GB2187752A

GB2187752A - Process for the production of bitumen

Info

Publication number: GB2187752A
Application number: GB08705828A
Authority: GB
Inventors: Terence Reginald John Fabb
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1986-03-14
Filing date: 1987-03-12
Publication date: 1987-09-16
Also published as: GB8705828D0; GB8606401D0

Abstract

Hydrocarbon feedstocks derived from crude oil and containing at least 1% by wt of a component, which boils below 450 DEG C are blown with a mixture of gas containing free oxygen and an inert stripping gas or vapour, which may be steam. This mitigates the problems associated with bitumens derived from such feedstock, including the adverse effects upon the ageing properties and fume evolution of the bitumen. The process is carried out at 210-280 DEG C and uses 250-1100m<3> of stripping gas per tonne of feedstock.

Description

SPECIFICATION Process for the production of bitumen The present invention relates to a process for the production of bitumen and to the bitumen produced by the process.

Conventional feedstocks for the production of bitumen such as vacuum residues are increasingly being used for producing other, generally higher value, products. There is therefore an incentive to use products from secondary processing, such as residues of cracking processes, as a feedstock for producing bitumen.

Although there is an incentive to use residues from cracking processes as a feedstock for bitumen, the relatively low boiling components in such cracked products have an adverse effect on the ageing properties of the bitumen produced therefrom. The bitumens may also have unacceptable fume evolution when used e.g. in hot mix plants.

The applicants have found that the problems associated with the use of a feedstock containing relatively large amounts of low boiling components to produce bitumens may be overcome or at least mitigated by blowing the feedstock with a mixture of a gas containing free oxygen and an inert stripping gas or vapour.

Thus according to the present invention a process for the production of bitumen comprises blowing a hydrocarbon feedstock derived from crude oil, at least one per cent by weight of which feedstock boils below 450 C, with a mixture of a gas containing free oxygen and an inert stripping gas or vapour, the quantity of the stripping gas or vapour being from 250 to 1100 m3/tonne of bitumen at a temperature of from 210 to 280"C.

The feedstock comprising at least one per cent by weight boiling below 450ec may be selected from one or more of the group comprising: (a) atmospheric reduced crude oil (b) vacuum reduced crude oil (c) a product obtained by thermal or catalytic cracking of an atmospheric or vacuum reduced crude oil (d) a residue obtained by the atmospheric or vacuum reduction of a product of (c).

The feedstock may also comprise a material generally known as a "feedstock modifier" such as, for example, extracts, precipitates and by-products from various petroleum refining processes. The feedstock may, for example, have from 2 to 30%, typically 5 to 20% by weight of components boiling below 450"C.

The inert stripping gas or vapour may be for example N2, CO2 or steam. Steam will generally be the most convenient stripping vapour.

The gas containing free oxygen will generally be air. Other suitable gases include oxygen, oxygen enriched air and ozone.

The volume ratio of the inert stripping gas or vapour to the gas containing free oxygen is typically in the range from 0.1:1 to 10:-1 and is preferably in the range 0.5:1 to 5:1. Typically the quantity of the mixture of gases used is from 500 to 1400 m3/tonne of the bitumen. The blowing time is typically from 0.5 to 5 hrs. The blowing of the feedstock may be carried out continuously or on a batch basis using conventional blowing equipment modified to allow injection of both the oxygen containing gas and the stripping gas or vapour. The temperature at which the feedstock residue is blown is preferably from 230 to 270 C.

The process according to the pesent invention may produce bitumens which meet the standard specifications for bitumens. Such bitumens may be used without further modification.

Alternatively, the bitumens produced according to the invention may be blended with conventionally produced bitumens.

The present invention includes bitumens produced by the process according to the present invention and blends containing these bitumens.

The invention is illustrated by the following examples.

Examples 1 to 3 Three bitumens were prepared by subjecting samples of a feedstock, at least one per cent by weight of which had a boiling point of less than 450 C, to the process according to the present invention.

The feedstock was the bottoms product, i.e. the fraction boiling above 300"C, from the atmospheric distillation of products from the thermal cracking of a mixture of atmospheric and vacuum residues of Forcados and Forties crude oils. Inspection data on the feedstock are given in Table 1.

