- Solution for calcium carbide furnace exhaust gas analysis
- Galvanizing furnace gas analysis solution
- Gas analysis solution of carburizing furnace heating furnace
Calcium carbide (CaC2) is a basic organic chemical raw material, and was once known as the mother of organic synthesis. The acetylene gas produced by it can replace petroleum products to produce a series of thousands of organic gas raw materials such as acetic acid, vinyl acetate, polyvinyl chloride, polyvinyl alcohol, and acetylene carbon ink. As a branch of coal chemical industry, calcium carbide chemical industry, on the one hand, is a vital industry, and on the other hand, it is a high energy-consuming and high-polluting industry. In the production of calcium carbide, the flue gas emitted from the calcium carbide furnace is the largest source of pollution. In order to strengthen environmental protection governance and achieve energy recycling, reduce production costs, and improve corporate and social benefits, in accordance with the National Development and Reform Commission's 2007 document 70 "Access Conditions for Calcium Carbide Industry" (revised in 2007). Newly built calcium carbide furnaces must meet the following 4 requirements: (1) construction of large closed calcium carbide furnaces; (2) single furnace capacity of 25,000KVA or more; (3) initial total capacity of 100,000KVA; (4) calcium carbide furnace gas must be comprehensively utilized.
The purification and utilization of calcium carbide furnace gas are difficult at home and abroad. To fully, safely and effectively use calcium carbide furnace gas, it is necessary to effectively monitor the calcium carbide furnace exhaust gas. There are three main analysis methods for calcium carbide furnace exhaust gas: manual (Australian gas analyzer) analysis, chromatograph analysis, and online analysis. Shandong Xinze Instrument Co., Ltd. specializes in the production of closed-line calcium carbide furnace gas online monitoring system. It has unique design for the analysis system of calcium carbide furnace exhaust gas. Through the analysis of the preparation of exhaust gas, the new calcium carbide furnace and the old calcium carbide furnace are transformed. The exhaust gas is fully utilized, thereby achieving environmental protection, labor protection and energy recycling, reducing production costs, and improving corporate and socio-economic benefits.
█ Characteristics of calcium carbide furnace exhaust
In the sealed calcium carbide furnace in the production process, the main reaction formula for generating the product after being energized is shown in (1):
CaO + 3C = CaC2 + CO
a, Furnace gas capacity: 400Nm3 / t calcium carbide;
温度：正常400--800℃，（瞬时）1000℃。 b. Temperature: Normal 400-800 ℃, (instantaneous) 1000 ℃.
炉气的组分（一般） c. Components of furnace gas (general)
d 、 Dust content and composition
Dust content: 50-150 g / Nm3
█ Characteristics of calcium carbide furnace exhaust
The characteristics of the closed calcium carbide furnace exhaust gas are as follows:
a. The temperature of the calcium carbide furnace exhaust gas is high and unstable;
b. The furnace gas volume fluctuates steadily. The carbon monoxide concentration in the tail gas is high, which is about 74-85%, and the temperature is high.
For flammable and explosive gases;
c. Exhaust dust content is large and particle size is small, about 5 to 10 μm accounts for about 40% of the dust, less than 11% above 40 μm,
The dust up to 150g / Nm3 makes the exhaust gas recovery very unfavorable;
d. The exhaust gas has a certain heating value of about 2300-2600 Kcal / Nm3;
e. The tail gas contains a small amount of tar, which sticks to the dust after precipitation, which brings inconvenience to low-temperature dust removal.
█ Closed calcium carbide furnace exhaust gas analysis system
The general analysis system can be divided into three parts from the structure, namely the sampling system, the pretreatment system, and the analysis system. According to the above characteristics of furnace gas, Shandong Xinze Instrument Co., Ltd., after years of experience accumulation, functionally divides the analysis system into several parts as shown in Figure 1. Based on this, the complete system is designed and manufactured to build a large-scale closed calcium carbide furnace (50,000 tons) and the transformation of the old calcium carbide furnace have achieved good results.
