“Defense” is a word that has gained value in production processes, especially when there are variables that get out of control; when there is something that can and should be done and not when, unfortunately, it gets out of hand, especially when thousands of dollars have been lost and perhaps even the life of an operator has been claimed.
In industry there are numerous processes that require special protection, such is the case of what happens in chemical reactors.
What is a chemical reactor?
A chemical reactor is a processing unit designed so that one or more chemical reactions are carried out inside. The chemical reaction is that unitary operation that aims to distribute the atoms of certain molecules (reacting compounds or reactants) differently to form new ones (products). Said processing unit is made up of a closed container, which has input and output lines for chemical substances and is governed by a control algorithm.
Main functions of chemical reactors
Among the main functions are the following:
- Ensure the type of contact or way of flow of the chemical products (reactants) inside the tank, to achieve a desired mixture.
- Provide sufficient contact time between substances.
- Allow conditions of pressure, temperature and composition so that the reaction takes place to the degree and at the desired rate taking into account the thermodynamic and kinetic aspects of the reaction.
Forms of chemical changes
- Decomposition: It consists of a molecule dividing into smaller molecules, atoms or radicals.
- Combination: This is done when a molecule or atom joins with another species to form a new compound.
- Isomerization: In this case, the molecule does not carry out any external decomposition or addition to another, it is simply a change in internal structural configuration.
Classes of chemical reactions
- Homogeneous Reactions: When only one phase is affected, whether gaseous, solid, or liquid.
- Heterogeneous Reactions: When the presence of at least two phases is required for the reaction to take place at a desired rate.
- Enzymatic Reactions: They use biological catalysts (proteins with high molecular weight, with active centers, and that work at low temperatures).
- Catalytic Reactions: These are those reactions that require an additional substance (that does not appear in the overall balance) to modify the reaction rate; This substance, by its mere presence, causes the chemical reaction, a reaction that would not otherwise occur.
- Non-Catalytic Reactions: The reactant materials do not need any additional substance to give rise to the chemical reaction.
- Autocatalytic Reactions: In this reaction, one of the products formed acts as a catalyst, participating in another stage of the process where the reaction speed is faster than in the first.
- Endothermic Reactions: These are those that adsorb heat from the outside.
- Exothermic Reactions: These are those that release heat to the outside.
Among the variables to control in a reactor are temperature, humidity, ph and especially pressure, the latter being the variable most susceptible to changes and where it requires a true “defense” to prevent it from getting out of control. Pressure is a variable that is measured as force per unit area. When considering a process in a chemical reactor, the pressure can change abruptly from one point to another (pressure pulses) or can go from being a positive to a negative pressure (cyclic process). In this case, it is necessary that this “defense” be capable of interacting with these changes without becoming fatigued or damaged before its time. It is important to mention that abrupt or uncontrolled pressure rise can cause the reactor to rupture suddenly, causing irreparable damage and can even cause someone’s death.
The rupture disc, a defense against an abrupt change in pressure
The rupture disc is a device that starts from a thin sheet capable of opening at a pressure and temperature such that it allows the relief of the reactor through a pipe conduit when it is not capable of controlling the pressure, allowing the energy product of the overflowing reaction to be evacuated. The device is manufactured under conventional international standards such as ASME Section VIII and must be designed to “defend” against the constant attack of fatigue, product and abrupt pressure pulses.
FIKE Corporation for over 75 years has been at the forefront of rupture disc design and manufacturing. The FIKE reference disc RD320 is the optimal solution for the overpressures that can occur in a chemical reactor; This comes in sizes ranging from ½” to 12” and working pressures from 7 psig to 600 psig.
With a patented design called G2, the disc is capable of withstanding high cycling and complex polymerization processes, thanks to the wide range of materials in which they are manufactured. Additionally, it has films based on FEP or PTFE that prevent chemical attack with the base material, such as 316 L stainless steel.
This element breaks at the set pressure with unparalleled accuracy, which does not require moving parts such as safety or relief valves, where they become clogged, causing the spring to get stuck; This does not happen with the rupture disc, always guaranteeing the integrity of the reactor.