MARC Steam Turbines The Modular Steam Turbine Generation

MARC ® 

Steam Turbines 

The Modular Steam Turbine Generation 

Engineering the Future – since 1758. 

MAN Turbo

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Originating from the Blohm+Voss shipyard, MAN Turbo AG Hamburg today combines 

the experience of a traditional company with state-of-the-art technology.

The first steam turbines under the name 

of Blohm+Voss were manufactured in 

1907, initially for ships built in the shipyard 

and subsequently for electric power 

generation. Since 1952 the company 

concentrated on developing and manufacturing 

industrial steam turbines. The 

list of worldwide references encompasses 

more than 2,000 turbo generators. 

A wide range of renowned companies 

and utilities use our turbines, mainly in 

Industrial power plants 

Cogeneration plants 

Waste incineration plants 

Biomass power plants 

Combined Cycle plants 

Our modern manufacturing facilities in 

Hamburg are equipped with machine 

tools of high performance and cover a 

floor area of more than 10,000 m2 . The 

quality management system is certified 

to DIN EN ISO 9001. Centrally situated 

in the free-port of Hamburg, MAN Turbo 

offers ideal transport links, enabling 

even large components to be transported 

with ease. 

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The concept 

The customers’ demand on durability, efficiency and economy has always had 

top priority for the development of BVI steam turbines. The result of our permanent 

development is a solution that sets new standards: The MARC (Modular 

ARrangement Concept) turbine series has proven its high quality throughout 

more than 100 installations since its market introduction in 1998. This modular 

turbine concept allows a flexible arrangement of the auxiliary components and 

enables the overall assembly to be set up in line with individual requirements. 

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The turbo generator unit comprises the 

following modules: 

Steam turbine 

Gearbox/generator unit 

LP lubricating oil system 

HP control oil system 

Control cabinet 

The lubricating oil module, control oil 

module and the control cabinet can be 

individually arranged around the unit. 

MARC Turbines 

Modular ARangement Concept 

MARC 1 MARC 2 

MARC 4 



Electric power 

up to 3 MW 

Max. flange diameter 

Live steam: 125 

Exhaust: 700 

Max. live steam conditions 

30 bar(a) / 480°C 

up to 15,000 1/min 


up to 12 MW 



Exhaust: 1,200 


90 bar(a) / 520°C 

up to 12,000 1/min 


up to 22 MW 





120 bar(a) / 520°C 

up to 10,000 1/min 

Benefits of the modular concept: 

Proven turbine design with robust 

technology and high availability 

Space-saving, low-noise epicyclic 

gear generator unit (up to 25 MW) 

High level of efficiency thanks to 

optimised turbine design and use of 

epicyclic gearing 

Use of proven system modules for 

lubricating oil and control oil 

Compact control cabinet as blackbox 

for connection via bus system 

to the central control system 

Low investment costs 


up to 35 MW 





120 bar(a) / 530°C 

up to 8,000 1/min 


up to 50 MW 





120 bar(a) / 530°C 

up to 6,000 1/min 

Five different turbine sizes cover a performance 

range from 1.5 MW to 50 MW. 

The MARC production programme 

includes backpressure, heating and 

condensing turbines that can also be 

fitted with extraction and bleed ports. 

Explanation of type codes: 

MARC x - A B C 

x–Code for turbine size 

A– Code for turbine type 

C: Condensing 

B: Backpressure 

H: Heating 

B– Number of controlled extractions 

C– Number of bleed ports 

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Turbine type B: 

Backpressure 

Backpressure turbines are used as generator 

drive units in combined heat and 

power plants and for on-site electricity 

generation of industrial facilities. They 

are also used in cogeneration applications. 

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Turbine type C: 

Condensing 

The areas of application for condensation 

turbines range from turbo generators 

for industrial power plants and 

waste incineration systems through to 

biomass facilities. 

The extraction steam is typically used 

for heating, production purposes and 

feed water prewarming. To achieve optimum 

part-load efficiency, the LP part 

can also provided with a nozzle group 

control. 

Turbine type H: 

Heating 

The typical application is electricity 

and heat generation. The special feature 

of this turbine type is the double-flow 

exhaust for connect-ing a two stage 

heating system. This design provides 

the most efficient way of electricity and 

heat production throughout the year.

The new MARC 1 

The success formula of the MARC 2 has been transferred to a new MARC model in the power 

range of 1.5 - 3 MW. Built on the design principles of proven turbines and the positive operational 

experience gained, the new MARC 1 turbo generator has been developed specifically for 

use in the smaller segment of biomass applications. 

With the MARC concept developed in 

the mid-1990’s, MAN Turbo has successfully 

established itself in the biomass 

power plant market sector from 

4 - 20 MW electrical output. MAN Turbo’s 

operational experience with steam tur- 

bines previously supplied for biomass 

power plants provides compelling evidence 

of the economic efficiency and 

operational reliability of this concept. 

