METHOD FOR PROCESSING MEAT-AND-BONE MEAL

Description

CROSS-REFERENCE

This application claims the benefit of priority under 35 U.S.C. § 119(e) from Portugal Patent Application No. 119277, filed on Feb. 27, 2024 and European Patent Application No. 24162100.2, filed Mar. 7, 2024, which are hereby incorporated by reference as if set forth in their entirety herein.

TECHNICAL FIELD

The present disclosure relates to a method for processing biomass, preferably meat-and-bone meal. Particularly it relates to a method and apparatus which is capable of processing meat-and-bone meal reliably and in large quantities for obtaining energy and ashes which can be used for further applications.

BACKGROUND

Meat-and-bone meal has been conventionally produced by crushing the remains of slaughtered cattle and subjecting them to treatments such as pulverization, steam heating, oil extraction, among others. Since meat-and-bone meal contains nitrogen and phosphorus, it was generally used as an excellent feed and fertilizer. However, the problem of bovine spongiform encephalopathy (as known as “BSE”) has arisen, and the cause of this infection is believed to be meat-and-bone meal contaminated with a protein called abnormal prion.

Several measures have been made to prevent the spread of BSE and infection to humans. One example is the incineration of meat-and-bone meal and its disposal in landfills. Another solution developed is the decomposition of abnormal prions by the incineration of meat-and-bone meal at a predetermined high temperature. If incineration is carried out in such a manner as to satisfy the above bone ash fertilizer manufacturing standards, there is a high possibility that the incinerator will be damaged. Furthermore, meat-and-bone meal contain a phosphorus component as calcium phosphate, and such a phosphorus component is known to deteriorate the strength of some materials that are used for the gasification and combustion process. It is also added that, in this kind of operation, the temperature of the meat-and-bone meal and bone ash during combustion and the flame at that time may differ greatly.

The document JP2007223865 discloses an apparatus for manufacturing a bone ash fertilizer under incineration conditions for utilizing meat-bone powder as a bone ash fertilizer and the manufacturing of the bone ash fertilizer.

The document JP2004239470 discloses a combustion method for waste materials such as meat debris related to BSE or bone-meal feed having less mixed bones, giving entire incinerating treatment thereto massively, safety and efficiently without blocking a supply line.

None of the previous documents present a solution that is capable of providing a full treatment of meat-and-bone meal which will result in safe ashes that can be used for the manufacture of fertilizers and simultaneously, provide energy.

These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.

GENERAL DESCRIPTION

The present disclosure relates to a method for processing meat-and-bone meal using a hydrogen enriched gas (Syngas), which makes the method more efficient and cost effective. Furthermore, the method results in the destruction of the BSE. With this method, a high amount of energy and ashes is obtained that can be further used for other applications such as fertilizers.

The present invention relates to a method for processing meat-and-bone meal for obtaining ashes, comprising the following steps:

• • feeding a catalytic fluidised bed gasifier with a meat-and-bone meal and an orthosilicate with a gas stream comprising oxygen, for obtaining a synthetic gas stream and ashes, wherein the catalytic fluidised bed gasifier is set at a temperature from 400° C. to 1000° C.;
  • grinding the obtained ashes;
  • feeding a thermal boiler with the ground ashes, the obtained synthetic gas, and a gas stream comprising oxygen for separating the ashes from the orthosilicate;
  • wherein the thermal boiler is at a temperature from 600° C. to 2000° C.; and
  • collecting the separated ground ashes.

This method is highly efficient for obtaining ashes and also energy. With 100 Kg of meat-and-bone meal, approximately 20 Kg of ashes is obtained.

In an embodiment, the gas stream is air or pure oxygen. In various implementations, the gas stream can be with or without steam, particularly, air with or without steam and oxygen with or without steam.

In an embodiment, the synthetic gas stream is a hydrogen enriched gas.

In an embodiment, the catalytic fluidised bed gasifier is fed with a water steam.

In an embodiment, the gas stream comprising oxygen is an air stream, typically a fresh air stream, or an oxygen stream.

In an embodiment, the process further comprises the step of feeding a cyclone with the synthetic gas of the catalytic fluidised bed gasifier for obtaining fine ashes.

In an embodiment, the process further comprises the step of feeding the thermal boiler with the fine ashes obtained in the cyclone.

In an embodiment, the thermal boiler is further fed with an amount of synthetic gas. Preferably the amount of synthetic gas is in a range of 8200 to 24000 m³/h; in some implementations, the amount of synthetic gas is, preferably in a range of 9000 to 20000 m³/h, and in other implementations the amount of synthetic gas is more preferably in a range of 10000 to 15000 m³/h.

In an embodiment, the process further comprises the step of feeding a silo with the fine ashes from the thermal boiler.

In an embodiment, the reactor is at a pressure from 90 kPa to 110 kPa. In some implementations, the reactor pressure is in a range preferably of 99 kPa to 103 kPa; in still other implementations the reactor pressure is in a range of preferably 99325 to 102325 Pa. In certain implementations the reactor pressure can be set more narrowly and more preferably between 99900 to 101525 Pa, or in some case more preferably between 100100 to 101225 Pa. The pressure is at sea level.

