaust Temperature

(°F)

801

815

821 1,000

1,013

1,019

PFBC Pressure Drop

(psi)

18.85

18.85 Scroll Pressure Drop

(psi)

1.84

1.68

1.62

1.81

1.73

1.70 Table 3. Effect of Change in PFBC Pressure Drop With Low Flow Compressor Inlet

1600°F BOT

1950°F BOT

PFBC Pressure Drop

(bars)

0.5

0.9

1.3

0.5

0.9

1.3 Ambient Temperature

(°F)

59

59 Ambient Pressure

(psia)

14.3

14.3 Relative Humidity

(%)

65

65 Net Power Output

(kW)

21,240

20,700

20,250

29,040

28,510

27,980

Compressor Inlet Flow

(Ibis)

229

229 Exhaust Flow

(Ibis)

265

264

264 Exhaust Temperature

(OF)

800

801

997

998 1,000

Scroll Pressure Drop

(psi)

1.67

1.74

1.84

1.66

1.74

1.81

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Table 4. Effect of Change in Ambient Temperature With High Flow Compressor Inlet

1600°F BOT

Ambient Temperature (°F) 32 59 80 90

Ambient Pressure (psia) 14.3 14.3 14.3 14.3

Relative Humidity (%) 65 65 65 65

Net Power Output (kW) 40,735 36,335 32,685 30,885

Compressor Inlet Flow (Ibis) 384 364 348 341

Exhaust Flow (Ibis) 444 420 401 392

Exhaust Temperature (°F) 720 734 746 752

PFBC Pressure Drop (psi) 18.85 18.85 18.85 18.85

Scroll Pressure Drop (psi) 2.29 2.17 2.08 2.05

1950"F BOT

Ambient Temperature (°F) 32 59 80 90

Ambient Pressure (psia) 14.3 14.3 14.3 14.3

Compressor Inlet Flow (Ibis) 384 364 348 341

Exhaust Temperature (*F) 885 900 912 917

PFBC Pressure Drop (psi) 18.85 18.85 18.85 18.85

23000F BOT

Ambient Temperature (°F) 32 59 80 90

Ambient Pressure (psia) 14.3 14.3 14.3 14.3

Compressor Inlet Flow (Ibis) 384 364 .... 347 338

Exhaust Temperature (*F) 1,053 1,067 1,080 1,085

PFBC Pressure Drop (psi) 18.85 18.85 18.85 18.85

Table 5. Effect of Change in PFBC Pressure Drop With High Flow Compressor Inlet

1600°F BOT 1950°F Bor 2300°F BOT

PFBC Pressure Drop (bars) 0.5 0.9 1.3 0.5 0.9 1.3 0.5 0.9 1.3

Ambient Temperature (°F) 59 59 59 59 59 59 59 59 59

Ambient Pressure (psia) 14.3 14.3 14.3 14.3 14.3 14.3 14.3 14.3 14.3

Relative Humidity (%) 65 65 65 65 65 65 65 65 65

Net Power Output (kW) 38,030 37,210 36,335 50,450 49,590 48,705 62,150 61,160 60,130

CompressorInlet Flow (Ibis) 364 364 364 364 364 364 364 364 364

ExhaustTemperature (°F) 733 734 734 899 899 900 1,065 1,066 1,067

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To date, three basic designs of the Also, the existing compressor/combustor

combustor/compressor cylinder have been cylinder is an integral part of the engine support

considered, based on a toroidal manifold (donut) concept. The turbine inlet scroll would have to

to distribute the hot gases returning from the be lined with a cooled inner shell for the 1600°F

PFBC. Concept 1, shown in Figure 2, has PFBC gas, with a heavier outer shell used for

separate inlet/outlet piping for compressor structural support.

discharge and hot gases returning from the

PFBC, while Concept 2, shown in Figure 3, uses The separate inlet/outlet design (Concept 1)

eccentric inlet/outlet piping. Both 1 and 2 use uses the same toroidal manifold to distribute

off-engine start-up combustors. Concept 3, returning hot gases from the PFBC, but

shown in Figure 4, is a variation on Concept 1 substitutes two smaller diameter casing

with on-engine start-up combustors, penetrations for each large penetration required

by the eccentric in/out arrangement. Since there

CONCEPT 1 is no inlet scroll, both manifolds are shown with

screens to distribute flow uniformly to each

A concept using separate compressor outlet transition duct. These screens are optional, and

and turbine inlet scrolls, which would give better the turbine could be operated with an uneven

circumferential flow distribution, was rejected flow pattern if the l/rev excitation were

because of the large amount of ttmling required, tolerable.

