CRANES FOR THERMAL POWER PLANT.#3

The picture shows the erection of a Super critical unit steam generator is under progress. Cluster of crane is available for

erection. 120MT Fushun and 250 MT Kobelco are seen on the pictures doing erection of the structural member of the steam generator. Excavated area is the area of ESP . One more crane is doing some other job. In addition to the above crane a 600MT/1200MT crane has to be mobilised in the same area. All the cranes will work simultaneously in steam Generator. All three cranes will have their own angle of rotation and area . If their erection material is not identified

before it will certainly lead to confusion and may cause stoppage of on crane to give place for other crane. Also it is to been seen that very less space is available for crane operation. Therefore all the cranes boom length are to be decided before hand and boom extension and reduction  to

done as per plan only. 

The crane shown in the picture is liebeherr 150T tyre mounted all terrain crane with telescopic boom. This type of crane is best suited for erection of structure , ducts , motors , ID fan etc.

IT is easy to operates can reach far by sitting in one place. However the base or land should be plane and can carry the load of the crane. Only

difficulty of such crane is that it can not move with load or with counterweight. Counterweight 

is to be carried  separately . The advantage of this crane more than disadvantage as it can operate in comparatively less  space and boom

extension and reduction not necessary. Best suited for the wide variation of load in compact area.

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CRANES FOR THERMAL POWER PLANT # 2

The picture given in the left of this page is the picture of 1200MT crawler crane used for the erection of steam generator of 660MW . It is to be noticed that the arrangement of counter weight. Counter weight sometimes kept in a extra trolley to balance the load lifting capacity. Choice of high capacity crane for a project is to be done very carefully after considering  all aspect of erection requirement.

In earlier days in India high capacity crane requirement was not there as the unit size was small. Now a days unit size has gone up to 1000MW and above the requirement of high capacity crane is must. Erectors generally hires it from market. There are few agencies available in the market to supply it. However cost of hiring depends on demand in the market. Therefore choice is to be done carefully so that the crane can be used maximum time . The overall duration is to be minimum. For such high capacity crane requires 30 to

40 trailers of minimum 20 MT capacity to transport from its origin to destination. Beside 20 MT capacity trailer we may require 40 MT or above low bed trailer also. It will advisable to discuss the

logistic with the crane supplier. 

To decide the crane type and capacity following aspect to kept in mind.

a. Jobs to be executed by the crane i.e for Steam Generator , ceiling girders erection , WB erections,

column erections , roof structure erections , lift column top tier erection etc.

b. Listing down the jobs , weight and height and also the angle from which erection is to be done.

c. Position of the crane whether it is indie the cavity or outside the cavity . If we position the outside

the cavity then crane capacity will be much higher than inside capacity. Exception is if we use tower

crane.

d.  Type of crawler and size of crawler. 

e.  Overall GA of the crane is required to position the crane.

f. Type of boom required i. Main boom, Jib Boom ( fixed jib or laughing jib , jewellery jib etc ) 

g. It is to be plan in advance that number of times boom needs to changed for work.

This type of high capacity crane requires huge space for assembly and to place in position. It is to be 

appreciated to assemble such crane we require at least 150 mts length space and around 8 to 10 Mtr

width is required for boom assembly. Along the assemble there should be place for auxiliary cranes to run to hold boom in position. It is therefore kept in mind that such place is available in the beginning of the project. As we go along with erection such places will not be available near site. Therefore maximum one or two occasion to be kept for boom configuration changing beside dismantling. Such

crane is always advisable to erect very near the actual site of erection. Otherwise there will be enormous  problem  to  transport them with 140 mt boom height to  site. Some of the crane demands 

road within half a degree of undulation otherwise the  crane will be stopped by its protection. There are three to four companies like Manitowac , Demag , Lieberhrr cranes are very good and well protected by their own mechanism . It is learnt that chinese companies are also making high capacity crane. Beside above issues there are few issues about placement which will be elaborated during steam generator erection.

The picture given below is to draw attention to the bottom of the crawler the plate fabricated pieces on which the crawler are resting. Such type of arrangement are absolutely necessary for the high capacity crane . This will reduce the undulation problem and also crane will be on firm ground and this is necessary whenever we are going for critical load lifting.  Unfortunately such practices are very

rarely being followed in India until and unless it has been insisted. However benefit of the system is

will be seen during SG erection.                

CRANES IN USE FOR CONSTRUCTION OF THERMAL POWER STATION.

