GB2629365A - Improved apparatus and methods for treating waste - Google Patents

Abstract

An apparatus 10 for treating material, e.g. slurry or damp flowable solids, comprises: a material holding chamber 20; a mixer 22 to mix material in the holding chamber; a material delivery mechanism 30, e.g. pump, for delivering the material from the holding chamber to a treatment chamber 40; the treatment chamber having a first end to receive the material and a second end to allow egress of solids, and further comprising a gas inlet port and a gas outlet port for flowing gas through the treatment chamber. At least one heated rotating paddle dryer 50, each having a plurality of discrete paddles (54, 56, Fig. 2B), heats and mixes material as it travels through the treatment chamber. A condenser 60 condenses vapours extracted from the chamber. A separator 80 separates extracted gases and condensed liquids. A vacuum pump 70 creates a vacuum in the treatment chamber and in a gas-circulation circuit from the treatment chamber via the condenser and separator back to the treatment chamber. A fan 90 circulates extracted gas/vapours via the gas-circulation circuit. The material may be distillery or dairy or fish hatchery by-products, sewage sludge, or spent coffee grounds. A method for treating material is also described.

Description

Improved Apparatus and Methods for Treating Waste

Field of the Invention

The present invention relates to method(s), apparatus and use(s) of apparatus for treating materials such as waste products and by-products of industrial processes e.g. slurries comprising solids and liquids, e.g. comprising solids and water, or solids, oil(s), and water, or damp flowable solids e.g. damp sands.

Background

Disposal of waste from industrial sites can be complicated and expensive not least because of high liquid content of the waste, e.g. water and/or oil. The volume of waste to be disposed of is therefore high. Industries affected by this include the onshore and offshore oil industries, the fish industry (e.g. hatchery, lifetime and processing stages), the milk industry, the distilling industry e.g. for whisky, the beverage. e.g. coffee. industry e.g. for disposal of waste damp grounds), as well as the more obvious sewage industry. Furthermore, contaminants may need to be removed before the waste can be landfilled.

Various treatment technologies exist, but are often characterised by large plant requirement, too big or complex for existing sites. Often existing waste processing plant must be adapted to a particular industry and/or particular site and this is time consuming and expensive. Furthermore, often existing plant has higher energy requirements than is desirable. Some lower energy solutions are available e.g. W02017/153733 IMRIE from the present applicant. Nevertheless, further improvements are desirable in terms of wider applicability to a variety of different industries and waste products without significant adaption. Further improvements are desirable in terms of ongoing reduction in energy requirements, and/or reduction in size, and/or applicability to different waste products sites in the same of different sectors each with their own requirements in terms of products to be processed etc., and so on.

There is an ongoing need for the development of alternative technology with even lower operating costs. In the many industries, a solution would be a modular mobile plant which could be deployed to treat the waste at source, splitting it into one or more volumetrically reduced waste portion(s), typically dry solid portion(s), which may be hazardous, and one or more inert portion(s), typically liquid(s) e.g. water, and possibly oil.

Indeed, the problems of improved operation of more recently developed lower energy solutions remains. Capital cost is one, and reduced capital cost is desirable to make the apparatus more accessible. Wider applicability is also a challenge. It is desirable that the same apparatus could be used in a wide variety of industries, and scenarios. Thus, instead of each industry having its own bespoke solution, a common apparatus could be used in several different industries. If this were possible, and the size of the apparatus were controlled, this could be used then transported between sites in the same industry or between sites of different industries.

The technical and engineering challenges of producing plant apparatus and associated processes, powerful, yet efficient enough to have a useful volumetric output, but also preferably small enough to be mobile, and flexible enough in operation to be used in different sites (with different compositional and volumetric requirements) and in different industries (with different compositional and volumetric requirements) without designing and building different bespoke apparatus each time are significant.

Statements of the Invention

In a first aspect of the invention there is provided an apparatus for treating material (such as material comprising slurry (a mixture of solids and liquids) and/or solids (e.g. damp flowable solids)), the apparatus comprising: a holding chamber (e.g. a holding tank) for starter material (optionally configured to mix and/or heat material to be treated to form a starter material); a material delivery mechanism (e.g. pump for pumping, or auger for conveying) for delivering starter material from the holding chamber to a treatment chamber; the treatment chamber having a first end configured to receive starter material to be treated and a second end configured to allow egress of solids, and being configured to hold a vacuum, and further comprising a gas inlet port and a gas outlet port for flowing gas through the treatment chamber (e.g. within internal free space within the treatment chamber, preferably under vacuum); at least one heated material dryer configured to heat and mix material (e.g. initially, especially near the first end, starter material, later, especially further along, at least partially treated material) as it travels through the treatment chamber in a direction from the first end towards the second end; a condenser configured to receive extracted gas and vapour (typically air and water/oil vapour) from the chamber and condense the vapour (e.g. at least part or most or substantially all the vapour) into liquid form; a separator configured to separate extracted gases and condensed liquids (e.g. water or water and oil); a vacuum pump configured to create a vacuum in the treatment chamber and in a gas circulation circuit from the treatment chamber via the condenser and separator back to the treatment chamber; a gas circulator (e.g. fan) configured to circulate extracted gas and vapours (e.g. as yet uncondensed vapours) via the gas circulation circuit from the treatment chamber to the condenser and separator and back into the treatment chamber; and further comprising: a mixer configured to mix starter material in the holding chamber (ready for delivery to the treatment chamber); the at least one heated material dryer comprising one or more heated rotating paddle dryers each having a plurality of (e.g. two or more, preferably several) discrete paddles (e.g. which cooperate with each other along a paddle dryer and/or from one paddle dryer to the next, to break up the material being processed to assist in drying, and preferably also retain at least some flowability so that material is able to move laterally along the treatment chamber from the first end towards the second end, and vice versa).

The holding chamber may be heated e.g. by one or more heating jackets and/or heating elements. The one or more heating jackets and/or heating elements may be electrically heated, or more preferably may be heated by thermal liquid such as heated water. In a preferred embodiment, the holding chamber is heated by a heating jacket through which a heated thermal liquid such as heated water can circulate.

The mixer may comprise one or more mixing elements within the chamber.

The holding chamber may be open, or covered over, or enclosed so as to be air and water tight.

The treatment chamber is preferably enclosed (air and water tight).

The condenser may comprise a cooling water circuit to draw in cold water, and to cool gases and vapours in the condenser, and to deliver heated water (e.g. resultant heated water) to a hot water outlet pipe; and the hot water outlet pipe may be configured to deliver hot water to the holding chamber (e.g. to a heating jacket) from the condenser to pre-heat starter material in the holding chamber (ready for delivery to the treatment chamber).

In this way, instead of the apparatus producing hot cooling water from the cooling water circuit of the condenser, which then becomes another hard to dispose of (e.g. locally on site) waste product, the apparatus produces cooler water, e.g. room temperature e.g. 15-25°C, typically around 20 °C, which can be more easily disposed of. Furthermore the initial starter material is heated to a similar temperature to the now cooled condenser liquid e.g. before entering the treatment chamber, e.g. 15-25°C, so around room temperature (around 20°C).

In the improved apparatus of the invention, the consistency of material delivered for treatment in the treatment chamber can be improved, e.g. rendered more consistent, by mixing, and preferably also pre-heating, such that, together with the increased applicability of the selected dryer, the paddle dryer with discrete paddles, to a wider range of material types, means that a wider range of starter materials can be considered (with a wider range of viscosities, consistencies, granularities, particle size, range of particle size, % liquid by weight, temperatures and so on) and so be treated effectively, all with a single apparatus with little if any further adaption.

Few, if any, other adaptions, other than process conditions, need to be made with this improved apparatus. Further, in one or more embodiments of this or other aspects (e.g. the method) of the invention, such process conditions can be provided easily.

