KR101137996B1 - Gas fuel apparatus of LFG - Google Patents

Abstract

The present invention relates to an LFG gas fueling apparatus, comprising: a collecting unit for collecting and fueling LFG gas generated in a landfill, the collecting unit for sucking gas and a first flow of the gas flowing through the collecting unit; A gas filter, a blower for sucking and discharging gas through the collecting unit installed in the landfill, a washing tower for washing the gas flowing through the blower with washing water, and condensation for condensing the cleaned gas through the washing tower. And a moisture drying unit for drying moisture in the gas supplied from the condensation unit, and a first gas filter for removing harmful compounds in the gas passing through the moisture drying unit. The present invention configured as described above can stably capture LFG, improve operating efficiency, and effectively remove hydrogen sulfide, ammonia, and VOC (volatile organic compounds) in the LFG.

LFG, gas filter, condensation, scrubber tower, incineration, stagnation, fuel

Description

Gas fuel apparatus of LFG

The present invention relates to an LFG gas fueling device, and more particularly, to a fueling device for fuelizing a LFG (Landfill Gas) gas generated in a landfill and the like as fuel energy.

In general, wastes brought into landfills are decomposed by various physical, chemical, and biological reactions. Landfill wastes in landfills are composed of various materials. Dissolution and adsorption of inorganic and organic matters by chemical action, chemical reaction, mixture of water and landfills due to physical action, generation of landfill gas and movement of landfill gas occur.

The landfill gas is not only a cause of sea level rise due to global warming, fluctuations in rainfall and structural changes in the ecosystem, but also a human or biohazard.

It contains conditions such as methane gas (CH ₄ ) and inert gas carbon dioxide (CO ₂ ), which can be used as gas fuel in landfill gas or biogas (hereinafter referred to as LFG). It depends on, but accounts for more than 90 mol% of landfill gas. In addition, LFG contains nitrogen, oxygen, moisture, hydrogen sulfide, and many minor harmful components in ppm. Nitrogen and oxygen appear due to air entering the landfill gas collection system or penetrating into the landfill.

Table 1 below shows the LFG chemical properties and gas composition ratio in general.

matter Composition ratio (%) Remarks Methane (CH ₄ ) 50.0 Carbon Dioxide (CO ₂ ) 40.0 Moisture (H ₂ O) 8.12 Other (N ₂ , O ₂ , CO) 1.65 Hydrogen Sulfide (H ₂ S) ppm 50 Ammonia (NH ₃ ) ppm 60 Low calorific value (㎉ / N㎥) 4280 Density (㎏ / ㎥) 0.94 Temperature (C) 30 to 40

Table LFG Composition and Chemical Characteristics The data in Table 1 are approximate LFG reference values, and the composition ratio differs by landfill. The content of methane in typical LFG collected at landfills is approximately 45-55%, and the content of methane for LFG as fuel should be maintained at least 38%.

All but methane are inert gases such as carbon dioxide and water, nitrogen compounds, solid particulates and trace harmful substances. Therefore, in order to use LFG as a fuel, it is necessary to completely remove components other than methane and carbon dioxide, that is, moisture that inhibits combustion, and trace amounts of sulfur compounds, nitrogen compounds, ammonia, and VOC (volatility) that cause corrosion and environmental pollution of equipment. Organic compounds).

As methane formed and discharged from landfills is a source of environmental pollution, it can be collected and disposed of directly, or used as a fuel for landfill gas power generation and cooling / heating facilities. Used as

Particularly, since methane (CH ₄ ) concentration in landfill gas is generally contained more than 50%, it is sufficient to collect and use as alternative energy, but the system technology of the collecting process is weak, and the landfill gas collected and supplied There is not a lot of technology for continuously pretreatment of the gas to suit the utilization equipment, in particular, there is a difficulty in removing the condensate and impurities by cooling and drying the gas.

The present invention for solving the above problems is to provide an apparatus for effectively purifying the LFG gas which is a landfill generation gas to fuel with excellent fuel energy.

In addition, it is an object of the present invention to provide an LFG gas fueling system that can cope with an emergency situation in the process of fueling and has economical performance in consideration of changes in ambient temperature.

According to an aspect of the present invention, there is provided an apparatus for capturing and fueling LFG gas generated in a landfill, comprising: a collecting unit installed in the landfill to suck gas, and a first inlet gas flowing through the collecting unit; A gas filter, a blower for sucking and discharging gas through the collecting unit installed in the landfill, a washing tower for washing the gas flowing through the blower with washing water, and condensation for condensing the cleaned gas through the washing tower. And a moisture drying unit for drying moisture in the gas supplied from the condensation unit, and a first gas filter for removing harmful compounds in the gas passing through the moisture drying unit.

