Stokers, CHP, Isolated Power Units

Transcription

1 Stokers, CHP, Isolated Power Units

2 Stoker Boilers The term stoker implies a boiler that automatically feeds (or " stokes ) the boiler. Stoker coal size is typically 1.25 inches maximum with less than 30% under 0.25 inche

3 Traveling or Chain Grate Stokers Traveling or chain grate stokers feed coal out onto a rotating metal belt that supports the fire. Coal is fed from a hopper. Grate speed is automatically controlled to maintain desired steam pressure. Burning progresses as the belt moves from front to back of furnace. Combustion is essentially complete at the back end of belt, and ash is dumped off into an ashpit there.

4 Water-Cooled Grate Elements Traveling Grate

5 Vibrating Grate Stoker Vibrating grate stoker is similar to a traveling grate, except that instead of being on a continuous loop, grate sections are sloped downward and periodically vibrate to cause fuel particle movement from front to back. Vibration frequency is controlled to obtain desired steam pressure/ heat output.

6 Vibrating grate Waterwalls Fuel Overfire air nozzles Coal hopper To ashpit Underfire air supply Water-Cooled Vibrating Grate Boiler Vibration generator

7 Underfeed Stokers So named because they use rams to force the coal up underneath the burning fuel bed. Grates are designed to flex up and downs to break up fuel bed and prevent "clinker" formation. Action of feed rams and fuel bed flexing cause fuel to move from front to back of furnace. Underfeed stokers range in size from small home heating boilers to large industrial size. Underfeed stokers are very good at burning high volatile coal with a high turn-down ratio.

8 Fuel Coal hopper Underfeed Stoker Boiler Feeder rams and actuator

9 Spreader Stokers Fed by a rotating bladed wheel that throws the coal out over the grate. Spreaders stokers are more expensive than other stokers in small sizes, and are more expensive than pulverized coal boilers in large sizes (over 500,000 Ibm/hr of steam) but are very common in the intermediate (large industrial) size range. Compared to previous stokers, more fuel burning occurs in suspension- that is, in the air as the fine particles are slung out over the fuel bed.

10 Spreader Stokers (Cont d) Because of feeding method, more small particles and fly ash are carried up with the exhaust. Particles trapped up in boiler, economizer, air preheater and dust collectors are recycled for better combustion efficiency and reduced particulate emissions. Grates are of several types. Some are traveling or vibrating to move fire from back to front of furnace and dump ash over the front into an ashpit. Others grates periodically are turned over to collect ash.

11 516 Fuel hopper Fuel feeder Airborne fuel Spreader Stoker Boiler

12 Coal Feeders

13 PC vs. Stoker Boilers: Advantages/Disadvantages Advantages of PC vs. stoker boilers: much quicker response to changing loads lower excess air/higher efficiency easily adaptable to automatic control can burn wide variety of coals Disadvantages of PC vs. stoker boilers: more expensive (at least for smaller capacities) require more skilled personnel require better emission control (particulates) require more energy to pulverize fuel

14 CHP 101 and Opportunities Bruce Hepke Sustainability Engineer KPPC (502) Isaac Panzarella Director Southeast CHP TAP (919) Jason Volz Energy Engineer Harshaw Trane (502)

15 Outline CHP 101 What is CHP and Benefits? Technical Potential for CHP in Kentucky Case Studies Barriers to CHP Win-Win Strategies for CHP Technical Assistance Opportunities Next Steps

16 What Is Combined Heat and Power? CHP is an integrated energy system that: Is located at or near a factory or building Generates electrical and/or mechanical power Recovers waste heat for heating, cooling or dehumidification Can utilize a variety of technologies and fuels

17 Fuel Utilization by U.S. Utility Sector Source:

18 Defining Combined Heat & Power (CHP) The on-site simultaneous generation of two forms of energy (heat and electricity) from a single fuel/energy source Conventional CHP (also referred to as Topping Cycle CHP or Direct Fired CHP) Separate Energy Delivery: Electric generation 33% Thermal generation - 80% Combined efficiency 45% to 55% CHP Energy Efficiency (combined heat and power) 70% to 85%

