By-product steam from the two-in-one furnace

Our factory is constructing a 6Wt HCl 2-in-1 graphite synthesis furnace, which generates 3–4 kilograms of steam as a by-product. This by-product can be utilized effectively to make use of thermal energy. In any case, the HCl produced needs to be cooled due to its high temperature. Last edited by limingshuguang on 2007-11-29 at 11:22

Currently, all domestic two-in-one furnaces are capable of producing hot water or steam as by-products. Most domestic manufacturers produce hot water as a by-product, while some produce steam (such as Hunan Zhuzhou Chemical Plant, Tianjin Dagu Chemical Plant, Yangnong Chemical, Shaanxi Jintai, etc.). The main difference between these two forms is as follows: By-product steam: It requires high-standard equipment; the synthesis furnace functions as a pressure vessel, which makes it more complicated to use, obtain certifications, and conduct inspections in the future. The materials used for the equipment itself as well as the manufacturing requirements are stringent, resulting in higher costs. However, the by-produced steam has a high utilization rate, especially in lithium bromide refrigeration systems. By-product hot water: The equipment requirements are relatively low, and it is not used as a pressure vessel. The utilization rate of the by-produced hot water is relatively low, and it may sometimes not be sufficient to meet the production requirements of lithium bromide units. If a conventional circulating cooling water system is used to cool the synthesis furnace, significant heat energy is wasted. This post was last edited by yhpsxj on 2007-11-29 12:41.]

From an equipment and technology perspective, the steam and hot water generated by synthesis furnaces in China are currently sufficient to meet the needs; it mainly depends on whether the by-products have any useful applications – manufacturers who don’t need hot water, for example, won’t require it

2# Speaking of by-product steam at 3-4kg/cm2? Are you using the furnace from that manufacturer? Here, the pressure of the by-product steam is generally kept below 2.5 kg/cm2, while the setting pressure of the safety valve is 3 kg/cm2. Its performance is decent; it saves energy, and the steam generated as a by-product can be used for heating brine, lithium bromide, or vaporizing liquid chlorine. For a furnace with an inner diameter of 1000 mm, proper insulation measures can result in a by-product steam output of over 1.5 t/h. It offers significant energy savings compared to traditional hot water boilers, and it also features automatic ignition sowie the advantage of not requiring a jet pump during normal operation. Of course, there are also disadvantages, such as issues with the level control of the jacket water, sealing problems, and so on.

Reply to 5#: Our factory is still under construction. The steam pressure of 3–4 kg/cm2 I mentioned was specified by the design institute; the furnace is still under evaluation```

The design institute we worked with designed for us a hydrochloric acid synthesis furnace that generates 6 kg/cm2 of steam as a by-product. The inner wall of this furnace is coated with resin for corrosion protection, but I believe such a furnace is not very reliable, as the anti-corrosion coating on the inner wall tends to peel off easily. I’m not sure how it’s done in your areas; I’d appreciate some guidance.

Energy conservation and environmental protection will be the main theme in the future!

Currently, the auxiliary steam boilers are supplied by Nantong Xingqiu; the users include Yangnong (for 2 years), Nantong Jiangshan (for 9 months), Dagu, Tianye, etc. (the usage status for these last ones cannot be confirmed with certainty, but the first two companies are indeed using them, and I work for one of them). If you are interested, we can discuss options, design details, and usage experiences

Since you’re here, please ask your friend to explain the situation.

Generally speaking, the main difference between a by-product steam hydrochloric acid furnace and a regular hot water furnace lies in the furnace body; the subsequent cooler, primary and secondary absorbers, as well as the exhaust gas absorption system, are all the same. The jet pump is used only during startup and shutdown； The furnace body consists of a graphite jacket; the continuously supplied high-purity water absorbs the heat generated by chemical reactions, resulting in phase transformation into low-pressure steam. It is necessary to establish an independent steam network for this by-product steam. The pressure of this by-product steam does not remain very high (currently it is around 2.5 kg/cm2, depending on the production load), due to limitations imposed by the graphite components (which can generally withstand pressures of up to 4 kg/cm2). Additionally, because the water content is high, the steam pipes need to have valves that prevent water accumulation, and these valves should be more sensitive than those used in saturated steam systems. Each furnace unit should be equipped with a control valve set at the outlet for the by-product steam, and it is advisable to install automatic venting devices at the end of the steam network, so that it can be connected to the original saturated steam system before being used by heating equipment. The utilization of the by-product steam can be determined based on the specific conditions of the manufacturer; we currently use it for preheating saltwater. With a diameter of d1000 mm, it is capable of producing 1.6 tons of steam per hour at full load (estimated value, which is mainly related to heat losses). The liquid level of the jacket water must be properly controlled, as there are two circular openings at the top of the furnace (in my furnace). Hot water circulates in a radial direction, while hydrogen chloride gas moves axially; if the water level drops below those circular openings, the graphite will crack (this has already happened before). Furthermore, as the load and steam pressure change, the temperature of the hot water changes, which in turn affects its density; accordingly, the liquid level control also needs to be adjusted, especially during startup. The chlorine and hydrogen pipelines entering the furnace, the ignition system, flame detectors, etc. are modified in accordance with SGL standards to enable automatic ignition. The current lamp head design is acceptable (of course, it can’t compare to SGL), and the hydrochloric acid produced is colorless and transparent; the free chlorine level is around 10-20 (this was tested while the machine was in operation, but it’s no longer done now). Hydrogen chloride was also analyzed, with a concentration of 95.3%. The furnace pressure is 5–7 kPa (it varies depending on the load and the ratio of absorbed water to dilute acid). Special reminder: 1. Special care must be taken in the design and operation of the condensed acid discharge and collection system, as mixed explosive gases may be present. 2. The acid delivery pipeline must take into full account the issue of gas resistance, and the exhaust gas absorption section needs to consider the pressure drop, as it is directly related to the furnace pressure.

Is there anyone among you who uses by-product steam as a heat source for lithium bromide? Share some design and usage experience!