SCOoPE 07 – Energy efficiency in food industry and combined heat and power

November 19, 2019 0 By William Morgan


Welcome to Chapter 7 of the WEBINARS series developed by the SCOoPE Project. The title of this webinar is “Energy efficiency in food industry and combined heat and power (CHP)”. I am Alberto Mastrilli and this video has been produced thanks to a joint work… …of some colleagues of ENEA,
namely: Arianna Latini,.. …Germina Giagnacovo
and Carlo Alberto Campiotti. ENEA is an Italian partner of EU SCOoPE Project,
it is a Governmental Research Center,… …and its acronym stands for the “Italian National Agency for New Technologies,… …Energy and Sustainable Economic Development”. Firstly, we will shortly show some data
of the european food sector,… …and the most important characteristics of food industry in terms of energy flows… …and amounts, and types of energy
required from plants… …in the industrial food processing chain. Afterward, we will describe the complexity of the processes that characterize food industry… …and their major features.
We will explain why the CHP technology… …represents a good answer to implement energy efficiency in the food industrial processes,… …i will show you used technology,
cost and benefits,… …and we will see an example
of CHP in a video. Let’s start! The whole food chain, at the European level,
including agriculture,… …food and beverage industry, and distribution (wholesale and retail),… …is of great importance in terms of turnover,
value added and employment. In Europe, the agricultural area used is
about 170 million hectares,… …with 12 million farms, and a turnover
of 1016 million euros… …and about 4.2 million people
(Eurostat 2010). According to FoodDrinkEurope data for 2011,
the aggregate of these components,… …which represents the so-called “bio-economy”
sector at European level,… …is estimated just under 400 billion Euros
in agriculture (including fishery and forestry);… …beyond 1,000 billion for the food industry, while the overall distribution exceeds 2,200 billion. A 2015 JRC Science and Policy Report on
“Energy use in the EU food sector: State of play and opportunities for improvement”
states that agriculture,… …including crop cultivation and animal rearing,
is the most energy intense phase… …of the food system,
accounting for nearly one third… …of the total energy consumed
in the food production chain. The second most important phase of the food life
cycle is the industrial processing,… …which accounts for 28% of total energy use. Together with the logistics and packaging,
these three phases of the food life cycle… …are responsible for over half of the total energy
use in the food system. The “end of life” phase, including final
disposal of food waste,… …represents only slightly more than 5% of total energy use in the entire EU food system. Food waste actually occurs at every step
of the food chain. Which are food industry features? Let’s see more in detail the food industry features
that caracterized the industrial food sector;… …it differs from others for the multiplicity
of processing processes,… …product diversification, and the relative energy
mix used to produce them. The amount of energy needed to produce 1 kg
of food may vary from a minimum… …of 0.5 KWh to a maximum of 61 KWh,
depending on the type of food considered. If we focus our attention on the industrial sector,
this results in a great variety of product processing,… ..requiring energy in the forms of electricity,
heat, refrigeration. Industrial processes often produce
waste that can be used… …for energy production,
in a direct combustion… …or after anaerobic digestion
with gas production. The following diagram summarizes
the processing phases that place… …the products in the so-called:
“from farm to fork” path. This other slide, more in detail,
refers to the processing… …processes of the food
and beverage industry. Here the processes are grouped in order to show
a general pattern of processes: Reception and preparation of feedstock,
Processes for reducing dimensions, mixing, shaping,… …Separation processes, Treatment processes,
Baking processes, Heat-concentration processes,… …Heat removal processes, Post-Process Operations, other Service processes. Thanks to this reason, food industry is an excellent candidate for the use… …of Combined Heat and Power (CHP)
technology due to: – The type of energy mix required
(contemporary uses of electricity, heat); – The availability of waste to produce biogas
and thus energy,… …but also utilized for generate
fertilisers/soil improvers; – The current EU policies on energy saving,
use of renewable sources,… …and GHG emissions reduction, as addressed by the Renewable Energy Directive (RED-2009/28/EU)… …and the Energy Efficiency Directive
(EED-2012/27/EU). Before making any investments in the direction
of energy efficiency, is very important that every… …company carry out the so-called “energy audit”
