Good day everyone, this post is under construction since 2 months, and posting today.
This post wont contain any major calculations part but just a theory section which might help in extend thinking.
Usually the company which achieves higher deliverable's and same time meeting the quality stands at top. Here quality stands for not only product purity but also w.r.t. manufacturing style i.e., zero data integrity issues. Quality means performing / doing something in a proper way even when nobody sights you.
Getting into the topic, Capacity enhancement is a regular term which is used by many guys to achieve higher tonnage of products. Usually capacity enhancement can be achieved through,
1. De-bottle necking the current process w.r.t. equipment & process,
2. Scaling up of process (enhancing the batch size),
3. Greenfield projects / Increasing the streams,
4. Outsourcing.
4. Outsourcing.
Out of the above three, de-bottle necking is the simple way when there is a accurate strategy, else we have to go for scaling up, if not then create a greenfield projects.
I. De-Bottle necking:
De-bottle necking involves finding the bottle necks in the process and eliminating them.
a) Bottle neck elimination through time-cycle optimization by modifying process:
Let me explain you briefly, Lets suppose a process involves three reactors, PNF and a cone dryer. The first reactor is having a reaction and the second reactor is having workups and the third reactor is having isolation and the isolated mass is filtered in PNF and the wet material obtained undergoes drying in cone dryer. Presenting below the relevant time-cycles of the equipment and operations:
Batch Size (Kgs) | Output (Kgs) | Equipment | Time cycle (Hrs) | Batches /day | Tonnage (Kgs/month) |
10 | 15 | Reactor - 1 | 10 | 2.4 | 1080 |
Reactor - 2 | 12 | 2 | 900 | ||
Reactor - 3 | 15 | 1.6 | 720 | ||
PNF | 12 | 2 | 900 | ||
Cone dryer | 12 | 2 | 900 |
Time-cycle is the variable input that i've considered,
Batches / day = 24 / time-cycle; 24 is hours/day
Tonnage / month = 30 x batch output x Batches/day;
30 is manufacturing days/month, some fellas may consider as 26.
From the above tabulation, if we can observe keenly the bottleneck is Reactor-3 which requires 15 hours of time-cycle and the output that is expected with this type of setup is 720 Kgs/month.
If we are able to reduce the time-cycle of Reactor-3 to 12 hours, the tonnage would be 900 Kgs/month. with a simple act the productivity will increase by 180 Kgs/month and 2160 Kgs/annum.
Also Read:
Vent size calculation for pressure vessels
Evaluation of Filtration in ANFD
b) Bottle neck elimination through an alternate equipment
Sometimes the equipment might become a bottleneck. Lets say there is a filtration operation where ML's expulsion in ANFD requires 20 hours and in centrifuge it requires 15 hours. Then we have to opt for centrifuge to knock out the bottleneck.
** Usually these days many of the companies wont recommend centrifuges, but just as an example i've given the above. Pl don't mind.
c) Bottle neck elimination through adding an additional equipment / stream
As if the equipment used for isolation i.e., Reactor-3 is a bottleneck, an additional reactor can be used for the same purpose and the batch charging frequency can be increased. Below is the tonnage tabulation by incorporating an additional equipment:
Batch Size (Kgs) | Output (Kgs) | Equipment | Time cycle(Hrs) | Equipment no. | Batches / day | Tonnage / month |
10 | 15 | Reactor - 1 | 10 | 1 | 2.4 | 1080 |
Reactor - 2 | 12 | 1 | 2 | 900 | ||
Reactor - 3 | 15 | 2 | 3.2 | 1440 | ||
PNF | 12 | 1 | 2 | 900 | ||
Cone dryer | 12 | 1 | 2 | 900 |
Batches/day = 24/(Time-cycle x no. of equipment's)
Now the tonnage is increased to 900 Kgs / month from 720 Kgs/month.
II. Scaling up the batch size:
This is what usually everyone will think about and there wont be any strain on brain if we select this, because if there is no scope in de-bottle necking then it will be a time waste thing to work on it and if we are able to judge the poor feasibility of de-bottle necking at an early stage then we can use that moment in scale-up detailing.
Usually during scale-up we only thing about facility, but we have to consider both the facility as well as the process(Parameters and RM quantities).
Also Read:
[How To] Design a Scrubber ?
Batch Size selection feasibility
The batch size shall be scaled up or increased based on the volume ratio i.e., either we have to conduct a smaller batch size in pilot plant to check the feasibility and then the batch shall be enhanced.
