Method for correcting the thermal efficiency of a waste incineration power plant

Abstract

The present invention discloses a method for correcting the thermal efficiency of a waste incineration power plant, which belongs to the technical field of waste incineration. The method comprises the following steps: obtaining the thermal efficiency η of the boiler according to the heat balance method b ; According to the heat balance method, the low calorific value Q of the garbage entering the furnace is obtained net ; Correct the boiler thermal efficiency to obtain the boiler thermal efficiency correction coefficient C1; obtain the pipeline efficiency η based on the heat consumption of the steam turbine and the heat load of the boiler p ; Correct the heat consumption of the steam turbine to obtain the heat consumption correction coefficient C2 of the steam turbine; According to the definition of the heat consumption rate of the steam turbine, the heat consumption rate HR of the steam turbine generator set is obtained; According to the heat consumption rate HR of the steam turbine generator set, the absolute electrical efficiency η of the steam turbine generator set is obtained e According to the above steps, the corrected thermal efficiency η of the waste incineration power plant is obtained. cp The present invention can reduce the deviation between the calculated result and the actual result by introducing the correction coefficient, thereby improving the accuracy of the thermal efficiency of the whole waste incineration power plant.

Description

Technical Field

[0001] The invention belongs to the technical field of waste incineration, and in particular relates to a method for correcting the overall thermal efficiency of a waste incineration power plant. Background Art

[0002] The technology of incineration of domestic waste for power generation has the characteristics of significant reduction of domestic waste, outstanding resource utilization and perfect harmless treatment process. It has been widely promoted and applied in my country in recent years and has become the main treatment method for domestic waste in major cities and towns in my country. However, with the influence of factors such as the improvement of environmental protection requirements of projects and the increase of operating costs of power plants, the profit margin of waste incineration power generation projects has been gradually compressed. Therefore, the development of high-efficiency waste incineration power generation technology and the improvement of the thermal efficiency of the whole waste incineration power generation plant have become important trends in the industry. Therefore, it has become an urgent and extremely important task to theoretically calculate the thermal economy of the newly developed high-efficiency waste incineration power generation technology and accurately evaluate the thermal efficiency level of the new technology by means of performance tests, which provides theoretical and experimental basis for the promotion of new technologies of high-efficiency waste incineration power generation.

[0003] However, large-scale waste incineration power generation technology started late, and the relevant technical standard system is not perfect. The performance test methods and equipment are all based on the experience of thermal power plants. Although some of the main equipment of thermal power plants and waste incineration power plants are similar, there are still differences in the details of the thermal system. These differences have a great impact on the selection of calculation formulas and results for the thermal efficiency of the entire plant.

[0004] During the performance test of the existing waste incineration power plant, the engineering test personnel follow the calculation method of the thermal efficiency of the whole plant in the performance test of the thermal power plant, and still use the formula: η cp =η b ×η p ×η e to perform the calculation.

[0005] After the above theoretical calculations, the results calculated according to the definition of the thermal efficiency of the whole plant are quite different from those calculated by multiplying the efficiencies, with a relative error of >+5%. The efficiency of a medium-temperature medium-pressure waste incineration power plant is generally around 22%. If the calculated result has a deviation of +5%, it means that the efficiency of the waste incineration power plant is as high as 23.1%, and the absolute value of the thermal efficiency of the whole plant is 1.1% higher. The huge difference between the results calculated by the two methods has forced us to carefully consider the applicability of directly and mechanically introducing the calculation experience of the thermal efficiency of the whole plant of a thermal power plant into a waste incineration power plant.

[0006] Therefore, for the calculation of the thermal efficiency of the whole plant, on the basis of drawing on the thermal efficiency calculation of thermal power plants and combining the theory of thermal power plants, finding a more accurate method for calculating the thermal efficiency of the whole plant that reflects the heat utilization level of waste incineration power plants has become an urgent need for the majority of waste incineration power generation technology R&D personnel, engineering test personnel and power plant operators. Summary of the invention

[0007] Technical problem to be solved: In response to the above technical problem, the present invention provides a method for correcting the thermal efficiency of the entire waste incineration power plant, which can reduce the deviation between the calculated results and the actual results and improve the accuracy of the thermal efficiency of the entire plant.

