MACROburn Medical Waste Incinerators

The Refractory and Insulation

The vermiculite based insulation around the side and the back walls is 115 to 200mm thick.  This ensures low surface temperatures, higher internal temperatures and lower fuel usage.

The Front face of the incinerator is insulated with calcium silicate that has a very low conductivity to ensure low surface temperatures.

macroburn-medical-waste-incinerator
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The Feed System

The Hydraulic Feed Ram is designed to handle medical waste with a very broad range of calorific values, shapes and densities. Compact design and limited cross section provide better control over the rate of feed and restrict excessive air ingress around the feed opening. Bulky components, too large to pass through the feed ram can be loaded through a manual loading door.  Small to medium animal carcasses sharps containers and buckets can be loaded through the feed ram.

Automatic regulation of the feed rate provides long term control of the rate of combustion.  However, modern medical waste is highly volatile.  It burns very rapidly.  In the short term, a single load of waste can burn so fast as to exceed the design capacity of the incinerator.  The combustion rate is controlled by limiting the primary air and the amount of heat on the waste during the initial stages of volatilisation.  To facilitate this control the ram operates as follows:

  1. Up to five boxes or bags of hospital waste or loose waste are loaded onto an inclined stainless steel chute or raised concrete platform.  (A roller conveyor can be used in place of the chute if the waste is loaded in rigid boxes. The front box is marked position 1 in the illustration.
  2. The front box drops over into the inlet chute on top of the ram in position 2.  The ram is at rest in the position shown in the illustration.
  3. When the incinerator is ready for loading (determined on a combined time and temperature function), the ram moves right back.  The box in position 2 drops into the feeder ahead of the ram.  The next box on the inclined chute then tips into the feeder inlet chute to lie on top the first box.
  4. The ram moves forward, pushing the first box to position 3.  Until this time, the gate is kept closed, preventing any blowback and the ingress of air.
  5. The ram stops with the box in position 3 while the gate opens
  6. The ram then pushes the box to position 4 before returning and allowing the gate to close.
  7. The box in position 4 is shielded from direct heat by a refractory tunnel.  Air from the primary chamber is also restricted.  The initial rate of combustion is controlled and steady.  Volatiles leaving the tunnel are forced to pass through the bed of burning waste.  Halogens and fly ash are trapped in the ash.
  8. As the following box is pushed in, the first box is pushed out onto the hearth, and exposed to the full heat and air supply.

Liquids on the Hearth, in the Feeder and the Fat Pan

The hearth is inclined upwards away from the inlet.  Because refractory and firebrick cannot be made impervious to liquids, the under side of the inclined refractory hearth is lined with stainless steel.  Fat and liquids, penetrating the refractory, run down the stainless steel sheet into a stainless steel pan, located beneath the refractory at the tunnel outlet.  On either side of the tunnel, the pan is exposed to the heat and gases of the chamber.  Molten fats and liquids are burnt away in the pan.

The feed ram is slightly inclined towards the incinerator. Liquids spilt during the feed process run down into the tunnel.  An inclined stainless steel sheet under the floor of the tunnel ensures that all liquids are conveyed to the fat pan for combustion.

Combustion on the Hearth

A semi-pyramidal shape on the hearth promotes distribution of the waste across the width of the hearth.  It also breaks up the solid tube of waste, which would otherwise be formed.

A sharp step at the end of the hearth further assists in breaking and opening up the advancing waste bed.  Gentle opening of the bed promotes combustion without entraining excessive fly ash.

A set of cast iron tuyeres, built into the hearth, admits forced draught under fire air underneath the fire bed.  The tuyeres are so arranged that the air passages blast downwards preventing molten plastics and other liquids from running into the air holes.

The burnt out ash either falls off the end of hearth onto the riddle flap, which opens periodically to drop the ash into the trolley below.

The trolley is emptied once or twice per shift.  The riddle flap is switched off during emptying of the ash trolleys to prevent an inrush of air and entrainment of fly ash.

The Auxiliary Burners

The primary burner is located relatively high in the sidewall of the primary chamber.  The flame is angled downwards, but not so far as to fire directly onto the waste.  When the rate of combustion of the medical waste is low, a vortex motion of the gases in the chamber carries heat down the opposite wall and under the far side of the fire bed.  This promotes rapid primary combustion.

When the rate of combustion is high, volatiles from the waste deflect the burner flame up, away from the fire bed and into the flame port at the entrance to the secondary chamber.  Thus whenever the rate of combustion is too high, heat onto the fire bed is reduced and the primary burner provides secondary heat.  This action is self-regulating and contributes to automatic control of the combustion rate.

