FR2464370A1 - DEVICE AND METHOD FOR USING CHARCOAL - Google Patents

Abstract

DEVICE AVOIDING COSTLY STEAM EXHAUST CYCLES. IT INCLUDES A COAL COMBUSTION SYSTEM 2 INCLUDING AN ARRANGEMENT 3 PRODUCING A GASEOUS EFFLUENT FROM THE COAL; A EXPANSION TURBINE 5 COMMUNICATING WITH THIS ARRANGEMENT 3 PRODUCING A GASEOUS EFFLUENT; AND A DEVICE 1, PROVIDING COMPRESSED FLUID, COMMUNICATING WITH THIS COAL COMBUSTION SYSTEM 2, THIS DEVICE INCLUDING A HYDRAULIC COMPRESSOR 6. APPLICATION TO ENERGY PRODUCTION.

Description

The invention relates generally to a central unit

  integrated coal-fired gas turbine, and more particularly

  an integrated plant using a combined cycle

hydraulic / gas turbine.

  Coal-fired power plants are well known. A typical integrated plant comprises a coal combustion system, where a gaseous effluent is produced,

  an expansion turbine driven by the gaseous effluent, and a

  presser that supplies the compressed air used in the coal combustion system. In addition, plants of this type may

  have secondary cycles in which the heat lost

  held in the gases leaving the turbine is used in a heat recovery steam generator, the steam thus produced used to drive a steam turbine generator

  electricity. A description of a plant of the type

  previous in U.S. Patent No. 4,150,953.

  The present invention is an improvement over these conventional types of plants, and this through the use of a hydraulic compressor, with the advantages it presents from the point of view of efficiency in an integrated plant. In addition to increased efficiency, the use described here of a hydraulic compressor saves money by eliminating the cycle

  secondary steam and the mechanical compressor which characterizes

  integrated plants of this type.

  So far, hydraulic compressors have been used

  mainly in air supply systems for

  in the mines, but their use in

  can provide several important advantages over

  the use of a mechanical compressor. In particular,

  hydraulic pressers have isothermal operation and therefore require a significantly lower energy input than compressors

  mechanical, isentropic operation. For example, a com

  Ideal isothermal pressure requires only 70.7% of the energy input.

  necessary to obtain the same level of compression in the isentropic regime when a gas turbine works at

  typical high pressure (eg 10). Moreover, the return

  The actual mechanical compressor is about 84%, while the efficiencies are about 85% for the hydraulic compressor and about 92% for an associated hydraulic pump. This results in a total energy saving of 24% if one uses

  a system, driven by gas turbine, hydraulic pump / com-

  hydraulic presser, (Wah), instead of a gas turbine driven mechanical compressor system, (Wam), as can be seen from the following relationships Wam Wa am 0.84 isentropic Wah (0.92) ( 0.85) Waisotherme Waisotherme. 0.707 W o = 0.76 w W?

  The isothermal regime of the hydraulic compressor also gives

  a low temperature heat sink that can be used

  advantageously in a plant that is jointly owned by the

  lost heat contained in the gases leaving a turbine. nor-

  maliciously, this lost heat is not added to the hot air

  (Approx. 3430C) coming out of an ordinary compressor because the quantity

  The heat remaining in the ejected flow of the system would be insufficient. For example, in such a system, the gases exiting the 5380C turbine could typically exit the system at 371C. Integrated power plants of this type therefore used

  typically expensive cycles of steam exhaustion to

  to gain more from this lost heat from the gas turbine. In addition, these cycles of steam exhaustion required the co-operating combustion system to provide heat for proper operation, and for the gas turbine a reduction of

the heat input.

  The relatively cold compressed air (approximately 380 ° C) delivered by an isothermal hydraulic compressor makes it possible to recover more heat on the gases leaving the turbine; it follows that

  the temperature of the gases leaving the system is limited, essentially

  by the formation of sulfuric acid at about 14 ° C. in an associated heat recovery unit. So we do not need a

  cycle of steam exhaustion. As a result, investment

  relating to the steam cycle and its components

  in the heat transfer disappear. Likewise, the high maintenance costs associated with a steam turbine cycle, as well as those associated with a mechanical compressor, are no longer necessary because the relatively simple hydraulic compressor system uses only a small amount of steam. number of moving parts. In addition, the elimination of the steam turbine steam exhaustion cycle by practicing the present invention makes it possible to provide all of the heat energy available in a particular coal combustion system not to a steam turbine, as in conventional designs, but to the resulting gaseous effluent. (See, for example, "Development of Combined Cycle Combined Cycle Power Plant Projects",

  ASME Publication 77-JPGC-GT-6, by J-R. Petersen and V.H. Lucke).

