Energy Saving in Boiler Plants

• Dual fuel steam boilers in a governmental laundry plant
• Diesel fuel steam boilers in a governmental hospital
• Gas fuel steam boilers in a governmental hospital
• Diesel fuel steam boilers in a governmental hospital
• Gas fuel steam boilers in a governmental hospital
• Electrical steam boilers in a correctional centre
• Electrical steam boilers in an operation threater
• Hot water boilers in a governmental hospital

Energy Saving in Chiller Plants

• 6000RT Direct seawater cooled chillers in a governmental hospital
• Indirect seawater cooled chillers in a commercial building
• 3000RT Direct seawater cooled chiller in a commercial building

Steam boilers in a governmental laundry plant

Background

Water fed to the steam boilers is treated by water softener. Chemicals including oxygen scavenger, anti-corrsion agent and pH booster are added. Although the water hardness is within the specification (i.e. <5ppm), mineral scale is still deposited on the fire tube but in a slower rate. Annual acid wash is needed to reduce the energy loss.

In order to cut the energy cost, four HydroFLOW units were installed to the water feed pipe of boilers in the beginning of March 2007. Fuel consumption for the following three months of the boiler plant was analyzed.

Result

At the end of April 2007, one of the boiler was in maintenance. The fire tubes were inspected by the user's technician and confirmed tubes were cleaner than before.

The fuel consumption was found 18% lower than the same period of last year.

TOP

Background

Water fed to the steam boilers is treated by water softener. Chemicals including anti-scaling agent, oxygen scavenger, anti-corrsion agent and pH booster are added. Although the water hardness is within the specification (i.e. <5ppm), mineral scale is still deposited on the fire tube but in a slower rate. Annual acid wash is required to reduce the energy loss.

In order to stop the anti-scaling agent due to its cost, one HydroFLOW unit was installed in January 2005 to the water feed pipe of one boiler as a pilot. The chemical was stopped at the same time. Fuel consumption for the following year was analyzed.

Result

In the beginning of January 2006, the boiler was in maintenance. The fire tubes were inspected by the user and confirmed tubes were cleaner than before. Although a thin layer of substance was coated on the tube surface, it was tested by Hong Kong Polytechnic University to be the anti-corrosion substance.

The fuel consumption was found at least 10% lower than the previous year.

The other two steam boilers were then equipped with HydroFLOW since 2006.

TOP

Background

Water fed to the steam boilers is treated by water softener. Chemicals including oxygen scavenger, anti-corrsion agent and pH booster are added. Although the water hardness is within the specification (i.e. <5ppm), mineral scale is still deposited on the fire tube but in a slower rate. Annual acid wash is needed to reduce the energy loss.

In order to reduce the energy loss due to the deposit of mineral scale, two HydroFLOW units were installed to the water feed pipe .

Result

In 2006, the boiler was in maintenance. The fire tubes were inspected by the user and confirmed tubes were cleaner than before. The dissolved scale was washed away simply by a pressurized water jet instead of applying acid.

TOP

Background

Water softener is broken and the water hardness is fail to meet the specification, mineral scale is deposit on the fire tube. Annual acid wash is needed to reduce the energy loss.

In order to find an alternative for the water softener so as to reduce the water hardness, three HydroFLOW units were installed to the three steam boilers in the plant.

Result

With the effect of HydroFLOW, the water hardness is found to be well within the specfication (i.e. <5ppm). In 2006 the fire tubes were inspected by the user and confirmed tubes were cleaner than before.

Since the installation of HydroFLOW, the water softener is no longer used!

TOP

Background

Water fed to the steam boilers is treated by water softener. Chemicals including oxygen scavenger, anti-corrsion agent and pH booster are added. Although the water hardness is within the specification (i.e. <5ppm), mineral scale is still deposited on the fire tube but in a slower rate. Annual acid wash is needed to reduce the energy loss.

In order to reduce the energy loss due to the deposit of mineral scale, two HydroFLOW units were installed to the water feed pipe.

Result

In 2005, one of the boiler was in maintenance. The fire tubes were inspected by the user and confirmed tubes were cleaner than before. Mineral scale was much thinner after three months of the installation of HydroFLOW. The remaining mineral scale was washed away simply by a pressurized water jet instead of applying acid.

TOP

Background

Water fed to the steam boilers is treated by water softener. Chemicals including oxygen scavenger, anti-corrsion agent and pH booster are added. Although the water hardness is within the specification (i.e. <5ppm).

However the energy cost increases as the thickness of mineral scale increases and eventually causes the burn out of the filament in one year.

In order to reduce the energy cost and replacement cost of filament, four HydroFLOW units were installed.

