134- Discussion on the design and layout of the vapor-liquid separation internals for the heat exchange drum dedicated to reactors

The reactor drum serves the following main functions: 1. It provides sufficient space for the vapor-liquid phase and for reactions to take place, as well as enabling the timely addition or removal of heat from the reaction system, thereby ensuring that the reaction meets the requirements of stability, controllability, and depth specified in the process parameters. 2. Provide efficient vapor-liquid separation technologies to ensure that the steam and liquid streams delivered from the drum can be transported smoothly and stably through the external pipeline equipment of the system. This enables both stable and controllable heat exchange processes within the system, as well as stable and controllable transportation of these streams through the external pipeline equipment.

In the design of a reactor drum, the shape of the drum and its internal structure are inevitably involved. Based on the appearance of the reactor drum, they are mainly divided into two categories: drums with a separation tower head and drums without a separation tower head. As for whether a separation column head is required for the drum, it mainly depends on the type of liquid stream that the process package requires to be returned to the system inside the drum, as well as the differences in process parameters and composition. If the process package involves few types of liquid streams that need to be reinjected into the drum’s internal system, with minimal differences in process parameters and composition, then a conventional drum type is sufficient. If the process package involves a variety of liquid streams that need to be reinjected into the drum’s internal system, with significant differences in process parameters and composition, then a separation column must be installed. This allows the various reinjection streams to undergo thorough mass transfer and mixing within the separation column, resulting in a quasi-homogeneous liquid stream before it flows into the liquid collection area at the bottom of the drum.

This post was last edited by luoli519 on 2019-7-2 at 15:33. The vapor drum of the oxidation reactor in the EO/EG units of refining enterprises is a type of reactor vapor drum equipped with a separation column head. Please take a look at the image below:

This post was last edited by luoli519 on 2019-7-2 at 15:33. A reactor drum of type D-110, which features a separation column atop it, consists of a regular drum to which a separation column is added; this column includes its own tower body, support plates, distribution plates, packing, as well as various inlet and outlet pipes. I remember having discussed the reactor drum specifically on the Haichuan Chemicals forum; please check that post in detail, as there is no need to repeat it here. The following figure is a side view of the drum of the D-110 reactor:

I plan to focus on discussing and sharing here the design aspects related to vapor-liquid separation internals inside the lower horizontal vessel, which is common to reactor drums.

Thank you to the original poster for sharing; I’ll save and follow it

This post was last edited by luoli519 on 2019-7-1 21:07. Here, a dedicated steam drum for heat removal in a certain synthesis reactor is used as an example for discussion. The process parameters of this drum are as follows: 1. Normal operating temperature: 256℃ ； 2. Maximum operating temperature: 260℃ ； 3. Normal operating pressure: 4.37 MPaA ； 4. Maximum/minimum operating pressure: 4.64/3.72 MPaA ； 5. Normal water supply volume: 88245 kg/h ； 6. Normal water replenishment temperature: 217℃ ； 7. Normal steam generation rate of the reactor: 97,005 kg/h ； 8. Normal steam generation rate: 86,514 kg/h. Technical requirements: 1. Design temperature: 275℃ ； 2. Design pressure: 5 MPaG/F.V.; 3. Two sets of safety valves, with setting pressures of 5 MPaG and 5.15 MPaG respectively; 4. Two sets of safety valves, with load capacities of 50% and 50% respectively; 5. Flow rate handled by the safety valves: 62,770 kg/h ； 6. Safety valve operating temperature: 235 ℃ ； 7. Cp/Cv: 1.36; 8. Material of vapor-liquid separation internals: 316L stainless steel ； 9. Material of the drum shell: carbon steel ； 10. Spraying wash volume: 2% of the total amount.

Since the drum shell can be designed and manufactured in accordance with standards by boiler and pressure vessel factories that possess the relevant design and manufacturing qualifications. We focus on separation technologies that require a high level of technical expertise; such technologies necessitate the use of specialized dynamic separation companies that rely on professional and precise dynamic gas-liquid separation calculation and configuration platforms to meet the process requirements.

But the reason why our peers consulted us about such specialized steam drums for reactors is precisely because their steam drums are not functioning properly. Let’s take a look at the images they have provided and discuss them in detail. First, the heat energy generated by the reactor must be used to create a vapor-liquid mixture of steam and water through saturated water sent from the drum; this mixture enters the jacket surrounding the drum via an opening at the bottom side of the drum, where it undergoes initial vapor-liquid separation and sedimentation before entering the cyclone separator. Due to the limited operational flexibility and low separation efficiency of cyclone separators, simple separation internals such as screens are often required at the tangential inlet of the cyclone.

This post was last edited by luoli519 on 2019-7-2 at 15:34. The wire mesh installed by the internal components supplier at the inlet of the cyclone tower, as shown in the image, is quite amusing. Judging from this screen setup, this supplier of drum internals has never worked on any projects related to steam drums at all, let alone being a company specializing in dynamic gas-liquid separation technology. Let’s take a look at this ridiculous photo of the screen installed at the inlet of the cyclone. A mesh laid out in this format doesn’t serve any separation function at all.