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Heat recovery of compost reactors: field study of operational behaviour, heating power and influence factors

Jaschke Nele, Schmidt-Baum Torsten

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 2

201--217

EN

This study evaluates the common process and set-up design of a static compost bioreactor for heat recovery. A technology, which fits the goal of a sustainable, growing bioeconomy which combines the utilization of compost heat and compost material. Interest on this technology has been growing the last years but precise data of pilot scale reactors is rare. Data is required to adjust the process for custom needs and further technical development. Therefore, lignin-cellulose based biomass was composted in unaerated cylindrical compost reactors size 20 to 70 m3 for 140 days. The biomass comes with C:N ratio of about 25:1, water content of 43-48 %, organic matter content of 40.6 % d.m. and calorific value of 8.3 MJ/kg d.m. Spatial distribution of temperature and gas concentration (oxygen, carbon dioxide, methane) within the reactor shows methane production of the anaerobic core area. Maximum thermal power of 5.2 kW from a 63 m3 reactor with average temperature of heating flow about 40 °C was reached. Maximum recovered heating power of 4.8 MJ/kg d.m. was calculated for an operation of 6 month. This corresponds to 50 % of the measured calorific value. Biggest influence factors detected on the recovered heating power of the pilot scale reactor has been the size of reactor, the set up quality and the control of heat exchanger. The spatial correlation between heat production and aerobic digestion suggests a technical development in terms of aeration.

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First step to urban mining. Restoration of gas wells in municipal waste deposits and reactivation of gas production

Otto F., Kanitz J., Pawelczyk S.

Systemy Wspomagania w Inżynierii Produkcji

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2016

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z. 5 (17)

216--228

PL

W artykule przedstawiono dwa tematy dotyczące studni odgazowania:na składowiskach odpadów komunalnych, które nie dostarczały odpowiedniego dla wykorzystania gazu oraz opuszczonych składowiskach odpadów komunalnych, zamkniętych w latach 80. XX w. Oba rodzaje składowisk stanowią zagrożenie dla środowiska – są źródłem zanieczyszczeń atmosfery, a problemem w obu przypadkach jest brak środków finansowych na przeciwdziałanie tym zagrożeniom. Celem badań zespołu THGA było znalezienie niskonakładowych rozwiązań umożliwiających ograniczenie zanieczyszczeń wokół wspomnianych składowisk odpadów komunalnych.

EN

There are two themescombined: first, there are gas wells in municipal waste deposits with leakages which don’t deliver usable gas anymore and second, there are abandoned municipal waste deposits closed in the 1980’s with any sealing neither at bottom nor on top. Both, abandoned municipal waste deposits and waste deposits with leakages in their gas wells, are sources of air pollution and common to both is the lack of money to stop this pollution. The aim of research team of THGA is to find cheap solutions to stop the contamination around municipal waste deposits. Gas wells in municipal waste deposits normally are filtered from the bottom to the top over their full length. In the top layers the organic waste reacts with oxygen and these parts are inertised in a short time. This will result in leakages between the surface and the well. From that time the well will suck air from the surface but no more gas from deeper layers. Power plants cannot work anymore because of the bad quality of the gas. In a laboratory test the restoration of such wells with a special kind of foam was tested and improved. Later in several wells of Celje municipal waste deposit (Celje, Slovenia) leakages were located in sucking tests. The filter lengths with leakages were foamed and after this restoration gas of higher quality was sucked. In the last century nearly every village in Germany, but not only there, had have their own municipal waste deposit. There was no soil or groundwater protection or a system to suck any gas. By the first “LAGA Merkblatt – Die geordnete Ablagerung von Abfällen” (a regulation about waste deposits in Germany) from September 1979 a system with a new type of landfills started. This type contains a base of low permeability, water and gas drainage system, as well as surface covering. Concentration on a few great landfills began and a lot of old landfills were abandoned. These old landfills were covered with soil and most of them still exist in this form in the landscape. Unfortunately these landfills still show chemical reactions. They still produce waste water and landfill gas. So they are contaminating the groundwater and their gas production still destroysthe vegetation on their surface. Methane and carbon dioxide are polluting the atmosphere. But most authorities don’t accept this problem because these landfills have been closed for more than 30 years, and therefore the landfills are expected to be inert.

