SK2422001A3 - Process for disposal of treated organic waste by burning thereof in cement-making rotary furnaces - Google Patents

Abstract

Method of disposal of modified organic wastes, particularly meat-bone meal, waste fats, and other processed wastes of animal origin by combusting in the rotary cement furnace, which is heated during the process of sinter firing by generous fuel or by the mixture of generous fuels, eventually by mixture containing generous and alternative fuels. These wastes are added to the cement rotary furnace either through the main burner to the flame with temperatures 1,900 to 2,000 C, and/ or to the hot part of the rotary furnace with temperatures 1,400 to 1,900 C. In this method the part of the energetic contents of the generous fuel or mixture containing generous and/ or alternative fuels is replaced by meat-bone meal, waste fat and/ or by other processed animal wastes in arbitrary chosen ratio maximally to the height of 90 %, which under high temperatures and oxidation in furnace atmosphere in the excess of the combusting air burn with using of their thermal energy. Non-toxic combustion products are subsequently to perfect thermal destruction partly caught in countercurrent firing on the ground raw mixture and on produced sinter and ash produced from the bone minerals re-reacts quantitatively by burning to the sinter substance with mineralising effect P2O5 for production of the sinter phases to the contents of 2 % of P2O5 in the sinter. Added modified wastes have minimal heat value 11 MJ/kg-1 and contain maximally 50 % of the ash with max. humidity 50 %.

Description

Technical field

The invention relates to a process for the disposal of treated organic waste, in particular meat-and-bone meal, fats and other processed veterinary waste of animal origin by incineration in cement kilns.

BACKGROUND OF THE INVENTION

The disposal of hazardous, biologically contaminated organic substrates, banned for inclusion in the food chain and for human production, is now highly topical. Waste of animal origin is processed in sanitation institutes known as rendering plants for meat-bone meal and animal fats, resp. other products. Large quantities of these wastes in the form of bones and viscera are the products of the meat processing industry, as bones make up about a fifth of the animal's weight. Dead animals infected with various diseases, including the now highly problematic BSE disease, known as mad cow disease, also represent a significant group of hazardous wastes.

BSE - bovine spongiform encephalopathy was caused by the feeding of infected meat-bone meal in compound feed containing pathological protein particles - prions, which was administered to bovine animals as an important source of protein, without prior high-temperature processing. Pathological prions cause serious neurodegenerative diseases in humans, known as a new variant of Creutzfeldt-Jacob disease, and in animals known as BSE (bovine spongiform encephalopathy) - a mad cow disease and TSE (transmissible spongiform encephalopathy) known as scrapie of sheep. animal species including humans. The immune system is unable to recognize infectious prions and the disease is spreading uncontrollably through the organism resulting in brain degeneration and death. In the case of livestock, the whole herd must be destroyed when this disease is detected.

Today there is no effective medicine or preventive vaccination against these diseases, prions are very resistant, survive in the external environment and are difficult to dispose of with common disinfectants. The only possible protection against the spread of these diseases is the destruction of meat-bone meal from hazardous animal waste by incineration.

In conditions of common municipal waste incineration plants, where the temperature reaches 700 - 900 ° C, max. 1200 ° C, there is a danger of imperfect burning of organic

PV212-2CQ1 r c. c - r. · carbon of meat-bone meal, and there is also a problem of the use of waste ash. The energy potential contained in the meal is not utilized in conventional combustion chambers. The disposal of flesh-and-bone meal by improperly selected technology may cause additional environmental problems associated with incomplete combustion, which could result in the formation of toxic flue gases containing CO, carbon black, organic pyrolysis compounds, dioxins, furans, HCN under H ₂ S reducing conditions and the presence of additional addition halogenated organic compounds that are a major environmental burden.

The perfect combustion of organic waste should result in flue gases containing CO ₂ , SO2, NO _X , H2O, hydrogen halides and ashes.

Several patents address the problem of the disposal of hazardous bio-waste by combustion in combustion chambers of different designs. Wastes are e.g. incinerated in grate furnaces according to the published international application WO 9500804, respectively in fluidized bed layers according to U.S. Pat. No. 214859, SK 278 599, DE 4414579, in the form of various pellets according to US 5,001,993, or various lumpy, liquid and resp. gaseous waste according to FR 2 661 734, in combustion plants in various design variants EP 0751347, WO 9626021, US 3782301. However, these patented solutions do not disclose methods for the disposal of ashes resulting from the incineration of infectious animal waste and also do not exploit the energy potential generated by incineration waste.