  Finally, the possibility of having compressed air at

  relatively low temperature by isothermal compression by means of a hydraulic compressor can be used, as described herein, for

  eliminate many of the operational constraints that

  gas turbines pose the presence of impurities associated with coal.

  These impurities are carried by the gaseous effluent from the

  coal combustion system of an integrated power plant and

  trant in a turbine. In particular, alkali metals such

  that sodium and potassium pass in the vapor phase at

  eratures typically encountered in a combustion system of the

  coal. These alkaline impurities can subsequently be

  densities on parts of the turbine, thereby causing corrosion

  parts affected thereby reducing the service life of the

the turbine.

  It is known that the rate of alkaline corrosive attack is highly dependent on the temperature in the operating temperature range of a gas turbine, the corrosion rate decreasing as the temperature drops. Thus, by using the relatively low temperature compressed air provided by a hydraulic compressor to cool the turbine, the temperature of the metal of the affected parts can be lowered, thus reducing the rate of corrosion thereof and within

  acceptable. In addition, compressed air at low temperatures and

  cleanly supplied by a hydraulic compressor can also be sent in flue gas cleaning systems contained in most coal combustion systems to serve as a dilution agent or allow condensation of

  impurities in cleaning systems. The use of a compres-

  The hydraulic system therefore improves the operating conditions of the gas turbine, as well as the overall efficiency of the associated integrated plant. The above advantages of the present invention are obtained in an integrated coal-fired plant; this plant comprises a coal combustion system, an expansion turbine and a device supplying compressed air, equipped with a hydraulic compressor. There is also disclosed a method of using coal in which a gaseous effluent is produced in a coal combustion system fed with compressed air by a hydraulic compressor. The gaseous effluent obtained is sent to an expansion turbine to obtain a usable output energy. In addition, it is advantageous to draw air on the hydraulic compressor to cool the turbine

and clean the gaseous effluent.

  The following description refers to the appended figures

that represent

  Figure 1 and 2 are schematic views of realizations

  possible embodiments of the present invention.

  The invention shown in Figures 1 and 2 comprises a device 1 supplying compressed air to a coal combustion system 2, which system includes an arrangement 3, producing a gaseous effluent in a coal combustion process, and a section 4 cleaning gas for the effluent thus produced. The effluent obtained then relaxes in a turbine

  gas 5 to produce usable work.

  In the device 1, an ordinary hydraulic compressor 6 is used to compress isothermally air sent into the hydraulic compressor via a pipe 7. As described more

  in detail in the document "Hydraulic Air Compressors" ("Compres-

  "), Bureau of Mines Information Circular 7683 (May, 1954), which deals with several typical hydraulic compressor systems, the air (or other possible gas) to be compressed enters under the action of a vacuum in a downwardly flowing column of a fluid such as water and thereby compressed therein, the introduction of the fluid into the hydraulic compressor at a sufficiently high point can be carried out

  using any of a number of methods, including the use of

  use of a motor pump 8, as in the embodiment of the invention of Figure 1, or the use of a direct turbopump 9, as in the embodiment of Figure 2. In both embodiments, the air and the fluid are separated after compression, the outgoing air

  through a pipe 10, and the fluid through a different pipe

ferent 11.

  In the device 1 there is a conventional heat recovery unit

  12, which serves to effectively recover the otherwise lost heat contained in gas ejected from the gas turbine, without the need for an expensive secondary steam turbine cycle, as was typically the case in the past. (See for example "Commercial Power Plant Design Development for the Coal-Fired

  Combined Cycle "(" Development of commercial power plant projects

  [0006] ASME Publication 77-JPGC-GT6, by JR Petersen and VH Lucke.) Cold compressed air entering the heat recovery unit through a pipe 10 passes therethrough in a heat exchange relationship. thermal with the relatively hot gas coming out of the turbine, gas entering the

  recuperator 12 through a pipe 13 and out of a

  14. Thus heated in the recuperator 12, the compressed air

  enters the coal combustion system 2 by means of a

  15. The system 2 air supply is sufficient for

  maintain the temperatures of the combustion system

  below the scaling temperature by sub-products under

ash form of combustion.

