Carbon Black Feedstock from Direct Coal Liquefaction

Abstract

The invention described herein relates to a novel process to create carbon black feed stocks derived from coal by utilizing direct coal liquefaction resulting in an economic process for producing carbon black feedstock. Moreover, relative to the current state of the art (use of FCC slurry oil), the invention process will be significantly more profitable when oil prices increase.

Claims

1. A process for producing carbon black feedstock from a direct coal liquefaction process, comprising: a) feeding a first feed of coal, recycle slurry oil and hydrogen under liquefaction conditions to one or more liquefaction reactors to create a liquid product stream; b) feeding said liquid products stream to an atmospheric fractionator to create a naphtha stream, a diesel stream, a heavy atmospheric gas oil stream, and an atmospheric still bottoms stream, wherein said heavy atmospheric gas oil stream is thereafter recycled back to said one or more liquefaction reactors; c) processing said atmospheric still bottoms stream in a vacuum fractionator to create a light vacuum gas oil (LVGO) stream, a heavy vacuum gas oil stream (HVGO) stream, and a vacuum still bottoms stream, said vacuum still bottoms stream comprising vacuum residue and unconverted coal/ash; and d) utilizing said light vacuum gas oil (LVGO) stream and said heavy vacuum gas oil stream (HVGO) as net carbon black feedstock product.

2. The process of claim 1 wherein there is one liquefaction reactor in step a).

3. The process of claim 1 wherein there are two or more liquefaction reactors in step a).

4. The process of claim 1 wherein the net carbon black feedstock products in step d) has a gravity of less than 1°API.

5. The process of claim 1 wherein the net carbon black feedstock products in step d) has a gravity of less than 0°API.

6. The process of claim 1 wherein the net carbon black feedstock products in step d) has an atomic hydrogen to carbon ratio of 0.98 to 1.02.

7. The process of claim 1 wherein the net carbon black feedstock products in step d) has a distillation end point of less than 1000° F.

8. The process of claim 1 wherein the selectivity of carbon black feedstock products in step d) is greater than forty percent of the total of said naphtha stream and diesel stream from step b) and said light vacuum gas oil (LVGO) stream and said heavy vacuum gas oil stream (HVGO) stream from step c).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a schematic of a coal liquefaction facility using Applicant's process for creating a carbon black feedstock.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In FIG. 1, coal 10 is sent to the coal slurry tank 11 along with recycle oil 40a from the atmospheric fractionation still 18. The recycle oil 40a may also include a vacuum residue and unconverted coal/ash stream 38 from the downstream vacuum fractionation still 24. The slurried coal and recycle oil stream 12 from the coal slurry tank 11 is subsequently sent to the coal liquefaction complex 14 along with hydrogen 7.

[0021] The coal liquefaction complex 14, which includes one or several coal liquefaction reactors operating at high temperature and pressure, creates both gases and liquid products which are routed to downstream purification and separation. The liquid stream 16 is thereafter sent to an atmospheric fractionator 18.

[0022] The atmospheric fractionator 18 separates the liquid stream 16 into a naphtha stream 19, a diesel stream 17, a heavy atmospheric gas recycle oil stream 40 (for example 600 F.°-700 F.°), and an atmospheric still bottoms stream 21. The coproduction of the naphtha stream 19 and diesel stream 17 is a key element of the invention as it provides a large economic benefit in the production of carbon black.

[0023] The heavy atmospheric gas oil stream 40 is thereafter optionally combined with a downstream vacuum residue and a portion of the unconverted coal/ash stream 38 from the vacuum fractionator 24 to create a recycle stream 40a and thereafter sent back to the slurry tank 11 to prepare the coal for liquefaction. This recovered stream 40a is a critical feature of Applicant's invention because it replaces the typical VGO recycle slurry stream and allows for the heavier VGO product to be preserved (not recycled/converted) and result in a maximum yield of carbon black feedstock.

