WO1999050609A1

WO1999050609A1 - Stackable heat exchanger for processing carbonaceous material

Info

Publication number: WO1999050609A1
Application number: PCT/US1999/006234
Authority: WO
Inventors: Edward Koppelman
Original assignee: Koppelman Hillari; KFx Inc
Current assignee: Koppelman Hillari; KFx Inc
Priority date: 1998-03-30
Filing date: 1999-03-22
Publication date: 1999-10-07
Anticipated expiration: 2000-09-30
Also published as: AU3110099A

Abstract

The present invention relates to a heat exchanger apparatus (12) including a plurality of selectively detachable cells (38) to accommodate varying amounts of carbonaceous material to be treated. The invention also relates to systems (10) and processes for removing minerals from the carbonaceous materials and thereafter upgrading the carbonaceous material for use as fuel.

Description

STACKABLE HEAT EXCHANGER FOR PROCESSING CARBONACEOUS MATERIAL

BACKGROUND OF THE INVENTION

The present invention relates to a heat exchange apparatus for

processing carbonaceous materials under variable conditions to effectuate a chemical restructuring of the material. More particularly, the apparatus of the present invention relates to a stackable heat exchanger which is selectively adjustable to treat various amounts of naturally occurring carbonaceous materials, such as wood, peat or sub-bituminous coal, for example, to render them more suitable as solid fuel.

A number of inventions relating to upgrading carbonaceous fuel have heretofore been used or proposed so as to render the carbonaceous fuel more suitable as a solid fuel. Many problems such as extensive costs, both in manufacturing and operating carbonaceous fuel upgrading systems, difficult and complex controls for enabling the operation of carbonaceous fuel upgrading systems particularly on a continuous basis, and a general lack of flexibility and versatility of such equipment both in the adaptation for the processing of other materials at different temperatures and/or pressures and

for replacement of worn components are common.

The apparatus of the present invention is intended to overcome many of the problems and disadvantages associated with prior art equipment and techniques by providing stackable heat exchangers which are of relatively simple design, durable construction, versatile in use and readily adaptable for processing different feed materials under varying temperatures and/or pressures. The apparatuses of the present invention are further characterized as being simple to control and efficient in the utilization of heat energy, thereby providing for economical operation and a conservation of resources.

Particular advantages of the stackable heat exchanger in accordance with the teachings of the present invention include the ability to adjust for increased/decreased production by adding/removing tiers to and from the stack. Additionally, the means for circulating the heat exchange medium are selectively removable independent of each stack tier, unlike conventional long tube heat exchangers. Further, the BTU's obtainable at each tier can be controlled independent of the other tier.

SUMMARY OF THE INVENTION

The benefits and advantages of the present invention are achieved by employing the stackable heat exchanger wherein a predetermined amount of carbonaceous material is charged into at least one section or cell of the heat exchanging apparatus. The heat exchange apparatus comprises at least one tube for circulating a heat exchange medium wherein the tube is disposed within and surrounded by an outer casing. After charging the carbonaceous material into at least one section of the heat exchanging apparatus, a treatment medium such as superheated steam or inert gas for example is introduced into the section containing the carbonaceous material in order to remove undesirable constituents and thereby increase the BTU value of the material. According to a first aspect, the invention provides an apparatus for upgrading carbonaceous material by increasing the BTU value of said material, the apparatus comprising: a stacked heat exchanger including a plurality of selectively detachable cells wherein at least one and preferably each of the cells include means for circulating a heat exchange medium, said means being surrounded by an outer casing which is adapted to receive a charge of carbonaceous material.

By providing a stacked heat exchanger apparatus, the system is readily adaptable to accommodate varying amounts of carbonaceous material. Further, the individual heat exchangers of the stack, otherwise referred to herein as cells, are selectively detachable and therefore replaceable, if necessary, without having to disassemble the entire heat exchanger as is generally the case with conventional long tube heat exchangers useful for treating carbonaceous materials. Further, the relative temperature and pressure can be controlled at each cell if desired to carry out specific treatment objectives.

