General Features:

-> DEF: series of production equipment used to make non reversible chemical-physical transformation of materials through a fixed technological routing.

-> CHAR:

• Fixed/ obliged technological routing;
• Trasformations are non reversible;
• Sectors: Petrochemical, oil refineries, cement, glass, rubber, paper production.
• Products are mainly uses in secondary industrieseeeeeee

-> MODELS:

• Work load model;

Example: Cement

-> DEF: hydraulic binder.

• Can be mixed with water and poured to set as a solid mass or use ingredient in making mortar or concrete.

-> MANUFACTURE:

• DRY PROCESS: raw materials are ground and dried to raw meal in the form of a flowable powder. The dry raw meal is fed to the preheater or precalciner kiln or, more rarely, to a long dry kiln.
• SEMI-DRY PROCESS: the dry raw meal is pelletised with water and fed into a grate preheater before the kiln or to a long kiln equipped with crosses.
• SEMI-WET PROCESS: the slurry is first dewatered in filter presses. The resulting filter cake is extruded into pellets and then fed either to a grate preheater or directly to a filter cake dryer for raw meal production
• WELT PROCESS: the raw materials (often with a high moisture content) are ground in water to form a pumpable slurry. The slurry then is either fed directly into the kiln or first to a slurry dryer.

FLOW SHEET CEMENT MANUFACTURING:	ASME PROCESS DIAGRAM

Physical flow:

-> Raw materials are converted to Finished Products through production stages

-> CHAR of innovative plants:

• Capital expensive: Big systems, based on big investment (to achieve the economies of scale);
• Economy of scale;
• Automatization (machinaries are controlled by disance;
  • Relevance of technological parameters of the production process (temperatures, pressures, …);
  • Significant investment in sensors, equipment control, etc;
  • Control often automated with supervisory intervention.

• Simple production logistics: for natural consequences of fixed technological routing.

-> Pipelines (operate in continuous & discontinuous flow) are based in serial transporters;

-> Are designed into the plant structure;

-> Products have few variants and may require few materials within the product recipe;

• Simple production management: Management decision al limited to two main problems; batch sizing (is the number of production campaigns) + batch sequencing.
• High plant utilization and equipment efficiency:

-> High production volumes + Stable volumes through time => economically-reasonable investment.

-> Economies of scales can be better achieved with higher plant sizes.

-> Batch Process: more inefficients are du e to the inherent characteristics of this type of production.

• Low need for workforce;
• Qualitative characteristics of products stable.
• Low flexibility:

-> Limited set of products, batch wise production: due to batch sizing and sequencing;

-> Plats are not easily reconfigured/ re convertion.

• High risk of obsolescence: facility lifetime is related to products lifetime.
• Significant impact of failures: there are some degree of parallelization/ reducancy but not much. It depends on the type of production: batches 🔻 criticla; continuous 🔺 critical.
• Importance of variations in process conditions.

Kynd of plants:

-> Plants are designed to operate:

• CONTINUOUS FLOW production process: materials are moved continously through the production equipement of the plant;
• BATCH PRODUCTION process: materials are processed as batches (is discontinuous transformation thanks to storages).

-> Logically speaking are the same, but physically are different (continuous and batch productions).

📌 SEVESO LAW: is the European Law that impose that only chemical engineer can design chemical plants.

• Tha name was taken by the Seveso that was fill up by pollution from a chemical plant that was destroied.

Continuous Flow:

-> TECHNOLOGICAL ROUTING: it’s lead to identify all the production equipment types that are needed and, amongst them, the bottleneck.

• APC calculated considering typical losses;
• APC and demand are compared to verify the design choices.