  In the embodiment of the invention of FIG.

  hot award winning penetrating coal burning system 2

  enters a combustion chamber 16 with a fluidized bed under pres-

  which is part of the arrangement 3 producing an effluent

  gaseous. The arrangement 3 also comprises a feed system

  conventional 17 bringing into the combustion chamber 16 the

  coal and dolomite used. The combustion chamber itself

  the same is of the classical type; the combustion of coal is done in a pressure chamber containing a fluidized bed of dolomite or limestone whose function is to usefully absorb SOx and NOx emitted in the combustion. However, in this system, all the thermal energy passes into the gaseous effluent, none of which is transferred to a steam turbine; this is what characterized the combined cycles, as Petersen and Lucke show in the article cited above. This feature significantly reduces the cost and complexity of the arrangement 3, and is a major objective of the present invention. The gaseous effluent produced passes from the arrangement 3 to the section 4 for cleaning the gases of the coal combustion system 2 through line 18. In the embodiment of the invention of FIG. 1, the erosive particles are removed from the gaseous effluent in a cleaning section which has a cyclone separator

  conventional 19 and a cyclone separator 20 with an air screen.

  In the present embodiment, the cyclone separator 19 eliminates

  a large part of the harmful particles, while the sepa-

  Cyclone 20 with an air screen removes the finer particles.

  To function properly, the cyclone separator 20 to

  air screen must receive a clean gas stream in addition to the ef-

  fluent gas entering the line 21. In the present invention,

  This clean gas flow comes from the device 1 providing

  compressed air, this device cooperating with a pipe 22.

  The gaseous effluent thus produced is clean; a pipe 23 then makes it pass from the coal combustion system 2 to the

  expansion turbine. 5. If resistant materials are used

  so much corrosion, the pipe 22 can cross

  the combustion chamber 16 and participate in a heat exchange

  to obtain admission temperatures in the

higher turbine.

  In the other possible embodiment of the invention of the figure

  2, the coal combustion system 2 comprises in the

  3 a pressurized fluidized bed gasifier 24 for producing a gaseous effluent. The gasifier 24, of a conventional type, is capable of producing a gaseous effluent of low calorific value when it is supplied with coal and limestone by means of a suitable feed system 25, suitable steam arriving through an inlet 26, and compressed air

  brought by a pipe 27. The gaseous effluent exiting the gasification

  24 by a pipe 28, then passes through a section 4 for cleaning the gases of the coal combustion system 2 which

  carries a cyclone separator 29 for recycling coal, a sepa-

  conventional cyclone 30 and a scrubber 31 alkaline products. The coal particles are removed from the gaseous effluent entering the carbon recycling cyclone separator 29 and return to the gasifier 24 via line 32. The gas is then passed to a conventional cyclone separator where separation of the particles continues. After these first cleaning steps, the gas passes through a scrubber 31 of alkaline products; it removes from the gaseous mixture, by condensation, the corrosive alkaline products present in the form of steam. The scrubber also serves to remove gases from other fine particles so that solid phase alkaline products do not pass through a gas-fired combustion chamber. This characteristic is essential to minimize the production of additional vapors of alkaline products at the higher temperature

  ignition gases in the combustion chamber. It is pos-

  to further improve the elimination of fine particles by

  the use of electrostatic forces.

  A device 33 circulates in the purifier 31

  alkaline products the necessary cooling air. As indicated

  in FIG. 2, the device 33 comprises a pipe 34

  linking the output of the heat recovery unit 12 to an inlet-of the purifier 31. But it should be understood that the cooling air could also reach the inlet of the purifier 31 by a pipe 35 starting from a intermediate point between the hydraulic compressor 6 and the heat recovery unit 12, and this to provide the purifier coolant at lower temperature. After exiting the purifier 31, the heated air is conveyed via line 27 to the gasifier

24 fluidized bed under pressure.

  The coal combustion system 2 of the embodiment of FIG. 2 also comprises a gas combustion chamber 36 which forms part of the arrangement 3 producing a gaseous effluent. The relatively clean qaz coming out of the purifier 31, products

  alkaline by line 37 mixes in the chamber of

  addition to a predetermined amount of compressed air

  preheated in the heat recuperator 12 and

  in the combustion chamber through a pipe 38. A product of gaseous combustion is thus obtained which can be used in the expansion turbine 5, which communicates with the chamber

of combustion 36.

