Bir atık kağıt geri kazanım tesisinde sera gazı emisyon azaltım alternatifleri
Alternatives for reduction of greenhouse gas emission  in a paper recycling plant
Yazar: MERVE KÜBRA TÜTER
Danışman: PROF. DR. KADİR ALP
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri, Mühendisliği ve Yönetimi Bilim Dalı
Derece: Yüksek Lisans, 2019
Konu: Çevre Mühendisliği = Environmental Engineering

Özet:
Sera gazları, yeryüzü sıcaklığı üzerinde doğrudan etkisi olan ve küresel ısınmaya yol açan atmosferik bileşenlerdir. Fosil yakıtların kullanılması ile atmosferdeki sera gazı miktarı her geçen gün artış göstermektedir. Günümüzde fosil yakıtların artan enerji ihtiyacını karşılamada yetersiz olması ve bu yakıtların tüketiminin iklim değişikliğine sebep olmasından dolayı alternatif enerji kaynakları için yeni teknolojiler geliştirilmektedir.
Kağıt sektörü, global sera gazı emisyonlarının %1'ine denk gelen, en düşük sera gazı emisyonuna sebep olan sektördür. Ancak son yıllarda kağıt ürünlerine ait talebin artışı, sektörde üretim miktarlarının da artmasına sebep olmuştur. Bu durum; daha fazla üretimi teşvik ederken aynı zamanda çevresel tahribata yol açmaktadır. Yalnızca orman tahribatı değil aynı zamanda su kaynaklarında olduğu kadar endüstriyel kimyasalları yapmak için kullanılan hammaddelerin ve gerekli katkı maddelerinin de daha fazla kaynak imhasına ilişkin tehlikeleri arttırmaktadır. Doğal kaynak kullanımına önemli katkısı olan geri dönüştürülmüş kağıtların üretimde daha fazla kullanılması; hem enerji tasarrufu hem de ekonomiye katma değer sağlamaktadır.
Günümüzde faydalanılabilir enerji kaynaklarının kısıtlı olması, teknolojik gelişmelere bağlı olarak artan enerji talebi ihtiyacını karşılamada yetersiz olması ve fosil yakıtların tüketiminden kaynaklı iklim değişikliği gibi çevresel sorunlardan dolayı alternatif enerji kaynakları için yeni teknolojiler geliştirilmektedir. Yenilebilir enerji kaynakları arasında yer alan biyokütle; çevreye katkısı, maaliyetinin düşük oluşu, erişim kolaylığı vs. avantajlarından dolayı önemli bir kaynaktır. 
Bu tezde; çevreye oldukça önemli katkısı olan bir atık kağıt geri dönüşüm tesisinin tükettiği fosil yakıtlardan kaynaklı sera gazı emisyonlarının miktarının belirlenmesi, tesisin mevcut üretim hattında iyileştirme olanaklarının araştırılarak, sera gazı emisyon azaltımına yönelik alternatiflerinin değerlendirilmesi gerçekleştirilmiştir.
Bu tezde; kağıt sektöründen kaynaklanan sera gazı emisyonları özelinde geri dönüşüm kağıtlarının kullanıldığı bir prosesten oluşan atıkların enerjisinden yararlanılması durumunda ne mertebede azaltılabileceğine yönelik teorik bir değerlendirme yapılmıştır. Tesisin üretiminden kaynaklanan reject atıkların kalorifik değeri yüksek olduğu görülmüş olup bu çalışmada bu atıklardan piroliz ve gazlaştırma yöntemleri ile enerji elde edilmesi amaçlanmıştır. Reject atıklardan elde edilen bu enerjinin tesiste tüketilen yakıt miktarının azalmasına sebep olarak tesisin hesaplanmıştır. Yapılan değerlendirmeler sonucunda referans senaryoya kıyasla gazlaştırma yönteminin uygulanması %23 oranında emisyon azaltımına sebep olurken, piroliz yönteminin uygulanması ise %19 oranında azaltıma sebep olmaktadır.

Abstract:
Greenhouse gases are atmospheric components that have a direct impact on the earth's temperature and cause global warming. The amount of greenhouse gas in the atmosphere increases with the use of fossil fuels. Nowadays, new technologies are being developed for alternative energy sources because of the inadequacy of fossil fuels to meet the increasing energy needs and the consumption of these fuels cause climate change.
The paper sector, which accounts for 1% of global greenhouse gas environments, is the sector with the lowest greenhouse gas emissions emitters. However, the increase in demand for end-product diversity has led to an increase in production volumes in the sector. This situation; while encouraging further production, it also leads to environmental destruction. Not only forest destruction but also water resources as well as the raw materials used to make industrial chemicals and the necessary additives increase the hazards associated with further resource destruction. Greater use of recycled paper in production, which makes a significant contribution to the use of natural resources; It provides both energy saving and added value to the economy.
