🔧 Detailed Design Calculations: Plastic to Fuel Pyrolysis Plant (10 TPD)

 

1. Input Data and Assumptions

Parameter	Value	Unit
Plant capacity	10,000	kg/day
Operation time	20	hours/day
Bulk density of plastic flakes	0.25	kg/L
Plastic to oil yield (avg.)	70	%
Heating value of feedstock	35	MJ/kg
Specific heat of plastic	2.0	kJ/kg·K
Target pyrolysis temp.	450	°C
Ambient temp.	30	°C

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2. Material Balance

Daily Feedstock:

• 10,000 kg plastic/day

Estimated Product Yields:

• Oil: 70% → 7,000 kg/day

• Gas: 20% → 2,000 kg/day

• Char: 10% → 1,000 kg/day

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3. Energy Requirement for Pyrolysis

Heating Load (Q):

$$Q = m \cdot c \cdot \Delta T$$

• $m = 10,000$ kg/day

• $c = 2.0$ kJ/kg·K

• $\Delta T = 450 - 30 = 420$ °C

$$Q = 10,000 \cdot 2.0 \cdot 420 = 8,400,000 \text{ kJ/day}$$

Convert to kWh:

$$8,400,000 \div 3600 = 2,333 \text{ kWh/day}$$

Add heat losses (assume 25%):

$$Q_{\text{total}} = 2,333 \cdot 1.25 = 2,916 \text{ kWh/day}$$

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4. Reactor Sizing

Assume 4 hours residence time and 250 kg/h feeding rate

$$\text{Volume} = \frac{\text{Mass}}{\text{Density}} = \frac{1,000}{250} = 4.0 \text{ m}^3$$

Assuming horizontal cylindrical reactor:

$$\text{Volume} = \pi \cdot \frac{D^2}{4} \cdot L$$

Assume L = 4 m:

$$4 = \pi \cdot \frac{D^2}{4} \cdot 4 \Rightarrow D = 1.13 \text{ m}$$

=> Reactor Size: 4 m length x 1.13 m diameter

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5. Condenser Sizing

Condense 7,000 kg/day of vapor to liquid

• Vapor flow rate: 350 kg/h

• Latent heat of condensation: 300 kJ/kg

• Cooling water ΔT: 10°C

$$Q = m \cdot L = 350 \cdot 300 = 105,000 \text{ kJ/h}$$

Cooling water flow rate:

$$Q = m \cdot c \cdot \Delta T \Rightarrow m = \frac{105,000}{4.18 \cdot 10} = 2,510 \text{ kg/h} \approx 2.5 \text{ m}^3/h$$

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6. Gas Scrubber and Flare Sizing

Combustible Gas: 2,000 kg/day (~100 kg/h)

Assume methane equivalent:

$$\text{Energy value} = 50 MJ/kg \Rightarrow 5,000 MJ/day = 1,389 kWh/day$$

Flare size estimation:

Assume 10 kg/h continuous flaring

Use flame diameter ≈ 0.3–0.5 m with vertical pipe height ≈ 3 m

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7. Fuel Oil Storage

Yield = 7,000 kg/day, assume density = 0.85 kg/L

$$\text{Volume} = \frac{7000}{0.85} = 8,235 \text{ L/day}$$

For 3 days buffer:
Storage Tank = 25,000 L (use 30,000 L for contingency)

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8. Char and Ash Handling

Char output = 1,000 kg/day
Assume stored in 1-ton jumbo bags or silos

Silo size (1.2 bulk density):

$$\text{Volume} = \frac{1,000}{1.2} = 0.83 \text{ m}^3/day$$

Use 3–5 m³ silo for buffer capacity.

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9. Electrical Power Consumption (Estimation)

Equipment	Power (kW)	Duration (hr)	Energy (kWh)
Reactor Heater	100	20	2,000
Condenser Pumps	5	20	100
Feed System	2	20	40
Scrubber/Fan	3	20	60
Automation + Lighting	5	24	120
Total Daily			2,320 kWh

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✅ Summary Table

Item	Design Value
Reactor Volume	4 m³
Reactor Dimensions	Ø1.13 m × 4 m
Energy Required	2,916 kWh/day
Condenser Water Flow	2.5 m³/h
Daily Oil Output	7,000 kg
Storage Tank Size	30 m³
Total Electric Consumption	~2,320 kWh/day

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