1600° F

1600°F

800°F

CONCEPT 1 - SEPARATE PIPES

EXTERNAL STAR_P AND PFBC COMBUSTORS

Figure 2.

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1600°F 1600°F Figure 3. 1600°F 800°F I

i

t

STARTUPCOMBUSTORII 1600°F i

CONCEPT 3 - SEPARATE PIPE8 ANO EXTERNAL PFBC COMBUSTORS

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J.

In a separate inlet/outlet configuration, two resulting design would be more susceptible to

inlet pipes and two outlet pipes are required to cyclic thermal cracking.

accommodate the airflow. The advantages of

separate inlet and outlet pipes are that the Both toroidal manifold designs may be

penetrations are smaller, and they can be refitted to the 251B 12 design with some effort,

staggered to preserve the strength of the casing and both use standard combustor section

transition ducts. The flow pattern might be

and allow access to flanges. The outlet pipes are

placed further downstream, which improves the improved by replacing the eight individual

outlet flow somewhat. The outlet pipe would be transition ducts with a single annular transition

flanged close to the casing, so that removing a duct, but this would make supporting the

short section of piping would provide manifold more difficult, and would require the

maintenance access to the toriodal manifold and compressor discharge air to circulate around the

the transition ducts, manifold.

CONCEPT 2 CONCEPT 3

The toroidal manifold design with eccentric In Concept 3, the existing 251B 12 combustor

inlet and outlet piping (Concept 2) is essentially baskets are used as startup combustors. The

the concentric inlet/outlet design which has been mixing, cooling, and diffusion holes in the

combustors are sized for the design point airflow

under consideration, except that the pipe of the 251B 12, and should not impose a large

centerlines are now offset to allow a larger outlet performance penalty when the engine is operated

pipe, the transition liners now have a flex plate in the PFBC combustion mode. This concept

centerline support also affords several opportunities for variations

In the eccentric in/o'.,_ arrangement, the in the thermodynamic cycle. In the first zone, maximum inlet pipe diameter of the outlet pipe most of the compressor discharge air is routed to

is limited by the length of the compressor/ the PFBC, with the remainder serving to cool

combustor casing. Two sets of eccentric pipes the space between the toroidal shell and the

are required to accommodate the airflow with compressor/combustor cylinder wall. The flex

acceptable losses. A configuration with one set plat provides the structural.support for the

in the base half and one set in the cover half toroidal shell. In this concept, the startup

would give better flow distribution and structural combustors could also be used as topping

support, whereas having both sets of pipe in combustors. The cooling air also provides

either the base or cover half would be less preheated, clean air for primary zone

expensive to build and maintain. Having both combustion.

sets of pipe in the base half would allow the

cover to be lifted without interference, but _{A recommendation} _{on which is the best}

would require extensive rerouting of existing

piping and redesign of the current engine concept has not yet been made.

support structure. On the other hand, if both sets

were placed in the cover half, the weight of the

cover to be lifted would increase substantially, Future Work

and disconnecting the piping would be added to

the maintenance routine. With both sets La As indicated in the schedule the project is

either half, the piping might h_,.veto be angled to approximately fifty percent complete. The

allow flange access. There is a potential creep remaining work is to complete ali tasks and

buckling problem with the hot inlet pipe, since submit the final report by April 1993 so that the

there is a net external AP of 20 psi. Although DMEC-1 program can be favorably impacted by

this could be overcome with ring stiffeners, the this effort.

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