Today, new technologies are being developed for alternative energy sources due to the limited availability of available energy sources, insufficient capacity to meet the increasing energy demand due to technological developments, and environmental problems such as climate change due to the consumption of fossil fuels. Among the renewable energy sources, biomass; is an important resource because of its advantages like contribution to the environment, low cost, ease of access etc.
In this thesis; In order to determine the amount of greenhouse gas emissions from fossil fuels consumed by the waste paper recycling plant in Istanbul which has a significant contribution to the environment, and to investigate the improvement possibilities in the existing production line of the facility, the alternatives for greenhouse gas emission reduction have been evaluated.
In addition, the current situation of the plant has been determined by comparing the best technology indicators applied all over the world for improvement areas.
In this thesis; A theoretical assessment was made on the extent to which greenhouse gas emissions from the paper industry can be reduced, in particular if the energy of wastes from a recycling process is utilized.
Greenhouse gas reduction potentials were evaluated in different scenarios. These scenarios are below;
Scenario 1: Syngas production by gasification of reject wastes
Scenario 2: Diesel production by pyrolysis of reject wastes
Scenario 3: It was determined as cooling and condensing and using the water vapor coming out of the drying chimney.
Reference scenario is current situation of selected paper recycling plant. In reference scenario it is calculated the total green house gases emissions from fossil fuels consumptions, disposal and transportation of rejects. The total greenhouse gases emissions are calculated as 99.219 tons CO2e /per year.
Wastes occur during the production phase of the facility are called "reject". Rejected wastes mainly consist of plastic, textile materials, glass, stone, gravel, sand and metals. These wastes are stored separately and sent to the energy facility for disposal. In this thesis; instead of reject incineration, it is aimed to gain energy from rejects which have about 6000 kcal dry calorific value.
The amount of rejects in the facility (15-20%) was found to be well above the rate seen in the best practices (4-10%). Thanks to research done in this case the plant is not in the special paper is understood to have taken place in Turkey a problem of recycling facilities. The low quality of domestic paper compared to imported paper, and the high amount of these reagents contained in the waste paper lead to both loss of labor for sorting and serious economic costs.
It is seen that reject wastes arising from the production of the plant have high calorific value and in this study it is aimed to obtain energy from these wastes by pyrolysis and gasification methods. Reject was calculated as the energy obtained from the wastes decreased the amount of fuel consumed in the plant. 
In Scenario 1 based on the gasification process, natural gas consumption decreases up to 5,322 tons/year with the steam obtained from syngas and the natural gas activity data decreases from 15,583.87 tons/year to 10,261 tons/year. In addition, when lignite savings of 6,470 tons/year were accepted by using tar as an alternative in the fluidized bed boiler, the annual lignite consumption value decreased from 21.496,90 tons/year to 15,027 tons/year, and as stated in the reference scenario, 243 tons of transported waste from the plant to energy facilities It has been calculated that greenhouse gas emissions are reduced as CO2/year emissions are made within the site of the direct disposal plant.
In Scenario 2 based on pyrolysis process, it is calculated that natural gas consumption decreased by 5.960 tons/year with the electricity production obtained by diesel engine. In this case, the natural gas activity data decreased from 15.583,87 tons/year to 9.623 tons/year, the total greenhouse gas emissions of the plant decreased to 80.203 tons CO2/year and a total saving of 19.017 tons/year was achieved.
Total greenhouse gas emissions from Scenario 1 are calculated as 76.242 tons CO2/year and it is possible to save 22.977 tons/year CO2 compared to the reference scenario. It is calculated that the total amount of greenhouse gas emissions arising from Scenario 2 is 80.202 tons CO2/year and a total saving of 19.017 tons/year CO2 is saved compared to the reference scenario.
As a result of the evaluations, the gasification method reduces the emissions by 23% compared to the reference scenario, while the pyrolysis method reduces the emissions by 19%.
When focusing on Scenario 3; the temperature and humidity rate of the gas released to the atmosphere in the drying chimneys were investigated. The flue gas outlet temperatures are 50 °C, which is well below the recoverable amount. Therefore, no alternative alternative to focused energy efficiency could be found.
However, the design of the facility needs to be redesigned considering the seasonal variation of the objective analysis. The composition of the syngas obtained by the gasification process should be tested in the laboratory and feasibility studies are recommended in this direction. Conducting studies on costs will allow for more realistic choices.