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Here is a summary of steps as a part of energy management needed to improve the boiler efficiency in industries: 1. Combustion and Waste Heat Recovery System 2. Makeup Water Management System 3. Feed water, Condensate and Blow down Management System 4. Steam and Condensate System Management 5. Steam Generation Management.
Steps to Improve Boiler Efficiency in Industries
- Combustion and Waste Heat Recovery System
- Makeup Water Management System
- Feed water, Condensate and Blow down Management System
- Steam and Condensate System Management
- Steam Generation Management
Step # 1. Combustion and Waste Heat Recovery System:
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(1) Monitor and compare the boiler performance related data to standard targets regularly.
(2) Monitor the flue gas combustibles and the combustion excess air regularly. Adjust as conditions change. Operating your boiler with an optimum amount of excess air will minimize heat loss up the stack and improve combustion efficiency.
(3) The optimum amount of excess air required for the combustion reaction depends on fuel composition and the type of boiler used. Heavier fuels require higher excess air and the stoker fired boilers need more air than oil fired boilers.
(4) Check for and eliminate the entrance of unwanted air into the boiler and flue gas exhaust system.
(5) Keep burners adjusted to optimum efficiency. Establish a burner maintenance schedule. Inspect and replace fault burners.
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(6) Replace obsolete boilers with high-efficiency, low-emissions units fitted with new burner technology and heat recovery options suited to the required demand. Excess air needs of oil fired boilers depend on the design of the burners and atomizers, and on the cleanliness of the burner nozzles. Low excess air burners, which can operate efficiently at much lower levels of excess air, are available for liquid and gaseous fuels.
(7) Consider using fuel direct injection (FDI) technology. A FDI regenerative burner reduces NOx emissions by about 90 percent compared with ordinary regenerative burners.
(8) Convert fuel from oil to natural gas, where gas supplies are available. (Although this may save more money than energy, it has some operational and environmental advantages.)
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(9) Check all the control settings regularly. Fit controls with locks to prevent tampering and unauthorized adjustment.
(10) Maintain the best operating condition of air and fuel controls.
(11) Inspect the fireside and waterside heat transfer surfaces when the boiler plant is shut down; keep the surfaces clean. Ensure that fireside anti-fouling equipment works properly.
(12) Use continuous oxygen monitors and operator adjustments to minimize excess air level. Use continuous oxygen trim to automatically minimize excess air level.
(13) Draw warmer combustion air from ceiling of boiler plant, where the incoming air has the highest possible temperature year-round.
(14) Install an integrated computerized management system for generating and distributing thermal energy.
(15) Consider alternate uses for the remaining heat in the flue gas. Use it for space heating, process or drying the product or biomass fuel.
(16) Install equipment to recuperate heat on the flue gas system. This includes economizers, combustion air pre heaters and flue gas condensers (indirect or direct contact). If already in place, review its efficiency and consider replacing or upgrading it.
(17) Keep unwanted air out:
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(18) O2 monitoring may be drastically distorted by air infiltration into the furnace and the convection passages downstream of the burners. CO concentration is unaffected by air infiltration, and thus gives a more certain indication of combustion.
(19) Avoid subjective judgments; many operators are in a habit of taking judgments based on the appearance of flame or color of flue gas. This usually results in pumping lots of excess air blowing out of the stack.
Step # 2. Makeup Water Management System:
(1) Maintain records of the amount of makeup water used. This helps in analysing the presence of leaks or losses in the system. They also assist in developing a more effective chemical treatment program.
(2) Excessive water use indicates a change in system operation and, therefore, a change in efficiency.
(3) Maximize efficiency and capacity of existing pre-treatment system.
(4) Use of alternative raw water sources of better chemical and heat content quality.
(5) Consider improved pre-treatment systems to minimize boiler blow down losses.
(6) Use of process heat exchangers to preheat makeup water.
(7) Adapt a chemical treatment system in addition to the fixed water treatment.
Step # 3. Feed Water, Condensate and Blow Down Management System:
(1) Return a greater percentage of condensate to boiler
(2) Use condensate monitors to check the contaminants and quality of return water
(3) Use of economizers to preheat boiler feed water
(4) Maintain good steam quality with a program of regular water chemical treatment and the blow down regime.
(5) Evaluate de-aerating system to ensure maximum operating efficiency.
(6) Consider use of boiler blow down heat recovery to preheat makeup water.
(7) Use flash tanks to generate low-pressure steam from the blow down (and use it in other heating applications, such as the de-aerator).
Step # 4. Steam and Condensate System Management:
(1) Rationalize and streamline the steam and condensate network.
(2) Return more condensate to boiler system. Consider installing a system for closed-loop pressurized condensate return.
(3) Identify steam/condensate leakages and correct the problem.
(4) Repair insulation on steam and condensate lines. Add insulation where it is inadequate. Evaluate the economics of upgrading or adding more insulation on current energy cost trends.
(5) Review whether the steam and steam condensate recovery network (and heating coils and other steam-using equipment) has proper drainage. It will eliminate water hammer, losses and damage.
(6) Shut down the steam and condensate branch system when it is not needed. Plug all obsolete, unused and redundant piping.
(7) Set up a steam trap inspection and maintenance program and procedures. Repair and/or replace faulty steam traps.
Step # 5. Steam Generation Management:
(1) Add measuring, metering and monitoring equipment to the boiler and heat distribution systems for fuel, steam, heating fluid, condensate and blow down flows.
(2) Try to stabilize heating demand. To do this, review the schedule for process demand. This will minimize boiler load swings and maximize boiler efficiencies. Try to operate boilers at full load.
(3) Operate steam generator at proper cycles of concentration to control blow down losses
(4) Minimize blow down losses by operating at maximum cycles of concentration with automatic blow down control.
(5) Repair faulty insulation on boilers.
(6) Balance load factor on alternate boilers with respect to overall boiler efficiency ratings.
(7) Replace worn out burners.
(8) Replace outdated, inefficient boiler with new systems.
(9) Repair lost steam generating tubes, baffles and refractory to improve overall efficiency.
(10) Operate the boiler (heater) at the lowest steam pressure (or heating fluid temperature) that meets the needs of the production process.
(11) Convert from indirect to direct steam heating, where appropriate. Convert from steam to heating fluid heating, where appropriate.