One adaption which may be put in place in one or more embodiments is the use of a pump for pumping slurries as a material delivery mechanism, or alternatively an auger for delivering flowable solids (e.g. damp flowable silts, sands and grains) as a material delivery 20 mechanism.

In some embodiments, the material is pushed along from the first end to the second end by the addition of more material near the first end, and the extraction of material from the second end, freeing up space within the chamber near the second end for material within the chamber to move into.

In one or more embodiments, the rotating paddle dryer comprises heated paddles. Typically this may be a rotating hollow paddle dryer.

The one or more heated paddle dryers may comprise one or more series of discrete paddles, adjacent paddles having gaps therebetween (e.g. in a longitudinal direction).

The series of paddles may comprise one or more rows of paddle portions having gaps therebetween (e.g. in direction, e.g. more or less in a plane, transverse to longitudinal direction). A paddle portion may extend over.s 180 degrees, or 270 degrees, or.s 360 degrees around a longitudinal axis of rotation.

The one or more heated paddle dryers may be configured not to draw material along through the chamber in a direction from the first towards the second end.

The one or more heated paddle dryers may be configured to draw material along through the chamber in a direction from the first towards the second end.

The paddles (e.g. at least some, most, substantially all) of the one or more rotating paddle dryer may be configured to provide an impetus to the material to convey it along from a first end to a second end. Thus, the rotating paddle dryer may be referred to as a rotating paddle conveyer. This configuration may be specially shaped paddles, as one example, a paddle of increasing thickness towards its base on the side towards the second end, so as the paddle is driven into the material when it rotates, it not only breaks material apart it imparts lateral motion to some of the material towards the second end. Indeed, the paddles may have at least one side panel with a surface that forms a screw thread with a corresponding surface on an adjacent paddle to operate as a conveyer but this is not necessary; the shape of the side panels of the paddles may simply be adapted to urge the material along without forming screw thread. Thus, the shape of the external surfaces of the paddles (e.g. facing the second end) may also form a discontinuous screw thread but this is not necessary to achieve the effect of lateral motion from the first to the second end.

The configuration may comprise corresponding surfaces of one side of the paddles (e.g. at least some, most, substantially all) of the one or more rotating paddle conveyors forming a discontinuous screw thread. The paddles may have a leading surface shaped to urge material laterally along from the first to the second end.

In these or other embodiments, the paddles may have a wedge-shaped cross-section e.g. having a thinner first, typically leading, edge (e.g. a substantially, or generally, radially extending edge) of the paddle leading to a thicker second, typically trailing, edge (e.g. a substantially or generally radially extending edge) of the paddle. The paddles can be used in reverse, with the thicker edge leading but this is less preferred. Typically, the paddle rotates so that its thinner first edge (a leading edge) engages the material first, the material being forced apart as it slides over the side panels of the widening wedge-shaped paddle. The side panels of each paddle are typically smooth and very generally planer, although these may be curved. The outer edge of each paddle, where the two side panels meet, is preferably curved, more preferably circular (if it lies in 2 dimensions) or spiral (if it lies in three dimensions).

The paddles or paddle portions where provided, may have a wedge-shaped cross-section e.g. having a thinner first edge of the paddle leading to a thicker second (trailing) edge of the paddle.

The one or more rotating paddle dryers may comprise hollow thermally-heated rotating paddle dryers. Preferably this or these are configured to be heated by thermal fluid, preferably thermal oil. Oil is preferably as it provides a greater range of temperatures than water, given its higher boiling point than water. The oil may be heated by a boiler. The boiler may be powered by existing fuel sources, or by the dry solid waste material produced by the apparatus, of course this will depend on the material being processed as to whether this is

suitable.

Preferably, the paddles may extend around up to 180 degrees (e.g. around a longitudinal axis of rotation) of the rotating paddle dryer, or up to 270 degrees, or up to 360 degrees of an axis of rotation. Preferably the paddles are hollow, preferably in fluid communication with a hollow central conduit (also known as a shaft) lying along an axis of rotation.

Preferably. paddles (e.g. at least some, most, substantially all) or paddle portions (e.g. at least some, most, substantially all) of the one or more rotating paddle dryers extend s 180 degrees, or s 270 degrees, or s 360 degrees around their respective longitudinal axis (e.g. so as to provide one or more preferably several gaps).

At least two intermeshing rotating paddle dryers may be provided. The at least two intermeshing rotating paddle dryers may be self-cleaning.

Each of the one or more paddle dryers may comprise two or more rows of paddles spaced apart along a central hollow conduit (or shaft), paddles of a first row of paddles alternating (e.g. in a longitudinal direction) with paddles in a second row, neighbouring paddles in each respective row extending in a generally, or substantially, transverse directions (optionally, overlapping about their respective peripheries).

Alternatively, only one row of paddles may be provided on each of the one or more paddle dryers. In this case, the paddles preferably extend 270 degrees or more, even up to 360 degrees, about their axis of rotation. This circumferential extent of each paddle assists in preventing material moving back towards the first end, whilst their discrete nature permits some backwards flow.

By providing two rows of paddles along each paddle dryer, each neighbouring pair of paddles (one from each row on the same central shaft) can provide an overlap with its neighbour about its peripheral extent. For example, each of a neighbouring pair of paddles (one from each row) can provide an overlap with its neighbour if each extends circumferentially nearly 180 degrees, preferably at or over 180 degrees, e.g. just over 180 degrees. Thus, looking longitudinally along the conduit, an overlap between one paddle of a pair and its neighbour is provided, restricting the passage of material backwards. This provision of discrete yet overlapping paddles facilitates material being prevented from moving back toward the first end to any great extent, and the break-up of the material more frequently, opening up a greater surface area of material to evaporation. Further this provides a significant amount of heated paddle surface area to engage the material within the chamber.

Thus providing discrete paddles of suitable angular extent, typically large angular extent, a large heat exchange surface area and careful control of material within the chamber is provided. There is no need to provide a steeper incline, so material moves more controllably along the treatment chamber.

Whilst each paddle is discrete, the separation from one to the next may not be complete. For example, a pair of opposing paddles on one paddle dryer, may be provided as a general figure of eight configuration with two discrete paddle portions separated by a narrow neck providing a gap in between so that their outer periphery is continuous rather than broken. It is sufficient that there is a narrowing of radially extent, at least in part from one paddle portion to the next.

The number of paddles on each paddle dryer per meter length may be between 2 and 12, and is preferably between 3 and 6. Thus, where two intermeshing paddle dryers are provided, there may be twice this number per meter length.

Preferably the paddles are equi-spaced. Preferably the paddles are closely spaced from one to the next, e.g. so that the gap between each pair of neighbouring paddles in the same row is of the same order or about the same or just larger than the thickness of one paddle.

A first temperature gauge (T3) for measuring the temperatures of extracted gas and vapour may be provided at (e.g. near or adjacent) a gas entrance to the condenser.

A second temperature gauge (T2) for measuring the temperatures of extracted gas and vapour may be provided at (e.g. near or adjacent) the gas outlet of the treatment chamber.

A control unit may be provided, configured to maintain gas and vapour at the entrance to the condenser (T3) at a temperature of 100°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C, or more preferably 120°C to 140°C. The control unit may be configured to maintain gas and vapours at the exit of the treatment chamber (T2) at a temperature of 100°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C, or more preferably 120°C to 140°C. This range of temperatures on exit from the treatment chamber, or more preferably on entrance to the condenser, assists in preventing condensation within the conduit, typically a pipe, from the treatment chamber to the condenser. By preventing condensation here, the design of the apparatus can be simplified.

The conduit may thus be provided at any angle, e.g. even an upward angle, much like chimney, from the chamber to the entrance to the condenser without any risk of vapours condensing in the conduit and running back down to the treatment chamber. This avoids liquid running back down into the treatment chamber, and the potential resultant inefficiency of repeated evaporation of the same liquid, whilst providing for variation in apparatus configuration.

