DE10047787A1 - Production of fuel gas by total gasification of household waste, pyrolyzes, further gasifies both condensate and coke, then combines all resultant permanent gases - Google Patents

Abstract

Low temperature carbonization gas (4a) produced, which includes permanent gases, is cooled. Hydrocarbons (7b, 9a) in the condensate are further gasified in a heterogenous catalytic process at elevated temperature. They are converted into further permanent gases (26) in the presence of steam. Low temperature coke is converted by partial combustion and partial gasification into permanent gases (28a). All the permanent gases produced are combined. They are purified in a basic (i.e. alkaline) scrubber (8) and following compression, they are mixed with natural gas (16). The fuel gas produced is suitable for energy release, especially in the combustion chambers of gas turbines. Preferred features: Hydrocarbons in the low temperature carbonization gas having condensation temperatures above 70 deg C, are converted. A known heterogeneous high temperature catalyst (26) at 750 deg C-1000 deg C in the presence of steam, is employed. The converted products have condensation temperatures below 70 deg C. The catalyst is in fixed bed form. A known cracking catalyst (6) working at 500 deg C-650 deg C is connected into the low temperature carbonization gas line (5a). This converts the low temperature tars into hydrocarbons with condensation temperatures below 70 deg C. An oily phase (9) is condensed from the low temperature carbonization gases, and is separated from its suspension in wash water. It is sent to the high temperature catalyst, for conversion into permanent gases (26a). Thermal energy from controlled partial combustion of the low temperature coke (3c) is employed in the fluidized bed coke gasifier (25) to bring the catalyst (26) to the required temperature. Controlled partial combustion of the coke takes place in a suitable mixture of oxidant gas and steam, at 900 deg C-1100 deg C, producing permanent gases CO and H2 (26a). Together with the recycled (33) condensates (7b, 9a) of the hydrocarbon compounds, additional quantities of hydrocarbons from various sources are supplied directly to the high temperature catalyst and gasified.

Description

The invention relates to a method for generating fuel gas from household waste and similar wastes by pyrolysis with downstream conversion of the pyro lysis products carbonization gas and carbonization coke in permanent gas.

For the energetic utilization of heterogeneous mixtures, in particular from household waste, biomass and sewage sludge have so far been numerous, however also extremely expensive processes known.

These include
according to DE 43 17 319 the gasification of the entire and specially prepared mixture of waste in rotary grate generators (SVZ Black Pump), the fuel gas generated being used energetically in a combined cycle process,
according to DE 195 12 249, the combined gasification and combustion of the entire waste stream (thermoselect method) using the fuel gas in a gas turbine or a gas engine,
according to DE 41 39 512, the pressure gasification of the entire mixture of wastes in rotary grate generators (Noell-DBI), also with a subsequent combined cycle process,
according to DE 44 20 420 the degassing of waste with subsequent combustion of the pyrolysis gas and coke in a steam boiler (smoldering process from Siemens) and
according to DE 196 52 770 the gasification of solid fuels in the circulating fluidized bed.

The large scope of the system proves to be a disadvantage both for reprocessing of the entry material as well as for material conversion and pollution control.

With the aim of simplification, those efforts have been successful Only pyrolyze waste in rotary kilns and the gaseous and solid py rolysis products in existing coal-fired steam boilers with the main to burn fuel. For example, according to DE 199 25 011 Degassing of waste in a rotary kiln as an upstream system  Power plants, in their steam boilers both the pyrolysis gas and the pyro lysekoks are burned together with the main fuel.

An analogue upstream of this process-technically relatively simple turn furnace for pyrolysis also on gas power processes is because of that in the pyrolysis gas initially contained pollutants in parallel with organic condensates possible but desirable. The task is derived from this fact from the long-chain hydrocarbons in gas produced by pyrolysis convert components that are in the temperature range of the pollutant can no longer condense and maintenance processes, but the energetic utilization remain intact.

