Balancing Hydrogen Demand and Production: Optimising the Lifeblood of a Refinery Luigi Bressan Director of Process and Technology Foster Wheeler

Transcription

1 Balancing Hydrogen Demand and Production: Optimising the Lifeblood of a Refinery Luigi Bressan Director of Process and Technology Foster Wheeler Italiana

2 Agenda Introduction The refinery hydrogen balance Hydrogen production Steam reformer-based technology Partial oxidation (gasification) Partial oxidation (gasification) combined with power production Conclusions 2

3 Introduction H2 NHT CCR Gasoline BPSD CDU & VDU KHT Kerosene PSA 85,000 BPSD DHT Diesel HDCK MODERN REFINERY SIMPLIFIED BLOCK FLOW DIAGRAM DCU 76 t/h Pet Coke 3

4 The refinery hydrogen balance Hydrogen balance 1 Naphtha hydrotreater Kerosene hydrotreater Diesel hydrotreater Hydrocracker 8 t/d 6 t/d 45 t/d 319 t/d 378 t/d PSA s (CCR & HDCk) Difference 156 t/d 222 t/d 104,000 Nm3/h 1 Typical Refinery size 214,000 BPSD 4

5 Hydrogen production The heavier and the sourer the crudes, the larger the hydrogen requirement The larger the HDCk, the larger the hydrogen requirement The heavier the HDCk feedstock, the larger the hydrogen requirement Fresh hydrogen needs can satisfied by: Hydrogen plants based on steam reforming technology Hydrogen plants based on partial oxidation technology Selection depends on feedstock cost and availability, and normally: Steam reforming-based technology processes natural gases and refinery light ends Partial oxidation technology processes heavy oils and petcoke, and even biomass 5

6 Steam reforming-based technology 6

7 Steam reforming-based technology Steam methane reforming (SMR) continues to be the leading technology for hydrogen generation Although SMR is a mature technology, incremental economic improvements are being made by continuous development The plants consist of four basic sections: 1. Treatment to remove sulphur traces and other contaminants 2. Steam methane reformer, which converts feedstock and steam to syngas at high temperature and moderate pressure 3. CO shift reactor/s to increase hydrogen yield 4. Hydrogen purification, in which modern plants use a pressure swing adsorption (PSA) unit to achieve the final product purity In addition to the core process sections, compression is often needed to raise the feedstock and product hydrogen pressures. 7

8 Steam reforming-based technology Hydrogen production plant process flow scheme Steam Steam drum Hydrogen Deaerator PSA Hydrogenator Desulphuriser Pre-reforming Terrace Wall TM steam reformer CW Shift reactor Comb. air Natural gas Air preheating Waste heat boiler Make up water 8

9 Steam reforming-based technology Steam Hydrodesulphurisation section Steam drum Hydrogen Hydrogenator Desulphurizer Pre-reforming Feedstock is hydrotreated Deaerator and resulting H 2 S is captured in a zinc oxide bed. Steam Reformer Terrace Wall TM Shift reactor CW PSA Different schemes are available - the most commonly used is the lead lag arrangement followed by a polishing bed Reaction temperatures are obtained by thermal exchange Natural gas Comb. Air Air preheating Waste heat boiler Make up water 9

10 Steam reforming-based technology Steam Pre-reforming section Steam drum Hydrogen Hydrogenator Desulphurizer Pre-reforming Pre-reforming section Deaerator is generally installed to eliminate the long-chain hydrocarbons PSA in heavier feedstocks before entering the reforming section When natural gas is used as feedstock the prereforming section is beneficial to a reforming CW duty reduction thus lowering the investment cost of the reformer Steam Reformer Terrace Wall TM Shift reactor Natural gas Comb. air Air preheating Waste heat boiler Make up water 10

11 Steam reforming-based technology Reforming section Steam Hydrogenator Desulphurizer Pre-reforming Terrace-Wall TM steam reformer Steam drum Key section of plant Deaerator Uses FW proprietary Terrace-Wall TM technology CW PSA Hydrogen Steam reformer outlet temperatures up to 920 C can be used Shift reactor Natural gas Comb. air Air preheating Waste heat boiler Make up water 11