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Studium uwarunkowań emisji gazów ze zlikwidowanych kopalń SW części GZW (część V)

Grzybek I.

Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie

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2012

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nr 5

10-18

PL

KWK "Morcinek" udostępniały trzy szyby, m.in. na poziomach: 650, 800 i 950 m. Po likwidacji kopalni, koncentracje CH4 i C02 w szybach wzrosły ze znacznym opóźnieniem, krótszym w szybie III. W szybach I i II ustabilizowały się później na typowym dla każdego z nich poziomie, zbliżonym do ich koncentracji w gazach złożowych udostępnionych szybami stref gazowych. W szybie III zaznaczyło się natomiast zastępowanie metanu przez azot. Późne ujawnienie się emisji tych gazów wynikało z oporów przepływu, których pokonanie możliwe było po zatopieniu części zrobów i wzroście ciśnienia w ich obrębie. Migracja gazów w szybach zachodziła poziomami 650 i 800 m. Główną rolę odgrywał jednak poziom 650 m, z uwagi na wyższy gradient ciśnienia pomiędzy nim a zrębami szybów. Wcześniejsze rozpoczęcie emisji z szybu III wiązało się z rozszczelnieniem jego połączeń ze zrobami (wybuch metanu, ucieczki zasypu), a wzrost koncentracji azotu koresponduje z zatopieniem poziomu 950 m i wynika z wypychania zatłoczonego tam wcześniej azotu.

EN

The deposit of Morcinek mine was developed through three shafts, on the production levels: 650 m, 800 m and 950 m among others. After the liquidation of the mine CH4 and C02 concentrations in the filled up shafts increased (Fig. 22) not before 520 (shaft III) and 890 days (shafts I and II). In shafts I and II, the concentrations stabilized later at a level typical for each of these shafts, similar to constitution of deposit gases within different gassy zones of methane content field. However, in the III shaft became evident the methane replacement by nitrogen (Fig. 24). Such a late manifestation of mine gases emission arises from flow resistance within shafts, which suppression was impossible before flooding of part of mine gobs and rising of the gas pressure within them. The migration of gases took place only from levels 650 m and 800 m. Level 650 m, however, played the main role, because of pressure gradient between the level and the shafts mouths higher then in case of level 800 m. Earlier manifestation of emission in shaft III is connected to dishermetization of its connections to gobs, caused by the methane explosion and the earthquakes. The increase of nitrogen concentration observed in it corresponds to flooding of 950 m level and is the result of extruding the nitrogen crammed before. At the same time, the start of gobs degasation caused the drop of CH4 concentration in all of the shafts, while changes of barometric pressure manifested their influence on gases concentration in the shafts, causing oscillations of the concentrations around the values typical for each particular shaft (Fig. 25).

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Rozkłady powierzchniowe strumienia gazu na ścianach komory kalibracyjnej w układach z dynamiczną ekspansją gazu

Szwemin P., Szymański K.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2002

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z. 143

105-110

EN

The possibilities of systematic uncertainties caused by non-uniform distributions of the gas flux on the calibration chambers walls of the standards with the dynamic expansion of gases were investigated in this work. The Monte Carlo method was used to study the gas flux distribution as well as the correction factors where the calibrated gauges are located. It was found that at the half of of the chamber height the gas flux density is equal to that computed as a mean value existing inside the chamber. Unproper gauge location may cause the relative systematic deviation of the generated pressure as high as the relative orifice area, which is significant. The results are valid also for relatively large orifices openings what enables decreasing the lower limit of generated number density.