In an embodiment, the catalytic fluidised bed gasifier is at a temperature from 450° C. to 980° C. in some implementations the temperature of the catalytic fluidised bed gasifier is more preferably in a range of 730° C. to 850° C.

In an embodiment, the grinding of the ashes is made in a mill, such as a hammermill. Preferably the diameter of the screener of the mill is from 0.250 mm-2000 mm.

In an embodiment, the thermal boiler is at a temperature from 750° C. to 1500° C. In some implementations the thermal builder is at a temperature ranging more preferably from 850° C. to 1050° C.

In an embodiment, the orthosilicate is selected from Olivine, Dolomite, Alkaline metal, Nickel, or their mixtures

In an embodiment, the orthosilicate size is from 50 to 2000 μm. In some implementations, the orthosilicate size is in a range of preferably 55 to 1500 μm; in other implementations the orthosilicate size is in a more preferable range of 60 to 1400 μm. In further implementations, the orthosilicate size is in a more preferable range of 63 to 710 μm. The amount of orthosilicate depends on the granulometry of orthosilicate, gasifier diameter and the operation conditions.

In an embodiment, the height of fluidising bed solids of orthosilicate is from 1 m to 5 m.

In an embodiment, the process further comprising the step of feeding a buffer with the ground ashes for retaining the ground ashes before the feeding of the thermal boiler.

In an embodiment, the amount of ground ashes obtained is 20-25% (wt/wt_{meat-and-bone meal}).

In an embodiment, the dimension of the ground ashes is less of than 3 mm. In some implementations, the dimension of the ground ashes is in a preferable range of 0.5 to 1 mm. In other implementations, the dimension of the ground ashes is in a more preferable range of 0.6 to 0.8 mm. Measurements of the ashes can be made by Microscopy, e.g., Optical or Electron, laser diffraction, dynamic light scattering (DLS), sedimentation methods, image analysis, sieve analysis. The method used herein was microscopy.

In an embodiment, the dimension of the fine ashes is from 0.5 to 5 micrometres. Measurement of the ashes can be made by Microscopy-Optical or Electron, laser diffraction, dynamic light scattering (DLS), sedimentation methods, image analysis, sieve analysis. It was measured by microscopy.

The present disclosure also includes ashes obtained by the disclosed method for processing meat-and-bone meal to obtain ashes.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

FIG. 1: Schematic representation of an embodiment of the method for processing meat-and-bone meal.

FIG. 2: Schematic representation of an embodiment of the method for processing meat-and-bone meal.

FIG. 3: Flow chart of an embodiment of the method for processing meat-and-bone meal.

DETAILED DESCRIPTION

The present invention relates to a method for processing meat-and-bone meal for obtaining ashes, comprising the following steps:

• • feeding a catalytic fluidised bed gasifier with a meat-and-bone meal and an orthosilicate with a gas stream comprising oxygen, for obtaining a synthetic gas stream and ashes, wherein the catalytic fluidised bed gasifier is set at a temperature from 400° C. to 1000° C.;
  • grinding the obtained ashes;
  • feeding a thermal boiler with the ground ashes, the obtained synthetic gas, and a gas stream comprising oxygen for separating the ashes from the orthosilicate, wherein the thermal boiler is at a temperature from 600° C. to 2000° C.; and
  • collecting the separated ground ashes.

For better results, a catalyst is added to speed-up the reaction, such as orthosilicate. In the fluidised bed reactor, there is thermal contact between the biomass, namely the meat-and-bone meal, and the orthosilicate.

In an embodiment, the orthosilicate recirculates from the reactor to extract/degrade the fine ashes and is introduced again to the reactor jointly with the catalyst. Preferably, the orthosilicate is selected from Dolomite, Alkaline metal, Olivine, Nickel or their mixtures.

For better results, the ashes from the reactor are ground or crushed in the mill so that the ashes with a higher dimension will be totally burned in the next step, namely, in the thermal boiler. Also, the griding of the ashes enables the catalyst to be removed from the ashes.

In an embodiment the thermal boiler burns the synthetic gas and the ashes are obtained from the reactor. The thermal boiler burns the organic material that is still present in the ground ashes and also enables the amount of chlorides to be kept at a low level on the ground or fine ashes.

In an embodiment, the process further comprises the step of feeding a cyclone with the synthetic gas of the reactor for obtaining fine ashes.

In an embodiment, the process further comprises the step of feeding the thermal boiler with the fine ashes obtained in the cyclone.

In an embodiment, the process further comprises the step of feeding a silo with the fine ashes from the thermal boiler and decanting the fine ashes.

In an embodiment, the process further comprises a previous step of dehydrating the meat-and-bone meal before feeding the reactor.

In an embodiment, the reactor is at a pressure from 99325 to 102325 Pa. In some embodiments, the reactor pressure is in a preferred range of 99900 to 101525 Pa. In other implementations, the reactors is in a more preferred range of 100100 to 101225 Pa. These pressures allow enable output of the syngas from gasifier.

