With sustainability issues at the forefront of public thought, many boxmakers are considering how to contribute to “2050 carbon-neutral” and other sustainable development goals. Yet in a capital-intensive industry, plants need a variety of effective solutions—without heavy investments or large instruments.
A boxplant running a single/double facer corrugator machine was operating 21 hours per day, five days a week. Its boiler operating time (flue tube boiler) was at 4,410 pounds/hour × 4 units, using liquified nitrogen gas (LNG) as fuel. The plant’s boiler fuel cost was US$600,000 per year.
The plant decided to trial a product from Kurita, a Japanese provider of water treatment chemicals intended to prevent problems in boilers and cooling water systems in industrial manufacturing. The company has experience in improving production efficiency of the manufacturing processes in petrochemicals, steel, pulp and paper, and other industries. They also remove harmful substances from wastewater and offer efficient reclamation and recycling to minimize environmental impact.
Fig. 1. The method for adding the product trialed (P) to the process
The trial used Kurita’s Dropwise Technology, which is designed to improve productivity and boosts heat transfer efficiency in industrial systems and heat exchangers. The product is dosed continuously into the steam line in front of the target device, creating a water repellent film on the surfaces. Increasing the water repellency greatly improves heat transfer efficiency, which helps to optimize productivity. At the same time, steam consumption is reduced, which leads to lower fuel consumption and reduced costs for water and energy.
The objective of the trial was to confirm the effect of the technology—especially reduction of start-up time of the corrugator machine, steam pressure/fuel consumption in the boiler, and CO2 emission.
METHOD AND RESULTS
Working with Kurita, the corrugated plant crew applied Dropwise Technology to the corrugator machine hoping to improve the heat transfer coefficient of steam with only the chemical injection (Fig. 1). Dropwise was injected into the steam line to form a water repellent film on the steam side surface of heat transfer. Dropwise covers the entire surface with a water repellent film, preventing water from forming an isolating layer.
The trial confirmed significant improvement of heat transfer efficiency leading to reduced steam consumption, less CO2 emission, and increased productivity. Fuel consumption was reduced even more than predicted (Fig. 2). Results included the following:
- The start-up time of the corrugator machine was reduced by half. Average reduction of start-up time on weekdays was 15-30 minutes; at the beginning of the week, start-up time was reduced by between 30-60 minutes.
- The boiler steam pressure was reduced. Measured boiler steam pressure dropped from 188 psig to 178 psi.
- There was a reduction of the corrugator machine’s boiler fuel consumption. Average reduction rate was 8 percent.
- CO2 emission at the plant was reduced by 551,000 pounds of CO2 per year.
The Agency of Natural Resources at the Energy Conservation Center, Japan, awarded Kurita the 2019 Energy Conservation Grand Prize in the Product and Business Model category for the improved heat transfer efficiency made possible through Kurita’s Dropwise Condensation Technology. The company will launch Dropwise in the US through Kurita America.