ā§Ģā§Ļā§Ļ āĻেāĻি āĻ্āϝাāĻĒাāϏিāĻি āĻā§াāĻļিং āĻāĻāύিāĻে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦ্āϝāĻŦāĻšাāϰে āĻŽাāϏিāĻ āĻ্āϝাāϏ āĻāϰāĻ ā§§ā§Ģ–⧍ā§Ļ% āĻāĻŽাāύো āϝাā§। āĻাāύুāύ āĻāϰ āĻŦৈāĻ্āĻাāύিāĻ āĻŦিāĻļ্āϞেāώāĻŖ āĻ āĻŦাāϏ্āϤāĻŦ āĻĒ্āϰā§োāĻ।
Using a heat exchanger in a 500 kg capacity washing unit can reduce monthly gas consumption by 15–20%. Learn its scientific analysis and practical application.
đˇ āĻূāĻŽিāĻা (Introduction)
āĻĄেāύিāĻŽ āĻā§াāĻļিং āĻļিāϞ্āĻĒ āĻŦাংāϞাāĻĻেāĻļেāϰ āĻ āύ্āϝāϤāĻŽ āĻļāĻ্āϤিāĻļাāϞী āĻā§āĻĒাāĻĻāύ āĻাāϤ। āĻŦāϰ্āϤāĻŽাāύে āĻĻেāĻļেāϰ āĻļāϤ āĻļāϤ āĻাāϰ্āĻŽেāύ্āĻāϏ āĻ āĻā§াāĻļিং āĻĢ্āϝাāĻ্āĻāϰিāϤে āĻĒ্āϰāϤিāĻĻিāύ āĻŦিāĻĒুāϞ āĻĒāϰিāĻŽাāĻŖ āĻ্āϝাāϏ āĻāϰāĻ āĻšāĻ্āĻে āĻļুāϧু āĻā§াāĻļিং āĻ āĻĄ্āϰাā§িং āĻĒ্āϰāĻ্āϰিā§াā§ āĻĒাāύি āĻāϰāĻŽ āĻāϰাāϰ āĻāύ্āϝ | The denim washing industry is one of the strongest manufacturing sectors in Bangladesh. Currently, hundreds of garment and washing factories in the country consume a huge amount of gas every day just to heat the water in the washing and drying process.
āĻিāύ্āϤু āĻĒ্āϰāϝুāĻ্āϤিāĻāϤ āĻāĻĻ্āĻাāĻŦāύেāϰ āĻŽাāϧ্āϝāĻŽে āĻāĻ āĻāϰāĻ āĻāĻŽাāύো āϏāĻŽ্āĻāĻŦ। āĻāϰ āĻŽāϧ্āϝে āϏāĻŦāĻেā§ে āĻাāϰ্āϝāĻāϰ āϏāĻŽাāϧাāύ āĻšāϞো Heat Exchanger System (āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āϏিāϏ্āĻেāĻŽ) | But it is possible to reduce this cost through technological innovation. The most effective solution among these is the Heat Exchanger System.
āĻāĻāĻি āĻāĻŦেāώāĻŖা āĻ āύুāϝাā§ী, āĻāĻāĻি ā§Ģā§Ļā§Ļ āĻেāĻি āĻ্āϝাāĻĒাāϏিāĻি āĻā§াāĻļিং āĻāĻāύিāĻে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āϏ্āĻĨাāĻĒāύ āĻāϰāϞে āĻŽাāϏিāĻ āĻ্āϝাāϏ āĻāϰāĻ āĻĒ্āϰাā§ ā§§ā§Ģ–⧍ā§Ļ% āĻĒāϰ্āϝāύ্āϤ āĻāĻŽাāύো āϏāĻŽ্āĻāĻŦ | According to a study, installing a heat exchanger in a 500 kg capacity washing unit can reduce the monthly gas consumption by about 15–20%.
āĻāĻ āĻāϰ্āĻিāĻেāϞে āĻāĻŽāϰা āĻŦিāĻļāĻĻāĻাāĻŦে āĻāϞোāĻāύা āĻāϰāĻŦ āĻীāĻাāĻŦে āĻāĻ āĻĒ্āϰāϝুāĻ্āϤি āĻাāĻ āĻāϰে, āĻেāύ āĻāĻি āĻাāϰ্āϝāĻāϰ, āĻāĻŦং āĻāϰ āĻ āϰ্āĻĨāύৈāϤিāĻ āĻ āĻĒāϰিāĻŦেāĻļāĻāϤ āĻĒ্āϰāĻাāĻŦ āĻী | In this article, we will discuss in detail how this technology works, why it is effective, and what its economic and environmental impact is.
đˇ ā§§. āĻā§াāĻļিং āĻāĻāύিāĻে āĻ্āĻŦাāϞাāύি āĻŦ্āϝāĻŦāĻšাāϰেāϰ āĻĒāĻāĻূāĻŽি (Background of Energy Use in Washing Unit)
āĻĄেāύিāĻŽ āĻā§াāĻļিং āĻĒ্āϰāĻ্āϰিā§াā§ āĻŦিāĻিāύ্āύ āϧাāĻĒে āϝেāĻŽāύ – Desizing, Enzyme Wash, Bleach, Tint, Neutralization, Softener, āĻāϤ্āϝাāĻĻি – āĻāώ্āĻŖ āĻŦা āĻāϰāĻŽ āĻĒাāύি āĻĒ্āϰā§োāĻāύ āĻšā§ | In the denim washing process, various steps such as Desizing, Enzyme Wash, Bleach, Tint, Neutralization, Softener, etc. require warm or hot water.
