To who it may concerns. I-Ravenna, March 11 th, 2016 HEAT EXCHANGER MAINTENANCE

Transcription

1 To who it may concerns. I-Ravenna, March 11 th, 2016 HEAT EXCHANGER MAINTENANCE

2 Page 2 out of 7 1 INTRODUCTION Nuova Saimar offers a highly specialized service for the maintenance of all kinds of heat exchangers and in order to offer a full multi-brand service, can also supply heat exchangers spare parts of all major manufacturers, such as Tranter, Swep, Reheat e Jucker, Alfa Laval, Gea, Apv, Sondex, Schmidt Bretten, etc. Nuova Saimar provides ordinary maintenance work (both scheduled and on-demand) and extraordinary maintenance work. The high quality of our services has been reached thanks to a longstanding expertise achieved in the collaboration with the major industrial groups, in different fields and in different process applications. The correct functioning of an heat exchanger, according to the design data, directly affects productivity and therefore of the production costs of the finished product. Unfortunately, all the exchangers, due to the nature of the fluids that pass through it, tents to get dirty with the subsequent performance drop as heat conveyer. To reduce the impact of performance decay on product cost, it is necessary to supervise the exchanger and schedule an appropriate maintenance. Here is the advantages of heat exchanger cleaning: to prevent holes or cut on the exchange surfaces due to corrosion, to keep the heat exchange efficient, and consequently the design temperatures; to avoid the increase of the pressure drop due to deposits or impurities. 2 SCALE AND EFFECTS Here is a list of the main kind of scales: Particulate scales Corrosion scales Biological material deposit scales Crystallization scales Chemical reaction scales Freeze scales Scale of a plate heat exchanger Scale of a tube bundle heat exchanger Scale is usually due to multiple causes, and tends to grow over time. The Tubular Exchanger Manufacturers Association (TEMA, 1988) recommends, in the design phase, to take into consideration a reasonable scale, so that the exchanger can be used also if dirty, although the cleaning cannot be avoided.

3 Page 3 out of 7 3 EXCHANGERS MAINTENANCE 3.1 Scheduled and Ordinary Maintenance A scheduled maintenance allows to lengthen exchangers working live and to keep on having the same performances they had been designed for. Furthermore, a preventive ordinary maintenance allows also, in the long terms, to save money, as its costs is lower than an extraordinary maintenance, occurring, for example, in case of sudden interruption. Extraordinary maintenance entails often the full replacement of the exchangers or very expensive intervention. Nuova Saimar gives to its Clients the possibility to schedule a continuous Maintenance Plan that foresees regular surveys of the heat exchangers and of their working conditions. 3.2 Extraordinary Maintenance In some cases, due to a particularly critical condition of either the heat exchanger or some of its components, the Client is compelled to require an extraordinary intervention. Also in this event, Nuova Saimar is able to provide a highly qualified service and all the necessary know-how. 4 MAINTENANCE INTERVENTION PROVIDED BY NUOVA SAIMAR Before any kind of intervention on the heat exchanger, it is necessary to carry out a series of activities, in order to: Determine the kind of fouling for the correct choice of the cleaning product to be used; Evaluate the clogging level of the heat exchanger Evaluate the different options for the treatment and dumping of the cleansers used (eco-friendly); Evaluate numbers and dimensions of the exchangers to be treated for the correct choice of the cleaning unit; Determine the presence of suitable nipples. Maintenance intervention on heat exchangers can be carried out both on-site and at Nuova Saimar s premises. 4.1 Cleaning The dirt layer that piles up over time on the surfaces hinders the heat exchange and worsen the performances. For this reason it is necessary to keep cleaned the surfaces. In general, heat exchangers cleaning can be divided into two categories: Chemical washing; Mechanical and/or hydrodynamic washing. One method does not exclude the other: it is possible, for example, to perform before a chemical washing and then a high-pressure cleaning.

4 Page 4 out of Chemical Washing For the heat exchanger cleaning, it is possible to submit the heating surfaces (for example, plates, tube handle, ) to flushing cycles either with acid or basic solutions, depending on the kind of scale and on the material the heat exchanger is made of. The operation requires a fixed time and a close check of the ph of the washing solution. Tube heat exchanger before chemical washing Exchanger during chemical washing Tube heat exchanger after chemical washing In case of plate heat exchanger, at the end of the chemical washing cycles, each plate is 100% visually inspected and also a further test using vegetable penetrating fluid to highlight possible cracks or holes that cannot be seen naked eyes. A further rinsing can be carried out to remove liquid residuals penetrated from the plate surface Hydrodynamic and/or Mechanical Cleaning To clean mechanically or with high pressure water all the heat exchanger components it is assumed that the heat exchanger is out of service and disassembled in the major possible number of parts, so as to grant the access even to the remotest points. In case of tube heat exchanger, the tube bundle shall be first of all extracted, to clean the external surface, while in case of plate exchangers, cleaning is carried out plate by plate. Hydrodynamic Cleaning inside the tubes Hydrodynamic Cleaning outside the beam

5 Page 5 out of 7 During cleaning operations, it is important to be extremely careful not to damage the different components and bear in mind that sometimes the removal of scales may bring to further losses. Every time impurities, obstructions, deposits are been removed, components surfaces are taken back to bare metal. For the heat exchanger tube bundle, specific tools are used, such as PIG (flexible buffers), brushes and pipe cleaners, based on the kind of residual that shall be removed. The mechanical action can be drawn by a high pressure water jet (starting from 200 bar) and in some cases as propulsion fluid it can be used a mixture with air and water. The advantage in using water is the possibility to collect the flowing out fluid and analyse the scale typology. For example, by evaporating the water used during cleaning and weight the residual, it is possible to calculate the scale rate of the exchanger. In order to grant to our Client the highest quality degree and an extremely low intervention time, Nuova Saimar is equipped with different kind of high and very high pressure (up to 1300 bar) motor pumps, specific equipment for robotic washing of tube heat exchangers, shells, liners, pipelines and a containers. Robots, feed by very high pressure pumps, work independently; it is required only the presence of the two operators, one for each robot. CRANCKSET REPLACEMENT Heat exchanger gaskets are subject to usury, and substitute them before they get too damaged means avoid losses and serious damages, and, over time, it means costs and time saving. During our maintenance activities, all gasket are replaced with high quality gaskets, glued with a special non-hardening component, in accordance with the gaskets original technical specification that allow to avoid further thermal treatment, as vulcanization, that is however available on demand or for particular kind of gasket. This special kind of gluing that we use eases the following maintenance operation carried out on the plant. The same of the tube heat exchanges. In our cranckset replacement intervention we pay particular attention to the gaskets material that shall be used, as they shall be compatible with process fluids, with the plate kind and material, and with the technical features, as the pressure levels for which the exchanger has been designed.

6 Page 6 out of 7 Gaskets replacement Plates ready to be assembled Reclosing of a big plate heat exchanger 4.2 REGENERATION Equipped with a highly qualified technical department, Nuova Saimar can offer a regeneration service of the whole exchanger, for example: Tube bundles, perforated flanges, baffles substitution; Plates substitution and / or repair in whatever material; Accessories (tie rods, nozzles, flanges) substitutions; Pressure test with certificated and calibrated pressure gauges ; Non destructing testing; Technical assistance for Recertification procedures Heat Exchanger before pipes substitution Tube exchange during pipes substitution

7 Page 7 out of 7 Pressure Test Tube bundle repair thought titanium welding At your disposal for any further information, Best regards NUOVA SAIMAR srl C.E.O. Gianfranco Lucchi