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Combined Heat and Power (CHP) is the simultaneous production of electricity and heat energy from
a single source of fuel.
This project uses the new technology device called Bowman Power Micro Gas Turbine model TG80CG to
generate 80 kWe of electricity and up to 150 kWth of thermal energy. The overall thermal efficiency
obtained is above 80%, which is classified as Energy Efficient & Environmental Friendly equipment.
This project will be the first project embarked by Gas Malaysia Sdn Bhd on the Energy Efficiency
or Conservation for Industrial Application. This project is inline with the Government Policy
(implemented through the Energy Commission) to develop and promote awareness within the industrial
sector of the utilization of energy in an efficient and economical manner.
The main project objective is to develop and demonstrate CHP application to industrial customers,
which would be beneficial to the customer, Gas Malaysia and the Nation.
Bowman Power Limited of the United Kingdom was founded in 1994. Bowman Power currently offers
fully integrated, compact, lightweight and virtually vibration free CHP unit.
Figure 1 shows the inside of the Bowman Micro turbine TG80CG.
Figure 1: Bowman TG80CG
The Bowman Micro Gas Turbine TG80CG technology is based on five key areas of technology, Turbo
Alternators to produce 80 kWe of electrical power, Recuperators (heat exchanger) to get higher
electrical efficiency (about 26%), Power Conditioners to convert the electrical power output with
superior power quality to meet the customer needs, Waste Heat Recovery Boiler to provide 150 kWth
of thermal energy for water heating and Gas Boost Compressor to provide pressurized natural gas at
5.8 bar (85 psi).
This CHP system is most applicable in industries where the heating requirement is greater than the
electricity requirement.
The demo project is located in an existing Gas Malaysia?s customer in Senawang, Negeri Sembilan. Oon
Corporation Resources Sdn. Bhd. owns a Rubber Glove factory that produces 40 million rubber gloves per
month. 70% energy requirement within the factory is for heating using natural gas, and only 30% for
electricity. The overall energy costs contribute to about 30% of the total production cost.
The 80 kWe of electricity generated will be utilized to support the factory?s electrical requirement
which consumes around 180 kWe per hour. The 150 kWth of thermal energy will be used to supply hot water
and hot gas for their leaching tank (heating) and curing oven, respectively.
The manufacturing process for rubber gloves consists mainly of latex dipping, water heating and
curing. Figure 2 as shown below is a single line diagram to demonstrate the rubber glove production
process.
Figure 2: Rubber Glove Production Process
Natural gas is the main energy used for direct heating using infra-red burners to produce hot air
and hot water. The production process working temperature is within the range of 80˚C for the leaching
process and 150˚C for the drying and curing ovens.
The use of Infra-red burners is a conventional method of water heating and drying (or curing) in
the rubber glove manufacturing process. Natural gas is used as the energy source to heat-up the ceramic
and mesh wires within the infra-red burners. The transfer of heat is by radiation. Overall efficiency
of using the infra-red burners for the process is very low.
Within the CHP system, the hot water from the Bowman Micro Gas Turbine TG80CG waste heat recovery
boiler is piped to the leaching tanks through a heat exchanger and the exhaust will be ducted to the
curing oven.
Figure 3 below shows the site installation of the Micro Gas Turbine at the existing rubber glove
manufacturing factory.
Figure 3: Bowman CHP Unit at Site
The objective of the CHP installation other than to produce 80 kWe of electricity is to utilize
80˚C of hot water for the leaching process and to use the 150˚C hot exhaust for the curing process.
The installation is carried out in two phases. Phase I is to have the Micro Gas Turbine and its
ancillaries (Gas Boost Compressor and Safety Gas Train) installed at site.
In the Figure 4 shows the natural gas piping installation.
Figure 4: Natural Gas Piping Installation
The incoming natural gas from the existing factory?s 2 inch pipeline at 1.4 bar (20 psi) working
pressure is filtered, and the gas consumption is metered through a digital flow meter. The incoming
1.4 bar natural gas is regulated to 0.4 bar before being connected to a Gas Boost Compressor via
isolation and non-return valves. The Gas Boost Compressor is used to compress the gas from 0.4 bar
to 5.8 bar, before entering the Micro Gas Turbine. An additional safety feature called the Safety
Gas Train is connected after the outlet of the Gas Boost Compressor to provide tripping mechanism
if the pressure goes below 4.8 bar and higher 6.5 bar. Stainless steel tubing (SS 316) is used to
connect the outlet of the Safety Gas Train to the fuel input of the Micro Gas Turbine.
