*Application of the Six Sigma DMAIC Methodology to the Gasification Process DOI: http://dx.doi.org/10.5772/intechopen.111850*


*Application of the Six Sigma DMAIC Methodology to the Gasification Process DOI: http://dx.doi.org/10.5772/intechopen.111850*

**Figure 12.** *Serpentine.*

(2) Furthermore, the cooling water flow can be controlled by a control valve (CV) linked to a Temperature Indicator Transmitter (TIT) to partially open or close the CV. Furthermore, a Flow Indicator Transmitter (FIT) can indicate the actual cooling water flow. **Figure 13** depicts the control system.

**Figure 13.** *Temperature control system.*

*Airflow system:* The airflow is controlled by partially opening or closing a valve based on the flowmeter indication. Therefore, an error is added to the flow ratio since an operator performs the opening and closing of the valve, so the precision depends on how well an operator's eyesight is. The proposed solutions are: (1) Automate the airflow system through a control valve and two flow indicator transmitters. The control system aims to link the air's FIT with the biomass FIT, so the control valve will open or close to allow an airflow based on the amount of fed biomass and the established ER. **Figure 14** depicts the control system.

**Figure 14.** *Air flow control system.*

**Figure 15.** *PLC gasification process.*

*Application of the Six Sigma DMAIC Methodology to the Gasification Process DOI: http://dx.doi.org/10.5772/intechopen.111850*

*Biomass flow system:* Several previous actions are necessary to control biomass flow, such as pretreating the biomass by establishing a homogeneous particle diameter range. This consideration is essential so that the feeder screw feeds the biomass homogeneously. (2) Another option is to change the mechanical feeding system to a pneumatic one, requiring biomass pretreatment and screening.

#### **4.5 Control**

The control phase sustains the Six Sigma DMAIC initiative through continuous monitoring to avoid the same problem [48]. So, a PLC can be installed to monitor and control the process as described in the improvement section. The PLC allows the operator to interact with the process without opening or closing valves to a particular flow, adding errors to the process. Furthermore, the PLC can save data by analyzing the process and promoting continuous improvement. **Figure 15** shows a typical PLC interface adapted to the gasification process.

## **5. Conclusion**

In this chapter, the Six Sigma DMAIC methodology is used to identify causes of variance in the gasification process and suggest opportunities for improvement. In terms of the Equivalence Ratio (ER), the developed Failure Modes and Effects Analysis (FMEA) has a high-Risk Priority Number (RPN). This high figure is due to the method of feeding biomass, which significantly impacts airflow. In addition, the temperature has a high RPN value as well. This situation is due to the cooling mechanism of this device and the ER employed, which may be inaccurate. Finally, some ways are proposed to improve the air and biomass feeding and process cooling systems.

On the other hand, it demonstrated the process's stability and the synergy between RDF and biomass, resulting in enhanced gasification products. Furthermore, no slag, agglomeration, or defluidization phenomena were observed. Again, implementing the DMAIC methodology helped identify the source of variance and ways to enhance the overall process. Therefore, it has the potential to strengthen the gasification process, promoting the economic viability and environmental benefits of future and existing gasification plants.
