Effective Cleaning, Efficient Heat Exchangers

Though relatively new to the African market, Conco low-pressure mechanical cleaning systems are relatively new to the African market. Yet, they have proved to be a more effective alternative that high-pressure cleaning in removing stubborn fouling in tubes of condensers and heat exchangers of power-generating plants. Contented high-profile clients in the petrochemical and power generation sectors can attest to the technology’s efficacy. In Africa, the technology is available from Lesedi Nuclear Services.

Industries with power-generating plants have to ensure that their most treasured assets are well managed at all times. For this reason, regular maintenance should be a standard practice implemented devotedly. In power-generating plants, cleaning tubes of heat exchangers and condensers is a core part of routine maintenance. Thus, it is essential that effective techniques be explored, if need be.

The need for effective cleaning 

Tubes of heat exchangers and condensers must be cleaned thoroughly. This is because heat exchangers and condensers meet the process heating and cooling requirements of power-generating plants.  While in use, the tubes of heat exchangers and condensers are subject to the build-up of fouling over time, which reduces their efficiency and in some cases completely blocks the tubes. That’s why tube cleaning is a regular maintenance activity carried out normally once per year. Nonetheless, this requirement may vary depending on the severity and speed of the fouling.

Alternative techniques 

It has been observed that traditional techniques, despite their advantages in some applications fail in others. And in the latter cases, there would be sufficient grounds for alternative methods to be explored. Traditionally, the cleaning of heat exchangers and condenser tubes has been accomplished using high-pressure water jets, chemical flushing or ultrasonic cleaning processes.

In a brief to industry, through Mining Business Africa, the team of engineers at Lesedi Nuclear Services says that it views low-pressure mechanical tube cleaning of heat exchangers or condensers as a viable alternative technique. This is based on evidence gathered from success in clients’ projects where the technique has been used.

The team shares with industries with power generating plants several pertinent points relating to its experience, mainly in the following areas: Lesedi’s low-pressure tube cleaners as an effective alternative, and their approach to addressing clients’ needs; and successes.

Low-pressure mechanical tube cleaning 

To overcome the disadvantages of the traditional techniques, Conco Services LLC in the USA developed a solution using low-pressure mechanical tube cleaners. Lesedi is the African agent for these tube cleaners. The tube cleaners have a series of spring-loaded blades which scrape the fouling from the inside of the tube wall. The cleaners are individually manufactured to the exact dimensions of the tube inside diameter to avoid damaging the surface of the tube wall.

The cleaners are pushed through the tubes using low-pressure water. The water also flushes the dislodged fouling out of the front of the tube leaving a clean tube inside the surface. This then restores the Heat Exchangers and Condensers to their design efficiency. Offering convenience, the tubes can either be cleaned in situ in a vertical or horizontal position or on the ground in a designated area.

Lesedi approach (Scope of Work)

Lesedi utilises the ConcoTM low-pressure technology in projects. Typically, its Scope of Work is to clean the inside surfaces of the tubes in the nominated Heat Exchangers or Condensers to either restore their efficiency or prepare them for IRIS Inspection. The Client is responsible for isolating the Heat Exchangers or Condensers and removing the header boxes. Lesedi then supplies all the tools, equipment, and consumables, performs the cleaning, and hands the units back after acceptance by the Client.

Successes 

Thus far, the deployment of Conco low-pressure technology in mechanical cleaning tasks for clients has proved effective – going beyond expectations in most cases.  Interestingly, Eskom and Sasol have endorsed the Concor low-pressure tube cleaning technique. Cleaning tests were performed for the two clients at various locations throughout South Africa. This involved comparison between the output of low-pressure mechanical cleaning and traditional low-pressure mechanical cleaning. So impressed were the two corporations that they didn’t hesitate to sign several low-pressure mechanical tube cleaning contracts.

Now, Lesedi is an approved Low-Pressure Mechanical Tube Cleaning vendor to Eskom, Sasol and Natref. To date, Lesedi has successfully cleaned 122,432 Heat Exchanger and Condenser tubes with zero lost time injuries. The team at Lesedi is eager to take on board new contracts. Using recent breakthroughs as a springboard, it aims to achieve notable milestones in the field of low-pressure mechanical tube cleaning.

Opportunities are opening up in the mining sector. Presently, mining companies are ramping up production to benefit from high commodity prices – an endeavour that needs a reliable supply of energy from their power-generating plants. On its part, Lesedi is aiming to play a role through the provision of low-pressure mechanical cleaning of the heat exchanger and condenser tubes.

Services awareness drive

Core to the company’s growth plan involves going all out to aggressively raise awareness. This is because Lesedi’s low-pressure mechanical tube cleaning systems are relatively new to the African market. Due to this, clients are not aware of their benefits. And so, the team is willing to go all out in a publicity drive.

As part of the initiative, Lesedi is willing to perform test cleaning of Heat Exchangers and Condensers so that Clients can compare them with their traditional tube cleaning activities. The company hopes this will allow clients to decide which tube cleaning system to use in the future based on actual cleaning results.

