internal class Program
{
    static void Main(string[] args)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Name", typeof(string));
        dt.Columns.Add("Age",typeof(int));
        dt.Rows.Add("test1", 22);
        dt.Rows.Add("test2", 21);
        dt.Rows.Add("test3", 25);
        DataSet set = new DataSet();
        set.Tables.Add(dt);
        ExportDataSet(set, "test.xlsx");

        

    }
    private static void ExportDataSet(DataSet ds, string destination)
    {
        using (var workbook = SpreadsheetDocument.Create(destination, DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook))
        {
            var workbookPart = workbook.AddWorkbookPart();

            workbook.WorkbookPart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();

            workbook.WorkbookPart.Workbook.Sheets = new DocumentFormat.OpenXml.Spreadsheet.Sheets();

            foreach (System.Data.DataTable table in ds.Tables)
            {

                var sheetPart = workbook.WorkbookPart.AddNewPart<WorksheetPart>();
                var sheetData = new DocumentFormat.OpenXml.Spreadsheet.SheetData();
                sheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet(sheetData);

                DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = workbook.WorkbookPart.Workbook.GetFirstChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>();
                string relationshipId = workbook.WorkbookPart.GetIdOfPart(sheetPart);

                uint sheetId = 1;
                if (sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Count() > 0)
                {
                    sheetId =
                        sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Select(s => s.SheetId.Value).Max() + 1;
                }

                DocumentFormat.OpenXml.Spreadsheet.Sheet sheet = new DocumentFormat.OpenXml.Spreadsheet.Sheet() { Id = relationshipId, SheetId = sheetId, Name = table.TableName };
                sheets.Append(sheet);

                DocumentFormat.OpenXml.Spreadsheet.Row headerRow = new DocumentFormat.OpenXml.Spreadsheet.Row();

                List<String> columns = new List<string>();
                foreach (System.Data.DataColumn column in table.Columns)
                {
                    columns.Add(column.ColumnName);

                    DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
                    cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
                    cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(column.ColumnName);
                    headerRow.AppendChild(cell);
                }


                sheetData.AppendChild(headerRow);

                foreach (System.Data.DataRow dsrow in table.Rows)
                {
                    DocumentFormat.OpenXml.Spreadsheet.Row newRow = new DocumentFormat.OpenXml.Spreadsheet.Row();
                    foreach (String col in columns)
                    {
                        DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
                        cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
                        cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(dsrow[col].ToString()); //
                        newRow.AppendChild(cell);
                    }

                    sheetData.AppendChild(newRow);
                }

            }
        }
    }

}