DE10039575A1 - Method for reducing the amount of pollutants from the exhaust gases of combustion engines running on heavy oil, requires conveying the resultant flue gases over fluidized bed incinerator for steam generation - Google Patents

Abstract

A procedure for reducing the amount of pollutants from the exhaust gas of combustion engines running on heavy oil involves cooling the exhaust gases via a heat displacement e.g. a heat transfer device (12), for preheating of the air and/or steam generation and then supplying the exhaust gases to a stationary fluidized bed incinerator installation (1) before feeding additives and combustible residual fuel and/or the liquid and/or gaseous fuel to the exhaust gases followed by combustion in a temperature range of 850 to 890 degrees C. The generated flue gas is carried freely over the stationary fluidized bed incinerator and then conveyed into additional heat transfer devices for steam generation.

Description

Field of application of the invention

The invention relates to a method and an arrangement for reducing pollutants from the exhaust gases a combustion engine operated with heavy oil for the production of drive and / or heat and / or electrical energy.

The combustion of fuels with considerable pollutant potential, e.g. B. from particularly inexpensive heavy oils with high viscosity and high sulfur content is very interesting from an economic point of view. The negative ecological aspects of this combustion with regard to the quality of the exhaust gases and their composition have so far caused the use of such systems to generate electrical energy and combined heat and power in the energy industry within the scope of the TA-Luft or 13./17 , BImSchV, prevented. Due to the high efficiency of the diesel engines, the fuel consumption is comparatively low, and the CO ₂ emissions are correspondingly lower. Despite this positive property of the diesel engine with regard to the CO ₂ pollution of the atmosphere, the use of such fuels for energy generation could not be realized.

State of the art

A system with combined operation of an internal combustion engine and a vortex is known stratified combustion with circulating fluidized bed (EP 0281535).

Due to the principle of circulating fluidized bed combustion, the possibilities are quality to influence the exhaust gases positively little (Blanke, T., Kremer, H .: Experimental investigations for the formation of pollutants when burning refinery residues in a circulating vortex stratified combustion, VDI Reports No. 1492, 1999).  

The results of this study show that the circulating fluidized bed also has a bottom may have potential for exhaust gas aftertreatment. Due to the principle of the circulation of the layer the reactor is divided into primary and secondary zones. The residence time of the pollutants in the Se secondary zone is almost uncontrollable and mostly very short. This is particularly the case with the Combustion of liquid waste fuels is problematic.

Another disadvantage of this solution is that the hot exhaust gases of the internal combustion engine (the temperature is depending on the combustion process and load of 280 to 550 ° C) must be promoted by a compressor. This fact leads to special designs of the compressor combined with an oversizing due to the low efficiency (high specific compressor work due to the high temperature T _{ab given} ). This reduces the cost-effectiveness and the security of the system in continuous operation.

The principle of circulating fluidized bed combustion requires cyclone separation for the hot ones Particles that make the system significantly more complicated. Another problem for the downstream Teten heating surfaces is that the cyclone's deposition rate is not sufficient for all Separate particles from the gas flow.

The use of internal combustion engines, e.g. B. Diesel engine as a motor for driving so-called "off-road" vehicles, for. B. Ships. However, the use of such engines is becoming increasingly problematic due to increasingly stringent exhaust gas standards and national legislation on the exhaust gas quality of "off-road" engines ((US EPA: US Code, Clean Air Act, 42 USC s / s 7401 et seq. (1970 , 1977 and 1990).) Novellas come into force worldwide for "off-road" pollutant emissions not only for NO _x emissions, but also for SO ₂ emissions and particle or soot emissions, (Sweden EPA : The Environmental Code, 01.01.1999; MAN B Diesel A / S: Emission Control of Two-Stroke Low Speed Diesel Engines, MAN B Paper, 1990).

For these plants, too, the use of a circulating fluidized bed furnace is already in use mentioned reasons not realizable.

Essence of the invention

The object of the invention is simple technology and simple systems construction to find a safe reduction of pollutants from the exhaust gases with a heavy to ensure oil-operated internal combustion engine. This is achieved by inventing according to the exhaust gases by heat displacement, for. B. Heat exchanger for air preheating and / or steam generation, cooled, in a with a temperature control over the amount of fuel operated stationary fluidized bed combustion plant, the exhaust gas additives and combusted bare residues and / or fuels supplied and in a temperature range of 850 to 890 ° C. afterburned, and that the smoke gases generated in this way over a free space of the stationary  Fluidized bed incineration plant and in downstream heat exchangers to the steam generator supply and / or heat extraction can be initiated.