The secondary burner provides heat for combustion of the volatiles after they have left the fire bed.  It is located on the sidewall of the primary chamber, directly opposite the flame port.  It is not angled downwards.  It fires straight across the top, rear of the primary chamber and into the secondary, mixing chamber.  This upstream location of the burner provides a longer secondary zone and hence longer secondary retention time.  The heat is introduced before the gases pass through the flame port where high velocities and maximum turbulence occur.  This vastly improves mixing of the secondary heat with the combustion gases.

The Air Supplies

Secondary air is introduced at the flame port to further improve turbulence and mixing.  High gas velocities in the flame port induce secondary air by venturi action.  The higher the gas velocities, the more air is induced.

A small percentage of the primary air is introduced through the tuyeres described above.  It is temperature controlled.

The balance of the primary air is induced by the draught (negative pressure) in the primary chamber.  Most of this air is admitted through the burner quarl and follows a path similar to the primary flame.  It is also automatically deflected into the secondary chamber when the combustion rate is high.

Instantaneous, short term, control of the combustion rate is thus achieved by automatic regulation and deflection of the heat and air supplies.  The principal is also known as “Controlled air”, “Starved air” or “Pyrolisis”.  The feed inlet tunnel also limits the amount of air and heat reaching fresh hospital waste.  All of the above effects are instantaneous.  No moving parts are involved.  The system is rugged and absolutely reliable.  Wear and tear is non-existent.

Saubatech incinerators can recover gold

With over 40 years of experience in incineration technology, Saubatech can now offer a solution not only to the mining industry’s waste problem but also assist in Gold recovery from carbon.

Through various major modifications to the standard incinerator and the use of highly sophisticated filtration units, gold can be recovered in the ash. This is a huge benefit to large gold mining houses, which waste gold in their “refuse”, says Andreas Thieme, director at Saubatech.

“We have found a huge increase in the demand of incinerators to mines as the gold price increases dramatically.

Most of these specialised incinerators have been shipped into Africa, but there is one unit in the USA. The incinerator

can also be used to take care of general mine waste, which often includes hazardous refuse.

Saubatech, a specialist in incineration technology, can burn almost any waste, no matter its consistency – solid, liquid or gaseous.

“With the help of filtration units, dosing equipment and online monitoring, customers can control their waste burning to meet almost any emission standard worldwide,” says Thieme.

The system automatically regulates and deflects the heat and air supplies to control the combustion rate of the

materials inside the incinerator, he says. The incinerators are locally designed and manufactured. Saubatech makes smaller, mobile incinerators for clinics that do not use fuel but are powered by electricity. These are commonly sold to rural clinics, and the company has sold some smaller incinerators to Netcare for use in pilot projects in rural clinics.

A project the company worked on for the United Nations included the development and manufacture of incinerators

that can be used in areas where fuel is scarce. The system is designed for use in Haiti, where people can stoke the

fire in the incinerator with any available fuel, such as wood, dry grass and leaves. The company increased the size of the chimney on the model to increase the airflow, meaning that the incinerator can burn less flammable fuels.

Explaining The Process Of Incineration

Some of the most difficult products that need disposing are often put through a much harsher process known as incineration. The incinerators are normally found in large factories that deal with waste products or disposal of waste products. They are mostly used to dispose of bovine carcasses, poultry, chemical products or anything else where burial is not enough. How does this process work and what exactly is incineration?

In simple terms incineration is the process of that treats waste though combustion of organic materials. This is an extremely high temperature treatment and is quite often referred to as the thermal treatment. The waste products are turned into ash, particulates, flue gases and heat that can also be used to generate electric power. Any harmful pollutants left behind from the flue gases are dispersed into the atmosphere.

Explaining The Process of Cremation

Losing someone dear is definitely the most unfortunate thing that could happen to someone, however we all have to go through this some time or another. One alternative to a traditional burial is through cremation. This article will give you the nuts and bolts of the cremation process.

By the process of cremation, dead human bodies are reduced to basic chemical compounds in the form of bone fragments and ashes. The cremated remains that you get are actually pulverized dried bone fragments and it gets pulverized in a device known as an electric cremated remains processor. The bone gets converted into very fine sand like texture which can be easily scattered.

What Happens to the Body during Cremation?

“Earth to earth, ashes to ashes, dust to dust…”

Many, many years ago, cremation had been thought to be so unnatural and extreme that cremation societies and other advocacy groups were formed to “lobby” for its greater practice. Health benefits were cited as reasons to cremate as well as ecological ones. What about the thought of leaving more land for the living and taking less for the dead? Even 100 years ago, only 1% of deaths in the United States involved cremation.

Today the cremation is preferred by almost 50% of living Americans. There are at least 2,000 crematories within the United States and Canada and they will approach a number of 1 million cremations. The subject of “what happens to the human body is one that many people don’t want to talk about and yet there are many who wonder…