Processes for catalytic cracking are known for this, the main ones help to form permanent gases, especially according to DD 248 516, DD 233 583, DD 238 811.

The invention has for its object waste from household and commercial to be treated for their disposal in such a way that, in addition to the fulfillment, vanter requirements the total energy content of the hetero to be disposed of genes used directly in gas power plants and used economically can be.

This is achieved according to the invention in that in addition to the anyway Smelting gas existing permanent gas portion targeted the entire smoldering gas is cooled and the condensates thus obtained from hydrocarbon ver Bonds heterogeneously catalytically at elevated temperature and in the presence of Water vapor is converted into further permanent gases and the smoldering coke by controlled partial combustion / partial gasification in permanent gases as well are transferred and the permanent gas components thus obtained are combined leads, cleaned in a basic wash and after increasing pressure with a Natural gas mixed and so for energy recovery especially by Ga turbines and their combustion chamber is provided.

The waste to be disposed of is warmed up in a known rotary kiln with exclusion of air, dried and pyrolyzed. The smoldering gas that is produced becomes after fine dust removal

• a) a catalytic cracking process in a first catalyst to split tion of the long-chain hydrocarbons contained in the carbonization gas leads, then cooled and washed basic or
• b) immediately cooled with subsequent basic washing,

the cooling and washing in these two process stages as smoldering the condensates from the respective accretions deducted and together with water vapor in a high temperature Catalyst heterogeneously converted into permanent gases.

Furthermore, the smoldering coke that is produced in addition to the carbonization gas is gasified with air and steam in a fluidized bed gasifier, whereby

• a) inte into the carburetor a second high temperature catalyst can be grilled, in this case only sensible heat of the carburetor used to split the pyrolysis gas after the first cracking process remaining short-chain Koh condensed in the pyrolysis gas scrubber hydrogen or
• b) the high-temperature catalyst for heterogeneous catalytic conversion remaining long-chain hydrocarbon compounds externally from the carburetor and then in the separate exhaust line between the be knew natural gas combustion chamber and the pyrolysis rotary tube for the purpose of recording is also classified by sensible warmth.

This second high-temperature catalyst works in a temperature zone rich from 750 ° C - 1000 ° C, belongs to the group of known high temperatures temperature cracking catalysts or high-temperature gasification catalysts and converts the gas scrubbing into an aqueous solution and / or dis persion recycled hydrocarbon compounds in the presence of what serdampf to permanent gases. That is, that contained in the carbonization gas ten hydrocarbon compounds, their condensation temperatures are above about 70 ° C, Catalyst converted into hydrocarbon compounds whose Kon densation temperatures are below 70 ° C.  

The two permanent gas partial streams, the gasification gas and as the gas ka analytical deformation exist, flow to a gas mixing chamber and increase hen there the temperature of the main pyrolysis gas flow from 500 ° C to approx. 600 ° C and thus one for the possibly first cracking process on the Kataly sator required temperature. This first catalyst belongs to the group the known cracking catalysts.

When the gas mixture is cooled, a medium pressure steam is generated and - after subsequent overheating by means of heat from the exhaust gas of the pyroly se rotary tube - the main combustion chamber z. B. a gas turbine or in depend the respective Schwelkoksfeucht as gasifying agent a vortex Layer coke gasifier fed.

The entire gas mixture cooled in this way flows to a basic scrubber to withstand the acid formers SO ₂ , H ₂ S, Cl and F coming from the input material. This scrubber preferably works with a Ca (OH) ₂ suspension. On the wash suspension in the laundry sump, the remaining hydrocarbons condensed out in the washing process float, either as a still remaining portion of the previous catalytic cracking in the temperature range from 500 ° C to 650 ° C and / or as a portion still remaining after the cooling process. These respective condensates from hydrocarbon compounds are returned after collection in the storage tank to the separate or integrated catalytic high-temperature catalytic converter, where they are split into permanent gases and - as already described above - mixed with the dedusted carbonization gas and the coke gasification gas.

