Lessons learned from Shell’s gasification process

1. If coal is too dry, with its moisture content dropping below 1%, the flowability of the coal powder becomes extremely poor, transportation becomes difficult, and bridge formations occur. 5 J; \; _$ D- f; a8 g+ z: C- Z Reason: Excessive time was spent using nitrogen to purge the coal in the hopper or coal bin during maintenance. The standard drying temperature for Shell’s process design is 100–105 degrees, whereas in one project 70 degrees was sufficient. 6 a2 O8 Y1 O1 Z7 ^+ W Measures: (1) Determine an appropriate drying temperature to keep the moisture content of the coal powder at 1-2%. $ h6 B* S; j( P3 c; 9 k3 @ (2) When driving, the coal powder circulation should follow a burner-by-burner sequence. + J7 ?: N& Z- O( s6 m# R3 ] 5. There are issues with the accuracy of weighing (mainly V1201); the weight sensors are not accurate. Reason: Rigid connection installation; poor installation quality leads to stress. % Z1 F/ l) }+ N" }2 x% \( N Measures: (1) Improve the accuracy of weighing instruments. 9 Z1 G3 |# l! T( v( n （2）Check the alignment during weighing, and adjust the bellows as appropriate. 6. The V1204 ventilation unit is damaged. Measure: Temporarily: Change the control logic 12KS0001 to ensure even distribution of nitrogen through the ventilation cones and grooves. Maintain continuous purging during both stationary and operating conditions. The boost speed also needs to be limited, and the downside is that it takes time. , f9 ; e! p* . `4 G6 e 13 – Impurities in the coal powder caused blockage of 13FV0101, leading to unstable flow rates and making it difficult to control the oxygen/carbon ratio. . x" h$ \8 A* q' I) m( v Reason: Debris in the valve. Action: (1) Install a filter below S1103. (2) During debugging, U1200 must be cleaned thoroughly; all bolted connections should be spot-welded or secured with double nuts. - u& W% f4 Q5 T! W! O6 `3 s 14. Rapid corrosion of the pressure reduction devices in the middle and lower sections of the coal circulation pipeline: Severe corrosion occurs due to coal powder accumulating on the pipe walls too quickly. Measures: (1) ； Increase the distance between the pressure reduction device and the lead. (2) Use wear-resistant materials (mainly ceramics). $ K3 K. n2 N5 s; f& ?. Y% w1 N 15. The ability of the pilot burner is insufficient. 0 h: j h1 e5 m! ?! Q5 k4 f/ x. Reason: The pilot burners vary depending on the project, and their design capacity is too low to ignite the main burner for operation. : s `8 D4 5 h- ^* S9 p( m# a& X （2）Optimize welding quality and install gaskets correctly. ' I3 g2 l$ J1 O# d- R 26: The protection and control functions of 02/C are based on the same instruments. Measure: 02/C should be based on protection instruments rather than control instruments for triggering shutdowns. 27. The calculated vaporization temperature is unreliable. Measures: (1) Determine the correct calculation formulas in the DCS to calculate the temperature of the quench gas in the vaporization furnace as well as the inlet temperature of GRC. (2) The detection signal taken into account in the calibration formula. " c1 |7 U0 N3 B8 R7 d 28: The bottom of the vaporization furnace may be damaged due to a power failure of the circulation pump (P1301). Reason: After the vaporization furnace stops operating, the heat remaining in the slag layer (low cone) and the refractory materials must be removed; a failure of the circulation pump or insufficient water supply can lead to damage to the slag layer (low cone) and the refractory materials. Measures: (1) An emergency power supply must be installed. 5 S! @5 z/ K F3 j9 P! L# M f (2) The circulation pump must ensure the required flow rate.) k. }2 t$ G& C5 W3 H% M1 S 29. The structure of the P1301 filter does not meet the requirements. 9 @+ P3 m/ | D: n8 C7 M0 s Measures: (1) Order the filter in accordance with SEG’s technical specifications. 30. Faulty three-way valve (incorrect position). 13XV0108& o: h" l% _4 V, J$ c. Reasons: (1) Mechanical failure; (2) Incorrect positioning. 6 Q, q+ a5 \# l/ |+ b5 |( v (3) Improper maintenance. ) z/ `3 r$ v8 V3 v2 T (4) Poor thermal insulation and heating. / e. s' G9 }& M Measures: (1) Proper tracking. 