NZ204428A - Burning wool scouring waste in fluidised bed furnace - Google Patents

Description

204428 Patents Form No. 5 PATENTS ACT 19 53 COMPLETE SPECIFICATION After Provisional No. 204428 dated~ 1st June 1983 "BURNING OF WASTE IN A FLUIDISED BED FURNACE" WE, WOOL RESEARCH ORGANISATION OF NEW ZEALAND INC, of Springs Road, Lincoln, Canterbury, New Zealand, a Society incorporated under the Incorporated Societies Act 1909, and APPLIED COMBUSTION SYSTEMS LIMITED, of 42 High Street, Rangiora, Canterbury, New Zealand, a company organised and existing under New Zealand laws , do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement 204428 The present invention relates to the burning or destruction of wool scouring waste materials and more particularly relates to the burning of waste materials produced during a wool scouring operation utilizing an improved fluidised bed furnace.

Known fluidised bed furnaces are an efficient and relatively easily controlled means of achieving near to total combustion of fuel and waste products. Normally the materials burnt in such a furnace are organic matter and fluidised bed furnaces are now commonly used as waste disposal incinerators in which a combustible waste with or without a fuel additive is burnt. Alternatively fluidised bed furnaces are used as steam or heat raising furnaces using conventional fuels such as coal, wood waste or other fossil fuels.

In the past a number of attempts have been made to dispose of waste materials from wool scours. One of these attempts utilized a fluidised bed furnace for the destruction of liquid wool scouring wastes. A problem encountered was that clinker formation is predominant at all reasonable incineration temperatures in the furnace. This clearly reduces efficiency of the furnace. This problem is created because of the propensity which is shown for glass and clinker formation during such incineration. Experience overseas has also shown that alkaline fluxes derived from suint, which is a major constituent of wool scouring waste, have destructive tendencies toward furnace linings or coated heat exchanger surfaces.

An object of the present invention is therefore to overcome the abovementioned disadvantages and to provide a fluidised bed furnace which efficiently burns wool scouring wastes.

Further objects and advantages of the present invention will become apparent from the following description which is given by way of example.

According to the invention there is provided a method of using a fluidised bed furnace for the destruction or burning of combustible wool scour waste, the furnace including a vessel defining a combustion chamber, means through which air under pressure is blown into the bottom of the combustion chamber, means for introducing combustible wool scouring waste to the chamber, the method including the steps of forming within the chamber an active bed containing mainly granular calcium carbonate by blowing air therethrough so that the active bed with the granular calcium carbonate therewithin is in the lower part of the chamber and forms a fluidised bed, and of feeding wool scour waste to the chamber to thereby burn the wool scour waste fed to the chamber.

Further aspects of the present invention which should be considered in all its novel aspects will become apparent from the following description which is given by way of / example only.

An example of the present invention will now be described with reference to the accompanying drawing which shows a diagrammatic section through a fluidised bed furnace according to the present invention.

The fluidised -bed furnace includes a vessel 1 which may be of circular or rectangular cross-section, defining a combustion chamber 2.

The lower part of the chamber 2 is, in use, formed as an active fluidised bed 3 of granular particles. The fluidised bed 3 is created by air being blown through an inlet distributor 4. The bed material is essentially calcium carbonate granules which NEW ZEALAND 2 7 MAR 1987 PATENT OFFiCE 204428 enables a reasonable bed temperature of about 750 degrees C to be maintained at the same time as forming a minimum of clinker.

The furnace is adapted to burn aqueous wool scouring wastes which are injected from source A into the bed by means of nozzles 5. Air from source B is used to distribute the injected wastes and from source C to cool the injection pipes. The size of the fluidised bed and the number of nozzles depend on the quantity of wastes required to be burnt. Prior to the injection of the aqueous wastes, the bed is preheated to 750-800 degrees C by means of gas or oil burners (not shown). If necessary an additional fuel like coal, oil, gas or wood is added to improve combustion in the furnace.

The waste which is a highly polluting material contains large quantities of combustible organic material, in suspension, and generally in a solution form. The waste from a wool scour in its concentrated form, for example, produced by continuous reuse in a wool scouring process followed by concentration by evaporation, reaches a stage where the calorific value is such that it will burn while evaporating any remaining water. • Contaminants present within the waste include potassium, to the extent of about 27% by weight in the water soluble constituents (suint), and silica. The silica constituent of the dirt is highly variable and forms an adventitious wind-blown contaminant of the greasy fleece.

• It has been found during experiments that any clinker formed during burning of the scour waste in the fluidised bed is slowly formed, presumably by interaction between the silica and the 204428 alkali in the feed, is of a small size and is easily screened out by a removal mechanism (not shown) positioned at the bottom of the combustion chamber and generally beneath the bottom of the fluidised bed. The potassium-rich bed material which results from operation of the furnace is a byproduct of value and, for example, may be used as a fertiliser.

Thus by this invention there is provided a fluidised bed incinerator adapted to burn wool scouring waste.

A particular example of the present invention has been described herein by way of example and it is envisaged that improvements and modifications thereto can take place without departing from the scope of the appended claims. 20442S

Claims (6)

WHAT WE CLAIM IS:-

1. A method of using a fluidised bed furnace for the destruction or burning of combustible wool scour waste, the furnace including a vessel defining a combustion chamber, means through which air under pressure is blown into the bottom of the combustion chamber, means for introducing combustible wool scouring waste to the chamber, the method including the steps of forming within the chamber an active bed containing mainly granular calcium carbonate by blowing air therethrough so that the active bed with the granular ' 'i calcium carbonate theriewithin is in the lower part of the chamber and forms a fluidised bed, and of feeding wool scour waste to the chamber to thereby burn the wool scour waste fed to the chamber.

2. A method as claimed in claim 1 wherein the chamber is circular or rectangular in cross-section.

3. A method as claimed in claim 1 or claim 2 wherein the fluidised bed is formed by an inlet distributor positioned in or near the base of the chamber.

4. A method as claimed in any one of the preceding claims wherein the wool scouring wastes are injected from a supply source through a series of nozzles into the chamber after the fluidised bed is preheated to 750-800 degrees C by gas or oil burners.

5. A method as claimed in any one of the preceding claims wherein an additional fuel like coal, oil, gas or wood is added to improve combustion in the furnace. 20 25 - 6 - NEW ZEALAND 2 7 MAR 1987 PATE^r ~ 2Q442&

6. A method of using a fluidised bed furnace for the destruction or burning of combustible wool scour waste substantially as hereinbefore described with reference to the accompanying drawing. WOOL RESEARCH ORGANISATION OF NEW ZEALAND INC By Their Attorneys BALDWIN, SON & CAREY - 7 - few ZEALAND PATENT Off ICE