Further, this range of temperatures in the extracted gas and vapour provides a wider range of operating temperatures for the chamber for drying a wide range of waste materials. Nevertheless, the temperatures are not so high as a flashpoint of the expected vapours, again for a wide range of expected applications in differing industries. Preferably during use, the temperature of the vapours exiting the chamber are at a temperature less than a flashpoint of any components of the slurry.

A temperature gauge (T4) may be provided at (e.g. near or adjacent) the exit of the condenser for measuring the temperatures of cooled extracted gases and vapours.

A temperature gauge (T1) may be provided at (e.g. near or adjacent) the material entrance to the treatment chamber condenser for measuring the temperature of starter material (e.g. pre-heated starter material).

A temperature gauge (T5) may be provided at (e.g. near or adjacent) the material exit to the treatment chamber for measuring the temperature of treated solids on exiting the chamber.

One or more sight gauges may be provided e.g. between the condenser and the separator and/or between the condenser and the vacuum pump.

The apparatus may be configured to support a vacuum in the treatment chamber in one of the following ranges (within expected tolerances of construction and operation): bar, <1.9 bar, <_0.7 bar, C.6 bar, <_0.5 bar, 0.2 to 0.9 bar, 0.25 to 0.75 bar, 0.4 bar to 0.6 bar, 0.4 bar to 0.6 bar. The apparatus may be configured to support a vacuum in the treatment chamber at one of the following values (within expected tolerances of construction and operation): 0.9 bar, 0.8 bar, 0.7 bar, 0.6 bar, 0.5 bar, 0.4 bar.

The gas inlet port and gas outlet port may be configured so that vapours and gas flow in a direction generally, or substantially, in the same general direction of movement of slurry and/or solids drawn though the treatment chamber from the first end towards the second end. The gas inlet port may be at or near the first end of the treatment chamber and /or the gas outlet port is at or near the second end of the treatment chamber. Preferably, the apparatus is configured to support flow rate of gas of: m/s, or <1.8m/s, or.s0.6m/s, or.s 0.5m/s, or.s 0.4m/s.

Preferably, the one or more rotating paddle dryer has an adjustable incline with respect to the horizontal within the chamber, preferably rising upwardly from the first end to the second end. Alternatively or in addition, the treatment chamber has an adjustable incline with respect to the horizontal, preferably rising upwardly from the first end to the second end. Typically, the treatment chamber and paddle dryer are both inclined at the same predetermined angle with respect to the horizontal.

Preferably, a solids outlet port is provided at or near the second end of the treatment chamber. Preferably, the solids outlet port comprises a rotary valve. Preferably, the chamber comprises a material inlet port at or near the first end of the treatment chamber, e.g. configured to receive material in a continuous or quasi-continuous manner.

In a further aspect of the invention there is provided a method for treating material (such as material comprising slurry (a mixture of solids and liquids) and/or solids (e.g. damp flowable solids)), using an apparatus as described herein, the method comprising: holding starter material in a holding chamber (optionally mixing and/or heating material to be treated to form a pre-mixed and/or preheated starter material); delivering starter material from the holding chamber to a treatment chamber; receiving starter material to be treated at a first end of the treatment chamber having and egressing solids at a second end, flowing gas through the treatment chamber from a gas inlet port to a gas outlet port for (e.g. within internal free space within the treatment chamber, preferably under vacuum); using a vacuum pump to provide a vacuum in the treatment chamber, and in a gas circulation circuit from the treatment chamber via the condenser and separator back to the treatment chamber; using a gas circulator (e.g. a fan) to circulate extracted gas and vapours (e.g. as yet uncondensed vapours) via the gas circulation circuit from the treatment chamber to the condenser and separator and back into the treatment chamber treating material using at least one heated material dryer configured to heat and mix material (e.g. initially, especially near the first end, starter material, later, especially further along, at least partially treated material) as it travels through the treatment chamber in a direction from the first end towards the second end; receiving extracted gas and vapours from the chamber into a condenser (typically air and water/oil vapours) and condensing the vapours (e.g. at least part or most or substantially all the vapours) into liquid form; using a separator to separate extracted gases and vapours from condensed liquids (e.g. water or water and oil); and further in which: using a mixer to mix starter material in the holding chamber (ready for delivery to the treatment chamber); the at least one heated material dryer comprising one or more heated rotating paddle dryers each having a plurality of (e.g. two or more, preferably several) discrete paddles, and using the rotating paddle dryer to treat the material (e.g. which cooperate with each other along a paddle dryer and/or from one paddle dryer to the next, to break up the material being processed to assist in drying, and preferably also retain at least some flowability so that it is able to move material laterally along the treatment chamber from the first end towards the second end).

The method may further comprise using the condenser to draw in cold water, and to cool gases and vapours in the condenser, and to deliver heated water (e.g. resultant heated water) to a hot water outlet pipe; and delivering hot water via the hot water outlet pipe to the holding chamber from the condenser to pre-heat starter material in the holding chamber (ready for delivery to the treatment chamber); The method may comprise maintaining (e.g. controlling the apparatus such that) gas and vapours at the entrance to the condenser (T3) is at a temperature of 100°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C or more preferably 120°C to 140°C. The method may comprise maintaining (e.g. controlling the apparatus such that) gas and vapour at the exit of the treatment chamber (T2) is at a temperature of L100°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C or more preferably 120°C to 140°C.

The method may comprise providing a vacuum in the treatment chamber in one of the following ranges (within expected tolerances of construction and operation): Si bar, 50.9 bar, 50.7 bar, 50.6 bar, 50.5 bar, 0.2 to 0.9 bar, 0.25 to 0.75 bar, 0.4 bar to 0.6 bar, 0.4 bar to 0.6 bar. The method may comprise providing a vacuum in the treatment chamber at one of the following values (within expected tolerances of construction and operation): 0.9 bar, 0.8 bar, 0.7 bar, 0.6 bar, 0.5 bar, 0.4 bar.

The method may comprise treating material in the treatment chamber such that the solids are substantially dry before removal.

The method may comprise controlling the temperature of the gas and vapour exiting the chamber to be less than a temperature of a flashpoint of any of the ingredients of the material. The method may be controlled so that the components of the material are not changed chemically.

The method may comprise: drawing gas through the chamber from the gas inlet port near a first end to the gas outlet port near the second end, optionally in which the gas is air. Thus, preferably, gas is drawn through the chamber in a direction generally or substantially the same as the direction of movement of material through the treatment chamber from the first end to the second end.

The method may comprise maintaining the flow rate of gas through the chamber of: 5_1m/s, or 0.8m/s, or 5_0.6m/s, or 0.5m/s, or 0.4m/s.

The method may comprise selecting, configuring, and controlling one or more parameters from the following: pressure within the treatment chamber; -retention time of material within the treatment chamber; - temperature of incoming material; temperature of extracted vapour(s); flow rate of gas through the chamber; temperature of re-circulated gas following a vapour condensing step; - temperature of the heated material conveyor; temperature of the solid(s)on egress; temperature of the thermal oil inlet; - temperature of thermal oil outlet; speed of rotation of the one or more paddle dryers; cro of solids by mass of incoming material; rate of ingress of incoming material; moisture level of solid(s) on egress; - incline of the chamber; controlling the vacuum to be within a pre-determined value; controlling the level of material on ingress so that solid(s) on egress have a desired moisture or dryness level, The method may comprise controlling the temperature of exiting solids to be 125°C, or 120°C, or 110°C, or.S100°C, or.s90°C.

It is also preferred that the vacuum remains constant (e.g. within 5% or 10% of the desired value) i.e. the partial vacuum is well maintained.

Preferably, the gas is air. Preferably, in the method, gas is drawn through the chamber in a direction generally or substantially in the same the direction as movement of material through the treatment chamber from the first end to the second end.

