People can't be bothered to make easy energy savings

According to Philips Lighting a standard incandescent light bulb costs around €1, and uses €15-worth of electricity a year. A low-energy one costs €5-6 and uses €3-worth. The payback on investing in a compact fluorescent bulb, therefore, is less than a year. Yet low-energy lighting makes up only 30% of Philips's sales.



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World Environment Day - Some Pledges

My Company’s Message on World Environment Day

1. I will boil only the water I need, rather than filling the kettle every time.

If you boil a full kettle three times a day you’ll raise carbon dioxide emissions by 52kg a year. It takes two trees to absorb that amount. If you only boil the water you need each time, you’ll save energy and reduce your carbon dioxide emissions by more than 7kg a year.

· Carbon dioxide is a greenhouse gas, which contributes to climate change. We need to reduce the amount of carbon dioxide we release to limit the effects of climate change.

· Although trees can be planted to absorb some of this carbon dioxide, we really need to use up less energy in the first place.

2. I will replace two light bulbs in my house with energy saving versions.

Over one year, it would take 13 trees to absorb the 40kg of carbon dioxide you would have emitted into the air.

· The release of carbon dioxide into the atmosphere, caused by the burning of fossil fuels, contributes to climate change. We are experiencing more floods and droughts, and wildlife and plants are also affected.

· Countries that have ratified the Kyoto Protocol must reduce their carbon dioxide emissions.

· Reducing the amount of electricity we use will mean that less fuel is burned for the generators that supply it. Doing this will also save you money.

3. I will turn my biodegradable waste into compost for my garden

Each person dumps 194kg of organic waste a year. That is the equivalent of 12,900 apple cores.

· Much of the waste we produce is collected by local authorities and burned or buried in landfill sites. Burning creates carbon dioxide emissions, which contribute to climate change. Landfill is also unsustainable, as we cannot keep creating more landfill sites.

· The only solution is to reduce the amount of waste we produce, or do something else with it. When you shop, try to find items with less packaging, and when you produce waste such as leftover food, put it in a compost bin and watch your garden bloom.


4. I will volunteer for a green project in my local community.

Many projects are completely reliant on volunteers giving up their time. The sort of projects you could do can range from litter picking, to planting trees, to running a green event.

· Trees planted absorb this carbon dioxide release caused by the burning of fossil fuels etc.

· You’ll also get the opportunity to meet lots of new people, develop new skills and put something back into the community.

5. I will reuse plastic bags for my shopping.

If you throw away four fewer plastic bags every week, you’ll save 4,160 bags from ending up in landfill sites over 20 years.

· Landfill space is limited and will eventually run out if we continue to increase the amount of rubbish we produce. Although there are alternative ways of disposing of rubbish, the best option is to produce less in the first place.

· Plastic bags also spoil the look of our environment. If we re-use the bags we already have, this will mean that fewer new ones are made... and then abandoned.

· Many supermarkets will sell you a “bag for life” which you can reuse, or you could just reuse standard plastic bags by taking a few with you when you go shopping.

6. I will share my car journeys to work with a colleague, or replace those car journeys with public transport.

The average car commuter drives 19 miles a day. Cutting that by half through car sharing would save 648kg of carbon dioxide over one year, the same as that absorbed by 216 trees.

· Carbon dioxide is one of the gases that contribute to climate change when it is released. Planting more trees is an impractical option, and we really need to reduce the amount of energy we use to cut down carbon dioxide emissions.

· Walking or cycling, even just once or twice a week, can help reduce emissions and it has financial benefits. Walking to the bus stop can also contribute to the 10,000 steps a day we all need to do to improve our health.

7. I will switch off my television or computer screen, rather than leave it on stand-by.

Over a year this will save 30kg of carbon dioxide from being emitted into the air - the same as that absorbed by 10 trees.

· The release of carbon dioxide into the atmosphere, caused by the burning of fossil fuels, contributes to climate change. We are experiencing more floods and droughts, and wildlife and plants are also affected.

· Although trees can be planted to absorb some of this carbon dioxide, we need to use up less energy in the first place. Reducing the amount of electricity we use will mean that less fuel is burned for the generators that supply it.

· Countries that have ratified the Kyoto Protocol must reduce their carbon dioxide emissions. Doing this will also save you money.

8. I will take showers instead of baths.

A daily bath uses 16, 425 liters more water a year than a shower.

· Even though the INDIA gets a lot of rain each year, but this is not in every state of INDIA, the density of our population means that water supplies are limited and must be looked after carefully.

· Many underground water sources rely solely on winter rainfall to fill them up. As summers become longer and hotter, this reduces the time that water sources can be refilled.

· We all need to make an effort to save water, or we could face drought in many parts of the country.

9. I will use an outdoor clothesline instead of a clothes dryer

The electricity used to run clothes dryer results in emission of carbon dioxide. Burning fossil fuels, such as coal is not a sustainable way of providing energy, as fossil fuels will eventually run out.

· Although trees can be planted to absorb some of this carbon dioxide, we need to use up less energy in the first place. Reducing the amount of electricity we use will mean that less fuel is burned for the generators that supply it. Doing this will also save you money.

10. I will turn the tap off when I brush my teeth.

If you brush your teeth for three minutes, twice a day with the tap running while you clean your teeth, you are wasting 10,950 liters of water a year.

· Many underground water sources rely solely on winter rainfall to fill them up. As summers become longer and hotter, this reduces the time that water sources can be refilled.

