 Wel i'r cyfnod, a gweithio'r Wolffesyn Cymru i'r cyfnod yr Bio-Soldat Cymru. Yn mynd i'r Mike Bradley. Rhywbeth yma'n cyfnod o'r Wolffesyn Cymru, a rhaid i'r profesiad yw'r Bio-Soldat Cymru i'r Unedig Pwgolig. Felly yn y Llyfrgell Gweithgol. A gydag yma yna'n ymlaen i gael y piler o'r labn, ac rhaid i'n gweithio'n gweithio'r cyfnod o'r ffordd o'r ffordd o'r ddweithiau, a how they might relate to your problems and needs in powder handling. So first of all we've got a test rig here. This simulates the flow of material particularly fine powders when we're doing the filling of road tankers and rail tankers. A lot of people have problems with getting just the right amount of material in the right condition in logistics tanks such as I described. I that rig we've got here, we place a significant quantity of powder in the top section, drop the material through, we can measure its condition of aeration, adjust that if necessary, catch the material in the bottom, see how it flows, how it settles, and what the bulk density is which is critical to filling those 10% we then re-circulate the material through a screw-convir here, so that bring some material back up to the top so that we can recirculate and do further tests. So I'm going to show you our pneumatic conveying test rigs. Pneumatic conveying is one of the areas that we're historically best known for. We have one of the world's best facilities for pneumatic conveying pilot plant testing and quite a number of Wolfson sent, ex-Wolfson send of people have become quite important in this area of industry ond. Felly we have here a blow tank test rig, which is very similar to what we use in industry. Much of our pilot plant equipment here is at the, shall we say, the smaller end of the industrial scale. So we can do testing which is realistic, which is scalable to what would happen in the plant. So this is very similar to what is used on a road tanker or a rail tanker or indeed a land-based blow tank, where powder is put into here, pressurised with air, and then the material is driven out around the pipelines. We have test pipelines which run around our building inside the building and also around the yard outside, something like 140 metres of pipeline of each of three different sizes, again commensurate with industrial sizing. The material then is received in the receiving hopper, which is on the top of the rig, so that we can measure the flow rate of material. We can adjust the air flow, adjust the powder flow, measure the way in which the powder behaves, and that gives us the properties we need to predict how it's going to behave in a full-scale pipeline. And then we've got a second rig over here, which works in many ways very similar. We have a blow tank which puts powder into the pipeline, supplied also with air from the same compressors. One of the differences on this rig is that in the midsection here we have what we call a full stream cross-cut sampler. And the advantage of that is that we can take samples of material between conveying runs and before and after conveying, so that we can actually measure change of the material during conveying, moisture uptake, particle degradation and so on. Rotary valves are a very important part of many pneumatic conveying systems, and to many users of pneumatic conveying systems they describe them as the bane of their lives, because there are so many different design options that need to be selected from, there are so many different potential problem areas with them, and there are so many different effects that they can have on the material. So a study of the science of how rotary valves work, how to select them, their interaction with the material is a very important part of our research and consultancy. One of the important things about most powders and bulk solids is that they are affected by ambient conditions. Temperature and humidity affect their moisture content, the way they flow, the way they behave, and very often ambient conditions vary in factories and in external storage piles and so on, but also many materials are processed at different conditions apart from ambient. So quite a lot of our work we use climate chambers in order to condition material and measure their properties at those different conditions. So in this chamber here we can dial in temperature and humidity from north to 100% humidity and minus 40 to plus 180 degrees C, and we have in here a machine which measures the flow properties of the materials and so we can condition the material, we can undertake the testing at those controlled conditions. One of the most important keys to success in bulk solids handling is understanding the behavior of the material. Measuring that material behavior is what we call characterization, and characterization instruments is something we've done a lot of development of here at the Wolfson Centre. One of the things that happens with powders when they move, they have a tendency to separate. This is a mixture of mung beans and couscous that have a size ratio of about 3 to 1. Many real bulk solids actually have a wider size range than that, and you can see that what has happened, as the material has been filled into here, the beans being larger have rolled towards the outside, the couscous being smaller has stayed in the middle. So if this is something that we've deliberately made a mixture of, or indeed if it's just a natural material with a range of sizes, this can cause us immense problems with processing. So what we've got here is a characterization instrument that enables us to measure that tendency of materials to separate. So this was developed through a project funded by UK Research Council, EPSRC, a number of years ago, and it's a segregation tester. This is what we call autosegregation of materials, and it's the same process that happens when you see sand and stones on the beach. You get the pebbles at the top, the shingle partway down the sand at the bottom, and this is the natural tendency of materials. So we put our test material into this little mixer here, we mix it, we allow it to flow out, form an angle of repose here, and then we can sample it, and that gives us a measurement of this natural tendency to segregate. And that tells us either if that's going to be a problem in a process, we need to either change the material, or we need to change the process in order to reduce the tendency to segregate the material. Another important thing in many bulk solids processes is the breakage of particles. When you buy a jar of coffee granules, you expect to get a jar of granules, not half a jar of granules and half a jar of dust. So the breakage of materials when they're handled, and reduced perhaps from pellets