DD295183A5 - METHOD AND DEVICE FOR PREPARING AND ENERGETICALLY USING SALTS CARBON - Google Patents

Abstract

The invention relates to a method and an arrangement for the technological coupling of process stages of the salt coal processing with process stages whose energetic use. The invention has for its object to develop a method in which the process stages of coals are technically and energetically coupled so that at the same time give maximum energy conversion efficiency and economic efficiency with the energetic usability of this hitherto not dominated combustion energy primary energy carrier. This is inventively achieved in that immediately after the gravity separation of solids such as cokes and ashes from the solid-gas mixture collected in bulk layers and cooled by located in these layers bulk heating surfaces and each discharged in the bed heat for the drying of the raw coal and is used for overheating of the originating from the drying vapor, wherein the superheated vapor drives a vapor condenser, the salt-liberated gas mixture is used in a gas turbine plant and the saline-free cokes recovered from the Salzkohlenaufbereitung are burned in an additional firing of a waste heat boiler, wherein the Waste heat boiler at the same time further degrades the waste heat of the gas turbine plant and generates steam, which drives a steam turbine to generate electricity and that to compensate for the withdrawn with salt cargo solids ash from the coke-fired Zusatzfeue tion and used for water supply of the coupling process recycled vapor condensate. To realize a coke cooler and a raw coal dryer and a known desalting parallel to a known Salzabtriebsreaktor a solid recirculating cooler are set up so that materially and energetically results in a surprisingly advantageous coupling. The tops of the coke and solid cooler are each incorporated into the fuel gas tract, ensure the gravity separation of the solid components from the fuel gas and go steadily into an underlying bottom shaft, in which the cokes or recirculated solids collected after each separation in a bed and cooled become. Fig. {Salt coal; Processing; Coal drying; Gravity separation; Brüdennutzung; Coupling process; Gas-steam combined cycle; Salt operation, thermal; Solids circulation; Alkali vapor condensation; vapor dedusting}

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a method and the associated apparatus for the treatment and energetic use of salt coals on a scale relevant to energy economics.

Characteristic of the known state of the art

The combustion of salt coals in steam generators is attempted at a combustion chamber temperature of 700 to 1600 ^C C, depending on the Feuerungsart realize. During combustion, the alkalis become predominantly volatile and flow in vapor form in the combustion gas through the heating surfaces of the steam generator. Touch the combustion gases, the cold heating surfaces, it comes to the condensation of alkalis, so that deposits arise that hinder the heat transfer. Furthermore, the alkali content of saline coals substantially affects their ash melting process and leads to partial melting already from temperatures of 600 ^e C.

The sticky ash particles form bumps on the tubes of the convection heating surfaces. By further application of solids, such as ash and coke, grows on the way relatively quickly dor free combustion cross-section, the steam generator must be cleaned or taken out of service.

The displacement of the free combustion gas cross-section by solid batch is according to the previously known methods and Devices prevented by the fact that the affected heating surfaces by means of water and steam blower mach 'nlsch cleaned

become. By returning cold Verbrennuogsgasan in the combustion chamber is lowered, the combustion chamber temperature to 800 to 90O ⁰ C.

The aim is to reduce the proportion of salt vapors in the combustion gas. Nevertheless arise in this Temperature range Partial melting of the ash, which leads to beginnings in the Konvektionsheizflächen. With hchem mechanical cleaning this process is used for low salinity coals (Na ₂ O-8%) in

applied to the ashes. For salt coals with an Na? O content of 8 to 26% in the ash, the above-described process is unsuitable. In test facilities for circulating fluidized bed combustion, the combustion chamber temperature can be lowered to 700 ⁰ Cab, also here salt deposits in plant parts, or in bed material agglomeration occurs, which can lead to the restriction of vortex capability to the freezing of the bed. This is due to the up to 600 ⁰ Cmöglichen part melting ashes salty coals. A further reduction of the combustion chamber temperature up to 600 ° C is not useful, since the CO content of the combustion gases is inadmissibly high and the burning of highly water-containing coal is questionable. Furthermore, the optimum conditions for flue gas desulfurization at 850 ⁰ C are not given.

DE-PS 581.55 presents a method and the associated apparatus for the combustion of salt coal, in which between Steam generator and grinding plant & is arranged in degassing shaft, in which the ground coal through Partial combustion of a carrier gas is degassed. The carrier gas used is the degassing gas obtained during degassing. For degassing the temperature range 800-1000 ⁰ C is proposed, with an output of the alkalis from the salt

should be achieved. After the degassing shaft, the coke is separated from the coke-gas mixture and directly as

Fuel passed into the boiler. From the gas to the alkalis by condensation in a heat exchanger, as Special design designed for alkaline cleaning, to be deposited. After that, the gas is either the boiler or

fed to the degassing shaft for combustion. By this output of the alkalis in the degassing shaft with subsequent separation of alkali from the degassing the salt coal use with coke as fuel in a