A combination of activated carbon downstream of the basic washer and fabric filter ensures heavy metal endurance, so that final ßend the garbage-based now only consisting of permanent gases Compressed gas in two stages with intermediate and post-cooling and z. B. with earth mixed gas is used energetically in a gas power process.

If the high-temperature catalyst between the separate combustion chamber and Pyrolysis rotary tube is classified, there is the possibility, in addition to the reverse condensates from hydrocarbon compounds led to additional amounts of hydrocarbon compounds of different origins (e.g. waste oils and used greases) to feed the high-temperature catalyst directly and in per to convert man gases.  

The following advantages are achieved by the invention:

• 1. The garbage-derived pollutant components are in technology cut fuel gas production endured. As an alternative to flue gas treatment This results in significantly smaller component dimensions.
• 2. The gasification of the smoked coke increases the profitable from the feed re amount of gas, the carburetor itself only for part of the energy Inputs of the amount of waste are to be interpreted.
• 3. The one or the two lying in different temperature windows Catalytic processes ensure the energetic utilization of all tar and oil components of the carbonization gas produced, which otherwise with the on set of gas power processes are condensed out before gas compression would. In addition, there are significant simplifications for the Water treatment because phenols, toluenes and. a. to catalytic high temperature rature conversion are subtracted. Furthermore, the possibility opens up the cooling gas by eliminating a gas quench in the gas scrubber improved energy efficiency.
• 4. The redundant design of the first catalytic cracking stage enables the cyclical burning of the precocci that form during cracking, thus the main process can be operated continuously and the required disposal security can be achieved.
• 5. Gas can be released within a defined range (Wobbe number) Mixing waste and natural gas with the advantage of being mutually substitutable speed, this makes the downstream gas power process completely independent depending on the proportion of organic substances in the garbage input.
• 6. The heterogeneity of the input is hardly subject to heating value restrictions gene because even with larger fluctuations in Mass ratio of gas and coke can be balanced.  
• 7. If the amount of waste fluctuates, the process allows an addition and even a complete substitution of waste input by fossil Fuels - especially dry lignite - can also be used in derar Continuous operation with nominal power is maintained in all cases become.
• 8. Due to the relatively large content of the pyrolysis rotary tube and its stän mixing, the pyrolysis product streams produced are ver gleichmäßigt.
• 9. The process design in the section gas scrubber, water treatment, Sus Pension generation ensures that both the water requirements for Her position of the suspension for the basic gas scrubbing as well as the water required for steam generation for subsequent injection into the gastur bine combustion chamber to be covered by the moisture of the feed material can.
• 10. With upstream of the pyrolysis rotary tube and a temperature control ≦ 550 ° C is achieved that halogen-containing organic substances decomposed without furans and dioxins being able to form again.
• 11. The high temperature working in the temperature window from 750 ° C to 1000 ° C In addition to the conversion, the raturation catalytic converter enables the smoldering process gas-condensed hydrocarbon compounds in permanent gases also the direct feeding of waste oils and / or waste fats, which makes one on the one hand the amount of permanent gas increased and on the other hand the bandwidth recyclable waste materials can be advantageously increased.

Figs. 1 and 2 illustrate optional embodiments of the erfindungsge MAESSEN method.

The following applies to the exemplary embodiment according to FIG. 1:
The household waste to be disposed of and commercial waste similar to household waste as entry well 1 without or also in a mixture with sewage sludge, biomass, dry lignite passes through an entry system not described here into the pyrolysis rotary tube 2 for preheating, drying and degassing.