Several embodiments of the invention are described and any one or more features of any one or more embodiments may be used in any one or more aspects of the invention as described above.

Brief Description of the Invention

The present invention will now be described, by way of example only, with reference to the following figures. The same reference numerals refer to the same features throughout the figures.

Figure 1A is a schematic diagram of an apparatus according to an example embodiment of the invention including a schematic, plan view of a paddle drier.

Figure 1B is a schematic end view of the paddle drier seen in the apparatus of Figure 1A.

Figures 2A and 2B are identical to Figures 1A and 1B, respectively, with additional labels.

Figures 3A to 3E are a series of tables in respect of different materials (Figure 3A distillery by-products, Figure 3B dairy by-products, Figure 3C sewage sludge, Figure 3D spent coffee grounds, Figure 3E fish hatchery by-products) detailing the various process conditions and results for the different materials, when using a prototype of the apparatus of the invention.

Figure 4A is a table showing analytical results from laboratory analysis for distillery byproducts (here a pot ale and draff mix from barley) illustrating the chemical oxygen demand (COD) in milligrams per litre, the pH, and the suspended solids (SS) in milligrams per litre, where available.

Figure 4B is a table illustrating analytical results for distillery by-products (here a spent wash from grain) illustrating the chemical oxygen demand (COD) in milligrams per litre, the pH, and the suspended solids (SS) in milligrams per litre.

Figure 5 is a table showing analytical results from laboratory analysis for the dairy byproduct whey illustrating the pH, the chemical oxygen demand (COD) in milligrams per litre, and the biological (or biochemical) oxygen demand (BOD) in milligrams per litre, prior to treatment using a prototype apparatus of the invention, of the condensate post-treatment using a prototype apparatus of the invention, and of the condensate post-filtering using a standard industry filter.

Figure 6A shows an image of whey prior to treatment, seen here as a cloudy liquid, Figure 6B shows an image of the condensate post-treatment, seen here as a clear liquid, and Figure 6C shows an image of the resultant solids post-treatment, seen as dry solids in the bottom of a bucket.

Detailed Description of the Invention

In the following description, the terms gas and vapour are used as per their common usage and can mean both the singular, as in a gas or vapour of a particular substance, and the plural, as in a combination of gases or vapours of different substances. Furthermore, as again in common parlance, gas is used to refer to those substances such as the gases of air which are in gaseous form at room temperature. Whereas the term vapour is used as in common parlance to refer to those substances which are typically in liquid or solid state at room temperature but a gas state above room temperature, or which coexist in both states.

Neither term is intended to be limiting unless the context dictates otherwise.

One or more temperature gauges (also known as temperature probes) are provided at various strategic points in the apparatus of the present invention and these are referred to as T1, T2, T3, T4, and T5. It will be understood by those skilled in the art that these labels T1, T2, T3, T4, and T5 can also be used to refer to the temperature measured by the respective temperature gauge, and it will be clear from the context which is intended.

In the following description, the term material is used to describe the slurries comprising solids and liquids, such as solids and water, or solids, oils and water, or damp, flowable solids, that are to be treated. Such materials may also be known as by-products or waste products from an industrial process and may also, on occasion, be referred to as a product, meaning such a by-product or waste product, from an industrial process. Nevertheless, such products which are to be treated in the apparatus of the invention, and/or in the method(s) of the invention, are input or starter materials to the apparatus or method(s) of the invention and, once treated, these become output or final materials, also known as end products, typically in the form of solids and liquids.

It will be understood by those skilled in the art that any dimensions, or any directions such as vertical or horizontal, or any measurements referred to in this application are within expected tolerances and limits for the waste processing industry and these terms should be construed with this in mind.

Turning now to the Figures, Figure 1A shows an apparatus 10 according to an example embodiment of the invention. Apparatus 10 comprises, in this preferred embodiment, a material holding chamber 20, here a material holding tank; a material delivery mechanism 30, here a pump; a treatment chamber 40 comprising a heated material dryer 50 within it; a condenser 60; a vacuum pump 70; a liquid separator 80, here a liquid separator tank; and an air blower 90, here an air fan.

Material to be treated is held in product holding tank 20, before being delivered by pump 30 to treatment chamber 40. Material being treated by treatment chamber 40 passes from a first end of treatment chamber 40 towards a second end of treatment chamber 40 along a heated material dryer 50, preferably a rotating paddle dryer 50. Rotating paddle dryer 50 may also function as a conveyor to transport material from the first end of treatment chamber 40 to the second. Extracted gas (in use, comprising gas, typically air, and vapour) are delivered to condenser 60 before being separated in separator 80. Vacuum pump 70 provides a vacuum throughout the apparatus 10 and fan 90 circulates exacted gas, typically air and vapours, around apparatus 10.

Figure 1B shows an end view of the treatment chamber 40 and paddle dryer 50, as will be described in more detail in relation to Figures 2A and 2B.

In more detail now, referring to Figures 2A and 2B, material holding tank 20 preferably comprises a mixer 22 for premixing of material within material holding tank 20. A valve 24 controls delivery of material from tank 20 into an input pipe 25 along which material is pumped by pump 20 and via e.g. a rotary valve 26 into treatment chamber 40 at a first end 44 of treatment chamber 40. The rotary valve 26 may be continuously open, or may be opened intermittently depending upon the level of material in the chamber. An arrow 28 indicates the path of starter material entering treatment chamber 40. Treatment chamber 40 is airtight as well as watertight to prevent escape of liquid and/or gases other than as specified within the apparatus 10 and to facilitate control of a slight vacuum within.

Treatment chamber 40 may be provided with a thermal jacket (not shown) in which thermal oil is circulated, for example via a thermal oil circuit 42. Thermal oil circuit 42 may have a relief valve 24 venting to atmosphere.

Within treatment chamber 40 is a heated material dryer 50, here a rotating paddle dryer comprising one or more series of paddles 54, 56. Rotating paddle dryer 50 is preferably hollow, e.g. along one or more central conduits 55 and/or throughout associated paddles 54, 56. A thermal oil circuit 52 provides heated thermal oil into the hollow conduit and paddles of paddle dryer 50.

Preferably, rotating paddle dryer 50 is also a conveyor with paddles 54, 56 arranged to provide a discontinuous screw thread to cause material to move, albeit slowly, from the first end 44 towards a second end 46.

One or more series of discrete paddles are provided, preferably two or more. Here, two series of discrete paddles 54, 56, form two series of interweaving paddles, a first series 54 on a first central conduit 55 and a second series 56 on a second central conduit 55. The conduits 55 which define a longitudinal axis of rotation of the paddles, are typically parallel to one another, and the paddles extend laterally away from this longitudinal axis.

In this example embodiment, two series of paddles are provided, one or more preferably each paddle in one series being spaced from its adjacent neighbours on the same conduit and having a longitudinally extending gap in-between. Thus, each paddle is spaced longitudinally from its neighbours (along central conduit 55). This allows paddles 54 on one conduit 55 to interweave with paddles 56 on a neighbouring conduit 55. Thus, as can be seen in Figure 2B, paddles 54 on a first conduit 55 alternate with paddles 56 on a second conduit 55, with a narrow gap 47 spacing these from one another in a longitudinal direction, around at least part of their circumference. In one or more embodiments, the alternating paddles in the first and second series, each on a respective conduit 55, are sized and shaped to engage with each another at at least one location, e.g. across a radius, to facilitate self-cleaning. Thus, gap 47 may vary circumferentially around each paddle and may fall to zero where these engage.

In preferred embodiments, paddles 54 and 56 have a wedge-shaped cross-section circumferentially around first central conduit 55. Preferably, the wedge-shaped cross-section provides a narrower leading edge, which is forced into the material upon rotation, and a wider trailing edge, which slowly forces the material apart. Some of the material is forced longitudinally towards the second end 46 and some (typically less) towards the first end 44. The wedge-shaped paddles, where provided, produce shear forces on the paddle surface and this keeps the paddles cleaner and contributing to a more efficient heat transfer.

