ABB SCC Gas Preprocessing System Maintenance and Selection Guide

Practical Guide for Maintenance and Selection of ABB SCC Gas Pre treatment System

In the field of modern industrial process control and environmental monitoring, the measurement accuracy and service life of gas analyzers (such as ABB's EL3000 and AO2000 series) depend not only on the performance of the analyzer itself, but also on the gas state before entering the analyzer. The sample gas directly extracted from industrial sites often contains a large amount of dust, moisture, corrosive gases, or has extremely high temperatures and pressures. If it enters the analyzer directly without effective processing, it will not only cause serious distortion of the measurement results, but also result in permanent damage to expensive optical or electrochemical sensors.

The ABB SCC (Sample Gas Conditioning) series gas pretreatment system is designed to address this pain point. As a "protective shield" connecting harsh working conditions and high-precision analyzers, the SCC system processes the sample gas to a perfect state that meets the analyzer's inlet requirements through a series of modular coolers, feed pumps, filters, converters, and control units. For on-site instrument engineers, mastering the hardware architecture, selection boundaries, and on-site maintenance specifications of SCC systems is the key to ensuring the long-term stable operation of the entire analysis system.

Analysis of Core Preprocessing Components: From Cooling to Feeding

The first priority of gas pretreatment is to control humidity (dew point). ABB provides cooling solutions at different levels.

1.1 SCC-C Compressor Style Gas Cooler

SCC-C is the main equipment for handling complex working conditions, especially suitable for high dust, high temperature or high humidity sample gas environments.

Constant dew point control: The factory set sample gas outlet temperature is+3 ° C, and the dew point stability is extremely high. When the ambient temperature changes by 10 ° C or the flow rate changes by 10 l/h, the fluctuation is only ± 0.3 ° C. This provides an extremely stable basic environment for the analyzer.

Multi material heat exchanger: To cope with gases of different corrosives, the heat exchanger is available in three materials: glass, PVDF (polyvinylidene fluoride), and stainless steel. The pressure adaptation range is extremely wide: glass material supports 50-200 kPa (absolute pressure), PVDF supports 50-250 kPa, and the stainless steel high-pressure version supports up to 1 MPa (10 bar). If a peristaltic pump is selected for drainage, the pressure range is usually limited to 50-150 kPa.

Explosion proof and safety certification: This cooler can be equipped with ATEX and CSA explosion-proof versions (applicable to Zone 2 hazardous areas), and meets the strict requirements of the German Federal Emission Control Law (17th BImSchw). It is widely used in environmental monitoring scenarios such as waste incineration or power plants.

1.2 SCC-F and SCC-S sample gas feeding units

The feeding unit is responsible for drawing the sample gas into the system at a constant flow rate.

SCC-F feeding unit: adopts a completely metal free anti-corrosion gas path design, including two independent gas path channels. Each channel is equipped with a rotor flow meter (10-100 l/h) and a needle valve, with a maximum bypass flow rate of 200 l/h. The diaphragm pump can overcome negative pressure and stably deliver the sample gas to the analyzer.

SCC-S Feed Unit: This is a 19 inch rack mounted (4U height) compact solution designed specifically for simple non corrosive gases. Its biggest highlight is the optional Peltier electronic cooler. Compared with compressor type coolers, Peltier has a smaller volume and its outlet dew point is also controlled at+3 ° C, making it particularly suitable for use with EasyLine series analyzers. It can maintain stable cooling performance even at ambient temperatures up to+50 ° C.

Sample gas conversion and common unit configuration

2.1 SCC-K Converter: Solving the Measurement Difficulty of NO2 and Complex Components

In smoke emission monitoring, NO2 is highly soluble in water at room temperature, which can cause pipeline corrosion and measurement loss. The function of SCC-K converter is to reduce NO2 to NO.

Carbon molybdenum catalytic converter: Based on carbon molybdenum catalyst, the reaction temperature ranges from 320 ° C to 360 ° C (depending on the flow rate). The effective conversion rate of the new catalyst is ≥ 95%, and its service life is usually greater than 6 months. Its advantage lies in the ability to replace catalyst filters without the need for tools, greatly reducing maintenance costs.

Quartz glass thermal converter: For more complex applications such as TRS measurement in the pulp and paper industry, H2 conversion of HCl in chlor alkali plants, and oxidation of chlorinated hydrocarbons in PVC plants, SCC-K provides quartz glass reaction tubes with a maximum working temperature of 680 ° C. This model has no consumable parts and a conversion rate of ≥ 99%, but the heating time is relatively long (about 60 minutes).

Attention: The sample gas pressure of SCC-K must be controlled within p-abs ≤ 200 kPa (catalytic type) or 120 kPa (thermal type), and the system pressure drop must be minimal to ensure smooth gas passage.