In addition to the results of the cleaning activities, clients can also assess the improved safety of using low-pressure water, the improved environmental impact of using small quantities of water and the reduced footprint of the low-pressure tube cleaning systems allowing adjacent maintenance activities to continue in parallel.

Guarantee of efficiency and reliability 

Last but not least, the team affirms the distinctive quality of Lesedi’s cleaning systems: “A reliable energy supply depends on the efficiency of several processes. Heating and Cooling using heat transfer equipment forms a major component of those processes. Lesedi’s low-pressure mechanical tube cleaning systems guarantee the efficiency and reliability of the heat transfer equipment used to produce energy. Lesedi’s tube cleaning activities are performed safely, quickly, and efficiently which in turn improves the efficiency of the energy supply process.”

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ConcoTM cleaning systems 

Lesedi uses three Conco cleaning systems available which are selected based on the severity of the tube fouling. These are:

• Conco TruFit™

When it comes to fast, efficient heat exchanger tube cleaning, the ProSeries 200B Tube Cleaning System has no equal. The two-gun pump system uses safe water pressure, to propel TruFit™ tube cleaners through fouled tubes, removing deposits, corrosion, and obstructions in a single shot.

At the heart of the system are Conco TruFit™ tube cleaners. Manufactured by Conco, each tube cleaner is designed to eliminate specific types of fouling and is sized for the exact tube dimensions to ensure safe, effective tube cleaning.

• Conco MiteeMouse II™

The MiteeMouse II™ uses a drill bit mounted on the tip of a rotating Rod and a water flush to remove debris. As the rod rotates, the unit pumps water through the rod to weep holes in the drill bit, flushing away hardened deposits as they are loosened. This system is used for full and very hard fouling conditions.

• Conco Excaliber™

The Excaliber incorporates rotary tube cleaning action with a water flush to remove fouling deposits in heat exchanger tubes. No electricity is required. This powerful technology uses only plant air and water to operate and is safe to use in any location. Armed with the proper brush, the unit will scour off deposits and flush tubes clean in a single, efficient operation.

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Lesedi excels at Sasol

Heat exchanger maintenance in the petrochemical environment is normally carried out during a Shutdown. This means the work has to be carried out safely in the shortest possible time.

This was no exception at the Sasol Synfuels complex in Secunda. Lesedi was given a Project to clean heat exchanger tubes so that Sasol could compare Low-Pressure Mechanical Tube Cleaning with traditional High-Pressure Water Cleaning.

Before the start of the Project, a site walk down was convened to assess the location of the heat exchangers and the proximity of the power, compressed air and water supplies. The information gathered during this site visit was used to Schedule the work and assemble the required tools and equipment. All the tools, equipment and consumables required to perform the work were supplied by Lesedi. 

Meetings were also convened during this site visit with the relevant client stakeholders, safety, maintenance and production to ensure all their requirements were fully complied with before the start of work. On completion of the cleaning task, Lesedi’s Low-Pressure Mechanical Tube cleaning results far exceeded Sasol’s expectations in several areas. Specifically, three areas stood out – short time is taken, small footprint, and improved water efficiency.

• Shorter time

The time taken to clean the Heat Exchanger tubes was considerably shorter than that taken by HP Cleaning. This is an important feature, especially in a Shutdown situation. 

• Small footprint

Due to the extremely high pressures required by HP Cleaning and the associated dangers, a large area must be cordoned off during HP Cleaning. This in turn restricts any other maintenance work being carried out in the surrounding area.  However, low-Pressure Mechanical Tube Cleaning has a very small footprint allowing maintenance activities to continue around the Heat Exchangers being cleaned.

• Water efficient

The quantity of water used for Low-Pressure Mechanical Tube Cleaning is considerably less than that required by HP Cleaning. This is an environmental advantage and reduces the amount of water required for the process and to be treated on completion of the cleaning activities.

All in all, the Low-Pressure Mechanical Tube Cleaning provided a greater level of tube cleanliness compared with other tube cleaning processes. The efficiency of the Heat Exchangers was fully restored to their “as new” levels. In those cases where IRIS Inspections were required, the tubes were cleaned to the satisfaction of the IRIS Inspector allowing the relevant reports to be provided to Sasol.

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A Major EPC and EPCM

Originally evolved from Intens Engineering, founded in the 1980s, Lesedi has since grown into a major Engineering, Procurement, Construction and Construction management (EPC and EPCm) company. To date, Lesedi has completed projects in the nuclear, industrial power generation, mining, and oil and gas sectors. These include Construction and Maintenance Projects at Koeberg Nuclear Power Station, Medupi Coal Fired Power Station, Ankerlig Gas Turbine Power Station, and Sasol East and West in Secunda.

Lesedi is a Level three Broad-Based Black Empowerment Enterprise (B-BBEE), with a strong focus on localisation and empowerment, employing more than 300 people, including 76 qualified engineers and technicians with extensive nuclear, power, and Oil & Gas expertise, as well as technicians, artisans, semi-skilled and administrative support personnel, and highly experienced project management professionals.

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