19 Defining Combined Heat & Power (CHP) The on-site simultaneous generation of two forms of energy (heat and electricity) from a single fuel/energy source Waste Heat to Power CHP (also referred to as Bottoming Cycle CHP or Indirect Fired HRSG/Steam Turbine Organic Rankine Cycle Backpressure Turbine Steam Turbine Electricity Heat CHP) Fuel first applied to produce useful thermal energy for the process Waste heat is utilized to produce electricity and possibly additional thermal energy for the process Fuel Heat recovery steam boiler Energy Intensive Industria l Process Waste heat from the industrial process Heat produced for the industrial process Simultaneous generation of heat and electricity No additional fossil fuel combustion (no incremental emissions) Normally produces larger amounts electric generation (often exports electricity to the grid; base load electric power)

20 What Are the Benefits of CHP? CHP is more efficient than separate generation of electricity and heat Higher efficiency translates to lower operating cost, (but requires capital investment) Higher efficiency reduces emissions of all pollutants CHP can also increase energy reliability and enhance power quality On-site electric generation reduces grid congestion and avoids distribution costs

21 Attractive CHP Markets Industri o al Chemical manufacturing o Ethanol o Food processing o Natural gas pipelines opetrochemicals o o o Pharmaceuticals Pulp and paper o Refining Rubber and plastics Commerci odata centers al ohotels and casinos o Multi-family housing o Laundries o Apartments o Office buildings o Refrigerated warehouses o Restaurants o Supermarkets o Green buildings Institution o Hospitals al o Schools (K 12) o Universities & colleges o Wastewater treatment o Residential confinement Agricultur o al o o Concentrated animal feeding operations Dairies Wood waste (biomass)

22 CHP Today 82.4 GW of installed CHP over 4,200 industrial and commercial facilities (2012) 87% of capacity in industrial applications 71% of capacity is natural gas fired Avoids more than 1.8 quadrillion Btus of fuel consumption annually Source: ICF CHP Installation Database, 2012 Data Avoids 241 million metric tons of CO 2 compared to separate production

23 CHP Is Used at the Point of Demand 4,200 CHP Sites (2012) 82,400 MW installed capacity Saves 1.8 quads of fuel each year Avoids 241 M metric tons of CO 2 each year 87% of capacity industrial 71% of capacity natural gas fired Source: ICF International

24 Existing CHP Systems in Kentucky SIC Code Company/Site City Year Open Source: 2013 ICF International Database for ORNL Capacity (MW) Technology 24 Cox Interior Inc Boiler/Steam Campbellsvill Turbine e 24 Domtar Hawesville Boiler/Steam Turbine 24 Cox Lumber Waste Heat Campbellsvill Recovery e 24 Young Waste Heat Manufacturin Recovery g Company Beaver Dam 28 Air Products & Combustion Chemicals, Inc. Calvert City Cycle 31 Owensboro Reciprocating Grain Owensboro Engine 32 Continent al Building Products Combustion Cycle Fuel Biomass Biomass Waste Heat Waste Heat Natural Gas Natural Gas Natural Gas Silver Grove 65 Western Reciprocating Natural Gas

25 CHP Technical Potential is Nationwide 2 Sou1 rce: 2013 ICF International Estimates

26 1, Existing and Technical Potential for CHP in Kentucky Source: 2013 ICF International Estimates Tech Potential - Export Tech Potential - No Export Existing

27 CHP Case Studies CHP is not always sold on economics alone Multiple fuel sources can be used Heat can be used for multiple purposes Case Studies (Project Profiles) located at gy/projects_sector.html#healthcare

28 Young Manufacturing 320 kw o Steam was initial present for mill processes o 2 steam turbines were installed to be powered by excess heat from steam boilers 120 kw 200 kw o Boilers are fueled by mill waste Biomass Boiler Generator (200 kw) and turbine

