NO331801B1 - Process for simultaneous recovery and cracking of oil from oil / solid mixtures - Google Patents

Abstract

The invention relates to a method for simultaneous cracking / upgrading of oil from solid mixtures. The oil containing solids is evaporated in a fluidized bed reactor and the heat of the evaporation is delivered from combustion of a portion of the hydrocarbons. The combustion gases together with the evaporated hydrocarbons act as pneumatic supports for solids. The riser has different diameters so as to achieve acceleration and optimized collisions between the solid particles in the stream.

Description

The present invention relates to a method for "dry" extraction of oil from tar sands (also referred to as oil sands), oil shale and other oil/solid mixtures with upgrading of the oil in the same process. The present patent application is a further development of the discoveries described in the applicant's previous application PCTVNO2007/0170.

Tar sands are found in huge quantities in a number of countries, but the largest deposits are found

in Canada and consists of heavy oil and sand in natural deposits at various depths. These deposits have been the subject of extensive research with the aim of developing technologies to extract the oil from sand. Consequently, a number of different technologies exist.

Alberta's most important mineral resources are oil and natural gas, these make up about 90% of Alberta's extraction income. Alberta produces about two-thirds of Canada's oil and more than three-quarters of its natural gas. Almost half of Alberta's oil is extracted from the large oil sands deposits, which are deposits of heavy crude oil, called bitumen. Alberta's oil sands deposits represent the largest deposits of bitumen in the world. The oil sands deposits are located in three main areas of the province: the Athabasca River Vally in the northeast, the Peace River area in the north and the Cold Lake area in the eastern parts of central Alberta. Bitumen is more expensive to extract than conventional crude oil, which flows naturally and is pumped up from the ground. This is because the thick, black oil must be separated from the surrounding sand and water to produce a crude oil that can be further refined. 1 In the 1950s and 1960s, oil deposits were discovered in other regions, such as the Peace River area and the Swan Hills, south of Lesser Slave Lake. In the late 1960s, the last large oil deposits were found.

Bitumen, unlike normal crude oil found in deep reservoirs, does not have the same light fractions, since these have evaporated over millennia. Bitumen therefore consists of heavy molecules with a density of over 1000 kg/dm<3> (less than 10 API) and has a viscosity that is 1000 times higher than light crude oil. In addition, the tar sands contain over 4% by weight of sulfur and hundreds of ppm of heavy metals. The content of organic material in tar sands can vary from 5% by weight up to 20% by weight, and consequently the extraction of oil from tar sands involves very extensive mass transport.

Due to the composition of the bitumen, it must be upgraded to synthetic crude oil before it can be refined in a refinery for the production of various oil products. Due to the economic potential of these large deposits, a number of processes exist for extracting oil from tar sands. Such technologies include biological, solvent-based, thermal processes and processes where the oil is washed out of the sand using superheated water and which require 430 liters of water for each barrel of oil produced.

Due to the enormous waste products (sand and used, contaminated water) associated with tar sands extraction, the various processes face a number of environmental constraints. In addition, the current technologies produce large amounts of so-called greenhouse gases.

Unlike tar sands, oil shale is shale that contains organic material known as kerogens that cannot be washed or dissolved like bitumen in tar sands. To extract oil from oil shale, it must be heated to a temperature of 500-600°C, whereby the organic material is cracked into liquid products. Like tar sands, oil shale contains a number of undesirable constituents that cause environmental limitations. In the same way as for the extraction of oil from tar sands, a number of different technologies exist for the extraction of oil from oil shale.

The present invention relates to a process which is self-sustaining in terms of energy, where a number of the obstacles of existing technologies have been solved and which, in addition to oil extraction, upgrades the oil to a lighter product than any other existing technologies, removes sulfur to an extent of the order of 40% and heavy metals to an extent of the order of 90% and without the use of water as in the dominant processes. The procedure makes it possible to dispose of dry residual products with limited environmental restrictions since the inorganic material (sand) is disposed of in a dry state.

The present invention therefore provides a method for the simultaneous extraction and cracking/upgrading of oil from solids, such as tar sands, oil shale and other oil/solids mixtures whereby oil-containing solids are injected into a fluidized bed reactor where the hydrocarbons are evaporated, characterized by the heat for the evaporation is delivered by withdrawn gases from the gas flow and which are injected into the reactor plenum and where these gases together with the evaporated hydrocarbons act as a pneumatic carrier for the solids and reduce the partial pressure of the hydrocarbon gases and where the flow is led to a cyclone reactor and further to a separator for solids removal and further to a condensation system for the condensable gases and where the composition of the heated gases is adjusted by adding neutral gases, such as nitrogen, argon, helium, steam and other suitable gases to provide an optimal partial pressure in the reactor for the various the raw materials.