The energy for this is provided by natural gas firing. The natural gas burner 31 processes the natural gas 16 with preheated combustion air 29 c to a 1250 ° C hot flue gas 31 a, which heats the pyrolysis rotary tube 2 directly and cools down to about 650 ° C and at this temperature via flue gas duct 31 b for steam superheating 17 a and air preheating 17 b is performed before it emits into the atmosphere via flue gas duct 31 c. A discharge device 3 separates pyrolysis crude gas 3 a containing fine dust, which is suctioned off at the top of the discharge device 3 , from the Schwelkoks- metal mixture 3 b, which falls by gravity to the metal holding system 24 . The metals 34 endured here are discharged from the inert atmosphere of the pyrolysis coke system for further use. The smoldering coke 3 c separated from metals reaches the fluidized-bed coke gasifier 25 via a conveying and feeding system (not specified here).

In the hot cyclone 4 , the fine dust contained in the raw pyrolysis gas 3 a, consisting of coke and minerals, is almost completely separated and the fluidized bed coke gasifier 25 is also abandoned via the gas-tight conveyor system 38 . The fine dust 38 a gasified together with the smoldering coke 3 c in the fluidized bed coke gasifier 25 , for which preheated air 29 d and superheated steam 37 were used both as fluidizing media and for the partial combustion and gasification. The generated and fine dust from Mine ralstoff containing gas 25 a is dedusted in the cyclone 28 and then mixed as a further permanent gas portion in the gas mixing chamber 5 with the smoldering gas 4 a. The immersed in the fluidized bed of the fluidized bed coke gasifier 25 high-temperature catalyst 26 operates in the temperature range from 750 ° C to 1000 ° C and splits the short-chain hydrocarbon compounds returned from the gas scrubber 8 via the container 19 in a mixture with water 33 , the water content in the range evaporated below the high-temperature catalyst 26 and is also used as a gasifying agent for the conversion of substances. This catalytic gasification process is supported solely by withdrawing sensible heat from the fluidized bed of the fluidized bed coke gasifier 25 . The resulting permanent gas 26 a is also passed to the gas mixing chamber 5 and mixed there with the gas streams 4 a and 28 a and led into the carbonization line 5 a, consisting of py rolysis gas, gasification gas and catalytic conversion gas. As a result of this mixture, the temperature of the carbonization gas 4 a increases to the required working temperature of the catalyst 6 at about 600 ° C.

The catalyst has two lines with the catalysts 6 a and 6 b to alternately operate one and burn the other from precocci and thus to be able to carry out a continuous process of pyrolysis gas treatment. In the operating catalyst 6 a or 6 b, sulfur tars are broken down into permanent gases that have condensation temperatures down to about 70 ° C.

Hydrocarbons with even lower condensation temperatures ge long in the gas scrubber 8 and condense in the wash suspension 10 so that they float on the wash suspension 10 as an oily phase 9 and can be drawn off from there via a line and returned to the high-temperature catalyst 26 without to burden the process of water treatment in the water treatment plant 21 . In basic gas scrubbing in the gas scrubber 8 , all acid generators such as SO ₂ , H ₂ S, Cl, F are washed out of the gas simultaneously, as salt load with a water content via return line 10 a and a storage tank 20 to the water treatment system 21 and from there ejected for further use, cf. Item 39. The further treated water, which largely comes from the moisture content of the feed material 1 , is used as a gasifying agent for generating the steam required for coke gasification and for producing the suspension 30 required for gas scrubbing. A certain amount of fresh water flow 23 closes the water balance, depending on the volume of water from the moisture of the input material 1 , this fresh water being fed to the suspension treatment 22 . For example, quicklime powder 40 is used as an additive.

Depending on the steam requirement, a deionate 36 is first preheated in the ash ash cooler 27 , so that an inert mixture of substances can be discharged in a cooled manner as the residual product 35 . Deionized water 36 is then as performed before warmed feed water 36 a to the second preheating stage, which is located in the mixed gas cooler 7, then b to the evaporator via line 36, also disposed in the mixed gas cooler 7 and a steam superheater to the steam 17a inside the flue gas cooler 17 and from here directly to the fluidized bed coke gasifier 25 . Depending on requirements, this gasification agent can be used together with the gasification air 29 d for fluidization; if there is no need for this, the steam is blown into the fluidized bed of the fluidized bed coke gasifier 25 above the bottom of the nozzle.