The condensation unit may further include a cooling water supply unit for supplying and circulating the cooling water.

The condensation unit may further include a bypass unit, and when the external temperature is low, the condensation unit may be bypassed through the bypass unit without passing through the condensation unit.

In addition, the incinerator for incinerating the gas introduced by the suction of the brower is characterized in that it further comprises.

In addition, the washing tower, the washing process by continuously spraying the washing water, the contact process of contacting the LFG with the filling material, the process of collecting and forcibly circulating the re-supply of the washing water used in the cleaning process and the circulating cleaning It is characterized by consisting of a process of measuring the pH concentration of the water and circulating the washing water.

The present invention configured and operated as described above can collect the LFG effectively and stably using a brower, and can provide an incinerator to quickly prepare for an emergency so that safe driving can be achieved.

In addition, gas filter (contact type, chemical formula, etc.) is used without installing the adsorption tower used in the past, so it is easy and economical to install and maintain, and it uses condenser to remove moisture and change ambient temperature. Considering the installation of the bypass unit has the advantage that the operating efficiency is improved.

In addition, in the case of a large capacity, by applying a washing tower, hydrogen sulfide, ammonia, and VOC (volatile organic compounds) in the LFG can be effectively removed.

Therefore, the present invention can effectively collect the LFG gas, can improve the safety, which is the most important point of the gasification system to high, there is an effect that can achieve economical operation.

Hereinafter, a preferred embodiment of the LFG gas fueling device according to the present invention with reference to the accompanying drawings in detail as follows.

1 is a schematic configuration diagram of an LFG gas fueling device according to the present invention, Figure 2 is a flow chart showing a fuelization process using the LFG gas fueling device according to the present invention, Figure 3 is a LFG gas fueling device according to the present invention 4 is a block diagram showing the detailed configuration of FIG.

A collecting part 10 installed in a landfill to suck gas, a first gas filter 20 to stagnate the gas flowing through the collecting part, and suctioning and discharging gas to the outside through the collecting part installed in the landfill A blower 30, a washing tower 40 for washing gas flowing through the brower using washing water, a condensing unit 50 for condensing the gas cleaned through the washing tower, and the condensing unit. And a second gas filter 70 for removing harmful compounds in the gas passing through the moisture drying unit.

The collecting unit 10 is installed in the landfill and installed vertically with the landfill ground to collect LFG gas, and is installed by drilling the landfill or vertically installing the collecting pipe from the initial stage of landfilling. In general, vertical perforated pipes are installed over 80% of the landfill from the top of the landfill to the floor. The collecting unit 10 may be applied to a variety of known collecting device will be omitted detailed description.

The first gas filter 20 is primarily used to purify the LFG gas flowing through the collecting unit 10 and performs primary removal of solid fine particles (impurity), hydrogen sulfide, ammonia, and water.

The first gas filter 20 according to the present invention uses a contact filter, which is formed by stacking a plurality of perforated plates in a casing, while the solid particles in the LFG have a specific gravity while the LFG passes through the first gas filter 20. It naturally falls down, and the moisture in the vapor state falls down by condensation after contacting several overlapping perforated plates.

In addition to moisture, traces of ammonia are dissolved in and removed. At this time, the first gas filter connected to the collecting unit is introduced through the inlet LFG installed in the lower gas filter, and passes through the outlet provided in the upper portion through a plurality of perforated plates.

The first gas filter 20 can be used semi-permanently (replacement is not required) by using a plurality of perforated plate using a material resistant to corrosion in accordance with the characteristics of the corrosive LFG, easy to maintain, economical Phosphorus was considered.

The blower 30 is configured to provide a suction force for sucking the LFG through the collecting part 10 embedded in the landfill and a pressure for discharging for the next process, the rear end of the first gas filter 20 It is installed at and supplies suction power.

The blower 30 is provided to adjust the suction pressure in mmAq unit to prevent the inflow of impurities and air in the collecting unit during inhalation, it is possible to collect the LFG of the component ratio usable as fuel. In addition, it is possible to adjust the suction pressure within a certain range according to the state of the collecting part, and it is designed to cope with the surrounding environment (pressure according to the climate, suction pressure fluctuation of the collecting pipe, etc.) in the landfill.

In the case of the LFG collection using the conventional compressor, since suction is constantly suctioned at a higher pressure than the blower 30, it is difficult to adjust the suction according to the state of the landfill, and the air is collected through a collecting pipe close to the device during operation. Since air is sucked in, the concentration of methane mixed with LFG is less than 38%, making it impossible to use it as fuel gas, or the inflow of solid impurities may cause corrosion and failure of equipment.

Therefore, in the present invention, the blower 30 is used for suction collection, and the temperature calculation of the landfill gas compression process is applied and calculated assuming adiabatic compression.