which is a detailed analysis of production processes,… …a reconstruction of energy flows and raw materials, and the technologies involved. Once awareness has been gained, the sectors
with high potential savings are identified,… …and possible new technologies
that can provide… …an innovative response to the company’s
real needs. This accurate procedure is needed
so that can be made… …the right choices in terms of investments
to improve energy efficiency,… …money saving in order to make
further investments. But what is CHP? Much of the electricity generated
in the world comes from fossil fuels,… …or from nuclear plants, where high temperature
heat is first converted… …into mechanical energy and therefore into electricity
by means of electric generators. The conversion of heat into mechanical energy, takes place thanks to a fluid into a thermodynamic cycle,… …whose maximum performance is given by the
carnot cycle, and it is impossible according… …to the principles of thermodynamics, to convert
oll the heat in mechanical energy. In traditional power generation systems,
untransformed heat is lost;… …this results in low energy conversion… …efficiency between the energy contained… …in the fuel and electricity produced… …(typically 35-40% in modern power plants). Contrary to this, CHP technology consist
in the simultaneous utilization of heat… …and electric power from a single fuel source source,
at or close to the point of use. An optimal CHP system will be designed to meet
the heat demand of the energy user,… …and since it costs less to transport surplus
electricity than surplus heat,… …CHP can be viewed primarily as a source of heat,
with electricity as a by-product,… …often used directly in the same industry or,
if in excess, provided to the electrical grid. By using the heat output from the electricity production for heating or industrial applications including… …refrigeration through the use of absorbing chillers
(in this case we are tolking about trigeneration),… …CHP plants generally convert 75-80%
of the energy fuel source into useful energy,… …while the most modern CHP plants reach
efficiencies of 90% or more (IPCC, 2007). A traditional plant Separated Heat
and Power (SHP) can reach typically… …35-40% of conversion in modern
power plants for electricity,… …and 75-80% for heat production,
while the remaining energy is lost. Cogeneration allows for using the waste heat… …and thus enhancing the overall system efficiency; For a cogeneration plant it is possible
to define a set of performance indexes… …that provide objective information about
the quality of the plant and its ability… …to exploit the primary energy introduced with the fuel. Let’s see the most importants: 1) CHP electric efficiency that
indicates how much… …of the fuel energy is converted
into useful electric energy. 2) CHP heat efficiency that indicates how much of the fuel energy is converted into useful thermal energy. 3) The energy utilization factor indicates how
much of the fuel energy is effectively used… …into electric or thermal form, and it can reach value
of 0,8 or more in modern CHP plants. The most important parameter in cogeneration
is ‘heat to power ratio’ which determines… …the proportion of generated heat to electrical
power in a single cogeneration system. Each facility has different demand
of heat and electricity and those… …demands should be matched with
the heat to power ratio of different… …cogeneration systems to select
the most appropriate one. So the heat power ratio vary from site to site,
and it can range from 0.6:1 for an internal… …combustion engine with only exhaust-gas heat recovery, to 10:1 for a steam turbine. As a result, the CHP system must be selected… …to match these demands as closely as possible. CHP plants consist of four basic elements:
a prime mover (engine),… …an electricity generator, a heat recovery system,
and a control system. The prime mover,
while driving the electricity generator,… …creates usable heat that can be recovered. CHP units are generally classified
by the type of prime mover. Theoretically, almost any fuel
is suitable for CHP,… …although for new systems, natural gas
currently predominates. Other common fuel sources include fossil-fuel
based commercial fuels (i.e. coal, diesel),… …municipal solid waste, and biomass.
As biomass and industry-derived gases… …become more available and cheaper, they will be of increasing importance, due to growing environmental… …and energy security concerns.
Some CHP plant can use multiple fuel types,… …providing valuable flexibility at a time of growing
fuel insecurity and price volatility. Obviously liquid or gas fuels are utilized for internal combustion engines,… …while solid fuels too can be utilised
for steam production. In electrical output terms, CHP plant sizes range
from 1 kWe (kilowatt electric)… …to over 500 MWe (megawatt electric).
