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Departamento Técnico de BP Bitumen

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Presentación del tema: "Departamento Técnico de BP Bitumen"— Transcripción de la presentación:

1 Departamento Técnico de BP Bitumen
PRODUCCIÓN DE BETÚN Departamento Técnico de BP Bitumen 1.0 TÍTULO – PRODUCCIÓN DE BETÚN A modo de introducción a esta presentación, cabe señalar que bp posee 14 centros de producción de betún en once países situados en América, Europa, Africa y Oceanía. En estos puntos, bp produce en la actualidad alrededor de 4 millones de toneladas anuales.

2 Introducción Definición de betún y clasificación de ligantes bituminosos Productos procedentes del crudo Composición química del betún Procesos de refino para la producción de betún Selección de crudos adecuados para betunes Otros productos bituminosos Calidad del betún 2.0 ALCANCE DE LA PRESENTACIÓN En esta texto acerca de la fabricación de betunes se cubren los puntos siguientes: Definición de betún y clasificación de los ligantes bituminosos Origen del betún y otros productos procedentes del crudo.NOTE FOR WEB DEVELOPERS: I realise this is a text for a talk, not for the extrante. If it needs to be translated, contact me on my . Otherwise, I just will translate the slides Chemical composition of bitumen - this will be very brief, I realise that very few people here if any are chemists. Refinery processes for bitumen production Selection of crude oils for bitumen Other bituminous products Bitumen quality

3 DEFINICIÓN DEL BETÚN Producto sólido, o líquido viscoso, formado esencialmente por hidrocarburos y sus derivados, soluble en tricloroetileno, poco volátil y que se ablanda gradualmente al calentarse. Presenta color negro o parduzco y tiene propiedades de impermeabilidad y adhesividad. Se obtiene como producto en el refino del petróleo, aunque puede presentarse también formando depósitos naturales. 3.0 BS 3690 DEFINITION OF BITUMEN The internationally agreed definition of bitumen that appears in BS 3690 is as follows. In fact this slide is slightly out of date because for health reasons the solvent now used is not carbon disulphide but trichloroethylene. This definition covers a number of materials but my talk is going to be concentrating on the production of petroleum bitumens.

4 Clasificación de los ligantes bituminosos
Betún Alquitrán Asfalto natural Ligantes del petróleo Alquitranes de carbón Alquitranes de madera 4.0 CLASSIFICATION OF BITUMINOUS BINDERS The next slide shows how petroleum bitumens fall into the general classification of bituminous binders. The BS 3690 definition of bitumen covers all the materials to the left of this slide but I am only going to speak about petroleum bitumens not the products which come under the heading of NATURAL ASPHALTS. I'm certainly not going to deal with tar and its uses. The origin of petroleum bitumens is crude oil which is a very variable and complicated mixture of chemical compounds formed from dead marine organisms decomposing over millions of years at enormous temperatures and pressures underground. In an oil refinery this complicated mixture of compounds is separated into a relatively small number of fractions which I'm sure will be familiar to you. Gilsonita Asfalto Asfalto Alquitrán de carretera lacustre mineral

5 Productos del crudo Número de Productos ligeros Carbonos 3 - 4 5 - 10
GLP Gasolinas Querosenos Gasóleos Lubricantes Fuél óleo pesado Betún 3 - 4 5 - 10 Crudo 24 - ~300 5.0 PRODUCTS FROM CRUDE OIL - LIGHT --> HEAVY PRODUCTS AND CARBON NUMBERS. LPG or bottle gas, gasoline or petrol, kerosene or paraffin, gas oil or heavy diesel, lubricating oil, heavy fuel oil and bitumen. To understand what makes these fractions light and these fractions heavy and also to understand how they are separated from the crude oil mixture it is necessary to know something of their chemical composition. Although there are millions of chemical compounds in crude oil, they have in common the fact that they are HYDROCARBONS. HYDROCARBONS is a term that chemists use to describe compounds which consist of carbon atoms and hydrogen atoms. In a hydrocarbon compound the carbon atoms are joined together to form a carbon skeleton and the hydrogen atoms are attached to the carbon atoms like flesh on the bones of the carbon skeleton. Obviously the more the number of carbon atoms joined together, so the bigger the hydrocarbon compound. To the right of this slide I have listed the carbon number ranges of the compounds in these familiar product fractions. LPG consists of compounds which contain 3-4 carbon atoms while gasoline contains compounds of about 5-10 carbon atoms. At the other end of the scale we have bitumen which typically has between 24 and 300 carbon atoms in the compounds it contains. So you can see from this that the compounds in bitumen are much bigger and heavier than the lighter products and there is also a much wider range of compounds. ~40 - ~300 Productos pesados