[0024] The atmospheric still bottoms stream 21 is sent to the vacuum fractionator 24 where it is separated into a light vacuum gas oil (LVGO) stream 26, a heavy vacuum gas oil stream (HVGO) stream 28, and a vacuum still bottoms stream 38 comprising vacuum residue and unconverted coal/ash. As mentioned previously, some of the vacuum still bottoms stream 38 is thereafter optionally combined with the heavy atmospheric gas oil stream 40 to create a recycle stream 40a which is fed back to the slurry tank 11. The remaining portion of the vacuum still bottoms stream 38 is fed to a flaker 50 which creates a bottoms product stream 60.

[0025] The LVGO stream 26 and HVGO stream 28 from the vacuum fractionator 24 are combined as feedstock to produce carbon black 29. In a preferred embodiment the selectivity of carbon black feedstock products 29 is greater than forty percent (40%) of the total of naphtha stream 19, diesel stream 17, LVGO stream 26 and HVGO stream 28.

[0026] Product stream 29 will be meet the required carbon black specifications through selection of the ebullated-bed hydrogen partial pressure level and the catalyst inventory and daily replacement ratio. The critical carbon black feedstock inspections are the API gravity (<0°), the distillation end point <1000° F.) and an atomic hydrogen to carbon ratio of 0.98 to 1.02.

[0027] Because of the enhanced selectivity to low-hydrogen containing VGO product, the quantity of hydrogen consumed in the invention coal liquefaction process is significantly reduced relative to the typical DCL Process. This results in improved economics due to lower operating costs and since the coal liquefaction reactors are gas feedrate limited, a higher coal feedrate per reactor train.

[0028] Due to the use of low-cost coal and natural gas feedstocks and the production of significant quantities of valuable naphtha and diesel fuels, the invention results in economics for carbon black feedstock production which are enhanced as the price of oil increases. This is directly opposite to the current carbon black feedstock source/price which are based on the increasing and volatile light oil price.

[0029] This invention will be further described by the following example cases, which should not be construed as limiting the scope of the invention.

EXAMPLE

[0030] A modified DCL facility was designed and economics developed for the production of a carbon black feedstock meeting specifications. The modified DCL Plant operating processes 10,000 STPD (dry basis) of a U.S. bituminous coal. DCL Plant operating conditions relative to the typical DCL conditions are shown in Table 1 below:

TABLE-US-00001 TABLE 1 Modified Typical DCL-Carbon DCL- Black VGO Feedstock Recycle Production Feedrate, STPD (MF) 10,000 10,000 Number of Reactor Stages 2 2 Reactor Temperature T T Reactor Pressure P 0.8 P Catalyst Replacement Rate C 0.3 C

[0031] The yields and product qualifiers from the modified DCL Plant are based on many years of pilot plant and commercial operation and are summarized in Table 2 below:

TABLE-US-00002 TABLE 2 Yields, w % of Moisture and Ash Free (MAF) Coal Gases 17.2 Naphtha 15.6 Diesel 13.7 VGO (Carbon Black Feedstock) 29.1 Unconverted Coal/Heavy Oil 29.1 Total C5 to 1000° F. liquids 58.4 (Naphtha, Diesel, VGO) Hydrogen Consumption, w % 4.7 Selectivity of liquids to carbon black feedstock 49.8% Carbon Black Feedstock (Inspections) Boiling Range, ° F. 700-1000 Gravity, °API 0.1 Atomic Hydrogen/Carbon Ratio 1.0

[0032] The modified facility will produce approximately 29 w % of carbon black feedstock meeting the required specifications. The process therefore has a high (49.8%) selectivity of carbon black feedstock production relative to total liquids (C.sub.5 to 1000° F.). Without the process modifications, the yield of VGO (carbon black feedstock) would be less than 10 w %. Realistic economics of the modified DCL Plant were developed (investment, operating cost, profitability) and evidence a high and increasing IRR (internal rate of return) as the light oil price increases. A break even light oil value at approximately $50/Bbl is indicated, This is shown in FIG. 2 below:

[0033] 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.