In some embodiments, the side panel of a paddle (e.g. between the leading edge and the trailing edge) facing the second end 46 may have a shape which urges material in a preferential manner towards the second end 46. In some embodiments, the shape of this side panel may co-operate with corresponding side panels of other paddles in one series or in both series to urge material towards the second end 46. Typically, in this arrangement, the side panels form a discontinuous screw thread to urge material from one end to the next.

This is, however, not necessary but may be preferred.

Looking at the series of panels in more detail now, and particularly at Figure 2B, in some embodiments, the discrete paddles of one or more or each series, form two (or more) discrete paddle portions 54A and 54B, 56A and 56B.

In the example embodiment shown in Figure 2B, paddle portions 54A and 54B form a paddle 54 having a general figure of eight shape with two paddle portions 54A and 54B, one above central conduit 55 and one below (as seen in Figure 2B). Similarly, a second series of paddles 56 comprises a number of discrete paddles, preferably each formed in two paddle portions 56A and 56B, together forming a generally figure of eight-shaped paddle 56. Here, paddle portion 56A is to the left of central conduit 55 and paddle portion 56B is to the right of the central conduit 56 (as seen in Figure 2B).

Thus, each series of discrete paddles 54, 56 may comprise two or more rows of paddle portions, the first series comprising two rows of paddle portions 54A, 56A respectively, and the second series comprising two rows of paddle portions 54B and 56B.

Alternative arrangements of paddle portions may be considered, for example, generally Y-shaped with three discrete paddle portions, generally X-shaped with four discrete paddle portions, each forming respectively three or four rows of paddles on a respective conduit 55.

Between each paddle portion 54A, 54B or 56A, 56B is a gap, or bite, 57 through which material can flow in either direction, so in a direction from the first end 44 towards the second end 46, or from the second end 46 towards the first end 44. This arrangement facilitates mixing of the material in both directions throughout the process. Thus, material can traverse from the first end to the second end, but material can also traverse, e.g. under the effect of gravity, from the second end towards the first end.

Thus, as the paddles rotate about a central axis, e.g. lying along a centre of the central conduit 55, material can flow in both directions and, indeed, can be mixed so as to flow in both directions. This means that material does not travel solely in one direction from the first end towards the second end but, rather, partially treated material can be mixed with incoming material near the first end, and vice versa.

Typically, the dryer 50, and preferably the treatment chamber 40, for example as measured along a longitudinal axis, is at a slight angle to the horizontal. Typically, this angle may be anywhere from 1 to 15°, more preferably 3 to 10°, more preferably 3 to 5°. Typically, 3° may be used. Preferably, the treatment chamber 40 is in line with the paddle dryer 50 and so is at the same angle to the horizontal.

The path of the material is shown generally by arrows 28. In use, starter material e.g. prepared within holding tank 20, enters treatment chamber 40 near first end 44 via rotary valve 26 and dryer, e.g. dry, solid material exiting via a rotary valve 26 at a bottom of treatment chamber 40 into a solids outlet hopper (not labelled) and any gas (typically comprising air and vapour) exit via a gas outlet (not labelled) at the top of treatment chamber 40 into an outlet pipe 36, in the direction shown by arrow 38.

Series of paddles 54 and 56 typically rotate in opposing directions, one clockwise, the other anticlockwise, as seen in Figure 2B. When dry solids exit the chamber at second end 46 via rotary valve 26, and fresh starter material is introduced at first end 44, again typically via a rotary valve 26, impetus is provided to the material within treatment chamber 40 to move from the first end 44 to the second end 46 where space has been made available by the exiting material. Nevertheless, the provision of discrete paddles 54, 56, along with free space between the paddles and the chamber walls, and preferably also discrete paddle portions 54A, 54B, 56A, 56B interspersed with gaps 57, allows material to flow from the second end 46 towards the first end 44 at least to a small extent, encouraging mixing and drying. This can be seen in the asymmetric arrows 28, seen in the centre of treatment chamber 40, in Figure 2A. Thus, the addition of at least one bite or gap 57 within each discrete paddle 54, 56, preferably at least two to form two or more discrete paddle portions 54A, 54B, 56A, 56B, further enhances the slight flow of material from the second end to the first end. The overall effect of this is a continual mixing of partially treated material with freshly introduced material as well as the delivery of treated material near the second end 46.

Although provided here as paddle portions of a single discrete paddle, paddle portions 54A, 56A and 54B, 56B could indeed be provided as individual discrete paddles, either in line or slightly offset from one another.

A gear box G and a motor M drive the paddles of paddle dryer 50 to rotate.

Gas outlet pipe 36 is provided near second end 46 of treatment chamber 40. Gas outlet pipe 36 is in fluid communication with a free space 58 provided above paddles 54 and 56 within treatment chamber 40, at least near the second end 46 and, preferably, over most of the second half of treatment chamber 46. Thus, gas and vapour (liquid in gaseous form) can be extracted along gas outlet pipe 36.

A temperature gauge T1 is provided on delivery pipe 25 near first end 44 to measure the temperature of the starter material on entry to chamber 40.

A temperature gauge T2 is provided to measure the temperature of gas and vapour as these exit chamber 40.

A temperature gauge T3 is provided at the entrance to condenser 60 to measure the temperature of the extracted gas and vapour (typically air and vapour) entering the condenser. Typically, the condenser has a suitable incline (fall line) from its inlet to its outlet so that any liquid condensed within it runs towards its outlet at its second end and not back towards its first end.

Advantageously, the temperature of the extracted gas and vapour reaching the condenser is maintained at 100°C or above so that no, or virtually no, condensation occurs within gas outlet pipe 36. Indeed, it is helpful to have both temperature gauge T2 at the exit of chamber 40 and temperature probe T3 at the entrance to condenser 60 to facilitate the measurement of temperatures at both ends of gas outlet pipe 36 and for assisting in maintaining gas and vapour at the entrance to the condenser at a temperature of 100°C or more.

Temperatures at T3 the entrance to the condenser in the range of 100 to 200°C, or 100 to 180°C, or 100 to 150°C, or 120 to 200°C, or 120 to 180°C, or 120 to 150°C are preferred. Indeed, the temperature range of 120 to 150°C, or more preferably 120 to 140°C is particularly useful, being not so hot that energy is wasted, but nevertheless ensuring that the temperature of gas within outlet pipe 36 does not fall so low, or risk falling so low, that it rains in the gas outlet pipe. This would clearly be undesirable.

A temperature gauge T4 is provided at the exit of the condenser to measure the temperature of the liquid and gas and any remaining vapours as these exit the condenser. An outlet pipe 47 transfers the condensed liquid and remaining gas (which may comprise air and any small quantity of uncondensed vapour) in the direction of arrow 48 towards a separator 80, here a separator tank 80. A sight glass 32 may be provided to examine visually the gas and condensed liquid being delivered to separator 80. A vacuum pump 70 draws gas from condenser 60 (or alternatively from another part of the apparatus), optionally through a sight glass 32 along path 38, to maintain a vacuum within apparatus 10.

In separator 80, liquids are drained via a valve 24 and gas, typically all or mostly air, is blown by fan 90 back into treatment chamber 40. The gas circulated is typically air plus whatever gaseous vapours that remain. Advantageously, the apparatus is operated such that all, or virtually all, or most, of the vapours evaporated from the starter material are condensed within the condenser 60 and so separated out in separator 80.

Once the apparatus is fully operational, typically, over the time the material remains within the treatment chamber, all volatile substances originally within starter material are evaporated and extracted from the treatment chamber into condenser 60, before being condensed, and separated out via separator 80, leaving now significantly drier solids to exit.

Starter material holding tank 20 is preferably provided with a mixer to mix the starter material into a more consistent form.

