Generation ebullated-bed reactor system

Abstract

This invention relates to the conversion or hydrotreatment of petroleum or coal derived liquids in a novel ebullated-bed reactor system. The novel processing scheme results in a much simpler and less costly (investment and annual operating) ebullated-bed reaction system through the elimination of the high pressure, high temperature separator, hydrogen purification plant, and recycle gas compressor as well as a smaller hydrogen make-up compressor all resulting in substantial operational and construction efficiency.

Claims

1. A process for the conversion or hydrotreatment of petroleum or coal-derived liquids comprising: a) feeding one or more liquid hydrocarbon feedstreams and a hydrogen feedstream to a mixing vessel or apparatus wherein said one or more liquid hydrocarbon feedstreams are fully-saturated with hydrogen within said mixing vessel or apparatus and resulting in a mixture that is greater than 90 weight percent liquid phase with the remaining amount undissolved vaporous hydrogen; b) directly processing said mixture that is greater than 90 weight percent liquid phase from said mixing vessel or apparatus in an ebullated-bed reactor for conversion, hydrotreatment, and consumption of hydrogen resulting in a vapor products stream and a liquid products stream; c) routing said vapor products stream for further processing and recovery of liquids and fuel gas; d) routing of a portion of said liquid products stream to an ebullating pump to create an ebullating recycle stream; e) sending a separate portion of said liquid products stream for depressurization and further separation into final liquid and gas products; and wherein said ebullating recycle stream from step d) is one of said hydrocarbon feedstreams from step a).

2. The process of claim 1 wherein said ebullated-bed reactor in step b) contains an extrudate catalyst of at least one-sixteenth of one inch in diameter.

3. The process of claim 1 wherein said ebullated-bed reactor in step b) operates with an ebullation recycle ratio of between 5 to 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) This invention will be described further with reference to the following drawing in which FIG. 1 is a schematic flowsheet of an integrated process with the novel features of the invention described therein.

DETAILED DESCRIPTION OF THE DRAWINGS

(2) FIG. 1 is a detailed schematic flowsheet of the invention. A fresh oil feedstream 10, an optional recycled oil feedstream (e.g. vacuum gas oil or bottoms recycle) 12 and an ebullated-bed recycle oil feedstream 14 are mixed with a hydrogen stream 20 in a simple mixing/contacting vessel/device or apparatus 16. The purpose of this vessel or apparatus 16 is to insure that the hydrogen 20 is dissolved in the liquids at the approximate operating pressure of the reaction system. The mixture 11 from the simple mixing/contacting vessel/device 16 is thereafter fed to the ebullated-bed 30 reactor along with a small hydrogen stream 20a which is added in the case of higher than anticipated chemical hydrogen consumption. In the ebullated-bed reactor 30, the hydrogen 20a readily reacts with the mixture 11 containing the fresh oil feedstream 10, an optional recycled oil feedstream (e.g. vacuum bottoms recycle) 12 and an ebullated-bed recycle oil feedstream 14 using an extrudate type catalyst (not shown).

(3) In the reactor, available gaseous hydrogen can be dissolved in the reactor liquid as the hydrogen concentration falls below the saturation level. The net vapor product 40 from the reactor will contain a low concentration of hydrogen and can be treated downstream to remove acid gases and eventually be routed to LPG and fuel gas recovery (not shown). The net liquid product 50 is thereafter sent to either to an ebullating pump suction device 25 or sent directly to depressurization 54 (i.e., no hot, high pressure separator). Since there is a lower rate of hydrogen feed to the reactor, the make-up compressor will be smaller than a typical compressor used in residue hydrocracking. With no gas recycle there is no HPU (hydrogen purification unit) or recycle gas compressor.

(4) The basis for the quantity of ebullated-bed recycle liquid feedstream 14 rate can be estimated from published hydrogen solubility values. Based on) Cai, H. Y., Shaw, J. M. and Chung, K H., “Hydrogen Solubility Measurements in Heavy Oil and Bitumen Cuts”, FUEL, Vol. 80, 2001, p 1055-1063. Available at http://www.uofaweb.ualberta.ca/jmshaw/pdfs/2001Hydrogensolubilitymeasurementsinheavyoilsandbitumencuts.pdf, the solubility coefficient of typical ebullated-bed feed/recycle is approximately 0.08 g-mole/Kg-MPa at typical residue feedstock reactor temperature and pressure. At typical chemical hydrogen consumptions, Table 1 below illustrates the quantity of total reactor liquid feed and ebullating recycle required for both distillate and residue ebullated-bed applications.