6 Propiedades de los productos
Número de Carbonos Punto de ebullición (°C) GLP Gasolina Queroseno Gasóleos Lubricantes Fuel óleo pesado Betún 3 - 4 5 - 10 24 - ~300 370 - 6.0 PRODUCTS FROM CRUDE OIL - CARBON NUMBERS AND BOILING POINTS. Because of the differences in carbon numbers and the differences in compound size that it produces, these products have different boiling points. LPG with only 3-4 carbon atom compounds boils between -10 and 15C. Gasoline boils in the range 15 to 150C, lube oil in the range 370 to 525C and so on. Bitumens start to boil in the range C, a typical value being 525C. It is these differences in the boiling ranges for the products that enables them to be separated in an oil refinery on the basis of different boiling points by a process known as fractional distillation. ~40 - ~300 525 -

7 Destilación atmosférica
Queroseno Gasóleo Residuo atmosférico Gas Gasolina 125 °C 150 °C 165 °C 250°C 300 °C 280 °C Crudo Pre-calentado Condensador de agua 7.0 ATMOSPHERIC DISTILLATIONThe first main fractional distillation process in a refinery is carried out at normal atmospheric pressure. That’s why it's called atmospheric distillation. An atmospheric distillation unit is typically about 100' high and about 30' across. Inside the unit are a series of trays forming weirs and there are also take off or sampling points at selected intervals up the column. Pre-heated crude oil enters the unit near the bottom where it is heated to about 300C. At this temperature a lot of the material in the crude immediately boils off and travels as a mixture of gases up the column. The portion of the crude which doesn't immediately boil on entering the column runs to the bottom and out of the unit. This portion is called the atmospheric residue and I'll show you what happens to this in a minute.The mixture of gases which have been formed by the liquid fractions boiling off travel up the column and bubble through the liquids on each tray. As the gases bubble through each tray in turn the heaviest fractions of the gas that is the fractions boiling at the highest temperatures will condense out onto the tray to form liquid. The rest of the gas mixture passes on to the next tray and the process of condensing out the heaviest fraction is repeated all the way up the column.The result of this repeated condensing out successively up the column is that the lowest boiling fractions travel furthest up the column ie gas and gasoline and the heaviest fractions travel the shortest distance up thecolumn ie gas oil. In this way the various fractions are separated out up the column and drawn off at different heights.The process also results in a temperature gradient between the top and bottom of the column corresponding to the different boiling ranges of the various products.Now, the atmospheric residue that is drawn off at the bottom of the unit is quite a soft material, much softer than bitumen. This is because it still contains soft components which because they boil at higher temperatures were not distilled out during the atmospheric distillation process. Unfortunately, we can't remove these higher boiling materials by simply increasing the temperature inside the atmospheric distillation unit. The reason for this is that the higher temperatures needed would decompose the products by a process known as thermal cracking. Instead, a modification of the atmospheric distillation process known as vacuum distillation is used.