Steam boiler can be achieved. The disadvantages of this solution are the limited downforce of the alkalis, estimated at 60 ... 70%

the total salt load, in a degassing temperature range of 800-1000 ° C. The limited alkalinity of the alkalis also causes problems in the boiler due to salt deposits on the heating surfaces when the alkali content of the ash is higher than 30-40%

Alkali load remain in the coke. Furthermore, procedural limitations with respect to heat and material balance for the degassing shaft can be expected. To cover the heat demand in the degassing shaft, the process gas is not sufficient, especially if

the salt is to be used as raw coal. It is to be assumed that with it the necessary process temperatures in the

Degassing shaft for a sufficient Alkalalkabetrieb not be achieved. The separation of the alkalis from the gas rope done by cooling in alternately operated heat exchangers. According to available knowledge can be estimated that this principle is not technically feasible, because it, as to the Boiler heating surfaces, constantly polluted by salt separation. Because of the mentioned disadvantages was

this solution proposal so far, not technically realized.

DD 41180 teaches a condensation method including apparatus for salt vapors in combustion gases Combustion of saline coal in steam generators is described as follows: Sand, fly ash or other solids are blown with cold air into the combustion gas stream so that the Condensation of the salt vapors is achieved, so that the alkalis condense on the solid particles. The Realization of this process fails because of the open system of the solids input and its lack of separation from ujm Combustion gas. There are large Feststoffmangen use, thereby the process is uneconomical. By the missing Solids separation after the alkali condensation leads the high solids loading to erosion problems, increased Energy consumption and as a result of lowering the temperature level in the flue gases for Heizflächenvergrößerung. The Adding and mixing the solid in the combustion gas stream according to this solution is considered to be problematic. For the combustion chamber extensive cleaning measures for salt deposits are required. As the alkalis in the Flue gas flow remain, efn part of the problems until the end of the boiler is maintained. A proposed in DD 254058 solution for the energetic use of salty coal includes the alkalis in

a separate reactor with subsequent direct entry of pyrolysis gas and coke into a combustion chamber with circulating

Fluidized bed. As a result, the alkalis are condensed in a desalting reactor. The disadvantages of this invention are

- in the lowering of the temperature level for the heat transfer system of the steam generator with a Heizflächenvergrößerung in consequence;

- The entry of the entire alkali load in the steam generator, Heizflächenschmaubeln by salt deposition can not be completely ruled out;

- In the desalination reactor due to the high volume of flue gas as a result of complete, complete combustion, a large amount of solids for the separation of alkalis is required.

Object of the invention

The aim of the invention is to improve the energetic and economic efficiency of known processes for producing low-alkali fuels from salted coals.

Explanation of the essence of the invention

Dör invention is the object of the invention to provide a method and apparatus for the treatment and energetic use of salt coals, the process stages of treatment not only as a preliminary stage of energetic use then low-alkali fuels, but with process stages of energy use so advantageous connected or integrated, that at the same time maximum conversion efficiency and economic efficiency arise with the energetic utilization of salt coals

 This is inventively achieved in that

- Separated by gravity from alkaline gas containing gas and alkali or alkali-free coke collected in a separation immediately following the bulkhead and by heat transfer to a saturated steam-generating heating surface and a combustion air preheating second heating surface, which are both within the Schuttungsschicht, cooled and then completely one Waste heat boiler is burned with coke additive firing,

- The salt rich raw coal with a grain size of 0 to 6mm in a hopper dryer with integrated fabric filter is pre-dried by heat from heating surfaces in which the saturated steam generated in the coke cooling condenses again and the condensate saturated steam cycle the safety necessary coke cooling energetically with the technological necessary raw coal drying,

- The salty dry coal in a salt driven reactor and there within a fluidized bed for which the combustion air is simultaneously fluidizing medium, partially burned,

- The separated by gravity from the alkali vapor-free gas and laden with alkalis solid collected in a hopper and cooled by heat transfer to the coming from the drying stage dust-free vapors via bed and Wandheizflächen and subsequently recirculated to a desalination reactor, with only a partial flow discharged and by limestone powder and Coke ash is replaced, which initially also a partial sulfur dioxide integration and in the subsequently lower temperature range also ensures the desired salt vapor condensation or sublimation,

- The alumina vapor-freed fuel gas is supplied to a gas turbine plant and the resulting exhaust gas in the waste heat boiler with coke additional firing emits its sensible heat and the ash of the coke additional firing together with limestone flour the solid supplement for the coupled in the desalination reactor solids cycle,

the vapors released from the raw coal carcass and superheated in the solid cooling in a vapor condenser turbine are condensed or consumed as a tapped steam in the preheating of the raw coal and the residual energy content remaining in the condensate is used to preheat the combustion air for the supplementary firing of the gas turbine waste heat boiler,

- Part of the vapor condensate after chemical treatment is used as make-up water for the water-steam cycle, in which the waste heat boiler feeds thermal energy for operating a steam power process.

embodiment

Reference to an exemplary embodiment, the invention will be explained in more detail below. It shows

Fig. 1: a schematic representation.