12 Steam reforming-based technology Steam Steam drum Hydrogen Deaerator PSA Syngas cooling and shift reaction The syngas cooling section is normally optimized Hydrogenator using pinch technology. Desulphurizer Pre-Reforming For the shift reaction section, four options are available: HTS HTS + LTS MTS ITS Natural gas Comb. Air Air preheating Steam Reformer Terrace Wall TM Waste heat boiler Shift reactor CW Make up water 12

13 Steam reforming-based technology PSA section Hydrogen purification is achieved using Pressure Swing Absorption The technology is well-known Process parameters need to be carefully defined to optimise capex Hydrogenator Desulphurizer Pre-Reforming Steam Reformer Terrace Wall TM Steam drum Deaerator CW PSA Steam Hydrogen Shift reactor Comb. air Natural gas Air preheating Waste heat boiler Make up water 13

14 Steam reforming-based technology Refineries can use different feedstock, subject to internal price and availability: Natural gas Refinery gas LPG Light naphtha Heavy naphtha. and even straight-run naphtha Optimising hydrogen plant design and operating parameters depends on the economic values attributed to the feedstock, fuel and steam The characteristics of the feedstock will define the processing capabilities of the plant 14

15 Steam reforming-based technology The optimum is achieved by minimising : (Feedstock(Gcal/h) + Fuel(Gcal/h) Steam(Gcal/h) ) / H 2 flowrate where steam is the net export flow rate of steam from the plant With the proposed scheme a net thermal efficiency of less than 3.0 Gcal per Nm 3 of produced hydrogen can be achieved when starting from natural gas The economical optimum is achieved by minimising: (Feedstock*Cost Feedstock + Fuel*Cost Fuel Steam*Value Steam ) / H 2 flow An accurate pricing of feed, fuel and steam allows a fit-for-purpose design for the hydrogen plant 15

16 Steam reforming-based technology The Foster Wheeler Terrace-Wall TM Reformer Side-fired heater with burners located along lateral walls with flames vertically arranged. Radiant section comprising a firebox with a single row of catalyst tubes with two terraces on both sides of the tubes on which the burners are installed. Catalyst tubes are flanged at the top to allow loading and unloading of the catalyst. Heat is supplied via ultra-low-nox burners (forced- or naturaldraft) Burners are placed at two different levels in the combustion chamber, equipped with a double set of firing tips, one for refinery fuel gas and one for vent gas from PSA unit Process gas boiler is natural circulation type, located at grade level in the middle of the radiant cell, avoiding need for a transfer line. 16

17 Steam reforming-based technology Key advantages of the Terrace-Wall TM design 200,000 Nm 3 /h hydrogen capacity on a single train Modular radiant and convection sections reducing construction time and cost Can operate in natural draft mode keeping the full hydrogen production Very compact design reducing the plot area Leading to: Lower operating cost Lower maintenance cost Lower investment cost 17

18 Steam reforming-based technology Key advantages of the sloping walls in a Terrace-Wall TM design The inclined terrace walls are uniformly heated vertically by the rising flow of hot gases Each terrace capable of being independently heated to provide the particular heat flux desired in its zone Controlled delivery of heat helps control hotspots, maximising tube life The incline of the wall maximises the effectiveness of the terrace to that portion of the heat-absorbing surface Flame impingement on catalyst tubes is practically impossible in the Terrace-Wall TM design 18

19 Steam reforming-based technology The Foster Wheeler Terrace-Wall TM Reformer: continuous improvement Latest developments to deliver further benefits include: Modified geometry of the radiant section to tailor flux profile and improve thermal efficiency without increasing catalyst tube temperature. Outlet pigtails arranged vertically providing better access for easier welding and nipping, removing need for a cold bottom flange for catalyst removal Vacuum-type catalyst removal systems allow removal of catalyst via the tube inlet flange Reduced number of burners by about 30% due to increased capacity, with new burners using staged fuel and air combustion techniques for lower NOx emissions and we continue to develop our design to deliver further performance enhancements 19

20 Partial oxidation (gasification) based technology 20

21 Partial Oxidation technology NHT 214,000 BPSD CCR KHT CDU & VDU PSA DHT HDCK DCU 21

22 22 Balancing Hydrogen Demand and Production: Optimising the Lifeblood of a Refinery Partial Oxidation technology NHT CCR BPSD CDU & VDU KHT PSA DHT HDCK Gasif. DCU Petro-Hy-Power CFB PS. E.P.