[0008] Technical solution: A method for correcting the thermal efficiency of a waste incineration power plant, the method comprising the following steps:

[0009] Step 1. Obtain boiler thermal efficiency η according to the heat balance method b ;

[0010] Step 2. Obtain the low calorific value Q of the waste entering the furnace according to the heat balance method net ;

[0011] Step 3. Correct the boiler thermal efficiency to obtain the boiler thermal efficiency correction coefficient C1, which is calculated as follows:

[0012] C1=(Q 垃圾 +Q 一次风 )×Q b / [(Q b +Q 抽 +Q pw )×Q 垃圾 ]

[0013] Where Q 垃圾 =B×Q net ;Q 一次风 =D 一次风× (I ” -I ’ );Q b =D0×(h0-h gs ), if there is reheating, then Q b =D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ );Q 抽 =D 抽 ×(h 抽 -h gs );Q pw =D pw ×(h pw -h gs);

[0014] Step 4. Obtain the pipeline efficiency η based on the heat consumption of the steam turbine and the heat load of the boiler p ;

[0015] Step 5. Correct the heat consumption of the steam turbine to obtain the heat consumption correction coefficient C2 of the steam turbine. The calculation method is as follows:

[0016] C2=1+ε

[0017] Where ε represents the steam turbine extraction heat loss coefficient caused by air preheater extraction, and the calculation formula is as follows:

[0018] ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-h gs )]

[0019] If there is reheating,

[0020] ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ )];

[0021] Step 6. According to the definition of steam turbine heat rate, obtain the heat rate HR of the steam turbine generator set;

[0022] Step 7. According to the heat rate HR of the steam turbine generator set, the absolute electrical efficiency η of the steam turbine generator set is obtained. e ;

[0023] Step 8. According to the above steps, the corrected thermal efficiency η of the waste incineration power plant is obtained. cp , which is calculated as follows:

[0024] η cp =η b ×C1×η p ×C2×η e ;

[0025] Among them, the Q 垃圾 represents the heat input from garbage, Q 一次风 Indicates the total input heat of primary air, Q b Indicates boiler heat load, Q 抽 Indicates the heat of saturated steam used to heat the primary air, Q pw Indicates the heat of wastewater discharge, Q netIndicates the low calorific value of the garbage entering the furnace, in kJ / h;

[0026] B represents the amount of waste entering the furnace, in kg / h;

[0027] The D 一次风 represents the primary air volume, D0 represents the boiler superheated steam volume under rated conditions, D zr Indicates the reheat steam flow rate of the reheater, D 抽 Indicates the saturated steam flow rate for heating the primary air, D pw Indicates the sewage flow rate, D 一抽 It indicates the steam volume extracted from one section of the heating primary air, in kg / h;

[0028] I ” represents the air enthalpy at the outlet of the air preheater, I ’ It represents the air enthalpy at the air preheater inlet, and the unit is kJ / kg air;

[0029] h0 represents the specific enthalpy of superheated steam at the boiler outlet, h gs represents the specific enthalpy of boiler feed water, h zr1 ” Indicates the specific enthalpy of the steam entering the low-pressure cylinder of the reheat unit, h zr1 ’ It represents the exhaust enthalpy of high pressure cylinder of reheat unit, h 抽 Indicates the specific enthalpy of saturated steam extracted after heating once, h pw It represents the specific enthalpy of sewage, h 一抽 Indicates the specific enthalpy of extraction steam, h 回水 It indicates the specific enthalpy of return water after heating the primary air, and the unit is kJ / kg.

[0030] Preferably, the boiler thermal efficiency η b The calculation method is as follows:

[0031] η b =(Q b +Q 抽 +Q pw ) / (Q b +Q 抽 +Q pw +Q 损失 )

[0032] The Q 损失 It indicates the total heat loss of the waste heat boiler in kJ / h.

[0033] Preferably, the low calorific value of the garbage entering the furnace is Q net The calculation method is as follows:

[0034] Q b +Q 抽 +Qpw +Q 损失 =Q 垃圾 +Q 一次风 =B×Q net +D 一次风 ×(I ” -I ’ ).

[0035] Preferably, the pipeline efficiency η p The calculation method is as follows:

[0036] η p =D0×(h0-h gs ) / [D b ×(h b -h gs )]

[0037] If there is reheating,

[0038] η p =[D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ )] / [D b ×(h b -h gs )+D zr ×(h zr1 ” -h zr1 ’ )]

[0039] The D b Indicates the main steam flow of the boiler, in kg / h; h b It represents the specific enthalpy of main steam at boiler outlet, in kJ / kg.