into dust like this, causes a lot of problems in many industrial processes. So what we've developed here is another characterization technique which enables us to measure that particle breakage. It's what we call a degradation tester. So we feed the particles into this spinning disk here from which they flow through the disk, they're fired against these targets here, and then we pick up the broken bits afterwards, the broken pellets or whatever else they may be, granules, and we do a measurement of the degradation. From that we determine what we call the breakage matrix, which is a physical numerical representation of the tendency of the material to break. And then from that breakage matrix we can predict how these particles are going to break down in handling, whether it be through a pneumatic conveyor, a transfer point in a belt conveyor, drop onto a stockpile or any other part of a process. And then we can use this to evaluate the improvements to maybe the strength of the particles or the harshness of the process can be reduced, which again we can evaluate using this tester. So let's talk a little bit about dust. Dust causes immense problems in every industry that handles and processes bulk and powder materials, whether we're talking minerals and mining, quarrying or at the other end pharmaceuticals, food, anywhere there are particulate materials there will be dust. Dust causes problems with health. If you breathe dust in it can be very harmful to health, a recognition in recent years of the dangers of breathing particulate materials, especially what are known as PM5s and PM2.5s has revolutionised the attention this area gets. Not only from the perspective of inhaling of dust, but also dust explosions. Dust explosions kill many people as well. And the expense of tidying up the mess created by dust and the annoyance that it causes to neighbours is also a huge problem in many industries. So three different things here I'm going to talk about that relate to dust. I'm going to start over here first of all. This machine answers the question how dusty is the material that I'm going to be handling? So this is what we call a dust emissivity test. It's a characterisation technique where we place some dust inside this rotator, place our bulk material inside this rotating drum and as it turns so the material tumbles around inside we draw air through and we collect the dust on a filter in here. And the quantity of dust collected gives us an objective measurement of the ability of that material to emit dust. So that's very important to us if we're handling let's say a new cargo that we've not come across before or if we're manufacturing a material that is going to be used in a factory a particulate material. They need to know how dusty is it going to be. So that's how dusty a material is. Obviously very often we use filters in order to capture dust so we have a filter test rig here. This enables us to run tests and undertake research on the performance of filters, how good they are at capturing and separating materials and not allowing dust through and indeed how easy they are to clean. So the design of the filters, the type of material used, the design of the baghouse itself, these are all critical things that we undertake a lot of research and testing on. And then over here still related to filters, this is our filter media test rig. So in here we can put samples of different types of the filtration medium that go into these filters and we can make an objective test at how good they are at stopping the powder, the dust from getting through and indeed what pressure drop that they cause. And so this gives us the fundamental information that enables us to evaluate the materials that goes to manufacture these filters that we see here. So you've seen the pilot plant area where we have the more industrial scale of test equipment. Now I'm just going to show you briefly around our laboratory area where we do small scale bulk experiments and characterization of materials. So first of all I'm going to take you over to these instruments over here. This instrument here is what we call the DVS or Dynamic Vapor Sorption Analyzer. I mentioned earlier that most powders and bulk solids are affected to some degree by the effect of humidity, moisture uptake and loss. And what this instrument does, it measures how the moisture content varies with ambient humidity that the powder is exposed to. So as you can see on the graph here, along the bottom we have the humidity of the air and on the y axis you can see this is how the mass of the powder changes because of uptake and then loss of water. So here we see placing a sample of powder in the DVS in order to undertake a measurement of its response to airborne humidity. So once the chamber is closed up the computer control on this instrument automatically ramps humidity up and down with stocks for a suitable period at step values of humidity and it observes for the stability of the material mass of that humidity and how that changes before it moves on to the next one. Then from that we can construct what we call the moisture sorption curve of the powder which shows how the moisture content varies with humidity. So here we have an instrument that measures the density of particles. We have two different types of densities with bulk materials. We have what we call the bulk density which is the volume that an assembly of particles occupies in relation to its mass but of course part of that is full of air. So we also need to know the true solid density of the particles and that's what this equipment measures. It's called a picnometer. So let's talk about powder flow properties. This instrument the PFT or Powder Flow Ability Tester developed here at the Wolfson Centre and used now worldwide manufactured by Brookfield Engineering. This measures the ability of a powder to flow or not flow in a process and one of the things about powders is when you have a powder that is fine or that has a high surface energy or that is moist it demonstrates what we call cohesion which is the ability to stick together. Let me just demonstrate this. We're all familiar with making a snowball. This isn't snow or may look like it it's the same sort of colour. This is actually a pharmaceutical powder and you can see it's in a loose condition here. If I pick this up in my hand like many powders and I squeeze it when I open my hand it maintains a structure a strength here and this makes the powder hard to handle. So what we measure in terms of powder flow properties is the relationship between how hard I've squeezed the powder and the strength of the resulting aglomerate and the relationship between those two is what we