Starter material holding tank 20 is preferably a heated tank so that starter material may be pre-heated. This heat may be provided in several ways, for example, by a thermal liquid heater jacket or some other form of heater. A particularly useful and energy-efficient embodiment is to take the hot water from the condenser and circulate this into a heat exchanger with the starter material in the holding tank 20. This may be an internal heat exchanger such as a spiral pipe within holding tank 20 or, more preferably, a thermal liquid jacket into which hot water is circulated by a pump (not shown). Thus, a hot water outlet pipe 62 from condenser 60 may be provided to circulate hot water (as shown by arrows 68) to a heat exchanger (not shown) in holding tank 20.

Thus, in this preferred embodiment, heat from the condenser is used up pre-heating the starter material, and thereby avoiding the resultant hot water from the condenser which would otherwise have to be disposed of as a waste product. At temperatures of room temperature or less, the still heated but now cooler cooling water from the condenser can typically be disposed of locally.

A prototype apparatus has been used with multiple test starter materials to assess performance. The results are shown in Figures 3A to 3E. In Figure 3A, distillery by-products pot ale and draff mix, and spent wash were treated. As can be seen from the table, the moisture content of starter material; varied between approximately 75% and 80% and the dry solid content varied between approximately 25% and 20%. The temperature of oil used was 180°C on input to the treatment chamber and 165°C on exit. The entry temperature of the product at T1 was between 20 and 30°C. The temperature of the product on exit at second end 46 (at T5) was between 110 and 118°C.

The temperature T3 of extracted gas (typically air and vapour) on entry to the condenser was measured and, when a stable steady state was reached, was kept at 135°C. A significant temperature drop across the condenser to 50°C at T4 was observed. The length of time the product spent within the chamber may be approximated by the quantity of product (in other words material) processed per hour, which for pot ale and draff mix was 40 litres per hour and for the spent wash was 60 litres per hour.

The results for pot ale and draff mix were very good with 84% dry solids with a moisture content of 16% being provided on exit, the remaining liquid having been extracted. The spent wash results were even better, with a dry solid content of over 93% and a moisture content of less than 7%.

Turning to dairy products, in Figure 3B, the thermal oil was again provided at about 180°C and exited at about 165°C. Air entering the condenser at T3 was well above 100°C, somewhere between 130 and 135°C and the temperature of the air exiting the condenser was 50°C or below, either 50 or 40°C.

As might be expected, the temperature of the product entering was pretty cold, just below 0°C to just above 0°C (-1°C for the milk cake by-product and 3°C for the whey by-product).

The temperature of the product at T5 on exit was between 100 and 115°C. The milk cake had an initial moisture content of just over 73% and post-treatment a moisture content of under 9%. The whey by-product had an initial moisture content of over 98% and yet, on exit, a very similar moisture content to the milk cake of just over 7%. This is a remarkable result for two very different initial materials, one with less than three quarters moisture and one with almost 100% moisture on entry.

In Figure 3C, sewage sludge results can be seen. The temperature of the product on entry at T1 was 8°C and on exit was 90°C. Interestingly, this temperature on exit was sufficient to provide a change in moisture content from over 96% on entry to just over 6% on exit at second end 46. The temperature of extracted gas entering the condenser at T3 was 135°C, and leaving at T4 was 40°C.

Figure 3D shows and example of damp flowable solids, in this case spent coffee grounds, in which the moisture content pre-treatment was 73%. Interestingly, this took a little less time (as evidence by the slightly increased amount of 55 litres per hour compared to, for example sewage sludge or the dairy products) to achieve a post-treatment moisture content of 10%. The air entering the condenser at T3 at 126°C is one of the lowest and indicates that the process can be carried out at a lower temperature (lower than 140°C) whilst still retaining good post-treatment moisture levels with a reduced energy requirement.

Operational costs of running the apparatus are not insignificant and, therefore, the insight gained by providing temperature gauges, for example T3 on entry to the condenser and, optionally, T2 on exit to the chamber, can be advantageous in adequately controlling the system and improving energy efficiency of the process, in other words, achieving the desired result of dry product, without wasting energy on unnecessary heating beyond that sufficient to prevent rain in the gas outlet pipe 36.

Turning to Figure 3E, in contrast to the fish by-product with approximately 40% moisture, hatchery by-product was almost 100% water on entry. Nevertheless, a greater volume per hour (60 Ithr) illustrates that a satisfactory result can be achieved even on this very watery initial starter material in a sensible time frame, volumetrically reducing the moisture content from over 99% to 10% with a consequent reduction in volume. The egg spinnings were somewhere in between, with a moisture content of over 71% pre-treatment and a moisture content of 3% on exit. A seemingly very energy efficient process can be maintained in that the gas and vapour entering the condenser were at a very respectably low 128°C.

Volumetrically reducing the waste into a much smaller dry solid component is very useful to facilitate onward transport and processing in an efficient and cost-effective manner.

However, it is advantageous if the removed moisture content in the form of the condensed liquid can be suitably disposed of. This will depend upon its content. A couple of examples are given in the Figures.

Figure 4A shows the analytical results for the condensed liquid from the pot ale and draff mix. Pre-treatment the pot ale and draff mix starter material had a chemical oxygen demand of 68,900 milligrams per litre, a pH of 3.87, and a suspended solids content that was unknown. Post-treatment the condensed liquid which, in this case for this particular starter material, is recovered water had a chemical oxygen demand (COD) of 5,450, a pH of 3.87 and suspended solids of 13 milligrams per litre.

Figure 4B shows the results for spent wash. Pre-treatment the spent wash starter material had a COD of 66,535 milligrams per litre, a pH of 4.02, and a suspended solid content of 13,470 milligrams per litre. Post-treatment the recovered liquid, which again in this case, was recovered water, had a COD of 3,577 milligrams per litre, a pH of 3.22 and a suspended solid content of 3 milligrams per litre. A second test is also shown with spent wash starter material having a COD of 94,750 milligrams per litre, a pH of 4.16, and a suspended solids of 40,670 milligrams per litre. These values were reduced in the recovered liquid post-treatment to give a COD of 1,639 milligrams per litre, a pH of 3.44, and a suspended solids content of 3 milligrams per litre. Following further filtering, the recovered filtered liquid had a COD of 926 milligrams per litre, a pH of 3.52, and a suspended solids content of 3 milligrams per litre.

Referring to Figure 5, the dairy product whey starer material prior to treatment had a pH of 3.42, a COD of 117,200 milligrams per litre and a biological oxygen demand (BOD) of 43,710 milligrams per litre. Post-treatment the pH had reduced to 2.77, the chemical oxygen demand was measured to be 4,750 milligrams per litre, and the biological oxygen demand had reduced to 146 milligrams per litre. Following filtering the chemical oxygen demand reduced slightly further to 4,660 milligrams per litre and the biological oxygen demand reduced significantly to just over 16 milligrams per litre.

As an example, photographs in Figure 6A show the initially very wet, almost 100% moisture, whey starter material, in Figure 6B the recovered liquid condensate which is a clear, odourless, colourless liquid, and in Figure 6C the recovered dry, brown solids.

The present inventor has appreciated that continuous screw conveyors with rotating continuous screws such as that described in W02017/153733 IMRIE work best with particular materials e.g. of particular consistency. This can restrict the starter materials these can be used with, and where they can be used. Furthermore, variation in tilt angles of screw conveyers can lead to a drop in efficiency, as the screw is less efficient, so where a particular tilt angle is needed for a particular material, and/or location, a drop in efficiency may result. This is undesirable.

Indeed, continuous screw conveyers with rotating continuous screws such as that described in W02017/153733 IMRIE are challenging to use with certain types of material for example, initially very viscous materials, or indeed with fragile or friable materials, limiting their usability and breadth of application. For example, if the material is very thick or sticky then handling with a continuous screw conveyor may result in a jam of the rotating continuous screws.