For larger plants (greater than 1 MWe),… …equipment is generally site-specific, while smaller-scale applications can use pre-packaged units. Energy-intensive industrial sites in the food processing, have been traditional hosts for CHP facilities;… …in fact, the energy intensive industries,
as the food industries represent… …more than 80% of the total global electric
CHP capacities (IEA, 2007). These plants generally have high process related thermal requirements not subject to daily… …and seasonal weather-related fluctuations,
so energy is an important part of their business,… …and operation and maintenance personnel are available and competent to manage CHP systems. Three main technologies are used in typical
industrial CHP systems. These technologies, often referred
to as “prime movers” are: Gas turbines (or combustion turbines). Such turbines revolutionized airplane
propulsion in the 1940s. Since the 1990s they have become a popular choice
for power generation systems, including CHP. In this technology, air is taken in, compressed,
burned with a fuel (usually natural gas),… …and then ejected to drive a turbine
that generates mechanical power. Heat can be recovered from the exhaust
and put to use for heating,… …cooling, or other industrial processes. Gas turbines exploit the Brayton-Joule cycle,… …in the slide we can see the basic scheme
of an unregenerated (whithout preheating of air)… …open (without exaust gas recirculation) plant. A second technology that is used,
is that of Steam turbines. In this kind of turbines, water is pressurized,
heated by a burning fuel, and converted to steam,… …which is then used to drive a turbine that generates power. The steam turbine was the earliest… …prime moverused in large-scale power generation, dating back to the late 1800s. In a CHP system, any exhaust steam left after the
power-generation step can be put to productive use. Steam cycles are the most used for generating electricity. The advantage of this technology lies in the… …possibility of using low-grade fuels such as carbon and heavy oils since steam plants are external combustion… …systems where combustion products give their heat to another fluid rather than directly evolve in machines. A simplified scheme of a generic
steam plant is proposed. Water is brought to high pressure through
a pump (step 1). In boiler C the water vaporises first (step 2)
and then the steam is overheated (step 3)… …at the expense of the thermal energy released
by a certain amount of fuel (mc). The steam obtained is sent to a turbine where it expands to the condensation pressure (step 4),… …giving energy to the movable organs of the machine. The turbine is therefore able… …to actuate the electric generator (G)
from which electric energy Eel is obtained. To close the cycle, steam must be returned
to the liquid phase through a condenser. The energy extracted from the process fluid
in the condenser is precisely… …the heat lost by the thermodynamic cycle.
What prevents the use of such heat is that,… …in order to increase the cycle efficiency,
the pressure and condensation temperature… …are maintained to the lowest possible level… …(usually at temperatures of 35 ºC to
which it corresponds to about 0.05 bar). Steam turbines can have multiple
stages, up to three,… …depending on the vapor pressure decreasing
as the contained energy is converted to work,… …as shown in Figure 7 in order to best
exploit the enthalpy… …of the fluid that is its energy content. Some modifications to the basic thermodynamic
cycle should be introduced… …in order to make the plant
suitable for cogeneration,… …thus providing heat to temperatures compatible
with those of the users. Consequently, counter-pressure or steam escape systems are produced electrical energy. In the counter-pressure plants,
the steam condenser is bypassed… …and the vapor leaving the turbine
is sent to a heat exchanger… …where it condenses giving heat to another heat transfer medium that feeds a thermal user. …The higher condensing temperature… …in this case results in higher
condensing pressures,… …with mechanical loss and therefore
less electrical energy. In steam escape plants,
cogeneration is done by taking… …a certain amount of steam upstream
or at an (or more)… …intermediate stage of the turbine,
to be sent to a thermal user. This configuration is largely adopted
in industrial contexts where,… …for technological and production needs, electrical
and steam power is required at the same time. By varying the flow rate of the steam,… …it is therefore possible to change the power/heat
ratio of the plant. The third tecnology consist
of Reciprocating engines. Such engines are used in most motor vehicles,… …and the technology has significantly improved
in electrical efficiencies over the past few decades. The engines have a combustion
chamber in which fuel is burned. The combustion pushes a piston that
drives a crankshaft to generate power. Heat can be recovered from the exhaust (high temperature about 450 ºC)… …and from the cooling water of the cylinders
and put to use (low temperature about 130 ºC). Internal Combustion Engines are liable
to cogeneration… …in a fairly wide range of power,
with the smallest units… …from a few tens of kWe being able to reach
some MW of electrical power. In a Otto cycle engine, a mixture of air
and fuel is compressed into a cylinder… …and ignition is carried out by means
of an externally driven device (candle). This is the case of ignition commanded.
In a Diesel engine only the air is compressed… …in the cylinder while the fuel is injected
at the end of the compression phase… …and, due to the high compressed air temperature, combustion starts spontaneously. Diesel cycle engines are used to Cogeneration
when combustibles.. …suitable for compression ignition
are available, such as diesel… …and various types of oils,
including vegetable oils. There are also dual fuel versions in which
a Diesel cycle engine aspires… …an air-methane mixture but also runs a small
fuel injection to start combustion. Other tecnologies: There are other technologies
for CHP as microturbines,… …stirling engines, but are utilized
in small cogeneration systems… …that required low power,
and for this reason we not consider them;… …Fuel Cells (FC), is the only other
technology actually avalaible… …for industrial processes and can
evolve rapidly to give… …a contribute to industrial energy demands. Fuel cells electrochemically convert
fuel to generate electricity. The principle of operation is based
on an electrochemical reaction… …that uses the energy contained in the fuel,
thanks to the ion exchange which takes place… …in suitable membranes to them permeable.
