Questions about the steam heating process – seeking answers?
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This post was last edited by qun123321 on 2018-5-2 at 08:41. The superheated steam, with a pressure of 0.6 Mpa and a temperature of 280 degrees, enters the drum and then splits into three branches for heat exchange. The first branch goes to the reboiler of the distillation tower for heating (the heat exchange area of the reboiler is 200 square meters, and the temperature at the bottom of the tower is 130 degrees). The second branch goes to the internal coils of 5 storage tanks to provide heating (the heat exchange area of each internal coil is 20 square meters). The third branch goes to the reboiler of the hydrolysis tower for heating (the heat exchange area of this reboiler is 100 square meters, and the temperature at the bottom of the tower is 110 degrees). After heat exchange, these three pipelines all lead to the condensate tank. A control valve is installed on the outlet pipeline at the bottom of the condensate tank to regulate the level of steam condensate, which is then sent to other equipment that utilize hot water for heat exchange. Question 1: Is it necessary to install a steam trap at the reboiler outlet before it connects to the condensate tank? Question 2: Does flashing occur to generate secondary steam when the condensate enters the condensate tank? Question 3: Does superheated steam need to be cooled to saturated steam before being fed into the reboiler for heating? Question 4: In the second line, the superheated steam flowing through the coiled tubes in the 5 storage tanks undergoes heat exchange via 20 square meter of coiled tubes; does this process only release sensible heat, resulting in little drop in steam temperature? Since the outlet is in gaseous state, is it advisable to install a drain valve? It’s still better to connect it directly to the condensate tank, or are there any other better ways to provide heating? Question 5: After heat exchange, when the temperature of this superheated steam drops to 158 degrees while the pressure remains at 0.6 MPa, does it become saturated steam? At 0.6 Mpa, the corresponding temperature for saturated steam is 158 degrees. I hope fellow sailors can give me some advice! I am extremely grateful!
I’m not very familiar with some of the theoretical aspects, but based on actual production practices: Question 1: Is it necessary to install a steam trap at the outlet of the reboiler before it feeds into the condensate tank? A hydrophobic valve needs to be added. Question 2: Does flashing occur to generate secondary steam when the condensate enters the condensate tank? Yes, a steam vent needs to be installed on the top of this condensate tank. Question 3: Does the superheated steam need to be cooled to saturated steam before being fed into the reboiler for heating? It is best to enter the reboiler for heat exchange after temperature and pressure reduction. Question 4: In the second line, the superheated steam flowing through the coiled tubes in the 5 storage tanks undergoes heat exchange via 20 square meter of coiled tubes; does this process only release sensible heat, resulting in little drop in steam temperature? Since the outlet is in gaseous state, is it advisable to install a drain valve? It’s still better to connect it directly to the condensate tank, or are there any other better ways to provide heating? This steam requires a low amount, and it should be used for heating or insulation; it is recommended to utilize waste steam
This condensate tank is a pressure vessel equipped with a safety valve; under pressure, it uses the pressure difference to transfer the collected steam condensate to other devices that require heating by hot water, where it then goes into the hot water storage tank for use
Superheated steam is not suitable for heat exchange; it is recommended to reduce its temperature and pressure to that of saturated steam right from the source before using it. As for steam traps, steam traps designed for superheated steam are basically not hydrophobic and thus do not function.
There are quite a few issues. Let me explain my thinking: 1. \"Does superheated steam need to be cooled to saturated steam before being fed into the reboiler for heating?\" This depends on the temperature of the heat exchange medium at the bottom of the tower. In the two scenarios you mentioned, it is necessary to use a temperature reduction valve. 2. “Flash evaporation generates secondary steam”; there should be secondary steam, which requires a dedicated line for discharge. 3. I think for these situations you mentioned, it’s better to add a strainer as well.
I think it would be better to move this post to the process area for discussion.
The medium inside the distillation tower is a mixture of water, formaldehyde, and material A; material A is the product, accounting for only 10% of the mixture, while formaldehyde makes up 6%, with the remainder being water. The light components, formaldehyde and water, are obtained from the top of the distillation tower, while material A (with a boiling point of 380 degrees) is found at the bottom of the tower. Dehydration rate: 55%. The operating pressure of this tower is 0.18 Mpa. The temperature at the bottom of the tower is 130 degrees, and the temperature at the top of the tower is 125 degrees. It can be said that the medium heated by the reboiler is mostly water. In my personal understanding, superheated steam entering the reboiler first goes through a cooling process; once it reaches the saturation temperature, it begins to condense, releasing the latent heat of vaporization which is used for heating. It is necessary to increase the residence time of the superheated steam within the reboiler in order for it to reach the saturation temperature. The outlet of the reboiler is connected to a condensate tank, where the uncondensed steam can return to the system to continue heating until it condenses. From this process, the heating effect of superheated steam should be ideal.
If the steam trap for superheated steam does not provide hydrophobicity, it is probably because there is no heat exchange to reduce the temperature to the condensation level
A large temperature difference poses a challenge to heat exchanger equipment.