29 US Army Retail Center 2 MW o 2.0 MW Lean Burn Reciprocating Natural Gas Generator o Exhaust recovery produces chilled water o 495 tons of absorption cooling o Hot water recovery from engine produces 6.5 MMBtu/hr o BACT significantly reduces versus emissions traditional system NG Generator (2 MW) with BACT

30 US Army Data Center 2 MW o 2.0 MW Lean Burn Reciprocating Natural Gas Generator o Exhaust and Hot water recovery produces chilled water o 705 tons of absorption cooling serves data center CRAC units o CHP system serves both day-to-day and emergency power 705 ton Absorption Chiller Exhaust and Hot water driven

31 Domtar-Hawesville 65 MW o Steam produced by burning waste pulp liquor and wood biomass o High pressure steam GENERATOR used to power turbine o Turbine generates electricity at kv o Remaining steam used in industrial process o 70% of plant power produced onsite TURBINE

32 Russell, KS Municipal Partnership 15 MW o (2) 7.5 MW combustion turbines o Fuel by natural gas o Heat recovery steam generators (HRSG) provides 65,000 lb/hr steam o Exhaust from HRSG used in drying process Source:

33 US Army Hospital 4 MW o 4.0 MW Lean Burn Reciprocating Natural Gas Generator o Exhaust recovery produces 7,600 lb/hr of medium pressure steam o 640 tons of absorption cooling produced from hot water recovery o Installed to create fully redundant heat, chilled water, and power production for hospital Waste eat boiler Exhaust driven

34 University of Cincinnati 47 MW o District Heating and Cooling serving 6 hospitals and entire university o Natural Gas Turbines and steam turbine o 610,000 lb/hr peak steam production capacity o 3,400 tons of absorption cooling available o Matches grid electric reliability rating of 99.98%

35 A Number of Prominent Barriers to CHP o Large Capital Investment which many companies are not ready to make Long payback periods by their standards Not directly related to their main area of business o Discouraged by many electric utilities Utility regulatory framework often does not encourage CHP and there is poor understanding of risks/rewards Utilities encouraged to invest in central station power and upgrading the present grid structure (larger rates of return on their investments) o Increases site emissions while reducing overall No credit given for emissions reduction from power plants

36 Interconnection Policies usa.org / Fe bruary State s, + Washing ton DC and Puerto Rico, have adopted an interconnection policy. Notes: Numbers indicate system capacity limit in kw. Some state limits vary by customer type (e.g., residential versus non-residential). No limit means that there is no stated maximum size for individual systems. Other limits may apply. Generally, state interconnection standards apply only to investor-owned utilities.

37 Real time pricing offers a win-win CHP strategy o Princeton University has a 15 MW gas turbine CHP system, operated to maximize savings by reducing demand on grid during peak pricing times. Peak utility power pricing CHP operated at baseload to meet thermal demands CHP operated at peak to reduce grid demand Borer, Ted Talk on CHP & Campus Sustainability for International District Energy Association. February 2013;

38 CHP with District Energy & Microgrids o o Local distributed generation integrating CHP; thermal energy; electricity generation; thermal storage and renewables Able to island in the event of a grid failure Illustration, copyright AEI / Affiliated Engineers, Inc.

39 Capacity (MW) CHP in Colleges & Universities 285 colleges and universities have CHP, totaling 2,714 MW of capacity. 3,500 3,000 2,500 CHP Growth at College/Universities Represents 3.3% of total installed CHP capacity in the U.S. (82 GW) Further technical potential totaling 8,403.9 MW of capacity 2,000 1,500 1, Source: ICF CHP Technical Potential Database

40 CHP and Critical Infrastructure Critical infrastructure refers to those assets, systems, and networks that, if incapacitated, would have a substantial negative impact on national security, national economic security, or national public health and safety. Patriot Act of 2001 Section 1016 (e) Applications: o Hospitals and healthcare centers o Water / wastewater treatment plants o Police, fire, and public safety o Centers of refuge (often schools or universities) omilitary/national Security o Food distribution facilities otelecom and data centers

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