Where K = specific heat coefficient (Cp / Cv), dimensionless number

T ₁ = inlet temperature of the gas, 313 K

T ₂ = outlet temperature of the compressed gas, K

r = gas compression ratio (absolute pressure ratio, P _d / P _s ), dimensionless, 1.68

= 체적 효율, FRACTION, 0.78

= Volumetric efficiency, FRACTION, 0.78

The rate of increase of the outlet temperature of the blower 30 is inversely proportional to the volumetric efficiency and proportional to the size of the gas compression ratio. However, since heat is transferred to the outside by heat transfer, the discharge temperature is lower than the calculated result. According to the actual type of the blower, the differential pressure ΔP between the suction pressure and the discharge pressure is increased by 8 to 12 degrees per 100 mmH 2 O.

The washing tower 40 sprays washing water to remove impurities of the gas passing through the blower.

When collecting large amounts of LFG, it is provided to contact traces of hydrogen sulfide, ammonia, and VOC (volatile organic compounds) in the LFG and spray water to dissolve and remove them. In addition, when the temperature of the rear end of the blower is increased due to a high differential pressure ΔP between the suction pressure and the discharge pressure of the blower 30, it should be installed in consideration of economic efficiency in order to reduce the heat transfer area of the condenser and the capacity of the cooling water supply to be described later. do.

The washing tower 40 is provided with a plurality of spray nozzles are installed in the cleaning process for continuously spraying water, and the contact process for contacting the cleaned LFG with the filling material, the cleaning water used for cleaning is collected again and Forced circulation and supplying again, measuring the pH concentration of the circulating rinsing water, determining whether to supply a new rinsing water, and then circulating.

Depending on the concentration of hydrogen sulfide, ammonia and VOC in LFG, it is possible to use a mixture of chemicals effective for removal.

The LFG is introduced through the lower inlet of the scrubber tower, and after passing through the scrubbing section described above, is transferred to the condenser which is the next process through the upper outlet.

The condensation unit 50 is provided to cool the temperature of the gas to a stable temperature because the high temperature of the gas passing through the blower is a risk of spontaneous ignition.

Since the moisture in the LFG passing through the blower 30 exists in a wet saturated vapor state, the condenser 50 passes through the condenser to lower the temperature of the LFG to a dew point to condense moisture in a saturated steam state. Remove it.

The moisture contained in the LFG may cause combustion disturbance, incomplete combustion, ignition of the device to be used as fuel, or sudden stop, failure and corrosion of the device and piping due to incomplete gas component ratio during operation. The water is removed through the part 50 as much as possible. In addition, traces of hydrogen sulfide and ammonia remaining in the condensation process are dissolved and discharged in condensed water condensed with water to undergo a second removal process through the condensation unit.

The temperature of the LFG passing through the condensation unit 50 is maintained at 5 to 8 degrees, the moisture contained is maintained in a saturated steam of about 92 to 94% removed.

At this time, the cooling water supply unit 51 (Chiller) for supplying the cooling water when condensing the water through the condensation unit is further provided. The cooling water supply unit 51 may condense and remove the water of the LFG flowing into the condensation unit by supplying and circulating cooling water of 8 to 5 ° C. to the condensation unit.

On the other hand, in consideration of the change in the ambient temperature according to the season or region may be further provided a bypass unit 52 that can be bypassed without passing through the condensation unit. In the case of winter or cold regions where the ambient temperature approaches the dew point temperature, the operation of the condenser is stopped, and the inlet and the outlet of the condenser are connected to the bypass unit 52. The saturated vapor LFG passing through the brower is removed by condensation of water in the pipe to the water drying unit 60 which will be described later. In addition, the temperature of the gas can be maintained at a low temperature without the condensation unit by the external temperature.

The moisture drying unit 60 removes the moisture in the LFG by drying using a moisture dryer (De-humidifier). The temperature of the LFG passing through the condensation unit is 8 to 5 ℃, the water content is less than 0.7% saturated steam. The moisture drying unit removes and expands the 0.7% steam remaining in the LFG and expands it, and properly adjusts the temperature of the gas required as fuel by the LFG such as a power generation facility 120 and a storage facility 130 such as a generator and a boiler. It is provided to raise and supply.

The operating temperature of the moisture drying unit should be installed to maintain 50 to 80 ℃ in consideration of the temperature drop for the pipe length to the power generation facility or storage facility. In any case, the temperature should be maintained above 50 ℃ and the moisture content should be lowered below 0.3% by drying. After passing through the water dryer, the LFG is in a saturated steam state close to the dry air, and the moisture in the LFG is decomposed and removed by drying, and the remaining water is maintained in the expanded saturated steam state by heating.