āĻāĻ āĻĒাāύি āϏাāϧাāϰāĻŖāϤ āĻŦā§āϞাāϰ āĻŦা āĻ্āϝাāϏ āĻšিāĻাāϰ āĻĻ্āĻŦাāϰা āĻāϰāĻŽ āĻāϰা āĻšā§, āϝেāĻাāύে āĻĒ্āϰāĻুāϰ āĻĒāϰিāĻŽাāĻŖ āĻĒ্āϰাāĻৃāϤিāĻ āĻ্āϝাāϏ (Natural Gas) āĻŦ্āϝāĻŦāĻšৃāϤ āĻšā§ | This water is usually heated by a boiler or gas heater, which uses a large amount of natural gas.
āĻāĻāĻি ā§Ģā§Ļā§Ļ āĻেāĻি āĻ্āϝাāĻĒাāϏিāĻি āĻā§াāĻļিং āĻāĻāύিāĻ āϏাāϧাāϰāĻŖāϤ āĻĻিāύে ā§§ā§Ļ–⧧⧍āĻি āĻŦ্āϝাāĻ āĻাāϞাā§। āĻĒ্āϰāϤিāĻি āĻŦ্āϝাāĻে ⧍ā§Ļā§Ļā§Ļ–⧍ā§Ģā§Ļā§Ļ āϞিāĻাāϰ āĻāϰāĻŽ āĻĒাāύি āϞাāĻে | A 500 kg capacity washing unit usually runs 10–12 batches a day. Each batch requires 2000–2500 liters of hot water.
āϧāϰা āϝাāĻ, āĻĒ্āϰāϤি āĻŦ্āϝাāĻে āĻĒাāύিāϰ āĻā§ āϤাāĻĒāĻŽাāϤ্āϰা ā§Ŧā§Ļ°C āĻ āϤুāϞāϤে āĻšāĻŦে; āϏেāĻ āϤাāĻĒāĻŽাāϤ্āϰা āĻ āϰ্āĻāύে āĻĒ্āϰাā§ ā§Šā§Ļ–ā§Šā§Ģ āĻেāĻি āĻ্āϝাāϏ āϞাāĻে | Let’s say that the average water temperature in each batch needs to be raised to 60°C; achieving that temperature requires about 30–35 kg of gas.
āĻāĻ āĻšিāϏেāĻŦে āĻĒ্āϰāϤিāĻĻিāύেāϰ āĻ্āϝাāϏ āĻāϰāĻ āĻšā§ āĻĒ্āϰাā§ ā§Šā§Ļā§Ļ–ā§Šā§Ģā§Ļ āĻেāĻি, āĻ āϰ্āĻĨাā§ āĻŽাāϏে āĻĒ্āϰা⧠⧝ā§Ļā§Ļā§Ļ–ā§§ā§Ļ,ā§Ļā§Ļā§Ļ āĻেāĻি āĻ্āϝাāϏ | This equates to a daily gas consumption of about 300–350 kg, or about 9000–10,000 kg of gas per month.
đˇ ⧍. āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻী āĻāĻŦং āĻāĻি āĻীāĻাāĻŦে āĻাāĻ āĻāϰে? (What is Heat Exchanger and How It Works)
đ¸ āϏংāĻ্āĻা (Definition)
Heat Exchanger āĻšāϞো āĻāĻŽāύ āĻāĻāĻি āϝāύ্āϤ্āϰ āϝা āĻāĻ āϤāϰāϞ (fluid) āĻĨেāĻে āĻ āύ্āϝ āϤāϰāϞে āϤাāĻĒ āϏ্āĻĨাāύাāύ্āϤāϰ āĻāϰে, āĻিāύ্āϤু āĻĻুāĻ āϤāϰāϞ āĻāĻāύোāĻ āĻŽিāĻļে āϝাā§ āύা।āĻā§াāĻļিং āĻāĻāύিāĻে āĻāĻি āĻŦ্āϝāĻŦāĻšৃāϤ āĻšā§ Hot Waste Water āĻĨেāĻে āϤাāĻĒ āĻĒুāύāϰুāĻĻ্āϧাāϰ (Heat Recovery) āĻāϰাāϰ āĻāύ্āϝ।
A heat exchanger is a device that transfers heat from one fluid to another, but the two fluids never mix. It is used in washing units to recover heat from hot waste water.
đ¸ āĻাāϰ্āϝāĻĒ্āϰāĻŖাāϞী (Working Principle)
- āĻā§াāĻļিং āĻŽেāĻļিāύ āĻĨেāĻে āĻŦেāϰ āĻšāĻā§া āĻāϰāĻŽ āĻĒাāύি (Temperature: 60–70°C) āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰে āĻĒ্āϰāĻŦাāĻšিāϤ āĻšā§। (The hot water (Temperature: 60–70°C) coming out of the washing machine flows into the heat exchanger.)
- āĻ āĻĒāϰ āĻĒাāĻļ āĻĻিā§ে āύāϤুāύ āĻ াāύ্āĻĄা āĻāύāϞেāĻ āĻĒাāύি (Temperature: 25–30°C) āĻĒ্āϰāĻŦাāĻšিāϤ āĻšā§। (New cold inlet water (Temperature: 25–30°C) flows through the other side.)
- āϧাāϤāĻŦ āĻিāĻāĻŦ āĻŦা āĻĒ্āϞেāĻেāϰ āĻŽাāϧ্āϝāĻŽে āĻāϰāĻŽ āĻĒাāύিāϰ āϤাāĻĒ āĻ াāύ্āĻĄা āĻĒাāύিāϤে āϏ্āĻĨাāύাāύ্āϤāϰিāϤ āĻšā§। (The heat from hot water is transferred to cold water through metal tubes or plates.)
- āĻāϰ āĻĢāϞে āĻ াāύ্āĻĄা āĻĒাāύি āĻĒ্āϰি-āĻšিāĻ āĻšā§ে āϝাā§, āϝাāϰ āϤাāĻĒāĻŽাāϤ্āϰা 40–45°C āĻĒāϰ্āϝāύ্āϤ āĻĒৌঁāĻে āϝাā§। (This results in the cold water being preheated, reaching a temperature of 40–45°C.)