The water piping to and from the Micro Gas Turbine is divided into Primary and Secondary Loop. The
3 inch Primary water piping is a close loop system connecting the Micro Gas Turbine?s waste heat
recovery boiler output at 90˚C to a Alpha Laval Heat Exchanger and the 70˚C return to the Micro Gas
Turbine?s boiler input. The water flow rate for the Primary close loop is kept constant at 108
litre/minute by adding an external pump rated at 133 litre/minute. Figure 5 shows the Primary water
close system loop.
Figure 5: Primary Water Close System Loop
The Secondary water system loop connects the secondary side of the Alpha Laval Heat Exchanger to
500 litres stainless steel tank and to the Leaching tanks (for 5 production lines). Utility water supply
at 30 ˚C is used to recover the heat transfer from the primary close loop system in order to obtain a
temperature raise up to 80 ˚C. The 80 ˚C hot water is then stored into the 500 litres tank before being
piped directly to the Leaching tanks. Figure 6 shows the Secondary side water piping system from the
Heat Exchanger to the 500 litres hot water storage tank and from the storage tank to the Leaching tanks
within the factory.
Figure 6: Secondary Water Piping System with Alfa Laval Heat Exchanger and Stainless Steel Storage Tank
The secondary water piping system is capable of delivering 50 litre/minute continuous hot water at
80˚C to the leaching tanks.
The Micro Gas Turbine is programmed and connected to the factory 415 Vac electrical panel in
Grid-Connect mode. The Micro Gas Turbine acts as a current source providing 74 kWe of electrical
power to the factory at site condition. The 260 Amps Earth Leakage Circuit Breaker (ELCB) is used
to electrically connect the Micro Gas Turbine to the local grid electrical system. Figure 7 below
shows the sub distribution panel used for this purpose.
Figure 7: Sub Distribution Electrical Panel for Bowman MGT Unit
Phase II installation is to channel the Micro Gas Turbine 150˚C hot exhaust to the Curing Oven
(for 1 production line only). Phase II will be carried-out after having Phase I is continuously in
production. Currently the hot exhaust is being ducted to the atmosphere through a 400 mm diameter
ducting.
The total project estimated cost to be borne by Gas is RM440,444. The estimated project breakdown is
as shown in Table 1 below:
| Item |
Description |
Amount, RM |
| 1. |
One unit Bowman Turbogen TG80 CG |
367,990 |
| 2. |
Energy Audit |
10,000 |
| 3. |
System Integration and Installation |
62,454 |
| Total: |
440,444 |
Table 1: Capital Expenditure
In order to demonstrate the Energy Efficiency of the CHP system, pre and post energy audits need
to be carried out at the factory. Energy Cost savings is expected after CHP is implemented within the
factory. Electricity charges from TNB are expected to be reduced as 80kW electricity is self-generated
from the Micro Gas Turbine.
The calculation below is the expected natural gas consumption used for the Micro Gas Turbine fuel.
Micro Gas Turbine rated output power = 80 kWe (ISO condition)
Thermal Efficiency, η = 0.26
1 kWe = 860 kCal/ hour
NG CV = 9530 kCal/Sm3 (HHV)
From this info, we can calculate the Micro Gas Turbine fuel consumption per year (in mmBtu), on the
assumption of 8000 hours per year continuous operation.
Energy audits before and after installing the CHP unit is required in order to quantify the energy
savings. It is expected that:
(i) Reduction in electrical charges due to self-generation, where 74 kWe of electricity will be provided
by the Micro Gas Turbine. Estimated reduction of electrical charges is calculated as shown as below:
Electricity unit rate is RM0.258/kWh based on TNB Tariff D.
(ii) Reduction in the use of heating element, e.g. infra-red and ring burners at the leaching tank,
estimated at natural gas flow rate of 28 Sm3/hour or 50 units of burners. The calculation for the
natural gas consumption in the burners is as shown as below:
Based on natural gas pricing tariff E, commodity charge of RM12.87/mmBtu, the savings is calculated
as below:
(iii) Potential increase in natural gas consumption from the Micro Gas Turbine fuel consumption
8,446 mmBtu/year (or 704 mmBtu/month).
(iv) Simple payback period to demonstrate the potential of the return for this energy efficient
demo project is calculated as per the formula shown below:
Gas Boost Compressor with Safety Gas Train
Circulation Pump
Bowman MGT Side view
This CHP demo unit will not only be the first but it will set a benchmark for efficient
utilization of natural gas within the Rubber Manufacturing industry throughout the country.
kW - kilowatts
mmBtu - million British Thermal Unit
RM - Ringgit Malaysia
CHP - Combined Heat & Power
ELCB - Earth Leakage Circuit Breaker
TNB - Tenaga Nasional Berhad
HHV - High Heating Value
CV - Calorific Value
NG - Natural Gas
MGT - Micro Gas Turbine
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