Lime Scale Removal: Heat Exchanger Cleaning

Heat exchangers in many manufacturing facilities are crucial in everyday operations. Heat exchangers are designed to transfer heat in the form of kinetic energy from one liquid to another. And while transferring heat, the heat exchanger, over a period of time will collect lime, scale and rust on the waterside of the exchanger. (fouling in heat exchangers)

With Dynamic Descaler® lime scale remover you do not have to dismantle or remove the unit from your operations. You may want to install a system, which will inject Dynamic Descaler® into your water supply on a regular basis for your cooling tower, chiller, or your closed loop water system. This procedure will eliminate downtime in your everyday operations while cleaning out your exchanger.

Instructions for Dynamic Descaler® Cleaning

If you just intend to clean out the heat exchanger, you still do not have to dismantle or remove the exchanger from your operations.

1. By-pass heat exchanger from operation.

2. Remove the existing water in the exchanger. This MUST be done, to insure proper results.

3. Disconnect the water in/out connections from the exchanger.

4. Attach the necessary hoses to in/out connections on the exchanger to a circulating pump. Refer to chart (see download) for necessary circulation of time and the amount of Dynamic Descaler® to be used.

5. Once the circulation has been completed, flush the exchanger with water to remove any insoluble material.

Fouling in heat exchangers is the prime reason for the increase in energy, maintenance, and operational cost and the retardation of heat transfer!

Fouling of heat exchangers in processing industries is a chronic operating problem. Costs due to over-design, additional fuel consumption and maintenance, loss of production, etc. have been estimated as 0.25% of the GNP of industrialised countries. In addition to the appropriate selection of operating conditions and exchanger geometry, there are numerous chemical and mechanical methods to mitigate fouling and to remove deposits from the heat transfer surfaces. However, all methods to reduce fouling require some understanding of the mechanisms of the deposition process and of the structure and adhesion of deposits on the heat transfer surfaces.

What is Fouling?

Fouling is generally defined as the accumulation of unwanted materials on the surfaces of processing equipment. It has been recognized as a nearly universal problem in design and operation and affects the operation of equipment in two ways:

Cost Due to Fouling

Despite the enormous costs associated with fouling, only very limited research has been done on this subject. Reliable knowledge of fouling economics is important when evaluating the cost efficiency of various mitigation strategies. The total fouling-related cost can be broken down into four main areas:

According to Pritchard and Thackery (Harwell Laboratories), about 15% of the maintenance costs of a process plant can be attributed to heat exchangers and boilers, and of this, half is probably caused by fouling.

Fouling can be very costly in refinery and petrochemical plants since it increases fuel usage, results in interrupted operation and production losses, and increases maintenance costs. Panchal (Argonne National Laboratory), based on the study of Van Nostrand, re-estimated the energy and economic penalties associated with heat exchanger fouling for the US refineries, as more than $2 billion per year. The maintenance costs in the USA were revised because they have increased significantly due to recent environmental regulations.

Typically, cleaning costs are in the range of $40,000 to $50,000 per heat exchanger per cleaning. Garrett-Price and Pritchard found that total heat exchanger fouling costs for highly industrialised countries such as the US and the UK are about 0.25% of the countries’ gross national product (GNP). Steinhagen et al found that the fouling costs for New Zealand are 0.15% of the New Zealand GNP, which is less than for industrialised countries. Using these percentages, Müller-Steinhagen lists total fouling related costs for various countries based on 1992 US$.

DYNAMIC DESCALER® Heat Exchanger Cleaning Instructions

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