- āĻāĻāύ āĻŦā§āϞাāϰে āĻĒাāύি āĻāϰāĻŽ āĻāϰāϤে āĻāĻŽ āĻ্āϝাāϏ āϞাāĻে, āĻাāϰāĻŖ āĻĒাāύি āĻāĻেāĻ āĻংāĻļিāĻ āĻāϰāĻŽ। (Now it takes less gas to heat water in the boiler, because the water is already partially heated.)
āĻāĻ āĻĒ্āϰāĻ্āϰিā§াā§ āĻĒ্āϰāϤিāĻি āĻŦ্āϝাāĻে ā§Ē–ā§Ģ āĻেāĻি āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āĻšā§, āϝা āĻŽাāϏিāĻāĻাāĻŦে āĻāĻāĻি āĻŦিāĻļাāϞ āĻ āĻ্āĻে āĻĒāϰিāĻŖāϤ āĻšā§।
This process saves 4–5 kg of gas in each batch, which adds up to a huge amount on a monthly basis.
đˇ ā§Š. āĻ্āϝাāϏ āϏাāĻļ্āϰā§েāϰ āĻŦিāĻļ্āϞেāώāĻŖ (Quantitative Analysis of Gas Saving)
đˇ ā§Ē. āĻĒ্āϰāϝুāĻ্āϤিāĻāϤ āĻāĻĒাāĻĻাāύ (Technical Components of Heat Exchanger System)
ā§§️⃣ āĻĒ্āϞেāĻ āĻাāĻāĻĒ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ (PHE) | Plate Type Heat Exchanger (PHE)
- āĻāĻাāϧিāĻ āĻĒাāϤāϞা āĻŽেāĻাāϞ āĻĒ্āϞেāĻ āĻĻিā§ে āϤৈāϰি, āϝেāĻুāϞোāϰ āĻŽāϧ্āϝে āĻāϰāĻŽ āĻ āĻ াāύ্āĻĄা āĻĒাāύি āĻāϞাāĻĻা āĻ্āϝাāύেāϞে āĻĒ্āϰāĻŦাāĻšিāϤ āĻšā§। Made of multiple thin metal plates, between which hot and cold water flow in separate channels.
- āϤাāĻĒ āĻāĻĻাāύ-āĻĒ্āϰāĻĻাāύে āϏāϰ্āĻŦোāĻ্āĻ āĻĻāĻ্āώāϤা (Efficiency: 80–90%)। Highest efficiency in heat exchange (Efficiency: 80–90%).
⧍️⃣ āĻļেāϞ āĻāĻŦং āĻিāĻāĻŦ āϤাāĻĒ āĻāĻ্āϏāĻেāĻ্āĻাāϰ | Shell and Tube Heat Exchanger
- āĻāĻāĻি āĻŦā§ āĻিāĻāĻŦেāϰ āĻেāϤāϰে āĻ āύেāĻ āĻোāĻ āĻিāĻāĻŦ āĻĨাāĻে; āĻāĻ āĻিāĻāĻŦে āĻāϰāĻŽ āĻĒাāύি, āĻ āύ্āϝāĻিāϤে āĻ াāύ্āĻĄা। A large tube has many small tubes inside; one tube has hot water, the other has cold.
- āϰāĻ্āώāĻŖাāĻŦেāĻ্āώāĻŖ āϏāĻšāĻ, āĻেāĻāϏāĻ āĻিāύ্āϤু Efficiency āĻিāĻুāĻা āĻāĻŽ (70–80%)। Easy to maintain, durable but slightly less efficient (70–80%).
ā§Š️⃣ āϤাāĻĒāĻŽাāϤ্āϰা āύিāϝ়āύ্āϤ্āϰāĻ āĻāĻŦং āϏেāύ্āϏāϰ | Temperature Controller & Sensor
- āĻāύāϞেāĻ āĻ āĻāĻāĻāϞেāĻ āĻĒাāύিāϰ āϤাāĻĒāĻŽাāϤ্āϰা āĻĒāϰ্āϝāĻŦেāĻ্āώāĻŖ āĻāϰে। Monitors the inlet and outlet water temperatures.
- āϏ্āĻŦā§ংāĻ্āϰিā§āĻাāĻŦে āϤাāĻĒāĻŽাāϤ্āϰা āύিā§āύ্āϤ্āϰāĻŖ āĻāϰে āϏāϰ্āĻŦোāĻ্āĻ āϏাāĻļ্āϰ⧠āύিāĻļ্āĻিāϤ āĻāϰে। Automatically controls the temperature to ensure maximum savings.
ā§Ē️⃣ āĻ āύ্āϤāϰāĻŖ āĻŦ্āϝāĻŦāϏ্āĻĨা | Insulation System
- āϤাāĻĒেāϰ āĻ āĻĒāĻā§ āϰোāϧ āĻāϰে āϏিāϏ্āĻেāĻŽেāϰ āĻĻāĻ্āώāϤা āĻŦাā§াā§। Increases system efficiency by preventing heat loss.
đˇ ā§Ģ. āĻŦাāϏ্āϤāĻŦ āĻĒ্āϰāϝ়োāĻেāϰ āĻāĻĻাāĻšāϰāĻŖ (Case Study)
đ āĻāĻĻাāĻšāϰāĻŖ | Example: “ABC Denim Washing Ltd.”