Refer this post : Batch size selection and feasibility check
The reason why i'm preferring Power per unti volume as a scale-up factor is it will be something like a virtual quantity and can be considered as a dynamic way.
Then we should evaluate each and every operation of the process by breaking those into nodes, like whether the solvent used in the particular operation meets the process requirement during scale-up or not, if not we have to enhance / reduce the quantities. For example, we are performing a filtration and as per the existing process the solids to liquid were in 1:1 ratio i.e., 50% and the mass will be completely heterogeneous which will trigger an issue during feeding operation and the feeding would be inadequate, to resolve these kind kind of issues we have perform some negative experiments like increasing the liquid quantity and checking the impact on yield and quality if not then the quantity shall be enhanced, so that the solids to liquid ration can be made as desirable and the filtration would become good.
Sometimes the washing quantities i.e., as per the lab operations the washing quantities would be effective as they would be handling in buckner filters, whereas coming to plant scale if equipemnt's like ANFD is selected, there would be a problem with the bottom dishes as the bottom dish would accumulate huge volumes and the volumes which are in low proportions would become inadequate in plant scale.
This might be out of topic, but i'll try to explain you with a practical example, we have to filter a reaction mass containing 10 Kgs of material with 0.8 Kg/L bulk density and the solvent quantity be 12 L, the ratio is around 5:6(w/v ratio).
In this scenario, if the same experiment is lab there wont be any quantity in the lab reactors, but if the same is scaled up to plant then the filtration feeding would be terrible as due to the higher solids concentration the feed line may choke and if we go practically there would be some cases like where feed consists of only liquid and the solids would be retained inside the reactor and getting sticked to the walls. These seems to be minor but will become a problem. And during some of the cost improvement projects, the R&D people would optimize the quantity to maximize the improvement projection but leads to problems in plant cases.
And coming to the next step the washing step, where the proposed quantity for washing would be 4 L. And let the proposed equipment is ANFD, the given 4 L would get settled in the bottom of dish and becomes inadequate. These kind of things to be taken care during scale-up evaluation.
Note: I have given only two minor cases, but remember there will be many more involved in the process, which can be addressed only during step by step evaluation.
III. Green Field Projects / Increasing of Streams
Also Read:
Guidelines for process development
Filters Selectivity
III. Green Field Projects / Increasing of Streams
a. Green Field Projects
Most of the engineers these days won't be aware of green field projects as industries now-a-days were interested in optimum usage of resources and encouraging the green field projects will have a higher lead time. But as per me Green field projects were heaven, why because the majority of the equipment's shall be selected based on requirement and not based on availability. Working on these kind of projects will help us gain knowledge and sometimes will help in unleashing the true engineer in us.
Working or developing a green field project is like a back work, usually we will be calculating the capacity based on the available facility and batch size. But in this case based on the requirement we have to select an optimum batch size which can deliver the required tonnage and then we have to perform the volume calculation. Based on the minimum volume and maximum volumes we will be proceeding for equipment selection.
And the thing is majority of the times we will try to scale-up within the available facility and just because of this the original flavour of scale-up is not seen everywhere. But if its a completely new facility we might retain / add that while performing a scale-up. Let me explain you clearly, whenever you read my posts related to scale-up, i'll consider only single parameter(like shaft speed / tip speed / reynolds number / power per volume) for scale-up but not morethan one. Thats because of only one reason that i've considered only single parameter over there and the facility is available.
But getting back to the basics from where we complete our graduation, Scale-up shall be done based on three similarities,
1. Geometrical similarity,
2. Kinematic similarity,
3. Dynamic similarity.
Geometrical similarity: This indicates that both the small scale and large scale equipment's should possess similar ratio's w.r.t. dimensions i.e., Length to Dia & Vessel Dia to impeller dia rations. In case if its a crystallisation reactor we have to be much more careful that the bottom clearence also should be given much importance as any agglomerates if settled at the bottom will lead to solvent entrappment and variation in bulk particle size distribution. Hence below to be taken care:
a. Length to Dia of reactor Ration,
b. Vessel dia to impeller dia ration,
c. Bottom clearence to reactor Dia ration,
d. Gap between the agitators(if its multiple stages),
e. Baffles width and clearence between the baffle-reactor surface.
Geometrical similarity is a must thing for scale-up while evaluating / proposing for a new facility.
Kinematic similarity: This indicates the similarity of velocities, like tip speed, shaft speeds etc. The tip speed of the agitator should be made equal by adjusting the agitator RPM to equal the tip speed of small scale. You all must be aware of the formula for tip speed, but i'll mention it again here: Tips speed = 𝝅 x d x N / 60; Units will be RPS(Rotations per Second).
