where Q_H2 is the volumetric hydrogen flow produced by the
plant, m_ bio;daf is themass flow rate of biomass dry and ash free
feeding the plant and HV is the Heating Value (High or Low) of
hydrogen and dry ash free biomass, respectively.
As mentioned above, biomass feedstock and its moisture
content are fixed, so steam flow rate has been changed according
to the value considered for the steam to biomass ratio
(S/B). Under these conditions, the simulations show how the
results depend on this ratio and on the gasification temperature.
Fig. 3 shows that the hydrogen energy ratio (HER) of the
gasifier at each gasification temperature level first increases
and then decreases when S/B is increased. This trend is clearly
shown on the Figure at 750 and 800 C and it is probably present
also at 850 C although the maximum would appear in
this case for higher steam to biomass ratio. At 750 C and
800 C the maximum HER of the gasifier corresponds to S/B ¼ 1.5 (37.5% and 41.0%, respectively). As it is known from the
literature [48e50], the hydrogen yield increases with the
gasification temperature and with the steam to biomass ratio.
The gas yield calculated at T ¼ 800 C and S/B ¼ 1.5 is 1.3 Nm3/
kg.
The catalytic filter candles (Fig. 4) improve the HER. This is
because methane steam reforming, tar steam reforming and
water gas shift reactions occur inside the candles [36]. The
steam reforming reactions are enhanced at high temperature,
whereas the water gas shift thermodynamic equilibrium is
more favourable at low temperature.
Therefore, as shown in Table 2, gas quality and gas yield
(1.9 Nm3/kg) increase. Increasing the steam to biomass ratio
reduces the methane concentration and also the temperature
at the candle outlet, because endothermic reforming reactions
occur inside the candles. However, the carbon monoxide
concentration increases less than proportionally to the
methane reacted: this behaviour is expected, because inside
the candles the water gas shift reaction also occurs, which is
enhanced at low temperature, whereas methane is preferentially
reformed when the operating temperature is increased.
Tar concentrations are predicted to be negligible in the candles
output.
where Q_H2 is the volumetric hydrogen flow produced by theplant, m_ bio;daf is themass flow rate of biomass dry and ash freefeeding the plant and HV is the Heating Value (High or Low) ofhydrogen and dry ash free biomass, respectively.As mentioned above, biomass feedstock and its moisturecontent are fixed, so steam flow rate has been changed accordingto the value considered for the steam to biomass ratio(S/B). Under these conditions, the simulations show how theresults depend on this ratio and on the gasification temperature.Fig. 3 shows that the hydrogen energy ratio (HER) of thegasifier at each gasification temperature level first increasesand then decreases when S/B is increased. This trend is clearlyshown on the Figure at 750 and 800 C and it is probably presentalso at 850 C although the maximum would appear inthis case for higher steam to biomass ratio. At 750 C and800 C the maximum HER of the gasifier corresponds to S/B ¼ 1.5 (37.5% and 41.0%, respectively). As it is known from theliterature [48e50], the hydrogen yield increases with thegasification temperature and with the steam to biomass ratio.The gas yield calculated at T ¼ 800 C and S/B ¼ 1.5 is 1.3 Nm3/kg.The catalytic filter candles (Fig. 4) improve the HER. This isbecause methane steam reforming, tar steam reforming andwater gas shift reactions occur inside the candles [36]. Thesteam reforming reactions are enhanced at high temperature,ในขณะที่ก๊าซน้ำกะทางอุณหพลศาสตร์ สมดุลคือดีมากที่อุณหภูมิต่ำดังนั้น ดังแสดงในตารางที่ 2 ก๊าซและก๊าซคุณภาพผลผลิต(1.9 Nm3 กิโลกรัม) เพิ่มขึ้น เพิ่มไอน้ำอัตราส่วนชีวมวลช่วยลดความเข้มข้นของมีเทน และอุณหภูมิที่ปลั๊กเทียน เนื่องจากปฏิรูปปฏิกิริยาดูดความร้อนเกิดขึ้นภายในเทียน อย่างไรก็ตาม คาร์บอนมอนอกไซด์เพิ่มความเข้มข้นที่น้อยกว่าตามสัดส่วนปฏิกิริยามีเทน: พฤติกรรมนี้คาดว่า เนื่องจากภายในเทียนน้ำก๊าซกะปฏิกิริยาเกิดขึ้น ซึ่งเป็นเพิ่มขึ้นที่อุณหภูมิต่ำ มีเทนเป็นพิเศษขึ้นเมื่ออุณหภูมิการทำงานจะเพิ่มขึ้นความเข้มข้นของน้ำมันคาดว่า จะเป็นเล็กน้อยในเทียนผลผลิต
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