8 } Destilación de vacío Condensador de agua 46 °C Vacío 110 °C 185 °C
Destilados de vacío Residuo de vacío (Base para betunes) 46 °C 110 °C 185 °C 260°C 340 °C Residuo atmosférico precalentado Condensador de agua 385 °C Vacío 350 °C (525 °C) } 8.0 VACUUM DISTILLATIONThe vacuum distillation process is exactly the same as atmospheric distillation that I just described except that it is carried out under reduced pressure, typically 40 mm Hg or about 1/20th of normal atmospheric pressure. The use of reduced pressure has the effect of simply reducing the boiling points of the compounds in the atmospheric residue. This is exactly the same as the effect of reduced air pressure up a mountain causing water to boil at a lower temperature.Just as with the atmospheric distillation, vacuum distillation separates the lower boiling materials into fractions which are drawn off at different heights up the column. These vacuum distillates as they're called may be used for lube oil manufacture or may be converted into lighter products such as gas oil or gasoline. The heavy material which doesn't boil off in the vacuum unit, ie the vacuum residue, is drawn off at the base of the column. The run down temperature of this residue is typically 350C but because of the fact it was produced at reduced pressure its true boiling point at normal atmospheric pressure would be of the order of C.By varying the temperature inside the vacuum unit more or less of the lighter materials can be distilled off which results in a harder or softer vacuum residue. A lower distillation temperature will result in a lower yield of vacuum distillates but will produce a larger quantity of a softer vacuum residue. Conversely, a higher temperature increases the amount of distillate produced and a lower yield of a harder vacuum residue is obtained. For some crudes the whole range of paving grades can be produced simply by varying the temperature inside the vacuum unit. However, I've deliberately called the vacuum residue bitumen feedstock and not bitumen because not in all cases can bitumen be made directly from this route and further processing is required which I'll come onto in a minute. Now I don't want to give the impression that bitumen can be made from just any crude oil.

9 Crudos asfálticos Crudos conocidos -1500 Abu Al Bu Khoosh
Alaska North Slope Arab Heavy VS 28 Wafara Burgan Wafra Ratawi Zeit Bay Crudos conocidos -1500 Abu Al Bu Khoosh Airlie Blend Alaska North Slope Alba Amna Zakum Zarzaitine Blend Zeit Bay Zueitina 9.0 CRUDES FOR BITUMEN There are something like 400 different crude oils known at the moment rangeing from Abu al bu Khoosh from the Middle East to Zueitina and of these only about 60 are suitable on their own for making bitumen. So the vast majority of crudes are unsuitable for bitumen manufacture.

10 Variedad de crudos 10.0 BITUMEN CONTENT OF CRUDES
There are two reasons for this : 10.1 The first reason is that the bitumen content of crude oil is very variable. This slide shows the relative amounts of various petroleum fractions obtained by distilling a range of crudes, from very heavy to very light. At the very light extreme we have Gippsland from Australia which contains about 1% bitumen. At the very heavy extreme Vittorio contains over 90% bitumen. Most bitumen producers want to produce other products in addition to bitumen and for this reason Vittorio would not be preferred as a bitumen crude. At the other end of the scale Gippsland contains so little bitumen that it would be uneconomic to use it for bitumen. The most suitable crudes for bitumen production are those in the range from heavy to medium ie Bachaquero to Kuwait although in certain circumstances crudes such as Iranian Light may also be used. 10.2 The second reason that some crudes are not at all suitable for bitumen is due to the basic chemical composition of the crude. As an example of this unsuitability, nearly all crudes from the Far East such as Indonesia and Australia contain a lot of wax. This wax is not completely removed by the distillation process and would be present in significant amounts in the final bitumen. The result would be a poor quality bitumen with poor adhesion to aggregate. For this reason bitumen crudes from the Middle East have to be imported into places such as Australia.