HYDRA CRANE

This is Hydra crane which are extensively use in construction site. The crane is Tyre mounted and can move quickly one place to another  place quickly without any load. It can carry its

lifting tackles like sling , D-shakle etc . Hooks

are kept in fixed position at different location of boom indicating lifting capacity of the hook. The boom can be extended to increase the reach of the crane . Some times an extended piece has been fitted in front of extended boom  to further increase the reach. However the capacity of the crane is reduced to less than a Ton. The crane can move slowly with load hanging on the hook. It can move left and right

with the help of power cylinder fitted at the bottom of the frame. Boom up down can be achieved by a power cylinder. The crane is totally hydraulically operated. Operator console is having lever Type arrangements. The crane move in muddy undulated road .

18T/25T/40T/50T/ 75T/100T/120T/150T/250T/600T/1200 T  crawler mounted crane :

The above picture is a new generation TATA make 100MT crawler crane. (KH 500) . All the crawler

crane listed above are having same feature in looks. Differences will be on lattice boom structure size,

material , configuration etc. Crane will have one basic boom and other additional booms as per capacity . Fitting of booms additional  should be done as per sequence mentioned in the crane manual

to achieve desired output safely. This is true for high capacity crane above 75 MT capacity Every crane manufacturer gives all the information in their maintenance manual. 

to be continued../

CONSTRUCTION EQUIPMENT USED IN THRMAL POWER STATION

We will now discuss about the resources requirement about construction of thermal Power Plant  (coal  based ).

Thermal Power Construction Job can be broadly  divided to following categories .

A. Construction Job - Mainly civil work in and around the thermal Power Stations .

B. Structural fabrication job for powerhouse and other buildings which are having structural work.

C. Mechanical job of Equipment erection and commissioning.

D. Electrical job of Switch yard making ,cabling , commissioning etc.

E.Control and instrumentation work for equipment control.

For the above job lot of construction equipment are in use we will describe them as we describe them

as per their use.However we will wait for active participation from viewers from other countries to

comment on the equipment. My experience is based on Indian perception . However we have seen

the working methods of developed countries in INDIA.

CRANES :

Cranes are essential construction equipment which are used during construction phase extensively.

There are various types of cranes available in the market . The use of the will be determine  by its

requirement. Cranes can be crawler mounted , Tyre mounted and Truck mounted. Crane can be

Tower type also . Crane can be divided by their boom i.e lattice boom , telescopic boob  ,jib boom

combination of lattice boom with fixed jib , lattice boom with laughing jib etc. Tower crane is

entirely different type of crane having long Jib length and having fixed or movable counter weight.

At initial stage the  power house capacity was 30MW , 60MW and 120 MW.  In late seventies the

Power House capacity rises to 210MW/250MW/500MW and now 660 MW and finally we have

started 800 MW and future is 1000MW with ultra super critical technology . With this progress

cranes capacity from 100 MT has been increased to 1200 MT and above. For deployment of  high

capacity crane depends on Steam Generator Height , Mill bay structure , PH structure etc. The whole

process to be laid down during preparation of erection strategy of equipments. In general following

capacity and type of cranes are used in India for erection of Thermal Power station and readily

available in the market.

1.  Small tyre mounted multi head ( 11MT to 14MT) crane popularly known as Hydra . Generally

used as shifting of material at site , plant or equipment , unloading of material , erection of pipelines

and other at low height. Sometimes pulling or pushing immobile vehicles. Assembly of booms ,

sometime use in tandems for transporting oversize material with less wt. For a site size of 2x500MW/

2x660 MW site around 30 to 40 Hydra are required at peak erection time at project site. This versatile

machines are used every where.

COMMON KNOWLEDGE AS INPUT TO CONSTRUCTION MANPOWER

As on date we have acquired some knowledge about land requirement for a thermal power station .

Also we know what are the other factors and limits  for land requirements. We have also acquired

knowledge of Fuel use and environment boundaries. We assume that inputs  given to construction

manpower is adequate to understand the background of construction of thermal power station. Now

we will start discussing a few other things about construction which are commonly used or available

not only in power station but also in large process plant like oil and Gas, steel etc.

Before we start discussing the above a few more information which are miscellaneous  in nature but

extremely useful in long term decision making.

Siesmic Zone of the power plant :  In India Sismic Zone is diveided into five Zone i.e. from Zone I

to Zone V. This Zone division is according to less earthquake  prone area to  maximum  earthquake 

prone area. Siesmic Zone dictactes  the design aspect of Power plant regarding Civil and structural

and other mechanical items . Also decides the size of the plant which is economically viable at that

Zone. We understand such type of Zone divisions are available all over the world .

