PTQ Gas 2022 Issue

despite the PSA drift experienced shows that the implementation was successful. Calculation of the increase as 2.9% as a result of the simulation indicates that the appli- cation would yield better results if PSA drift had not occurred. As a result of the simulation, if no nor- malisation is made for the operating conditions for different days, the heat released by the fuel decreases by 6.8%; the heat absorbed in the tubes decreases by 8.3%. The selected two days were nor- malised according to all conditions (PSA efficiency, S/C ratio, boiler feed water temperature, coil cleaning) and the results were tabulated (see Table 1 ). • A 9% reduction in extra fuel load (in Mkcal/h) is expected for the same H 2 production • A 3.5% reduction in the released load of the furnace is expected for the same H 2 production • For the same H 2 production, a 4.5% reduction in the absorption load of the furnace is expected • An 8% decrease is expected in the amount of HP steam sent to the refinery for the same H 2 production The economic return of the appli- cation was calculated over the nat- ural gas equivalent of the amount of energy saved in the furnace. The decrease in total energy consump- tion corresponds to the natural gas amount of 588 t/y, which corre - sponds to 240 k$/y. Despite the negativities expe- rienced and the large number of variables, these returns are the min- imum returns calculated, and it is estimated that higher returns can be obtained from the application under normal conditions. The economic return of the application cannot be calculated using the simulation results. In this case, it is seen that the application made with a cost of 286 k$ covers the investment cost within one to two years. Conclusion and evaluation High emissivity refractory coating application was applied by a well- known company in the hydrogen unit’s planned turnaround. The ceramic coating applied to the radi- ant zone refractory surface aimed to absorb the heat more at the same

The model calculates the product H 2 and tail gas produced based on the natural gas, CCR gas or recycle gas entered. In the model, the radi- ant load rate was entered manually and the extra fuel and HP steam production needed in the unit were calculated. According to the field data (especially based on the extra fuel consumed in the field and the HPS produced), the radiant load rate for those days was found. After the application, it was observed that the radiant load ratio increased by approximately 2.9% compared to the past. Comparing the field data alone is not enough, and the company’s ceramic coating result can be seen by bringing the different operational parameters of the two days to the same base in the simulation model: • PSA efficiency was around 87% before the application, while it was 89.7% after the application. This efficiency difference affects H 2 pro- duction, the residual gas quantity, and the residual gas LHV. As PSA yield increases, the amount of TG and LHV decrease. This creates an increase in extra fuel. • While the gear input tempera- ture is 359°C before the application, it is 320°C after the application. This affects both H 2 production and residual gas LHV. The residual gas LHV increases at high temperature. This reduces extra fuel consump- tion. Low temperature increases H 2 production and lowers residual gas LHV. • Before the application, an increase in pollution was found in the con- vection coils compared to after the application date. This increases the extra fuel load and reduces steam production. • Before the application, the SR working pressure was around 26 kg/ cm²g, while after the application it was around 24 kg/cm²g. Low pres - sure increases both H 2 production and furnace load. • Furnace excess O 2 is around 2% before the application and around 3% after the application. High excess O 2 increases fuel gas consumption and steam production. • Before the application the unit BFW inlet temperature is higher. There is no natural gas and CCR

combustion load in this zone The application of the coating was car- ried out successfully, but the pos- itive effect of the application was limited due to PSA adsorbent entrainment after the unit start-up. Thanks to the application in the evaluation: • It has been observed that the tem- peratures in the upper part of the radiant zone and the bridge zone of the SMR furnace are lower for the same production capacity and oper- ating conditions. While 40°C was predicted according to the compa- ny’s prediction, it was observed that this value was realised as 26°C after the application. • Evaluating the thermal load of the furnace, it was observed that the heat used for H 2 production in the radiant zone increased by 2.9% compared to the pre-application simulation results (this value was predicted as 2.23% by the company before the application). • It has been determined that when the operational conditions are equal- ised (such as PSA rec., shift T) as a result of the simulation for the same capacity as the application, it will consume 2.75 Gcal/h less additional fuel energy. There is an 8% decrease in HPS production. • The economic return of this sav- ing (additional fuel - HPS) was cal- culated as the reduction in natural gas consumption over actual values and was found to be 240 k$/y with actual values. • As a result, it has been observed that the application has a positive effect on the temperature profile in the furnace and reduces fuel con- sumption by saving heat. Even though the effect of the PSA adsor - bent entrainment on the possible earnings was negative, the appli- cation was realised in a situation where it pays itself back within one year, thanks to the total gain. APP-1 H 2 simulation model outputs The hydrogen unit simulation model was created to incorpo- rate the hydrogen unit furnaces convection section, SMR reactor, shift reactor, and TEMA type heat exchangers into the unit. The model was checked against both the design condition and various field data. 3

28 Gas 2022