āĻ āĻŦāϏ্āĻĨাāύ | Location: āϏাāĻাāϰ, āĻĸাāĻা (Savar, Dhaka)
āĻŽেāĻļিāύ āĻ্āϝাāĻĒাāϏিāĻি | Machine Capacity: ā§Ģā§Ļā§Ļ āĻেāĻি | 500 kg
āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻāύāϏ্āĻāϞ | Heat Exchanger Installed: Plate Type, ⧍ā§Ļ⧍ā§Ē āϏাāϞেāϰ āĻাāύুā§াāϰিāϤে | Plate Type, January 2024
āĻĒূāϰ্āĻŦে āĻ্āϝাāϏ āĻāϰāĻ | Previous Gas Consumption: ⧝⧍ā§Ļā§Ļ āĻেāĻি/āĻŽাāϏ | 9200 kg/month
āĻŦāϰ্āϤāĻŽাāύ āĻāϰāĻ | Current Consumption: ā§ā§Ģā§Ģā§Ļ āĻেāĻি/āĻŽাāϏ | 7550 kg/month
āϏাāĻļ্āϰ⧠| Savings: ā§§ā§.⧝% (17.9%)
āĻ āϤিāϰিāĻ্āϤ āϏুāĻŦিāϧা | Additional benefits:
- āĻŦ্āϝাāĻ āĻাāĻāĻŽ ⧧⧍ āĻŽিāύিāĻ āĻāĻŽেāĻে। Batch time reduced by 12 minutes.
- āĻā§াāĻļিং āϰেāĻাāϞ্āĻে āĻোāύো āύেāϤিāĻŦাāĻāĻ āĻĒ্āϰāĻাāĻŦ āĻĒā§েāύি। There was no negative impact on washing results.
- āĻŦā§āϞাāϰ āĻĒ্āϰেāϏাāϰ āϏ্āĻ্āϝাāĻŦāϞ āĻĨাāĻāĻে, āĻāĻŽ āĻŦ্āϰেāĻāĻĄাāĻāύ। Boiler pressure remains stable, less breakdown.
āĻ āĻĨেāĻে āĻĒ্āϰāĻŽাāĻŖ āĻšā§, āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻļুāϧু āĻāϰāĻāĻ āĻāĻŽাā§ āύা, āĻĒ্āϰোāĻĄাāĻāĻļāύ āĻĢ্āϞোāĻ āĻāύ্āύāϤ āĻāϰে।
This proves that the heat exchanger not only reduces costs but also improves production flow.
đˇ ā§Ŧ. āĻ āϰ্āĻĨāύৈāϤিāĻ āĻŦিāĻļ্āϞেāώāĻŖ (Economic Impact)
āĻāĻি āĻĒ্āϰāĻŽাāĻŖ āĻāϰে āϝে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻšāϞো āĻāĻāĻি long-term profit-oriented investment।
āϝে āĻĢ্āϝাāĻ্āĻāϰি āĻŦāĻāϰে ⧧⧍ āĻŽাāϏ āĻাāϞু āĻĨাāĻে, āϤাāϰা āĻāĻ āĻŦāĻāϰেāϰ āĻŽāϧ্āϝেāĻ ā§§ā§Ģ–⧍ā§Ļ āϞাāĻ āĻাāĻা āύেāĻ āĻĒ্āϰāĻĢিāĻ āĻāϰāϤে āĻĒাāϰে āĻļুāϧুāĻŽাāϤ্āϰ āĻāύাāϰ্āĻি āϏাāĻļ্āϰ⧠āĻĨেāĻে।
This proves that heat exchangers are a long-term profit-oriented investment. A factory that operates 12 months a year can make a net profit of 15-20 lakh taka within a year from energy savings alone.
đˇ ā§. āĻĒāϰিāĻŦেāĻļāĻāϤ āĻĒ্āϰāĻাāĻŦ (Environmental Impact)
āĻ্āϝাāϏ āĻāϰāĻ āĻāĻŽāϞে āϤাāϰ āϏāĻ্āĻে āϏāĻ্āĻে āĻাāϰ্āĻŦāύ āύিāϰ্āĻāĻŽāύ (CO₂ Emission) āĻāĻŽে āϝাā§ | Reducing gas consumption also reduces carbon emissions (CO₂ emissions).
āĻĒ্āϰāϤি āĻেāĻি āĻ্āϝাāϏ āĻĻāĻšāύ āĻāϰāϞে āĻĒ্āϰা⧠⧍.ā§ā§Ģ āĻেāĻি CO₂ āĻā§āĻĒāύ্āύ āĻšā§ | Every kg of gas burned produces about 2.75 kg of CO₂.
āϝāĻĻি āĻŽাāϏে ⧍ā§Ļā§Ļā§Ļ āĻেāĻি āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āĻšā§, āϤāĻŦে CO₂ āύিāϰ্āĻāĻŽāύ āĻāĻŽāĻŦে āĻĒ্āϰাā§ ā§Ģ.ā§Ģ āĻāύ/āĻŽাāϏ āĻŦা ā§Ŧā§Ŧ āĻāύ/āĻŦāĻāϰ।
āĻāĻি āĻĒāϰিāĻŦেāĻļāĻŦাāύ্āϧāĻŦ āĻā§āĻĒাāĻĻāύেāϰ āĻĻিāĻে āĻāĻāĻি āĻŦিāĻļাāϞ āĻĒāĻĻāĻ্āώেāĻĒ | If 2000 kg of gas is saved per month, CO₂ emissions will be reduced by about 5.5 tons/month or 66 tons/year.This is a huge step towards environmentally friendly production.
āĻāĻাā§া, āĻ āύেāĻ LEED Certified Green Factory-āϤে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦ্āϝāĻŦāĻšাāϰেāϰ āĻŦাāϧ্āϝāĻŦাāϧāĻāϤা āϰā§েāĻে, āĻাāϰāĻŖ āĻāĻি āĻেāĻāϏāĻ āĻā§āĻĒাāĻĻāύেāϰ (Sustainable Manufacturing) āĻুāϰুāϤ্āĻŦāĻĒূāϰ্āĻŖ āϏূāĻāĻ | In addition, many LEED Certified Green Factories are required to use heat exchangers, as this is an important indicator of sustainable manufacturing.