[0040] Preferably, the pipeline efficiency η p It is 0.98~0.99.

[0041] Preferably, the calculation method of the heat rate HR of the steam turbine generator set is as follows:

[0042] HR=[D0×(h0-h gs )+D 一抽 ×(h 一抽 -h 回水 )] / P e

[0043] If there is reheating,

[0044] HR=[D0×(h0-h gs )+D一抽 ×(h 一抽 -h 回水 )+D zr ×(h zr1 ” -h zr1 ’ )] / P e

[0045] The P e It indicates the generator power at the generator output end under the condition of rated evaporation capacity of the boiler, in kW.

[0046] Preferably, the absolute electrical efficiency η of the steam turbine generator set is e The calculation method is as follows:

[0047] η e =3600 / HR.

[0048] Beneficial effect: The present invention introduces two correction coefficients C1 and C2 in the calculation of the thermal efficiency of the whole plant in the performance test of the waste incineration power plant, which are respectively used to correct the boiler efficiency calculated by the heat balance method and the steam turbine heat consumption loss caused by the steam turbine extraction due to the extra consumption of heating the primary air. This makes the calculation of the thermal efficiency of the whole plant in the current waste incineration power generation performance test more accurate, and reduces the deviation between the results calculated by conventional methods and the actual results. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flow chart used to correct the thermal efficiency of the entire waste incineration power plant. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] like Figure 1 As shown, the thermal efficiency of the whole plant for waste incineration power plant is calculated and corrected according to the following process:

[0053] ①Boiler thermal efficiency η b Calculation:

[0054] According to the FDBR standard, the heat balance method is used to measure and calculate the boiler flue gas heat loss, radiation and conduction heat loss, slag incomplete combustion heat loss, fly ash incomplete combustion heat loss and flue gas CO incomplete combustion heat loss. Based on the data obtained, the thermal efficiency of the incinerator-waste heat boiler during the test is calculated.

[0055] According to the heat balance:

[0056] Total heat input = total heat output = effective heat utilization by boiler + total heat loss

[0057] The boiler thermal efficiency η b The calculation formula is:

[0058] η b = boiler effective heat utilization / total heat input = boiler effective heat utilization / (boiler effective heat utilization + total heat loss) = (Q b +Q 抽 +Q pw ) / (Q b +Q 抽 +Q pw +Q 损失 ).

[0059] ② Low calorific value of garbage entering the furnace Q net According to the heat balance method, we can calculate:

[0060] Q b +Q 抽 +Q pw +Q 损失 =Q 垃圾 +Q 一次风 =B×Q net +D 一次风 ×(I ” -I ’ ).

[0061] ③Calculation of boiler thermal efficiency correction coefficient C1:

[0062] C1=(Q 垃圾 +Q 一次风 )×Q b / [(Q b +Q 抽 +Q pw )×Q 垃圾 ]

[0063] Where Q 垃圾 =B×Q net ;Q 一次风 =D 一次风× (I ” -I ’ );Q b =D0×(h0-h gs ), if there is reheating, Q b =D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ );Q 抽 =D 抽 ×(h 抽 -h gs);Q pw =D pw ×(h pw -h gs ).

[0064] ④ Pipeline efficiency η p Calculation:

[0065] η p =Q0 / Q b＝ D0×(h0-h gs ) / [D b ×(h b -h gs )]

[0066] If there is reheating,

[0067] η p =Q0 / Q b＝ [D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ )] / [D b ×(h b -h gs )+D zr ×(h zr1 ” -h zr1 ’ )]

[0068] Generally, the value taken according to experience is 0.98-0.99.

[0069] ⑤ Calculation of steam turbine heat consumption correction factor C2;

[0070] C2=1+ε

[0071] Among them, ε is the steam turbine extraction heat loss coefficient caused by air preheater extraction. The size of ε represents the ratio of the steam loss from the steam turbine to the air preheater to the main steam and reheat steam in the heat consumption of the steam turbine. The calculation formula is as follows:

[0072] ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-h gs )]

[0073] If there is reheating,

[0074] ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-hgs )+D zr ×(h zr1 ” -h zr1 ’ )].