According to a second aspect, the invention provides a process for upgrading carbonaceous materials, comprising the steps of:

(a) introducing the carbonaceous material into a heat exchanger apparatus comprising a plurality of stacked selectively detachable cells wherein at least one of the cells include an outer casing for receiving the carbonaceous material and selectively removable means for circulating a heat exchange medium throughout the outer casing; (b) introducing a treatment medium into the outer casing containing the carbonaceous material;

(c) treating the carbonaceous material at the desired temperature and pressure for a predetermined amount of time; and (d) removing the upgraded carbonaceous material.

According to yet another aspect of the present invention, the invention provides a process for removing minerals from the carbonaceous materials prior to carrying out the upgrading steps. The process involves introducing the carbonaceous material to an acidic solution to separate out various naturally occurring elements such as calcium and sodium, for example. Once the naturally occurring elements have been removed, the carbonaceous material is ready for upgrading.

Additional advantages and aspects of the invention will become apparent from a reading of the detailed description of the preferred embodiments taken in conjunction with the specific examples and following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a view illustrating a system for carrying out a process for upgrading carbonaceous material in accordance with the teachings of the present invention;

Figure 2 is a partial cross-sectional view of a single heat exchanger which forms part of the stacked heat exchanger assembly in accordance with the teachings of the present invention; Figure 3 is an alternative embodiment of the stacked heat exchanger assembly in accordance with the teachings of the present invention;

Figure 4 is an end view in cross-section further illustrating the heat exchanger assembly of Figure 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Figure 1 , a view is shown illustrating a system 10 employing a stacked heat exchanger assembly 12 in accordance with the teachings of the present invention. The system 10 generally comprises at least one storage bin 14 for housing carbonaceous material prior to upgrading and a water feed 16 to maintain the desired fluid level in feed tube 18.

Disposed within feed tube 18 is an auger 84 driven by motor 20 for transporting carbonaceous material from the feed tube to a second auger 22.

Auger 22 which is driven by motor 24 is attached to the stacked heat exchanger assembly 12 and generally includes an outlet 26 for removing overflow carbonaceous material, if any. Still another auger 28, driven by motor 30, is connected to the stacked heat exchanger assembly 12 along a second end 32 to grind the upgraded carbonaceous material as it exits the stacked heat exchanger assembly. Upon exiting the stacked heat exchanger, the upgraded carbonaceous material is transferred through tube 34 via a

conveyor or auger (not shown) to storage bins 36. Importantly, the system

10 can be operated under either a batch or a continuous process.

Referring to Figure 2, a single heat exchanger cell 38 of the stacked assembly 12 is shown in partial cross-section to more clearly define the structure and optional aspects in accordance with the teachings of the present invention. The cell 38 includes an elongated outer casing 40 which is generally disposed parallel to ground or system supporting surface such that the cell is substantially maintained along a horizontal plane. The cell 38 includes a body portion 42 including a cavity 88 for hosting the carbonaceous material to be upgraded and a selectively removable end cap 44 with the two cell components being operably maintained by at least one, and preferably two, spaced apart releasable retainers 46 disposed over flanges 48 extending outwardly from the casing. The outer casings 40, and more particularly, the body portion thereof, are also provided with one or more sealable inlets 50

and outlets 52 per cell depending mainly on the customers needs. Preferably, the inlets and outlets are sized such that the outer diameter of the inlet corresponds to the inner diameter of a matrix outlet such that the two are joined in a sealed relationship.

As will be appreciated by those skilled in the art, longer cells may include a plurality of inlets and corresponding outlets, in order to accommodate large volume changes whereas shorter ceils with fewer inlets and outlets may be utilized for lesser volume changes of carbonaceous material to be upgraded. Internally, an elongated cell having a plurality of inlets and outlets will generally include a plurality of baffles 54 for segregating the body into multiple treatment zones 56.