Result

Without the HydroFLOW, the filament is heavily coated by mineral scale in yellowish white colour as shown in the right.

After two months of operation with HydroFLOW installed, the existing scale on the filement was dissolved. Since then, no failure of heater due to mineral scale is reported.

TOP

Background

Water fed to the steam boilers is untreated because the steam generated is used for sterilization of surgical instruments.

Due to the size of the steam boiler, the corresponding energy loss is insignificant. However mineral scale coated on the heater filament causes its failure within a short time.

In order to reduce the replacement cost of filament and help to reduce energy loss, two HydroFLOW units were installed.

Result

After three months of operation with HydroFLOW installed, the heater filament was found to be clean. The old scale was mostly dissolved and only some residues remain at the end of it.

The thick scale formed inside the container was started to dissolve as can be seen from the picture on the right.

TOP

Background

Three hot water boilers are used to heat up calorifiers which provides hot water to the hospital. Even though the primary hot water is in a close loop and chemical treatment is employed, mineral scale is formed on the tube surface which cause a significant energy loss.

To reduce the energy cost, one HydroFLOW unit was installed to the header pipe of hot water return in the beginning of March 2007. The gas consumption was monitored for the following months.

Result

After three months of operation, the gas cost was dropped by 8.3%.

TOP

Background

The six chillers are directly cooled by seawater which is circulated through cooling towers. Due to the high concentration of minerals in seawater, the mineral scale deposits onto the condenser tube surface at a much higher rate than if fresh water is used.

To reduce the energy loss and produce sufficient cooling capacity, the condenser is cleaned with diluted hydrochloric twice a year.

In September 2006, one of the chillers was chosen and HydroFLOW unit was installed to the condensing water supply pipe. The installation was completed in one day. The Coefficient of Performance (COP) of the chiller was monitored for the following three months.

Result

After two months of operation (three weeks in exact due to the non continuous operation), the condenser was opened for visual inspection and was found that hard scale originally deposited on tube surface was softened and partially washed away.

The softened scale could be completely removed by a piece of tissue as shown in the middle area of the 'After' picture.

The COP was improved by 9%.

In the beginning of March 2007, the remaining five chillers were equipped with HydroFLOW units.

TOP

Background

The four chillers are indirectly cooled by seawater which is circulated through cooling towers. Due to the high concentration of minerals in seawater, the mineral scale deposits onto the plate heat exchanger (PHE).

Owing to the growth of micro-organism, biological fouling is formed consequently. Therefore the heat transfer coefficient of the PHE is substantially reduced.

To reduce the energy loss and produce sufficient cooling capacity, the plates are cleaned by pressurized water jet foolowed by a brushing to remove mineral scale once every four months.

In May 2007, one of the PHE was chosen and AquaKLEAR unit was installed to the condensing water supply pipe. The installation was completed in an hour.

Due to the non dedicated configuration of the PHEs and chillers, The improvement of Coefficient of Performance (COP) of that particular chiller can be used as an indication, so the differential temperature difference between the primary and secondary side of the PHE (Delta T) is analyzed.

Result

After one month of operation, the PHE was opened for visual inspection and was found that fouling was started wash away as shown in 'After (1)'. However the management could not wait any longer due to insufficient cooling, the plates were therefore cleaned in the beginning of June 2007. The delta T was slightly improved by the same time.

In September 2007, the PHE was opened again for inspection. The plates were slightly fouled ('After (2)') only after three months of operation. The residues on the plate could be removed easily by a piece of tissue.

The Delta T increased slightly in the first month and was flattened in the subsequent months. Therefore transformed energy saving was more than 7%.

TOP

Background

The chiller plant of the commercial building produces more than 11,000RT refrigeration power. Chillers are cooled directly by seawater in once through mode and so there is no problem of mineral scale.

Chlorine is used to minimize the development of biological fouling caused by the growth of micro-organism. However its concentration is governed by rules due to the harmful effect imposed to the water environment. As a result the biological fouling problem cannot be eliminated.

In order to improve the COP of those chillers, two 3000RT chillers (namely chiller#1 and chiller#2) were chosen as the pilot with an AquaKLEAR unit installed to chiller#1 in the beginning of September 2006 to see its effect on biofouling. Chiller#2 acts as a reference for the subsequent comparison.

Result

After 10 weeks of operation, the condenser of chiller#1 was opened and inspected. Tubes were clean when compared with the previous condition. Biofouling was not found on the tube surface.

The data logged by the existing BMS showed that there was an increasing trend of COP of chiller#1 since the installation of AquaKLEAR. The improvement of COP finally reached beyond 10%.

By December 2007, two additional AquaKLEAR units were installed to another 3000RT and 1500RT chillers.