Wind velocity of the area. This is one more aspect which affects the design of power station of high

rise equipment like chimney , cooling towers ( IDCT and NDCT) , Steam Generation  unit , Power

house buiding , Part of coal handling plant like structure , gallery , stacker -reclaimer etc. Wind

velocity some time changes the erection methodlogy of the equipment.

Rain fall in the area :  The data is required to know for the pre-planning of the execution of the civil

work also construction of storm water drain on priority. Also this give an idea about how many days

are available for uninterupted work. More detail discussion will be initiated at later stage.

Topography of land and bearing capacity of the earth.  Knowledge of the same will help us to

make master network schedule of the project. Bearing capacity of earth will tell us whether piling

is necessary or not and the depth of plie. Also it will tell us whether rock is available just below the

soil  then rock cutting either blasting or some other method will be cessary. In both the cases more

time is required to consturct foundations of the plants .  Soil investigation will be carried out before

we start designing. Topography of the land helps to do the levelling economically and effectively.

.

Benchmarking of the area.   The area has to be bench accurately during first soil investigation.

Earlier days the bench marking used to be done by chain link survey , thedolite and dumpy level.

Benchmark was drawn from nearest bench mark by transfering them and the same was prone to

mistake. But now a days with help of total station accuracy of one second can be acheieved in bench

marking if need to transfer the same from long distance.

EQUIPMENT INSTALLED TO CURB POLLUTION IN THERMAL POWER PLANT

continued  from last blog.

Cooling Tower   :   Providing of cooling tower will reduce the thermal pollution and conservation of

                               fresh  water.

Ash Dyke and Ash Disposal System : Most of the modern Power stations are having wet and dry ash

system. Ash are extracted as per commitment and dispatched. lagoon with garlanding system are

being followed to changing over the ash slurry line  time to time. Ash particles settled in the lagoon

 ash and clear ash effluent was discharged.Dry ash  are being taken into bags or top opened 

container as per the arrangement envisaged during the initial stage.

Ash water recycling System.  This system was introduced a decade back and has been followed in

number of  power stations in India to reduce the intake of fresh water from other sources.

Utilisation of Dry ash :- Dry ash collected may be used for Ash bricks , For cement manufacturing

plant adjacent to thermal power plant or else where . Ash transported through  close railway wagon

Also use for road making , Mine filling , Road making etc. 

Effluent Treatment Plant :-  The objective of ETP ( Effluent Treatment Plant ) is to discharge lesser

cleaner effluent from thermal power plant. The effluent are primarily cleaned at their source and sent

ETP for treatment. ETP is designed to treat effluents from from WTP ( water treatment plant) , CHP (

coal Handling Plant) , CPU ( condensate Polishing Unit) etc.

With better awareness and management a few benefits are achieved.

- Reduction of land requirement  for main plant and ash disposal area.

- Capacity addition in old plants, within existing land.

- Reduction of water requirement in main plant and ash disposal area.

-Efficient utilisation of Fuel.

   

EQUIPMENT INSTALLED TO CURB POLLUTION AT THERMAL POWER STATION

We have discussed limits of Envoirment requirement briefly except two aspect about ash utilisation  and what are the steps are to be proposed to the authority for clearance.

For every Power plant whether it is in India or abroad running by coal will have policy of ash utilisation depend  upon the quantity it Generates . In India GOI laid down elaborate guidelines for utilisation of dry ash either from source or from ash pond. Readers those who wants to know that they

may send an e-mail to dguha1952@gmail.com . The same will be provided to them .

However we like to write few lines about the improvement proposals on environmental improvement.

Any organisation who are setting up a Thermal Power Station will have to define its environmental  policy in line with National Policy. It has to set up a wing to go through those policy and OHSAS 180001 etc. ( Any body can see OHSAS 180001 in Internet therefore such items are not explained here. 

While deciding the appropriate technology for its projects, a company  integrates many environmental provisions into the plant design. In order to ensure that company comply with all the stipulated environment norms, various state-of-the-art pollution control systems / devices have been installed to control air and water pollution.

1. Electrostatic Precipitators . Maximum efficiency available now a- days is 99.9% instead of 99.5%.

2. Tall fue Gas Stack            : 275 M as per norm to disperse the residual as at greater distance.

3.  Low NOx Burner             : To control NOx emission .

4.  Neutralising Pit              : provided with water treatment plant to control the PH before discharging

                                              to effluent treatment plant.

5.  Settling Pit (coal & oil)  : Waste coal dust , oil etc collected from CHP & FOHP  removed here

                                              before sending it to ETP ( effluent treatment plant). 

6. DE and DS  system         : DE ( Dust extraction ) and DS ( Dust Suppression) installed in CHP to

                   

                                              capture loose coal dust .

to be continued..........