The end cap 44 includes an inlet 58 and outlet 60 for introducing a heat exchange medium into the bundle 62 of substantially U-shaped tubes 64 which are welded or otherwise permanently attached to end plate 66 to form the heat exchanger core 74. Preferably, the end plate is of sufficient diameter to seat between the flanges 48 when the end cap and body portion of the cell are coupled together. The inlet 58 and outlet 60 of the respective end caps are connected to conduit system 68 for recycling the heat exchange medium through furnace 70. Extending inwardly from the end cap may be a brace 72 which seats against the end plate 66 to assist in securing the bundle 62 in position, particularly when the system is operated at extreme temperatures and pressures.

Also connected to the stacked heat exchanger assembly 12, as shown in Figure 1 , is a means for introducing and removing a treatment medium as represented by reference numeral 76. The treatment medium which is generally in the form of inert gas and/or superheated steam is introduced through inlet 78 and optionally removed through outlet 80. Although the means for introducing a treatment medium are shown as being cycled through auger 28, it should be understood by those skilled in the art that the means for introducing and optionally removing treatment medium can be

attached to one or more individual cells directly.

Referring to Figures 3 and 4, there is shown an alternative embodiment of a stacked heat exchanger assembly 12A in accordance with the teachings of the present invention. This embodiment which depicts a short stacked heat exchanger is substantially identical to the larger scale heat exchanger assembly shown in Figures 1 and 2 except that each individual cell employs a single inlet and outlet 50A and 52A, respectively, for introducing and removing carbonaceous materials. Optionally, but preferably, the heat

7 exchanger stack 12A is also provided with support members 80A located along each end between adjacent cells to reduce the load subjected upon the joint 82A occurring between the cells.

Although only shown in cross section, rather than employing a plurality of U-shaped tubes to form the heat exchanger core 74A, a single U-shaped tube 64A of significant diameter has been employed. In virtually all other aspects, the construction and operation of the heat exchanger assembly 12A is identical to that shown in Figures 1 and 2.

With regard to the process for upgrading carbonaceous materials, initially the carbonaceous material is optionally washed with an acidic solution having a pH ranging from about 3.0 to about 6.5 and more preferably from about 4.0 to 6.0. The acid included in the solution is selected from the group consisting of hydrochlorine, sulfine, nitric and acetic acids, with acetic acid being preferred. The concentration of the acidic solution should be less than 30%, more preferably, between about 1.0% and 10.0% and, still more preferably, the acidic solution should have a concentration of from about 2.0%

to 4.0%. Preferably, the acidic solution is contained in the portion of the upwardly angled feed tube 18 such that as the carbonaceous material is transferred through the tube toward the heat exchanger assembly, most of the acidic solution and minerals will remain in to the lower portion of the feed tube while the carbonaceous material is transported via auger 84 to the stacked heat exchanger. Once separated from the carbonaceous material, the minerals can be recovered through valve 86.

8 To carry out the upgrading step, the heat exchanger cores 74 are inserted into the respective cells 38 and the body portion 42 and end caps 44 have been coupled together to encapsulate the respective cores. Thereafter, the carbonaceous material is introduced into the heat exchanger cells 38 via auger 22 until the cells are filled to the desired capacity.

With the heat exchanger assembly sealed, the heat exchange medium is circulated throughout the heat exchanger cores 74 and cycled through furnace 70 to heat the carbonaceous material up to about 250° F to about 1200°F. At the same time as the carbonaceous material is being heated, a treatment medium such as superheated steam or inert gas is introduced into the heat exchanger cells to assist in the upgrading process. The treatment medium may be introduced at standard pressures or, depending on the treatment medium being employed, may be introduced at pressures as high as about 3000 psi. After treating the carbonaceous material for a sufficient amount of time, i.e., from about 5 to 30 minutes on average, to obtain a product having increased btu capacity, any by-products generated such as tar for example are removed via the drainage vaive 82. The upgraded carbonaceous material is then transported via auger 28 and through transfer tube 34 to storage bins 36 for eventual use.