[0075] ⑥ Calculation of HR of the heat rate of the steam turbine generator set;

[0076] According to the definition of steam turbine heat rate, HR = (total heat input to the steam turbine system - total heat output to the steam turbine system) / P e

[0077] =(D0×h 0+ D 一抽 ×h 一抽 -D0×h gs -D 一抽 ×h 回水 / P e

[0078] =[D0×(h0-h gs )+D 一抽 ×(h 一抽 -h 回水 )] / P e

[0079] If there is reheating,

[0080] HR=[D0×(h0-h gs )+D 一抽 ×(h 一抽 -h 回水 )+D zr ×(h zr1 ” -h zr1 ’ )] / P e .

[0081] ⑦ Absolute electrical efficiency η of steam turbine generator set e Calculation of

[0082] According to the relationship between absolute electrical efficiency and heat consumption,

[0083] η e =3600 / HR

[0084] ⑧ Thermal efficiency of the whole plant η cp Calculation:

[0085] The thermal efficiency of the whole plant is calculated according to the definition formula and the following formula:

[0086] η cp =3600P e / (B×Qnet ) = η b ×C1×η p ×C2×η e

[0087] where η b , η p , η e They are obtained by conventional methods in current performance tests (see steps ①, ④, and ⑦ for specific calculation formulas). C1 and C2 are two correction coefficients newly introduced in the present invention, and the specific calculation methods are shown in steps ③ and ⑤.

[0088] In the above formulas, Q 垃圾 represents the heat input from garbage, Q 一次风 Indicates the total input heat of primary air, Q b Indicates boiler heat load, Q 抽 Indicates the heat of saturated steam used to heat the primary air, Q pw Indicates the heat of wastewater discharge, Q net Indicates the low calorific value of the garbage entering the furnace, Q 损失 It represents the total heat loss of waste heat boiler, Q0 represents the heat consumption of steam turbine, both in kJ / h;

[0089] B represents the amount of waste entering the furnace, in kg / h;

[0090] The D 一次风 represents the primary air volume, D0 represents the boiler superheated steam volume under rated conditions, D zr Indicates the reheat steam flow rate of the reheater, D 抽 Indicates the saturated steam flow rate for heating the primary air, D pw Indicates the sewage flow rate, D 一抽 Indicates the amount of steam extracted from one section of heating primary air, D b Indicates the main steam flow rate of the boiler, in kg / h;

[0091] I ” represents the air enthalpy at the outlet of the air preheater, I ’ It represents the air enthalpy at the air preheater inlet, and the unit is kJ / kg air;

[0092] h0 represents the specific enthalpy of superheated steam at the boiler outlet, h gs represents the specific enthalpy of boiler feed water, h zr1 ” Indicates the specific enthalpy of the steam entering the low-pressure cylinder of the reheat unit, h zr1 ’ It represents the exhaust enthalpy of high pressure cylinder of reheat unit, h 抽 Indicates the specific enthalpy of saturated steam extracted after heating once, h pw It represents the specific enthalpy of sewage, h 一抽 Indicates the specific enthalpy of extraction steam, h回水 Indicates the specific enthalpy of return water after heating the primary air, h b It indicates the specific enthalpy of main steam at boiler outlet, in kJ / kg;

[0093] The P e It indicates the generator power at the generator output end under the condition of rated evaporation capacity of the boiler, in kW.

[0094] The present invention introduces two correction coefficients C1 and C2 in the calculation of the thermal efficiency of the whole plant in the performance test of the waste incineration power plant, which are respectively used to correct the boiler efficiency calculated by the heat balance method and the steam turbine heat consumption loss caused by the steam turbine extraction due to the extra consumption of heating primary air. This makes the calculation of the thermal efficiency of the whole plant in the current waste incineration power generation performance test more accurate and reduces the deviation between the results calculated by conventional methods and the actual results.

