Promoting Low Carbon Technology and Energy-saving in Semiconductors Manufacturing Process Using Electrolyzed Water

SHINRYO CORPORATION

Photo.1: Pleated media inside Electrolyzed Water Air Washer System

Fig.1: Differences in structure of conventional external air conditioner unit and unit with Electrolyzed Water Air Washer System installed

Outline

Shinryo Corporation has developed and commercialized a high-performance, environmentally friendly Electrolyzed Water Air Washer System. We are currently at the stage of promoting the system with the aim of adoption in all outdoor air handling units in Japan and overseas, to contribute to the reduction of CO2.

Precision products such as semiconductors and liquid crystals are manufactured in high-precision clean rooms that remove not only dust from the air but also trace gaseous contaminants contained in outdoor air. In recent years, both air washers and special-purpose chemical filters (CFs) for gas removal have been increasingly installed in the outdoor air handling units of clean rooms.

The Electrolyzed Water Air Washer System can remove gaseous contaminants with high efficiency, using only an air washer that uses electrolyzed water without a CF. This can significantly reduce energy consumption by 24% and CO2 emissions by 15% compared with the installation of CFs, conserving energy and lowering carbon emissions. In addition, it generates almost none of the industrial waste associated with CF replacement.

Description

In the manufacturing environment for precision products such as semiconductors and liquid crystals, dust contained in air and trace gaseous contaminants contained in outdoor air affect the product yield. In recent years, air washers and special-purpose chemical filters (CFs) to remove dust and gaseous contaminants have been increasingly installed in outdoor air handling units. However, CFs exhibit the following weaknesses (1) to (5).
(1) Acetic acid is emitted when organic esters are adsorbed by CFs, and nitrate ion and nitrite ion are emitted when NOx is adsorbed, making CFs sources of contamination in clean rooms.
(2) External air conditioner units must be stopped operation during CF replacement, complicating clean room operation and maintenance.
(3) Maintaining the removal performance of CFs requires reducing the relative humidity of CF inlet air. For this reason, a mechanism for constantly raising inlet air temperature must be installed, increasing energy consumption.
(4) The activated carbon in CFs must be replaced every year or several years, generating activated carbon as industrial waste. The weight of the activated carbon generated by an external air conditioner unit with 100,000m3/h-class blowing capacity is 1 to 2 tons by replacement every year or several years.
(5) CF replacement involves costs.

The Electrolyzed Water Air Washer System can remove gaseous contaminants with high efficiency, using only an air washer that uses electrolyzed water without a CF. We have developed a mechanism that improves the gas-liquid contact efficiency with electrolyzed water, using pleated media (developed by Shinryo Corporation; Patent No. 5137878) and using electrolyzed water as the air washer absorbing solution, in a system that can remove acidic gases in particular with high efficiency. In addition, we have developed and implemented a control mechanism that detects fluctuations of acid gas concentration in outdoor air and supplies an optimal flow rate of electrolyzed water.

Feature (1) Demonstrates high removal performance without using CFs
The Electrolyzed Water Air Washer System demonstrates sulfate ion (SO4 2-) removal efficiency at a high level of 99% or more (Table 1). It can also remove ammonium ions (NH 4+). The system also offers the advantage of not requiring CFs, thus eliminating the nitric ion and acetic ion emitted by CFs.

Feature (2) 24% reduction in energy consumption, 15% reduction in CO2 emissions, 30% reduction in running cost
As the Electrolyzed Water Air Washer System does not require a reheating mechanism as is conventionally required to maintain removal performance in CFs. It also enables optimal operation of the system through a control mechanism (developed by Shinryo Corporation). As a result, it is able to significantly reduce energy consumption in the external air conditioner unit overall by 24%, CO2 emissions by 15%, and running cost by 30% (compared to our earlier model).

Feature (3) A zero-industrial-waste, environmentally friendly system
The Electrolyzed Water Air Washer System does not need CFs and thus does not require the exchange or disposal of activated carbon, making it an environmentally friendly system that can cut industrial waste to zero.

We are currently at the stage of promoting the Electrolyzed Water Air Washer System with the aim of adoption in all outdoor air handling units in Japan and overseas. The system can significantly reduce energy consumption by 24% and CO2 emissions by 15% compared with the installation of CFs, conserving energy and lowering carbon emissions. In addition, it generates almost none of the industrial waste associated with CF replacement. By making the system widespread, we will work to reduce CO2 emissions in the industrial sector.