Steps in Boiler Design

STEP-1
Received data from customer
Steam output, feedwater inlet
Fuel analysis, boiler type
Power plant heat balance
STEP-2
Boiler Thermal Sizing:
Combustion, efficiency, steam output calculation,
Furnace, Back pass & Cyclone sizing,
Metal temperature calculation,
Emission calculation, Air Heater Calculation, etc.
Iteration with customer/steam turbine back to STEP-1
STEP-3
Pressure part material selection and ASME calculation & Pipe Stress Analysis:
Tubing, pipe manifold, drum and internal piping & external piping
Furnace Sizing, Boiler Circulation
STEP-4
Non Pressure Part selection and calculation/Simulation
Structural steel Design calculation
Pressure part hanger calculation, etc.
Iteration to STEP-3 for pressure part weight and arrangement
STEP-5
From step-2, perform external piping selection:
Material selection, ASME calculation, Pipe Stress Analysis
Pressure Drop Calculation
STEP-6
Create Pressure Part Arrangement
Iteration with Step-3/4/5
STEP-7
Create General Arrangement & Layout
Iteration with Step-3/4/5/6
STEP-8
Create P&ID Drawing
Steam/Water Diagram, Flue Gas Diagram,
Fuel Diagram, Limestone Diagram, Inert Injection Diagram
STEP-9
Create Bill of Material of Structural & Support (Non Pressure Part)

STEP-10
Create Bill of Material of Tubing, Piping (Pressure Part)
STEP-11
Create Drum Arrangement Drawing,
Drum Internal Drawing, Welding Detail
STEP-12
Create Pressure Part Drawing & Welding Detail:
Evaporator, Furnace wall, superheater section
STEP-13
Create Non Pressure Part Drawing & Welding Detail:
Structural Steel, Casing, Ducting, Cyclone, Stack,
Air Heater

STEP-14
Sizing & Create Coal Silo, Inert, Limestone
Create drawing, specification of silo system
STEP-15
Create Specification & Sizing of Coal Crusher & System
Create emission equipment, baghouse, dust collector (if required)
STEP-16
Create Equipment List & Data Sheet:
Primary Air Fans, Secondary Air Fans, Blower,
Feed Pump, Start-up burner, Damper,
Ash Screw Cooler,
Soot blower, Chemical Injection System, etc.
STEP-17
Create Valve List & Valve Data Sheet:
Manual valve, pneumatic block valve, MOV,
Control Valve, Blowdown valve, desuperheater system, etc.
STEP-18
Create Instrument List & Instrument Data Sheet:
Flow/pressure/temperature transmitter/gauge
Flue gas analyzer & sampling system
Water/steam sampling and analyzer
Create Bill of material of instrument tube & fitting
Create drawing & bill of material cabling system
STEP-19
Boiler Operation and Control Concept
Create functional control diagram
Create logic diagram
Verify/Iterate with P&ID and Selected Equipment
STEP-20
Electrical System
Create bill of material of electrical
Create drawing & bill of material electrical cabling system
STEP-21
Pipe routing for external piping & 3-D Drawing, Pipe Stress Analysis
Feedwater piping system, steam piping system,
fuel/inert/limestone piping system, ducting for flue gas
Iteration with selected equipment
STEP-22
External piping: Pipe Stress Analysis & Pipe Support Drawing
Pipe Insulation System, Ducting & Casing Insulation System
STEP-23
Refractory Lining System
Anchoring System, Material Selection, Testing and Installation Procedures
STEP-24
Iteration to the previous STEP, to verify selected equipment
with design data.

Note:
In general, as one system of the boiler, each of process and step need to be verified and iteration with other process or system.
Drawing output, data sheet, etc. will be submitted to sub-vendor for fabrication, manufacturing or equipment supply.
Selected equipment shall be verified with the design data, the iteration process is required to verify the design data compare to manufacturer data.

Ammonia-Based Flue Gas Desulfurization

Flue gas desulfurization (FGD) systems using lime or limestone as the chemical reagent are widely used throughout the world for SO₂emissions control at coal-fired power plants. Ammonia-based systems, however, are emerging as a viable alternative to address limitations with respect to liquid and solid waste generation and handling. Efficient Ammonia-Based Desulfurization Technology (EADS) does not generate any liquid waste streams or undesirable solid byproducts that require disposal; rather, the closed-loop process produces a salable ammonium sulfate fertilizer byproduct which can reduce more than 50 percent of the operating cost.