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Turbine module 

In industrial turbines, part of the steam 

often is extracted for production purposes, 

heating steam systems or generative 

feed water heating. In that case, 

in addition to several bleedings, two 

controlled extractions can also be provided. 

The MARC concept allows an 

individual and optimized design of the 

different turbine elements, according to 

specific requirements, such as the pressure 

level and the extraction steam 

quantity. 

Depending on the live steam conditions 

and the specified operation mode, either 

a nozzle group control with or without 

bypass or a throttle control may be se- 

8 

lected. The control stage, either single 

or two-row type, and the number of reaction 

stages are especially adapted to 

the specific requirements. For all reaction 

stages the low-loss round-head 

profile is used. 

The HP blades are provided with milled 

shrouds, whereas the last blade rows 

are mostly designed with conically twisted 

blades, the blade ends of which 

being tip-thinned on one side.The rotor 

blades of the last rows are grouped by 

means of damping and bind-ing wires in 

conformity with the results of vibration 

calculations. Due to the small flow 

volume, steam admission of the im- 

pulse wheel is only necessary in the 

upper casing half, how-ever, the lower 

half can also be utilized, if required. In 

that case, a bypass leads to the lower 

nozzle group. 

The exhaust casing is a welded construction 

and may either be fitted facing 

upward or downward, depending on 

the site conditions. MARC steam turbines 

have been designed for highest 

operating security and utmost reliability. 

As the highest thermal impact on the 

steam carrying parts occurs at load 

changes, the casing, guide blade carrier 

and inner casing have been developed 

for a high thermal elasticity.

The following design features apply 

for all turbine types: 

multi-stage reaction design 

maximum symmetry of the upper 

and lower casings 

symmetrical temperature distribution 

at the circumference in all crosssections 

under all load conditions 

single-piece forged rotor 

labyrinth sealing glands between 

rotor and casing 

split tilting pad sleeve bearings 

self-aligning axial bearing, for doublesided 

loading 

nozzle group control 

guide blade carrier 

Turbine rotors 

The reaction turbines are supplied with 

a drum-type rotor. The turbine rotors, 

the balance piston and the impulse 

wheel disc as well as the subsequent 

drum parts are solid forging of high temperature 

material.The rotor design is 

based on modern calculation methods 

to meet the highest demands regarding 

smooth and resonant-free operation. 

The bladed rotors are statically and dynamically 

bal-anced at operating speed 

in a modern high-speed vacuum balancing 

plant, in a way that the shaft vibrations 

over the whole speed range 

are considerably below ISO10816 permitted 

values. 

Bearings 

The radial bearings are of multiface 

sleeve or tilting pad type. A stable rotor 

position is maintained by hydrodynamical 

oil wedges, equally spaced on the 

circumference.The axial forces resulting 

from pressure differences in the blading 

are mainly absorbed by the balance 

piston. A double-sided segmental axial 

bearing absorbs the residual thrust and 

the coupling forces. 

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Bearing Pedestals 

The bearings are located in two bearing 

pedestals on which the turbine casing 

rests by means of brackets on the level 

of the horizontal joint. The exhaust connection 

of condensing turbines rests on 

lateral supports on the level of the horizontal 

joint. Due to this form of arrangement, 

the position of the rotor to the 

casing and thus, the radial blade clearance 

remain virtually constant under all 

load and temperature conditions. 

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Labyrinth Sealing Glands 

The steam sealing between the turbine 

rotor and the casing located at the 

casing’s ends as well as at the balance 

piston is a labyrinth sealing type. The 

sealing strips of high-temperature material 

are caulked into the rotor. 

Blading 

In the blading, consisting of control 

stage and reaction part, the potential 

energy of the high-pressure steam is 

converted into mechanical energy. 

Control Stage 

Due to partial admission, a high degree 

of dynamical tension occurs in the 

blades of the control stage. This tension 

is reduced by grouping the blades in the 

shrouding.Highly loaded control stages 

are designed with blade triplets, meaning 

that three blades having one root 

together are machined from one workpiece.

Reaction Part 

The multi-stage reaction blading ensures 

utmost reliability and economy due to 

high mechanical and thermal 

strengthen both guide blades and 

rotor blades to withstand operating 

stress 

a large sectional modulus to avoid 

vibrations. 

low flow losses in the blading covering 

a wide operating range. 

The guide and rotor blades have the 

same profile. It was theoretically and 

experimentally tested during its development. 

Hereby, the characteristics of 

the profile, depending on the cascade 

arrangement and the entry angles, were 

determined by measurements in a plane 

wind tunnel. 

A characteristic feature of partload operation 

is the entry angle deviating from 

the normal line of flow. The impact-free 

entry angle range is very large and ensures 

a high part load efficiency at operating 

conditions different from those of 

rated load. 

