Basic principles of ICCP system
Pipeline corrosion represents a serious problem in medium/long distance fluid distribution, primary in case of underground installations.
Stray currents are one of the major cause of buried pipeline corrosion damage; this phenomenon can happen due to several reasons but basically the following are the most common as it is shown in picture below.
This occurs because two materials with high potential difference located into an electrolyte solution generate electron migration. Ground made of rocks, sand, mud and so on is a perfect electrolyte scenario for stray currents to appear.
Cathodic protection is a well know practice to prevent serious damage to water, gas and oil distribution from DC stray currents. There are two ways to perform a cathodic protection: through a sacrificial anode or by using the best available technology of the impressed current protection.
As explained in illustration above a rectifier drives the corrosion current to simulate the anode corrosion.
Remember that Cathodic Protection means: the reduction or elimination of corrosion by making a metallic structure cathodic with respect to the electrolyte in which it is installed.
Impressed current method is the most efficient way to perform a cathodic protection.
This is because it can be applied in variety of applications and with flexibility; adjustable voltage and current outputs; protection of large areas; automatically controlled.
The system consists of a buried pipeline, sacrificial anodes, a AC/DC rectifier and an energy source.
Choosing a proper anode material such as high silicon chromium, bearing cast iron, treated graphite or mixed metal oxides it has been observed that the anode itself has a very low consumption rate.
When and for what? To protects large structures; to protects structures that require large amounts of current; to replace depleted galvanic systems.
Yet, the most common limitation to this technology is that external energy source is required. Commonly 8 to 30Amp of current is consumed for pipeline protection. This means 30 to 105 MWh per year (5k to 15k€ a year at 15cent per kWh). This energy is provided directly from the grid (where available), from solar panels (when far from the grid) or alternative solutions. Solar panels are seen today as an unreliable solution due to unpredictable productivity and because they are commonly stolen.
LocPower as strategic investment to protect your pipeline
LocPower is an innovative and patented control valve with integrated turbine and “extra-flow” channel which makes it unique in the world of industrial products.
A control valve represents a typical dissipative instrument: during flow or pressure control a pressure drop is achieved across the Control Valve to do its job as describe in illustration below.
Power is the product of flow rate, pressure drop and density and therefore a control valve (hereafter PRV) which is controlling 200 l/s of water with a pressure loss of 3 bar is dissipating 58 kW of hydraulic power; this means 508 MWh/year of lost energy (more than €77k/year considering Italian price of industrial energy of 0.153€/kWh).
Until this moment there was only one way to harness part of this energy: the installation of a turbomachinery system.
The traditional pipeline energy recovery system is realised by installation of a turbine in parallel to a control valves for extra flow (flow rates greater than turbine nominal flow rate) and in series with another control valve to handle minimum flow. Everything connected with substantial piping layout as shown in figure below.
There are numerous cases and applications where this solution is not feasible due to the location limitations (vertical installation or underground places) as shown on the picture below.
In such hard to reach places energy recovery becomes easier with LocPower, thanks to its unique design.
LocPower is a high performance, remotely controlled, industrial control valve, with stainless steel body, industrial modulating actuator (electric or pneumatic), with an integrated turbine coupled to a synchronous electric generator which can harvest from 60 to 75% of dissipated energy.
The most common usage of LocPower® clean electricity in industry is the on-site consumption (e.g. to a pumping station or a water treatment station) and selling it to the grid.
Another feasible way to “implement” this clean energy is to feed up the impressed current cathodic protection system.
In this way your control valve ensures overall pipeline integrity and recovers clean energy so that you can save on the energy bills and protect the pipeline network from corrosion.