The scrubbed gas mixture 8 a, which only consists of permanent gases, is led via a line from the scrubber 8 to the combined activated carbon / fabric filter 11 and 12 , here cleaned from volatile heavy metals / heavy metal compounds, then compressed in two stages in the compressors 13 via the pressure line 13 a led to the gas mixing chamber 14 and here mixed with natural gas 16 according to the energy requirement of the combustion chamber 15 of the gas power process. In the mixed gas cooler 7 , a medium pressure evaporator is arranged in the middle temperature window, which belongs to a heat transfer system 41 , with the help of which and by means of saturated steam as a heat carrier, a gas heat component is shifted into an air duct and thus for preheating the combustion and gasification air 29 c and 29 d within one first before heat level 18 is used. In this preheating stage 18, the saturated steam condenses and the condensate, which is only slightly supercooled, is returned to the heat source in the mixed gas cooler 7 , evaporated again, etc. For further air preheating, preheater 18 is connected via an air duct to an air preheater 17 b, which the flue gas heat in the lower temperature window of Flue gas cooler 17 transmits to the combustion and gasification air 29 a.

Compared to the exemplary embodiment according to FIG. 1, a further exemplary embodiment according to FIG. 2 contains the following changes:
The mixed gas formed in the gas mixing chamber 5 is fed directly to the mixed gas cooler 7 in the carbonization line 5 a, cooled there to produce saturated steam 36 c and fed into the gas scrubber 8 via line 7 a. The condensing in the cooling process hydrocarbon compounds 7 b are collected in the reservoir 19 and from there together with the remaining in the gas scrubber 8 accumulating hydrocarbon condensates and also with condensed gas moisture to the high-temperature catalyst 26 , which in this case is no longer integrated into the fluidized bed coke gasifier 25 , but is integrated into the separate exhaust gas stream of the natural gas burner 31 and the pyrolysis rotary tube 2 .

Furthermore, process water 36 d is led to the discharge device 3 and used for cooling especially the smoked coke to be discharged together with the inert material 3 b. This coke moisture evaporates in the fluidized bed coke gasifier 25 and subsequently serves at least in part as a gasifying agent for coke gasification. The steam 37 superheated in the steam superheater 17 a is used here for injection into the gas turbine combustion chamber 15 .

In this integration case, the high-temperature catalytic converter 26 has the task of used oils and used greases 1 a as an additional input.

List of the reference symbols used

1

Entry goods (household waste, commercial waste, biomass, sewage sludge, dry lignite)

1

a Waste oils and fats

2

Pyrolysedrehrohr

3

Discharge device of the rotary tube

3

a Raw pyrolysis gas

3

b Smoke coke-metal mixture

3

c Smoke coke

4

cyclone

4

a carbonization gas

5

Gas mixing chamber

5

a carbonization line

6

catalyst

6

a catalyst

6

b catalyst

6

c Mixed gas without long chain hydrocarbons

7

Mixed gas cooler

7

a line

7

b Condensates of high molecular weight hydrocarbon compounds (tars)

8th

basic gas washer

8th

a washed gas mixture

9

oily phase

9

a Condensates of high molecular weight hydrocarbon compounds (oils)

10

Washing suspension with salt loads

10

a Return line for contaminated process water

11

Activated carbon filter

12

fabric filters

12

a Clean gas suction line

13

compressor

13

a pressure line

14

Gas mixing chamber (clean gas with natural gas)