Combustion of animal bones in a suitably treated apparatus at temperatures of about 650 ° C is dealt with in US Patent 4,000,705 to form ash and volatile hydrocarbons that can be either condensed, released into the atmosphere, or burned.

The use of meat-bone meal as an additional fuel for the fluidized-bed combustion of mechanically dehydrated sewage at temperatures of 850 to 1150 ° C is disclosed in published international patent application WO 995230.

High-temperature high-capacity incineration of hazardous wastes in blast furnaces where the temperature of the bottom of the furnace reaches about 2000 ° C is described in CZ patent 284 954. The wastes are added to the furnace charge and dosed into the furnace from above. blast furnace gas. Partial melting of the charge, development of blast furnace gas, pyrolysis and formation of pyrolysis fumes occur. The blast furnace gas contaminated with the fumes is discharged to a second blast furnace for combustion. A disadvantage of this solution is that the finely grained contaminated material can be excreted from the batch due to e.g. In case of malfunctions, pyrolysis products can escape into the atmosphere, gaseous SO2, HCl, HF are not captured and as blast furnace slag is produced as natural waste of iron production technology.

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Combustion of solid combustible wastes in the form of pellets as a supplementary fuel in a cement rotary kiln is disclosed in US Patent 5,724,899. Pellets are dosed into the furnace by a special device located on the furnace shell and burn almost before entering the salting zone, creating a secondary furnace furnace. rotary kiln. In this way, however, there is a risk of contamination of dust from the cement rotary kiln with non-combusted fine contaminated material resulting from the decomposition of the burning pellets and entrained flue gases with high flow rates, since the pellets are not dosed to the highest temperatures in the melt zone of the furnace. practically impossible due to high temperatures and stickers.

EP 0501944 discloses the use of preheated waste air from refrigeration industrial equipment, such as a cement clinker cooler, for the combustion of bio-waste, but it also does not address the problem of ash formation.

The disadvantage of the prior art in the field of disposal of bio-waste, especially such as meat-bone meal and other processed animal substrates, is generally their inefficient ecological and economical disposal by incineration in conventional combustion chambers, where there is a possibility of toxic fumes by incomplete combustion. utilization of their energy content and the inconvenience associated with the recovery or disposal of ash from the incinerated infectious waste.

The object of the present invention is the safe, hygienic, ecological, waste-free and economical disposal of meat-bone meal and other processed animal waste from rendering plants with a possible microbiological infectious negative effect on living organisms by burning as an alternative fuel in rotary cement kilns.

SUMMARY OF THE INVENTION

This objective is achieved by the disposal of treated organic wastes, in particular meat-bone meal, waste fats and other processed veterinary wastes of animal origin by incineration in a cement-fired rotary kiln heated by the noble fuel clinker firing process, where these wastes are added to the cement rotary kiln a main burner and / or calcination burner directly into the flame, and / or through an auxiliary burner to the flame at temperatures of 1900 to 2000 ° C and / or to the hot part of the rotary kiln at temperatures of 1400 to 1900 ° C, the noble fuel content or the noble fuel mixture, or the mixture containing the noble and alternative fuels, is replaced by flesh-meal, waste fat and / or other processed animal wastes which at high temperatures and oxidizing furnace atmosphere in excess of combustion rrrrr-C The air burns out using their thermal energy, whereby non-toxic flue gases, after perfect thermal destruction, are trapped in part by countercurrent firing on the ground raw material mixture and forming clinker and bone ash. of minerals by burning, quantitatively reacts to the clinker mass with the mineral-affecting effect of P2O5 phosphorus oxide on clinker phase formation.

It is preferred to utilize the mineralizing effect of P2O5 phosphorus from the ashes of meat-and-bone meal to produce clinker at firing up to 2% of P2O5 phosphorus oxide in the clinker, preferably up to 0.5% of P2O5 phosphorus oxide in the resulting clinker.

It is also advantageous if the treated organic waste to be added has a minimum calorific value of 11 MJ / kg, preferably above 20 MJ / kg and contains at most 50% by weight. ash with a maximum humidity of 50%, preferably below 10%.

Advantages also include that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by a meat-bone meal of max. up to 40%, preferably up to 5% or waste grease up to max. 90%, preferably 30%.