11 Variación del punto térmico para obtener betún de penetración 200
1000+ 610 550 530 460 425 11.0 CUT PT. FOR 200 PEN An alternative way of looking at the differences between heavy and light crudes besides the amount of 200 pen bitumen which may be obtained is the effective distillation temperature or true boiling point required to produce a 200 pen bitumen. This slide shows how the effective distillation temperature varies considerably from crude to crude, with the heavier crudes producing 200 pen bitumen at lower temperatures than lighter crudes. 325

12 Estructura coloidal del betún
Betunes blandos Betunes duros 13.0 BCC OF BITUMEN Although the chemical nature of bitumen is very complicated, work has been carried out on the chemical separation of bitumens using various solvents to show that four main types of material are present. Asphaltenes, resins, cyclics and saturates. Investigations into the chemical and physical behaviour of bitumens indicates that the hard asphaltenes are surrounded by a layer of resins and the two are dispersed in an oily mixture of the saturates and cyclics. Resinas Saturados Asfaltenos Cíclicos

13 Destilación – efectos en la composición
In distillation we separate the bituminous residue from lower boiling point compounds. We can control the consistency of the bitumen by changing the residue cut point - that is the initial boiling point of the bitumen. This chart shows how the bitumen composition changes as we increase our distillation cut point to make harder and harder bitumen. Suppose that we start with 100g of residue. As we distill further, we reduce the weight of residue until here we have about 75g. You can see that distillation removes mostly aromatics and saturates. The aromatics and saturates which remain will have a higher molecular weight that those that were removed - they will be larger molecules, so the viscosity of the bitumen increases. The amount of asphaltenes and resins remains relatively unchanged - about 10g of asphaltenes and 16g of resins. These compounds have very high molecular weight so they do not distill off. As the saturates and aromatics are distilled off, the asphaltenes and resins do become more concentrated, but in percentage terms the increase is small - the asphaltenes may increase from 10% to 13% and the resins from 16% to 21%. So distillation makes bitumen harder by removing volatile compounds and by increasing the viscosity of the maltenes fraction.

14 Estructura coloidal tras la destilación
Betunes blandos Betunes duros

15 Soplado – efectos en la composición
Air blowing makes bitumen harder by significantly increasing the proportion of asphaltenes and probably, in the process, by increasing the molecular weight of the asphaltenes and the resins. It does this at the expense of the aromatics - which are presumably grafted on to the resins and asphaltenes. The amount of saturates remains unchanged. Now we have more asphaltenes floating in the soup of saturates and aromatics - and being polar they will be more likely to interact and form a loose network. The more asphaltenes there are, the more structured the network. This is considered to be a gel structure. However, the viscosity of the saturates/aromatics soup has not been increased significantly by blowing. We still have many of the saturates and aromatics which were present in the soft blower feedstock. So if the asphaltene gel structure is broken down by a shearing action, then the viscosity of the bitumen which we measure will be dominated by the saturates / aromatics. This means that a blown bitumen will tend to be more shear susceptible than a distilled bitumen of the same penetration. We will look at the practical implications in a moment. Blowing is sometimes used to make paving grade bitumens, but this is more properly called air-rectification. The process is used to make a small correction to the bitumen composition. This should not be confused with oxidation which is used to make industrial grade bitumens.

16 Estructura coloidal después del soplado
Betunes blandos Betunes duros

17 Comparación de betunes soplados y destilados
Residuo blando Oriente Medio Destilado Soplado Blowing and distillation can both be used to make bitumens which meet the market specifications, but the two routes result in different compositions. It is interesting to compare bitumens of the same grade made by different routes to see how they differ.

18 Comparación de betunes procedente de diferentes crudos
Residuo blando Oriente Medio Destilado Soplado Crudo 2 Oriente Medio destilado

19 Comparación de betunes soplados y destilados
Blown bitumens are said to age more quickly than distilled bitumens. It is a question of degree. Ageing can be a problem if a large amount of blowing was done, because the blower feedstock was very soft and made at a relatively low cut point. The ageing tendency will show up in an RTFOT test. Air rectification, when used judiciously, can convert a 200 pen soft residue - cut at about 550°C, to a 50 pen grade bitumen which - in terms of composition - falls comfortably within the normal envelope. The air rectification has been used to boost a low asphaltenes content. The saturates and aromatics fractions have been distilled to 550°C. Under such circumstances there is no reason why such a bitumen should age more than a distilled bitumen Soplados