The salted raw coal 1 with a grain size less than / equal to 6 mm passes through the Brüdenkondensierenden Rohkohlevorwärmer 2 in the pressure-charged hopper dryer 3 with integrated vapor dedusting 4. The saline dry coal 5 with a residual moisture less than / equal to 10% is charged in the fluidized bed of the salt output reactor β, in the a partial combustion, a degassing and a salt output. The degassing gas 7 containing alkali steam carries unburned cocaparticles 8 from the output reactor β into the cyclone-shaped upper part of the coke cooler 9, in which the separation of the coke from the gas, the collection of which takes place in a bed of charge and in this coke cooling. During the cooling of the coke, saturated steam 11, which in turn is used for drying the salt-containing raw coal 1 in the dryer 3, is produced within the heating surfaces 10 located in the bed of slag. Thus, there is an elastic energetic coupling via the condensate saturated steam circuit between coke cooler 9 and raw coal dryer 3. The final stage of Kokskühlung is performed as preheating 12 of the combustion air 13 for the dry coal partial combustion fm output reactor β.

The cyclone-shaped Kokkühleroberteil is connected to the desalting reactor 14, in which the salt-laden gas mixture just separated from the coke is mixed immediately after the entry with the old condensation body serving solid particles. Parallel to the desalting reactor 14, the solid-phase cooler 15 is arranged, at the upper part of which a gravitational separation of the solid particles containing a salt layer takes place from the gas mixture exhaled in the desalting reactor 14, the solid also being transferred in a bed and additionally to it by heat transfer to vapors flowing from the raw coal dryer 3 Wall heating is cooled to recirculate in this state again in the desalting reactor 14, wherein solid portions are tapped with high salt loading 18 and supplemented by coke ash 16 and limestone 17.

In the raw coal preheater 2, followed by a vapor condensate cooling by preheating the combustion air 22 required in the coke-fired additional firing of the waste heat boiler 23 through a gas line 24, the solid is cooler. 1 £ connected to a gas turbine plant 25, the exhaust gases 26 are fed to the waste heat boiler with coke additional furnace 23.

The coke 30 used for the additional firing is the coke discharged from the coke cooler 9. The advantage of this invention is that achieved by integrating the two process stages "salt output" and .Alkalidampfkondensation "as main features efficient salt preparation with process stages immediate energetic linkage and use with the general utilization of the salt and a coupling process efficiency of about 50%, a contribution for SO ₂ emission reduction and only in summary of these components the economic efficiency can be seen.

Claims (2)

1. A process for the treatment and energetic use of salt coals, in which in a first reactor by partial combustion and thus thermally aborted aborted alkalis and in a second reactor, the vaporous alkali components of the gas mixture of circulating and cooled solid particles, characterized in that immediately after the gravitational separation of solids such as cokes and ashes from the solid-gas mixture collected in bulk layers and cooled by located in these layers bulk heating surfaces and each dissipated in the bed heat for drying the raw coal and for overheating of the originating from the drying Brüdens is used, the overheated vapor drives a Brüdenkondensationsturbino, the freed from the salt load gas mixture is used in a gas turbine plant and the salt-free cokes recovered from the salt preparation in a Zu set firing of a waste heat boiler to be burned, the waste heat boiler simultaneously degrades the waste heat of the gas turbine plant and generates steam, which drives a steam turbine to generate electricity and that are used to compensate for the withdrawn with salt cargo solids ash from the coke-fired auxiliary firing and water supply to the coupling process recycled vapor condensate. 2. Arrangement for the treatment and energetic use of salt coals, wherein a Salzabtriebsreaktor a desalting reactor is connected downstream, characterized in that a) is arranged parallel to the Salzabtriebsreaktor (6) a Kokskühler (9) whose upper part is connected to a gas mixture tract which separates by gravity the coke particles from the salt vapor-containing gas mixture, wherein the range of gas-solid separation kontiniuerlich in merges with an underlying shaft, which combines the separated hot solids in a loose bed and at the same time dissipates sensible heat from the bed to an in-bed heating surface (10), which a second combustion air preheating heating surface (12) is arranged downstream of a funnel-shaped Lower part follows, b) parallel to the desalting reactor (14), a solid cooler (15) is arranged, whose upper part is also incorporated into the tract of the gas mixture for the purpose of separating the here with salt freight enriched solid / ash particles, wherein the Wandheizfläche having solid coolers (15) the particles in a Merges the bed, in which a heating surface is arranged and c) parallel to the salt-driven reactor (6) and Kokkühler (9) a raw coal dryer (3) with internal vapor dedusting (4) is arranged, the drying energy from the Kokskühler (9) via a condensate saturated steam circuit (11) as elastic energetic coupling is obtained, the dry coal for the subsequent Salzabtriebsreaktor (6) and produces the vapors dust free for overheating to the arranged above Feststcff ash cooler (15).