(5) TABLE-US-00001 TABLE 1 Hydrogen Consumption Distillate Residue SCF/Bbl 1,000 1,650 W % 1.62 2.51 g-mole/Kg 8.0 12.4 Pressure, MPa 10 17 Solubility, g-mole/Kg 1.0 1.36 Required Liquid Feed, Kg/Kg 8.0 9.2 Feed Ebullating Recycle Kg/Kg Fresh 7.0 8.2 Liquid Feed
Importantly, the required ebullating pump recycle 14 is in the range of 7 to 8 times the fresh oil feedrate. This is in stark contrast to the 2-3 ratio that is currently evident in state-of-the-art commercial applications.

(6) To accommodate this higher recycle rate the size of the extrudate catalyst can be increased (doubled). This larger catalyst size plus a lower gas velocity in the reactor will double the current ebullating rate requirements (from feed plus recycle of 3.5 to 7.0) resulting in an operation which will provide the required hydrogen. A slightly lower reactor L/D (length to diameter ratio) may also be required.

(7) There is also a potential to lower the reactor operating pressure from the current value of approximately 2,600 psi (residue feed application). Currently the hydrogen outlet partial pressure in the ebullated-bed reactor is approximately 1,900 psi and this is deemed sufficient for stable operation. With the premixing of liquid feeds and hydrogen (˜100%), the total system pressure could presumably be just above the 1,900 psi level and have the same net saturation content of hydrogen.

(8) This invention will be further described by the following example, which should not be construed as limiting the scope of the invention.

Example 1

(9) A 25,000 BPD ebullated-bed facility for hydrocracking a Western Canadian heavy oil is examined to illustrate the large technical and economic potential for the subject invention.

(10) The important base information for the facility is shown in Table 2 below:

(11) TABLE-US-00002 TABLE 2 Feed: Western Canadian Heavy Oil Feedrate: 25,000 BPSD Vacuum Residue Conversion Level: 65 W % Chemical Hydrogen Consumption: 1,170 SCF/Bbl
The important information includes a feedrate of 25,000 barrels per stream day (BPSD) of an Western Canadian Heavy oil and a chemical hydrogen consumption of 1,170 standard cubic feet per barrel of feed (SCF/Bbl), equivalent to 1.7 w % of the feed.
The design and investment/operation cost for this ebullated-bed hydrocracking facility was developed for both a pre-invention and invention cases. It is noted that the operating conditions for the invention case were adjusted so that the net yields of liquid and gas products and product qualities were identical to the pre-invention case.
The investment and operating cost for both cases were developed to determine the potential advantage of the invention. A summary of the cost differential is shown in Table 3 below:

(12) TABLE-US-00003 TABLE 3 Investment, $ MM % Total Pre- US (2015) Invention Cost Reactor −9.8 Mixing Vessel Apparatus +1.0 Larger Ebullating Pump +2.0 Hot High Pressure −1.8 Separation Other Drums/Exchangers −0.3 Hydrogen Purification Unit −12.6 and Gas Purification Net −21.5 7-10 Operating Cost, % Total $ MM/Year (2015) Investment Cost Fired Fuel −0.5 Power- Pumps/Compressor 0.4 Hydrogen −0.7 Net −1.6 5
The example results indicate that the invention will result in an investment savings of approximately 7-10 percent and an annual operating cost savings of 5 percent relative to the pre-invention case. Given that high-pressure residue hydrocracking is capital intensive, these results will significantly impact the profitability of future hydrocracking projects.
The invention described herein has been disclosed in terms of specific embodiments and applications. However, these details are not meant to be limiting and other embodiments, in light of this teaching, would be obvious to persons skilled in the art. Accordingly, it is to be understood that the drawings and descriptions are illustrative of the principles of the invention, and should not be construed to limit the scope thereof.