14

a Mixed gas pressure line

15

Combustion chamber of the gas power process

16

natural gas

17

Flue gas cooler

17

a steam superheater

17

b Air preheater in the flue gas cooler

18

Air preheater in the heat transfer system

19

Storage container of a water-hydrocarbon solution / dispersion

20

Storage tank for water to be treated

21

Water treatment plant

22

suspension preparation

23

Fresh water stream

24

Metallaushalteanlage

25

Fluidized bed Koksvergaser

25

a gas

26

High temperature catalyst

26

a Permanent gases

27

Residue ash cooler

28

cyclone

29

Combustion and gasification air

29

a to d preheated combustion and gasification air

30

suspension

30

a upper spray level

30

b lower spray level

31

Natural gas burner for rotary tube heating

31

a flue gas

31

b Flue gas duct to the flue gas cooler

31

c Flue gas duct

32

emitted exhaust gas

33

Mixture of hydrocarbon compounds and water

34

ejected metal

35

residual product

36

deionized water

36

a preheated feed water

36

b Management

36

c saturated steam

36

d Process water for cooling coke and converting it into a gasifier

37

superheated steam

38

conveyor system

38

a fine dust

39

discharged salts

40

Branntkalkmehl

41

Heat transfer system with saturated steam as the heat transfer medium

42

intercooler

43

aftercooler

Claims (7)

1. Process for the production of fuel gas from domestic waste and similar wastes by pyrolysis with subsequent conversion of the pyrolysis products carbonization gas and carbonization coke into permanent gas, characterized in that, in addition to the permanent gas portion already present in the carbonization gas ( 4 a), the entire carbonization gas ( 4 a) is selectively cooled and the condensates obtained in this way from hydrocarbon compounds ( 7 b; 9 a) are converted heterogeneously catalytically at elevated temperature and in the presence of water vapor into further permanent gases ( 26 a) and the smoldering coke ( 3 c) by regulated partial combustion / partial gasification into permanent gases ( 28 a) are transferred and the permanent gas components thus obtained are combined, cleaned in a basic wash ( 8 ) and mixed after a pressure increase ( 13 ) with a natural gas ( 16 ) and thus provided for energy recovery specifically by gas turbines and their combustion chamber ( 15 ) becomes. 2. The method according to claim 1, characterized in that the hydrocarbon compounds contained in the carbonization gas ( 4 a), whose condensation temperatures are above about 70 ° C, by the action of a known heterogeneous high-temperature catalyst ( 26 ) at 750 ° C to 1000 ° C and in the presence of steam in such a form that their condensation temperatures drop below 70 ° C, the high temperature catalyst ( 26 ) being fixed. 3. The method according to claim 1 or 2, characterized in that a working in the temperature range of 500 ° C to 650 ° C catalyst 6 from the group of known cracking catalysts in the carbonization line ( 5 a) is integrated, the smoldering in hydrocarbon compounds with condensation temperatures below 70 ° C. 4. The method according to one or more of claims 1 to 3, characterized in that the gas phases of the sulfur oils further contained in the carbonization gas ( 4 a) are condensed by cooling to an oily phase ( 9 ), this oily phase ( 9 ) from a washing suspension ( 10 ) separated and fed to the high temperature catalyst ( 26 ), the oily phase ( 9 ) being converted into permanent gases ( 26 a) by heterogeneous catalytic conversion. 5. The method according to one or more of claims 1 to 4, characterized in that the thermal energy of the controlled partial combustion of the smoked coke ( 3 c) in the fluidized bed coke gasifier ( 25 ) is used to the high-temperature catalyst ( 26 ) to the necessary Bring temperature level. 6. The method according to one or more of claims 1 to 5, characterized in that the controlled partial combustion of the smoked coke ( 3 c) by a mixture of suitable composition of oxygen or oxygen-containing gases and water vapor at temperatures from 900 ° C to 1100 ° C is, so that, among other things, the permanent gases carbon monoxide and hydrogen ( 26 a) arise. 7. The method according to claim 2, characterized in that together with the by means of the return line ( 33 ) returned condensates ( 7 b; 9 a) the Koh lenwasserstoffverbindungen additional amounts of hydrocarbon compounds of different provenance the high-temperature catalyst ( 26 ) are fed directly and gasified ,