The design of the analysis system is briefly introduced below.
a. Selection of sampling points
The selection of sampling points should meet the following requirements: can truly and timely reflect the parameters of the furnace conditions that the user is concerned about; the temperature, pressure and flow of the sampling points are relatively stable; the amount of dust and tar is as small as possible. If the sampling point is not selected properly, it will bring additional burden to the subsequent system and may not even truly reflect the required furnace condition parameters.
b. Design of sampling system
The sampling system is the first pass of the entire analysis system. Whether it is successful will directly lead to the success of the entire analysis system. The temperature of the sampling point of the calcium carbide furnace exhaust gas is about 200-300 ℃, and the relative pressure is between slightly positive pressure and slight negative pressure. Due to the special nature of the furnace gas, the sampling system must have a preliminary physical separation of the sample components, and the sampling The solid particles around the probe are separated from the gaseous fluid, so the sampling system must not only have a probe (sampling tube), but also a filtering system, a probe cleaning system, etc. In addition, it should have a structure that is easy to maintain. m 粉尘的99%滤出。 The SP1100 sampling probe independently developed by Shandong Xinze Instrument Co., Ltd. can filter out 99% of dust larger than 0.3μm . The SP1100 sampling probe, coupled with a program-controlled automatic purging device, can take on this task.
c. Design of pretreatment system
The pretreatment system mainly completes the safe, timely, and effective processing of the gas samples delivered from the sampling system to meet the operating conditions of the instrument analysis system. First, the design of the transmission pipeline must meet the aerodynamic requirements to make the sample gas flow path unobstructed. Next, the sample gas is subjected to a series of conventional treatments such as dust removal, tar removal, pressure adjustment, water removal, and steady flow. Dry and clean the processed sample gas so that the key components entering the instrument analysis system can be accurately analyzed. So as to provide scientific basis for the production safety of calcium carbide and the effective use of furnace gas.
The dust removal system includes filtration, cleaning, re-filtration, etc. to prevent pipeline blockage; the decoking and oil removal system includes temperature control, washing out, adsorption, etc., which is conducive to the smooth flow of pipelines and protects analysis equipment; Mist capture, gas-water separation, drying filtration, etc., protect the analyzer to ensure accurate testing; the pressure adjustment system includes pumps, regulating valves, fast circuits, etc. to ensure the normal working conditions of the instrument. Programmable control (PLC) system, mainly including PLC, program software, actuator, human-machine interface, etc., is mainly used to implement automatic control of the sampling pretreatment system, and alarm when abnormal conditions occur.
d. Instrument analysis system
The system includes a flow adjustment device, an anti-abnormal water inlet device, a calibration device, and an analytical instrument. The analytical instruments are configured according to the calcium carbide production process and the use of exhaust gas. Generally, O2, H2, CO and other gases in the exhaust gas of the sealed calcium carbide furnace are mandatory items. The contents of O2 and H2 are safety indicators, and CO is the core of exhaust gas utilization. 。 For the determination of O2, select the S1000 series; for the determination of H2, select the S3000 series; for the determination of CO, select the S2000 series . For places where CH4 and CO2 need to be measured, the SIC-100 multi-component analyzer can be selected.
█ Application of kiln exhaust gas
Based on the functional block diagram shown in the figure, the TK-3000 series calcium carbide furnace exhaust gas analysis system manufactured by Xinze Company will also be targeted for design according to the working conditions and requirements of different users.
In short, the closed type calcium carbide furnace is suitable for large-capacity furnaces. The furnace gas can be comprehensively used after being extracted from the furnace, which not only reduces the energy consumption of smelting, but also reduces the huge waste of energy. At the same time, direct emissions of flue gas are greatly reduced. Conducive to environmental protection. It is in line with relevant national industrial policies and will surely develop rapidly. At the same time, there will be increasingly higher requirements for its online exhaust gas analysis system. Therefore, the calcium carbide furnace exhaust gas analysis system should put forward higher requirements in terms of advancedness, applicability, reliability, stability, and safety.