4 System Composition
7
FOCUSED PHOTONICS INC
gases such as SO
2
, NO
X
and O
2
. The measurement of gases like HCl, HF and CH
4
requires
utilization of LGA-4100 semi-conductor laser gas analysis meter.
The stack dust monitoring sub-system uses LDM-100 laser dust meter to measure the density
of dust in the stack gas by laser transmission method.
Gas parameter monitoring sub-system includes the measurement of the flow rate, pressure
and temperature of gas. The differential pressure transmitter measures the total pressure and static
pressure in the gas flow and converts them to be the flow rate of the gas while the PT sensor
measures the temperature of the gas.
The data acquisition and processing sub-system is composed of electric control unit, IPC and
the enterprise DCS interface module. The electric control unit receives the signal output from all
devices and supplies the power for them. Its internal processing unit converts the data to industrial
standard RS485 protocol with (4-20)mA power. The monitoring software on IPC summarizes all
the gas density information and working status information. It has functions such as report
creation, data storage, history data searching and network communication with environmental
protection authorities.
4.1
Gaseous Pollutants Monitoring Sub-System
The gaseous pollutants monitoring sub-system adopts the special technology of hot humidity
method (owned national patent). The principle is the system measures the SO
2
and NO
X
(including
water) in the hot and wet gas by ultraviolet difference method and measures the oxygen content by
ZrO
2
and then calculates the dry gas density by the dry and wet conversion.
4.1.1
Sampling Pre-Processing System
The pre-processing system of CEMS-2000 System is composed of parts like temperature
sensor, high temperature measuring room, jet injector and ZrO
2
measuring module.
The CEMS-2000 pre-processing system works as Fig 4-3. The stack gas goes through the
high temperature sampling probe and tracing pipe to enter the gas measuring tank (high
temperature gas chamber). The measuring pool is put in the heating cabinet to keep the gas in high
temperature during the sampling process. Thus no condensing water will be extracted and no
water-soluble gas like SO
2
and NO
2
will be lost. Also the equipment will not be corroded by acid
liquid and the accuracy of measurement result will be guaranteed. The sampling probe, tracing
pipe and heating cabinet can be set at different temperature by OMA-2000 spectroscopic gas
analyzer. After the whole measurement is finished, the stack gas will be evacuated from the
exhaust pipe. The whole pre-processing sampling is performed by the high reliable jet injector
which has no mechanical movement parts and with high reliability.