According to a preferred embodiment of the method, the oil-stripped sand is fed to a heat exchanger for preheating the hot gases to be injected into the plenum of the reactor.

According to a preferred embodiment, the method comprises that the gas is drawn off from the process to be heated by heat exchange in an outlet heater heated by means of the outlet from a super heater powered by combustion of oil or gas and oil contained in raw oil sands injected into the super heater.

According to yet another preferred embodiment, the method comprises that the preheated gases from the outlet heater are led to a superheater where they are heated to the desired temperature by heat exchange from burnt oil or gas and oil contained in raw oil sands injected into the superheater.

The following components are included in the method according to the invention:

1. Feed magazine device

2. Fluidizing reactor with

a. start-up burns with

i. Air supply system

ii. Gas supply system

3. Cyclone

4. Sand filter, for example of type "Otto"

5. Solid gas blackens with

a. Sand discharge system

6. Fluidized superheater

a. Start-up burner with

i. Air supply system

ii. Gas supply system

b. Oil injection pump

c. Feed tank/funnel

7. Outlet heat exchanger

8. Exhaust fan

9. Oil condenser with a. Circulation pump

b. Drain pump

10. Oil/water heat exchanger

11. Steam condenser with a. Circulation pump

b. Drain pump

12. Water/water heat exchanger with a. Supply pump for cooling water 13. Decanting device with a. Drain pump for oil

b. Drain pump for water

14. Receiving tank for product with

a. Drain pump

DESCRIPTION OF THE PROCEDURE

As mentioned, the present invention relates to a method for the simultaneous extraction and upgrading of oil from oil sands, oil shale and other particle-oil mixtures (for example sludge) in one operation, without the use of water or steam.

When the process has reached an equilibrium level, shredded oil sands are injected into a vertical reactor where it meets a bubbling layer of hot sand.

Part of the depleted sand can be mixed with the oil sand to homogenize and preheat the raw material.

When the oil sand meets the bubbling hot layer, the oil is stripped off at a temperature of approximately 360°C due to the partial thickness conditions in the reactor caused by the composition of the gas injected into the reactor plenum.

When the oil is stripped in the reactor it undergoes partial cracking due to the thermal and kinetic effects in the reactor and rapid movement by flash evaporation of original water in the sand. As the process is operated at 1.1 bar, superheated steam is produced which, due to the low pressure, expands with force, causing thousands of explosions that generate extreme shear forces between grains of sand on the surface of the bubbling bed, whereby cracking takes place.

The sand is transported pneumatically into a riser by the hot gases injected into the reactor and the oil gas generated in the reactor. The gases injected into the reactor can be the gases formed by the extraction of the oil and water in the oil sands or any type of neutral gas, such as nitrogen, argon or helium or steam. These gases are circulated in the system as described below.

If necessary, part of the produced oil in the oil condenser can be pumped to a hydraulic atomizing nozzle for a second upgrade of the oil.

Due to the low partial pressure of the oil-gas in the reactor, the process can operate at a temperature of approximately 360°C in the reactor. Consequently, the method greatly reduces energy requirements, with consequent reductions in costs and pollution.

The flow of oil-gas, steam from original water in the sand and the injected gas in the reactor is led to a cyclone where the sand is separated from the steam and delivered to a fixed gas heater.

The sand that builds up in the reactor is continuously emptied into the fixed gas heater.

From the cyclone, the gases are fed to a sand filter which removes sand carried from the cyclone. The collected sand in the sand filter is emptied into the fixed gas heater.

The solids-free gases are then transported to a double condensation system. In the first condenser, the oil gas is condensed to liquid oil in the oil condenser and the steam is condensed to water in the steam condenser. This double condensation procedure eliminates the formation of an emulsion, which would have been formed in a single condensation system.

The produced oil is continuously drained from the oil condenser by means of a drain pump to the receiving tank.

The produced water is continuously emptied from the water condenser by means of a drain pump to a decanting device where light oil fractions that have been carried over are pumped off and taken to the receiving tank.

Before the gas enters the oil condenser, part of the gas, which mainly consists of oil gas, is sucked off by means of an extraction fan and injected into an outlet heat exchanger at a temperature of approx. 200°C.

In the outlet heat exchanger, the gas is heated to approx. 250°C and is fed to the fixed gas heater where it is heated to approx. 350°C by extracting heat from the sand injected into the heater.

From the heater, the gas is fed to a fluidized superheater where the gas is heated to approx. 600°C and is led to the plenum in the reactor where the hot gas supplies the energy for the extraction of the oil and water from the sand.

The energy for the fluidized superheater is delivered by burning oil and/or gas and oil contained in the raw oil sands that is injected into the fluidized bed in the heater.