In an embodiment, the reactor is at a temperature from 450° C. to 950° C. In some embodiments, the reactor is at a more preferable temperature of 720° C. to 870° C.

In an embodiment, the reactor is a gasification reactor. In the gasification reactor a synthetic gas with H₂ and CO is obtained.

In an embodiment, the gasification reactor is a fluidised bed gasification reactor. Preferably the fluidised bed is in counter-current.

In an embodiment, the thermal boiler is at a temperature from 750° C. to 1500° C. In some implementations, the thermal boiler is at a more preferable temperature of 850° C. to 1050° C.

In an embodiment, the method comprises an air-water exchanger for the production of water steam in the boiler and an air/air exchanger to recover the heat from the combustion gases to heat the air of the reactor.

In an embodiment, the process further comprises the step of feeding a buffer with the ground ashes for retaining the ground ashes before the feeding the thermal boiler.

In an embodiment, the amount of ground ashes obtained is from 20 to 25% (wt/wt_{total of meat-bone meal}).

Ashes are obtained by the method for processing meat-and-bone meal to obtain ashes. The ashes can be used in several applications such as agriculture.

FIG. 1 shows a schematic representation of an embodiment of the method where: 1 represents the wet biomass input; 2 represents an output of dehydrated biomass, preferably the meat-and-bone meal; 3 represents dry biomass storage silo; 4 represents exit of biomass from the silo to be directed to the gasification reactor; 5 biomass input of the gasification reactor; 6 represents catalyst inlet; 7 represents air; 8 represents water vapour; 10 represents H₂/CO Synthetic gas outlet; 11 represents air; 12 represents water steam; 13 represents an ash output; 14 represents a mill-entrance; 15 represents a crushed/micronized ash output; 16 represents an input for the ground ash buffer; 17 represents an ground ash output; 18 represents an inlet for synthetic H₂/CO gas entering in the cyclone filter; 19 represents synthetic gas outlet from the cyclone filter; 20 represents an exit of the fine ash from the cyclone filter; 21 represents an inlet for storage of fine ash and 22 represents a fine ash outlet to the thermal oxidiser.

FIG. 2 shows a schematic representation of an embodiment of continuation of the method where 23 represents synthesis Gas Inlet H₂/CO; 24 represents entry of evaporates; 25 represents an entry of natural gas; 26 represents an air; 27 represents an injection of fine plus ground ash; 28 represents the thermal boiler suitable for operation with Synthetic Gas; 29 represents a Temperature control >=850° C.; 30 represents ground ash output; 31 represents an exit of combustion gases; 32 represents an inlet to the silo to capture the fine ash, which can be used for a P-phosphorus rich fertilizer manufacturing process; 33 represents an escape; 34 represents the fine ash output; 35 represents the chimney entrance; 36 represents the exit of gases to atmosphere; and 37 represents the atmosphere.

FIG. 3 shows a flow diagram of an embodiment of the method for processing meat-and-bone meal using the system components and arrangement discussed above. In a first step 100 a fluidized bed gasifier is fed with meat-and-bone meal and orthosilicate, and with a gas stream to obtain a synthetic gas stream and ashes. In a following step 110, the ashes are ground, for example in a mill. In step 120, a thermal boiler is fed with the ground ashes, the obtained synthetic gas, and a gas stream including oxygen to separate the ashes from the orthosilicate. The separated ashes are collected in step 130. In the depicted embodiment, after the ashes have been collected a cyclone is fed with the ashes and synthetic gas from step 110, and fine ashes are output form the cyclone in step 140. In step 150, the thermal boiler is fed with the fine ashes produced by the cyclone.

The following pertains to the ash characterization.

In an embodiment, the ash content is depending on the ash temperature. The ash content at 750° C. is 18.8 wt.-% (water free), at 850° C. it is 18.62 wt.-%. The ash content decreases with increasing ash temperature due to volatilisation of components like carbonates.

In an embodiment, the sulphur content of 0.66 wt.-% in total splits up into 0.02 wt.-% of ash sulphur and 0.64 wt.-% of combustible sulphur.

The calorific value is determined by burning the sample with oxygen in a bomb calorimeter. The higher heating value is a calculated quantity. The higher heating value (HHV) and the lower heating value (LHV) determined for the animal meal sample are listed below in Table 1, being ar: the sample as received; wf: water free biomass:

The water free biomass sample is a sample that was dried in a dryer.

The ash melting behaviour is determined by optical tracking of changes in form of a pressed pellet of sample ash. At characteristic form changes, the temperature is noted (e.g. spheric temperature). The melting behaviour was determined under oxidizing as well as reducing temperature. The 550° C. ash showed optical changes at approximately 880° C. (oxidizing atmosphere) and 960° C. (reducing atmosphere). For both atmospheres, no characteristic changes could be observed up to 1,592° C. (maximum temperature of the used lab equipment).

To gain insights of the chemical composition of mineral phases and the sulphur species distribution, an x-ray diffractometry was carried out. The results are shown in Table 2.

The term “comprising” whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above described embodiments are combinable.

The following claims further set out particular embodiments of the disclosure.