It may also be advantageous that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by a mixture of meat-bone meal and waste fat or other organic waste of animal origin in any selected ratio up to max. 90%.

At high temperatures achieved by clinker burning in an oxidizing atmosphere in excess air and a sufficiently long residence time of the flue gases and the fired material in a cement kiln rotary kiln, complete high-temperature destruction of all organic substances occurs without the possibility of toxic flue gases.

The countercurrent flow of material and flue gas and their sufficiently long residence time in the cement rotary kiln - heat exchanger system ensures the binding of gaseous acidic compounds of chlorine, flora and sulfur to the alkaline raw material mixture to form alkaline compounds which then bind into the resulting clinker structure in the firing process.

The firing results in non-toxic flue gases containing carbon dioxide CO ₂ , nitrogen oxides NO _X , water vapor H 2 O, and oxygen O 2, with a reduced content of sulfur dioxide SO 2 and hydrogen halides. High combustion temperatures, sufficiently long exposure, perfect destruction of organic substances, their oxidation in excess of O2 and the overall technological arrangement of the cement rotary kiln do not allow the re-generation of toxic flue gases containing dangerous dioxins, blowers and other organic compounds as observed in conventional incinerators for waste disposal.

An important advantage of the combustion of organic substrates of animal origin, particularly meat-bone meal and bone-containing waste in cement kilns, is the immediate disposal of the ash produced by its quantitative incorporation into the clinker phase structure by chemical reactions and physical processes, becoming an integral part thereof.

One of the essential advantages of burning meat-bone meal and other organic waste, especially processed animal waste of animal origin with min. calorific value 11 MJ / kg, max. 50% and with an ash content of max. 50%, such as e.g. waste animal fats from the risk group of animals is the saving of expensive noble fuels commonly used in cement technology (natural gas, fuel oils, coal). These wastes are used as alternative fuels to a specified extent so that the technological process during the clinker firing and thus the overall quality of the cement produced are not negatively affected. For meat-bone meal, it is a substitute of noble fuel in the range of up to 40%, usually up to 5%, in waste fat the range is wider and with suitable burner adjustments even higher waste fat dosing is possible than 70% than substitute noble fuel into a sufficiently heated oven , since the fat has a comparable calorific value to that of a noble fuel and practically zero ash content.

It may also be advantageous to use a mixture of meat-bone meal and waste animal fat, which is a well-transportable suspension, as an alternative fuel for firing clinker.

The limiting factor of the amount of meat-bone meal used as an alternative fuel in cement clinker firing is the content of P2O5 phosphorus in ash and consequently also in clinker. Amounts of P ₂ O 3 in the clinker are at trace levels of up to 1.5%, typically 0.05 to 0.25%. Concentrations above 0.5% can sometimes cause serious quality problems and reduce cement strengths, especially at an earlier stage. Additions of P2O5 phosphorus pentoxide above 0.5% stabilize dicalcium silicate C ₂ S at the expense of tricalcium silicate C ₃ S, which is the most important in terms of strength, clinker material, or decompose tricalcium silicate C ₃ S into dicalcium silicate C ₂ S and calcium oxide CaO. Concentrations up to 0.5% P2O5 phosphorus pentoxide significantly increase initial strengths (due to increased C ₃ S hydraulics), up to 2% P2O5 phosphorus pentoxide achieves cement strengths, higher concentrations above 2% strength. The amount of P2O5 phosphorus oxide in the clinker up to 2% has a mineralizing effect on the overall clinker-forming process and improves the grinding capacity of the clinker.

The variability of the ash composition does not require extraordinary measures for homogenizing meat-bone meal or other processed organic waste of animal origin.

The composition of the ash does not require chemical changes, resp. only minimal corrections of the chemical composition to the CaO content in the preparation of the raw material mixture.

The perfect incineration of animal waste to non-toxic flue gases and the quantitative incorporation of ash into the clinker structure does not require the continuous monitoring and control of the generated fumes.

Overview of the figures in the drawing

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail with reference to the drawing, in which: FIG. 1 is a diagrammatic illustration of a cement rotary kiln for carrying out the process of disposing of treated organic waste according to the invention based on Example 2.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

In a cement kiln rotary kiln 1 with an output of 1700 t clinker per day, the waste meat-bone meal was burned in an amount of up to 5% of the energy content of the noble fuel (natural gas with a calorific value of 33.5 MJ.m- ³ ). The meat-bone meal was fed through the main burner 4 into the flame, where it was completely thermally destroyed. In clinker, an increase in P2O5 from the original 0.15% to 0.4% P2O5 was observed. During firing an increase in hourly output by about 3% was observed. The cement obtained by grinding the clinker and the solidification regulator thus exhibited no deviation from the standard properties, the cement leaches did not contain increased amounts of heavy metals. The flue gases downstream of the heat exchanger contained no toxic compounds, and ash from the burned organic substrates was not identified by dust.