By the invention the combustion of different fuels, including liquid gaseous, pasty, pumpable fuels (waste from the oil processing industry) considerable pollutant potential (high sulfur and residue content) possible. By the pre Proposed procedures are the limit values of the TA-Luft and / or 13./17. BImSchV below and thus a stationary use as a system for generating drive, and / or heat and / or Electrical energy reached.

Description of an embodiment

The invention is explained in more detail using an exemplary embodiment. The drawing shows the Coupling of the internal combustion engine with the stationary fluidized bed combustion system.

The stationary fluidized bed combustion plant 1 consists of reactor 1.3 with a fluidized bed, free space (freeboard) 1.4 , combustion chamber 1.1 with a burner for liquid fuels, discharge and entry devices 1.5 and gas inlet chamber 1.2 .

The internal combustion engine system consists of an internal combustion engine 10 (e.g. two- or four-stroke diesel engine or gas turbine) equipped with a separator, filter, pumps, storage containers and fuel preheater and generator 11 . The turbogenerator plants 4 ; 6 consist of from gas steam generator 5 ; 7 with ash pre-separator, steam drum 4.1 with separator, pumps, turbo generator 4.2 and condenser 4.3 .

The exhaust gas steam generator 5 ; 7 have superheaters ( 5.1 ; 7.1 ), evaporators ( 5.2 ; 7.2 ) and economizers ( 5.3 ; 7.3 ). The stationary fluidized bed combustion system 1 , the air preheater 12 is switched on.

The mode of action is as follows:
The exhaust gases 13 of the internal combustion engine 10 are cooled via the exhaust gas line 8 in the air preheater 12 to a temperature T _ab <T _{dew point in} order to avoid falling below the dew point and thus avoiding acid corrosion. After the air preheater 12 , the exhaust gases 13 are passed by means of the blower 2 into the gas inlet chamber 1.2 , in which a mixing of the exhaust gases 13 with the primary air 14 in front of the reactor 1.3 is made possible. Alternatively, the exhaust gases 13 and the primary air 14 can be supplied separately via separate nozzle systems. Chemical reactions with the pollutant components of the exhaust gas 13 are achieved in a predetermined temperature window in the reactor 1.3 on the principle of the stationary fluidized bed by admixing additives. The flue gases 15 are passed into the exhaust gas steam generator 5 after the treatment in the fluidized bed. In this exhaust gas steam generator 5 , a water vapor mixture is produced in the evaporator 5.2 . In the steam drum 4.1 with separator, the saturated steam is separated from the water and passed over the superheater 5.1 . The steam is expanded in the turbogenerator 4.2 and the mechanical energy is converted into electrical energy in the generator. In the heating condenser 4.3 (cogeneration), the steam is condensed at the outlet from the turbogenerator 4.2 and fed into the steam drum 4.1 in the circuit K1 by means of a feed water pump.

The mechanical energy of the internal combustion engine 10 is converted into electrical energy in the generator 11 . The generation of electrical energy takes place in the circuit K1 and in the Ge generator 11th

The exhaust gas steam generator 7 can be connected upstream of the stationary fluidized bed combustion system 1 . The exhaust gases 13 of the internal combustion engine 10 are introduced into the exhaust gas steam generator 7 via the exhaust gas line 9 . The second steam circuit K2 consists of the exhaust gas steam generator 7 , the steam drum 6.1 with separator, the turbogenerator 6.2 and the heating condenser 6.3 and is ensured by the associated feed water and circulation pumps. From the gases 13 of the exhaust gas steam generator are passed by means of the blower 2 into the gas inlet chamber 1.2 for mixing with the primary air for the fluidized bed. The downstream of the SWSVA water vapor circuit K1 can be carried out as described above (see description of claims 1 and 2). As a result, electrical energy is also generated in the circuit K2. From the circuits K1; K2 can be easily decoupled from district heating.

The introduction of residual fuels (fuels with pollutant potential) in the fluidized bed combustion system is carried out so that the combustion of different gaseous, liquid and / or pumpable and / or pasty substances is made possible. A processing plant for crushing and homogenizing these fuels is not absolutely necessary. The burner in the combustion chamber 1.1 is only required for starting the stationary fluidized bed combustion plant.

The systems and circuits described are equipped with the usual monitoring and control sensors. To ensure starting processes and emergency stops of the systems, bypass devices 16 (on the exhaust side) with corresponding shut-off devices 3 are provided.

