PTQ Gas 2022 Issue

Figure 1 Refractory surface before sandblasting

Figure 2 Catalytic tubes covered with paper before application

Figure 3 Refractory surface after application

increasing pollution in the econo- miser coils compared to the past. The amount of fuel burned in the furnace and the thermal load of the furnace in these two periods were examined and relatively compared in Table 1 . When the off-gas/fuel gas con - sumptions before and after the application in the SMR furnace are examined, it can be seen that both fuel sources have decreased (the PSA adsorbent change and the increased H 2 recovery rate are also effective in the decrease of the off- gas amount and LHV value). By looking at the closest off-gas and fuel gas analyses to the selected dates, the calorific values were cal - culated and the released energy obtained from the fuel was found. However, the steam production amounts on the selected days for actual comparison are different. When these values and simulation results are examined, it is seen that the amount of heat transferred to the radiant area after the applica- tion increased from 49.8% to 52.7% in the simulation by 2.9%. While an increase of 2.23% is expected in the firm’s forecast, further increase

application. Burner mouths are closed with planks, and it is ensured that no dust or chemicals get into them. The existing refractory surface has been sandblasted to obtain a smooth surface on which the coating will adhere. All of the catalytic tubes are cov- ered with paper and the ceramic coating solution is prevented from contaminating the tubes. The application was made by spraying the prepared water based ceramic coating solution on the refractory surface with pressurised guns. After the application was com- pleted, the sawdust remaining after sandblasting on the floor was vacu - umed and cleaned. Afterwards, the papers wrapped on the tubes were removed and the scaffold in the radiant region was taken out. In the post-application period, with the unit start-up, it has been observed that the adsorbents loaded in the PSA unit were entrained by the off-gas flow and reached the burners of the SMR furnace. While a portion of the adsorbent reaching the burners has burned, the remain- ing part caused some damage to the ceramic coating application surface by spraying from the burners. However, the adsorbent particles reached the convection zone, caus- ing a decrease in the heat transfer and an increase in temperatures in this zone. This made it difficult to separately examine the positive effect of the newly made ceramic coating application. Increasing PSA unit efficiency with adsorbent change during the turnaround and different operat - ing conditions between the selected two days make it difficult to exam - ine the effect of the ceramic coating.

However, two days at the furnace exit temperature at the same H 2 production capacity from the pre- and post-start-up periods were selected for comparison purposes. While these days were selected, a peer based comparison was made with the operation values at the same H 2 production capacity, fur- nace exit temperature, and steam/ carbon ratio. When the temperature points in the upper part of the radiant zone are examined, it can be seen that the temperature in this zone has decreased by an average of 17°C compared to the pre-application. It is also noted that the bridge wall temperature has decreased by an average of 26°C. It is seen that the expected 40°C temperature drop in the company’s forecast is par - tially achieved. These temperature drops indicate that the application gives positive results. Considering the temperature differences in the convection zone, it is seen that the temperatures of the parts close to the radiant zone decrease. However, no decrease in flue gas temperature was observed due to the decrease in the amount of steam production and

SMR furnace fuel consumption relative values

Before application, base situaton

After application

PSA off-gas, kg/h, relatively

1 1 1 1

-1.30%

Fuel gas consumed, kg/h, relatively Off-gas LHV, kcal/kg, relatively Fuel gas LHV, kcal/kg, relatively

0.93 0.93 1.06 0.91 0.99 0.97

Energy given by off-gas, Gcal/h, relatively Energy given by fuel gas, Gcal/h, relatively

1 1

Reaction heat, relatively

Rate of heat transferred to the radiant zone, %, relatively

(+2.9%)

Total energy consumption, Gcal/h, relatively 1 released;

0.93 released (-6,8%); 0.92 absorbed (-8,3%)

1 absorbed

Table 1

Gas 2022 27