đˇ ā§Ž. āĻ্āϝাāϞেāĻ্āĻ āĻ āĻāϰāĻŖীā§ (Challenges and Solutions)
đˇ ⧝. āĻāύ্āϤāϰ্āĻাāϤিāĻ āĻĒ্āϰেāĻ্āώাāĻĒāĻে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦ্āϝāĻŦāĻšাāϰেāϰ āĻĒ্āϰāĻŦāĻŖāϤা (Global Perspective)
āĻŦিāĻļ্āĻŦেāϰ āĻ āύেāĻ āĻĻেāĻļেāĻ āĻā§াāĻļিং āĻ āĻেāĻ্āϏāĻাāĻāϞ āϏেāĻ্āĻāϰে Heat Recovery System āĻŦাāϧ্āϝāϤাāĻŽূāϞāĻ āĻāϰা āĻšāĻ্āĻে | Heat Recovery System is being made mandatory in the washing and textile sector in many countries around the world.
- đ¯đĩ āĻাāĻĒাāύ | Japan: āĻā§াāĻļিং āĻ āĻĄাāĻং āĻāĻāύিāĻে Waste Heat Recovery System āϏ্āĻ্āϝাāύ্āĻĄাāϰ্āĻĄ | Waste Heat Recovery System standard in washing and dyeing units.
- đŠđĒ āĻাāϰ্āĻŽাāύি | Germany: Industrial Heat Reuse Project-āĻāϰ āĻŽাāϧ্āϝāĻŽে ⧍ā§Ģ% āĻāύাāϰ্āĻি āϰিāĻāĻাāϰি āĻাāϰ্āĻেāĻ | 25% energy recovery target through Industrial Heat Reuse Project.
- đ§đŠ āĻŦাংāϞাāĻĻেāĻļ | Bangladesh: āĻŦেāĻļ āĻিāĻু āĻļীāϰ্āώ āĻŦ্āϰ্āϝাāύ্āĻĄেāϰ LEED Gold Factory āϝেāĻŽāύ Envoy Textile, Green Textile Ltd. āĻāϤিāĻŽāϧ্āϝেāĻ āĻāĻ āϏিāϏ্āĻেāĻŽ āĻŦ্āϝāĻŦāĻšাāϰ āĻāϰāĻে | Several top brand LEED Gold factories such as Envoy Textile, Green Textile Ltd. are already using this system.
āĻŦাংāϞাāĻĻেāĻļে āĻāĻি āĻāĻāύো āϏীāĻŽিāϤāĻাāĻŦে āĻŦ্āϝāĻŦāĻšৃāϤ āĻšāϞেāĻ, āĻāĻŦিāώ্āϝāϤে Sustainability Compliance Audit-āĻ āĻāĻি āĻāĻāĻি āĻুāϰুāϤ্āĻŦāĻĒূāϰ্āĻŖ āĻŽাāύāĻĻāĻŖ্āĻĄ āĻšā§ে āĻāĻ āĻŦে।
Although it is still used to a limited extent in Bangladesh, it will become an important criterion in Sustainability Compliance Audit in the future.
đˇ ā§§ā§Ļ. āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āύিāϰ্āĻŦাāĻāύেāϰ āĻাāĻāĻĄāϞাāĻāύ (Heat Exchanger Selection Guidelines)
- āĻ্āϝাāĻĒাāϏিāĻি āĻŽ্āϝাāĻিং | Capacity Matching: āĻāĻĒāύাāϰ āĻā§াāĻļিং āĻŽেāĻļিāύেāϰ āĻĒাāύিāϰ āĻĢ্āϞো āĻ āϤাāĻĒāĻŽাāϤ্āϰা āĻ āύুāϝাā§ী āϏāĻ িāĻ āϏাāĻāĻ āύিāϰ্āĻŦাāĻāύ āĻāϰুāύ | Select the right size according to the water flow and temperature of your washing machine.
- āĻāĻĒাāĻĻাāύেāϰ āĻুāĻŖāĻŽাāύ | Material Quality: SS316 āĻŦা SS304 āĻ্āϰেāĻĄেāϰ āϏ্āĻেāĻāύāϞেāϏ āϏ্āĻিāϞ āĻŦেāĻে āύিāύ | Choose SS316 or SS304 grade stainless steel.
- āĻĻāĻ্āώāϤা | Efficiency: ā§Žā§Ļ% āĻŦা āϤাāϰ āĻŦেāĻļি Efficiency āϝুāĻ্āϤ āĻŽāĻĄেāϞ āĻŦেāĻে āύিāύ | Choose a model with 80% or more efficiency.
- āύিāϰাāĻĒāϤ্āϤা āĻাāϞāĻ āĻāĻŦং āύিāϝ়āύ্āϤ্āϰāĻŖ āĻŦ্āϝāĻŦāϏ্āĻĨা | Safety Valve & Control System: āĻ āĻোāĻŽেāĻেāĻĄ āĻāύ্āĻ্āϰোāϞ āύিāĻļ্āĻিāϤ āĻāϰুāύ | Ensure automated control.
- āϏ্āĻĨাāύীāϝ় āĻŦāύাāĻŽ āĻāĻŽāĻĻাāύি | Local vs Imported: āϏ্āĻĨাāύীā§āĻাāĻŦে āϤৈāϰি āĻŽাāύāϏāĻŽ্āĻŽāϤ āĻĒāĻŖ্āϝ āĻāĻāύ āĻĒাāĻā§া āϝাā§, āϝা āĻĻ্āϰুāϤ āϏাāϰ্āĻিāϏিং āϏুāĻŦিāϧা āĻĻেā§ | Locally made quality products are now available, which provides fast servicing facilities.
