Power Conservation and Boilers

Thermal insulation. As much as possible, everywhere possible.

Maximise condensate return and re-use.

Optimise blowdown.

Optimise make-up water treatment.

To the degree possible keep everything around and in the boiler as clean as possible. Perform maintenance when required, clean heat exchange surfaces annually, and keep them clean. Keep fuel as clean as possible, keep air clean, and keep the flame clean and within limits.

Maximize to the extent possible re-use of condensate. If feasible pre-heat water with solar energy.

Be very careful with water treatment, and look for more effective water treatment strategies.

Constantly ask questions, like you are doing now.

what pressure are you running at, is this for process or heating. The lower pressure you can run at the better. Many heating boilers are set to run at 12 psig but would preform fine at 12 ounces per square inch and save a ton of power consumption. A new control would have to be added. If you do not require the high temp then mostly the latent is used and the temp of the steam really does not matter.

The only problem of using lower pressure is that transmission losses start to be come very significant. More steam turns to condensate over distance from the boiler, and more condensate has to be returned, and there is even less pressure available at the equipment.

Yes but at 12 psi you need much bigger diameter Pipes and fittings.

Example. 7 TPH at 10 bar/ 145 psig (practically all Process boilers are designed for this pressure) calls in for a 150mm/ 6" dia steam main.

7 TPH at 12 psig calls in for a 300mm/ 12" dia main.

This then increases the cost of all bends/ fittings & valves + insulation/jacketing materials, sizes of steam traps & PRVs 1/2" or 1" to 1.5" or 2" and on and on with other equipments associated (Control Valves/Flow Meters etc).

The Project Cost goes over by 300% with hardly a saving of 8-10% in steam efficiency due gain in higher latent heat content.

Now not disregarding your option of utilizing steam at 12 psi, which definately has its advantage of the 8-10% saving, it is economical and recommended to generate steam at the Boiler at 10 bar - 14 bar resulting in smaller dia mains & fittings./equipments AND reducing pressure with engineered Steam pressure reducing valves at usage points taking care that all outlet mains after the PRVs are selected at the required low pressure(since at low pressure the steam volume increases and hence requires bigger dia main).

For insulation, paint everything with high-temperature Nansulate paint: http://www.nansulate.com/. Make sure to use the high-temperature version of the paint.

I haven't used it yet, but a colleague of mine has, and he said that it reduced heat loss by 30% in a building whose inside walls he painted.

Other things to do: heat recovery. If you don't have an air preheater in your boiler exhaust (it's a heat-exchanger that transfers heat from boiler-exhaust gases to the combustion air), have one installed. Same thing for an economizer (heat exchanger that transfers heat from exhaust gases to the boiler's feedwater. Also, recover heat from blowdown water by passing it through a heat exchanger that transfers its heat to the boiler's feedwater.

Hhhhmmm ... what else? Regularly check for steam leaks in throughout your plant. This means, checking every steam trap say every three months to see if it's full of water (i.e., it's defective and stays closed, which lets water through to whatever's downstream) or blowing steam to atmosphere (i.e., it's defectives and stays open all the time). If you don't check these, steam losses can become VERY expensive. (Dupont Chemicals in North America estimates that around 8-10% of steam gets lost if steam traps aren't checked and fixed for over a year).

Same thing from pressure-relief valves everywhere in your steam system. When steam is being generated, check to see if they're a little open and either sending steam to atmosphere or dripping with condensation.

Good luck!

DZ

In addition to whatever my respected friend PWSlack said:

1. Briquette your Paddy husk - more calorific value. You get 4 kg steam/1 kg husk loose form. Briquetted will give you 5 kg steam/ 1 kg husk + lesser moisture content + greater storage in dry areas.

2 . Use a pressurized Feed Tank cum Deaerator to increase feed water temperature + 103C to remove all oxygen. No oxygen - no / minimum corrosion of tubes and no / minimum oxygen scavengeing chemicals .(optimize as said)

3 . Use Automatic Boiler Blowdown System. (optimize as said) This saves 3% fuel.

4 . Use Modulating Boiler Level Controllers instead on / off. This will also reduce the size of the Pump HP motor and safeguard against carry over/ priming.

5 . Ensure recommended Boiler feed water chemistry of dicated hardness.

6 . Install a Steam flow Meter on outlet main - This will monitor your Boiler operation telling you when it is operating efficiently and when not. When not can be many reasons : wetter paddy husk, increased TDs level etc.

7 . Carry out Steam Trap Leakage Audit and checking. Ensure NO Traps are leaking.

8 . Install a Boiler Economizer if not available. This saves 3% - 4% Fuel.

9 . Plug all steam leakages from flanges/ valve glands.

10. Apart from insulating the Boiler(as said) insulate all steam mains and condensate return mains inclusive Flanges and ALL valves.

11. Install a Condensate Power Pump to return 100c Condensate to Boiler Feed tank without electricity.

12. Install Inverters on your BIG Blowers.

13. Gets your blowers Dynamic-balanced.

zzzzzzz....zzzz...falling asleep zzzzz