As should be understood from a review of the foregoing description, the present invention offers not only a heat exchanger assembly which is selectively adjustable to upgrade a predetermined amount of carbonaceous material by adding or removing tiers to and from the stack, but also offers a convenient means for replacing heat exchanger cells and cores without having to disassemble the entire heat exchanger which is typically the case with standard long tube systems.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the spirit thereof.

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Claims

IN THE CLAIMS:

1. An apparatus for upgrading carbonaceous material comprising: a stacked heat exchanger assembly including a plurality of selectively detachable cells containing a readily replaceable heat exchanger for heating said carbonaceous material and a cavity for hosting the carbonaceous material in proximity to said heat exchanger core, said stacked heat exchanger assembly being adaptable for upgrading various amounts of carbonaceous material by adding or removing cells from the stack.

2. The apparatus of Claim 1 , wherein said cells include a body portion and a detachable end cap.

3. The apparatus of Claim 1 , wherein said cells include an inlet and an outlet with at least one of said inlet and outlet being coupled to a corresponding inlet or outlet on an adjacent cell.

4. The apparatus of Claim 3, wherein said at least one inlet and outlet include mating inner and outer diameters such that said inlet and corresponding outlet are joinable in a sealed relationship.

5. The apparatus of Claim 1 , wherein said heat exchanger core includes a plurality of substantially U-shaped tubes affixed to an end plate.

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6. An apparatus for upgrading carbonaceous material comprising: a stacked heat exchanger assembly including a plurality of selectively detachable cells, said cells comprising a body portion including a cavity for receiving said carbonaceous material, and a detachable end cap and a readily replaceable heat exchanger core disposed within said cavity for heating said carbonaceous material, said stacked heat exchanger assembly being adaptable for upgrading various amounts of carbonaceous material by adding or removing cells from the stack.

7. The apparatus of Claim 6, wherein said cells include an inlet and an outlet with at least one of said inlet and outlet being coupled to a corresponding inlet or outlet on an adjacent cell.

8. The apparatus of Claim 7, wherein said at least one inlet and outlet include mating inner and outer diameters such that said inlet and corresponding outlet are joinable in a sealed relationship.

9. The apparatus of Claim 6, wherein said heat exchanger core includes a plurality of substantially U-shaped tubes affixed to an end plate.

10. The apparatus of Claim 9, wherein the end plate is entrapped between the body portion and the end cap of said cell to assist in maintaining the heat exchanger core in the desired location within the cell.

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11. A system for upgrading carbonaceous material comprising: an apparatus for washing carbonaceous material with an acidic solution to remove minerals; and a stacked heat exchanger assembly including a plurality of

selectively detachable cells containing a readily replaceable heat exchanger for heating said carbonaceous material and a cavity for hosting the carbonaceous material in proximity to said heat exchanger core, said stacked heat exchanger assembly being adaptable for upgrading various amounts of carbonaceous material by adding or removing cells from the stack.

12. The system of Claim 11 , wherein said apparatus for washing carbonaceous material comprises an upwardly extending tube including an acidic solution disposed in the lower portion thereof and an auger for transporting said carbonaceous material through said acidic solution for introduction into said stacked heat exchanger.

13. The system of Claim 11 wherein said acidic solution has a pH of between about 4.0 to 6.0.

14. The system of Claim 11 wherein said acidic solution has a concentration of between about 1.0 to about 10.0%.

15. The system of Claim 11 wherein said acidic solution includes

acetic acid.

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16. A process for removing minerals from carbonaceous materials prior to upgrading, said process comprising the steps of: a) introducing carbonaceous materials containing minerals to an acidic solution; and b) removing the carbonaceous material from said acidic solution upon said minerals from the carbonaceous material.

17. The process of Claim 16 wherein said acidic solution has a pH of between about 4.0 to 6.0.

18. The process of Claim 16 wherein said acidic solution has a concentration of between about 1.0 to about 10.0%.

19. The process of Claim 16 wherein said acidic solution includes

acetic acid.

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