Furthermore, if the material is particularly abrasive this can lead to wear and tear of the continuous rotating screws, reducing their effectiveness and lifetime.

A more flexible solution that can be used for different waste products from different industries, preferably at a variety of sites, and also provides a highly efficient and (relatively) low energy process is desirable. The inventor has developed such a flexible solution, that also improves upon the energy efficiency of W02017/153733 IMRIE.

In one or more embodiments this involves the use of a rotating paddle conveyer with a number of discrete paddles, preferably a heated rotating paddle conveyer with heated paddles. Typically, this may be a hollow rotating heated paddle conveyer.

Discrete paddles (with one or more gaps 47, 57, laterally and/or longitudinally between them) as opposed to continuous screw threads facilitates a certain amount of back flow of material within the dryer, extending the applicability of the apparatus as a whole to a wider variety of materials, with a wider range of moisture and solids content.

As the material moves through the dryer, the discrete paddles ensure that the it is well mixed and that it flows easily through the machine. The paddles give excellent mixing in radial direction. The product is typically not mixed to the same extent in axial direction by the paddles if at all. It moves though the dryer, with more or less the same retention time for all parts of the material, so providing a final end product that better meets a desirable end product specification. An even flow through the dryer gives provides for more or less the same retention time, giving a more consistent end-product.

In a preferred embodiment, the paddles are configured to provide a small impetus to the material to be conveyed along, from a first end 44 to a second end 46 of the dryer 40. This configuration may be specially shaped paddles, as one example, a paddle of increasing thickness towards its base on the side towards the second end 46, so as the paddle is driven into the material when it rotates, it not only breaks material apart, it imparts lateral motion to some of the material towards the second end. The shape of the external surfaces of the paddles (e.g. facing the second end) may also form a discontinuous screw thread but as described above this is not necessary to achieve the effect of lateral motion from the first to the second end.

Preferably, as shown in Figures 1B and 2B, the paddles 54, 56 and/or paddle portions 54A, 54B, 56A, 56B extend 180 degrees around its longitudinal axis of rotation of the rotating paddle dryer, more preferably s 180 degrees, or s 270 degrees, or s 360 degrees around its longitudinal axis. Preferably gaps 57 are formed from one paddle portion to the next. Preferably the paddles are hollow, preferably in fluid communication with a hollow central conduit 55.

The invention provides a unique apparatus capable of operating successfully with many different materials (typically waste products or by-products) from many different industries. In one or more embodiments, this is assisted by providing a controllable holding tank 20 for receiving the starter material (also known as raw product).

Indeed, in one more preferred embodiments, depending on the type of material, the apparatus may also comprise a disc stack separator to remove some of the water before even initial processing in the holding tank 20. The optional disc stack separator removes water leaving a thicker sludge as a starter material. In other words, the dick stack separator can provide a starter material of more consistent consistency.

The starter material (waste product), either directly or pre-processed via a disc separator, is put into a holding tank 20 preferably to be mixed, and preferably also pre-heated, to keep the product in a more consistent state for later processing in the treatment chamber. The material in the holding tank is mixed preferably continuously (although optionally intermittently).

Once the apparatus 10 is running, the mixing tank 20 may be preheated by the heated water coming out of the cooling side of the condenser 60. This improves the efficiency of the later processing and the efficiency of the apparatus overall.

The starter material in the holding tank 20 is pumped or augured up to a small hopper above the rotary valve 26 on the input (first) end of the treatment chamber. The rotary valve feeds the product in at a consistent flow and also hold the vacuum in the treatment chamber.

The starter material is fed into the specially designed paddle drier 50 within the treatment chamber 40. The hollow paddles 54, 56 and hollow central conduits or shaft(s) 55 are heated by thermal oil. The paddles are specially designed for mixing and self-cleaning as these dry and mix, and optionally convey, the product through the treatment chamber. In preferred embodiments, two hollow shafts with hollow paddles, e.g. generally figure of eight paddles, turn in opposite directions in the chamber. The internal walls of the treatment may have an w-(omega) shape that follows the contours of the paddles The specially shaped paddles do not necessarily have a transport function but are designed for maximum heat transfer. This results in an excellent control of the temperature of the product and enables a uniform product quality. The paddle dryer is compact having many square meters of heat exchanging surface relative to the volume.

Preferably, the outer casing is also heated by thermal oil. Typically, this is done with carefully designed baffles to control the oil flow. The selected temperature of the thermal oil is typically the same throughout but will vary depending on the material being processed.

Working under vacuum throughout the apparatus reduces the required temperature by around 30% and also controls emissions from the process. Indeed, emissions are substantially prevented. A small circulation fan fitted to the inlet of the chamber gently keeps the air circulating through the apparatus while the apparatus is under vacuum.

Gas and vapour will come off the paddle drier system in the treatment chamber and be drawn by the slight vacuum typically provided at the far end of the condenser and gentle flow up the vapour discharge pipe to the condenser. There will be cooling water circulating through the condenser to cool down the vapour and back to liquid/water which will be dropped into a separator vessel below the condenser. There will be a U bend at the bottom of the vessel to allow the cool water to discharge and keep the vacuum in the system.

There will be temperature control probes fitted at the material intake into the treatment chamber (T1), lower end of the vapour discharge pipe 36 (T2), the top of the condenser 60 (T3), and the discharge of the condenser 60 (T4); these are controlled via readings seen at and control signals delivered from e.g. a main control panel.

At the outlet side, the product moves out of the chamber via an adjustable overflow. Dry solids are discharged through a rotary valve 26 at the solids discharge end of the paddle drier. The rotary valve discharges the solids into a small discharge auger (not shown) which feeds into the dry product storage bins.

The thermal oil is heated by an onsite boiler. Optionally this may be heated by scavenging spare heat from the system and/or heating using a bio mass boiler optionally burning the recovered dry solids as a fuel.

The apparatus of the invention may be fitted inside a container unit of standard size, for easy of transport by road or rail from one site to another. This means that each site does not need to build its own waste treatment unit as one may be temporarily installed before being relocated. Containerising the apparatus so it can be moved to different sites is very useful.

Nevertheless, it is the provision of the various elements of the invention as laid out in this text, particularly in the claims and/or statements of invention, that provide for more flexible yet controlled processing using a particular type of dryer a rotating paddle dryer within the treatment chamber, which means that the apparatus can be used to treat a wider range of raw product from a wider range of industries and can provide a more uniform end product without having to design a bespoke apparatus and process for each one. In one more embodiments, a more consistent starter material can be produced. More uniform product can be achieved even with very different starter materials e.g. with vastly different moisture content, and yet processing times are very generally the same, the apparatus capable of adapting to very water material which can be input at a faster rate than a dryer starter material. Where a heat transfer area of say 30 m2 is provided by discrete paddles, processing of 2000-3000 litre per hour in a wide range of different materials can be achieved. All this in an apparatus of relatively small footprint, that can be built within a standard container, or other portable, mobile apparatus.

