MAINTENANCE OF BOILERS AND CIRCUITS
Pirobloc offers a comprehensive maintenance service for the industrial heating circuits.
The review service seeks to know at all times the state of its facilities and to be able to carry out the necessary preventative maintenance. On this basis, Pirobloc offers the possibility of technical specialists carrying out periodic visits to its facilities (annual or biannual), reviewing the following sections:
- Thermal fluid analyses
- Burners: state and yields
- Electrical recirculation pump groups
- Manual and automatic valves
- General behavior of the installation
- Analysis of the performance of the boiler
- Adaptation of the installation to current legal regulations
Additionally, we have a remote management service, i.e., for assisting with your installation remotely. You can use this service by contacting our SAT Department.
When preventative maintenance is not possible due to the poor state of an installation or the incorrect operation of any of its components, we offer a repair service that allows resuming the production process reliably and safely.
Moreover, we also offer a circuit cleaning service, consisting of the replacement of the thermal oil installation at the end of its useful life. The useful life of the thermal fluid of the installation depends on the usage regime in the process. Depending on the existing thermal fluid analysis, we create a specific protocol for each case, with the proper cleaning procedure. This is a comprehensive service that includes the following steps:
- The complete emptying of the installation.
- The supply of detergent fluid.
- Dehumidification circuit.
- Filling with the new thermal fluid.
- Notify the competent company in each region, the collection of used thermal oil. In each case, the time required for the cleaning process will be studies, according to the parameters of the existing installation of thermal fluid.
Pirobloc carries out an inspection of the equipment and prepares the post-inspection report, which indicates whether the installation has passed the inspection satisfactorily or whether a problem has been detected and corrective measures have to be taken to correct this problem.
The post-inspection reports contain four main sets of information:
- Information on the installation: brand, owner, type, registration date, category, panel, etc.
- Characteristics of the heater inspected: components included, fluids contained, maximum pressure, volume or nominal diameter, maximum and minimum temperatures, etc.
- It also specifies the type of inspection that has been carried out (level A, B or C), as well as the date on which the next inspection should take place.
- List of problems encountered (if any). A piece of equipment can be qualified on three levels depending on whether or not faults have been found:
- Favourable qualification: when no defect has been found (level 0).
- Conditional qualification: minor defects to be corrected as soon as possible (level 1), or serious defects to be corrected within the indicated time frame (level 2).
- Failed qualification: critical defects that force the installation to be taken out of service (level 3).
It should be recalled that the operator of the installation is responsible for carrying out periodic inspections and for ensuring the proper conservation and maintenance of the installation. Moreover, the agents involved in the installation or modification of the installation (designer, execution and installation manager and installation company) are responsible for their actions in the installation. The holder and the agents mentioned are obliged to:
Take the appropriate measures so that the corrections, repairs or modifications ordered in the review report are carried out within the established time frame:
- If minor defects (level 1) have been detected, it is recommended that they be corrected as soon as possible and always before the next periodic inspection is carried out.
- If serious defects (level 2) have been detected, they must be corrected within a certain period of time after the inspection of the installation has been carried out.
- If critical defects (level 3) have been detected, the installation cannot be started until these are corrected and a new inspection is carried out to verify that this has been done.
HOW TO PROLONG BOILER LIFE
Every boiler manufacturer has its own design which will have a direct effect on the length of the boiler’s useful life as well as its efficiency in relation to the circuit it heats.
As well as the boiler design, there are other factors which also contribute towards extending a thermal fluid heater’s life:
- Using oil in good condition, so efficient at heat transfer. For this purpose, we recommend checking its condition regularly. Remember that if it is necessary to change the oil in the system at the end of its useful life, there are companies whose business is the free collection and reuse of oil.
- Recognising and heating the boiler’s control indications and alarms: ignoring warnings and/or alarms is not an option. In case of doubt, ask the manufacturer.
- Performing correct preventive maintenance and annual inspections of the boiler, consisting of checking combustion and smoke composition, smoke temperature, working temperatures and pressures, etc.
- Controlling pump consumptions and service flows, and checking whether there are leaks of the heat transfer fluid.