The clearance and rim losses of backpressure 

turbines and high-pressure 

parts of condensing turbines are reduced 

to a minimum by using shrouds. 

The blade with root and shroud is 

machined from one piece. After blading 

the rotor, the shrouding is machined to 

its form. Regarding stages with a low 

clearance loss factor, the blade tips are 

provided with a one-sided thinning. 

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Control mechanism 

The steam control valves of MARC turbines 

are of a diffuser type. Small valve 

dimensions allow a vast number of valves 

and nozzle groups. Consequently, 

the throttling losses are kept low also at 

part load. The cone form of the valve 

has been optimized regarding the flow. 

Valve spindles, valve cone and valve 

bar consist of heat-resistant steel with 

hardened, wear-resistant surface. The 

hardening is effected via a plasmahardening 

process. 

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Due to the small valve dimensions, the 

steam control valves can be actuated 

directly. This so-called group drive is 

a compact and reliable solution. The 

actuator is a single acting hydraulic 

cylinder which is fed by the control oil 

system at an oil pressure of 160 bar. 

On turbine tripping or full-load disconnection 

the valves are closed by 

the pre-loaded spring, thus, protecting 

the turbine plant at malfunctions. If the 

pressure in the control oil system decreases, 

both the control valves and the 

tripping devices will be closed automa- 

tically, as they act on the same principle 

(single-acting hydraulic piston against 

pre-loaded spring). This means double 

security for the turbine and the steam 

system. A lever system for parallel motion 

of both valve spindles precisely 

transmits changes of the controller output 

onto the valve bar and – depending 

on the valve lift – on one or more valve 

cones. The moving parts are made of 

non-corrosive and maintenance-free 

self-lubricating material. The valve 

spindles are sealed by maintenancefree, 

pre-compressed graphite laminated 

glands, and reinforced carbon 

guide bushes.

Gearbox/Generator module 

Gearbox and generator are installed as 

one compact unit. For the MARC 2 and 

the MARC 4, generally an epicyclic 

gearbox is used which is flanged directly 

to the generator. For the types MARC 6 

and MARC 8 either an epicyclic or a 

helical gearbox is used, depending on 

power and speed. 

The application of epicyclic gearboxes 

bear the following advantages: 

The offset usually caused by a helical 

gearbox is avoided, which greatly facilitates 

the alignment. Moreover, one 

coupling and the high-speed gear 

bearing are omitted which improves 

the total efficiency. 

13

Lubrication oil module 

The lubrication oil system* is a compact 

module designed as a low-pressure oil 

system for turbine, gearbox and generator, 

consisting of: 

14 

Lubrication oil system Turbine Gearbox and 

generator 

complete set of 2 main oil pumps 

emergency oil pump with DC motor 

oil cooler 

redundant oil filter 

oil mist fan 

temperature control valve 

pressure control valve 

* For MARC1: Combined lubrication 

and control oil system. 

Diagram of the 

lubrication oil system 

1 Turbine 

2 Turning gear 

3 Extraction 

4 Exhaust steam 

5 LP control valvel 

6 HP control valve 

7 Trip valve 

8 Gearbox 

9 Generator 

10 Oil tank 

11 Main oil pump 1 

12 Main oil pump 2 

13 Emergency oil pump 

14 Oil cooler with cooling 

water connections 

15 Oil filter 

16 Oil mist fan

Control oil module 

Control oil system Turbine Gearbox and 

generator 

The control oil system is a compact 

module. The main components are: 

oil tank designed as base frame 

main oil pump with AC motor 

pressure tank 

redundant oil filter 

bypass pump 

oil cooler 

measuring and control system 

Apart from the control valves, the system 

also feeds the live steam trip valve and, if 

necessary, the extraction-trip valves and 

control devices in the extraction with a 

system pressure of 160 bar, commonly 

used for hydraulic systems. 

Diagram of the 

control oil system 

1 Turbine 

2 Gearbox 

3 Turning gear 

4 Generator 

5 LP control valve 

6 HP control valve 

7 HP trip valve 

8 Extraction non-return 

flap 

9 Turbine governor 

10 Generator cooler 

11 Extraction 

12 Exhaust steam 

13 Oil tank 

14 Circulation pump 

15 Control oil pump 

16 Control oil cooler 

17 Pressure tank 

15

Measuring and Control System 

16 

Ethernet 

or 

Profibus 

Hardware 

Data storage 

Central Processing Unit 

(CPU) 

Vibration 

monitoring 

Overspeed 

protection 

Generator 

protection 

Voltage 

controller 

cos 

controller 


The turbo set control cabinet is a compact 

unit that can be arranged flexibly 

around the turbine unit. All control 

functions and protection of the turbine 

and generator are integrated in a single 

control box with a user interface on the 

front. This saves space and ensures minimal 

installation and commissioning 

time. 