call the flow function. So the way in which this instrument works is we place a powder sample in the test cell here with this placed we start a test under computer control which compacts the powder shears it in order to consolidate it at a controlled stress and then we change to a different stress and we shear again to measure the strength of the powder. Under automatic control this runs about 40 different tests at different values of consolidation stress and test stress. The data comes up on a graph over here which shows the effect of the stress the measured strength of the material versus the test stress that we use for a range of different consolidating stresses and on here what we see is what are known as the yield loci for the powder for different consolidation stresses. They're fitted with Moore's circles as shown and then from that analysis we calculate what is known as the flow function of the powder and the flow function is the unique fingerprint of the powder that relates its strength to the stress that has been applied to it. So by using this instrument and making that measurement of powder flow function we can then determine how large an outlet is required on a hopper or a feeder or a silo to get reliable flow with this material or alternatively we can use this the other way we use this very frequently and many of the users worldwide use it in this way for powder formulation optimization in other words adjusting the formulation of their powders and the manufacturing of their powders to generate as it were user friendly handling properties and that's one of the most popular uses of this but it's also widely used for quality control as well checking from batch to batch with powders that powders have consistent flow properties and those consistent flow properties often mean then that the the powder has consistent processing properties in its use so it's used for for example measurement of the coffee grounds that go into the pods that go into into coffee makers because a consistent flow ability here indicates a consistent particle property which means that then when you make the coffee using the pod you get a consistent flavour from the coffee also used for many other industries as well in pharmaceuticals in in aggregates inquiring mining and so on as well so here we have the so-called powder spreadability tester and this relates to additive manufacturing or 3d printing manufacturing of components by taking powders and fixing the grains together to make a component rather than taking a block of metal and machining away what you don't want is very is a very fast growing trend in manufacturing lends itself very well to high value components and small production runs and so on so that's the powder spreadability tester moving on we talked yesterday about segregation and the ability of particles the natural tendency of particles to separate by size we referred to what we call free surface segregation where when you have a heap of particles the larger ones tend to roll to the bottom the smaller ones than to stay in the middle there is a different kind of segregation which occurs commonly in many processes called air induced segregation and this commonly happens where a powder blend may be for a pharmaceutical or food manufacturing typically is dropped down a shoot from one process to another and the counter flow of air causes the fines to be stripped out and this instrument captures and makes an objective measurement of that trend of the powder to separate by size so within this we place the powder in a hopper on the top here and it runs an automatic program that turns on an airflow drops the powder and then we separate the parts of this column and we measure the size distribution or chemical analysis or maybe taste or smell or whatever it else that is we're interested in between those separate segments so the machine works automatically it runs a test in a standard way and then that provides information to us really about how easily that powder separates and again we can use that either for improvement of processes or for improvement of formulations to reduce that problem in manufacturing size and shape analysis of the particles within a powder or bulk solid is very important because that controls critically many of the aspects of their behavior we have four different methods of measuring particle sizes and shapes here at the Wolfson centre all of which have their own advantages and disadvantages so the machine we have over here this is the optical size and shape analyzer this uses air to disperse particles onto a slide it then takes pictures of all the individual particles and produces for us an analysis of the distribution of the sizes and also the distribution of the shapes as well and then over here on this side we have a laser particle size analyzer so this uses diffraction of laser light the particles go into this dispenser here and in the machine the particles are projected in an air stream across a laser sheet and the diffraction of that laser light enables us then to determine the size distribution of the particles within that sample this is particularly useful for where we're dealing with extremely fine particles often for coarser particles we use sieve analysis and we have a sieve analyzer so the sieve analyzer is operated from the computer here and then this then gives us a simple print out of the size distribution of the particles within the analysis as we see here the principle of sieve analysis for size distribution measurement is to use a stack of sieves something like this with different size holes so we place them on top of one another we shake the sieves and the particles of different sizes stop on those different sieves now the old-fashioned way of doing this of course is to weigh these sieves put them together put the material in shake it and then take the part and weigh them again that's very labor intensive and very often we have dozens and dozens of sieve analyses to do for a project so we use a computer controlled robotic sieve analyzer here and the way in which this works is that we place the sieves inside the machine and we have a variety of sieves of different sizes in here largest at the top the smallest at the bottom and when we're ready to run what we do is to load the sample sample is pre-wade over here we place that in the machine and then we start the machine under computer control at the end of the cleaning cycle the machine brings all the clean sieves back together ready for the next analysis so here we have another method for size analysis by sieving that applies particularly to particles that are too fine or too cohesive to drop through a normal vibrating sieve under