Typical Lime/Limestone Forced Oxidationv  Wet Scrubbing Process Schematic Efficient Ammonia Desulfurization Process Schematic If an LSFO process had been applied to this project along with commercial sales of the byproduct gypsum, the annual operating costs would be $14,642,000. In comparison, the EADS process can essentially eliminate these costs while generating a profit of over US$500,000 from the sale of ammonium sulfate (at US$90/ST), netting total annual savings of approximately $15,000,000. Conclusion The EADS technology enables power plant and industrial boiler operators to meet strict environmental regulations while providing economic benefits. EADS is available under several business models, including engineering packages with supply of key equipment and parts, project engineering, procurement and construction, Build-Operate-Transfer and Build-Operate-Own.

The M.V. Recyclone by James Dyson

The M.V. Recyclone by James Dyson

“By skimming a highly concentrated flow of larger sized plastics in polluted rivers, the M.V. Recyclone would effectively mine a major source of the pollution before it reached the sea,” the British engineer explained in an email.

“Large skim nets unfurl from the rollers at its stern and are anchored on each side of the river. Hydraulic winches wind them in and out. The nets face upstream and skim the surface of the river for floating debris. The plastic waste is shredded on board and then different grades of plastic are separated by a huge cyclone–very similar to the way our cyclonic vacuums work,” he said.

"The concept I propose, the M.V. Recyclone, would combat this ever growing problem of plastic waste making its way to our oceans by filtering out debris from the rubbish-stricken rivers that feed into them. By focusing on the polluted rivers, the M.V. Recyclone could tackle a concentrated stream of plastic, catching it before it spreads."

We need to work on this idea with James Dyson, and harness the power of this idea into a usable technology that will help clean our rivers, which in turn will safeguard our seas, which in turn will increase the overall value of our country’s resources.

Source: Planetcustodian , FastCompany

Electricity (units) is used by 1.5 ton split AC?

Around 1.5 units per hour, provided the compressor is on.

But that is a rough estimate, your actual power consumption varies every single second. Let's dive in a little deeper and see how these things relate to each other.

If you carefully look at your air conditioning unit, you'll probably see a label like this :

The power rating printed on such a label is when the AC is under a stable load, the current is constant, the compressor is working, there's no back emf being produced in the induction coils, and above all the supply voltage is exactly equal to 230 volts at 50 Hz.

In this stable state, the AC unit is consuming 1.5 units of electricity per hour.

That said, not always is the compressor running. If your AC has a thermostat and a temperature setting, once the ambient room temperature reaches to the set limit, the compressor shuts off and only the circulating fans work.

In this case the power consumption is almost equal to a ceiling fan, with my test bench, I got readings around 0.3 amps at 230 volts. That is equal to 0.06 units per hour, almost equal to a 80 watt incandescent bulb.

Another test I conducted : Under extreme load, at a room temperature of about 32 degree Celsius, the power consumption rose to almost 1.8 units per hour, or 1800 watts.

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How do you calculate your power consumption :

The commercial unit of electricity is kWh, also called as BTU (Board of trade Unit), which equals to one kilowatt load used for 1 hour.

Units = Power in Watts * time in seconds / 3600000

Or

Units = Power in Watts * time in hours / 1000

Or

Units = Power in kiloWatts * time in hours

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You can guess the power consumption by these steps :

For while the compressor is working :

• Note down the peak power usage from the label of your AC unit.
• Now do the following maths :
  Units Consumed = Power * Hours of usage / 1000
• Calculate your projected consumption part 1

For while the circulating fan is working :

• Take the power usage in this case as a average of 80 W.
• Do the following maths :
  Units consumed = 80 * Hours of usage while the compressor is off / 1000
• Calculate your projected consumption part 2

Try this for the average time you use your air conditioner in a day, and add the two to get the daily units consumption. Multiply this with the cost of 1 unit of electricity (around Rs. 6) and you'll get the bill for a single day. Multiply by 30 to get the monthly expenditure.

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For example :

I use my AC unit for around 14 hours a day, at 24 degree Celsius.

During the 14 hours cycle, my compressor works for about 4 hours, while for the rest 10 hours, only the fan works.

Consumption Part 1 : 1500 * 4 /1000 = 6 units
Consumption Part 2 : 80* 10 /1000 = 0.8 units
Total Consumption : = 6.8 units
Bill for a single day : = 6.8 * 6 = 40.8
Bill for a month : = 40.8 * 30 = Rs. 1224

But the fact is, that never do you get the exact 230 V supply, nor does the operating conditions remain the same, so for the projected output, add a uncertainty factor of 20 % positive, and the value will be quite close to the actual consumption.