The invention combines the advantages of the method of stationary fluidized bed combustion for exhaust gas aftertreatment with the improvement of the overall thermodynamic efficiency of the system. The possibilities for the combustion and optimal energetic use of fuels with considerable pollutant potential in stationary land use are technically and economically possible for the first time for ecological and legal reasons. Due to the better utilization of the heat energy produced, the economy of the method according to the invention increases significantly compared to known technical solutions, and it can be decoupled from the cogeneration. For the first time, technically safe solutions for exhaust gas aftertreatment of engine exhaust gases with a problematic composition combined with a reduction in CO ₂ emissions are made possible.

The invention complies with the legal emission limit values (TA-Luft, BImSchG).

The process-specific requirements for low-emission thermal disposal of liquid and gaseous residual fuels as well as the combustion of fuels with considerable Pollutant potential is that the combination of internal combustion engine and stationary fluidized bed combustion system the exhaust gases of the internal combustion engine in this Aftercare are conducted. This combination also allows combustion under different fuels, such as heavy oils in diesel engines or gas turbines and liquid and / or gas shaped residual fuels in the incineration plant, so that the thermal energy generated with high exploit thermodynamic efficiency. The overall process also results in a increased electricity index. Due to the principle of stationary fluidized bed combustion, the Construction of the plant, in contrast to the circulating fluidized bed, be significantly simplified since the cyclone is not required to separate the particles from the gas flow. To mitigate The risk of erosion in the steam generator are downstream ash pre-separators and / or construction ve measures are provided on the downstream exhaust gas steam generator.

The variable bed height of the stationary fluidized bed incinerator and the targeted addition Specific additives allow all relevant reactions to reduce pollutants in the exhaust gas to run completely in the fluidized bed. This option is particularly important for combustion liquid fuels and combustible residues of great importance. A high efficiency of the Ab building of the pollutants in this case can be achieved before the free space (freeboard).

The invention is applicable for stationary systems on land and mobile systems on ships as well off-road land vehicles for disposal tasks on site without transporting the materials to be disposed of.  

List of reference numbers

1

Fluidized bed incinerator

1.1

combustion chamber

1.2

Gas inlet chamber

1.3

Stationary fluidized bed

1.4

Free space (freeboard)

1.5

Removal and entry devices

2

compressor

3

shut-off valve

4

Turbo generator system (circuit K

1

)

4.1

steam drum

4.2

turbogenerator

4.3

capacitor

5

Exhaust gas steam generator (circuit K

1

)

5.1

superheater

5.2

Evaporator

5.3

economizer

6

Turbo generator system (circuit K

2

)

6.1

steam drum

6.2

turbogenerator

6.3

heating capacitor

7

Exhaust gas steam generator (circuit K

2

)

7.1

superheater

7.2

Evaporator

7.3

economizer

8th

exhaust pipe

9

exhaust pipe

10

Internal combustion engine

11

Electric generator

12

Heat exchanger

13

Exhaust gas (after internal combustion engine)

14

primary air

15

Flue gas (after fluidized bed)

16

Bypass

Claims (7)

1. The method and an arrangement for reducing pollutants from the exhaust gases of an internal combustion engine operated with heavy oil for the production of drive and / or heat and / or electrical energy, characterized in that the exhaust gases via a heat displacement, for. B. heat exchanger for air preheating and / or steam generation, cooled, fed into a stationary fluidized bed combustion plant operated with a temperature control over the fuel quantity, the exhaust gases additives and combustible residual fuels and / or liquid and / or gaseous fuels supplied and in a temperature range from 850 to 890 ° C are burned, and that the flue gases thus generated are passed over a free space of the stationary fluidized bed combustion system and introduced into further heat exchangers for steam generation. 2. The method according to claim 1, characterized in that the exhaust gases via heat dissipation be cooled to generate preheated air and / or steam. 3. The method according to claim 1, characterized in that the exhaust gases and the primary air are introduced into the reactor 1.3 via separate nozzle systems. 4. The method according to claim 1, characterized in that the additives and the combustible from waste materials and / or fuels in liquid and / or pumpable and / or pasty and / or fe ster and / or gaseous form are supplied. 5. The method according to claim 1, characterized in that the exhaust gases via a bypass in the further heat exchangers to be promoted after stationary fluidized bed combustion plant. 6. The method according to claim 1, characterized in that as an internal combustion engine Two- or four-stroke internal combustion engine or a gas turbine is operated. 7. Arrangement for reducing pollutants according to claim 1, characterized in that the Ab gas line of a diesel engine operated with heavy oil via a heat transfer system, z. B. is connected to a stationary fluidized bed furnace, the exhaust duct in a heat and / or steam generator system is integrated.