How should a distillation tower be adjusted at the beginning of operation to function properly?
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Is the adjustment process of the distillation tower at the beginning of operation as follows: 1) Fill the distillation tower with nitrogen (if it is not a vacuum tower, it is necessary to avoid excessive pressure due to rising temperature); 2) Establish a liquid level in the bottom of the tower (this liquid is a mixture of light and heavy components, which should be prepared in advance if needed); 3) Start the pump at the bottom of the tower to create circulation within it. The feed rate and the amount of liquid sent out from the bottom of the tower can be determined based on whether the liquid level there rises. If possible, the liquid from the bottom of the tower should be sent back to the feed tank or feeding should be temporarily stopped; 4) Supply steam to the reboiler at the bottom of the tower, allowing its temperature to rise to normal levels. It is important to control the pressure in the tower to prevent the safety valve from activating due to high pressure. Feed should be added appropriately based on the liquid level in the bottom of the tower, to avoid too low a level. At the same time, the rate of temperature increase must be carefully controlled to prevent damage to the reboiler due to thermal stress; 5) Once the liquid level in the tank containing the light components at the top of the tower exceeds 50%, start the pump at the top of the tower and use full reflux to adjust the temperature there to normal levels. If the liquid level in that tank is not high, there is no need to send any liquid out; if it is possible, it can be sent to the feed tank; 6) Stabilize the pressure inside the tower as well as the temperatures at the top and bottom of the tower. After about half an hour, arrange for sampling by Sinochem for analysis; 7) Once the analysis shows satisfactory results, connect the systems connected to the outlets at the top and bottom of the tower. 8) Gradually increase the feed rate, adjust the reflux at the top of the tower and the steam supply at the bottom of the tower, in order to stabilize the pressure inside the tower until the system reaches its normal operating conditions. (At this stage, the reflux at the top of the tower and the steam supply at the bottom of the tower can be automated, as long as the feed rate is not changed too quickly.) Are there any issues with the above adjustments? Please provide some guidance
No extra points needed; experts, could you help check if there are any issues?
There are many types of distillation towers, depending on the medium being processed. Since it’s unclear what your medium is and what the operating conditions are, it’s impossible to determine the appropriate type. The basic principles for large distillation towers remain the same; there are several key points to consider: preventing overheating and overpressure, establishing circulation for the feed material, ventilation, and cooling medium, as well as using full reflux ； After the sampling meets the requirements, extraction, liquid discharge, and feeding begin
It is a methanol dehydration tower; the temperature at the top of the tower is 64.5 degrees, while it is 106.2 degrees at the bottom. The pressure is slightly positive. The light components at the top of the tower are sent to the methanol storage tank, whereas the wastewater from the bottom of the tower is sent for wastewater treatment.
I have worked on low-temperature methanol washing units for the pre-washing and dehydration of methanol; 5 cubic meters of pre-washed methanol per hour, along with additional methanol, are used to process approximately 10 cubic meters of feed material per hour. For driving the process, maintain a pressure control of 0.1–0.15 Mpa; if the liquid level is at 70%, more liquid needs to be added. The steam pressure should be around 3000, and the volume of circulating water seems to be 900 cubic meters. Full reflux is used, with the temperature at the bottom of the tower ranging from 110–120°C, and the temperature at the top of the tower around 60–70°C. The temperature of the reflux liquid should be around 40°C. It’s important that fluctuations in each of these parameters remain within acceptable limits, as adjustments take time to take effect; stable empirical values will help achieve stability over time. If sampling is taken after 4 hours, both the top and bottom of the tower will generally meet the requirements
Feed rate and output from the tower bottom Feed rate and output from the tower bottom
This post was last edited by czg1101 on 2015-8-10 at 12:54. Thank you:P; it’s very similar to what I thought. I used to work in ammonia synthesis and am familiar with the principles of distillation, but I haven’t had much experience with its application in practice. The wastewater separation process using four towers in the methanol distillation process in the methanol plant is quite similar to ours. I’ll ask them about it tonight.
What does lag mean? When adjusting the steam at the bottom of the tower, is there a significant lag in the temperature there? How long does this lag last? We need to consider the amount and frequency of steam adjustment during startup, the appropriate percentage of steam added in the initial stage, as well as the amount and frequency of additions thereafter. In other words, how much steam should be added each time, how often it should be added, and what the rate of increase in the bottom-of-tower temperature should be! (These are the key points.) As for the top-of-tower temperature, there is no plan to control it specifically; once the liquid level in the light component storage tank is normal, full reflux will be used, and if possible, the temperature will be adjusted to normal levels. Regarding the purity of the light and heavy components, there is no expectation that they will reach acceptable levels quickly; it should take some time for these parameters to normalize once the temperature, pressure, and reflux levels in the tower are within normal ranges.
Our feed volume is normally around 110 cubic meters; the output from the top of the tower is 33 tons. The volume at the bottom of the tower seems to be between 70 and 80 cubic meters, and the steam generated there is approximately 60 tons, at a pressure of 0.8 Mpag.