Calculation of heat rate & efficiency of the power plant

1. Heat rate =Heat input / Power generation.
2. Example: A 100 MW thermal power plant is running on 100% PLF, which consumes around 55 MT of coal having GCV 4500 kcal/kg per hour, then calculate the Gross station heat rate of the plant.

The heat rate is the amount of energy used by an electrical generator/power plant to generate one kilowatthour (kWh) of electricity. The U.S. Energy Information Administration (EIA) expresses heat rates in British thermal units (Btu) per net kWh generated.

The heat rate is defined as the total amount of energy required to produce one kilowatt-hour (kWh) of electricity by an electric generator or power plant. It is the input rate required for generating unit power. The heat rate can also be described as the ratio of thermal inputs to electrical output.

Net Heat Rate = Gross Heat Rate / (1- APC%) Parameter.

The heat rate curve plots the heat energy required per MWH of generated electrical output for the generator as a function of the generator’s MW output. Thus, the heat rate curve indicates the efficiency of the unit over its operating range.

For example, if the boiler runs for 1,800 seconds, dividing 12,558,000 by 1,800 gives 6,977, or a little under 7,000. This is the heat input rate, measured in joules per second, or Watts. Divide the heat input rate by 1,000 to convert it to kilowatts. 7,000 divided by 1,000 gives a rate of 7 kW.

The heat input rate is the maximum rate of energy flow into an appliance, calculated as the rate of fuel flow to the appliance multiplied by either the fuel’s gross or net calorific value.

Heat rate improvement can be achieved by reducing warm-up water flow rates from operating pumps to idle pumps. Less warm-up water flow will reduce the auxiliary power of the operating pumps. Minimizing flow, pressure, and temperature oscillations during cycling operation.

Energy Management Residential furnaces have a heat input rate of less than 225,000 Btu h−1 (66 kW) and residential boilers have a heat input rate of less than 300,000 Btu h−1 (88 kW). A condensing furnace condenses the water vapor produced in the combustion process and uses the heat from this condensation.

Technically speaking, heat input is the amount of electrical energy supplied by a welding arc to a workpiece. Heat input is important because it affects weld cooling rates, which in turn affects the heat affected zone and the microstructure of welded materials.

Input is the amount of BTU’s of the fuel you put in… Output is the actual amount of heat that the heater puts out for the Input. The difference between the input and the actual heating output allows you to figure the efficiency of your boiler / heater.

The input is what the boiler actually consumes, as measured by your gas meter and charged on your bill. The output is the amount of heat which is used to heat the water. The difference between the two figures is the heat lost inside the boiler – warming the casing, escaping up the flue etc.

The measured heat transfer efficiency for GMAW-P varied slightly over a wide range of pulse parameters, with an average value of 70%, a maximum of 72% and a minimum of 68%. Mathematical analysis shows that average instantaneous power values must be used when current and voltage vary significantly with time.

Q=C(TB−TA). This equation always puzzled me. The main issue is that this is the heat transfer in a process where system B is taken from initial state ξ1 with temperature TB to the final state ξ2 with temperature TA.

There is a heat input restriction applied to those steels that will experience joint strength reduction upon welding; typically a maximum heat input of 2.5kJ/mm for 15mm thickness. This value is dependent on the steel grade, and is more critical for higher strength steels that have had more rapid cooling.

Travel speed is simply the speed at which the welding torch or gun is moved across the workpiece – measured in millimeters per minute. Alongside voltage and amperage, travel speed is one of the three variables in arc welding that determines the amount of heat input.

The process of preheating involves heating the area around the weld joint or the entire part to a specified temperature before welding. This reduces the cooling rate of the weld and drives out moisture, which in turn helps prevent hydrogen buildup and the potential for cracking.

Conversely, welding heat input that is too low can also cause problems. Welding on heavy sections of steel with low heat input or small welding beads can cause the welds to cool too quickly, producing above-normal hardness values in the heat-affected zone (HAZ) or in the weld bead.

Although the hardness decreases, the heat-treated hardness is still greater than the as-cast state. After destabilisation treatment at 1130°C, tempering at 200 to 250°C for 3 hours leads to the highest impact toughness, and secondary hardening was observed when tempering over 400°C.

HAZ problems can be mitigated by performing a pre- and/or post-weld heat treatment. Weld geometry also plays a role in the size of the HAZ. During high-temperature cutting operations, the depth of the HAZ is associated with the cutting process, cutting speed, material properties, and material thickness.

To answer your original question, welding heat input calculation is defined by voltage, amperage, and travel speed, and it is generally expressed as kilojoules per linear inch of weld (kJ/in.). The general heat input range recommended for welding various types of carbon steel and specialty alloys is 30 to 70 kJ/in.

How To Calculate Heat Input From Welding

1. Heat Input = (60 x Amps x Volts) / (1,000 x Travel Speed in in/min) = KJ/in.
2. Travel Speed = Length of Weld / Time to weld = 25 inches / 2 minutes = 12.5 inches per minute.
3. Heat Input = [(60 sec/min) x (325 amps) x (29 volts)] / [(1,000 joules/kilojoule) x (12.5 inches/minute)]

heat imput

The heat affected zone (HAZ) is a non-melted area of metal that has undergone changes in material properties as a result of being exposed to high temperatures. These changes in material property are usually as a result of welding or high-heat cutting.

WELDING PROCEDURES

• 5 essentials for proper welding procedures.
• 1) CORRECT ELECTRODE SIZE.
• 2) CORRECT CURRENT.
• 3) CORRECT ARC LENGTH or VOLTAGE.
• 4) CORRECT TRAVEL SPEED.
• 5) CORRECT ELECTRODE ANGLE.
• 8 FACTORS to consider in selecting arc welding electrodes.

laser beam welding

Dilution is defined as the change in composition of the weld metal caused by the mixing of the base metal or the previously deposited weld metal. In this investigation the effect of welding parameters on dilution was studied by taking conventional TIG and MIG welding processes.

Traditionally, the term weld overlay is used to define applications of welding processes to deposit one or more layers of metal with specific characteristics on a base metal to improve desirable properties that are not inherent to the base metal or to restore the original dimension of the component.

a rough way of calculating weld metal dilution is to divide weight of weld metal against weight of base metal to give you a percentage figure. A weld with no filler wire (autogenous) would therefore be 100% dilution as it has no other additions.

CRA refers to corrosion-resistant alloy. The CRA cladded steel pipe is composed of a conventional carbon steel or low alloy steel pipe and a corrosion-resistant alloy layer. The carbon steel or low alloy steel pipe is called base metal, or backing steel. The CRA layer is usually called cladding material or lining.