During this process are generated… …electricity and heat that can be recovered
and used for other purposes. In order to explain the operation usually
we are referring to the combination… …of hydrogen and oxygen, but there
may be chemical reactions that use… …different substances that thus result
in different cell characteristics. A fossil fuel, such as natural gas, can be
chemically reformed to produce hydrogen. Howewer it has some limit to their diffusion:
the high cost of production… …and in technology that,
for some types of FC,… …has not yet reached full maturity and presents problems of corrosion resistance… …and/or thermal stress for
high temperature cells. There are in fact many types of FC characterized
by technologies different. The nature of the operating principle is, however,
the same, and it is possible to describe… …its basic aspects by referring to a PEM
(Proton Exchange Membrane). Let’s see a short video that explain
the principle of operation. An interesting feature of fuel cells is that yields do not depend on power sizes, as opposed… …to traditional power generation systems,
indeed the performance is intrinsic… …to the operation of the elementary component.
Another important feature is that partial-load… …operation of FCs does not lead to performance degradation, but rather yields slightly higher yields… …than reduced loads, and even in this,
FCs overcome the performance of thermal machines. In the current slide we can see a comparison
of the main characteristics… …that characterize the technologies
used in cogeneration,… ..bearing in mind that only the first three (large scale)
are those used at the industrial level. 2.4 Cost and Benefits: Based on the indications provided by the EU with the RED and EED directives,… …the use of resources to be sustainable
must be optimized,… …and this is the reason why policy makers
and industry are pursuing CHP tecnology. CHP systems are attractive because they can deliver a variety of energy, environmental and economic benefits. These benefits stem from the fact that these applications produce energy where it is needed,… …avoid wasted heat, and reduce T&D
network and other energy losses. Other benefits cited by policy makers
and industry include: – Cost savings for the energy consumer due
to higher efficiency. – Lower CO2 emissions. – Reduced reliance on imported fossil fuels. – Reduced investment in energy
system infrastructure. – Reduced loss of T&D of electricity due to local production and consumption. – Enhanced electricity network stability through reduction in congestion and ‘peak-shaving’. – Beneficial use of local and surplus energy resources (particularly through the use of waste,… …biomass and geothermal resources
in district heating/cooling systems). – Possibility to operate the cogeneration systems also in “Stand Alone” mode, reducing the risk… …of interruption of power supply for network disruption, a condition of fundamental importance… …in all those contexts where the continuity of the supply of electric energy must be guaranteed. However, it is good to underline
the main limits to be taken… …into account when evaluating
a cogenerative plant. The principle of cogeneration,
although generally valid,… …can not be applied energetically and economically
if the following conditions are not met: 1. Presence and closeness of heat users:
for a cogenerative plant to be convenient… …it is necessary to have a thermal consumer,
as the case of food industry processes, or civil. 2. Contemporary Users: The demand for thermal
and electrical energy must be contemporary. A cogeneration plant is typically able to provide
heat and electricity simultaneously,… …therefore it is necessary for the users
to simultaneously absorb such energy. If the cogeneration plant is insufficient to fully
meet the thermal demand of the user,… …an auxiliary thermal system
can be introduced. 3. Flexibility of the system: Although the demand for heat and electricity by a user… …is simultaneously present, sometimes the ratio between the energy required in the two forms may vary. It may happen that at certain times the demand
for electricity is proportionally greater… …than the thermal one or vice versa. It is generally appreciated that a cogeneration… …system can vary its heat to power ratio;
Not all the engine systems on which… …a cogeneration plant can be based
offer this possibility,… …so if some flexibility is required,
certain technical solutions must be abandoned. It should be noted, however, that in order
to be able to operate with high overall… …yields justifying plants investments, the relationship between the electricity produced… …and the thermal energy used must be maintained as far as possible within the defined limits. 4. Cost of investment: In addition to
the cost benefit analysis associated… …with the cogeneration technology,
consideration must be given to any facilitations… …that may arise from state laws that encourage
the use of renewable sources (as a biomass). They offer tax relief for companies that engage
in the policy of increasing the ‘ Energy efficiency… …and reduction of greenhouse gas emissions,
reducing the return on investment. An application of CHP in Italy: INALCA meat processing plant,
in Ospedaletto Lodigiano (Lodi) Thanks for your attention!