The second gas filter 70 finally removes a small amount of harmful compounds (hydrogen sulfide, VOC, etc.) remaining in the LFG passing through the moisture drying unit. In the existing methods of adsorption of activated carbon, there is a high maintenance cost and the possibility of explosion or secondary pollution due to concentration. Therefore, the second gas filter using micro, ceramic, bio filter, etc. can be used more economically and effectively. Hazardous compounds can be removed. At this time, an effective gas filter should be selected according to the composition ratio of harmful compounds in LFG, and it can be installed by mixing with chemical gas filter.

In addition, in the present invention, an incineration portion 80 (flare stack) is installed at the rear end of the blower 30 to stop the fueling operation of the gas in an emergency and to further improve safety.

The operation of the incinerator is performed when the composition ratio of methane in the LFG to be collected is less than 37%, the engine generator to use the LFG as fuel when the treatment of the surplus gas is required to exceed the capacity that the LFG collection amount can handle; If the LFG is to be processed due to sudden stop of the storage facility, the LFG is collected and incinerated to prevent odor and spontaneous ignition of the landfill, which occurs when the operation (Gaspo) is stopped for the maintenance and repair of the equipment. .

The incinerator should consider the fire resistance to withstand the high temperature (about 1700 ℃) generated during incineration, and a flame arrestor should be installed at the front of the incinerator to prevent flash back during combustion. In addition, it should be possible to interlock according to the condition of the equipment operated such as blower, generator.

In addition, in the present invention, the condensate treatment unit 90 is provided with a drain valve as a pipe for connecting the above components and the condensate (leached water) to be sent to the collection tank for treatment. This is to prevent secondary contamination by condensate and to prevent corrosion of equipment.

The LFG fueled through this configuration can be used in the power generation facility 120, and is distributed to the gas consumer through the gas compressor 91 and the gas mixer 92.

The gas compressor (91) is a low-pressure LFG and supply gas (1.5 ~ 5.5 ㎏ / ㎠G) and to supply as a fuel by mixing the purified LFG after the pre-treatment process with the city gas Compressed to the same pressure and mixed with the city gas through the gas mixer 92 is installed for storage in the storage facility (130). At this time, the type of gas compressor should consider the conditions of use (supply gas quantity and operation conditions).

The gas mixer 92 is installed to mix the LFG and the city gas that are compressed and supplied through the gas compressor 91. The amount of heat (Kcal / Nm3) of methane of the LFG should be measured, and the shortage of the amount of heat of the gas to be supplied is mixed with the city gas and supplied to the storage facility 130.

The present invention configured as described above can effectively collect LFG gas, can improve the safety, which is the most important point of the gasification system, and have the advantage of achieving economical operation.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described.

Rather, it will be apparent to those skilled in the art that many changes and modifications to the present invention are possible without departing from the spirit and scope of the appended claims. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

1 is a schematic configuration diagram of an LFG gas fueling device according to the present invention,

2 is a flow chart showing a fuelization process using the LFG gas fueling apparatus according to the present invention,

3 is a block diagram showing an embodiment to which the LFG gas fueling device according to the present invention is applied,

4 is a configuration diagram showing a detailed configuration of FIG.

<Description of the symbols for the main parts of the drawings>

10: collecting part 20: first gas filter

30: Brower 40: washing tower

50: condensation unit 51: cooling water supply unit

52: bypass unit 60: moisture drying unit

70 second gas filter 80 incineration (flare stack)

90: condensate treatment unit 100: gas compression unit

110: gas mixer 120: power plant

130: storage facility

Claims (5)

In the device for collecting and fueling the LFG gas generated from the landfill, A collecting part installed in the landfill to suck gas; A first gas filter for purifying the gas flowing through the collecting unit; A blower for sucking and discharging gas through the collecting unit installed in the landfill; A washing tower for washing gas introduced through the brower using washing water; A condensation unit for condensing the gas cleaned through the cleaning tower; A moisture drying unit drying the moisture in the gas supplied from the condensation unit; And And a second gas filter for removing harmful compounds in the gas passing through the moisture drying unit. The condensation unit further includes a bypass unit, and when the external temperature is low, the LFG gas fueling apparatus, characterized in that bypassed through the bypass unit without passing through the condensation unit. The method of claim 1, wherein the condensation unit, The LFG gas fueling apparatus further comprises a cooling water supply for supplying and circulating the cooling water. delete The method of claim 1, The LFG gas fueling apparatus further comprises an incinerator for incinerating the gas introduced by the suction of the brower. The washing tower of claim 1, A washing step of washing by spraying washing water continuously; Contacting the LFG with the filler; Collecting and forcibly circulating the washing water used in the washing process and resupplying the washing water; And Measuring the pH concentration of the circulating washing water and circulating the washing water; LFG gas fueling apparatus comprising a.

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