Dynamic Similarity: This indicates the similarity of forces, like inertial forces, viscous forces etc. Reynolds number, Froude number are useful in maintaining the similarity.
Reynolds number is the ratio of inertial force to Viscous force; Froude number is the ratio of inertial force to gravitational force.
The other thing we should take care is establishing the utilities. The established utilities should have a atleast 50-60% higher than that of required which should suffice in case of further expansion too.
b. Increasing the streams
And the thing is majority of the times we will try to scale-up within the available facility and just because of this the original flavour of scale-up is not seen everywhere. But if its a completely new facility we might retain / add that while performing a scale-up. Let me explain you clearly, whenever you read my posts related to scale-up, i'll consider only single parameter(like shaft speed / tip speed / reynolds number / power per volume) for scale-up but not morethan one. Thats because of only one reason that i've considered only single parameter over there and the facility is available.
But getting back to the basics from where we complete our graduation, Scale-up shall be done based on three similarities,
1. Geometrical similarity,
2. Kinematic similarity,
3. Dynamic similarity.
Geometrical similarity: This indicates that both the small scale and large scale equipment's should possess similar ratio's w.r.t. dimensions i.e., Length to Dia & Vessel Dia to impeller dia rations. In case if its a crystallisation reactor we have to be much more careful that the bottom clearence also should be given much importance as any agglomerates if settled at the bottom will lead to solvent entrappment and variation in bulk particle size distribution. Hence below to be taken care:
a. Length to Dia of reactor Ration,
b. Vessel dia to impeller dia ration,
c. Bottom clearence to reactor Dia ration,
d. Gap between the agitators(if its multiple stages),
e. Baffles width and clearence between the baffle-reactor surface.
Geometrical similarity is a must thing for scale-up while evaluating / proposing for a new facility.
Kinematic similarity: This indicates the similarity of velocities, like tip speed, shaft speeds etc. The tip speed of the agitator should be made equal by adjusting the agitator RPM to equal the tip speed of small scale. You all must be aware of the formula for tip speed, but i'll mention it again here: Tips speed = 𝝅 x d x N / 60; Units will be RPS(Rotations per Second).
Dynamic Similarity: This indicates the similarity of forces, like inertial forces, viscous forces etc. Reynolds number, Froude number are useful in maintaining the similarity.
Reynolds number is the ratio of inertial force to Viscous force; Froude number is the ratio of inertial force to gravitational force.
The other thing we should take care is establishing the utilities. The established utilities should have a atleast 50-60% higher than that of required which should suffice in case of further expansion too.
b. Increasing the streams
Increasing the streams will end up giving fruitful results but it is something like increasing input and getting required output / tonnage. Stream in the sense it refers to similar set of equipment's with similar batch size and getting similar outputs.
IV. Outsourcing Projects
This is a big deal, by tying up with other industries / plants and manufacturing to meet the requirement. Usually when we are not having required resources for meeting the requirements then we have to find an alternate. Out of all the available alternates, the most preferable thing is outsourcing. As in this case we'll need to provide the investment in form of money to hire a facility from other industry and the hired site will do the needful for us.
And this can be considered as a site transfer project and apart from money the parent site need to transfer the manufacturing process, analytical methods, safety studies etc etc. The profit which can be generated from this might be low but when compared to nothing, something is good and above all these we are able to fulfill the customer requirement.
IV. Outsourcing Projects
This is a big deal, by tying up with other industries / plants and manufacturing to meet the requirement. Usually when we are not having required resources for meeting the requirements then we have to find an alternate. Out of all the available alternates, the most preferable thing is outsourcing. As in this case we'll need to provide the investment in form of money to hire a facility from other industry and the hired site will do the needful for us.
And this can be considered as a site transfer project and apart from money the parent site need to transfer the manufacturing process, analytical methods, safety studies etc etc. The profit which can be generated from this might be low but when compared to nothing, something is good and above all these we are able to fulfill the customer requirement.
That's it.....!!!
If you have any queries feel free to comment....!!
If any other means of enhancing capacity were there pl mention in the comments sections or mail me, i'll append those in this post.
Comments are most appreciated...!!!
Related Articles:
Bond Energy calculations
Calculate Product Assay in liquid ?
Calculate NPSH - Net Positive Suction Head
How to Calculate height required for vapour column of batch reactor ?
About The Author
Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.
Follow Me on Twitter AjaySpectator & Computer Innovations
Follow Me on Twitter AjaySpectator & Computer Innovations