gravity and this we call our air swept sieve the way in this machine the way in which this machine works is that we have a variety of different sizes of sieves here but we can go down to much smaller sizes than on the ordinary shaker sieve this enables us to sieve down to about 12 microns and the way in which the machine works so as well as having the vibration on the sieve that goes in here it also has in here a device which projects an airflow through the sieve while the vibration is being applied and that enables us to encourage a flow through the sieve of particles that would otherwise either ball up or stick on the sieve and there are many advantages of sieve analysis one being that it's a particularly direct and reliable way of sizing particles but obviously this extends the reach of that technology so some other different characterization techniques as well which we use here quite widely this is the poured and tapped bulk density tester so we put a sample of powder in here and after tapping it we see how the bulk density varies and this is a common test used in many different industries to determine the bulk density for the equipment design but also to look at how bulk density changes with tapping which gives us a measure of the powder behaviour so we take the measuring cylinder and we would weigh out a certain quantity of material and having weighed this material we would put it in the cylinder here read off the volume as poured place it on the machine and we would allow that to run for a designated number of taps it's interesting to note that different industries have different standards for the number of taps used and then we can see the change in the volume that occurs here and hence we can obtain both the initial poured density the settled tap density and the ratio between the two which is often known as the housing ratio then we have the so-called texture analyzer here this is essentially a computer controlled press which enables us to apply a vertical force a vertical movement and measure the force so we can use this for compacting materials again to see how for example the bulk density varies with stress but also for larger particles we can put a fixture in here where we can actually break the particles and measure the individual particle strength which is important in many instances moving on this is the particle attrition tester in a small scale so this we use to measure the tendency of particles to break during impact again so inside here we have a rotating disc particles are fed in through the through the funnel into this rotating disc here they come down the channels accelerate out and then they hit the targets in here we then pick up the broken particles and we can do a size analysis and therefore just see how much the particles break down so this again is a good method for measuring the breakage matrix of particles which we can use that information then to predict the level of breakage within a certain process or again we can use it to aid formulation by changing the structure of the particles in order to make them stronger more resistant to break down mixing is an important process for many particulate materials lots of particulate products are made of particles of different species that are blended together and this is one of a number of different types of mixing technology that we use that we test here at the Wilson Centre this is known as the turbulent mixer so the sample for mixing goes into the pot here and then that's put on the machine in order to blend it and as I say this is just one of many different mixing technologies that we experiment with here at the Wilson Centre because different types of materials require a different action in order to mix them effectively a very important aspect of bulk solids analysis is sample subdivision when we receive a large sample of material maybe from a customer's plant or perhaps from our own pilot plant this is much too large a sample to analyse whether we want to do sieve analysis flow property testing or anything like that now if we just put a scoop in and take some material out that is not going to be representative of the average of what's in the larger sample because in this larger sample we will have segregation the particles will naturally be separated by size so we need to find a way of subdividing this to obtain subsamples that are fully representative we use this machine here which is known as a spinning riffler so we have a hopper here a little feeder at the bottom and a number of bins here on the turntable material goes in the top and when we run this the material is fed out of the bottom of the hopper flowing down here in a first in first out discharge pattern or mass flow as we call it as the bins go round because they rotate continuously each of these bins receives multiple cuts through that large sample so each of these eight smaller subsamples is fully representative of the average of what we put in and therefore when we analyse this the results are meaningful in relation to the larger sample that we started with here we have a fluidised bed test rig fluidised bed processes are used in a very wide range of industrial applications where we need reaction between gases and solids catalytic cracking of crude oil to produce petroleum products is one of the best now but there are many many others as well so what we have here we have effectively a a cylinder glass tube in this particular case and in here we have our powder then from the bottom we introduce the gas as the gas flows up through here it causes movement and dilation of the powder and the intimate contact between the powder and the gas then gives us a very good reaction so whether we're looking at heating cooling chemical reaction or anywhere else where we want close contact between gas and powder for process purposes this technology is widely used and we can set this up to simulate the movement of the fluid bed and the process that is going on inside so you've had the short tour of our facilities here at the Wolfson Centre you've seen our extensive pilot plant facilities and our labs as well for characterisation and so on all of this equipment is available for use for industrial purposes for design projects for troubleshooting and so on if you come on one of our short courses you can come and see this in person or indeed on some of the courses you'll get your hands on and actually get to use some of this equipment and of course if you have requirements to deal with bulk solids where there is currently limited knowledge then we get involved in research through lots of different means as well so thank you for your time and bearing with me and I hope we get to meet sometime