  In the embodiments of FIGS. 1 and 2, a rotor located in

  the expansion turbine 5 rotates when it receives a flow of gas ex-

  suitable pansible. A generator 39, coupled to the turbine, thus produces electric current in a conventional manner. A cooling air line 40 delivers to the turbine 5 air from the hydraulic compressor 6 to cool the turbine parts exposed to the flow of hot gases. In this way, the temperature of these parts drops sufficiently so that

  reduces the corrosive reaction, depending strongly on the temperature

  erated, of any alkaline vapor that might remain in

the gas flow.

  So we realized a method of using coal in

  which air is compressed isothermally in a compressor.

  6. Part of this air is removed to cool

  dir parts of an associated gas turbine, which minimizes alkaline corrosion of these parts. A

  second part of this compressed air is heated up in a

  heat, its initial temperature being lower

  at about 380C and its final temperature reaching about 4540C.

  The heated air then passes through a coal combustion system, where a gaseous effluent is produced and where it is cleaned before reaching the gas expansion turbine, where

  gets a workable output.

  The embodiments of the present invention described above have no purpose other than to give examples; they are not limiting and experts will judge from the foregoing that we can bring to the system and process exposed many substitutions, alterations and modifications without departing from the spirit and scope of the invention. In particular, it is understood that the coal combustion system used in the present invention can comprise any of the numerous arrangements producing a gaseous effluent as well as

  any one of the gas cleaning systems accompanies them

  significant, provided that the resulting gas is suitable for use in an expansion turbine and that the coal combustion system needs a source of compressed air or another

  suitable fluid that can be obtained in a hy-

draulic.

Claims (10)

  1. Device for the use of coal, characterized in that it camprend   - a coal combustion system (2). comprising a   cement (3) producing a gaseous effluent from the coal; an expansion turbine (5) communicating with this arrangement (3) producing a gaseous effluent; and   a device (1) supplying compressed fluid, communicating   as with this system (2) coal combustion, this device   comprising a hydraulic compressor (6).   2. Device according to claim 1, characterized in that the device (1) providing compressed fluid comprises in   in addition to a heat recuperator (12) placed between the compres-   hydraulic system (6) and the coal combustion system (2), this heat recovery unit also being in exchange relation   thermal with the gases leaving the expansion turbine (5).   3. Device according to claims 1 or 2, and   further comprising a member (40) supplying the expansion turbine (5)   in cooling fluid from the device (1) containing compressed fluid.   4. Device according to claims 1 to 3, and   further comprising means (22, 34, 35) for supplying a gas cleaning section (4) belonging to the coal combustion system (2) with fluid exiting the device (1) compressed fluid.   5. Device for the use of coal, characterized in that it comprises - a coal combustion system (2) comprising an arrangement (3) producing a gaseous effluent from the coal and a section (4) for cleaning the coal. gas communicating with this arrangement (3) producing a gaseous effluent; an expansion turbine (5) communicating with this system (2) for burning coal;   a device (1) providing compressed fluid,   with this coal combustion system (2) and includes   a hydraulic compressor (6) and a heat recuperator (12) connected between this hydraulic compressor (6) and this coal combustion system (2), this heat recuperator (12) being in heat exchange relation with the output of this expansion turbine (5); and a member (40) supplying said expansion turbine (5) with   cooling fluid from the device (1) supplied compressed fluid.   A method of using coal comprising compressing gas in a hydraulic compressor (6);   - introducing this compressed gas into a combustion system (2)   coal to interact with the coal contained in the coal combustion system (2); and - producing in this coal combustion system (2) a gaseous effluent and introducing this gaseous effluent into an expansion turbine (5), whereby this turbine is driven and provides a usable job.   7. A method according to claim 6, characterized in that the compressed gas passes through a heat recovery unit (12) to absorb heat before being introduced into the system (2) for burning coal. and in that the gases leaving the expansion turbine (5) are in heat exchange relation with this heat recovery unit (12).   Process according to claim 6 or 7, characterized in   that a portion of the compressed gas is diverted to the turbine at   trigger (5) for supplying it with cooling fluid.   9. Process according to claims 6 to 8, characterized   a portion of the compressed gas is diverted to a gas cleaning section (4) belonging to the combustion system (2) coal.   10. Process according to claim 9, characterized in that   part of the compressed gas passes through, in a heat exchange   part of the coal combustion system (2) to absorb heat, before being diverted to section (4) cleaning of gases.