From waste to resource: how an Asian rubber manufacturing plant reclaimed hot and cold water for free

The challenge

Petrochemical plants, particularly those involved in the production of styrene butadiene rubber, consume vast amounts of energy. Distillation and stripping columns are among the most energy-intensive units, often treating heat in top vapors or gases as waste. The challenge for the Asian rubber producer was to find a way to recover this waste heat and reuse it within the plant, thereby reducing energy costs and improving efficiency.

Our solution

Alfa Laval provided the perfect solution with their compact heat exchangers, known for their high thermal efficiency and ability to operate with crossing temperatures in a single unit. The plant installed two spiral heat exchangers and one Compabloc to recover heat from the stripping overhead process gas, which has a temperature of about 100°C (212°F). This recovered heat was then utilized in two stages: a hot water loop and an absorption chiller system.

Process implementation

The implementation process involved two key stages:

1. Hot water loop: The first stage of heat recovery used the hot gas to heat the loop return water from 75°C (167°F) to 85°C (185°F) via an Alfa Laval Compabloc. Previously, this water was heated using steam throttled down from 10 to 2 bar. By using recovered heat instead, the plant saved steam worth approximately €500,000 per year.
2. Generating chilled water: In the second stage, the gas passed through two Alfa Laval spiral heat exchangers installed in parallel. The recovered heat was used to produce chilled water in an absorption chiller, replacing the traditional ammonia system. This revamp, completed in 2008, reduced the plant's electricity consumption by 50 kWh per produced ton of butadiene rubber, resulting in annual electricity savings of €160,000.

Heat recovered from a stripping column is used for producing chilled water in an absorption chiller system and for heating the water in a hot water loop serving various heat exchangers throughout the plant. The revamp resulted in a total annual energy saving of about 660,000 euros.

Impact and benefits

The installation of Alfa Laval's heat exchangers brought substantial benefits to the styrene butadiene rubber plant:

• Energy savings: The plant achieved total annual energy savings of approximately €660,000.
• Efficiency: The high thermal efficiency of the compact heat exchangers allowed for maximum heat recovery with minimal floor space.
• Cost reduction: The plant significantly reduced its steam and electricity consumption, leading to lower operating costs.
• Sustainability: By recovering and reusing waste heat, the plant improved its overall energy efficiency and sustainability.

Alfa Laval's innovative heat recovery solutions have proven to be a game-changer for the styrene butadiene rubber producer, enhancing profitability and sustainability in a challenging business environment.