Research and development work has tested the technology in a test where oil sands with an initial quality of 10 API were extracted at 360°C and upgraded in a reactor to 18 API oil and then in the riser to 25 API oil. Upgrading from 10 API to 25 API almost doubles the total value of the oil.

The method according to the invention generates 20-30% less CO2 than existing processes for oil sands extraction.

To optimize collision between the particles to achieve maximum shear forces between the solids in the flow of sand, the gases are accelerated and decelerated in a riser of varying diameter.

The collision between the particles gives rise to a mild hydrogenation of the oil by sonoluminescence of microscopic vapor bubbles trapped between the colliding solid particles. When steam bubbles are caught between irregularities in the moving particles, the steam is subjected to an adiabatic compression whereby the temperature and pressure in the bubble is raised several thousand times above the total temperature and pressure in the process. This causes the water to enter a supercritical state where it breaks down into hydrogen and hydroxyl radicals. Hydrogen, which is absorbed by the heavy oil chains, reduces their bonding, allowing the shock forces of the moving grains and the "explosion" of the microscopic vapor bubbles to crack the hydrocarbon molecules. The main part of the hydrogen is then released and reacts back with the hydroxyl radicals to water, but some of the hydrogen causes a mild hydrogenation of the product.

It is highly desirable to achieve a good sand/oil mixture as early and as quickly as possible. The described method to achieve this requires the aforementioned acceleration and deceleration of the flow. Traditionally, steam is a medium used to maintain fixed bed fluidity and movement in the riser. However, steam has an adverse effect on the very hot solids that occur in the cracking process for the residue. Under these conditions, steam causes hydrothermal deactivation of the catalyst in, for example, FCC crackers.

This is overcome by the present invention by the recycling and heating of part of the gas flow from the fluidized bed reactor which mainly consists of hydrocarbon gases or a mixture of neutral gases as the carrier of the solid substances, which act as a catalyst when cracking the oil.

In order to have the procedure verified, a test rig of 2.5x2.5x3 m was built at SINTEF ENERGIFORSKNING in Trondheim, Norway with a maximum output of 50 kW.

The energy required to process one kilogram of oil sands is given by:

where:

xs = weight part of sand (including metals and sulphur), example 80%

x0 = weight part oil, example 15%

xw= part by weight of water, for example 5%

cs = specific heat for sand kJ/kgK = 1 U/kgK

c0= specific heat for oil at operating temperature kJ/kgK = approx. 2.25 kJ/kgK

r0= heat of vaporization kJ/kg = approx. 225 kJ/kg

dt = temperature difference between operating temperature and feed temperature of sand K H = enthalpy of water at operating temperature kJ/h = 3500 kJ

Operating temperature 360 C = 633 K

The tests were carried out with tar sands from the Athabasca River Vally deposit with the properties indicated above. The following results were obtained:

Density of oil recovered from the fluidizer: 18 API

Density of oil recovered in the riser: 29.3 API

Density of oil drained from the oil condenser: 25.15 API

Residual coke in used sand: .1.25% by weight

Reduction of sulfur in the oil: 45%

Reduction of heavy metals: 87%.

The procedure is described in greater detail with reference to the simplified flow chart in fig.l. A) shows the vertical fluidized bed reactor which has a fluidizing net B) some distance from the bottom of the vessel. The space between the bottom and the fluidized web B) is a plenum C) that receives the hot gases from the fluidized superheater D) which can be powered either by gas and/or extracted oil in addition to the oil and crude oil sands injected into the superheater from the feed tank E) . the hot gases will heat and fluidize the solids (sand) F) contained in the reactor A). The pressure from the hot gases that build up in the reactor will cause the solids and the entrained gases, which consist of steam and hydrocarbon gases, to be transported pneumatically through the riser G) into the reactor cyclone H) which is designed so that, in contrast to conventional cyclones, the solids will be spun around several hundred times in the cylindrical part of the cyclone before they fall down the conical part I) and into a solids gas heater J).

Oil sands are injected into the reactor A) from a feed tank K). The same amount of sand injected into the reactor A), and which is not transferred to the cyclone H), must be withdrawn from the reactor. This is done by the pipe device KK) where the sand is transported to the fixed gas heater J). The cooled sand from J) is emptied at the bottom through pipe KKK).

From the reactor cyclone H) and the sand filter L) the gaseous flow is led to an oil condenser M) which is set at a temperature where the main part of the oil gas is condensed to liquid oil. The gas is condensed with the help of the extracted oil as the oil collected at the bottom of the condenser is pumped with the help of the pump N) through a heat exchanger O) and cooled with the help of water delivered by the pump P). From the heat exchanger O) the cooled oil is led to the top of the condenser and condenses the incoming gases. As the level of oil rises in the condenser, the product is drained off through pipe Q) by means of the pump QP).