đˇ ā§§ā§§. āĻŦাāϏ্āϤāĻŦিāĻ āϏুāĻŦিāϧাāϏāĻŽূāĻš (Key Benefits Summary)
✅ āĻ্āϝাāϏ āĻāϰāĻ ā§§ā§Ģ–⧍ā§Ļ% āĻĒāϰ্āϝāύ্āϤ āĻāĻŽে āϝাā§ (Gas consumption is reduced by 15–20%)
✅ āĻĒাāύি āĻāϰāĻŽ āĻšāĻā§াāϰ āϏāĻŽā§ āĻāĻŽে, āĻŦ্āϝাāĻ āĻাāĻāĻŽ āĻোāĻ āĻšā§ (Water heating time is reduced, batch time is shortened)
✅ āĻŦā§āϞাāϰেāϰ āĻāĻĒāϰ āĻাāĻĒ āĻāĻŽে (Pressure on the boiler is reduced)
✅ CO₂ āύিāϰ্āĻāĻŽāύ āĻš্āϰাāϏ āĻĒাā§, āĻĒāϰিāĻŦেāĻļāĻŦাāύ্āϧāĻŦ āĻā§āĻĒাāĻĻāύ āύিāĻļ্āĻিāϤ āĻšā§ (CO₂ emissions are reduced, environmentally friendly production is ensured)
✅ ā§Ŧ–ā§Ž āĻŽাāϏেāϰ āĻŽāϧ্āϝেāĻ āĻāύāĻেāϏ্āĻāĻŽেāύ্āĻ āĻĢেāϰāϤ āĻĒাāĻā§া āϝাā§ (Investment is returned within 6–8 months)
✅ āĻĢ্āϝাāĻ্āĻāϰি LEED āĻ Compliance Score āĻŦৃāĻĻ্āϧি āĻĒাā§ (Factory LEED and Compliance Score are increased)
đˇ āĻāĻĒāϏংāĻšাāϰ (Conclusion)
āĻĄেāύিāĻŽ āĻā§াāĻļিং āĻĢ্āϝাāĻ্āĻāϰিāϤে āĻ্āϝাāϏ āĻāϰāĻ āĻāĻāĻি āϏ্āĻĨাā§ী āĻŦ্āϝā§েāϰ āĻā§āϏ। āĻāĻ āĻŦ্āϝ⧠āĻāĻŽাāύোāϰ āϏāĻŦāĻেā§ে āĻাāϰ্āϝāĻāϰ āĻ āĻেāĻāϏāĻ āĻĒāĻĻ্āϧāϤি āĻšāϞো Heat Exchanger System। āĻāĻāĻি ā§Ģā§Ļā§Ļ āĻেāĻি āĻ্āϝাāĻĒাāϏিāĻি āĻā§াāĻļিং āĻāĻāύিāĻে āĻāĻ āϏিāϏ্āĻেāĻŽ āĻĒ্āϰā§োāĻ āĻāϰāϞে āĻŽাāϏিāĻāĻাāĻŦে āĻĒ্āϰাā§ ā§§ā§Ģ–⧍ā§Ļ% āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āĻāϰা āϝাā§ — āϝা āĻŦāĻāϰে āϞাāĻ āϞাāĻ āĻাāĻাāϰ āϏāĻŽাāύ। (Gas consumption is a permanent source of cost in denim washing factories. The most effective and sustainable method to reduce this cost is the Heat Exchanger System. Applying this system in a 500 kg capacity washing unit can save about 15–20% gas per month — which is equivalent to lakhs of taka per year.)
āĻāĻāĻ āϏāĻ্āĻে āĻāĻি āĻĒāϰিāĻŦেāĻļāĻŦাāύ্āϧāĻŦ, āĻেāĻāϏāĻ āĻ āĻāύ্āϤāϰ্āĻাāϤিāĻ āϏ্āĻ্āϝাāύ্āĻĄাāϰ্āĻĄ āĻŽেāύে āĻāϞে। āϝে āĻĒ্āϰāϤিāώ্āĻ াāύ āϏāĻŽā§āĻŽāϤো āĻāĻ āĻĒ্āϰāϝুāĻ্āϤি āĻ্āϰāĻšāĻŖ āĻāϰāĻŦে, āϤাāϰাāĻ āĻāĻŦিāώ্āϝāϤেāϰ āĻĒ্āϰāϤিāϝোāĻিāϤাā§ āĻāĻিā§ে āĻĨাāĻāĻŦে। (At the same time, it is environmentally friendly, sustainable and complies with international standards. The companies that adopt this technology on time will be ahead of the competition in the future.)
đ "āĻļāĻ্āϤি āϏাāĻļ্āϰāϝ় āĻāϰুāύ, āĻāϰāĻ āϏাāĻļ্āϰāϝ় āĻāϰুāύ, āĻāĻŦিāώ্āϝ⧠āĻŦাঁāĻাāύ | Save Energy, Save Cost, Save the Future" — āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻĒ্āϰāϝুāĻ্āϤি āϏেāĻ āĻĒāĻĨেāϰāĻ āϏূāĻāύা | Heat Exchanger technology is the beginning of that path.
āĻাāĻāϏাāϰ āĻāĻšāĻŽেāĻĻ āϏāĻীāĻŦ
āĻĄেāύিāĻŽ āĻĄ্āϰাāĻ āĻĒ্āϰāϏেāϏ āĻāĻ্āϏāĻĒাāϰ্āĻ āĻ āϰিāϏাāϰ্āĻাāϰ
(Denim Dry Process Expert & Researcher)
đ§ž FAQ: āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦ্āϝāĻŦāĻšাāϰে āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āύিā§ে āϏাāϧাāϰāĻŖ āĻĒ্āϰāĻļ্āύোāϤ্āϤāϰ
1️⃣ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻী? (What is a Heat Exchanger?)
āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻāĻāĻি āϝāύ্āϤ্āϰ āϝা āĻāϰāĻŽ āĻĒাāύিāϰ āϤাāĻĒāĻļāĻ্āϤি āĻŦ্āϝāĻŦāĻšাāϰ āĻāϰে āĻ াāύ্āĻĄা āĻĒাāύিāĻে āĻĒ্āϰি-āĻšিāĻ āĻāϰে, āĻĢāϞে āύāϤুāύ āĻāϰে āĻĒাāύি āĻāϰāĻŽ āĻāϰāϤে āĻāĻŽ āĻ্āϝাāϏ āĻŦা āĻŦিāĻĻ্āϝুā§ āϞাāĻে।
A heat exchanger is a device that transfers heat from hot wastewater to cold incoming water, reducing the need for extra heating energy.
2️⃣ āĻĄেāύিāĻŽ āĻā§াāĻļিং āĻĢ্āϝাāĻ্āĻāϰিāϤে āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻেāύ āĻĻāϰāĻাāϰ? (Why is a Heat Exchanger Needed in Denim Washing Factories?)
āĻā§াāĻļিং āĻĒ্āϰāĻ্āϰিā§াā§ āĻĒ্āϰāĻুāϰ āĻāϰāĻŽ āĻĒাāύি āĻŦ্āϝāĻŦāĻšৃāϤ āĻšā§। āĻĒ্āϰāϤিāĻŦাāϰ āĻĒাāύি āĻāϰāĻŽ āĻāϰāϤে āĻĒ্āϰāĻুāϰ āĻ্āϝাāϏ āĻāϰāĻ āĻšā§। āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻĒুāϰāύো āĻāϰāĻŽ āĻĒাāύিāϰ āϤাāĻĒ āĻĒুāύāϰাā§ āĻŦ্āϝāĻŦāĻšাāϰ āĻāϰে āĻāĻ āĻāϰāĻ ā§§ā§Ģ–⧍ā§Ļ% āĻĒāϰ্āϝāύ্āϤ āĻāĻŽাāϤে āϏাāĻšাāϝ্āϝ āĻāϰে।
In denim washing, a large amount of hot water is used. Heating this water requires high gas consumption. A heat exchanger reuses heat from wastewater, saving 15–20% of gas.
3️⃣ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦ্āϝāĻŦāĻšাāϰেāϰ āĻāϰ্āĻĨিāĻ āϞাāĻ āĻী? (What are the Financial Benefits of Using a Heat Exchanger?)
āĻ্āϝাāϏ āĻāϰāĻ ā§§ā§Ģ–⧍ā§Ļ% āĻĒāϰ্āϝāύ্āϤ āĻāĻŽāϞে āĻŽাāϏিāĻ āĻā§āĻĒাāĻĻāύ āĻŦ্āϝ⧠āĻāĻŽে āϝাā§। āĻĻীāϰ্āĻāĻŽেā§াāĻĻে āĻāĻি āĻāĻāĻি āϏ্āĻĨাā§ী āĻāϰāĻ āϏাāĻļ্āϰā§েāϰ āĻāĻĒাā§, āϝা āĻŦāĻāϰে āϞাāĻ āĻাāĻা āĻĒāϰ্āϝāύ্āϤ āϏেāĻ āĻāϰāϤে āĻĒাāϰে।
By reducing gas use by 15–20%, operational costs drop significantly. Over time, this leads to major yearly savings, often amounting to hundreds of thousands of Taka.
4️⃣ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻŦāϏাāύোāϰ āĻāύ্āϝ āĻী āĻāύāĻĢ্āϰাāϏ্āĻ্āϰাāĻāĻাāϰ āĻĻāϰāĻাāϰ? (What Infrastructure is Needed to Install a Heat Exchanger?)
āĻāĻāĻি āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻāύāϏ্āĻāϞ āĻāϰāϤে āĻāϰāĻŽ āĻĒাāύিāϰ āĻāĻāĻāϞেāĻ āĻ āĻ াāύ্āĻĄা āĻĒাāύিāϰ āĻāύāϞেāĻ āϞাāĻāύে āϏংāϝোāĻ āĻĻāϰāĻাāϰ। āĻāĻাā§া, āĻāύāϏ্āĻāϞেāĻļāύেāϰ āĻāύ্āϝ āĻĒāϰ্āϝাāĻĒ্āϤ āĻাā§āĻা āĻ āĻāĻāĻি āϏāĻ িāĻ āĻĒাāĻāĻĒিং āϏিāϏ্āĻেāĻŽ āĻĒ্āϰā§োāĻāύ।
To install a heat exchanger, you need proper piping between the hot water outlet and cold inlet lines, along with space for the unit and access for maintenance.
5️⃣ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰেāϰ āϞাāĻāĻĢāϏ্āĻĒ্āϝাāύ āĻāϤ? (What is the Average Lifespan of a Heat Exchanger?)
āϏাāϧাāϰāĻŖāϤ āĻāĻāĻি āĻāύ্āĻĄাāϏ্āĻ্āϰিā§াāϞ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰেāϰ āĻā§ু ā§Ž–ā§§ā§Ļ āĻŦāĻāϰ āĻĒāϰ্āϝāύ্āϤ āĻšā§ে āĻĨাāĻে, āϝāĻĻি āύিā§āĻŽিāϤ āϰāĻ্āώāĻŖাāĻŦেāĻ্āώāĻŖ āĻāϰা āĻšā§।
An industrial heat exchanger typically lasts 8–10 years with proper maintenance and cleaning.
6️⃣ āϰāĻ্āώāĻŖাāĻŦেāĻ্āώāĻŖ āĻāϤāĻা āĻুāϰুāϤ্āĻŦāĻĒূāϰ্āĻŖ? (How Important is Maintenance?)