Example 2

In a cement kiln rotary kiln 1 with a precalciner channel 2 with an output of 1700 t clinker per day, the animal animal fat from the rendering plant was burned up to 30% of the energy content of the noble fuel (heavy fuel oil with a calorific value of 40 MJ.kg ^-1 ). The preheated mixture of animal animal fat and heavy fuel oil was fed through a calcining burner 5 into a flame in the precalciner channel 2 between the heat exchanger 3 and the rotary kiln 1 where it was completely thermally destroyed. No decrease in performance and no technological problems were observed. The cement obtained by grinding the clinker thus prepared and the solidification regulator showed no deviation from the normal

properties, leached cement did not contain increased amounts of heavy metals. The flue gases after the heat exchanger contained no toxic compounds.

Example 3

In a cement kiln rotary kiln 1 with an output of 1700 t of clinker per day, a mixture of meat-bone meal and animal animal waste was burned in a weight ratio of 1.1 in an amount of up to 200 kg per hour. The preheated mixture was fed through an auxiliary burner 6 into the hot portion of the rotary kiln salting zone where it was completely thermally destroyed. In clinker, an increase in P2O5 from the original 0.15% to 0.18% P2O5 was observed. The cement obtained by grinding the clinker and the solidification regulator thus exhibited no deviation from the standard properties, the cement leaches did not contain increased amounts of heavy metals. The flue gases downstream of the heat exchanger contained no toxic compounds and no dust from the burned organic substrates was identified in the dust collectors.

The examples given are illustrative only and do not exhaust all the possible uses of treated organic wastes, in particular of animal origin, as alternative fuels.

Industrial usability

The process according to the invention is primarily concerned with the disposal of meat-bone meal, waste fats and other organic substrates from rendering plants. The method of disposing of treated organic waste by incineration, in particular meat-bone meal and other processed veterinary waste of animal origin in cement kilns rotary kilns achieves reliable and waste-free disposal of these waste.

Claims (6)

PATENT CLAIMS 1. A method of disposing of treated organic waste, in particular meat-bone meal, waste fats and other processed veterinary waste of animal origin by incineration in a cement rotary kiln heated by a clinker burning process with a noble fuel or a mixture of noble fuels, these wastes are added to the cement rotary kiln either through the main burner and / or the calcining burner directly into the flame, and / or through the auxiliary burner into the flame at temperatures of 1900 to 2000 ° C and / or to the hot part of the rotary kiln at 1400 to 1900 ° C, characterized in that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by meat-bone meal, waste fat and / or other processed animal waste which at high temperatures and an oxidizing furnace atmosphere burnt in excess combustion air using their thermal energy, whereby non-toxic flue gases, after perfect thermal destruction, are partially captured by countercurrent firing on the ground raw material mixture and the clinker formed and the ash formed from bone minerals burns quantitatively into the clinker mass. with the mineralizing effect of P2O5 phosphorus oxide on clinker phase formation. Method according to claim 1, characterized in that up to a content of 2% of P2O5 phosphorus oxide in the clinker obtained from the ash of meat-bone meal or pellet. Bone-containing organic waste on firing has this mineralizing effect on clinker formation, preferably maintaining the level of P2O5 phosphorus oxide in the clinker at a level of up to 0.5%. The process according to claim 1, characterized in that the treated treated organic wastes added have a minimum calorific value of 11 MJ / kg, preferably above 20 MJ / kg and contain at most 50% by weight. ash with a maximum humidity of 50%, preferably below 10%. Method according to claims 1 and 3, characterized in that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by a meat-bone meal of max. up to 40%, preferably up to 5%. Method according to claim 1 and 3, characterized in that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by waste grease up to a max. 90%, preferably 30%. Method according to claim 1 and 3, characterized in that part of the energy content of the noble fuel or of the mixture of noble fuels or of the mixture containing noble and alternative fuels is replaced by a mixture of meat-bone meal and waste fat or other organic waste of animal origin in any selected ratio up to max. 90%.