Apparatus holding chamber (e.g. tank) 22 mixer 24 valve delivery pipe 26 rotary valve 28 material path material delivery mechanism (e.g. pump or auger) 32 sight glass 36 outlet pipe 38 gas and/or vapour path treatment chamber 42 jacket thermal oil circuit 44 first end 46 second end 48 condensed liquid path 47 gap heated material dryer (e.g. hollow rotating paddle dryer, optionally also a conveyor) 52 paddle dryer thermal oil circuit 54 paddles, series of paddles 54A, 54B twin rows of paddles on first shaft/ hollow conduit hollow conduit or shaft 56 paddles, second series of paddles 56A, 56B twin rows of paddles on second shaft/ hollow conduit 57 gap 58 free space above paddle dryer condenser 62 hot water outlet pipe 66 cooling water inlet pipe 68 direction of heated water from condenser vacuum pump separator 90 fan e.g. blower T1 temperature gauge measuring temperature of product entering treatment chamber T2 temperature gauge measuring temperature of extracted gas and vapour leaving treatment chamber T3 temperature gauge measuring temperature of extracted gas and vapour entering condenser T4 temperature gauge measuring temperature of extracted gas and vapour leaving condenser temperature gauge measuring temperature of product leaving treatment chamber

Claims (27)

1. Claims 1. An apparatus for treating material, the apparatus comprising: a holding chamber for starter material; a material delivery mechanism for delivering starter material from the holding chamber to a treatment chamber; the treatment chamber having a first end configured to receive starter material to be treated and a second end configured to allow egress of solids, and being configured to hold a vacuum, and further comprising a gas inlet port and a gas outlet port for flowing gas through the treatment chamber; - at least one heated material dryer configured to heat and mix material as it travels through the treatment chamber in a direction from the first end towards the second end; - a condenser configured to receive extracted gas and vapour from the chamber and condense the vapour into liquid form; a separator configured to separate extracted gases and condensed liquids; - a vacuum pump configured to create a vacuum in the treatment chamber and in a gas circulation circuit from the treatment chamber via the condenser and separator back to the treatment chamber; a gas circulator configured to circulate extracted gas and vapour via the gas circulation circuit from the treatment chamber to the condenser and separator and back into the treatment chamber; and further comprising: a mixer configured to mix starter material in the holding chamber; -the at least one heated material dryer comprising one or more heated rotating paddle dryers each having a plurality of discrete paddles.
2. 2. Apparatus according to claim 1 further in which: the condenser comprises a cooling water circuit to draw in cold water, and to cool gases and vapours in the condenser, and to deliver heated water to a hot water outlet pipe; - the hot water outlet pipe is configured to deliver hot water to the holding chamber from the condenser to pre-heat starter material in the holding chamber.
3. 3. Apparatus according to any preceding claim in which the one or more rotating paddle dryers comprise one or more hollow thermally-heated rotating paddle dryers.
4. 4. Apparatus according to any preceding claim in which at least two intermeshing rotating paddle dryers are provided.
5. 5. Apparatus according to any preceding claim in which the one or more heated paddle dryers comprise one or more series of paddles each comprising a plurality of discrete paddles, adjacent paddles having gaps therebetween.
6. 6. Apparatus according to claim 5 in which the one or more series of paddles each comprise one or more rows of paddle portions having gaps therebetween.
7. 7. Apparatus according to claim 6 in which each of the one or more paddle dryers comprises two or more rows of paddles spaced apart along a central shaft, paddles of a first row of paddles alternating in a longitudinal direction with paddles in a second row, neighbouring paddles in each respective row extending in a generally, or substantially, transverse direction.
8. 8. Apparatus according to any claim any preceding claim in which a paddle, or paddle portion where provided, extends 180 degrees, or 270 degrees, or 360 degrees around their respective longitudinal axis.
9. 9. Apparatus according to any preceding claim in which number of paddles on a central shaft of each paddle dryer per meter length is between 2 and 12, or between 3 and 6.
10. 10. Apparatus according to any preceding claim in which the one or more heated paddle dryers is or are configured not to draw material along through the chamber in a direction from the first towards the second end.
11. 11. Apparatus according to any preceding claim in which the one or more heated paddle dryers is or are configured to draw material along through the chamber in a direction from the first towards the second end.
12. 12. Apparatus according to claim 11 in which the exposed surfaces of one side of the paddles of the one or more rotating paddle conveyors form a discontinuous screw thread.
13. 13. Apparatus according to any preceding claim in which the paddles, or paddle portions, where provided, have a wedge-shaped cross-section.
14. 14. Apparatus according to any preceding claim further comprising a temperature gauge (T3) for measuring the temperatures of extracted gas and vapour at a gas entrance to the condenser.
15. 15. Apparatus according to claim 14 comprising a control unit configured to maintain gas and vapours at the entrance to the condenser (T3) at a temperature of e 00°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C or 120°C to 140°C.
16. 16. Apparatus according to any preceding claim further comprising a temperature gauge (T2) for measuring the temperatures of extracted gas and vapour at a gas outlet from the treatment chamber.
17. 17. Apparatus according to claim 16 in which the control unit configured to maintain gas and vapours at the exit of the treatment chamber (T2) at a temperature of L.100°C, or 100°C to 200°C, or 100°C to 180°C or 100°C to 150°C, or 120°C to 200°C or 120°C to 180°C, 120°C to 150°C or 120°C to 140°C.
18. 18. Apparatus according to any preceding claim in which a temperature gauge (T4) is provided at (e.g. near or adjacent) the exit of the condenser for measuring the temperatures of cooled extracted gases and vapours
19. 19. Apparatus according to any preceding claim in which a temperature gauge (T1) is provided at (e.g. near or adjacent) the material entrance to the treatment chamber condenser for measuring the temperature of starter material (e.g. pre-heated starter material).
20. 20. An apparatus according to any preceding claim in which the gas inlet port and gas outlet port are configured so that vapours and gas flow in a direction generally, or substantially, in the same general direction of movement of slurry and/or solids drawn though the treatment chamber from the first end towards the second end.
21. 21. A method for treating material, using an apparatus according to any of claims 1 to 20, the method comprising: holding starter material in a holding chamber; - delivering starter material from the holding chamber to a treatment chamber; receiving starter material to be treated at a first end of the treatment chamber having and egressing solids at a second end, - flowing gas through the treatment chamber from a gas inlet port to a gas outlet port for; - using a vacuum pump to provide a vacuum in the treatment chamber, and in a gas circulation circuit from the treatment chamber via the condenser and separator back to the treatment chamber; - using a gas circulator to circulate extracted gas and vapour via the gas circulation circuit from the treatment chamber to the condenser and separator and back into the treatment chamber; - treating material using at least one heated material dryer configured to heat and mix material as it travels through the treatment chamber in a direction from the first end towards the second end; receiving extracted gas and vapour from the chamber into a condenser and condensing the vapours into liquid form; using a separator to separate extracted gas and vapour from condensed liquids; and further comprising: using a mixer to mix starter material in the holding chamber; using at least one heated material dryer comprising one or more heated rotating paddle dryers each having a plurality of discrete paddles, and using the rotating paddle dryer to treat the material.
22. 22. A method according to claim 21 further comprising: using the condenser to draw in cold water, and to cool gas and vapour in the condenser, and to deliver heated water to a hot water outlet pipe; delivering hot water via the hot water outlet pipe to the holding chamber from the condenser to pre-heat starter material in the holding chamber.
23. 23. A method according to according to claim 21 or 22 comprising: maintaining gas and vapours at the entrance to the condenser (T3) at a temperature of 100°C, or 100°C to 150°C, or 120°C to 140°C.
24. 24. A method according to any of claims 21 to 23 comprising: maintaining gas and vapour at the exit of the treatment chamber (T2) at a temperature of 100°C, or 100°C to 150°C, or 120°C to 140°C.
25. 25. A method according to any of claims 21 to 24 comprising: providing a vacuum in the treatment chamber in one of the following ranges: bar, bar, bar, bar, bar, 0.2 to 0.9 bar, 0.25 to 0.75 bar, 0.4 bar to 0.6 bar, 0.4 bar to 0.6 bar; or, providing a vacuum in the treatment chamber at one of the following values: 0.9 bar, 0.8 bar, 0.7 bar, 0.6 bar, 0.5 bar, 0.4 bar.
26. 26. A method according to any of claims 21 to 25 comprising maintaining the flow rate of gas through the chamber of: .1m/s, or.0.8m/s, or.s0.6m/s, or.s 0.5m/s, or 0.4m/s.
27. 27. A method according to any of claims 21 to 26 comprising: controlling the temperature of exiting solids to be 125°C, or.s120°C, or.s110°C, or.s100°C, or.s90°C.