20 Penetración y Punto de Reblandecimiento
Penetración CEN –Especificaciones sobre Punto de Reblandecimiento 1000 Límites CEN 250/330 160/220 100/150 25°C (mm/10) 100 70/100 50/70 40/60 14.0 BS 3690 SPECIFICATIONS ON GRAPH Because I have to advise BP bitumen production sites on processing conditions throughout the world I have to be aware of the all the national specifications which have to be met in all the various countries where BP sells bitumen. The UK is similar to many countries throughout the world in that bitumen is specified by penetration and softening point. I'm sure most of you are familiar with the penetration and softening point limits which appear in BS 3690 but you may not be familiar with this graphical representation of those limits. On this graph I have plotted penetration here and softening point here. The limits for each grade in BS 3690 are represented by dotted lines which form a box. The horizontal lines of each box are the minimum and maximum penetration limits for each grade. So for the 200 pen grade the top line is level with the 230 pen maximum limit and the bottom line is level with the 170 pen minimum limit. The vertical lines are the maximum and minimum limits for the softening point specification for each grade. Again for the 200 pen grade the left vertical line is level with the 33C minimum softening point limit and the right vertical line is level with the 42C maximum softening point limit. A bitumen which has a penetration of 200 and a softening point of 37 can be represented as a point in the middle of the 100 pen specification box. If the penetration were only 171 then the bitumen would be represented as point near the bottom edge of the box. Because both bitumens are represented by points inside the 200 pen specification box they would both meet the spec. for 200 pen. A bitumen with a pen of 50 and a softening point of 40 would be represented by a point here would not lie in any of the specification boxes and would not meet the penetration and softening point limits for any of the grades. So, for a bitumen to comply with the pen and softening point limits in BS 3690 its pen and softening point must fall inside the box for the particular grade. A 450 pen bitumen must fall in this box, a 300 pen in this box, a 200 pen here and so on Those of you who are wondering what the 40 pen grade is here, this is the 40 HD or heavy duty grade. 35/50 30/45 20/30 10 25 30 35 40 45 50 55 60 65 70 75 Punto de reblandecimiento (°C)

21 Curvas de destilación y soplado para betunes de penetración
Penetración CEN – Especificación sobre Punto de Reblandecimiento 1000 Límites CEN 250/330 160/220 100/150 25°C (mm/10) 100 70/100 50/70 15.0 BS 3690 SPECIFICATIONS ON GRAPH INCLUDE BLOWING LINES I'd like to concentrate first on the middle line here on this slide. Instead of putting points representing bitumens from each grade on the graph I have plotted this line passing through each point. This is the line that a bitumen producer would aim for to get all the grades in specification. If the producer is using vacuum distillation to make bitumen he simply varies the temperature inside the vacuum distillation unit to produce softer or harder vacuum residues whose pens and softening points all lie on this line. The distillation can be stopped at any given point to give a bitumen of the required hardness or can be carried on to the temperature or vacuum limits of the unit. In some cases, however, depending on the crude chosen, it is possible that the distillation curve as it's known only just passes through the specification boxes or may even miss one or two. This is where the air blowing route will improve the qualities of the bitumens. Instead of using distillation to harden say a 300 pen vacuum residue and following this line to the left of the boxes, by air blowing the 300 pen vacuum residue it is possible to move the line to the right and bring blown products more into the centre of the specification. As with distillation the blowing process can be stopped at any point along the blowing curve to give the required product. However, unlike the distillation process which may be limited by the capabilities of the distillation unit and can often prevent the harder grades being produced, the blowing process is less restricted and very hard bitumens are able to be made with this process. As with the distillation curve, the blowing curve as it is called is very specific to the particular feedstock being used. If too hard a vacuum residue is used for blowing, the blowing curve will be very similar to the distillation curve and may not modify the products sufficiently. On the other hand, if too soft a residue is used the products could have too high a softening pt. and the blowing curve will pass to the right of the paving grade specification boxes towards the specifications for industrial grade bitumens. The feedstock to the blower must therefore be carefully chosen to ensure that the blowing curve has the right shape to pass through the specification boxes of the grades required. As a slight aside, I did just mention industrial grades. These grades have high softening points for a given penetration relative to paving grades and the specification boxes are to the right of the boxes for paving grades. As you might guess from what I just said, industrial grades are produced by air blowing a very soft residue, usually a vacuum residue fluxed with a vacuum distillate. The very soft feedstock to the blower is carefully tailored so that a very curved blowing line is obtained which passes through the boxes for the industrial grades. 40/60 35/50 30/45 20/30 10 25 30 35 40 45 50 55 60 65 70 75 Punto de Reblandecimiento (°C)