- Checking that the boiler body’s thermal insulation and heat transfer fluid system are in good condition.
- Keeping the interior of the boiler, smoke ducts and/or grilles and boiler ventilation ducts free of soot is indispensable for their correct operation.
PREVENTIVE MAINTENANCE TAKING THERMAL FLUID SAMPLES
One of the usual preventive maintenance operations in thermal fluid circuits is taking fluid samples for analysis.
PIROBLOC has a thermal fluid sample-taking device especially designed to carry out this operation properly. This system guarantees the sample’s temperature, and its correct extraction point, accessibility and safety. Our thermal fluid sample-taking device can be installed either on the installation’s main out pipe or the return pipe.
Traditionally, this operation has been carried out by dismantling measurement instruments and using cut-off valves as taps to extract the required samples. Maintenance personnel carrying out this operation put both themselves and the installation in jeopardy. To avoid these risks, Pirobloc offers a safe, simple alternative to obtain representative samples without interrupting the process. This system notably reduces the potential fire hazards caused by carrying out this operation inadequately.
Its working is simple. Initially, valves A and C are closed. When you want to take the heat transfer fluid sample, open valve A until the system’s expansion bottle is partly full. Then allow the fluid in the bottle to cool (valve B must be open to expel the gases resulting from the expansion). When the thermal fluid is cold, after making sure that valve A is closed, open valve C and fill the sample recipient.
THERMAL FLUID HEATER FLOW CONTROL
Thermal oil is the heat transfer fluid used in countless applications for industrial processes. From the point of view of the end process or heat consumer, the thermal fluid is the primary fluid. However, if the analysis or control volume is restricted to the boiler, the thermal fluid is the secondary fluid, because the heat exchange takes place from the primary fluid (which may be a flame, combustion gases or in electrical energy transformed into heat) to the secondary fluid (thermal oil). Because the primary fluid temperatures can be very high, it is essential that an oil flow is ensured sufficient to prevent its maximum working temperature being exceeded or overheating points being produced in the boiler.
The rated power of the standard PIROBLOC’s standard dual-coil boiler range for fossil fuels (natural gas, diesel fuel or fuel oil) runs from 100,000kcal/h (116kW) up to 5,000,000 kcal/h (5814kW). They all have flow measurement with a level below which heating is cut off to prevent overheating which could crack the oil and/or damage the boiler. This flow measurement is carried out by the pressure difference between the oil inlet and outlet pipes.
The rated pressure differences for this boiler range vary from 1.8 to 2.8 bar, depending on the particular boiler and project.
Typical set points for this alarm vary from 1 to 1.8 bar, depending on each case, with which a system flow alarm for low pressure differential can be implemented with a differential pressure switch (liquid) (DPSL) or from the difference readings of two pressure transmitters (PT), one in the inlet pipe and the other in the outlet.
From the hydraulic point of view, electric thermal fluid heaters are reasonably similar to a shell and tube heat exchanger, the tube bundle being replaced by the set of pins which are supplied with electricity to heat the oil moving through the shell.
The rated power of PIROBLOC’s standard electric thermal oil heater range runs from 24 kW up to 4.000 kW.
The rated pressure differential values for this boiler vary between 0.1 and 0.3 bar. This low pressure differential is because the distance oil moves in an electric boiler is much less than in a coil, and its speed is also lower. This would lead to the flow pressure differential alarm set point being between 0.05 and 0.15 bar, which would cause a problem for standard differential pressure sensors (bearing in mind that the static pressure may reach 15 barg or higher).
The solution adopted by PIROBLOC is to insert a restriction orifice plate, the characteristics of which have been calculated following ISO_5167-2 (Measurement of fluid flow by means of pressure differential devices), in the boiler inlet. This calculation is carried out individually for every customer and project depending on its work conditions: characteristics of the fluid used (density and viscosity) and rated flow.
Using this element, the differential pressure of the blade boiler assembly is around 1.2 bar, enabling use of standard instruments for differential pressure measurement. As well as this advantage, the boiler’s behaviour becomes similar to that indicated in ISO 5167 Part 2, enabling the flow to be measured with great accuracy at any time.