All desired signals can be sent via a 

databus (e.g. Ethernet or Profibus) to a 

host control system, and operational 

commands and setpoint values can be 

received from there. 

Function 

Turbine open-loop 

controller 

Turbine closed-loop 

controller 

Turbine protection 

and monitoring 

Generator 

protection 

Generator 

controller 

Control system 

In order to maintain flexibility when meeting 

the varied process requirements, 

the turbine control system is implemented 

in the modern programmable logic 

control (PLC) system S7-400. The comprehensive 

range of modules enables 

flexible and user-friendly handling of a 

wide range of communication options 

to other systems and problem-free 

expansion, should additional tasks be 

required. Startup, shutdown and operation 

of the entire turbine unit are completely 

automated in the control system, 

with ease of use being one of its key 

features. 

Based on many years of experience in 

the field of turbo generator operation, 

we have developed a digital steam turbine 

controller. The inte-gration of this 

controller in the existing control system 

hardware enables a contin-uous control 

concept and optimal integration of the 

controller without additional interfaces. 

The steam turbine controller is a powerful 

and flexible device. Speed, output, 

pressure and temperature are optimally 

controlled and critical variables are 

limited. All control modes are seamlessly 

integrated.


Field 

ISDN 

Router 

External 

Trips 

Turbine 

trip valve 

Control room 

Measurement 

transducer 

Ethernet or Profibus 

MP270-B SIMATIC CPU 414 - DP I/O Rack 

Data Logger 

PC 

Turbine 

Operation 

The turbo generator can be operated 

either via a central control system or locally, 

directly via the operator interface 

on the control panel. In automatic mode 

only the turbine start/stop commands 

and specification of the setpoint values 

are required. All operating modes and 

fault messages are displayed locally and 

supplied to the control system via a bus 

system. In manual mode, local control 

of the auxiliary modules and components 

is possible. 

Pressure 

Temperature 

Vibrations 

Hardwired 

Profibus 

PC 

Generator 

protection 

Limit switch 

Control box 

Overspeed 

protection 

Hardwired 

Safety 

All turbine units are provided with extensive 

safety equipment that safely shuts 

down the steam turbine and generator 

when critical conditions are reached. 

The classification of safety criteria is in 

accordance with IEC 61508. Measurement 

systems, trip and alarm criteria are 

specified in such a way that an optimal 

balance between machinery protection 

and availability is achieved. If desired, 

the design also enables unattended 

24-hr operation. 

Lubrication Oil 

Control Oil 

Voltage 

controller 

Emergency 

switch-off 

Condenser 

Low voltage 

switchgear 

Mean voltage 

switchgear 

Hardwired 

Remote access 

A datalogger with ISDN interface enables 

remote support for your operating 

personnel: Important operating data is 

saved to a datalogger and can be analysed 

by our Service Team, while our 

service engineers have direct access to 

the control system and control panel. 

This enables us to provide you with 

quick and cost-effective support. 

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Quality Assurance 

The most important principle of turbine 

manufacture is to ensure high quality 

standards for all components. The 

turbines are subjected to the following 

checks during the manufacturing 

process. 

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Material inspections 

Castings inspection 

Production inspection 

Assembly inspection 

Continuous quality control is ensured 

by the ISO 9001 quality management 

system.The turbine and baseframe are 

erected and the internal piping is installed 

on the assembly bed. The gearing/generator 

modular unit is assembled 

at the generator manufacturer and 

subjected to a functional check. As with 

the other modules, both oil modules are 

tested at the manufacturer prior to their 

installation adjacent to the turbine on 

site. 

In order to meet the requirements for 

quiet running, operational safety and 

high availability of the steam turbines, 

each turbine rotor is subjected to highspeed 

dynamic balancing and spin 

testing in a vacuum spin test facility. 

After this acceptance test the rotor can 

be installed.

Service 

Our experienced Turbine Service 

Department ensures the professional 

installation of the supplied turbine unit, 

including commissioning and trial operation. 

The operating personnel concurrently 

receive training as required. 

MAN Turbo provides person-al consultancy 

and optimum support for service 

and repair work as well as for retrofitting. 

Maintenance and revisions are 

coordinated between our service 

department and the customer. Our 

experienced service staff is available 

night and day to assure the recommissioning 

of the plant. 

19

MAN Turbo AG 

Steinbrinkstrasse 1 

46145 Oberhausen/Germany 

Phone +49. 208. 6 92-01 

Fax +49. 208. 6 92-20 19 

www.manturbo.com 

MAN Turbo – a member of the MAN Group 

In the interests of technical progress, 

subject to change without notice. 

Printed in Germany. December 2008 

Turbo 1002 e 1208 1.5 ba

MARC Steam Turbines The Modular Steam Turbine Generation

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