Design of a pilot post-combustion CO2 capture by calcium looping using industrial limestone waste
In process to find the suitable technology, Many aspects need to be considered in the first place to determine the feasibility and limitations of any design project. These aspects are the project’s constraints and include, but are not limited to, economic, environmental, manufacturability, functional, safety, social, political, and time constraints.
. Understanding design constraints is especially crucial since, without limits and constraints, everything is possible; however, in the real world, that is not true. Eventually, it is essential to establish limits and work within them to prevent any future problems.
Economic Constraints:
One of the most critical constraints that must include is the economic constraints of the project.
Most of the initial costs will be from the machinery and other capital costs.
It is also essential to consider the economic constraints regarding manufacturing, distribution, design, and resources. However, since we are utilizing the university’s design software, design costs are insignificant in our project.
Functional constraints:
In our project, there are some functional constraints. Firstly, we need to 1-minimize the energy consumption as it will help to reduce the costs which ensure sufficient energy for the capturing . There are other functional constraints that needs to be used or some problems and leakage will happen. These constraints include 2-the flow and transport of the materials. The key limitation would be the size of the plant, having the plant near the EGA’s is essential to assure that will directly transport with the highest heat amount. Furthermore, storage tanks should be kept in a safe way.
If the purity does not reach industry standards major losses will occur as the product could be sell for really cheap price or not sell at all. therefore, there is a need for a strict quality control to be placed to ensure high purity level.
Moving to another functional constraint which is 3-the location, as there is a requirement of a huge open area for the calcium looping.
Environmental Constraints:
In order to design a project, it is important to take the environmental impact and sustainability aspects in consideration. Since our process involves capturing the emissions. We can easily identify that there will be the positive environmental impact instead of negative. The only environmental impact that might happen would be if any gas leak or explosion accrues; hence, it is important to have improved monitoring and safety devices to avoid any leaks and explosions from happening. Regarding sustainability, since we are using the industrial waste as a source of CaO, our process is highly sustainable
Safety Constraints:
In process to achieve the ethical code the project must be safe and not affect any health and safety and no present of hazards. In our project, we deal with gasses and they are not toxic unless present in high concentrations which will affect the environment if a leak occurs. So as stated before, the best way to prevent the leak is monitoring, advanced devices and safety measure should be placed to reduce the risk.
These constraints have been ranked in order of their importance and given a weighted score as summarized in this table.
| Table 1. Decision matrix constraints | ||||||
| Safety | Functionality | Manufacturing | Environment | Cost | Total | |
| Safety | – | 1 | 1 | 1 | 1 | 4 |
| Functionality | 1 | – | 1 | – | 1 | 3 |
| Manufacturing | – | 1 | – | – | 1 | 2 |
| Environment | 1 | – | – | – | – | 1 |
| Cost | – | – | 1 | – | – | 1 |
*It was concluded that safety followed by functionality are the main constraints that must be considered, followed by manufacturing and environmental friendliness, while the cost is the least factor to be considered.*
Four separation techniques have been chosen for comparison to finally decide on the technology that meets the specification requirements. Where the technologies are (1,2,3,4)
| Weight | 1-Steam hydration technology | 2-Cascade cyclones technology | 3-Calcium looping technology | 4-Microbial or Algae system | |
| Safety | 4 | 4 x 100 = 400 | 4 x 75= 300 | 4 x 100 = 400 | 4 x 50 = 200 |
| Functionality | 3 | 3 x 50 = 150 | 3 x 25= 75 | 3 x 50 = 150 | 3 x 25 = 75 |
| Manufacturing | 2 | 2 x 50 = 100 | 2 x 25 =50 | 2 x 50 = 100 | 2 x 50 = 100 |
| Environment | 1 | 1 x 50 = 50 | 1 x 50= 50 | 1 x 100 = 150 | 1 x 75 = 75 |
| Cost | 1 | 1 x 50 = 50 | 1 x 50 = 50 | 1 x 50 = 50 | 1 x 50 = 50 |
| Total | 750 | 525 | 850 | 500 |
This table presents the comparison of four different technologies to capture based on safety, functionality, ease of manufacturing, the effect on the environment, and cost. From the analysis in table 3 above, the stream hydration and calcium looping technologies had the highest safety and functionality score, which are the two main constraints. Also, they scored 100 points in the manufacturing factor, same as the Microbial or algae system, while the cascade cyclones scored only 50 points. Additionally, the calcium looping technology had the highest environmental factor score because it produces zero carbon dioxide emissions. Furthermore, the 4 technologies had the same score, 50 points, in cost constraint, which means that all technologies are economical. As a result of analyzing the data, we conclude that the capture of through Calcium looping technology has emerged as the best alternative and will be explored further in this project.