23 Partial Oxidation technology ASU PO Syngas Treatment AGR PSA Coke Coke Steam E.P. Acid Gas H2 Offgases Interface with refinery 23

24 Partial Oxidation technology Sufficient coke is sent to partial oxidation reaction The following units are involved: Feedstock storage and preparation Air separation (cryogenic technology) Gasification including black/grey water treatment Syngas treating and conditioning including CO sour shifting and acid gas removal (AGR) Hydrogen production The scheme relies on several interfaces with the refinery It is possible to co-produce electric power with the remaining coke The most convenient and reliable solution is to add a CFB power station PETRO-HY-POWER concept 24

25 Partial Oxidation technology ASU PO Syngas Treatment AGR Steam PSA Offgases CFB Power Station E.P. Coke Coke Acid Gas H2 Interface with Refinery 25

26 Partial Oxidation technology CFB Boiler A clean and efficient use of petcoke for power production By far the most suitable combustion technology for low reactivity, high sulphur fuels like petcoke (biomass and RDF can be added) Limestone can be added to capture the sulphur Fluidizing is achieved by blowing air through the bed material lying on the grid (air distributor); above a certain air velocity, the bed expands and particles become entrained in the flue gas and are carried out of the bed; coarser entrained particles are separated in a hot cyclone and returned The combustion chamber is maintained at a relative low temperature ( C) by suitable heat absorbing surface, thus allowing optimum conditions to remove the sulphur and control the NOx emissions. 26

27 Partial Oxidation technology CFB Boiler The long solids residence time in the furnace results in high combustion efficiency as a consequence of the collection / recirculation of solids via the cyclone, plus the vigorous solids/gas contact in the furnace caused by the fluidization airflow 27

28 Partial Oxidation technology PETROPOWER TM 28

29 Partial Oxidation technology Material Balance Delayed coker Coke production (dry) 76.0 t/d Coke as received 79.2 t/d Coke for PO 63.9 t/d Coke for power station 15.3 t/d CFB power station Gross electrical power ouptut 73.3 MWe Power island consumption 4.2 MWe Gasification island consumption 43.5 MWe Net electric power output 25.6 MWe (available for export to grid or for refinery uses) 29

30 Conclusions Hydrogen is vital for a modern refinery operation Hydrogen generated as by-product in the refinery process units is not enough to cover needs Additional reliable hydrogen must be produced Steam reformer-based technology is the first option to consider Alternatively, gasification (partial oxidation) possibly combined with power production is an interesting opportunity that must be evaluated 30

31 Conclusions Foster Wheeler has: A first-class project execution track record and the technology to help refiners address their increased hydrogen demands at optimum cost Designed, engineered and constructed over 100 hydrogen and synthesis gas plants with a total installed capacity of over 3 billion scfd Extensive experience with its Terraced Wall TM reformer Significant expertise gained through integrating our technology with catalyst suppliers and hydrogen purification systems 31

32 Conclusions Foster Wheeler has: Outstanding experience in gasification plants Deep knowledge of all gasification technologies Unrivalled experience in coke combustion in circulating fluid bed boilers Capability, supported by most sophisticated tools, in integrating process units operation 32

33 Conclusions Foster Wheeler can provide key technologies, FEED services, EPC structure and even BOO However the focus is not only on building new plants, we have significant experience and expertise in: Optimizing and revamping existing hydrogen systems Integrating new and existing systems Foster Wheeler can assist refiners in optimising hydrogen supply 33

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