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Keep in mind that this varies from AC to AC, and to get a fairly accurate reading is almost impossible.

MOSFETs are preferred over bipolar junction transistors (BJTs)

The reason MOSFETs are preferred over bipolar junction transistors (BJTs) is that the gate (base) current is negligible in MOSFETs compared to BJTs. You "waste" base (gate) current in BJTs to gain control over the collector (drain) current. But, in the case of MOSFETs, you don't have to sacrifice gate (base) current to have that control. 

Complementary MOS (CMOS) takes that concept even further and makes the drain current zero in steady DC state.

Because of these properties, MOS transistors have driven BJTs out of existence from electronic circuits, practically speaking

Reactive power production and the effects of reactive power in the grid

REACTIVE POWER ASSISTS THE FLOW OF ENERGY IN AC CIRCUITS.

Below is the explanation in layman's terms - 

Consider there is a small river dividing two cities and you need to build a bridge over it to connect both the cities. After building the bridge, you also need to construct a house on the other side of the river. 

For the whole work including bridge and house, you've got only 100 wooden planks of which 10 are used to create a bridge over the river. The workers will use this bridge to cross the river and transport items and construct a house on the other side. Here the main work is to build the house on the other side for which we've created a bridge to move from one point to another.  In this case, are the wooden planks used in constructing the bridge directly contributing to the building of a house ? NO. We've used 10 wooden planks for bridge and that cannot be used for building the house. 

And this - THE BRIDGE is what reactive power does. 
100 wooden planks are the total complex power of which some amount is used to create a bridge (10 planks) and remaining active power (90 planks) does the useful work. This is why we say reactive power does not do useful work.

In transmission lines, reactive power maintains the voltage level of the line so that active power can flow to do useful work and this is why we compensate reactive power by external means. It is very much necessary for the line to operate, for active power to flow.

And for how it is done, a capacitor (to supply reactive power to increase voltage profile) or an inductor (to absorb reactive power to decrease voltage profile) is connected in parallel to the transmission line.
Nowadays, power electronic compensators are used for the automatic and varying degree of compensation.

The Ground

This is the most important and basic thing, that every electronic engineer has to understand. The ground.

Many people just think that Ground is something that is Zero Volt. No, it's not. Speaking about voltage, it can also be called Potential Difference. Which means, the difference between two points, when measured, is what is known as Voltage. So it would be more helpful if one of these two points is a known one. And this known reference point is Ground.

The ground need not be Zero volts always. It can be any voltage from which you actually measure the intended thing. It is like you are measuring your height by standing on the ground, which serves as a base reference. However, you can also measure your height by stand on a chair or something. It is always the difference that matters.

So you can even take 200V as your reference and measure the voltage at 205, the potential difference is 5V and the ground here is 200V.

The ground also serves as a return path for the current to reach its source.

Difference between torque angle and load angle in a 3 phase synchronous machine

The load angle primarily used for synchronous generator and torque angle is the same thing for the synchronous motor. Power angle is also same in the context of synchronous machines but it is more generic – also used in power transmission line.

Let me explain what they are:


Load angle (or Torque angle): For a synchronous generator, the magnetic field rotates at synchronous speed and the rotating magnetic field is created in the stator. These two fields are not fully aligned. The stator field lags the rotating field. This lagging expressed in angle is called load angle. The power developed by the generator is directly proportional to sine of this angle. This angle plays an important role in the stability of the generator. If the angle goes beyond 90º, the generator becomes unstable. This may happen when sudden change of large load occurs or fault sustains longer time. The generator instability is one of reason for massive blackout in case of major fault occurs in transmission line.


For the case of a synchronous motor, the angle is called torque angle and the rotating field lags the stator field in this case.


Power angle: For a generator, the power angle is the difference between the generator induced voltage and the generator terminal voltage. The value of the power angle is same as the load angle. So, in the context of the generator, power angle and load angle mean the same thing.
For the case of a transmission line, the power angle is the angle between the angles of the voltages at two different points (bus). The transfer of power between the two points of the power system is proportional to the sine of this angle.
Though there is a distinct difference between these three terms, they are used anonymously in many cases in a power system.

Real, Reactive, and Apparent power

"Real" power is the power that does actual work - e.g: creating heat, lifting loads, etc.