The steam is fed to a second condenser R) which is cooled by water injected from the pump P). The steam is condensed by means of the condensed steam as the water collected at the bottom of the condenser is pumped by means of pump PP) through a heat exchanger WH) and cooled by means of the water delivered by pump P). From the heat exchanger WH, the cooled water is fed to the top of the condenser and condenses the incoming steam with associated light oil fractions. Condensed water is drained from the condenser through the pipe S) using the pump SP) and collected in the sedimentation tank T) (settling tank). In the sedimentation tank T), light oil brought over from the steam condenser R) will be decanted off through the pipe U) to a receiving tank V). The water is drained off through the pipe W) to the drain.

Non-condensable components in the condenser R) are discharged through the pipe X) either to air or to a gas cleaning system Y) depending on the local emission requirements.

Part of the product is returned to the riser G) through the pipe NN) by means of a high-pressure pump LL) to the atomizing nozzle S) attached to the riser G).

Before the gas stream after the filter L) enters the oil condenser M), part of the gas is sucked off by means of the extraction ventilator AA) and is led to an outlet heater BB) where the gas is heated by heat exchange of outlet gas from the fluidized superheater

D).

From the outlet heat exchanger BB) the gas is led to the fixed gas heater J) where the gas is further heated by heat exchanged from the sand collected in J).

From the solid gas heater J) the gas is fed to the fluidized superheater D) where the gas is heated to the target temperature by heat exchange from burnt oil and/or gas injected into the heater D) by means of the pump CC) and the combustion of oil in raw oil sands delivered to the heater D) using feed tank E). Used sand from the superheater D) is fed to the fixed gas heater J) via pipe JJ).

From the fluidized superheater D), the hot gases are led to the plenum C) in the reactor A) where they deliver the energy for the process by heat exchange with the injected oil sands from the supply tank K).

By varying the composition of the hot gas, the partial pressure in the reactor can be adjusted to the optimal conditions for different raw materials.

In order to achieve the above-mentioned acceleration and deceleration of the flow in the riser, this can be achieved by giving the riser varying diameters. A preferred embodiment is to form part of the riser as a Laval nozzle where the atomisation nozzle(s) S) are located either in the narrowest part of the ejector or where the ejector starts to expand.

The whole process is a high-intensity thermal process with a high energy density due to the speed of the gas and sand flows. Due to the speeds of the process, the intense heat exchange between sand and oil and the low partial pressure of the hydrocarbon gases caused by the composition of the injected hot gases and produced hydrocarbon gases, the process can operate at a temperature in the range of 300-500°C. Apart from reduced thermal load and energy consumption, this low temperature reduces polymerization of the cracked product.

Start-up of the process is done at the burners DD) and EE) to heat the entire system to a correct process temperature. When the temperature in the various components is reached, the process switches to process mode and the burners are switched off.

Claims (4)

1. Procedure for the simultaneous extraction and cracking/upgrading of oil from solids, such as tar sands, oil shale and other oil/solid mixtures whereby oil containing solids is injected into a reactor with a fluidized bed where the hydrocarbons are evaporated, characterized by the fact that the heat for the evaporation is supplied by withdrawn gases from gas -flow and which is injected into the reactor plenum and where these gases together with the evaporated hydrocarbons act as a pneumatic carrier for the solids and reduce the partial pressure of the hydrocarbon gases and where the flow is led to a cyclone reactor and further to a separator for solids removal and further to a condensation system for the condensable gases and where the composition of the heated gases is adjusted by adding neutral gases, such as nitrogen, argon, helium, steam and other suitable gases to provide an optimal partial pressure in the reactor for the various raw materials. 2. Method for simultaneous extraction and cracking/upgrading of oil from solids, such as tar sands, oil shale and other oil/solid mixtures according to claim 1, characterized in that the oil-stripped sand is fed to a heat exchanger for preheating the hot gases to be injected into the plenum of the reactor. 3. Method for the simultaneous extraction and cracking/upgrading of oil from solids, such as tar sands, oil shale and other oil/solid mixtures according to claims 1 and 2, characterized in that the gas is withdrawn from the process to be heated by heat exchange in an outlet heater heated by means of the outlet from a superheater powered by the combustion of oil or gas and oil contained in crude oil sands injected into the superheater. 4. Method for the simultaneous extraction and cracking/upgrading of oil from solids, such as tar sands, oil shale and other oil/solid mixtures according to claims 1, 2 and 3, characterized in that the preheated gases from the outlet heater are led to a superheater where they are heated to the desired temperature by heat exchange from burned oil or gas and oil contained in raw oil sands injected into the superheater.