How many days does it take to successfully commission a sulfur recovery unit?

Under normal operating conditions, it takes about a month.

Is about a month the time for the first start of work? How long will it take to drive normally again?

This post was last edited by Kaikai24 on 2017-9-6 at 15:50. It runs from 12:00 on the first day to 12:00 on the seventh day, for a total of 154 hours. 1. Preparation work before starting up: (1) Draw the furnace heating curve. (2) Prepare the amine solution required to start up the concentrated solvent system and the exhaust solvent system. 2. Startup steps (I) Startup of the sulfur recovery unit: (1) Start the fans to establish circulation in the process gas system, perform purging, and ensure airtightness. (2) Seal the fuel gas system, hydrogen system, and acidic gas system with nitrogen. (3) Introduce the fuel gas into the device and verify that it meets the requirements. (4) The medium-pressure steam superheating coil is protected by supplying steam at 1.0 MPa. (5) Light the incinerator and raise the temperature according to the furnace drying curve. (6) Fill the drum and sulfur cooler with water; allow venting at the top and maintain a small amount of drainage at the bottom. (7) Ignite the furnace and raise the temperature according to the furnace drying curve. (8) Commissioning of the exhaust gas treatment unit a) Establish water circulation in the quench tower. b) Establish an exhaust gas circulation to raise the temperature of the hydrogenation reactor to the temperature required for presulfurization. Nitrogen is used for displacement to keep the oxygen content in the exhaust gas circulation at less than 0.5%; a small amount of hydrogen and acidic gases are introduced into the hydrogenation reactor to initiate catalyst presulfurization. By increasing the inlet temperature of the hydrogenation reactor, and adjusting the amount of acidic gas and hydrogen added based on the analysis results and the on-line hydrogen analyzer, the temperature rise in the reactor bed was observed. Catalyst presulfidation is completed when the H2S concentrations at the reactor inlet and outlet become essentially the same, and the bed temperature stops rising or shows a slight decrease. (9) Tail gas solvent system: water flushing, airtight. The amine introduction liquid and the exhaust solvent system are used to establish a cold cycle; thereafter, heating steam is introduced, causing the exhaust regeneration tower to increase in temperature and pressure and thus establishing a hot cycle. (10) Check and confirm that the liquid sulfur pipeline and its heating system are unobstructed, and that the liquid sulfur valves are functioning properly. (11) After the heating of each furnace and reactor is completed, the equipment and pipelines in the acidic gas system are airtight with no leaks. Control various process parameters to meet the conditions for introducing acidic gas, and introduce the acidic gas into the conversion furnace. (12) Adjust the operations of the sulfur recovery unit to stability, and introduce exhaust gas into the exhaust gas treatment unit. (13) Adjust the operation of the sulfur recovery and exhaust gas treatment units to keep all parameters within the specified process limits. (14) Check the color and flow of liquid sulfur. When the liquid sulfur does not meet the standards, it is discharged into the waste sulfur tank; once it meets the standards, it is poured into the sulfur pit, allowing normal production to resume. (II) Commissioning of the centralized solvent regeneration unit (1) Flushing of the unit’s circulating water. (2) Seal the regeneration tower, acidic gas system, and flash tank with nitrogen until they meet the requirements. (3) Introduce the amine solution; a cold cycle is established in the amine solution system. (4) Introduce heating steam; the regeneration tower’s temperature and pressure rise, thereby establishing a hot cycle. (5) A rich liquid feed device is introduced into the plant; the operating parameters are adjusted to stay within the specified technical limits. Sampling analyses show that the quality of the lean liquid is satisfactory, and the device then enters normal operation.

Seven starts and eight stops represent the normal operating time; if the requirements regarding the furnace heating curve are relaxed, the time can be significantly reduced, but this comes with safety risks.

How is the time allocated for seven hours of operation and eight hours of downtime? Is the time period quite long?

The startup process mainly involves furnace drying and system heating-up time. The startup of the acid water stripper and solvent regeneration sections can be carried out concurrently with the system heating-up, without adding to the overall duration. During shutdown, sulfate reduction and catalyst thermal immersion occur over fixed periods of time; sulfur purging in the system depends on the level of control and operation, while the cooling time for the system is also generally fixed. The passivation of the hydrogenation reactor can be carried out simultaneously.

State-owned enterprises and large, established refineries generally follow the planned schedules for starting up and shutting down operations. However, it’s harder to say the same for smaller refineries in some areas; I’ve seen cases where a plant could start operating again within three or four days, and stop operating in less than four days – that’s really impressive. I don’t care about anything like the furnace heating curve, the cooling curve, or the bed temperature.

The most time-consuming parts are heating up and cooling down. Does it go into interlock mode right after sulfur injection is completed?

That’s not the case; it’s just that the temperature doesn’t rise or fall in a gradual manner.