"Reactive power" is power where the current is out of phase with the voltage, and the "Volts x amps" doesn't do any real work. The current that charges a capacitor, for example, or current that creates the magnetic field around a coil for another.

"Apparent power" is the mathematical combination of these two.

The best representation is a vector diagram, where "Real" power is represented by the positive X-axis, and reactive power is represented by the Y-axis. Inductive power - the current involved in creating and maintaining an electromagnetic field around a winding - can be represented by the positive Y-axis. Capacitive power can be represented by the negative Y-axis. Obviously, those two will cancel each other somewhat, leaving a vector that is either positive or negative on the Y-axis.

Take, for example, a large three-phase induction motor. A small but not insignificant amount of current is necessary to magnetize the windings of the motor. Its capacitive component is negligible. This current does not contribute to the production of shaft torque, and can be represented by the current on the positive Y-axis we'll call Q. The portion of the current that does actual work can be represented by the positive X-axis we'll call P. This produces a vector sum with a value of Sqrt(P²+Q²) as shown below:

CosΦ is the power factor, which for a three-phase induction motor is generally on the order of 0.8 to 0.9. In order to reduce Φ and improve power factor, quite often capacitors are added to the motor circuit. The function of these capacitors is to provide the magnetizing current, thus reducing the amplitude of the reactive power Q. Remember, inductive power is positive Y-axis, capacitive power is negative Y-axis. The lower the angle of Φ, the closer the apparent power is the real power. In actuality, once the motor magnetic field is established, the current required to sustain it circulates through the added capacitors and is not drawn from the utility.

The generating utility cares about the apparent power because whether the current being drawn is producing useful work or not, the utility has to be able to provide that many amps. The better the power factor, the lower the total amp draw.

Electrical power transmitted at low frequencies and not at high frequencies

GENERATION

• Power is generated from Synchronous machines (Alternators) which rotate at a particular speed called the synchronous speed is given by

Ns= 120f /P 
and the frequency is given by :
f= P*N /120 

Now to produce the voltage at a high frequency, two things have to be increased : 

1. Number of poles in machine
2. Speed of machine

But these two factors contradict each other. Suppose for example you have a hypothetical machine of 50 poles, you cannot rotate it at higher speeds because of high centrifugal force, vibrational force and mechanical strength.

Since the number of poles in this Alternator have increased (compared to two pole  High-speed turbogenerators rotating at 3000/3600 RPM at 50/60 Hz respectively),  the diameter of the machine will increase which will make the size of machine large. 

Now that to produce power at a High frequency, you would have to rotate the machine at high speeds which would require higher steam input for the same amount of power at a higher frequency.

The Higher input to alternator will deteriorate it mechanically. To paraphrase a high-frequency alternator needs to be mechanically robust and thus will require a larger size and more material in construction.


TRANSMISSION 

• Coming to your actual questions about transmission of power at high frequency, We need to realize the model of transmission line

A transmission line physically is an R, L, C, G circuit with R and L being series parameters. *R being frequency independent to be more specific*
While C and G are shunt parameters of line *G being frequency independent* 

If the voltage at high frequency is used to transmit power

1. Drop across inductor will increase as V = I*X =I*2*3.14*f*L (f being the frequency).
2. A higher drop will cause the line voltage to sag.Hence the coveted flat voltage profile will not be obtained.
3. The voltage will decrease with increase in length and it will be less most at the receiving end (where it is needed the most).
4. Corona loss is directly proportional to frequency, hence the losses due to corona will increase
5. This will cause more interference with communication/telephone lines.
6. High losses in transmission wires due to skin effect.
7. Because of skin effect, the cost of conductor material will increase as the conductor is not utilized fully at high frequencies.
8. The economy of transmission is a major point while designing transmission lines. increasing the cost of the conductor will make the system uneconomical
9. Since the resistance due to skin effect increases ( assume Rac=1.6Rdc), line losses (I^2R ones) will increase and hence the power transmission capability will decrease
10. FACTS devices or compensators will be required for reactive power demand/supply making the system even more costly.

DISTRIBUTION & UTILIZATION
Even in distribution, the high-frequency AC will not be that efficient :

1. We use a lot of power electronic devices. A high frequency will cause large switching losses.
2. Harmonics of higher frequencies being fed back to the grid , filter requirements might be there.
3. Poor voltage regulation
4. Possibility of  thermal noise/shot noise /white noise (high frequency ) interference with home appliances