Claims

1. A method for correcting the thermal efficiency of a waste incineration power plant, characterized in that: The method comprises the following steps: Step 1. Obtain boiler thermal efficiency η according to the heat balance method b ; Step 2. Obtain the low calorific value Q of the waste entering the furnace according to the heat balance method net ; Step 3. Correct the boiler thermal efficiency to obtain the boiler thermal efficiency correction coefficient C1, which is calculated as follows: C1=(Q 垃圾 +Q 一次风 )×Q b / [(Q b +Q 抽 +Q pw )×Q 垃圾 ] Where Q 垃圾 =B×Q net ;Q 一次风 =D 一次风× (I ” -I ’ );Q b =D0×(h0-h gs ), if there is reheating, then Q b =D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ );Q 抽 =D 抽 ×(h 抽 -h gs );Q pw =D pw ×(h pw -h gs ); Step 4. Obtain the pipeline efficiency η based on the heat consumption of the steam turbine and the heat load of the boiler p ; Step 5. Correct the heat consumption of the steam turbine to obtain the heat consumption correction coefficient C2 of the steam turbine. The calculation method is as follows: C2=1+ε Where ε represents the steam turbine extraction heat loss coefficient caused by air preheater extraction, and the calculation formula is as follows: ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-h gs )] If there is reheating, ε=D 一抽 ×(h 一抽 -h 回水 ) / [D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ )]; Step 6. According to the definition of steam turbine heat rate, obtain the heat rate HR of the steam turbine generator set; Step 7. According to the heat rate HR of the steam turbine generator set, the absolute electrical efficiency η of the steam turbine generator set is obtained. e ; Step 8. According to the above steps, the corrected thermal efficiency η of the waste incineration power plant is obtained. cp , which is calculated as follows: or cp =the b ×C1×η p ×C2×η e ; Among them, the Q 垃圾 represents the heat input from garbage, Q 一次风 Indicates the total input heat of primary air, Q b Indicates boiler heat load, Q 抽 Indicates the heat of saturated steam used to heat the primary air, Q pw Indicates the heat of sewage discharge, Q net Indicates the low calorific value of the garbage entering the furnace, in kJ / h; B represents the amount of waste entering the furnace, in kg / h; The D 一次风 represents the primary air volume, D0 represents the boiler superheated steam volume under rated conditions, and D zr Indicates the reheat steam flow rate of the reheater, D 抽 Indicates the saturated steam flow rate for heating the primary air, D pw Indicates the sewage flow rate, D 一抽 It indicates the steam volume extracted from one section of the heating primary air, in kg / h; I ” represents the air enthalpy at the outlet of the air preheater, I ’ represents the air enthalpy at the air preheater inlet, in kJ / kg air; h0 represents the specific enthalpy of superheated steam at the boiler outlet, h gs represents the specific enthalpy of boiler feed water, h zr1 ” Indicates the specific enthalpy of the steam entering the low-pressure cylinder of the reheat unit, h zr1 ’ It represents the exhaust enthalpy of high pressure cylinder of reheat unit, h 抽 Indicates the specific enthalpy of saturated steam extracted after heating once, h pw It represents the specific enthalpy of sewage, h 一抽 Indicates the specific enthalpy of extraction steam, h 回水 It indicates the specific enthalpy of return water after heating the primary air, and the unit is kJ / kg.

2. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The boiler thermal efficiency η b The calculation method is as follows: the b =(Q b +Q 抽 +Q pw ) / (Q b +Q 抽 +Q pw +Q 损失 ) The Q 损失 It indicates the total heat loss of the waste heat boiler in kJ / h.

3. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The low calorific value of the garbage entering the furnace is Q net The calculation method is as follows: Q b +Q 抽 +Q pw +Q 损失 =Q 垃圾 +Q 一次风 =B×Q net +D 一次风 ×(I ” -I ’ )。 4. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The pipeline efficiency η p The calculation method is as follows: η p =D0×(h0-h gs ) / [D b ×(h b -h gs )] If there is reheating, η p =[D0×(h0-h gs )+D zr ×(h zr1 ” -h zr1 ’ )] / [D b ×(h b -h gs )+D zr ×(h zr1 ” -h zr1 ’ )] The D b Indicates the main steam flow rate of the boiler, in kg / h; h b It represents the specific enthalpy of main steam at boiler outlet, in kJ / kg.

5. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The pipeline efficiency η p It is 0.98~0.

99.

6. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The calculation method of the heat rate HR of the steam turbine generator set is as follows: HR=[D0×(h0-h gs )+D 一抽 ×(h 一抽 -h 回水 )] / P e If there is reheating, HR=[D0×(h0-h gs )+D 一抽 ×(h 一抽 -h 回水 )+D zr ×(h zr1 ” -h zr1 ’ )] / P e The P e It indicates the generator power at the generator output end under the condition of rated evaporation capacity of the boiler, in kW.

7. The method for correcting the thermal efficiency of a waste incineration power plant according to claim 1, characterized in that: The absolute electrical efficiency η of the steam turbine generator set e The calculation method is as follows: η e =3600 / HR。

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