The trend in incineration is to ask for the “best technology”, or “ask for the same specifications another country or state uses”. This thinking loses focus on meeting needs and balancing costs. Here are some examples.
We want a minimum Primary burn chamber temperature: It is not possible to establish and maintain high temperature in any incinerator’s primary chamber unless it has no waste in it. If waste is present when the burners ignite the waste absorbs the energy and temperature in the primary will start at ambient and climb slowly. Temperature will peak mid-burn, level off, then subside slowly back to ambient. If you still want to assure a minimum temperature in the primary chamber for your application then be prepared to pay for larger expensive burners and their excessive wasteful fuel. The stack contents are not improved with minimum primary temperature. When waste is loaded after the primary is at minimum temperature (often termed preheating, this can be dangerous to the operator due to waste flashing up when it meets the heat) the temperature will drop considerably below the minimum then slowly climb and retreat as described prior. A “minimum temperature” policy has been discontinued here in the US, in the state of New York who has worked with us to learn about incineration. One of the state officials visited a working Firelake incinerator and was looking at the incinerator from 75 feet away, he asked “When are you going to start the incinerator”? It had been operating the whole time with no odor, no smoke, and no minimum primary temperature requirement. New York has Firelake as the approved supplier to state businesses.
We want a minimum Retention time: How much is really needed to destroy the waste? Consider that a 1/3 second retention has done a good job in many waste applications. To desire a 2 second retention model will raise the size of equipment, purchase cost, and fuel consumption multiples of times more than a 1/3 second model. Why pay for this if it is not needed. If you have a large retention time requirement remember you will have larger chambers, and to maintain temperature more fuel will be burned. How does retention time get measured? Not always equally. Compare calculation methods when retention times and secondary burn chamber sizes are discussed. Is the waste’s energy being included? How is the burner fuel usage included, when it is at a maximum fuel burned or when it is at low burn? How is the chamber volume determined? Is the flue gas “retained” for the whole retention time or bypassing straight through to the stack?
We want a minimum Secondary Burn Chamber temperature: Operating at 1800F, 2000F, 1000C, 1200C is often requested. Again, more temperature, more fuel consumed, lower the retention time. What do you really need to get the job done? Experience shows that smoke is destroyed and no visible exit materials at 1200F (650C). Most health agencies will agree to destroy contamination a moderate temperature is adequate. The high temperature also will shorten the life of the incinerator and its parts. Chose an incinerator that operates at a level to do the job, anything more is often wasted fuel, higher costs, and more service to maintain.
We want x pounds/hour or x kg/hour burn rate: Why? are you limited on time, is there a law, or do you have an extra large amount of waste to destroy? Most applications find they are not needing high burn rates. This allows buying lesser cost machines that are less cost to operate (Firelake designs). Load and walk off, the Firelake will manage the burn and when you return it will be off, and ready for deashing. Remember the retention time discussion, high burn rates produce flue gas faster from the higher burner inputs and waste destruction, leading to bigger costlier machines and higher fuel bills.
We want a scrubber: Is one needed to do a good burn? If no smoke, no odor, low CO is acceptable then no it is not. Did you know the Firelake models in New York operate without scrubbers and particulate is 7 times below the allowable limit? Do you know that a basic reliable scrubber can cost half a million dollars to buy and install, and more money if the expectations are broad. Budget scrubbers are available at less cost with basic water spray chambers the flue gas passes through. What do you do with the affected water after use, if recirculated it will become aggressive and dissolve away piping and pump components. Will you buy chemicals and treat the water to prevent damage? Is the spray cleaning the flue gas as well as expected? What energy is required to operate the scrubber, often is much greater than the incinerator. Bottom line is a reputable scrubber can easily be multiples more expensive and complex than the incinerator. Anything less should be cautiously approached. We hear of many unhappy customers who bought budget equipment.
Word of caution……..simply listing required design specifications does not guarantee the waste will be burned effectively, nor the equipment practical for use. The performance comes from selection of the incinerator design after reviewing the waste application.
Confused yet? Let us help define your project. We can help you select our lowest cost Firelake model to meet that performance.