Monday, September 26, 2011

Coal Handling Plant

Coal can be bought to the power plant via trucks or train or ship if power plant is located near sea.
The most common way to bring coal is by train.

Generally a railway track needs to be laid from the nearest railway station to the power plant. The train wagons are automatically unloaded using a wagon tippler mechanism and the unloaded coal is stored in an underground bunker. This coal is then conveyed to the crusher house using belt conveyor system. In the crusher house coal is crushed to around 25mm size. The crushed coal is then stored in coal stockyard using a mechanism called stacker-reclaimer. The coal is further conveyed to the ball mill via belt conveyor system. In the ball mill coal is pulverized to a powder form. This powder form is conveyed to the coal burners of the boiler using hot air which also dries the coal.

Generally speaking, about 0.5 T/hr of coal is required per MW unit size. So if you had a 200 MW unit, then 100 T/hr of coal would be required.

For 24 hours, you would need 2400 T of coal

One train carries appox 3000T. of coal. So 1 train of coal would be required to unloaded per day.

Wednesday, March 9, 2011

About Pipes - Part 2

ASME and ASTM have defined the dimensional standards and material standards respectively for all pipes used in process plants. These bodies publish various codes/standards so that engineers can select pipes suitable for their application based on these internationally accepeted standards.

Carbon Steel Pipe is the most common type of pipe and is mostly specified according to ASTM 106. Within the ASTM A106, carbon steel pipe is available in Grades A,B and C based on increasing tensile strength.

Galvanized Carbon Steel Pipe is mostly specified as per ASTM A53

Stainless Steel Pipe upto 200mm Nominal Bore is mostly specified as per ASTM A312. Within ASTM A312, eighteen different grades of stainless steel pipe are specified with grade 304L as the most commonly used grade in industry. Stainless Steel pipes above 200 Nominal Bore are specified as per ASTM A358

*In India its very difficult to obtain seamless pipes above 350 NB from any of the vendors

* ASTM - American Society for Testing and Materials
*ASME - American Society of Mechanical Engineers

Saturday, March 5, 2011

Weight of Pipe in terms of Kg per meter

The weight of pipe in terms of Kg per meter is = Diameter *Thickness * 16

For example a 10 inch pipe with 0.25 inch thickness has a weight of  = 10 *.25 * 16 = 40 kg per meter.

This calculation is only a thumbrule with very good accuracy. For actual billing, the weight of the pipe from pipe tables should be taken.

Calculating Electrode Consumption for Pipe Per Weld

Lets say we have a 12 inch pipeline which needs to be welded. 
Kg of Electrode Required per Weld = (Dia of Pipe/2) * 0.1 =  (12/2)* 0.1 = 0.6 kg

This is only a rough thumbrule calculation for calculating the quantity of electrode per weld.

Wednesday, March 2, 2011

Top Engineering Consultants in India

Some of the top engineering consultants in India are:
  • Tata Consultancy Engineers
  • Engineers India Ltd.
  • M.N Dastur Co. Ltd
  • Development Consultants Pvt. Ltd
  • J P Mukheerjee Consultants
  • Black and Veatch
  • Fitchner Consulting Engineers
  • Uhde India Pvt Ltd.
  • Sargent and Lundy
  • Doosan Engineering Consultants

Construction Photos of Essar Power Plant at Salaya, Gujarat

Recently i was very impressed with the professional management of Essar Power in managing a complex project such as the Salaya Power Plant at Gujarat. Here is a presentation from Essar Power from their website on status of construction.

This presentation has some great photos of power plant under construction from slide 28 onwards.


Sunday, February 13, 2011

Why Microsoft Project should not be used as a Project Monitoring Tool

At first glance, Microsoft Project appears as a very user friendly tool for project scheduling and monitoring. Infact most of the L2 schedules, I have seen seem to have been done in Microsoft Project.

After using Microsoft Project on my last 4 projects ( average project value around  Rs 30 crores), there seem to many major flaws in Microsoft Project software, namely

1. Percentage Complete for any Activity is defined as Actual Time Spent on Activity divided by the Original Duration of the Activity. This to me seems fundamentally flawed. If i had an activity whose Original Duration was 10 days, and i spent 8 days on the activity, then Microsoft Project will show that activity as 80% complete while in reality it maybe only 20% complete due to slow progress.
This is a fundamental limitation of the software and i have discussed this with many of the scheduling experts and no one seems to have a work around solution for this.

2. Microsoft Project gives crazy results when an activity is started out of sequence. For instance after completing the structure of a multi-story building I had planned in MSP to do the brickwork first on the ground floor and then on the first floor. Now due to some issues, in reality i started my brickwork on the first floor and then i would do the brickwork on the ground floor. When we update this in MSP, it still keeps showing the ground floor brickwork activity in the past and does not move the task as something we have to do in the future. As a result the entire shedule becomes distorted and unreliable.

Over the last year, i have also been using Primavera in parallel with Microsoft Project and i am very happy with Primavera's scheduling capablites. It does not seem to have any scheduling flaws and seems to be giving correct results.

Thursday, February 10, 2011

Type of Work at Construction Site

As a Site-in-charge, most of my time is spent upon:

1. Planning - involves studying of drawings and determing the resources required to complete the work
2. Overseeing actual construction work happening at site
3. Keeping track of material in the site store
4. Correspondence with client and Head Office
5. Making reports regarding site progress and making RA bills
6. Keeping the sub-contractor focussed on the job at hand

Wednesday, February 9, 2011

Ash Handling System in a Thermal Power Plant

Coal is burnt in the furnace to heat the boiler to produce steam. Burnt coal is called ash. Some part of the ash falls to the ground and is called bottom ash and the ligher ash particles fly in the air and are called fly ash.
There are different systems for dealing with bottom ash and fly ash.

Bottom Ash: The bottom ash falls through the furnace grating and is collected in a hopper. Its then grinded and crushed to produce find powder ash. The powder ash is then mixed with water to produce ash slurry.
The ash slurry is then pumped to an open pond called the ash dyke.

Fly Ash: The flue gas exits the furnace and is finally disposed off through the chimney. Before the chimney a device called the Electrostatic Precipator is present which is electrically charged. The fly ash sticks to the screens of the electrostatic precipitator while the rest of the flue gas escapes through the chimney.
The stuck ash is then scrapped off the screen using a automated scrapper mechanism and collected in a hopper where it's conveyed to a silo either using air or mechanical conveyor system. The fly ash is stored because it can be used in the manufacture of cement or fly ash bricks. Hence its stored in silos and sold to cement plants and not disposed off like bottom ash