22 Producción de betún Atmospheric distillation Destilado A Crudoil D U
Destilación de vacío V D U Lubricantes etc. Residuo atmosférico Soplado de betún 16.0 BITUMEN PRODUCTION SCHEME This slide just recaps the various stages used in a refinery for making bitumen and other petroleum products and shows schematically how they are integrated. Crude oil is distilled in an atmospheric distillation unit to produce the lighter atmospheric distillates such as gasoline, kerosene and gas oil and also atmospheric residue. The atmospheric residue is further distilled under vacuum in a vacuum distillation unit. The reduced pressure in the vacuum unit is used to reduce the boiling points of the distillates so they are distilled off at lower temperatures. These distillates may be used for lubricants manufacture or converted to lighter products while the vacuum residue may be directly used for bitumen if it is suitable or may be processed further by air blowing to produce the required quality of bitumen. Lubricantes etc. S O P L A D R Fuel óleo Betún Base para betunes

23 Típico esquema de refino para betunes asfálticos de carreteras
Crudo Dest. Atm. Dest. Vac. Residuo 300 pen. Soplado o destilado Mezclador Residuo 300 pen. 25 pen. 17.0 TYPICAL REFINERY SCHEME This slide shows a typical refinery scheme for the production of road bitumens. In principle, all of the grades shown here could be prepared as individual products by distillation or a combination of distillation and blowing. However, to minimise storage requirements and the number of products which must be held at supply temperatures it is usual to not to hold stocks of each of the grades. Instead it is more usual to use the scheme shown here where a soft blending component such as 300 pen vacuum residue and a hard blending component such as 25 pen vacuum residue or blown vacuum residue are the only grades held in stock. These two components are fed to an automatic blending system which is micro-processor controlled to draw the appropriate amounts of the hard and soft blend components from their supply tanks and deliver the grade required directly into the road tanker or rail car. Before being released from the refinery a sample of the bitumen is taken from the road car and is checked for viscosity to make sure that the correct grade is supplied. 300 pen. 200 pen. 100 pen. 70 pen. 50 pen.

24 Gráfico de mezclado para betunes de penetración
10 20 30 40 50 60 70 80 90 100 % peso B 1000 1000 Componente a (blando) (pen a 25°C) Componente B (duro) (pen a 25°C) 100 100 18.0 BLENDING CHART In order to set up the in-line blender as it is called it is necessary to know in advance the proportions of hard and soft component which will produce the bitumen grade required. This is carried out on a regular basis by sampling the hard and soft component tanks and determining the penetrations of the two components. These are then fed into a computer which calculates the proportions of each component required for each grade. If a computer isn't available this blending chart may be used instead. The penetrations of the soft and hard components are put on this blending chart to calculate the proportions required for each grade. As an example, if the soft component is 300 penetration we put a point here and if the hard component is 25 pen we put a point here. These two points represent extreme blends which contain 100% of one or the other component. To determine the amount of each component required for a particular grade the two extreme points are joined by a straight line and where the line cuts the grade required the proportions of each of the soft and hard components may be read off from the scale at the bottom. So in the case of 200 pen the straight line joining the component pens cuts the 200 penetration line here and by dropping down to the bottom axis we see that we require about 17% of hard base and about 83% of soft base. Again for 100 pen we can see that we would about 43% of hard base and about 57% of soft base, and so on. 10 10 100 90 80 70 60 50 40 30 20 10 % peso A

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