· We all need to make an effort to save water, or we could face drought in many parts of the country.

11. I will switch my household to energy generated from renewable sources.

The electricity used by the average household results in 1,892 kg of carbon dioxide. You can reduce that to zero by switching your electricity supply to a green tariff. That is the equivalent of planting 631 trees.

· Burning fossil fuels, such as coal is not a sustainable way of providing energy, as fossil fuels will eventually run out.

· Coal burning releases carbon dioxide into the atmosphere and contributes to climate change. There are a variety of alternatives we can use such as wave, wind or solar. All of these have various advantages and disadvantages but one thing is clear. We do need to move away. Doing this will also save you money.

12. I will recharge ground water by the method of rainwater harvesting in my house.

Even though the INDIA gets a lot of rain each year, but this is not in every state of INDIA, the density of our population means that water supplies are limited and must be looked after carefully.

· We all need to make an effort to conserve water, or we could face drought in many parts of the country.

· Many underground water sources rely solely on rainfall to fill them up. As summers become longer and hotter, this reduces the time that water sources can be refilled.

If Anyone of us take any one resolutions out of above 12, I will feel happier to contribute something to our society.

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Tray Towers - Few Thumb Rules

Tray Towers

• For ideal mixtures, relative volatility can be taken as the ratio of pure component vapor pressures.
• Tower operating pressure is most often determined by the cooling medium in condenser or the maximum allowable re-boiler temperature to avoid degradation of the process fluid.
• For sequencing columns:
• Perform the easiest separation first (least trays and lowest reflux)
• If relative volatility, nor feed composition vary widely, take products off one at a time as the overhead.
• If the relative volatility of components do vary significantly, remove products in order of decreasing volatility.
• If the concentrations of the feed vary significantly but the relative volatility does not, remove products in order of decreasing concentration.

• The most economic reflux ratio usually is between 1.2 Rmin and 1.5 Rmin.
• The most economic number of trays is usually about twice the minimum number of trays.
• Typically, 10% more trays than are calculated are specified for a tower.
• Tray spacing should be from 18 to 24 inches, with accessibility in mind.
• Peak tray efficiencies usually occur at linear vapor velocities of 2 ft/s (0.6 m/s) at moderate pressures, or 6 ft/s (1.8 m/s) under vacuum conditions.
• A typical pressure drop per tray is 0.1 psi (0.007 bar)
• Tray efficiencies for aqueous solutions are usually in the range of 60-90% while gas absorption and stripping typically have efficiencies closer to 10-20%.
• The three most common types of trays are valve, sieve, and bubble cap. Bubble cap trays are typically used when the low-turn down is expected or a lower pressure drop than the valve or sieve trays can be provided.
• The most common weir heights are 2 and 3 inch and the weir length is typically 75% of the tray diameter.
• Reflux pumps should be at least 10% overdesigned.
• The optimum Kremser absorption factor is usually in the range of 1.25 to 2.00
• Reflux drums are almost always horizontally mounted and designed for a 5-min holdup at half of the drum capacity.
• For towers that are at least 3 ft (0.9 m) in diameter, 4 ft (1.2 m) should be added to the top for vapor release and 6 ft (1.8 m) should be added to the bottom to account for the liquid level and reboiler return.
• Limit tower heights to 175-ft (53 m) due to wind load and foundation considerations.
• The length / diameter ratio of a tower should be no more than 30 and preferably below 20.
• A rough estimate of reboiler duty as a function of tower diameter is given by:
  

Q = 0.5 D2 for pressure distillation.
Q = 0.3 D2 for atmospheric distillation.
Q = 0.15 D2 for vacuum distillation.
Where Q is in Million Btu/hr and D is lower diameter in feet

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Packed Towers - Few Thumb Rules

Packed Towers

1. Packed towers almost always have lower pressure drop than comparable tray towers.
2. Packing is often retrofitted into existing tray towers, to increase capacity or separation. Thus same size of packed towers can handle more than tray towers.
3. For gas flow rates of 500 ft3/min (14 m3/min) use 1 in (2.5 cm) packing, for gas flows of 2000 ft3/min (57 m3/min) or more, use 2 in (5 cm) packing.
4. Ratio of tower diameter to packing diameter should usually be less than 15.
5. Due to the possibility of deformation, plastic packing should be limited to an unsupported depth of 10-15 ft (3-4 m) while metallic packing can withstand 20-25 ft (6-7.5 m).
6. Liquid distributor should be placed every 5-10 tower diameters along the length for pall rings and every 20 ft (6.5 m) for other types of random packing.
7. Packed columns should operate near 70% flooding.
8. Height Equivalent to theoretical stages (HETS) for vapor liquid contacting is 1.3-1.8 ft for 1in pall rings and 2.5-3 ft for 2.0 in pall rings
9. Design pressure drop should be as follows
   
   System Pressure drop (in water/ft)

• Absorbers & regenerators
  Non foaming systems 0.25 – 0.40
  Moderate foaming systems 0.15 - 0.25
  
  
• Fume scrubbers
  Water absorbent 0.40 - 0.60
  Chemical absorbent 0.25 - 0.40
  
• Atmospheric or pressure distillation 0.40 – 0.80
• Vacuum distillation 0.15 – 0.40
• Maximum for any system 1.0
  

I Invite all engineers to add more shortcuts like this, which are useful for chemical engineers.

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