TABLE 1

Inspection Data on the Standard Test feed stock Method Density at 15 C g/ml 0.968 IP 190/83 Total sulphur content %wt 0.59 IP 336/81 Kinematic viscosity at 60 C cSt 231 IP 71/84 Kinematic viscosity at 82.20C cSt 70.1 IP 71/84 Kinematic viscosity at 100 C cSt 34.6 IP 71/84 Pour point C 33 IP 15/67 Carbon Residue (Conradson) %wt 11.5 IP 13/82 Asphaltenes Content %wt 4.2 IP 143/84 Xylene/Heptane equivalent 51/55 AASHOT-102 Batches of the feedstock were processed according to the present invention in a laboratory bitumen blower. The blower comprised a 7509 capacity vessel, having a sparger positioned adjacent the bottom of the vessel and a dispersator stirrer. An injection line entered through the top of the vessel and ran down to the sparger. The feedstock was charged into the vessel at a temperature of 150"C. Air and water were pumped into the injection line at controlled rates. The hot residue heated the air and vapourised the water as they passed down through the injection line to the sparger. The stirrer mixed the air and steam from the sparger with the feedstock.

The rates of air and water injection, the blowing temperature and the weight of the feedstock initially charged into the blower are given in Table 2 for each of the three Examples. Also given in Table 2 are inspection data for the three batches of bitumen produced.

For comparison; a sample of the feedstock was blown with air in the absence of steam.

Details of this -comparative product are also given in Table 2.

TABLE 2 BLOWING CONDITIONS AND INSPECTION DATA ON BITUMEN PRODUCED

Comparative Examples Product 1 2 3 Air Rate (STP) 1/min 2.0 2.0 2.0 2.0 Steam Rate (STP) 1/min 0 1.9 5.5 5.6 Blowing Temperature C 250 250 250 270 725 718 722 717 Blower Charge g Steam Rate m /tonne - 278 838 781 Total steam and air rate m3/tonne - 570 1143 1060 -------------------------------------------- Penetration at 250C mm/10 42 43 52 45 Softening Point C 93.5 75.5- - 58.5 59.0 Thin Film Oven Test Loss on heating 1.10 0.41 0.21 0.03 Retained pen at 250C mm/10 - 31 1 34 40 - 34 Retained pen at 250C z 74 1 79 - 77 76 Xylene/Heptane equivalent 51/55 41/45 - 46/50 The penetration at 25 C was determined according to standard test method ASTM D5/73 and the softening point was determined according to standard test method lP58/83.The thin film oven test ASTM D1754-78 is intended to give an indication of how the bitumen would perform when mixed with heated aggregates in hot-mix plants. The drop in penetration after 5 hours at 163"C gives an indication of the hardening of the binder during mixing with aggregate.

The results in Table 2 show that the bitumens produced by the process according to the present invention have improved (i.e. reduced) volatility as compared with the comparative product produced by blowing only with air. Also the thin film oven test results show that the bitumens produced according to the invention have better ageing properties than the air-blown comparative product.

The feedstock used in the examples had a xylene equivalent of 51/55. As shown in Table 2, the xylene equivalent was not affected by blowing only with air (comparative product) but was reduced by blowing with air and water (Examples 1 to 3).

Claims

1. A process for the production of bitumen comprising blowing a hydrocarbon feedstock derived from crude oil, at least one per cent by weight of which feedstock boils below 450 C, with a mixture of a gas containing free oxygen and an inert stripping gas or vapour, the quantity of the stripping gas or vapour being from 250 to 1100 m3/tonne of bitumen at a temperature of from 210 to 280"C.

2. A process according to claim 1 wherein the hydrocarbon feedstock is selected from one or more of the group comprising: (a) atmospheric reduced crude oil, (b) vacuum reduced crude oil, (c) a product obtained by thermal or catalytic cracking of an atmospheric or vacuum reduced crude oil, (d) a residue obtained by the atmospheric or vacuum reduction of a product of (c).

3. A process according to claim 1 or claim 2 wherein the feedstock has from 2 to 30% by weight of components boiling below 450"C.

4. A process according to any of the preceding claims wherein the feedstock has from 5 to 20% by weight of components boiling below 450"C.

5. A process according to any of the preceding claims wherein the inert stripping gas or vapour is steam.

6. A process according to any of the preceding claims wherein the ratio of the inert stripping gas or vapour to the gas containing free oxygen is in the range from 0.1:1 to 10:1.

7. A process according to any of the preceding claims wherein the ratio of the inert stripping gas or vapour to the gas containing free oxygen is in the range from 0.5:1 to 5:1.

8. A process according to any of the preceding clams wherein the quantity of the mixture of gases used is from 500 to 1200 m3/tonne of bitumen.

9. A process according to any of the preceding claims in which the temperature at which the feedstock residue is blown is from 230 to 270"C.