-> STEPS:

• Steps 1 – 2 basically these are dependent on the knowledge of the process (e.g. chemical engineers) and the subsequent constraints; an industrial engineer can basically understand but it is dependent on the technological options available on this side, and constraints;
• Step 3 – 4 once he/she has understood, the industrial engineer can basically support the study of the plant structure, starting from the bottleneck, in order to calculate the APC > Hence, (understood the process constraints) a first clear indication is available on the bottleneck for the production flows > TPC is known > therefore an evaluation of APC based on SR and A (concepts of coefficient losses).
• Step 4 remember the fact that the SR may be dependent on the process constraints -> if we do not operate at standard process conditions (i.e. either warm-up or different conditions from process conditions at the nominal / standard regime), the SR may be a different value, respect to the best value;
• Step 5 few options may be available, for ex. duplicating some equipment but this should be clearly verified with knowledgeable engineers on the process.

Rough Design:

1. Define the production flows according to the technological routing required for the product
2. Identify all the production equipment types that are needed and the bottleneck
3. Define the theoretical production capacity

where

• TPC = theoretical production capacity in [ton/hour], or other similar units, i.e. [kg/hours]

4. Calculate the actual production capacity

 where

• A = line availability (0 < A 1)
• SR = scrap rate     (0  SR < 1) (varying according to the process conditions kept in the system)

5. Compare the actual production capacity and the demand. If necessary, modify the line and go back to step 2

-> EXAMPLE:

Batch Process:

-> TECHNOLOGICAL ROUTING: leads to identify all the production equipement types that are needed.

• Yearly workload and # of available hours Nhi and Ahi are calculated for each type of production equipment i, considering all typical losses.
• # of production equipment of type i Nmi necessary to produce the production mix is then calculated.

-> CHAR:

• Batches of different products can be concurrently produced in the differen equipment.
• More intermittent management cycle: each equipment may be producing, in different campaigns, different products.

(We can produce differnt type of nylon in the same time).

• 🔽 VOLUME => 🔽 productivity.
• Mid flexibility & mid range production mix.
• Similar to job shop (logially, physically are very different).

-> STEPS:

• Steps 1 – 2:  basically these are dependent on the knowledge of the process (e.g. chemical engineers) and the subsequent constraints; an industrial engineer can basically understand but it is dependent on the technological options available on this side, and constraints;
• Step 3 – 4: once he/she has understood, the industrial engineer can basically support the study of the plant structure, starting from the bottleneck, in order to calculate the APC > Hence, (understood the process constraints) a first clear indication is available on the bottleneck for the production flows > TPC is known > therefore an evaluation of APC based on SR and A (concepts of coefficient losses).
• Step 4: remember the fact that the SR may be dependent on the process constraints -> if we do not operate at standard process conditions (i.e. either warm-up or different conditions from process conditions at the nominal / standard regime), the SR may be a different value, respect to the best value;
• Step 5: few options may be available, for ex. duplicating some equipment but this should be clearly verified with knowledgeable engineers on the process.

Rough Design:

-> ASSUMPTIONS:

• Equipment are used according to Batch wise processing approach: to change from one to another is required a setup for the new campaign;
• Setup time are required and do not depend on the productio (batch) sequences.

-> STEPS:

1. Identify the production mix
2. Define the production flows according to the technological routing required for the products (in the production mix)
3. Identify all the production equipment types that are needed
4. Calculate yearly workload and number of hours available for each type of production equipment i
5. Calculate the number of production equipment of type i necessary to produce the production mix

📌 There is a production mix (within a limited range) considering that some functional departments can be identified.

Number Hours:

=> Yearly workload NH_i for production equipement i:

Annual Hours:

-> # of hours available for each type of production equipment i

Number Product Equipment:

-> Number of production equipment of type i necessary to produce the production mix:

Evaluate the Yearly Costs:

• Overall plant costs: include costs of al the production equipment acquired to build the plant;
• m: coefficient used to split costs on plant/facility lifetime;
• Overall operation costs: may include different types of cost (energy costs, maintenance, raw material)

-> EXAMPLE:

-> AUTOCLAVE: bigo oven where the material is cooked continuously.