āϰāĻ্āώāĻŖাāĻŦেāĻ্āώāĻŖ āĻুāĻŦāĻ āĻুāϰুāϤ্āĻŦāĻĒূāϰ্āĻŖ। āĻĒাāĻāĻĒে āϏ্āĻেāϞ āĻŦা āĻŽā§āϞা āĻāĻŽে āĻেāϞে āϤাāĻĒ āĻāĻĻাāύāĻĒ্āϰāĻĻাāύে āϏāĻŽāϏ্āϝা āĻšā§, āĻĢāϞে āĻাāϰ্āϝāĻ্āώāĻŽāϤা āĻāĻŽে āϝাā§। āύিā§āĻŽিāϤ āĻĒāϰিāώ্āĻাāϰ āϰাāĻāϞে āĻāĻি āĻĻীāϰ্āĻāϏāĻŽā§ āĻাāϞো āĻাāĻ āĻāϰে।
Maintenance is crucial. If scaling or dirt accumulates, heat transfer efficiency drops. Regular cleaning ensures optimal performance and longevity.
7️⃣ ā§Ģā§Ļā§Ļ āĻেāĻি āĻ্āϝাāĻĒাāϏিāĻিāϰ āĻāĻāύিāĻে āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āĻীāĻাāĻŦে āĻŽাāĻĒা āĻšā§? (How is Gas Saving Measured in a 500 kg Unit?)
āϏাāϧাāϰāĻŖāϤ āĻāύāϏ্āĻāϞেāĻļāύেāϰ āĻāĻে āĻ āĻĒāϰে āĻŽাāϏিāĻ āĻ্āϝাāϏ āĻŦ্āϝāĻŦāĻšাāϰ āϰেāĻāϰ্āĻĄ āĻāϰে āϤুāϞāύা āĻāϰা āĻšā§। ā§§ā§Ģ–⧍ā§Ļ% āĻāĻŽ āĻŦ্āϝāĻŦāĻšাāϰ āĻŽাāύে āĻšāϞো āĻাāϰ্āϝāĻāϰ āϏাāĻļ্āϰ⧠āύিāĻļ্āĻিāϤ āĻšā§েāĻে।
Gas savings are typically measured by comparing monthly consumption before and after installation. A 15–20% reduction confirms effective energy savings.
8️⃣ āĻāĻি āĻি āĻোāĻ āĻāĻāύিāĻেāĻ āĻাāĻ āĻāϰে? (Does it Work for Smaller Units Too?)
āĻš্āϝাঁ, āϤāĻŦে āϏাāĻļ্āϰā§েāϰ āĻšাāϰ āĻāĻāύিāĻেāϰ āĻāĻাāϰ āĻ āĻā§āĻĒাāĻĻāύ āϏ্āĻেāϞেāϰ āĻāĻĒāϰ āύিāϰ্āĻāϰ āĻāϰে। āĻোāĻ āĻāĻāύিāĻেāĻ ā§Ž–⧧⧍% āĻĒāϰ্āϝāύ্āϤ āĻ্āϝাāϏ āϏাāĻļ্āϰ⧠āϏāĻŽ্āĻāĻŦ।
Yes, it works for smaller units too, though the saving percentage (8–12%) may vary depending on production scale and water usage.
9️⃣ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻāύāϏ্āĻāϞেāĻļāύেāϰ āĻāύুāĻŽাāύিāĻ āĻāϰāĻ āĻāϤ? (What is the Approximate Installation Cost?)
āĻāĻāĻি ā§Ģā§Ļā§Ļ āĻেāĻি āĻāĻāύিāĻেāϰ āĻāύ্āϝ āĻাāϞো āĻŽাāύেāϰ āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻāύāϏ্āĻāϞ āĻāϰāϤে āĻāύুāĻŽাāύিāĻ ā§Š–ā§Ģ āϞাāĻ āĻাāĻা āĻĒāϰ্āϝāύ্āϤ āĻāϰāĻ āĻšāϤে āĻĒাāϰে। āϤāĻŦে āĻāĻি āĻāĻ āĻŦāĻāϰেāϰ āĻŽāϧ্āϝেāĻ āĻāϰāĻ āĻĒুāώিā§ে āĻĻিāϤে āϏāĻ্āώāĻŽ।
For a 500 kg washing unit, installation costs range between BDT 300,000–500,000, but the investment usually pays off within a year through gas savings.
1️⃣0️⃣ āĻĒāϰিāĻŦেāĻļāĻāϤ āϏুāĻŦিāϧা āĻী? (What are the Environmental Benefits?)
āĻ্āϝাāϏ āĻāĻŽ āĻŦ্āϝāĻŦāĻšাāϰ āĻŽাāύে āĻāĻŽ āĻাāϰ্āĻŦāύ āύিāϰ্āĻāĻŽāύ। āĻĢāϞে āĻāĻি āĻĒāϰিāĻŦেāĻļāĻŦাāύ্āϧāĻŦ āϏāĻŽাāϧাāύ āĻāĻŦং āĻেāĻāϏāĻ āĻā§āĻĒাāĻĻāύ āĻĒ্āϰāĻ্āϰিā§াāϰ āĻāĻāĻি āĻ
ংāĻļ।
Lower gas consumption means reduced carbon emissions, making the process eco-friendly and contributing to sustainable production goals.
āĻšিāĻ āĻāĻ্āϏāĻেāĻ্āĻাāϰ āĻļুāϧু āĻ্āϝাāϏ āϏাāĻļ্āϰā§āĻ āύā§, āĻŦāϰং āĻĒāϰিāĻŦেāĻļāĻŦাāύ্āϧāĻŦ, āĻĻীāϰ্āĻāĻŽেā§াāĻĻি āϏেāĻিংāϏ āĻ āĻā§āĻĒাāĻĻāύ āĻĻāĻ্āώāϤা āĻŦৃāĻĻ্āϧিāϰ āĻāĻāĻি āĻাāϰ্āϝāĻāϰ āĻĒāĻĻ্āϧāϤি।
A well-maintained heat exchanger ensures consistent efficiency, cost savings, and sustainable industrial performance.

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