4 M; @+ U8 Q8 c# {2 m (2) Proceed according to the maintenance plan. (3) Turn it on and off several times before driving. $ S5 d& G5 y! D" b7 W2 h 31: The coal flow control valve (13FV0001) is clogged or operates unstably. Cause: Impurities in the coal (mainly nuts, bolts, etc. from the raw coal and Unit 12). {1 m( A- p$ c) b. Measures: (1) Install a filter at the coal outlet of S1103 3 i( Q* {0 q# }- V) c; (2) Tighten the upstream internal components + y) ?2 {) Z7 @$ {. h4 o, x. 32: Slow heating up of the vaporizer and SGC. Cause: The temperature sensing point of 13TI0054 is located at the lowest position. Measurements: It is recommended to use 13TI0057 for temperature measurement, with the maximum temperature difference between the housing and the internal components of the vaporizer not exceeding 75 degrees. 33. An LHHH alarm occurred at V1304 level 13LI0040, causing the vaporization furnace to shut down. Reason: (1) No alarm was issued due to an incomplete DCS configuration, or the alarm location was inaccurate. (2) High liquid level reports are too late. Measurements: Contact the instrumentation team for handling; f; W’ b+ Z* z+ b, x7 P 34. The safety valve on the main superheated steam pipeline may activate accidentally. Cause: The original setting pressure of the safety valve is incorrect. 6 h2 ^; j9 k" U3 36. It is not possible to monitor the performance of the coal burners: Z# ~! o2 \+ v' x* ? Reason: The temperature control systems for each coal burner do not have temperature sensors installed at their inlets and outlets. Solution: Install temperature sensors at the inlets and outlets of the temperature control systems for each burner, as close as possible to the cooling water outlets of those burners. 1 Y9 W$ _6 Z( b' \ J8 \ 37. P1301 is damaged. Reason ； (1) Due to poor quality of boiler water, scaling occurs during operation. (2) Measures to address the contamination of boiler water, which led to damage to the pump’s seal box ； (1) Maintain the water quality of the boiler water to prevent scaling. (2) Remove the dirt from the system. 4 \4 S- y# N* X# U( V9 ( M 41. Damage to the bottom of the quench tube: Insufficient cooling due to a manufacturing error. Measure: Temporary: Install fire-resistant material at the damaged area again. ' @, {. S4 D+ | h h" Q w Permanent: Install a U-shaped elbow at the correction point. 42. Unstable measurement of coal flow rate. Reasons: (1) Incorrect installation location; (2) Impurities in the coal! ?3 z, @2 F2 }: t8 ~ Measures: (1) 13SI0001 should be as close as possible to control valve 13FV0101, with at least 50 times the pipe diameter behind it in a straight section. * J: K; G- d8 z- b (2) Refer to 33 & h+ D/ l- a z8 w* O# Q, W 43. The temperature control of the vaporization furnace is incorrect. Measures: (1) The operation control of the vaporization furnace is based on the amount of steam generated by it, 13FY0047; carbon dioxide control serves as a supplementary mechanism, while methane control can be omitted. This is all part of the overall design. (2) The shape of the slag is the final operational inspection. 44. 13FT0047 cannot effectively measure the percentage of steam generated by the vaporization furnace. Reason: Liquid level control failures in the vaporization furnace and the SGC gas holder prevent 13XV0049 from closing. Measures: (1) Arrange the pipes according to SGC’s piping plan and install the relevant venturi tubes. # W, @3 d+ u! Q6 y* s. The Dongting lake system has achieved level control in accordance with the SGC specifications, and no issues have arisen. 8 a. a3 K0 b: X% O$ ` 45. Corrosion of the water-cooling wall tubes in the syngas cooler (V1302). Cause: After the pressure test for heat transfer is completed, water remains in the water circuit, which may lead to corrosion. 5 `! m& W, D8 l: & t$ |5 @, V% t; c. Measures: Use a diaphragm gauge for pressure readings, and check the size of the balance holes inside the skirt. ; & y: ^ Reason: Insufficient electric heating power. Measure: Ensure that the pipe ends and pressure gauges also have appropriate heat tracing. 62. Damage to S1501 filter rod: The reason is that the venturi tube on the tube side was not secured properly, causing the support for the reverse-blow venturi tube to fall off. Measures: (1) The connection between the venturi tube and the tube side needs to be strengthened. (2) An internal connection is required between the venturi tube and the backflow nozzle. (3) The backflow should occur in the middle, not on the sides. " S) i% g# I, m- A& A3 Q, u 63. Cause of contamination in the low-pressure N system: Damage to the bracket in V1508. Action taken: Improve design and manufacturing quality. 8 V1 i% S; I3 c3 a4 O( z 64. Issue with acid addition in C1701: Cause: Misunderstanding of the valve’s function. 9 d' E9 V% [4 ~- \& d$ P- T5 i Measure: Change the acid injection point

Well written; it has real substance.